夹具设计英文文献翻译
夹具设计英文文献
A review and analysis of current computer-aided fixture design approachesIain Boyle, Yiming Rong, David C. BrownKeywords:Computer-aided fixture designFixture designFixture planningFixture verificationSetup planningUnit designABSTRACTA key characteristic of the modern market place is the consumer demand for variety. To respond effectively to this demand, manufacturers need to ensure that their manufacturing practices are sufficiently flexible to allow them to achieve rapid product development. Fixturing, which involves using fixtures to secure work pieces during machining so that they can be transformed into parts that meet required design specifications, is a significant contributing factor towards achieving manufacturing flexibility. To enable flexible fixturing, considerable levels of research effort have been devoted to supporting the process of fixture design through the development of computer-aided fixture design (CAFD) tools and approaches. This paper contains a review of these research efforts. Over seventy-five CAFD tools and approaches are reviewed in terms of the fixture design phases they support and the underlying technology upon which they are based. The primary conclusion of the review is that while significant advances have been made in supporting fixture design, there are primarily two research issues that require further effort. The first of these is that current CAFD research is segmented in nature and there remains a need to provide more cohesive fixture design support. Secondly, a greater focus is required on supporting the detailed design of a fixture’s physical structure.2010 Elsevier Ltd. All rights reserved. Contents1. Introduction (2)2. Fixture design (2)3. Current CAFD approaches (4)3.1 Setup planning (4)3.1.1 Approaches to setup planning (4)3.2 Fixture planning (4)3.2.1 Approaches to defining the fixturing requirement (6)3.2.2 Approaches to non-optimized layout planning (6)3.2.3 Approaches to layout planning optimization (6)3.3 Unit design (7)3.3.1 Approaches to conceptual unit design (7)3.3.2 Approaches to detailed unit design (7)3.4 Verification (8)3.4.1 Approaches to constraining requirements verification (8)3.4.2 Approaches to tolerance requirements verification (8)3.4.3 Approaches to collision detection requirements verification (8)3.4.4 Approaches to usability and affordability requirements verification (9)3.5 Representation of fixturing information (9)4. An analysis of CAFD research (9)4.1 The segmented nature of CAFD research (9)4.2 Effectively supporting unit design (10)4.3 Comprehensively formulating th e fixturing requirement (10)4.4 Validating CAFD research outputs (10)5. Conclusion (10)References (10)1. IntroductionA key concern for manufacturing companies is developing the ability to design and produce a variety of high quality products within short timeframes. Quick release of a new product into the market place, ahead of any competitors, is a crucial factor in being able to secure a higher percentage of the market place and increased profit margin. As a result of the consumer desire for variety, batch production of products is now more the norm than mass production, which has resulted in the need for manufacturers to develop flexible manufacturing practices to achieve a rapid turnaround in product development.A number of factors contribute to an organization’s ability to achieve flexible manufacturing, one of which is the use of fixtures during production in which work pieces go through a number of machining operations to produce individual parts which are subsequently assembled into products. Fixtures are used to rapidly, accurately, and securely position work pieces during machining such that all machined parts fall within the design specifications for that part. This accuracy facilitates the interchangeability of parts that is prevalent in much of modern manufacturing where many different products feature common parts.The costs associated with fixturing can account for 10–20% of the total cost of a manufacturing system [1]. These costs relate not only to fixture manufacture, assembly, and operation, but also to their design. Hence there are significant benefits to be reaped by reducing the design costs associated with fixturing and two approaches have been adopted in pursuit of this aim. One has concentrated on developing flexible fixturing systems, such as the use of phase-changing materials to hold work pieces in place [2] and the development of commercial modular fixture systems. However, the significant limitation of the flexible fixturing mantra is that it does not address the difficulty of designing fixtures. To combat this problem, a second research approach has been to develop computer-aided fixture design (CAFD) systems that support and simplify the fixture design process and it is this research that is reviewed within this paper.Section 2 describes the principal phases of and the wide variety of requirements driving the fixture design process. Subsequently in Section 3 an overview of research efforts that havefocused upon the development of techniques and tools for supporting these individual phases of the design process is provided. Section 4 critiques these efforts to identify current gaps in CAFD research, and finally the paper concludes by offering some potential directions for future CAFD research. Before proceeding, it is worth noting that there have been previous reviews of fixturing research, most recently Bi and Zhang [1] and Pehlivan and Summers [3]. Bi and Zhang, while providing some details on CAFD research, tend to focus upon the development of flexible fixturing systems, and Pehlivan and Summers focus upon information integration within fixture design. The value of this paper is that it provides an in-depth review and critique of current CAFD techniques and tools and how they provide support across the entire fixture design process.2. Fixture designThis section outlines the main features of fixtures and more pertinently of the fixture design process against which research efforts will be reviewed and critiqued in Sections 3 and 4, respectively. Physically a fixture consists of devices that support and clamp a work piece [4,5]. Fig.1 represents a typical example of a fixture in which the work piece rests on locators that accurately locate it. Clamps hold the work piece against the locators during machining thus securing the work piece’s location. The locating units themselves consist of the locator supporting unit and the locator that contacts the work piece. The clamping units consist of a clamp supporting unit and a clamp that contacts the work piece and exerts a clamping force to restrain it.Typically the design process by which such fixtures are created has four phases: setup planning, fixture planning, unit design, and verification, as illustrated in Fig. 2 , which is adapted from Kang et al. [6]. During setup planning work piece and machining information is analyzed to determine the number of setups required to perform all necessary machining operations and the appropriate locating datums for each setup. A setup represents the combination of processes that can be performed on a work piece without having to alter the position or orientation of the work piece manually. To generate a fixture for each setup the fixture planning, unit design, and verification phases are executed.During fixture planning, the fixturing requirements for a setup are generated and the layout plan, which represents the first step towards a solution to these requirements is generated. This layout plan details the work piece surfaces with which the fixture’s locating and clamping units will establish contact, together with the surface positions of the locating and clamping points. The number and position of locating points must be such that a work piece’s six degrees of freedom (Fig. 3 ) are adequately constrained during machining [7] and there are a variety of conceptual locating point layouts that can facilitate this, such as the 3-2-1 locating principle [4]. In the third phase, suitable unit designs (i.e., the locating and clamping units) are generated and the fixture is subsequently tested during the verification phase to ensure that it satisfies the fixturing requirements driving the design process. It is worth noting that verification of setups and fixture plans can take place as they are generated and prior to unit design.Fixturing requirements, which although not shown in Kang et al.[6] are typically generated during the fixture planning phase, can be grouped into six classes ( Table 1 ). The ‘‘physical’’requirements class is the most basic and relates to ensuring the fixture can physically support the work piece. The ‘‘tolerance’’requirements relate to ensuring that the locating tolerances aresufficient to locate the work piece accurately and similarly the‘‘constraining’’ requirements focus on maintaining this accuracy as the work piece and fixture are subjected to machining forces. The ‘‘affordability’’ requirements relate to ensuring the fixture represents value, for example in terms of material, operating, and assembly/disassembly costs.The ‘‘collision detection’’ requirements focus upon ensuring that the fixture does not collide with the machining path, the work piece, or indeed itself. The ‘‘usability’’ requirements relate to fixture ergonomics and include for example needs related to ensuring that a fixture features error-proofing to prevent incorrect insertion of a work piece, and chip shedding, where the fixture assists in the removal of machined chips from the work piece.As with many design situations, the conflicting nature of these requirements is problematic. For example a heavy fixture can be advantageous in terms of stability but can adversely affect cost (due to increased material costs) and usability (because the increased weight may hinder manual handling). Such conflicts add to the complexity of fixture design and contribute to the need for the CAFD research reviewed in Section 3.Table 1Fixturing requirements.Generic requirement Abstract sub-requirement examplesPhysical ●The fixture must be physically capable of accommodatingthe work piece geometry and weight.●The fixture must allow access to the work piece features tobe machined.Toleranc e ●The fixture locating tolerances should be sufficient to satisfypart design tolerances.Constraining●The fixture shall ensure work piece stability (i.e., ensure thatwork piece force and moment equilibrium are maintained).●The fixture shall ensure that the fixture/work piece stiffness issufficient to prevent deformation from occurring that could resultin design tolerances not being achieved.Affordabilit y ●The fixture cost shall not exceed desired levels.●The fixture assembly/disassembly times shall not exceeddesired levels.●The fixture operation time shall not exceed desired levels. CollisionPrevention●The fixture shall not cause tool path–fixture collisions to occur.●The fixture shall cause work piece–fixture collisions to occur(other than at the designated locating and clamping positions).●The fixture shall not cause fixture–fixture collisions to occur(other than at the designated fixture component connectionpoints).Usabilit y ●The fixture weight shall not exceed desired levels.●The fixture shall not cause surface damage at the workpiece/fixture interface.●The fixture shall provide tool guidance to designated workpiece features.●The fixture shall ensure error-proofing (i.e., the fixture shouldprevent incorrect insertion of the work piece into the fixture).●The fixture shall facilitate chip shedding (i.e., the fixture shouldprovide a means for allowing machined chips to flow awayfrom the work piece and fixture).3. Current CAFD approachesThis section describes current CAFD research efforts, focusing on the manner in which they support the four phases of fixture design. Table 2 provides a summary of research efforts based upon the design phases they support, the fixture requirements they seek to address (boldtext highlights that the requirement is addressed to a significant degree of depth, whilst normal text that the degree of depth is lesser in nature), and the underlying technology upon which they are primarily based. Sections 3.1–3.4 describes different approaches for supporting setup planning, fixture planning, unit design, and verification, respectively. In addition, Section 3.5 discusses CAFD research efforts with regard to representing fixturing information.3.1. Setup planningSetup planning involves the identification of machining setups, where an individual setup defines the features that can be machined on a work piece without having to alter the position or orientation of the work piece manually. Thereafter, the remaining phases of the design process focus on developing individual fixtures for each setup that secure the work piece. From a fixturing viewpoint, the key outputs from the setup planning stage are the identification of each required setup and the locating datums (i.e., the primary surfaces that will be used to locate the work piece in the fixture).The key task within setup planning is the grouping or clustering of features that can be machined within a single setup. Machining features can be defined as the volume swept by a cutting tool, and typical examples include holes, slots, surfaces, and pockets [8]. Clustering of these features into individual setups is dependent upon a number of factors (including the tolerance dependencies between features, the capability of the machine tools that will be used to create the features, the direction of the cutting tool approach, and the feature machining precedence order), and a number of techniques have been developed to support setup planning. Graph theory and heuristic reasoning are the most common techniques used to support setup planning, although matrix based techniques and neural networks have also been employed.3.1.1. Approaches to setup planningThe use of graph theory to determine and represent setups has been a particularly popular approach [9–11]. Graphs consist of two sets of elements: vertices, which represent work piece features, and edges, which represent the relationships that exist between features and drive setup identification. Their nature can vary, for example in Sarma and Wright [9] consideration of feature machining precedence relationships is prominent, whereas Huang and Zhang [10] focus upon thetolerance relationships that exist between features. Given that these edges can be weighted in accordance with the tolerance magnitudes, this graph approach can also facilitate the identification of setups that can minimize tolerance stack up errors between setups through the grouping of tight tolerances. However, this can prove problematic given the difficulty of comparing the magnitude of different tolerance types to each other thus Huang [12] includes the use of tolerance factors [13] as a means of facilitating such comparisons, which are refined and extended by Huang and Liu [14] to cater for a greater variety of tolerance types and the case of multiple tolerance requirements being associated with the same set of features.While some methods use undirected graphs to assist setup identification [11] , Yao et al. [15] , Zhang and Lin [16] , and Zhang et al. [17] use directed graphs that facilitate the determination and explicit representation of which features should be used as locating datums ( Fig. 4 ) in addition to setup identification and sequencing. Also, Yao et al. refine the identified setups through consideration of available machine tool capability in a two stage setup planning process.Experiential knowledge, in the form of heuristic reasoning, has also been used to assist setup planning. Its popularity stems from the fact that fixture design effectiveness has been considered to be dependent upon the experience of the fixture designer [18] .To support setup planning, such knowledge has typically been held in the form of empirically derived heuristic rules, although object oriented approaches have on occasion been adopted [19] . For example Gologlu [20] uses heuristic rules together with geometric reasoning to support feature clustering, feature machining precedence, and locating datum selection. Within such heuristic approaches, the focus tends to fall upon rules concerning the physical nature of features and machining processes used to create them [21, 22]. Although some techniques do include feature tolerance considerations [23], their depth of analysis can be less than that found within the graph based techniques [24]. Similarly, kinematic approaches [25] have been used to facilitate a deeper analysis of the impact of tool approach directions upon feature clustering than is typically achieved using rule-based approaches. However, it is worth noting that graph based approaches are often augmented with experiential rule-bases to increase their overall effectiveness [16] .Matrix based approaches have also been used to support setup planning, in which a matrix defining feature clusters is generated and subsequently refined. Ong et al. [26] determine a feature precedence matrix outlining the order in which features can be machined, which is then optimized against a number of cost indicators (such as machine tool cost, change over time, etc.) in a hybrid genetic algorithm-simulated annealing approach through consideration of dynamically changing machine tool capabilities. Hebbal and Mehta [27] generate an initial feature grouping matrix based upon the machine tool approach direction for each feature which is subsequently refined through the application of algorithms that consider locating faces and feature tolerances.Alternatively, the use of neural networks to support setup planning has also been investigated. Neural networks are interconnected networks of simple elements, where the interconnections are ‘‘learned’’ from a set of example data. Once educated, these networks can generate solutions for new problems fed into the network. Ming and Mak [28] use a neural network approach in which feature precedence, tool approach direction, and tolerance relationships are fed into a Kohonen self-organizing neural network to group operations for individual features into setups.3.2. Fixture planningFixture planning involves the comprehensive definition of a