附录1机械英语文章翻译
机械工程英语第二版（叶邦彦陈统坚著）机械工程出版社课文翻译
Unit 1 材料的种类（1）材料的分类方法很多。
科学家常用的典型的方法是根据它们的状态分类：固体，液态或气态。
材料也分为有机（可再生）和无机材料（不可再生）。
（2）工业上，材料划分为工程材料或非工程材料。
工程材料用于制造和加工成零件的材料。
非工程材料是化学药品，燃料，润滑剂和其它用于制造又不用来加工成零件的材料。
（3）工程材料可进一步细分为：金属，陶瓷，复合材料，聚合材料，等。
Metals and Metal Alloys 金属和金属合金金属和金属合（4）金属有好的导电好导热性，很多金属有高的强度，高硬度和高的延展性。
象铁，钴，镍这些金属有磁性。
在非常低的温度下，一些金属和金属互化物变成超导体。
（5）合金和纯金属有什么区别？纯金属在元素周期表的特殊区域。
例如用于制造电线的铜和做锅和饮料罐的铝。
合金含有两种以上的金属元素。
改变金属元素的比例可以改变合金的性质。
例如，合金金属的不锈钢，是由铁，镍，和铬组成。
而黄金珠宝含有金镍合金。
（6）为什么要使用金属和合金？很多金属和合金有很高密度并用在要求质量与体积比高的的场合。
一些金属合金，象铝基合金，密度低，用在航空领域可以节省燃料。
很多合金有断裂韧度，可以承受冲击，且耐用。
金属有哪些重要属性？（7）【密度】质量除以体积叫做密度。
很多金属有相对高的密度,特别的，象聚合体。
高密度的材料常是原子量很大，象金或铅。
然而一些金属，像铝或镁密度低，就常常用在要求有金属特性而又要求低质量的场合。
（8）【断裂韧性】断裂韧度用来描述金属抗断裂的能力，特别的，当有裂纹时。
金属通常都有无关紧要的刻痕和凹坑，且有耐冲击性。
足球队员关注这一点当他确信面罩不会被击碎的时候。
（9）【塑形变形】塑性变形表述的是材料在断裂之前弯曲变形的能力。
作为工程师，我们通常设计材料使得能够在正常情况下不变形。
你不会想要一阵强烈的西风就把你的车刮得往东倾斜。
然而，有时，我们可以利用塑性变形。
汽车的承受极限就是在彻底破坏之前靠塑形变形来吸收能量。
机械外文翻译中英文
附录附录1英文原文Rolling Contact BearingsThe concern of a machine designer with ball and roller bearings is fivefold as follows:(a) life in relation to load; (b) stiffness,ie.deflections under load; (c) friction; (d) wear; (e) noise. For moderate loads and speeds the correct selection of a standard bearing on the basis of a load rating will become important where loads are high,although this is usually of less magnitude than that of the shafts or other components associated with the bearing. Where speeds are high special cooling arrangements become necessary which may increase fricitional drag. Wear is primarily associated with the introduction of contaminants,and sealing arrangements must be chosen with regard to the hostility of the environment.Because the high quality and low price of ball and roller bearing depends on quantity production,the task of the machine designer becomes one of selection rather than design. Rolling-contact bearings are generally made with steel which is through-hardened to about 900HV,although in many mechanisms special races are not provided and the interacting surfaces are hardened to about 600HV. It is not surprising that,owing to the high stresses involved,a predominant form of failure should be metal fatigue, and a good deal of work is based on accept values of life and it is general practice in bearing industry to define the load capacity of the bearing as that value below which 90 percent of a batch will exceed life of one million revolutions.Notwithstanding the fact that responsibility for basic design of ball and roller bearings rests with the bearing manufacturer, the machine designer must form a correct appreciation of the duty to be performed by the bearing and be concerned not only with bearing selection but with the conditions for correct installation.The fit of the bearing races onto the shaft or onto the housings is of critical importance because of their combined effect on the internal clearance of the bearing as well as preserving the desired degree of interference fit. Inadequate interference can induce serious trouble from fretting corrosion. The inner race is frequently located axially by against a shoulder. A radius at this point is essential for the avoidance of stress concentration and ball races are provided with a radius or chamfer to follow space for this.Where life is not the determining factor in design, it is usual to determine maximum loadingby the amount to which a bearing will deflect under load. Thus the concept of "static load-carrying capacity" is understood to mean the load that can be applied to a bearing, which is either stationary or subject to slight swiveling motions, without impairing its running qualities for subsequent rotational motion. This has been determined by practical experience as the load which when applied to a bearing results in a total deformation of 0.0025mm for a ball 25mm in diameter.The successful functioning of many bearings depends upon providing them with adequate protection against their environment, and in some circumstances the environment must be protected from lubricants or products of deterioration of the bearing design. Moreover, seals which are applied to moving parts for any purpose are of interest to tribologists because they are components of bearing systems and can only be designed satisfactorily on basis of the appropriate bearing theory.Notwithstanding their importance, the amount of research effort that has been devoted to the understanding of the behavior of seals has been small when compared with that devoted to other aspects of bearing technology.LathesLathes are widely used in industry to produce all kinds of machined parts. Some are general purpose machines, and others are used to perform highly specialized operations.Engine lathesEngine lathes, of course, are general-purpose machine used in production and maintenance shop all over the the world. Sized ranger from small bench models to huge heavy duty pieces of equipment. Many of the larger lathes come equipped with attachments not commonly found in the ordinary shop, such as automatic shop for the carriage.Tracer or Duplicating LathesThe tracer or duplicating lathe is designed o produce irregularly shaped parts automatically. The basic operation of this lathe is as fallows. A template of either a flat or three-dimensional shape is placed in a holder. A guide or pointer then moves along this shape and its movement controls that of the cutting tool. The duplication may include a square or tapered shoulder, grooves, tapers, and contours. Work such as motor shafts, spindles, pistons, rods, car axles, turbine shafts, and a variety of other objects can be turned using this type of lathe.Turret LathesWhen machining a complex workpiece on a general-purpose lathe, a great deal of time isspent changing and adjusting the several tools that are needed to complete the work. One of the first adaptations of the engine lathe which made it suitable to mass production was the addition of multi-tool in place of the tailstock. Although most turrets have six stations, some have as many as eight.High-production turret lathes are very complicated machines with a wide variety of power accessories. The principal feature of all turret lathes, however, is that the tools can perform a consecutive serials of operations in proper sequence. Once the tools have been set and adjusted, little skill is require to run out duplicate parts.Automatic Screw MachineScrew machines are similar in construction to turret lathes, except that their heads are designed to hold and feed long bars of stock. Otherwise, their is little different between them. Both are designed for multiple tooling, and both have adaptations for identical work. Originally, the