fixturing requirement in terms ofthe physical, tolerance, constraining, affordability, collision prevention, and usability requirements listed in Table 1 , and the creation of a fixture layout plan. The layout plan represents the first part of the fixture solution to these requirements, and specifies the position of the locating and clamping points on the work piece. Many layout planning approaches feature verification, particularly with regard to the constraining requirements. Typically this verification forms part of a feedback loop that seeks to optimize the layout plan with respect to these requirements. Techniques used to support fixture planning are now discussed with respect to fixture requirement definition, layout planning, and layout optimization.Fig. 4. A work piece (a) and its directed graphs showing the locating datums (b) (adapted from Zhang et al. [17] ).3.2.1. Approaches to defining the fixturing requirementComprehensive fixture requirement definition has received limited attention, primarily focusing upon the definition of individual requirements within the physical, tolerance, and constraining requirements. For example, Zhang et al. [17] under-take tolerance requirement definition through an analysis of work piece feature tolerances to determine the allowed tolerance at each locating point and the decomposition of that tolerance into its sources. The allowed locating point accuracy is composed of a number of factors, such as the locating unit tolerance, the machine tool tolerance, the work piece deformation at the locating point, and so on. These decomposed tolerance requirements can subsequently drive fixture design: e.g., the tolerance of the locating unit developed in the unit design phase cannot exceed the specified locating unit tolerance. In a similar individualistic vein, definition of the clamping force requirements that clamping units must achieve has also received attention [29,30].In a more holistic approach, Boyle et al. [31] facilitate a comprehensive requirement specification through the use of skeleton requirement sets that provide an initial decomposition of the requirements listed in Table 1, and which are subsequently refined through a series of analyses and interaction with the fixture designer. Hunter et al. [32,33] also focus on functional requirement driven fixture design, but restrict their focus primarily to the physical and constraining requirements.3.2.2. Approaches to non-optimized layout planningLayout planning is concerned with the identification of the locating principle, which defines the number and general arrangement of locating and clamping points, the work piece surfaces they contact, and the surface coordinate positions where contact occurs. For non-optimized layoutplanning, approaches based upon the re-use of experiential knowledge have been used. In addition to rule-based approaches [20,34,35] that are similar in nature to those discussed in Section 3.1, case-based reasoning has also been used. CBR is a general problem solving technique that uses specific knowledge of previous problems to solve new ones. In applying this approach to layout planning, a layout plan for a work piece is obtained by retrieving the plan used for a similar work piece from a case library containing knowledge of previous work pieces and their layout plans [18,36,37]. Work piece similarity is typically characterized through indexing work pieces according to their part family classification, tolerances, features, and so on. Lin and Huang [38] adopt a similar work piece classification approach, but retrieve layout plans using a neural network. Further work has sought to verify layout plans and repair them if necessary. For example Roy and Liao [39] perform a work piece deformation analysis and if deformation is too great employ heuristic rules to relocate and retest locating and clamping positions.3.2.3. Approaches to layout planning optimizationLayout plan optimization is common within CAFD and occurs with respect to work piece stability and deformation, which are both constraining requirements. Stability based optimization typically focuses upon ensuring a layout plan satisfies the kinematic form closure constraint (in which a set of contacts completely constrain infinitesimal part motion) and augmenting this with optimization against some form of stability based requirement, such as minimizing forces at the locating and/or clamping points [40–42] . Wu and Chan [43] focused on optimizing stability (measuring stability is discussed in Section 3.4) using a Genetic Algorithm (GA), which is a technique frequently employed in deformation based optimization.GAs, which are an example of evolutionary algorithms, are often used to solve optimization problems and draw their inspiration from biological evolution. Applying GAs in support of fixture planning, potential layout plan solutions are encoded as binary strings, tested, evaluated, and subjected to ‘‘biological’’ modification through reproduction, mutation, and crossover to generate improved solutions until an optimal state is reached. Typically deformation testing is employed using a finite element analysis in which a work piece is discretized to create a series of nodes that represent potential locating and clamping contact points, as performed for example by Kashyap and DeVries [44] . Sets of contact points are encoded and tested, and the GA used to develop new contact point sets until an optimum is reached that minimizes work piece deformation caused by machining and clamping forces [45,46]. Rather than use nodes, some CAFD approaches use geometric data (such as spatial coordinates) in the GA, which can offer improved accuracy as they account for the physical distance that exists between nodes [47,48].Pseudo gradient techniques [49] have also been employed to achieve optimization [50,51]. Vallapuzha et al. [52] compared the effectiveness of GA and pseudo gradient optimization, concluding that GAs provided higher quality optimizations given their ability to search for global solutions, whereas pseudo gradient techniques tended to converge on local optimums.Rather than concentrating on fixture designs for individual parts, Kong and Ceglarek [53] define a method that identifies the fixture workspace for a family of parts based on the individual configuration of the fixture locating layout for each part. The method uses Procrustes analysis to identify a preliminary workspace layout that is subjected to pairwise optimization of fixture configurations for a given part family to determine the best superposition of locating points for a family of parts that can be assembled on a single reconfigurable assembly fixture. This buildsupon earlier work by Lee et al. [54] through attempting to simplify the computational demands of the optimization algorithm.3.3. Unit designUnit design involves both the conceptual and detailed definition of the locating and clamping units of a fixture, together with the base plate to which they are attached (Fig. 5). These units consist of a locator or clamp that contacts the work piece and is itself attached to a structural support, which in turn connects with the base plate. These structural supports serve multiple functions, for example providing the locating and clamping units with sufficient rigidity such that the fixture can withstand applied machining and clamping forces and thus result in the part feature design tolerances being obtained, and allowing the clamp or locator to contact the work piece at the appropriate position. Unit design has in general received less attention than both fixture planning and verification, but a number of techniques have been applied to support both conceptual and detailed unit design.3.3.1. Approaches to conceptual unit designConceptual unit design has focused upon the definition of the types and numbers of elements that an individual unit should comprise, as well as their general layout. There are a wide variety of locators, clamps, and structural support elements, each of which can be more suited to some fixturing problems than others. As with both setup planning and fixture layout planning, rule-based approaches have been adopted to support conceptual unit design, in which heuristic rules are used to select preferred elements from which the units should be constructed in response to considerations such as work piece contact features (surface type, surface texture, etc.) and machining operations within the setup [35,55–58]. In addition to using heuristic rules as a means of generating conceptual designs, Kumar et al.[59] use an inductive reasoning technique to create decision trees from which such fixturing rules can be obtained through examination of each decision tree path.Neural network approaches have also been used to support conceptual unit design. Kumar et al. [60] use a combined GA/neural network approach in which a neural network is trained with a selection of previous design problems and their solutions. A GA generates possible solutionswhich are evaluated using the neural network, which subsequently guides the GA. Lin and Huang[38] also use a neural network in a simplified case-based reasoning (CBR) approach in which fixturing problems are coded in terms of their geometrical structure and a neural network used to find similar work pieces and their unit designs. In contrast, Wang and Rong[37] and Boyle et al.[31] use a conventional CBR approach to retrieve units in which the fixturing functional requirements form the basis of retrieval, which are then subject to refinement and/or modification during detailed unit design.3.3.2. Approaches to detailed unit designMany, but not all systems that perform conceptual design also perform detailed design, where the dominant techniques are rule, geometry, and behavior based. Detailed design involves the definition of the units in terms of their dimensions, material types, and so on. Geometry, in particular the acting height of locating and clamping units, plays a key role in the design of individual units in which the objective is to select and assemble defined unit elements to provide a unit of suitable acting height [61,62]. An et al. [63] developed a geometry based system in which the dimensions of individual elements were generated in relation to the primary dimension of that element (typically its required height) through parametric dimension relationships. This was augmented with a relationship knowledge base of how different elements could be configured to form a single unit. Similarly, Peng et al. [64] use geometric constraint reasoning to assist in the assembly of user selected elements to form individual units in a more interactive approach.Alternatively, rule-based approaches have also been used to define detailed units, in which work piece and fixture layout information (i.e., the locating and clamping positions) is reasoned over using design rules to select and assemble appropriately sized elements [32,55,56] . In contrast, Mervyn et al. [65] adopt an evolutionary algorithm approach to the development of units, in which layout planning and unit design take place concurrently until a satisfactory solution is reached.Typically, rule and geometry based approaches do not explicitly consider the required strength of units during their design. However for a fixture to achieve its function, it must be able to withstand the machining and clamping forces imposed upon it such that part design tolerances can be met. To address this, a number of behaviorally driven approaches to unit design have been developed that focus upon ensuring units have sufficient strength. Cecil [66] performed some preliminary work on dimensioning strap clamps to prevent failure by stress fracture, but does not consider tolerances or the supporting structural unit. Hurtado and Melkote [67] developed a model for the synthesis of fixturing configurations in simple pin-array type flexible machining fixtures, in which the minimum number of pins, their position, and dimensions are determined that can achieve stability and stiffness goals for a work piece through consideration of the fixture/work piece stiffness matrix, and extended this for modular fixtures [68] . Boyle et al. [31] also consider the required stiffness of more complex unit designs within their case-based reasoning method. Having retrieved a conceptual design that offers the correct type of function, this design’s physical structure is then adapted using dynamically selected adaptation strategies until it offers the correct level of stiffness.3.4. VerificationVerification focuses upon ensuring that developed fixture designs (in terms of their setup plans, layout plans, and physical units) satisfy the fixturing requirements. It should be noted from。
汽车焊接夹具设计外文文献翻译
汽车焊接夹具设计外文文献翻译(含：英文原文及中文译文)文献出处：Semjon Kim.Design of Automotive Welding Fixtures [J]. Computer-Aided Design, 2013, 3(12):21-32.英文原文Design of Automotive Welding FixturesSemjon Kim1 AbstractAccording to the design theory of car body welding fixture, the welding fixture and welding bus of each station are planned and designed. Then the fixture is modeled and assembled. The number and model of the fixture are determined and the accessibility is judged. Designed to meet the requirements of the welding fixture.Keywords: welded parts; foundation; clamping; position1 IntroductionAssembly and welding fixtures are closely related to the production of high-quality automotive equipment in automotive body assembly and welding lines. Welded fixtures are an important part of the welding process. Assembly and welding fixtures are not only the way to complete the assembly of parts in this process, but also as a test and calibration procedure on the production line to complete the task of testing welding accessories and welding quality. Therefore, the design and manufacture ofwelding fixtures directly affect the production capacity and product quality of the automobile in the welding process. Automotive welding fixtures are an important means of ensuring their manufacturing quality and shortening their manufacturing cycle. Therefore, it is indispensable to correctly understand the key points of welding fixture design, improve and increase the design means and design level of welding fixtures, and improve the adjustment and verification level of fixtures. It is also an auto manufacturing company in the fierce competition. The problem that must be solved to survive.The style of the car is different from that of the car. Therefore, the shape of the welding jig is very different. However, the design, manufacture, and adjustment are common and can be used for reference.2. Structural design of welding fixtureThe structure design of the welding fixture ensures that the clip has good operational convenience and reliable positioning of the fixture. Manufacturers of welding fixtures can also easily integrate adjustments to ensure that the surfaces of the various parts of the structure should allow enough room for adjustments to ensure three-dimensional adjustment. Of course, under the premise of ensuring the accuracy of the welding jig, the structure of the welding jig should be as simple as possible. The fixture design is usually the position of all components on the fixture is determined directly based on the design basis, and ultimately ensure thatthe qualified welding fixture structure is manufactured. According to the working height, the height of the fixture bottom plate can be preliminarily determined, that is, the height of the fixture fixing position. The welding fixture design must first consider the clamping method. There are two types, manual and pneumatic. Manual clamping is generally suitable for small parts, external parts, and small batches of workpieces. For large body parts, planning in the production line, automation High-demand welding fixtures should be pneumatically clamped. Automobile production is generally pneumatically clamped, and manual mass clamping can be used as auxiliary clamping. This can reduce costs accordingly. Some manual clamping products already have standard models and quantities, which can be purchased in the market when needed. For some devices, pneumatic clamping is specified, but if pneumatic clamping is used, the workpiece may be damaged. Therefore, it is possible to manually press the place first to provide a pneumatic clamping force to clamp the workpiece. This is manual-pneumatic. . The fixture clamping system is mounted on a large platform, all of which are fixed in this welding position to ensure that the welding conditions should meet the design dimensions of the workpiece coordinate system positioning fixture, which involves the benchmark.3. Benchmarks of assembly and welding fixtures and their chosen support surfaces3.1 Determination of design basisIn order to ensure that the three-dimensional coordinates of the automatic weldment system are consistent, all welding fixtures must have a common reference in the system. The benchmark is the fixture mounting platform. This is the X, Y coordinate, each specific component is fixed at the corresponding position on the platform, and has a corresponding height. Therefore, the Z coordinate should be coordinated, and a three-dimensional XYZ coordinate system is established. In order to facilitate the installation and measurement of the fixture, the mounting platform must have coordinates for reference. There are usually three types. The structure is as follows:3.1.1 Reference hole methodThere are four reference holes in the design of the installation platform, in which the two directions of the center coordinates of each hole and the coordinates of the four holes constitute two mutually perpendicular lines. This is the collection on the XY plane coordinate system. The establishment of this benchmark is relatively simple and easy to process, but the measurements and benchmarks used at the same time are accurate. Any shape is composed of spatial points. All geometric measurements can be attributed to measurements of spatial points. Accurate spatial coordinate acquisition is therefore the basis for assessing any geometric shape. Reference A coordinated direction formed by oneside near two datums.3.1.2 v-type detection methodIn this method, the mounting platform is divided into two 90-degree ranges. The lines of the two