turret lathe was designed as a chucking lathe for machining small casting, forgings, and irregularly shaped workpieces.The first screw machines were designed to feed bar stock and wire used in making small screw parts. Today, however, the turret lathe is frequently used with a collect attachment, and the automatic screw machine can be equipped with a chuck to hold castings.The single-spindle automatic screw machine, as its name implies, machines work on only one bar of stock at a time. A bar 16 to 20 feet long is feed through the headstock spindle and is held firmly by a collect. The machining operations are done by cutting tools mounted on the cross slide. When the machine is in operation, the spindle and the stock are rotated at selected speeds for different operations. If required, rapid reversal of spindle direction is also possible.In the single-spindle automatic screw machine, a specific length of stock is automatically fed through the spindle to a machining area. At this point, the turret and cross slide move into position and automatically perform whatever operations are required. After the machined piece is cut off, stock is again fed into the machining area and the entire cycle is repeated.Multiple-spindle automatic screw machines have from four to eight spindles located around a spindle carrier. Long bars of stock, supported at the rear of the machine,pass though these hollow spindles and are gripped by collects. With the single spindle machines, the turret indexes around the spindle. When one tool on the turret is working, the others are not. With a multiple spindle machine, however, the spindle itself index. Thus the bars of stock are carried to the various end working and side working tools. Each tool operates in only one position, but tollsoperate simultaneously. Therefore, four to eight workpieces can be machined at the same time.Vertical Turret LathesA vertical turret is basically a turret lathe that has been stood on its headstock end. It is designed to perform a variety of turning operations. It consists of a turret, a revolving table, and a side head with a square turret for holding additional tools. Operations performed by any of the tools mounted on the turret or side head can be controlled through the use of stops.Machining CentersMany of today's more sophisticated lathes are called machining centers since they are capable of performing, in addition to the normal turning operations, certain milling and drilling operations. Basically, a machining center can be thought of as being a combination turret lathe and milling machine. Additional features are sometimes included by the versatility of their machines.Numerical ControlOne of the most fundamental concepts in the area of advanced manufacturing technologies is numerical control(NC). Prior to the advent of NC, all machine tools were manually operated and controlled. Among the many limitations associated with manual control machine tools, perhaps none is more prominent than limitation of operator skills. With manual control, the quality of the product is directly related to and limited to the skills of the operator. Numerical control represents the first major step away from human control of machine tools.Numerical control means the control of machine tools and other manufacturing systems through the use of prerecorded, written symbolic instructions. Rather than operating a machine tool, an NC technician tool to be numerically controlled, it must be interfaced with a device for accepting and decoding the programmed instructions, known as a reader.Numerical control was developed to overcome the limitation of human operators, and it has done so. Numerical control machines are more accurate than manually operated machines, they can produce parts more uniformly, they are faster, and the long-run tooling costs are lower. The development of NC led to the development of several other innovations in manufacturing technology:1.Electrical discharge machining.ser cutting.3. Electron beam welding.Numerical control has also made machines tools more versatile than their manually operated predecessors. An NC machine tool can automatically produce a wide variety of parts, each involving an assortment of widely varied and complex machining processes. Numerical control has allowed manufacturers to undertake the production of products that would not have been feasible from an economic perspective using manually controlled machine tools and processes.Like so many advanced technologies, NC was born in the laboratories of the Masschusetts Institute of Technology. The concept of NC was developed in early 1950s with funding provided by the U.S.Air force. In its earliest stages, NC machines were able to make straight cuts efficiently and effectively.However,curved paths were a problem because the machine tool had to be programmed to undertake a series of horizontal and vertical steps to produce a curve. The shorter is straight lines making up the steps, the smoother is the curve. Each line segment in the steps had to be calculated.This problem led to the development in 1959 of the Automatically Programmed Tools(APT) language. This is a special programming language for NC that uses statements similar to English language to define the part geometry, describe the cutting tool configuration, and specify the necessary motions. The development of the APT language was a major step forward in the further development of NC technology. The original NC systems were vastly different from those used today. The machines had hardwired logic circuits. This instructional programs were written on punched paper, which was later to be replaced by magnetic plastic tape. A tape reader was used to interpret the instructions written on the tape for the machine. Together, all of this represented a giant step forward in the control of machine tools. However, there were a number of problems with NC at this point in its development.A major problem wad the fragility of the punched paper tape medium. It was common for the paper tape containing the programmed instructions to break or tear during a machining process. This problem was exacerbated by the fact that each programmed instructions had to be return through the reader. If it was necessary to produce 100 copies of a given part,it was also necessary to run the paper tape through the reader 100 separate times. Fragile paper tapes simply could not withstand the rigors of a shop floor environment and this kind of repeated use.This led to the development of a special magnetic plastic tape. Whereas the paper tape carried the programmed instructions as a series of holes punched in the tape, the plastic tape carried the instructions as a series of magnetic dots. The plastic tape was much stronger than thepaper taps, which solved the problem of frequent tearing and breakage. However, it still left two other problems.The most important of these was that it was difficult or impossible to change the instructions entered on the tape. To make even the most minor adjustments in a program of instructions, it necessary to interrupt machining operations and make a new tape. It was also still necessary to run the tape through the reader as many times as there were parts to be produced. Fortunately, computer technology became a reality and soon solved the problem of NC associated with punched paper and plastic tape.The development of a concept known as direct numerical control(DNC)solved the paper and plastic tape problems associated with numerical control by simply eliminating tape as the medium for carrying the programmed instructions. In direct numerical control machine tools are tied, via a data transmission link, to a host computer. Programs for operating the machine tools are stored in the host computer and fed to the machine tool as needed via the data transmission linkage. Direct numerical control represented a major step forward over punched tape and plastic tape. However, it is subject to the same limitations as all technologies that depend o a host computer. When the lost computer goes down, the machine tools also experience downtime. This problem led to the development of computer numerical control.The development of the microprocessor allowed for the development of programmable logic controllers(PNC)and microcomputer. These two technologies allowed for the development of computer numerical control(CNC). With CNC, each machine tool has a PLC or a microcomputer that serves the same purpose. This allows programs to be input and stored at each individual machine tool. It also allows programs to be developed off-line and download at the individual machine tool. CNC solved the problems associated with downtime of the host computer, but it introduced another known as data management. The same program might be loaded on ten different being solved by local area networks that connect microcomputer for better data management.CNC machine tool feed motion systems CNC machine tool feed motion systems, especially to the outline of the control of movement into the system, must be addressed to the movement into the position and velocity at the same time the realization of two aspects of automatic control, as compared with the general machine tools, require more feed system high positioning accuracy and good dynamic response.A typical closed-loop control of CNC machine tool feed system, usually by comparing the location of amplification unit, drive unit, mechanical transmission components, such as feedbackand testing of several parts. Here as mechanical gear-driven source refers to the movement of the rotary table into a linear motion of the entire mechanical transmission chain, including the deceleration device, turning the lead screw nut become mobile and vice-oriented components and so on. To ensure that the CNC machine tool feed drive system, precision, sensitivity and stability, the design of the mechanical parts of the general requirement is to eliminate the gap, reducing friction, reducing the movement of inertia to improve the transmission accuracy and stiffness. In addition, the feeding system load changes in the larger, demanding response characteristics, so for the stiffness, inertia matching the requirements are very high.Linear Roller GuidesIn order to meet these requirements, the use of CNC machine tools in general low-friction transmission vice, such as anti-friction sliding rail, rail rolling and hydrostatic guideways, ball screws, etc.; transmission components to ensure accuracy, the use of pre-rational, the form of a reasonable support to enhance the stiffness of transmission; deceleration than the best choice to improve the resolution of machine tools and systems converted to the driveshaft on the reduction of inertia; as far as possible the elimination of drive space and reduce dead-zone inverse error and improve displacement precision.Linear Roller Guides outstanding advantage is seamless, and can impose pre-compression. By the rail body, the slider, ball, cage, end caps and so on. Also known as linear rolling guide unit. Use a fixed guide body without moving parts, the slider fixed on the moving parts. When the slider moves along the rail body, ball and slider in the guide of the arc between the straight and through the rolling bed cover of Rolling Road, from the work load to non-work load, and then rolling back work load, constant circulation, so as to guide and move the slider between the rolling into a ball.附录2中文翻译滚动轴承对于球轴承和滚子轴承，一个机械设计人员应该考虑下面五个方面：（a)寿命与载荷关系；（b）刚度，也就是在载荷作用下的变形；（c）摩擦；（d）磨损；（e）噪声。
(完整版)机械电子专业英语翻译
Quality Control Fundamentals质量控制基本原理Quality质量Quality has become one of the most important consumer decision factors in the selection among competing products and services. The phenomenon is widespread, regardless of whether the consumer is an individual, an industrial organization, a retail store, a bank or financial institution, or a military defense program. Consequently, understanding and improving quality are key factors leading to business success, growth, and enhanced competitiveness. There is a substantial return on investment from improved quality and from successfully employing quality as an integral part of overall business strategy.质量是消费者在激烈的产品和服务竞争中进行选择的一个重要因素.不管这个消费者是个人、产业组织、零售店或防务工程,这个想象是普遍存在的.因此,关注并提升质量是取得成功、发展并强化竞争力的关键因素.投资质量的提升并把质量作为经营策略的主要部分将会得到极大地回报.We may define quality in many ways. Most people have a conceptual understanding of quality as relating to one or more desirable characteristics that a product or service should possess. Although this conceptual understanding is certainly a useful starting point, we will give a more precise and useful definition.我们对质量有很多种定义.许多人在观念上把质量理解为产品或服务拥有一个或更多满意的性能.尽管这种概念性理解是有效地,我们将给出更精确、有效地定义.Quality---- characteristic or property consisting of several well-defined technical and aesthetic, hence subjective, considerations; conformance to design (customer) requirement.质量-特性或性能中包含几种明确定义的技术的美学的,因此主观考虑；满足设计（顾客）需求.Quality control------detecting poor quality (nonconformance) in manufactured products and taking corrective action to eliminate i t.质量控制-检测在工业产品中检测不合格的质量（不合格品）并采取纠正措施去避免.The traditional definition of quality is based on the viewpoint that products and services must meet the requirement of those who use them. Therefore, Quality means fitness for use.传统的质量定义是产品或服务必须满足使用者的需求.因此,质量就是适用度There are two general aspects of fitness for use: quality of design and quality of conformance.适用度一般有两个方面:设计质量和一致性的质量。