axes make up a plane-mounted platform. The plane is perpendicular to the platform. The surface forms of these two axis grooves XY plane coordinate system.3.1.3 Reference block methodReference Using the side block perpendicular to the 3D XYZ coordinate system, the base of a gage and 3 to 4 blocks can be mounted directly on the platform, or a bearing fixing fixture platform can be added, but the height of the reference plane must be used to control the height , must ensure the same direction. When manufacturing, it is more difficult to adjust the previous two methods of the block, but this kind of measurement is extremely convenient, especially using the CMM measurement. This method requires a relatively low surface mount platform for the reference block, so a larger sized mounting platform should use this method.Each fixture must have a fixed coordinate system. In this coordinate system, its supporting base coordinate dimensions should support the workpiece and the coordinates correspond to the same size. So the choice of bearing surface in the whole welding fixture system 3.2When the bearing surface is selected, the angle between the tangentplane and the mounting platform on the fixed surface of the welding test piece shall not be greater than 15 degrees. The inspection surface should be the same as the welded pipe fittings as much as possible for the convenience of flat surface treatment and adjustment. The surface structure of the bearing should be designed so that the module can be easily handled, and this number can be used for the numerical control of the bearing surface of the product. Of course, designing the vehicle body coordinate point is not necessarily suitable for the bearing surface, especially the NC fixture. This requires the support of the fixture to block the access point S, based on which the digital surface is established. This surface should be consistent with the supported surface. So at this time, it is easier and easier to manufacture the base point S, CNC machining, precision machining and assembly and debugging.3.2 Basic requirements for welding fixtureIn the process of automobile assembly and production, there are certain requirements for the fixture. First, according to the design of the automobile and the requirements of the welding process, the shape, size and precision of the fixture have reached the design requirements and technical requirements. This is a link that can not be ignored, and the first consideration in the design of welding fixture is considered. When assembling, the parts or parts of the assembly should be consistent with the position of the design drawings of the car and tighten with the fixture.At the same time, the position should be adjusted to ensure that the position of the assembly parts is clamped accurately so as to avoid the deformation or movement of the parts during the welding. Therefore, this puts forward higher requirements for welding jig. In order to ensure the smooth process of automobile welding and improve the production efficiency and economic benefit, the workers operate conveniently, reduce the strength of the welder's work, ensure the precision of the automobile assembly and improve the quality of the automobile production. Therefore, when the fixture design is designed, the design structure should be relatively simple, it has good operability, it is relatively easy to make and maintain, and the replacement of fixture parts is more convenient when the fixture parts are damaged, and the cost is relatively economical and reasonable. But the welding fixture must meet the construction technology requirements. When the fixture is welded, the structure of the fixture should be open so that the welding equipment is easy to close to the working position, which reduces the labor intensity of the workers and improves the production efficiency.4. Position the workpieceThe general position of the workpiece surface features is determined relative to the hole or the apparent positioning reference surface. It is commonly used as a locating pin assembly. It is divided into two parts: clamping positioning and fixed positioning. Taking into account thewelding position and all welding equipment, it is not possible to influence the removal of the final weld, but also to allow the welding clamp or torch to reach the welding position. For truly influential positioning pins and the like, consider using movable positioning pins. In order to facilitate the entry and exit of parts, telescopic positioning pins are available. The specific structure can be found in the manual. The installation of welding fixtures should be convenient for construction, and there should be enough space for assembly and welding. It must not affect the welding operation and the welder's observation, and it does not hinder the loading and unloading of the weldment. All positioning elements and clamping mechanisms should be kept at a proper distance from the solder joints or be placed under or on the surface of the weldment. The actuator of the clamping mechanism should be able to flex or index. According to the formation principle, the workpiece is clamped and positioned. Then open the fixture to remove the workpiece. Make sure the fixture does not interfere with opening and closing. In order to reduce the auxiliary time for loading and unloading workpieces, the clamping device should use high-efficiency and quick devices and multi-point linkage mechanisms. For thin-plate stampings, the point of application of the clamping force should act on the bearing surface. Only parts that are very rigid can be allowed to act in the plane formed by several bearing points so that the clamping force does not bend the workpiece or deviate from thepositioning reference. In addition, it must be designed so that it does not pinch the hand when the clamping mechanism is clamped to open.5. Work station mobilization of welding partsMost automotive solder fittings are soldered to complete in several processes. Therefore, it needs a transmission device. Usually the workpiece should avoid the interference of the welding fixture before transmission. The first step is to lift the workpiece. This requires the use of an elevator, a crane, a rack and pinion, etc. The racks and gears at this time Structure, their structural processing, connection is not as simple as the completion of the structure of the transmission between the usual connection structure of the station, there are several forms, such as gears, rack drive mechanism, transmission mechanism, rocker mechanism, due to the reciprocating motion, shake The transfer of the arm mechanism to the commissioning is better than the other one, so the common rocker arm transfer mechanism is generally used.6 ConclusionIn recent years, how to correctly and reasonably set the auxiliary positioning support for automotive welding fixtures is an extremely complicated system problem. Although we have accumulated some experience in this area, there is still much to be learned in this field. Learn and research to provide new theoretical support for continuous development and innovation in the field of welding fixture design. Withthe development of the Chinese automotive industry, more and more welding fixtures are needed. Although the principle of the fixture is very simple, the real design and manufacture of a high-quality welding fixture system is an extremely complicated project.中文译文汽车焊接夹具的设计Semjon Kim1摘要依据车体焊装线夹具设计理论, 对各工位焊接夹具及其焊装总线进行规划、设计, 之后进行夹具建模、装配, 插入焊钳确定其数量、型号及判断其可达性,最终设计出符合要求的焊接夹具。
夹具设计外文翻译
Application and developmentOf case based reasoning in fixture designFixtures are devices that serve as the purpose of holding the workpiece securely and accurately, and maintaining a consistent relationship with respect to the tools while machining. Because the fixture structure depends on the feature of the product and the status of the process planning in the enterprise, its design is the bottleneck during manufacturing, which restrains to improve the efficiency and leadtime. And fixture design is a complicated process, based on experience that needs comprehensive qualitative knowledge about a number of design issues including workpiece configuration, manufacturing processes involved, and machining environment. This is also a very time consuming work when using traditional CAD tools (such as Unigraphics, CATIA or Pro/E), which are good at performing detailed design tasks, but provide few benefits for taking advantage of the previous design experience and resources, which are precisely the key factors in improving the efficiency. The methodology of case based reasoning (CBR) adapts the solution of a previously solved case to build a solution for a new problem with the following four steps: retrieve, reuse, revise, and retain [1]. This is a more useful method than the use of an expert system to simulate human thought because proposing a similar case and applying a few modifications seems to be self explanatory and more intuitive to humans .So various case based design support tools have been developed for numerous areas[2-4], such as in injection molding and design, architectural design, die casting die design, process planning, and also in fixture design. Sun used six digitals to compose the index code that included workpiece shape, machine portion, bushing, the 1st locating device, the 2nd locating device and clamping device[5]. But the system cannot be used for other fixture types except for drill fixtures, and cannot solve the problem of storage of the same index code that needs to be retained, which is very important in CBR[6].1. Construction of a Case Index and Case Library1.1 Case indexThe case index should be composed of all features of the workpiece, which are distinguished from different fixtures. Using all of them would make the operation in convenient. Because the forms of the parts are diverse, and the technology requirements of manufacture in the enterprise also develop continuously, lots of features used as the case index will make the search rate slow, and the main feature unimportant, for the reason that the relative weight which is allotted to every feature must diminish. And on the other hand, it is hard to include all the features in the case index.1.2 Hierarchical form of CaseThe structure similarity of the fixture is represented as the whole fixture similarity, components similarity and component similarity. So the whole fixture case library, components case library, component case library of fixture are formedcorrespondingly. Usually design information of the whole fixture is composed of workpiece information and workpiece procedure information, which represent the fixture satisfying the specifically designing function demand. The whole fixture case is made up of function components, which are described by the function components’ names and numbers. The components case represents the members. (function component and other structure components，main driven parameter, the number, and their constrain relations.) The component case (the lowest layer of the fixture) is the structure of function component and other components. In the modern fixture design there are lots of parametric standard parts and common non standard parts. So the component case library should record the specification parameter and the way in which it keeps them.2. Strategy of Case RetrievalIn the case based design of fixtures ,the most important thing is the retrieval of the similarity, which can help to obtain the most similar case, and to cut down the time of adaptation. According to the requirement of fixture design, the strategy of case retrieval combines the way of the nearest neighbor and knowledge guided. That is, first search on depth, then on breadth; the knowledge guided strategy means to search on the knowledge rule from root to the object, which is firstly searched by the fixture type, then by the shape of the workpiece, thirdly by the locating method. For example, if the case index code includes the milling fixture of fixture type, the search is just for all milling fixtures, then for box of workpiece shape, the third for 1plane+ 2pine of locating method. If there is no match of it, then the search stops on depth, and returns to the upper layer, and retrieves all the relative cases on breadth.2.1 Case adaptationThe modification of the analogical case in the fixture design includes the following three cases:1) The substitution of components and the component;2) Adjusting the dimension of components and the component while the form remains;3) The redesign of the model.If the components and component of the fixture are common objects, they can be edited, substituted and deleted with tools, which have been designed.2.2 Case storageBefore saving a new fixture case in the case library, the designer must consider whether the saving is valuable. If the case does not increase the knowledge of the system, it is not necessary to store it in the case library. If it is valuable, then the designer must analyze it before saving it to see whether the case is stored as a prototype case or as reference case. A prototype case is a representation that can describe the main features of a case family. A case family consists of those cases whose index codes have the same first 13 digits and different last three digits in the case library. The last three digits of a prototype case are always “000”. A reference case belongs to the same family as the prototype case and is distinguished by the different last three digits.From the concept that has been explained, the following strategies are adopted:1) If a new case matches any existing case family, it has the same first 13 digits as an existing prototype case, so the case is not saved because it is represented well by the prototype case. Or is just saved as a reference case (the last 3 digits are not “000”, and not the same with others) in the case library.2) If a new case matches any existing case family and is thought to be better at representing this case family than the previous prototype case, then the prototype case is substituted by this new case, and the previous prototype case is saved as a reference case.3) If a new case does not match any existing case family, a new case family will be generated automatically and the case is stored as the prototype case in the case library.3. ConclusionCBR, as a problem solving methodology, is a more efficient method than an expert system to simulate human thought, and has been developed in many domains where knowledge is difficult to acquire. The advantages of the CBR are as follows: it resembles human thought more closely; the building of a case library which has self learning ability by saving new cases is easier and faster than the building of a rule library; and it supports a better transfer and explanation of new knowledge that is more different than the rule library. A proposed fixture design framework on the CBR has been implemented by using Visual C ++, UG/Open API in U n graphics with Oracle as database support, which also has been integrated with the 32D parametric common component library, common components library and typical fixture library. The prototype system, developed here, is used for the aviation project, and aids the fixture designers to improve the design efficiency and reuse previous design resources.基于事例推理的夹具设计研究与应用夹具是以确定工件安全定位准确为目的的装置，并在加工过程中保持工件与刀具或机床的位置一致不变。
夹具设计英文文献
A review and analysis of current computer-aided fixture design approachesIain Boyle, Yiming Rong, David C. BrownKeywords:Computer-aided fixture designFixture designFixture planningFixture verificationSetup planningUnit designABSTRACTA key characteristic of the modern market place is the consumer demand for variety. To respond effectively to this demand, manufacturers need to ensure that their manufacturing practices are sufficiently flexible to allow them to achieve rapid product development. Fixturing, which involves using fixtures to secure work pieces during machining so that they can be transformed into parts that meet required design specifications, is a significant contributing factor towards achieving manufacturing flexibility. To enable flexible fixturing, considerable levels of research effort have been devoted to supporting the process of fixture design through the development of computer-aided fixture design (CAFD) tools and approaches. This paper contains a review of these research efforts. Over seventy-five CAFD tools and approaches are reviewed in terms of the fixture design phases they support and the underlying technology upon which they are based. The primary conclusion of the review is that while significant advances have been made in supporting fixture design, there are primarily two research issues that require further effort. The first of these is that current CAFD research is segmented in nature and there remains a need to provide more cohesive fixture design support. Secondly, a greater focus is required on supporting the detailed design of a fixture’s physical structure.2010 Elsevier Ltd. All rights reserved. Contents1. Introduction (2)2. Fixture design (2)3. Current CAFD approaches (4)3.1 Setup planning (4)3.1.1 Approaches to setup planning (4)3.2 Fixture planning (4)3.2.1 Approaches to defining the fixturing requirement (6)3.2.2 Approaches to non-optimized layout planning (6)3.2.3 Approaches to layout planning optimization (6)3.3 Unit design (7)3.3.1 Approaches to conceptual unit design (7)3.3.2 Approaches to detailed unit design (7)3.4 Verification (8)3.4.1 Approaches to constraining requirements verification (8)3.4.2 Approaches to tolerance requirements verification (8)3.4.3 Approaches to collision detection requirements verification (8)3.4.4 Approaches to usability and affordability requirements verification (9)3.5 Representation of fixturing information (9)4. An analysis of CAFD research (9)4.1 The segmented nature of CAFD research (9)4.2 Effectively supporting unit design (10)4.3 Comprehensively formulating the fixturing requirement (10)4.4 Validating CAFD research outputs (10)5. Conclusion (10)References (10)1. IntroductionA key concern for manufacturing companies is developing the ability to design and produce a variety of high quality products within short timeframes. Quick release of a new product into the market place, ahead of any