机械设计专业术语的英语翻译1
机械设计专业术语的英语翻译1机械设计专业术语的英语翻译1 柔性自动化flexibleautomation 润滑油膜lubricantfilm润滑装置lubricationdevice润滑lubrication润滑剂lubricant三角形花键serrationspline三角形螺纹vthreadscrew三维凸轮three - dimensionalcamto stheorem 三心定理kennedy砂轮越程槽grindingwheelgroove砂漏hour glass少齿差行星传动planetarydrivewithsmallteethdifference设计方法学designmethodology设计变量designvariable设计约束designconstraints深沟球轴承deepgrooveballbearing生产阻力productiveresistance升程rise升距lift实际廓线camprofile十字滑块联轴器doubleslidercoupling oldham'scoupling矢量vector输出功outputwork输出构件outputlink输出机构outputmechanism输出力矩outputtorque输出轴outputshaft输入构件inputlink数学模型mathematicmodel实际啮合线actuallineofaction双滑块机构double - slidermechanism, ellipsograph双曲柄机构doublecrankmechanism双曲面齿轮hyperboloidgear双头螺柱studs双万向联轴节constant - velocityordoubleuniversaljoint 双摇杆机构doublerockermechanism双转块机构oldhamcoupling双列轴承doublerowbearing双向推力轴承double - directionthrustbearing松边slack side顺时针clockwise瞬心instantaneouscenter死点deadpoint四杆机构four - barlinkage速度velocity速度不均匀波动系数coefficientofspeedfluctuation速度波动speedfluctuation速度曲线velocitydiagram速度瞬心instantaneouscenterofvelocity塔轮steppulley踏板pedal台钳、虎钳vice太阳轮sungear弹性滑动elasticityslidingmotion弹性联轴器elasticcoupling flexiblecoupling弹性套柱销联轴器rubber - cushionedsleevebearingcoupling 套筒sleeve梯形螺纹acmethreadform特殊运动链specialkinematicchain特性characteristics替代机构equivalentmechanism调节modulation, regulation调心滚子轴承self - aligningrollerbearing调心球轴承self - aligningballbearing调心轴承self - aligningbearing调速speedgoverning调速电动机adjustablespeedmotors调速系统speedcontrolsystem调压调速variablevoltagecontrolGovernor regulator, governorFerromagnetic fluid seals ferrofluidseal Parking phase, stoppingphaseStopping dwellSynchronous belt Synchronousbelt Synchronous belt drive synchronousbeltdrive Convex body convexCam camCam reverse mechanism inversecammechanism Cam mechanism cam, CamMechanismCam profile camprofileCam profile drawing layoutofcamprofile Theoretical profile of cam pitchcurve Flange coupling flangecouplingAtlas and Atlas AtlasGraphical method graphicalmethodPushing distance riseThrust ball bearing thrustballbearing Thrust bearing thrustbearingCutter toolwithdrawalgrooveAnnealed annealGyroscope gyroscopeV band VbeltExternal force externalforceOuter ring outerringOutline size boundarydimensionUniversal coupling Hookscoupling universalcoupling External gear externalgearBending stress beadingstressBending moment bendingmomentWrist wristReciprocating reciprocatingmotionReciprocating seal reciprocatingsealDesign on-netdesign online, ONDInching screw mechanism differentialscrewmechanism Displacement displacementDisplacement curve displacementdiagramPose pose, positionandorientationStable operation stage, steadymotionperiodRobust design robustdesignWorm wormWorm drive mechanism WormgearingNumber of worm heads numberofthreadsDiameter coefficient of worm diametralquotient Worm and worm gear wormandwormgearWorm cam stepping mechanism wormcamintervalmechanism Worm rotation handsofwormWorm gear wormgearPower spring powerspringStepless speed change device steplessspeedchangesdevices Infinity infiniteTie crankarm, planetcarrierField balancing fieldbalancingRadial bearing radialbearingCentripetal force centrifugalforceRelative velocity relativevelocityRelative motion relativemotionRelative clearance relativegapQuadrant quadrantClay plasticineFine tooth thread finethreadsPin pinConsuming consumptionPinion pinionPath minordiameterRubber spring balataspringModified trapezoidal acceleration motion law modifiedtrapezoidalaccelerationmotionCorrection of motion law of sinusoidal accelerationmodifiedsineaccelerationmotionHelical gear HelicalGearCross key, hook head wedge key taperkeyLeakage leakageHarmonic gear harmonicgearHarmonic drive harmonicdrivingHarmonic generator harmonicgeneratorEquivalent spur gear of helical gear equivalentspurgearofthehelicalgearMandrel spindleTravel speed variation factorcoefficientoftravelspeedvariationTravel speed ratio coefficient advance-toreturn-timeratio Planetary gear unit planetarytransmissionPlanet gear planetgearPlanetary gear change gear planetaryspeedchangingdevices Planetary gear train planetarygeartrainForm closed cam mechanismpositive-driveorform-closedcammechanismVirtual reality virtualrealityVirtual reality technology virtualrealitytechnology, VRT Virtual reality design, virtualrealitydesign, VRDVirtual constraint redundantorpassiveconstraintAllowable imbalance quantity allowableamountofunbalance Allowable pressure angle allowablepressureangleAllowable stress allowablestress, permissiblestressCantilever structure cantileverstructureCantilever beam cantileverbeamCyclic power flow circulatingpowerloadRotational torque runningtorqueRotary seal rotatingsealRotational motion rotarymotionType selection typeselectionPressure pressurePressure center centerofpressureCompressor compressorCompressive stress compressivestressPressure angle pressureangleInlay couplings jawteethpositive-contactcouplingJacobi matrix JacobimatrixRocker rockerHydraulic transmission hydrodynamicdriveHydraulic coupler hydrauliccouplersLiquid spring liquidspringHydraulic stepless speed change hydraulicsteplessspeedchanges Hydraulic mechanism hydraulicmechanismGeneralized kinematic chain generalizedkinematicchainMoving follower reciprocatingfollowerMobile sub prismaticpair, slidingpairMobile joints prismaticjointMoving cam wedgecamProfit and loss work incrementordecrementworkStress amplitude stressamplitudeStress concentration stressconcentrationStress concentration factor factorofstressconcentration Stress diagram stressdiagramStress strain diagram stress-straindiagramOptimum design optimaldesignOilbottle cupI oilcanOil groove seal oilyditchsealHarmful resistance uselessresistanceBeneficial resistance usefulresistanceEffective pull effectivetensionEffective circumferential force effectivecircleforce Harmful resistance detrimentalresistanceCosine acceleration motion cosineaccelerationorsimpleharmonicmotionPreload preloadPrime mover primermoverRound belt roundbeltBelt drive roundbeltdriveArc tooth thickness circularthicknessCircular cylindrical worm hollowflankwormRounded radius filletradiusDisc friction clutch discfrictionclutchDisc brake discbrakePrime mover primemoverOriginal mechanism originalmechanismCircular gear circulargearCylindrical roller cylindricalrollerCylindrical roller bearings cylindricalrollerbearingCylindrical pair cylindricpairCylindrical cam stepping motion mechanism barrelcylindriccamCylindrical helical tension spring cylindroidhelical-coilextensionspringCylindrical helical torsion spring cylindroidhelical-coiltorsionspringCylindrical