competitors, is a crucial factor in being able to secure a higher percentage of the market place and increased profit margin. As a result of the consumer desire for variety, batch production of products is now more the norm than mass production, which has resulted in the need for manufacturers to develop flexible manufacturing practices to achieve a rapid turnaround in product development.A number of factors contribute to an organization’s ability to achieve flexible manufacturing, one of which is the use of fixtures during production in which work pieces go through a number of machining operations to produce individual parts which are subsequently assembled into products. Fixtures are used to rapidly, accurately, and securely position work pieces during machining such that all machined parts fall within the design specifications for that part. This accuracy facilitates the interchangeability of parts that is prevalent in much of modern manufacturing where many different products feature common parts.The costs associated with fixturing can account for 10–20% of the total cost of a manufacturing system [1]. These costs relate not only to fixture manufacture, assembly, and operation, but also to their design. Hence there are significant benefits to be reaped by reducing the design costs associated with fixturing and two approaches have been adopted in pursuit of this aim. One has concentrated on developing flexible fixturing systems, such as the use of phase-changing materials to hold work pieces in place [2] and the development of commercial modular fixture systems. However, the significant limitation of the flexible fixturing mantra is that it does not address the difficulty of designing fixtures. To combat this problem, a second research approach has been to develop computer-aided fixture design (CAFD) systems that support and simplify the fixture design process and it is this research that is reviewed within this paper.Section 2 describes the principal phases of and the wide variety of requirements driving the fixture design process. Subsequently in Section 3 an overview of research efforts that havefocused upon the development of techniques and tools for supporting these individual phases of the design process is provided. Section 4 critiques these efforts to identify current gaps in CAFD research, and finally the paper concludes by offering some potential directions for future CAFD research. Before proceeding, it is worth noting that there have been previous reviews of fixturing research, most recently Bi and Zhang [1] and Pehlivan and Summers [3]. Bi and Zhang, while providing some details on CAFD research, tend to focus upon the development of flexible fixturing systems, and Pehlivan and Summers focus upon information integration within fixture design. The value of this paper is that it provides an in-depth review and critique of current CAFD techniques and tools and how they provide support across the entire fixture design process.2. Fixture designThis section outlines the main features of fixtures and more pertinently of the fixture design process against which research efforts will be reviewed and critiqued in Sections 3 and 4, respectively. Physically a fixture consists of devices that support and clamp a work piece [4,5]. Fig.1 represents a typical example of a fixture in which the work piece rests on locators that accurately locate it. Clamps hold the work piece against the locators during machining thus securing the work piece’s location. The locating units themselves consist of the locator supporting unit and the locator that contacts the work piece. The clamping units consist of a clamp supporting unit and a clamp that contacts the work piece and exerts a clamping force to restrain it.Typically the design process by which such fixtures are created has four phases: setup planning, fixture planning, unit design, and verification, as illustrated in Fig. 2 , which is adapted from Kang et al. [6]. During setup planning work piece and machining information is analyzed to determine the number of setups required to perform all necessary machining operations and the appropriate locating datums for each setup. A setup represents the combination of processes that can be performed on a work piece without having to alter the position or orientation of the work piece manually. To generate a fixture for each setup the fixture planning, unit design, and verification phases are executed.During fixture planning, the fixturing requirements for a setup are generated and the layout plan, which represents the first step towards a solution to these requirements is generated. This layout plan details the work piece surfaces with which the fixture’s locating and clamping units will establish contact, together with the surface positions of the locating and clamping points. The number and position of locating points must be such that a work piece’s six degrees of freedom (Fig. 3 ) are adequately constrained during machining [7] and there are a variety of conceptual locating point layouts that can facilitate this, such as the 3-2-1 locating principle [4]. In the third phase, suitable unit designs (i.e., the locating and clamping units) are generated and the fixture is subsequently tested during the verification phase to ensure that it satisfies the fixturing requirements driving the design process. It is worth noting that verification of setups and fixture plans can take place as they are generated and prior to unit design.Fixturing requirements, which although not shown in Kang et al.[6] are typically generated during the fixture planning phase, can be grouped into six class es ( Table 1 ). The ‘‘physical’’requirements class is the most basic and relates to ensuring the fixture can physically support the work piece. The ‘‘tolerance’’requirements relate to ensuring that the locating tolerances aresufficient to locate the work piece accurately and similarly the‘‘constraining’’ requirements focus on maintaining this accuracy as the work piece and fixture are subjected to machining forces. The ‘‘affordability’’ requirements relate to ensuring the fixture represents value, for example in terms of material, operating, and assembly/disassembly costs.The ‘‘collision detection’’ requirements focus upon ensuring that the fixture does not collide with the machining path, the work piece, or indeed itself. The ‘‘usability’’ requirements relate to fixture ergonomics and include for example needs related to ensuring that a fixture features error-proofing to prevent incorrect insertion of a work piece, and chip shedding, where the fixture assists in the removal of machined chips from the work piece.As with many design situations, the conflicting nature of these requirements is problematic. For example a heavy fixture can be advantageous in terms of stability but can adversely affect cost (due to increased material costs) and usability (because the increased weight may hinder manual handling). Such conflicts add to the complexity of fixture design and contribute to the need for the CAFD research reviewed in Section 3.Table 1Fixturing requirements.Generic requirement Abstract sub-requirement examplesPhysical ●The fixture must be physically capable of accommodatingthe work piece geometry and weight.●The fixture must allow access to the work piece features tobe machined.Toleranc e ●The fixture locating tolerances should be sufficient to satisfypart design tolerances.Constraining●The fixture shall ensure work piece stability (i.e., ensure thatwork piece force and moment equilibrium are maintained).●The fixture shall ensure that the fixture/work piece stiffness issufficient to prevent deformation from occurring that could resultin design tolerances not being achieved.Affordabilit y ●The fixture cost shall not exceed desired levels.●The fixture assembly/disassembly times shall not exceeddesired levels.●The fixture operation time shall not exceed desired levels. CollisionPrevention●The fixture shall not cause tool path–fixture collisions to occur.●The fixture shall cause work piece–fixture collisions to occur(other than at the designated locating and clamping positions).●The fixture shall not cause fixture–fixture collisions to occur(other than at the designated fixture component connectionpoints).Usabilit y ●The fixture weight shall not exceed desired levels.●The fixture shall not cause surface damage at the workpiece/fixture interface.●The fixture shall provide tool guidance to designated workpiece features.●The fixture shall ensure error-proofing (i.e., the fixture shouldprevent incorrect insertion of the work piece into the fixture).●The fixture shall facilitate chip shedding (i.e., the fixture shouldprovide a means for allowing machined chips to flow awayfrom the work piece and fixture).3. Current CAFD approachesThis section describes current CAFD research efforts, focusing on the manner in which they support the four phases of fixture design. Table 2 provides a summary of research efforts based upon the design phases they support, the fixture requirements they seek to address (boldtext highlights that the requirement is addressed to a significant degree of depth, whilst normal text that the degree of depth is lesser in nature), and the underlying technology upon which they are primarily based. Sections 3.1–3.4 describes different approaches for supporting setup planning, fixture planning, unit design, and verification, respectively. In addition, Section 3.5 discusses CAFD research efforts with regard to representing fixturing information.3.1. Setup planningSetup planning involves the identification of machining setups, where an individual setup defines the features that can be machined on a work piece without having to alter the position or orientation of the work piece manually. Thereafter, the remaining phases of the design process focus on developing individual fixtures for each setup that secure the work piece. From a fixturing viewpoint, the key outputs from the setup planning stage are the identification of each required setup and the locating datums (i.e., the primary surfaces that will be used to locate the work piece in the fixture).The key task within setup planning is the grouping or clustering of features that can be machined within a single setup. Machining features can be defined as the volume swept by a cutting tool, and typical examples include holes, slots, surfaces, and pockets [8]. Clustering of these features into individual setups is dependent upon a number of factors (including the tolerance dependencies between features, the capability of the machine tools that will be used to create the features, the direction of the cutting tool approach, and the feature machining precedence order), and a number of techniques have been developed to support setup planning. Graph theory and heuristic reasoning are the most common techniques used to support setup planning, although matrix based techniques and neural networks have also been employed.3.1.1. Approaches to setup planningThe use of graph theory to determine and represent setups has been a particularly popular approach [9–11]. Graphs consist of two sets of elements: vertices, which represent work piece features, and edges, which represent the relationships that exist between features and drive setup identification. Their nature can vary, for example in Sarma and Wright [9] consideration of feature machining precedence relationships is prominent, whereas Huang and Zhang [10] focus upon thetolerance relationships that exist between features. Given that these edges can be weighted in accordance with the tolerance magnitudes, this graph approach can also facilitate the identification of setups that can minimize tolerance stack up errors between setups through the grouping of tight tolerances. However, this can prove problematic given the difficulty of comparing the magnitude of different tolerance types to each other thus Huang [12] includes the use of tolerance factors [13] as a means of facilitating such comparisons, which are refined and extended by Huang and Liu [14] to cater for a greater variety of tolerance types and the case of multiple tolerance requirements being associated with the same set of features.While some methods use undirected graphs to assist setup identification [11] , Yao et al. [15] , Zhang and Lin [16] , and Zhang et al. [17] use directed graphs that facilitate the determination and explicit representation of which features should be used as locating datums ( Fig. 4 ) in addition to setup identification and sequencing. Also, Yao et al. refine the identified setups through consideration of available machine tool capability in a two stage setup planning process.Experiential knowledge, in the form of heuristic reasoning, has also been used to assist setup planning. Its popularity stems from the fact that fixture design effectiveness has been considered to be dependent upon the experience of the fixture designer [18] .To support setup planning, such knowledge has typically been held in the form of empirically derived heuristic rules, although object oriented approaches have on occasion been adopted [19] . For example Gologlu [20] uses heuristic rules together with geometric reasoning to support feature clustering, feature machining precedence, and locating datum selection. Within such heuristic approaches, the focus tends to fall upon rules concerning the physical nature of features and machining processes used to create them [21, 22]. Although some techniques do include feature tolerance considerations [23], their depth of analysis can be less than that found within the graph based techniques [24]. Similarly, kinematic approaches [25] have been used to facilitate a deeper analysis of the impact of tool approach directions upon feature clustering than is typically achieved using rule-based approaches. However, it is worth noting that graph based approaches are often augmented with experiential rule-bases to increase their overall effectiveness [16] .Matrix based approaches have also been used to support setup planning, in which a matrix defining feature clusters is generated and subsequently refined. Ong et al. [26] determine a feature precedence matrix outlining the order in which features can be machined, which is then optimized against a number of cost indicators (such as machine tool cost, change over time, etc.) in a hybrid genetic algorithm-simulated annealing approach through consideration of dynamically changing machine tool capabilities. Hebbal and Mehta [27] generate an initial feature grouping matrix based upon the machine tool approach direction for each feature which is subsequently refined through the application of algorithms that consider locating faces and feature tolerances.Alternatively, the use of neural networks to support setup planning has also been investigated. Neural networks are interconnected networks of simple elements, where the interconnections are ‘‘learned’’ from a set of example data. Once educated, these networks can generate solutions for new problems fed into the network. Ming and Mak [28] use a neural network approach in which feature precedence, tool approach direction, and tolerance relationships are fed into a Kohonen self-organizing neural network to group operations for individual features into setups.3.2. Fixture planningFixture planning involves the comprehensive definition of a fixturing requirement in terms ofthe physical, tolerance, constraining, affordability, collision prevention, and usability requirements listed in Table 1 , and the creation of a fixture layout plan. The layout plan represents the first part of the fixture solution to these requirements, and specifies the position of the locating and clamping points on the work piece. Many layout planning approaches feature verification, particularly with regard to the constraining requirements. Typically this verification forms part of a feedback loop that seeks to optimize the layout plan with respect to these requirements. Techniques used to support fixture planning are now discussed with respect to fixture requirement definition, layout planning, and layout optimization.Fig. 4. A work piece (a) and its directed graphs showing the locating datums (b) (adapted from Zhang et al. [17] ).3.2.1. Approaches to defining the fixturing requirementComprehensive fixture requirement definition has received limited attention, primarily focusing upon the definition of individual requirements within the physical, tolerance, and constraining requirements. For example, Zhang et al. [17] under-take tolerance requirement definition through an analysis of work piece feature tolerances to determine the allowed tolerance at each locating point and the decomposition of that tolerance into its sources. The allowed locating point accuracy is composed of a number of factors, such as the locating unit tolerance, the machine tool tolerance, the work piece deformation at the locating point, and so on. These decomposed tolerance requirements can subsequently drive fixture design: e.g., the tolerance of the locating unit developed in the unit design phase cannot exceed the specified locating unit tolerance. In a similar individualistic vein, definition of the clamping force requirements that clamping units must achieve has also received attention [29,30].In a more holistic approach, Boyle et al. [31] facilitate a comprehensive requirement specification through the use of skeleton requirement sets that provide an initial decomposition of the requirements listed in Table 1, and which are subsequently refined through a series of analyses and interaction with the fixture designer. Hunter et al. [32,33] also focus on functional requirement driven fixture design, but restrict their focus primarily to the physical and constraining requirements.3.2.2. Approaches to non-optimized layout planningLayout planning is concerned with the identification of the locating principle, which defines the number and general arrangement of locating and clamping points, the work piece surfaces they contact, and the surface coordinate positions where contact occurs. For non-optimized layoutplanning, approaches based upon the re-use of experiential knowledge have been used. In addition to rule-based approaches [20,34,35] that are similar in nature to those discussed