helical compression spring cylindroidhelical-coilcompressionspringCylindrical cam cylindricalcamCylindrical worm cylindricalwormCylindrical coordinate manipulator cylindricalcoordinatemanipulator Conical spiral torsion springconoidhelical-coilcompressionspringTapered roller taperedrollerTapered roller bearing taperedrollerbearingBevel gear mechanism bevelgearsTaper angle coneangleThe original drivinglinkBound constraintConstraint constraintconditionConstraint reaction force constrainingforceJump jerkJump curve jerkdiagramInversion of motion, kinematicinversionMotion scheme design kinematicpreceptdesign Kinematic analysis kinematicanalysisKinematic pair kinematicpairMoving component movinglinkKinematic diagram kinematicsketchKinematic chain kinematicchainMotion distortion undercuttingKinematic design kinematicdesignMotion cycle cycleofmotionKinematic synthesis kinematicsynthesisUneven coefficient of operation coefficientofvelocityfluctuationKinematic viscosity kenematicviscosityLoad loadLoad deformation curve load - DEFORMATIONCURVE Load deformation diagram load - deformationdiagram Narrow V band narrowVbeltFelt ring seal feltringsealThe generating method of generatingTensioning force tensionTensioner tensionpulleyVibration vibrationVibration torque shakingcoupleVibration frequency frequencyofvibration Amplitude amplitudeofvibrationTangent mechanism tangentmechanismForward kinematics directforwardkinematics Sinusoidal mechanism sinegenerator, scotchyoke Loom loomNormal stress and normal stress normalstress Brake brakeSpur gear SpurGearStraight bevel gear straightbevelgearRight triangle righttriangleCartesian coordinate manipulator CartesiancoordinatemanipulatorCoefficient of diameter diametralquotient Diameter series diameterseriesStraight profile hourglass worm gear hindleyworm Linear motion linearmotionStraight axis straightshaftMass massCentroid centerofmassExecution component executivelink workinglinkProduct of mass and diameter mass-radiusproduct Intelligent design, intelligentdesign, IDIntermediate plane mid-planeCenter distance centerdistanceVariation of center distance centerdistancechange Center wheel centralgearMedium diameter meandiameterTerminate the meshing point finalcontact, endofcontact Week Festival pitchPeriodic velocity fluctuation periodicspeedfluctuation Epicyclic gear train epicyclicgeartrainElbow mechanism togglemechanismAxis shaftBearing cap bearingcupBearing alloy bearingalloyBearing block bearingblockBearing height bearingheightBearing width bearingwidthBearing bore bearingborediameterBearing life bearinglifeBearing ring bearingringBearing outer diameter bearingoutsidediameterJournal JournalBush and bearing lining bearingbushShaft end retaining ring shaftendringCollar shaftcollarShoulder ShaftShoulderAxial angle shaftangleAxial axialdirectionAxial profile axialtoothprofileAxial equivalent dynamic load dynamicequivalentaxialload Axial equivalent static load staticequivalentaxialload Axial basic rated dynamic load basicdynamicaxialloadrating Axial basic rated static load basicstaticaxialloadrating Axial contact bearing axialcontactbearingAxial plane axialplaneAxial clearance axialinternalclearanceAxial load AxialLoadAxial load factor axialloadfactorAxial component axialthrustloadActive component, drivinglinkDriving gear drivinggearDriving pulley drivingpulleyRotating guide rod mechanism whitworthmechanismRevolute pair revoluteturningpairThe speed is swivelingspeed rotatingspeedRotating joint revolutejoint Rotating shaft revolvingshaftRotor rotorRotor balance balanceofrotor Assembly condition assemblycondition Bevel gear bevelgearCone top commonapexofconeCone distance conedistanceCone wheel bevelpulley bevelwheel。
机械工程专业英语教程(第2版)[施平主编][翻译]_lesson1
![机械工程专业英语教程(第2版)[施平主编][翻译]_lesson1](https://img.taocdn.com/s3/m/5728f673a417866fb84a8e09.png)
Basic Concept in MechanicsThe branch of scientific analysis which deals with motions , time , and forces is called mechanics and is made up of two parts , statics and dynamics , Statics deals with the analysis of stationary systems , i.e. , those in which time is not a factor , and dynamics deals with systems which change with time .对运动、时间和作用力做出科学分析的分支称为力学。
它由静力学和动力学两部分组成。
静力学对静止系统进行分析，即在其中不考虑时间这个因素，动力学对随时间而变化的系统进行分析。
When a number of bodies are connected together to form a group or system , the forces of action and reaction between any two of the connecting bodies are called constraint forces . These forces constrain the bodies to behave in a specific manner . Forces external to this system of bodies are called applied forces .当一些物体连接在一起形成一个组合体或者系统时，任何两个相连接的物体之间的作用力和反作用力被称为约束力。
这些力约束着各个物体，使其处于特定的状态。
从外部施加到这个物体的系统的力被称为外力。
机械加工外文翻译
附录附录1英文原文Basic Machining Operations and Cutting TechnologyBasic Machining OperationsMachine tools have evolved from the early foot-powered lathes of the Egyptians and John Wilkinson's boring mill. They are designed to provide rigid support for both the work piece and the cutting tool and can precisely control their relative positions and the velocity of the tool with respect to the work piece. Basically, in metal cutting, a sharpened wedge-shaped tool removes a rather narrow strip of metal from the surface of a ductile work piece in the form of a severely deformed chip. The chip is a waste product that is considerably shorter than the work piece from which it came but with a corresponding increase in thickness of the uncut chip. The geometrical shape of work piece depends on the shape of the tool and its path during the machining operation.Most machining operations produce parts of differing geometry. If a rough cylindrical work piece revolves about a central axis and the tool penetrates beneath its surface and travels parallel to the center of rotation, a surface of revolution is produced, and the operation is called turning. If a hollow tube is machined on the inside in a similar manner, the operation is called boring. Producing an external conical surface uniformly varying diameter is called taper turning, if the tool point travels in a path of varying radius, a contoured surface like that of a bowling pin can be produced; or, if the piece is short enough and the support is sufficiently rigid, a contoured surface could be produced by feeding a shaped tool normal to the axis of rotation. Short tapered or cylindrical surfaces could also be contour formed.Flat or plane surfaces are frequently required. They can be generated by radial turning or facing, in which the tool point moves normal to the axis of rotation. In other cases, it is more convenient to hold the work piece steady and reciprocate the tool across it in a series of straight-line cuts with a crosswise