in Section 3.1, case-based reasoning has also been used. CBR is a general problem solving technique that uses specific knowledge of previous problems to solve new ones. In applying this approach to layout planning, a layout plan for a work piece is obtained by retrieving the plan used for a similar work piece from a case library containing knowledge of previous work pieces and their layout plans [18,36,37]. Work piece similarity is typically characterized through indexing work pieces according to their part family classification, tolerances, features, and so on. Lin and Huang [38] adopt a similar work piece classification approach, but retrieve layout plans using a neural network. Further work has sought to verify layout plans and repair them if necessary. For example Roy and Liao [39] perform a work piece deformation analysis and if deformation is too great employ heuristic rules to relocate and retest locating and clamping positions.3.2.3. Approaches to layout planning optimizationLayout plan optimization is common within CAFD and occurs with respect to work piece stability and deformation, which are both constraining requirements. Stability based optimization typically focuses upon ensuring a layout plan satisfies the kinematic form closure constraint (in which a set of contacts completely constrain infinitesimal part motion) and augmenting this with optimization against some form of stability based requirement, such as minimizing forces at the locating and/or clamping points [40–42] . Wu and Chan [43] focused on optimizing stability (measuring stability is discussed in Section 3.4) using a Genetic Algorithm (GA), which is a technique frequently employed in deformation based optimization.GAs, which are an example of evolutionary algorithms, are often used to solve optimization problems and draw their inspiration from biological evolution. Applying GAs in support of fixture planning, potential layout plan solutions are encoded as binary strings, tested, evaluated, and subjected to ‘‘biological’’ modification through reproduction, mutation, and crossover to generate improved solutions until an optimal state is reached. Typically deformation testing is employed using a finite element analysis in which a work piece is discretized to create a series of nodes that represent potential locating and clamping contact points, as performed for example by Kashyap and DeVries [44] . Sets of contact points are encoded and tested, and the GA used to develop new contact point sets until an optimum is reached that minimizes work piece deformation caused by machining and clamping forces [45,46]. Rather than use nodes, some CAFD approaches use geometric data (such as spatial coordinates) in the GA, which can offer improved accuracy as they account for the physical distance that exists between nodes [47,48].Pseudo gradient techniques [49] have also been employed to achieve optimization [50,51]. Vallapuzha et al. [52] compared the effectiveness of GA and pseudo gradient optimization, concluding that GAs provided higher quality optimizations given their ability to search for global solutions, whereas pseudo gradient techniques tended to converge on local optimums.Rather than concentrating on fixture designs for individual parts, Kong and Ceglarek [53] define a method that identifies the fixture workspace for a family of parts based on the individual configuration of the fixture locating layout for each part. The method uses Procrustes analysis to identify a preliminary workspace layout that is subjected to pairwise optimization of fixture configurations for a given part family to determine the best superposition of locating points for a family of parts that can be assembled on a single reconfigurable assembly fixture. This buildsupon earlier work by Lee et al. [54] through attempting to simplify the computational demands of the optimization algorithm.3.3. Unit designUnit design involves both the conceptual and detailed definition of the locating and clamping units of a fixture, together with the base plate to which they are attached (Fig. 5). These units consist of a locator or clamp that contacts the work piece and is itself attached to a structural support, which in turn connects with the base plate. These structural supports serve multiple functions, for example providing the locating and clamping units with sufficient rigidity such that the fixture can withstand applied machining and clamping forces and thus result in the part feature design tolerances being obtained, and allowing the clamp or locator to contact the work piece at the appropriate position. Unit design has in general received less attention than both fixture planning and verification, but a number of techniques have been applied to support both conceptual and detailed unit design.3.3.1. Approaches to conceptual unit designConceptual unit design has focused upon the definition of the types and numbers of elements that an individual unit should comprise, as well as their general layout. There are a wide variety of locators, clamps, and structural support elements, each of which can be more suited to some fixturing problems than others. As with both setup planning and fixture layout planning, rule-based approaches have been adopted to support conceptual unit design, in which heuristic rules are used to select preferred elements from which the units should be constructed in response to considerations such as work piece contact features (surface type, surface texture, etc.) and machining operations within the setup [35,55–58]. In addition to using heuristic rules as a means of generating conceptual designs, Kumar et al.[59] use an inductive reasoning technique to create decision trees from which such fixturing rules can be obtained through examination of each decision tree path.Neural network approaches have also been used to support conceptual unit design. Kumar et al. [60] use a combined GA/neural network approach in which a neural network is trained with a selection of previous design problems and their solutions. A GA generates possible solutionswhich are evaluated using the neural network, which subsequently guides the GA. Lin and Huang[38] also use a neural network in a simplified case-based reasoning (CBR) approach in which fixturing problems are coded in terms of their geometrical structure and a neural network used to find similar work pieces and their unit designs. In contrast, Wang and Rong[37] and Boyle et al.[31] use a conventional CBR approach to retrieve units in which the fixturing functional requirements form the basis of retrieval, which are then subject to refinement and/or modification during detailed unit design.3.3.2. Approaches to detailed unit designMany, but not all systems that perform conceptual design also perform detailed design, where the dominant techniques are rule, geometry, and behavior based. Detailed design involves the definition of the units in terms of their dimensions, material types, and so on. Geometry, in particular the acting height of locating and clamping units, plays a key role in the design of individual units in which the objective is to select and assemble defined unit elements to provide a unit of suitable acting height [61,62]. An et al. [63] developed a geometry based system in which the dimensions of individual elements were generated in relation to the primary dimension of that element (typically its required height) through parametric dimension relationships. This was augmented with a relationship knowledge base of how different elements could be configured to form a single unit. Similarly, Peng et al. [64] use geometric constraint reasoning to assist in the assembly of user selected elements to form individual units in a more interactive approach.Alternatively, rule-based approaches have also been used to define detailed units, in which work piece and fixture layout information (i.e., the locating and clamping positions) is reasoned over using design rules to select and assemble appropriately sized elements [32,55,56] . In contrast, Mervyn et al. [65] adopt an evolutionary algorithm approach to the development of units, in which layout planning and unit design take place concurrently until a satisfactory solution is reached.Typically, rule and geometry based approaches do not explicitly consider the required strength of units during their design. However for a fixture to achieve its function, it must be able to withstand the machining and clamping forces imposed upon it such that part design tolerances can be met. To address this, a number of behaviorally driven approaches to unit design have been developed that focus upon ensuring units have sufficient strength. Cecil [66] performed some preliminary work on dimensioning strap clamps to prevent failure by stress fracture, but does not consider tolerances or the supporting structural unit. Hurtado and Melkote [67] developed a model for the synthesis of fixturing configurations in simple pin-array type flexible machining fixtures, in which the minimum number of pins, their position, and dimensions are determined that can achieve stability and stiffness goals for a work piece through consideration of the fixture/work piece stiffness matrix, and extended this for modular fixtures [68] . Boyle et al. [31] also consider the required stiffness of more complex unit designs within their case-based reasoning method. Having retrieved a conceptual design that offers the correct type of function, this design’s physical structure is then adapted using dynamically selected adaptation strategies until it offers the correct level of stiffness.3.4. VerificationVerification focuses upon ensuring that developed fixture designs (in terms of their setup plans, layout plans, and physical units) satisfy the fixturing requirements. It should be noted from。
车床和铣床机械加工工艺夹具装备外文文献翻译、中英文翻译、外文翻译
机械设计制造及自动化专业毕业设计（论文）外文翻译附录二LATHES & MILLINGA shop that is equipped with a milling machine and an engine lathe can machine almost any type of product of suitable size.The basic machines that are designed primarily to do turning，facing and boring are called lathes. Very little turning is done on other types of machine tools，and none can do it with equal facility. Because lathe can do boring，facing，drilling，and reaming in addition to turning，their versatility permits several operations to be performed with a single setup of the workpiece. This accounts for the fact that lathes of various types are more widely used in manufacturing than any other machine tool.Lathes in various forms have existed for more than two thousand years. Modern lathes date from about 1797，when Henry Maudsley developed one with a leads crew. It provided controlled，mechanical feed of the tool. This ingenious Englishman also developed a change gear system that could connect the motions of the spindle and leadscrew and thus enable threads to be cut.Lathe Construction.The essential components of a lathe are depicted in the block diagram of picture. These are the bed，headstock assembly，tailstock assembly，carriage assembly，quick-change gearbox，and the leadscrew and feed rod.The bed is the back bone of a lathe. It usually is made of well-normalized or aged gray or nodular cast iron and provides a heavy，rigid frame on which all the other basic components are mounted. Two sets of parallel，longitudinal ways，inner and outer，are contained on the bed，usually on the upper side. Some makers use an inverted V-shape for all four ways，whereas others utilize one inverted V and one flat way in one or both sets. Because several other components are mounted and/or move on the ways they must be made with precision to assure accuracy of alignment. Similarly，proper precaution should betaken in operating a lathe to assure that the ways are not damaged. Any inaccuracy in them usually means that the accuracy of the entire lathe is destroyed. The ways on most modern lathes are surface hardened to offer greater resistance to wear and abrasion.The headstock is mounted in a fixed position on the inner ways at one end of the lathe bed. It provides a powered means of rotating the work at various speeds. It consists，essentially，of a hollow spindle，mounted in accurate bearings，and a set of transmission gears——similar to a truck transmission——through which the spindle can be rotated at a number of speeds. Most lathes provide from eight to eighteen speeds，usually in a geometric ratio，and on modern lathes all the speeds can be obtained merely by moving from two to four levers. An increasing trend is to provide a continuously variable speed range through electrical or mechanical drives.Because the accuracy of a lathe is greatly dependent on the spindle，it is of heavy construction and mounted in heavy bearings，usually preloaded tapered roller or ball types. Along- itudinal hole extends through the spindle so that long bar stock can be fed through it. The size of this hole is an important size dimension of a lathe because it determines the maximum size of bar stock that can be machined when the material must be fed through the spindle.The inner end of the spindle protrudes from the gear box and contains a means for mounting various types of chucks，face plates，and dog plates on it. Whereas small lathes often employ a threaded section to which the chucks are screwed，most large lathes utilize either cam-lock or key-drive taper noses. These provide a large-diameter taper that assures the accurate alignment of the chuck，and a mechanism that permits the chuck or face plate to be locked or unlocked in position without the necessity of having to rotate these heavy attachments.Power is supplied to the spindle by means of an electric motor through a V-belt or silent-chain drive. Most modern lathes have motors of from 5 to15 horsepower to provide adequate power for carbide and ceramic tools at their high cutting speeds.The tailstock assembly consists，essentially，of three parts. A lower casting fits on the inner ways of the bed and can slide longitudinally thereon，with a means for clamping the entire assembly in any desired location. An upper casting fits on the lower one and can be moved transversely upon it on some type of keyed ways. This transverse motion permits aligning the tailstock and headstock spindles and provides amethod of turning tapers. The third major component of the assembly is the tailstock quill. This is a hollow steel cylinder，usually about2 to3 inches in diameter，that can be moved several inches longitudinally in and out of the upper casting by means of a hand wheel and screw. The open end of the quill hole terminates in a Morse taper in which a lathe center，or various tools such as drills，can be held. A graduated scale，several inches in length，usually is engraved on the outside of the quill to aid in controlling its motion in and out of the upper casting. A locking device permits clamping the quill in any desired position.The carriage assembly provides the means for mounting and moving cutting tools. The carriage is a relatively flat H-shaped casting that rests and moves on the outer set of ways on the bed. The transverse bar of the carriage contains ways on which the cross slide is mounted and can be moved by means of a feed screw that is controlled by a small hand wheel and a graduated dial. Through the cross slide a means is provided for moving the lathe tool in the direction normal to the axis of rotation of the work.On most lathes the tool post actually is mounted on a compound rest. This consists of abase，which is mounted on the cross slide so that it can be pivoted about a vertical axis，and an upper casting. The upper casting is mounted on ways on this base so that it can be moved back and forth and controlled by means of a short lead screw operated by a hand wheel and a calibrated dial.Manual and powered motion for the carriage，and powered motion for the cross slide，is provided by mechanisms within the apron，attached to the front of the carriage. Manual movement of the carriage along the bed is effected by turning a hand wheel on the front of the apron，which is geared to a pinion on the back side. This pinion engages a rack that is attached beneath the upper front edge of the bed in an inverted position.To impart powered movement to the carriage and cross slide，a rotating feed rod is provided. The feed rod，which contains a keyway through out most of its length，passes through the two reversing bevel pinions and is keyed to them . Either pinion cam be brought into mesh with amating bevel gear by means of the reversing lever on the front of the apron and thus provide “forward” or “reverse” power to the carriage. Suitable clutches connect either the rack pinion orthe cross-slide screw to provide longitudinal motion of the carriage or transverse motion of cross slide.For cutting threads，a second means of longitudinal drive is provided by a lead screw. Whereas motion of the carriage when driven by the feed-rod mechanism takes place through a friction clutch in which slippage is possible，motion through the lead screw is by a direct，mechanical connection between the apron and the lead screw. This is achieved by a split nut. By means of a clamping lever on the front of the apron，the split nut can be closed around the lead screw. With the split nut closed，the carriage is moved along the lead screw by direct drive without possibility of slippage.Modern lathes have a quick-change gear box. The input end of this gearbox is driven from the lathe spindle by means of suitable gearing. The out put end of the gear box is connected to the feed rod and lead screw. Thus，through this gear train，leading from the spindle to the quick-change gearbox，thence to the lead screw and feed rod，and then to the carriage，the cutting tool can be made to move a specific distance，either longitudinally or transversely，for each revolution of the spindle. A typical lathe provides，through the feed rod，forty-eight feeds ranging from 0.002 inch to0.118 inch per revolution of the spindle，and，through the lead screw，leads for cutting forty-eight different threads from 1.5 to 92perinch.On some older and some cheaper lathes，one or two gears in the gear train between the spindle and the change gear box must be changed in order to obtain a full range of threads and feeds.Milling is a basic machining process in which the surface is generated by the