feed increment before each cutting stroke. This operation is called planning and is carried out on a shaper. For larger pieces it is easier to keep the tool stationary and draw the work piece under it as in planning. The tool is fed at each reciprocation. Contoured surfaces can be produced by using shaped tools.Multiple-edged tools can also be used. Drilling uses a twin-edged fluted tool for holes with depths up to 5 to 10 times the drill diameter. Whether thedrill turns or the work piece rotates, relative motion between the cutting edge and the work piece is the important factor. In milling operations a rotary cutter with a number of cutting edges engages the work piece. Which moves slowly with respect to the cutter. Plane or contoured surfaces may be produced, depending on the geometry of the cutter and the type of feed. Horizontal or vertical axes of rotation may be used, and the feed of the work piece may be in any of the three coordinate directions.Basic Machine ToolsMachine tools are used to produce a part of a specified geometrical shape and precise I size by removing metal from a ductile material in the form of chips. The latter are a waste product and vary from long continuous ribbons of a ductile material such as steel, which are undesirable from a disposal point of view, to easily handled well-broken chips resulting from cast iron. Machine tools perform five basic metal-removal processes: I turning, planning, drilling, milling, and grinding. All other metal-removal processes are modifications of these five basic processes. For example, boring is internal turning; reaming, tapping, and counter boring modify drilled holes and are related to drilling; bobbing and gear cutting are fundamentally milling operations; hack sawing and broaching are a form of planning and honing; lapping, super finishing. Polishing and buffing are variants of grinding or abrasive removal operations. Therefore, there are only four types of basic machine tools, which use cutting tools of specific controllable geometry: 1. lathes, 2. planers, 3. drilling machines, and 4. milling machines. The grinding process forms chips, but the geometry of the abrasive grain is uncontrollable.The amount and rate of material removed by the various machining processes may be I large, as in heavy turning operations, or extremely small, as in lapping or super finishing operations where only the high spots of a surface are removed.A machine tool performs three major functions: 1. it rigidly supports the work piece or its holder and the cutting tool; 2. it provides relative motion between the work piece and the cutting tool; 3. it provides a range of feeds and speeds usually ranging from 4 to 32 choices in each case.Speed and Feeds in MachiningSpeeds, feeds, and depth of cut are the three major variables for economical machining. Other variables are the work and tool materials, coolant and geometry of the cutting tool. The rate of metal removal and power required for machining depend upon these variables.The depth of cut, feed, and cutting speed are machine settings that must be established in any metal-cutting operation. They all affect the forces, the power, and the rate of metal removal. They can be defined by comparing them to the needle and record of a phonograph. The cutting speed (V) is represented by the velocity of- the record surface relative to the needle in the tone arm at any instant. Feed is represented by the advance of the needle radially inward perrevolution, or is the difference in position between two adjacent grooves. The depth of cut is the penetration of the needle into the record or the depth of the grooves.Turning on Lathe CentersThe basic operations performed on an engine lathe are illustrated. Those operations performed on external surfaces with a single point cutting tool are called turning. Except for drilling, reaming, and lapping, the operations on internal surfaces are also performed by a single point cutting tool.All machining operations, including turning and boring, can be classified as roughing, finishing, or semi-finishing. The objective of a roughing operation is to remove the bulk of the material as rapidly and as efficiently as possible, while leaving a small amount of material on the work-piece for the finishing operation. Finishing operations are performed to obtain the final size, shape, and surface finish on the work piece. Sometimes a semi-finishing operation will precede the finishing operation to leave a small predetermined and uniform amount of stock on the work-piece to be removed by the finishing operation.Generally, longer work pieces are turned while supported on one or two lathe centers. Cone shaped holes, called center holes, which fit the lathe centers are drilled in the ends of the work piece-usually along the axis of the cylindrical part. The end of the work piece adjacent to the tail stock is always supported by a tail stock center, while the end near the head stock may be supported by a head stock center or held in a chuck. The head stock end of the work piece may be held in a four-jaw chuck, or in a type chuck. This method holds the work piece firmly and transfers the power to the work piece smoothly; the additional support to the work piece provided by the chuck lessens the tendency for chatter to occur when cutting. Precise results can be obtained with this method if care is taken to hold the work piece accurately in the chuck.Very precise results can be obtained by supporting the work piece between two centers. A lathe dog is clamped to the work piece; together they are driven by a driver plate mounted on the spindle nose. One end of the Work piece is mecained;then the work piece can be turned around in the lathe to machine the other end. The center holes in the work piece serve as precise locating surfaces as well as bearing surfaces to carry the weight of the work piece and to resist the cutting forces. After the work piece has been removed from the lathe for any reason, the center holes will accurately align the work piece back in the lathe or in another lathe, or in a cylindrical grinding machine. The work piece must never be held at the head stock end by both a chuck and a lathe center. While at first thought this seems like a quick method of aligning the work piece in the chuck, this must not be done because it is not possible to press evenly with the jaws against the work piece while it is also supported by the center. The alignment provided by the center will not be maintained and the pressure of the jaws may damage the center hole, the lathe center, andperhaps even the lathe spindle. Compensating or floating jaw chucks