progressive formation and removal of chips of material from the workpiece as it is fed to a rotating cutter in a direction perpendicular to the axis of the cutter. .In some cases the workpiece is stationary and the cutter is fed to the work. In most instances a multiple-tooth cutter is used so that the metal removal rate is high，and frequently the desired surface is obtained in a single pass of the work.The tool used in milling is known as a milling cutter. It usually consists of acylindrical body which rotates on its axis and contains equally spaced peripheral teeth that intermittently engage and cut the workpiece. In some cases the teeth extend part way across one or both ends of the cylinder.Because the milling principle provides rapid metal removal and can produce good surface finish，it is particularly well-suited for mass-production work，and excellent milling machines have been developed for this purpose. However，very accurate and versatile milling machines of a general-purpose nature also have been developed that are widely used in job-shop and tool and die work. A shop that is equipped with a milling machine and an engine lathe can machine almost any type of product of suitable size.Types of Milling Operations. Milling operations can be classified into two broad categories，each of which has several variations：1.In peripheral milling a surface is generated by teeth located in the periphery of the cutter body；the surface is parallel with the axis of rotation of the cutter. Both flat and formed surfaces can be produced by this method. The cross section of the resulting surface corresponds to the axial contour of the cutter. This procedure often is called slab milling.1.In face milling the generated flat surface is at right angles to the cutteraxis and is thecombined result of the actions of the portions of the teeth located on both the periphery and thewith the face portions providing a finishing action.The basic concepts of peripheral and face milling are illustrated in Fig. Peripheral milling operations usually are performed on machines having horizontal spindles，whereas face milling is done on both horizontal-and vertical-spindle machines.Surface Generation in Milling. Surfaces can be generated in milling by two distinctly different methods depicted in Fig. Note that in up milling the cutter rotates against the direction of feed the workpiece，whereas in down milling the rotation is in the same direction as the feed .As shown in Fig., the method of chip formation is quitedifferent in the two cases. In up milling the c hip is very thin at the beginning, where the tooth first contacts the work，and increases in thickness, be-coming a maximum where the tooth leaves the work. The cutter tends to push the work along and lift it upward from the table. This action tends to eliminate any effect of looseness in the feed screw and nut of the milling machine table and results in a smooth cut. However, the action also tends to loosen the work from the clamping device so that greater clamping forcers must be employed. In addition, the smoothness of the generated surface depends greatly on the sharpness of the cutting edges.In down milling，maximum chip thickness occurs close to the point at which the tooth contacts the work. Because the relative motion tends to pull the workpiece into the cutter，all possibility of looseness in the table feed screw must be eliminated if down milling is to be used. It should never be attempted on machines that are not designed for this type of milling. In as mush as the material yields in approximately a tangential direction at the end of the tooth engagement，there is much less tendency for the machined surface to show tooth marks than when up milling is used. Another consider able advantage of down milling is that the cutting force tends to hold the work against the machine table，permitting lower clamping force to be employed. This is particularly advantageous when milling thin workpiece or when taking heavy cuts.Sometimes a disadvantage of down milling is that the cutter teeth strike against the surface of the work at the beginning of each chip. When the workpiece has a hard surface，such as castings do，this may cause the teeth to dull rapidly.Milling Cutters. Milling cutters can be classified several ways. One method is to group them into two broad classes，based on tooth relief，as follows：1. Profile-cutters have relief provided on each tooth by grinding a small land back of the cutting edge. The cutting edge may be straight or curved.2.In form or cam-relieved cutters the cross section of each tooth is an eccentric curve behind the cutting edge，thus providing relief. All sections of the eccentric relief，parallel with the cutting edge，must have the same contour as the cutting edge. Cutters of this type are sharpened by grinding only the face of the teeth，with the contour of the cutting edge thus remaining unchanged.Another useful method of classification is according to the method of mounting the cutter. Arbor cutters are those that have a center hole so they can be mounted on an arbor. Shank cutters have either tapered or straight integral shank. Those with tapered shanks can be mounted directly in the milling machine spindle，whereas straight-shank cutters are held in a chuck. Facing cuttersusually are bolted to the end of a stub arbor.Types of Milling Cutters. Plain milling cutters are cylindrical or disk-shaped，having straight or helical teeth on the periphery. They are used for milling flat surfaces. This type of operation is called plain or slab milling. Each tooth in a helical cutter engages the work gradually，and usually more than one tooth cuts at a given time. This reduces shock and chattering tendencies and promotes a smoother surface. Consequently，this type of cutter usually is preferred over one with straight teeth. Side milling cutters are similar to plain milling cutters except that the teeth extend radially part way across one or both ends of the cylinder toward the center. The teeth may be either straight or helical. Frequently these cutters are relatively narrow，being disklike in shape. Two or more side milling cutters often are spaced on an arbor to make simultaneous，parallel cuts，in an operation called straddle milling.Interlocking slotting cutters consist of two cutters similar to side mills，but made to operate as a unit for milling slots. The two cutters are adjusted to the desired width by inserting shims between them.Staggered-tooth milling cutters are narrow cylindrical cutters having staggered teeth，and with alternate teeth having opposite helix angles. They are ground to cut only on the periphery，but each tooth also has chip clearance ground on the protruding side. These cutters have a free cutting action that makes them particularly effective in milling deep slots. Metal-slitting saws are thin，plain milling cutters，usually from 1/32 to 3/16 inch thick，which have their sides slightly“dished”to provide clearance and prevent binding. They usually have more teeth per inch of diameter than ordinary plain milling cutters and are used for milling deep，narrow slots and for cutting-off operations.附录2车床和铣床车间里拥有一台车床和一台普通铣床就能加工出具有适合尺寸的各种产品。
高速铣削夹具外文文献翻译、中英文翻译、外文翻译
英文资料High-speed millingHigh-speed machining is an advanced manufacturing technology, different from the traditional processing methods. The spindle speed, cutting feed rate, cutting a small amount of units within the time of removal of material has increased three to six times. With high efficiency, high precision and high quality surface as the basic characteristics of the automobile industry, aerospace, mold manufacturing and instrumentation industry, such as access to a wide range of applications, has made significant economic benefits, is the contemporary importance of advanced manufacturing technology. For a long time, people die on the processing has been using a grinding or milling EDM (EDM) processing, grinding, polishing methods. Although the high hardness of the EDM machine parts, but the lower the productivity of its application is limited. With the development of high-speed processing technology, used to replace high-speed cutting, grinding and polishing process to die processing has become possible. To shorten the processing cycle, processing and reliable quality assurance, lower processing costs.1 One of the advantages of high-speed machiningHigh-speed machining as a die-efficient manufacturing, high-quality, low power consumption in an advanced manufacturing technology. In conventional machining in a series of problems has plagued by high-speed machining of the application have been resolved.1.1 Increase productivityHigh-speed cutting of the spindle speed, feed rate compared withtraditional machining, in the nature of the leap, the metal removal rate increased 30 percent to 40 percent, cutting force reduced by 30 percent, the cutting tool life increased by 70% . Hardened parts can be processed, a fixture in many parts to be completed rough, semi-finishing and fine, and all other processes, the complex can reach parts of the surface quality requirements, thus increasing the processing productivity and competitiveness of products in the market.1.2 Improve processing accuracy and surface qualityHigh-speed machines generally have high rigidity and precision, and other characteristics, processing, cutting the depth of small, fast and feed, cutting force low, the workpiece to reduce heat distortion, and high precision machining, surface roughness small. Milling will be no high-speed processing and milling marks the surface so that the parts greatly enhance the quality of the surface. Processing Aluminum when up Ra0.40.6um, pieces of steel processing at up to Ra0.2 ~ 0.4um.1.3 Cutting reduce the heatBecause the main axis milling machine high-speed rotation, cutting a shallow cutting, and feed very quickly, and the blade length of the workpiece contacts and contact time is very short, a decrease of blades and parts of the heat conduction. High-speed cutting by dry milling or oil cooked up absolute (mist) lubrication system, to avoid the traditional processing tool in contact with the workpiece and a lot of shortcomings to ensure that the tool is not high temperature under the conditions of work, extended tool life.1.4 This is conducive to processing thin-walled partsHigh-speed cutting of small cutting force, a higher degree of stability, Machinable with high-quality employees compared to the company may be very good, but other than the company's employees may Suanbu Le outstanding work performance. For our China practice, we use the models to determine the method of staff training needs are simple and effective. This study models can be an external object, it can also be a combination of internal and external. We must first clear strategy for the development of enterprises. Through the internal and external business environment and organizational resources, such as analysis, the future development of a clear business goals and operational priorities. According to the business development strategy can be compared to find the business models, through a comparative analysis of the finalization of business models. In determining business models, a, is the understanding of its development strategy, or its market share and market growth rate, or the staff of the situation, and so on, according to the companies to determine the actual situation. As enterprises in different period of development, its focus is different, which means that enterprises need to invest the manpower and financial resources the focus is different. So in a certain period of time, enterprises should accurately selected their business models compared with the departments and posts, so more practical significance, because the business models are not always good, but to compare some aspects did not have much practical significance, Furthermore This can more fully concentrate on the business use of limited resources. Identify business models, and then take the enterprise of the corresponding departments and staff with the business models for comparison, the two can be found in the performance gap, a comparative analysis to find reasons, in accordance with this business reality, the final identification of training needs. The cost of training is needed, if not through an effective way to determine whether companies need to train and the training of the way, but blind to training, such training is difficult to achieve the desired results. A comparison only difference between this model is simple and practical training.1.5 Can be part of some alternative technology, such as EDM, grinding high intensity and high hardness processingHigh-speed cutting a major feature of high-speed cutting machine has the hardness of HRC60 parts. With the use of coated carbide cutter mold processing, directly to the installation of ahardened tool steel processing forming, effectively avoid the installation of several parts of the fixture error and improve the parts of the geometric location accuracy. In the mold of traditional processing, heat treatment hardening of the workpiece required EDM, high-speed machining replace the traditional method of cutting the processing, manufacturing process possible to omit die in EDM, simplifying the processing technology and investment costs .High-speed milling in the precincts of CNC machine tools, or for processing centre, also in the installation of high-speed spindle on the general machine tools. The latter not only has the processing capacity of general machine tools, but also for high-speed milling, a decrease of investment in equipment, machine tools increased flexibility. Cutting high-speed processing can improve the efficiency, quality improvement, streamline processes, investment and machine tool investment and maintenance costs rise, but comprehensive, can significantly increase economic efficiency.2 High-speed millingHigh-speed milling the main technical high-speed cutting technology is cutting the development direction of one of it with CNC technology, microelectronic technology, new materials and new technology, such as technology development to a higher level. High-speed machine tools and high-speed tool to achieve high-speed cutting is the prerequisite and basic conditions, in high-speed machining in the performance of high-speed machine tool material of choice and there are strict requirements.2.1 High-speed milling machine in order to achieve high-speed machiningGeneral use of highly flexible high-speed CNC machine tools, machining centers, and some use a dedicated high-speed milling, drilling. At the same time a high-speed machine tool spindle system and high-speed feeding system, high stiffness of the main characteristics of high-precision targeting and high-precision interpolation functions, especially high-precision arc interpolation function. High-speed machining systems of the machine a higher demand, mainly in the following areas:General use of highly flexible high-speed CNC machine tools, machining centers, and some use a dedicated high-speed milling, drilling. At the same time a high-speed machine tool spindle system and high-speed feeding system, high stiffness of the main characteristics of high-precision targeting and high-precision interpolation functions, especially high-precision arc interpolation function. High-speed machining systems of the machine a higher demand, mainly in the following areas:High-speed milling machine must have a high-speed spindle, the spindle speed is generally 10000 ~ 100000 m / min, power greater than 15 kW. But also with rapid speed or in designated spots fast-stopping performance. The main axial space not more than 0 .0 0 0 2 m m. Often using high-speed spindle-hydrostatic bearings, air pressure-bearing, mixed ceramic bearings, magneticbearing structure of the form. Spindle cooling general use within the water or air cooled.High-speed processing machine-driven system should be able to provide 40 ~ 60 m / min of the feed rate, with good acceleration characteristics, can provide 0.4 m/s2 to 10 m/s2 acceleration and deceleration. In order to obtain good processing quality, high-speed cutting machines must have a high enough stiffness. Machine bed material used gray iron, can also add a high-damping base of concrete, to prevent cutting tool chatter affect the quality of processing. A high-speed data transfer rate, can automatically increase slowdown. Processing technology to improve the processing and cutting tool life. At present high-speed machine tool manufacturers, usually in the general machine tools on low speed, the feed of the rough and then proceed to heat treatment, the last in the high-speed machine on the half-finished and finished, in improving the accuracy and efficiency at the same time, as far as possible to reduce processing Cost.2.2 High-speed machining toolHigh-speed machining tool is the most active one of the important factors, it has a direct impact on the efficiency of processing, manufacturing costs and product processing and accuracy. Tool in high-speed processing to bear high temperature, high pressure, friction, shock and vibration, such as loading, its hardness and wear-resistance, strength and toughness, heat resistance, technology and economic performance of the basic high-speed processing performance is the key One of the factors. High-speed cutting tool technology development speed, the more applications such as diamond (PCD), cubic boron nitride (CBN), ceramic knives, carbide coating, (C) titanium nitride Carbide TIC (N) And so on. CBN has high hardness, abrasion resistance and the extremely good thermal conductivity, and iron group elements between the great inertia, in 1300 ℃ would not have happened significant role in the chemical, also has a good stability. The experiments show that with CBN cutting toolHRC35 ~ 67 hardness of hardened steel can achieve very high speed. Ceramics have good wear resistance and thermal chemical stability, its hardness, toughness below the CBN, can be used for processing hardness of HRC <5 0 parts. Carbide Tool good wear resistance, but the hardness than the low-CBN and ceramics. Coating technology used knives, cutting tools can improve hardness and cutting the rate, for cutting HRC40 ~ 50 in hardness between the workpiece. Can be used to heat-resistant alloys, titanium alloys, hightemperature alloy, cast iron, Chungang, aluminum and composite materials of high-speed cutting Cut, the most widely used. Precision machining non-ferrous metals or non-metallic materials, or the choice of polycrystalline diamond Gang-coated tool.2.3 High-speed processing technologyHigh-speed cutting technology for high-speed machining is the key. Cutting Methods misconduct, will increase wear tool to less than high-speed processing purposes. Only high-speed machine tool and not a good guide technology, high-speed machining equipment can not fullyplay its role. In high-speed machining, should be chosen with milling, when the milling cutter involvement with the workpiece chip thickness as the greatest, and then gradually decreased. High-speed machining suitable for shallow depth of cut, cutting depth of not more than 0.2 mm, to avoid the location of deviation tool to ensure that the geometric precision machining parts. Ensure that the workpiece on the cutting constant load, to get good processing quality. Cutting a single high-speed milling path-cutting mode, try not to interrupt the process and cutting tool path, reducing the involvement tool to cut the number to be relatively stable cutting process. Tool to reduce the rapid change to, in other words when the NC machine tools must cease immediately, or Jiangsu, and then implement the next step. As the machine tool acceleration restrictions, easy to cause a waste of time, and exigency stop or radical move would damage the surface accuracy. In the mold of high-speed finishing, in each Cut, cut to the workpiece, the feed should try to change the direction of a curve or arc adapter, avoid a straight line adapter to maintain the smooth process of cutting.3 Die in high-speed milling processing ofMilling as a highly efficient high-speed cutting of the new method,inMould Manufacturing has been widely used. Forging links in the regular production model, with EDM cavity to be 12 ~ 15 h, electrodes produced 2 h. Milling after the switch to high-speed, high-speed milling cutter on the hardness of HRC 6 0 hardened tool steel processing. The forging die processing only 3 h20min, improve work efficiency four to five times the processing surface roughness of Ra0.5 ~ 0.6m, fully in line with quality requirements.High-speed cutting technology is cutting technology one of the major developments, mainly used in automobile industry and die industry, particularly in the processing complex surface, the workpiece itself or knives rigid requirements of the higher processing areas, is a range of advanced processing technology The integration, high efficiency and high quality for the people respected. It not only involves high-speed processing technology, but also including high-speed processing machine tools, numerical control system, high-speed cutting tools and CAD / CAM technology. Die-processing technology has been developed in the mold of the manufacturing sector in general, and in my application and the application of the standards have yet to be improved, because of its traditional processing with unparalleled advantages, the future will continue to be an inevitable development of processing technology Direction.4 Numerical control technology and equipping development trend and countermeasureEquip the engineering level, level of determining the whole national economy of the modernized degree and modernized degree of industry, numerical control technology is it develop new developing new high-tech industry and most advanced industry to equip (such as information technology and his industry, biotechnology and his industry, aviation, spaceflight, etc. national defense industry) last technology and getting more basic most equipment. Marx has ever said "the differences of different economic times, do not lie in what is produced, and lie in how to produce,produce with some means of labor ". Manufacturing technology and equipping the most basic means of production that are that the mankind produced the activity, and numerical control technology is nowadays advanced manufacturing technology and equips the most central technology. Nowadays the manufacturing industry all around the world adopts numerical control technology extensively, in order to improve manufacturing capacity and level, improve the adaptive capacity and competitive power to the changeable market of the trends. In addition every industrially developed country in the world also classifies the technology and numerical control equipment of numerical control as the strategic materials of the country, not merely take the great measure to develop one's own numerical control technology and industry, and implement blockading and restrictive policy to our country in view of " high-grade, precision and advanced key technology of numerical control " and equipping. In a word, develop the advanced manufacturing technology taking numerical control technology as the core and already become every world developed country and accelerate economic development in a more cost-effective manner, important way to improve the overall national strength and national position. Numerical control technology is the technology controlled to mechanical movement and working course with digital information, integrated products of electromechanics that the numerical control equipment is the new technology represented by numerical control technology forms to the manufacture industry of the tradition and infiltration of the new developing manufacturing industry, namely the so-called digitization is equipped, its technological range covers a lot of fields: (1)Mechanical manufacturing technology; (2)Information processing, processing, transmission technology; (3)Automatic control technology; (4)Servo drive technology;(5)Technology of the sensor; (6)Software engineering ,etc..Development trend of a numerical control technologyThe application of numerical control technology has not only brought the revolutionary change to manufacturing industry of the tradition, make the manufacturing industry become the industrialized symbol , and with the constant development of numerical control technology and enlargement of the application, the development of some important trades (IT , automobile , light industry , medical treatment ,etc. ) to the national economy and the people's livelihood of his plays a more and more important role, because the digitization that these trades needed to equip has already been the main trend of modern development. Numerical control technology in the world at present and equipping the development trend to see, there is the following several respect [1- ] in its main research focus.5 A high-speed, high finish machining technology and new trend equippedThe efficiency, quality are subjavanufacturing technology. High-speed, high finish machining technology can raise the efficiency greatly , improve the quality and grade of the products, shorten production cycle and improve the market competitive power. Japan carries the technological research association first to classify it as one of the 5 great modern manufacturing technologies forthis, learn (CIRP) to confirm it as the centre in the 21st century and study one of the directions in international production engineering.In the field of car industry, produce one second when beat such as production of 300,000 / vehicle per year, and many variety process it is car that equip key problem that must be solved one of; In the fields of aviation and aerospace industry, spare parts of its processing are mostly the thin wall and thin muscle, rigidity is very bad, the material is aluminium or aluminium alloy, only in a situation that cut the speed and cut strength very small high, could process these muscles, walls. Adopt large-scale whole aluminium alloy method that blank " pay empty " make the wing recently, such large-scale parts as the fuselage ,etc. come to substitute a lot of parts to assemble through numerous rivet , screw and other connection way, make the intensity , rigidity and dependability of the component improved. All these, to processing and equipping the demand which has proposed high-speed, high precise and high flexibility.According to EMO2001 exhibition situation, high-speed machining center is it give speed can reach 80m/min is even high , air transport competent speed can up to 100m/min to be about to enter. A lot of automobile factories in the world at present, including Shanghai General Motors Corporation of our country, have already adopted and substituted and made the lathe up with the production line part that the high-speed machining center makes up. HyperMach lathe of U.S.A. CINCINNATI Company enters to nearly biggest 60m/min of speed, it is 100m/min to be fast, the acceleration reaches 2g, the rotational speed of the main shaft has already reached 60 000r/min. Processing a thin wall of plane parts, spend 30min only, and same part general at a high speed milling machine process and take 3h, the ordinary milling machine is being processed to need 8h; The speed and acceleration of main shaft of dual main shaft lathes of Germany DMG Company are up to 120000r/mm and 1g.In machining accuracy, the past 10 years, ordinary progression accuse of machining accuracy of lathe bring 5μm up to from 10μm already, accurate grades of machining center from 3～5μm, rise to 1～1.5μm, and ultraprecision machining accuracy is i t enter nanometer grade to begin already (0.01μm).In dependability, MTBF value of the foreign numerical control device has already reached above 6 000h, MTBF value of the servo system reaches above 30000h, demonstrate very high dependability .In order to realize high-speed, high finish machining, if the part of function related to it is electric main shaft, straight line electrical machinery get fast development, the application is expanded further .5.2 Link and process and compound to process the fast development of the lathe in 5 axesAdopt 5 axles to link the processing of the three-dimensional curved surface part, can cut with the best geometry form of the cutter , not only highly polished, but also efficiency improves by a large margin . It is generally acknowledged, the efficiency of an 5 axle gear beds can equal 2 3 axle gearbeds, is it wait for to use the cubic nitrogen boron the milling cutter of ultra hard material is milled and pared at a high speed while quenching the hard steel part, 5 axles link and process 3 constant axles to link and process and give play to higher benefit. Because such reasons as complicated that 5 axles link the numerical control system , host computer structure that but go over, it is several times higher that its price links the numerical control lathe than 3 axles , in addition the technological degree of difficulty of programming is relatively great, have restricted the development of 5 axle gear beds.At present because of electric appearance of main shaft, is it realize 5 axle complex main shaft hair structure processed to link greatly simplify to make, it makes degree of difficulty and reducing by a large margin of the cost, the price disparity of the numerical control system shrinks. So promoted 5 axle gear beds of head of complex main shaft and compound to process the development of the lathe (process the lathe including 5).At EMO2001 exhibition, new Japanese 5 of worker machine process lathe adopt complex main shaft hair, can realize the processing of 4 vertical planes and processing of the wanton angle, make 5 times process and 5 axles are processed and can be realized on the same lathe, can also realize the inclined plane and pour the processing of the hole of awls. Germany DMG Company exhibits the DMUVoution series machining center, but put and insert and put processing and 5 axles 5 times to link and process in once, can be controlled by CNC system or CAD/CAM is controlled directly or indirectly.5.3 Become the main trend of systematic development of contemporary numerical control intelligently, openly, networkedly.The numerical control equipment in the 21st century will be sure the intelligent system, the intelligent content includes all respects in the numerical control system: It is intelligent in order to pursue the efficiency of processing and process quality, control such as the self-adaptation of the processing course, the craft parameter is produced automatically; Join the convenient one in order to improve the performance of urging and use intelligently, if feedforward control , adaptive operation , electrical machinery of parameter , discern load select models , since exactly makes etc. automatically; The ones that simplified programming , simplified operating aspect are intelligent, for instance intelligent automatic programming , intelligent man-machine interface ,etc.; There are content of intelligence diagnose , intelligent monitoring , diagnosis convenient to be systematic and maintaining ,etc..Produce the existing problem for the industrialization of solving the traditional numerical control system sealing and numerical control application software. A lot of countries carry on research to the open numerical control system at present, such as NGC of U.S.A. (The Next Generation Work-Station/Machine Control), OSACA of European Community (Open System Architecture for Control within Automation Systems), OSEC (Open System Environment for Controller) of Japan, ONC (Open Numerical Control System) of China, etc.. The numerical control system melts tobecome the future way of the numerical control system open. The so-called open numerical control system is the development of the numerical control system can be on unified operation platform, face the lathe producer and end user, through changing, increasing or cutting out the structure target(numerical control function), form the serration, and can use users specially conveniently and the technical know-how is integrated in the control system, realize the open numerical control system of different variety , different grade fast, form leading brand products with distinct distinction. System structure norm of the open numerical control system at present, communication norm , disposing norm , operation platform , numerical control systematic function storehouse and numerical control systematic function software development ,etc. are the core of present research.The networked numerical control equipment is a new light spot of the fair of the internationally famous lathe in the past two years. Meeting production line , manufacture system , demand for the information integration of manufacturing company networkedly greatly of numerical control equipment, realize new manufacture mode such as quick make , fictitious enterprise , basic Entrance that the whole world make too. Some domestic and international famous numerical control lathes and systematic manufacturing companies of numerical control have all introduced relevant new concepts and protons of a machine in the past two years, if in EMO2001 exhibition, " Cyber Production Center " that the company exhibits of mountain rugged campstool gram in Japan (Mazak) (intellectual central production control unit, abbreviated as CPC); The lathe company of Japanese big Wei (Okuma ) exhibits " IT plaza " (the information technology square , is abbreviated as IT square ); Open Manufacturing Environment that the company exhibits of German Siemens (Siemens ) (open the manufacturing environment, abbreviated as OME),etc., have reflected numerical control machine tooling to the development trend of networked direction.5.4 Pay attention to the new technical standard, normal setting-up5.4.1 Design the norm of developing about the numerical control systemAs noted previously, there are better common ability, flexibility, adaptability, expanding in the open numerical control system, such countries as U.S.A. ,European Community and Japan ,etc. implement the strategic development plan one after another , carry on the research and formulation of the systematic norm (OMAC , OSACA , OSEC ) of numerical control of the open system structure, 3 biggest economies in the world have carried on the formulation that nearly the same science planned and standardized in a short time, have indicated a new arrival of period of change of numerical control technology. Our country started the research and formulation of standardizing the frame of ONC numerical control system of China too in 2000.5.4.2 About the numerical control standardThe numerical control standard is a kind of trend of information-based development of manufacturing industry. Information exchange among 50 years after numerical control technology was born was all because of ISO6983 standard, namely adopt G, M code describes how processes,。
变速箱换挡叉的加工工艺及夹具设计(中英文文献)