used almost exclusively on high production work provide an exception to the statements made above. These chucks are really work drivers and cannot be used for the same purpose as ordinary three or four-jaw chucks.While very large diameter work pieces are sometimes mounted on two centers, they are preferably held at the headstock end by faceplate jaws to obtain the smooth power transmission; moreover, large lathe dogs that are adequate to transmit the power not generally available, although they can be made as a special. Faceplate jaws are like chuck jaws except that they are mounted on a faceplate, which has less overhang from the spindle bearings than a large chuck would have.Introduction of MachiningMachining as a shape-producing method is the most universally used and the most important of all manufacturing processes. Machining is a shape-producing process in which a power-driven device causes material to be removed in chip form. Most machining is done with equipment that supports both the work piece and cutting tool although in some cases portable equipment is used with unsupported work piece.Low setup cost for small Quantities. Machining has two applications in manufacturing. For casting, forging, and press working, each specific shape to be produced, even one part, nearly always has a high tooling cost. The shapes that may he produced by welding depend to a large degree on the shapes of raw material that are available. By making use of generally high cost equipment but without special tooling, it is possible, by machining; to start with nearly any form of raw material, so tong as the exterior dimensions are great enough, and produce any desired shape from any material. Therefore .machining is usually the preferred method for producing one or a few parts, even when the design of the part would logically lead to casting, forging or press working if a high quantity were to be produced.Close accuracies, good finishes. The second application for machining is based on the high accuracies and surface finishes possible. Many of the parts machined in low quantities would be produced with lower but acceptable tolerances if produced in high quantities by some other process. On the other hand, many parts are given their general shapes by some high quantity deformation process and machined only on selected surfaces where high accuracies are needed. Internal threads, for example, are seldom produced by any means other than machining and small holes in press worked parts may be machined following the press working operations.Primary Cutting ParametersThe basic tool-work relationship in cutting is adequately described by means of four factors: tool geometry, cutting speed, feed, and depth of cut.The cutting tool must be made of an appropriate material; it must be strong, tough, hard, and wear resistant. The tool s geometry characterized by planes and angles, must be correct for each cutting operation. Cutting speed is the rate at which the work surface passes by the cutting edge. It may be expressed in feet per minute.For efficient machining the cutting speed must be of a magnitude appropriate to the particular work-tool combination. In general, the harder the work material, the slower the speed.Feed is the rate at which the cutting tool advances into the work piece. "Where the work piece or the tool rotates, feed is measured in inches per revolution. When the tool or the work reciprocates, feed is measured in inches per stroke, Generally, feed varies inversely with cutting speed for otherwise similar conditions.The depth of cut, measured inches is the distance the tool is set into the work. It is the width of the chip in turning or the thickness of the chip in a rectilinear cut. In roughing operations, the depth of cut can be larger than for finishing operations.The Effect of Changes in Cutting Parameters on Cutting TemperaturesIn metal cutting operations heat is generated in the primary and secondary deformation zones and these results in a complex temperature distribution throughout the tool, work piece and chip. A typical set of isotherms is shown in figure where it can be seen that, as could be expected, there is a very large temperature gradient throughout the width of the chip as the work piece material is sheared in primary deformation and there is a further large temperature in the chip adjacent to the face as the chip is sheared in secondary deformation. This leads to a maximum cutting temperature a short distance up the face from the cutting edge and a small distance into the chip.Since virtually all the work done in metal cutting is converted into heat, it could be expected that factors which increase the power consumed per unit volume of metal removed will increase the cutting temperature. Thus an increase in the rake angle, all other parameters remaining constant, will reduce the power per unit volume of metal removed and the cutting temperatures will reduce. When considering increase in unreformed chip thickness and cutting speed the situation is more complex. An increase in undeformed chip thickness tends to be a scale effect where the amounts of heat which pass to the work piece, the tool and chip remain in fixed proportions and the changes in cutting temperature tend to be small. Increase in cutting speed; however, reduce the amount of heat which passes into the work piece and this increase the temperature rise of the chip m primary deformation. Further, the secondary deformation zone tends to be smaller and this has the effect of increasing the temperatures in this zone. Other changes in cutting parameters have virtually no effect on the power consumed per unit volume of metal removed and consequently have virtually no effect on the cutting temperatures. Since ithas been shown that even small changes in cutting temperature have a significant effect on tool wear rate it is appropriate to indicate how cutting temperatures can be assessed from cutting data.The most direct and accurate method for measuring temperatures in high -speed-steel cutting tools is that of Wright &. Trent which also yields detailed information on temperature distributions in high-speed-steel cutting tools. The technique is based on the metallographic examination of sectioned high-speed-steel tools which relates microstructure changes to thermal history.Trent has described measurements of cutting temperatures and temperature distributions for high-speed-steel tools when machining a wide range of work piece materials. This technique has been further developed by using scanning electron microscopy to study fine-scale microstructure changes arising from over tempering of the