毕业论文附件材料目录1 英文文献翻译 (1)1.1 Shift gearbox (1)1.2 变速箱的换挡方式 (12)1 英文文献翻译1.1 Shift gearboxClassification usually gearbox as follows:Manual transmissionThe general automatic gearbox / mon automatic transmission with tiptronicCVT stepless gearbox with gear box of the /CVTDual clutch gearboxSequential gearbox(1) manual gearboxManual transmission, also known as manual gear, English name is manual transmission, referred to as MT, which push the shift lever to change gears meshing position inside the transmission, changing the transmission ratio, so as to achieve the purpose of speed. Step on the clutch, can move the shift lever.The working principle of a manual gearboxThe manual gear box is posed of different gear ratio of the gear group, its basic principle is through the gear group work in different, to realize the transformation of gear ratio. As the key link for power distribution, transmission must have the power input shaft and the output shaft of the big two, together constitute the transmission gear, is a manual transmission is the most basic ponent. The power input is connected with the clutch shaft clutch transmission, from the power to directly through the input shaft to the group, the gear set is posed of different diameter gear, gear power transmission effectof different proportion reached is pletely different, the usual shift driving also refers to change gear ratio.Next, let us through a simple model to tell you, the principle of manual gearbox shift. Below is a simple structural model of 3 axis 2 speed gearbox.The input shaft (green) is also called the first shaft, connected by a clutch and engine, shaft and the gear is a hard connected ponents. Red is called the intermediate gear shaft. Enter the two gear shaft and intermediate shaft is in constant mesh state, so when the input shaft rotates will drive shaft rotation. Yellow is the output shaft, it is also called the second shafts and connected to the drive shaft (only for rear wheel drive, the precursor is generally two), and then through the differential drive vehicles.When the wheel rotates the same with spline shaft to rotate together, at this time,blue gear shaft can occur on the spline shaft relative free rotation. Therefore, the engine stops, and the wheel is rotated, the blue gear and shaft in the stationary state, and the spline shaft with wheels. The principle and the rear axle of the bicycle flywheel is similar. Blue gear and spline shaft is posed of a sleeve to connect, sleeve with spline shaft to rotate, but also can be free to slide on the spline shaft to gear.With these, the shifting process is very good understanding, when connecting sleeve and a blue gear, engine power will be transmitted to the output shaft through the shaft, at the same time, blue gear left in free rotation, but because there is no and sleeve engaged, so it does not affect the spline shaft. If the sleeve between the two blue gear, the gearbox in neutral position, the two blue gear on the spline shaft rotate freely, without mutual interference.Principle of a conventional 5 speed manual gearbox shift is the same, only thegearbox structure increased the number of sleeve and the gear sets, so that it has more gear. But the reverse is based on the intermediate shaft (red) and the output shaft (blue) is added between a gear to achieve. Due to the increase of a gear, the reverse gear will always rotate toward other gear in the opposite direction. The gear because only to change gear rotation direction function, so it is also called the idler.5 block two shaft transmission structure, the input shaft and the driving gear are integrated into a whole, simplifies the structure and saves spaceIn addition to the traditional three axis manual gearbox, the widespread use of cars is two axis manual transmission, its structure and the three shaft of the gearbox is similar, only the input shaft and intermediate shaft as a shaft, therefore has the advantages of simple structure, small size advantages, in addition, it also has the middle gear transmission high efficiency, and low noise characteristics, so it is more suitable to be theprecursor home car general car transmission form, is currently the most widely used, its shortings is not set up direct gear, transmission and file than the design cannot be too high. While driving, three shaft gearbox used is still the traditional.Manual gearbox in general, is through the push rod is connected or cable to control the shift. Push rod shift control connection, more direct but vibration will be large; and the cable type although no vibration, but the shift is not very clear, it is each to have good and bad. In addition to shift the two pure mechanical control, in addition, and the use of electronic shift device of manual transmission, which can bine the merits of push and pull the shift between the good. This kind of gear box in the shift when the gear shift lever, shifting to the corresponding gear, the transmission will be motor drive the corresponding fork control sleeve and the gear is engaged, so that there is no gear is not clear, but the shift schedule can be controlled in the ideal range.So, a good manual transmission need to have what characteristic? The first transmission must have good gear handle, each gear position clear, have reasonable horizontal and vertical stroke, into the block resistance is small and with suction. What is more important is, the gear tooth between than arrangement must be reasonable. Because each gear position than distribution, directly affect the cohesion power vehicles moving in a smooth, usually require a low gear can effectively accelerate, high block to achieve high speed and efficient, and the distance between each block should be uniform, otherwise will be very easy to cause the channeling shift when the car.Analysis of the advantages and disadvantages of manual gearboxAdvantages Obviously, which is simple in structure, reliable performance,manufacturing and maintenance cost is low, and the transmission efficiency is high (theory will be more fuel-efficient), also, because it is pure mechanical control, shift reaction is fast, and can be more direct expression of driver's intention, and therefore more driving pleasure, these are the advantages of manual gearbox. But pared to automatic transmission, its operation is plicated, and frustration in gear switch when the obvious disadvantage is irreparable.(2) automatic gearboxAutomatic transmission AT, the full name of Auto Transmission, which is posed of hydraulic torque converter, posed of planetary gear and hydraulic control system, through the hydraulic transmission and gear bination to achieve variable speed moment.pared with the manual transmission, automatic transmission is very different in structure and usage. The manual is mainly regulated by different gear bination to change gear, and the automatic transmission is through the hydraulic transmission and gear bination to achieve the purpose of changing speed. Hydraulic torque converter is one of the most characteristic of the automatic gearbox parts, which is posed of a pump, turbine and guide wheel and other ponents, pump wheel and turbine is a bination of work, through the liquid pump wheel drives the turbine to rotate, and the wheel between the pump and turbine wheel through the reaction between the pump wheel and turbine implementation the speed difference and implementation of variable torque function, the driver, you only need to different intensity slam the pedal, the gearbox can automatically stop lifting. Since the torque converter automatic transmission torque range is not big enough, so in a later series several rows of planetary gear to improve efficiency, thehydraulic control system will change with the engine to manipulate the planetary gear, so as to realize the automatic transmission torque. In order to meet a variety of running process needs (such as parking, reversing), automatic transmission also has some manual shift lever position, like the P block (R block (anchor), after the block), block N (neutral), D (forward), block.From the performance that the more gear automatic gearbox, the car in the process of running more smoothly, acceleration is better, and more fuel-efficient. In addition to providing a fortable driving feeling, automatic transmission also has insurmountable defects. Dynamic automatic transmission response is not directly, which makes it in the "driving pleasure" slightly shortage. In addition, because of the use of hydraulic transmission, the automatic transmission gearbox transmission power loss.Tiptronic automatic transmissionHands appeared gearbox is in order to improve the automatic gearbox and operating economy and increase the setting, let the original puter automatic shift time back into the hands of drivers. At the same time, if in the city traffic in, or you can always switch back to automatic.A tiptronic automatic transmission is actually automatic gearbox, first appeared in a Porsche 911, manual gearbox electronic control system through the simulation of the operation of a manual gearbox. It appears, giving the driver a greater degree of freedom in the operation, can block up the blocking or shift paddles on the steering wheel to choose their own gear and shift the timing right, thereby greatly improving the driving pleasure.(3) CTV non-polar transmissionCVT (Continuously Variable Transmission), direct translation is a continuously variable transmission, which is continuously variable transmission. We often say, just as its name implies is that there is no clear and specific file, which operate on similar automatic gearbox, gear jump process but the ratio change is different from the automatic gearbox, but a continuous, so the power transmission continues smooth.CVT transmission system, the traditional gear by a pair of pulleys and a steel belt is replaced, each block is V structure is posed of two intervertebral disk, engine shaft is connected through a small pulley, steel belt drive pulley. Mystery lies in this special pulley: drive pulley structures CVT strange activity, divided into halves, can be close to or separate relative. Cone disc can tighten or open the thrust hydraulic, extrusion sheet steel chain so as to adjust the V slot width. When the cone disc inside mobile tightened, steel chain in the extrusion cones to center outside of the direction of movement (centrifugal direction), but moving to the center of the circle. In this way, steel chain drives the disc diameter increases, the transmission ratio is changed.The CVT gearbox what are the advantages?1, because there is no general automatic transmission gear, there will be no shift process of automatic transmission, shift the resulting sense of frustration will disappear, so the power output of CVT gearbox is linear, in actual driving very smooth.Theory of transmission system of 2 CVT, the gear can be an unlimited number of gear set, more freedom, the traditional transmission gear ratio, speed ratio and performance, fuel consumption, exhaust emissions balance, are more likely to achieve.3, the mechanical efficiency of CVT transmission, the province is oily considerably better than the automatic transmission mon, after manual gearbox, fuel economy is much better than.Since there are so many advantages, why not let all the cars using CVT gearbox? There are two factors:1, pared with the traditional automatic transmission, its cost is high; and the operation is undeserved word, the higher probability.2, CVT gearbox itself still has its shortings, is the transmission of the steel belt can withstand strength is limited, generally more than 2.8L capacity or power above 280N • M is its limit, but we also see that there are more and more cars such as Audi, or Nissan, has broken the limit, believe strip the problem will be solved gradually.(4) dual clutch gearboxDual clutch gearbox DCT, English name is Dual Clutch Transmission, because it has two clutches, so called "dual clutch transmission".Technology introducedDual clutch gearbox bines the advantages of manual transmission and automatic transmission, no torque converter, instead of using two sets of clutch, through two sets of clutch alternately work, to achieve seamless shift effect. Two clutches respectively control the odd block and even block, that is to say, in the shift before, DSG had the next gear meshing, after shifting instruction, DSG quickly sends instructions to the engine, the engine speed increases, the previous meshing gears quickly, while the first group of clutch fully liberalized, the pletion of a rise to block the action time, action andso on.Because without the torque converter, so the power of the engine can be fully played out, while the two clutch alternately work, shift time making, dynamic fault engine may be very limited. As the driver is the feeling that we are the most direct, switch gear action very quickly and smoothly, dynamic transmission process of almost uninterrupted, vehicle dynamic performance can be fully play. pared with the traditional automatic transmission with torque converter, the DSG shift more directly, the power loss is smaller, so the fuel consumption can be reduced by more than 10%.DeficienciesHowever, with the traditional automatic transmission ratio, DSG also has some inherent disadvantages, firstly it is because there is no use hydraulic torque converter, nor realize manual transmission "linkage" action, so for the small-displacement engine, low speed torque characteristic is not enough to be pletely exposed; secondly, because the DSG transmission using puter control, belonging to an intelligent transmission, it needs to send electronic signals to the engine block in the process of falling in the L /, the engine after reply, and the engine to be pleted with L / reduction gear. A large number of electronic ponents, but also increases the probability of its failure.The dual clutch mon with Volkswagen's DSG, Ford Powershift, Mitsubishi SST and Porsche PDK.(5) sequential gearboxSequential gearbox (AMT) is improved on the traditional manual gear transmission based on; it bines hydromechatronics automatic transmission has the advantages of bothAT and MT; AMT has the advantages of automatic transmission mon automatic transmission, and the retention efficiency of the original manual transmission gear transmission, the high cost of low, simple structure, easy manufacture. It is the reform in the present manual transmission, retained most of the original assembly, only to change the shift lever manual operating system part, the production of succession, to transform the input costs less, is very easy to be manufacturers to accept.The driver through the accelerator pedal and joystick to the electronic control unit (ECU) control signal transmission; electronic control unit collects the engine speed sensor, the speed sensor signal, the time to master the running state of the vehicle; electronic control unit (ECU) based on the best program according to these signals stored therein, optimal shifting rules, clutch fuzzy control rules engine oil, adaptive control law, action and temporal separation of the engine, clutch and transmission shift binding, the three to achieve the best matching. In order to obtain the excellent fuel economy and power performance and ability to smooth start and rapid shift, in order to achieve the desired results.But the AMT transmission is not perfect, the biggest disadvantage of AMT gearbox is shifting fort is poor, and generate power interruption in the process of shifting, the shift in the process of speed performance is not good.AMT mechanical gearbox, its basic structure and conventional manual gearbox consistent, generally only one input shaft and an output shaft (RWD usually a middle shaft), which generally is the input shaft 5 forward gear and output shaft gear is in constant mesh state, wherein the output shaft of the 1 gear and a reverse gear, 2 blockand the 3 block, 4 block and 5 block were shared by the three shift fork. The mechanism of two adjacent gear with a shifting mechanism, when the shift action, fork need once upon a gear defect, through neutral to the next gear gear meshing, due to three actions is the order, even if each action will be the time to a minimum, is still very difficult to obtain the shift speed fast enough."Independent innovation shift fork"The ISR gearbox has a unique structure, the gear arrangement it is different with the traditional AMT gearbox, also different from the dual clutch gearbox. The use of four independent shift fork, two stalls adjacent to the gear shift fork is posed of different control. Four independent fork respectively control 1 gear and reverse gear; block 3 and block 5, block 2 and block 4, block 6 and block 7, that is to say, from 1 until 6 block, two adjacent stalls are posed of two independent fork to respectively control.Because of this design, the shifting process can be further shortened: when two adjacent gear to gear switch, a shift fork and the current gear gear detachment, another gear meshing has already started, and a shift fork action and activates the electronic clutch three, because the action is almost synchronously, so that the whole time shorten. Lamborghini is pared originally claimed, performance is very good before the generation of the E-gear sequential gearbox, shift speed upgrade 40%, shift speed of 50 milliseconds is close to F1 gearbox level.Gear shift mechanism of ISR is driven by the electric hydraulic pump, a maximum of 60 bar pressure ensures the necessary operating speed, 7 hydraulic valve controls the gear shift mechanism of action, and the electric pump to provide power, double plateclutch tough also driven by hydraulic pressure, will be responsible for the torque of the 690Nm transmitted to the four wheels. Synchronizer gear ring is made from carbon fiber, not only wear but also reduce the overall quality of the gearbox.In the design process, the transmission is not only fast, shift quality is equally important, VOCIS design control procedure is also fully take into account the daily driving fort. The gearbox can choose three kinds of work modes: Strada (Road) or full automatic mode can provide fortable for shift operation oriented; Sport (motion) mode will postpone shifting node and provides a more rapid gear switch; Corsa (track) model can provide the best track shift strategy, the model can also provide the starting control, also is the ejection start function.1.2 变速箱的换挡方式通常变速箱的分类为以下几种：手动变速箱普通自动变速箱/普通自动变速箱带手自一体CVT无级变速箱/CVT带挡位的变速箱双离合变速箱序列变速箱(1) 手动变速箱手动变速器，也称手动挡，英文全称为manual transmission，简称MT，即用手拨动变速杆才能改变变速器内的齿轮啮合位置，改变传动比，从而到达变速的目的。
夹具设计中英文对照
Optimization of fixture design with consideration of thermal deformation inface milling考虑端铣中热变形的最佳化夹具设计Huang, YingAbstract摘要Effective methods of fixture design are proposed to reduce machining error caused by cutting heat in face milling. Experiments show that thermal effect is critical to final error in the finish cut and that it dominates cutting accuracy. Therefore, a mathematical model is structured of the cutting heat source on behalf of the cutting tool, and the flatness error generation process in face finishing is demonstrated by computational simulation based on the moving cutting heat source model with FEW Concerning surface flatness due to the moving cutting heat source for relatively thin plate-shaped workpieces, different methodologies have been proposed to reduce flatness error, namely, the application of additional supports and optimization of the fixturing support layout. Cutting experiments and computational analyses show the effectiveness of the additional supports and the optimization methodology applied on the fixture design in view of flatness error due to cutting heat. The proposed methodologies are applicable and beneficial to improve cutting accuracy not only of plate-shaped workpieces but also of other geometry workpieces.用于减小端铣中因切削热而引起的加工误差的有效的夹具设计方法已经被提出。