tempered martens tic matrix of various high-speed-steels. This technique has also been used to study temperature distributions in both high-speed -steel single point turning tools and twist drills.Wears of Cutting ToolDiscounting brittle fracture and edge chipping, which have already been dealt with, tool wear is basically of three types. Flank wear, crater wear, and notch wear. Flank wear occurs on both the major and the minor cutting edges. On the major cutting edge, which is responsible for bulk metal removal, these results in increased cutting forces and higher temperatures which if left unchecked can lead to vibration of the tool and work piece and a condition where efficient cutting can no longer take place. On the minor cutting edge, which determines work piece size and surface finish, flank wear can result in an oversized product which has poor surface finish. Under most practical cutting conditions, the tool will fail due to major flank wear before the minor flank wear is sufficiently large to result in the manufacture of an unacceptable component.Because of the stress distribution on the tool face, the frictional stress in the region of sliding contact between the chip and the face is at a maximum at the start of the sliding contact region and is zero at the end. Thus abrasive wear takes place in this region with more wear taking place adjacent to the seizure region than adjacent to the point at which the chip loses contact with the face. This result in localized pitting of the tool face some distance up the face which is usually referred to as catering and which normally has a section in the form of a circular arc. In many respects and for practical cutting conditions, crater wear is a less severe form of wear than flank wear and consequently flank wear is a more common tool failure criterion. However, since various authors have shown that the temperature on the face increases more rapidly with increasing cutting speed than the temperature on the flank, and since the rate of wear of any type is significantly affected by changes in temperature, crater wear usually occurs at high cutting speeds.At the end of the major flank wear land where the tool is in contact with the uncut work piece surface it is common for the flank wear to be more pronounced than along the rest of the wear land. This is because of localised effects such as a hardened layer on the uncut surface caused by work hardening introduced by a previous cut, an oxide scale, and localised high temperatures resulting from the edge effect. This localised wear is usually referred to as notch wear and occasionally is very severe. Although the presence of the notch will not significantly affect the cutting properties of the tool, the notch is often relatively deep and if cutting were to continue there would be a good chance that the tool would fracture.If any form of progressive wear allowed to continue, dramatically and the tool would fail catastrophically, i. e. the tool would be no longer capable of cutting and, at best, the work piece would be scrapped whilst, at worst, damage could be caused to the machine tool. For carbide cutting tools and for all types of wear, the tool is said to have reached the end of its useful life long before the onset of catastrophic failure. For high-speed-steel cutting tools, however, where the wear tends to be non-uniform it has been found that the most meaningful and reproducible results can be obtained when the wear is allowed to continue to the onset of catastrophic failure even though, of course, in practice a cutting time far less than that to failure would be used. The onset of catastrophic failure is characterized by one of several phenomena, the most common being a sudden increase in cutting force, the presence of burnished rings on the work piece, and a significant increase in the noise level.Mechanism of Surface Finish ProductionThere are basically five mechanisms which contribute to the production of a surface which have been machined. These are:(l) The basic geometry of the cutting process. In, for example, single point turning the tool will advance a constant distance axially per revolution of the workpiecc and the resultant surface will have on it, when viewed perpendicularly to the direction of tool feed motion, a series of cusps which will have a basic form which replicates the shape of the tool in cut.(2) The efficiency of the cutting operation. It has already been mentioned that cutting with unstable built-up-edges will produce a surface which contains hard built-up-edge fragments which will result in a degradation of the surface finish. It can also be demonstrated that cutting under adverse conditions such as apply when using large feeds small rake angles and low cutting speeds, besides producing conditions which lead to unstable built-up-edge production, the cutting process itself can become unstable and instead of continuous shear occurring in the shear zone, tearing takes place, discontinuous chips of uneven thickness are produced, and the resultant surface is poor. This situation is particularly noticeable when machining very ductile materials such as copper and aluminum.(3) The stability of the machine tool. Under some combinations of cutting conditions; work piece size, method of clamping ,and cutting tool rigidity relative to the machine tool structure, instability can be set up in the tool which causes it to vibrate. Under some conditions this vibration will reach and maintain steady amplitude whilst under other conditions the vibration will built up and unless cutting is stopped considerable damage to both the cutting tool and work piece may occur. This phenomenon is known as chatter and in axial turning is characterized by long pitch helical bands on the work piece surface and short pitch undulations on the transient machined surface.(4)The effectiveness of removing swarf. In discontinuous chip production machining, such as milling or turning of brittle materials, it is expected that the chip (swarf) will leave the cutting zone either under gravity or with the assistance of a jet of cutting fluid and that they will not influence the cut surface in any way. However, when continuous chip production is evident, unless steps are taken to control the swarf it is likely that it will impinge on the cut surface and mark it. Inevitably, this marking besides looking.(5)The effective clearance angle on the cutting tool. For certain geometries of minor cutting edge relief and clearance angles it is possible to cut on the major cutting edge and burnish on the minor cutting edge. This can produce a good surface finish but, of course, it is strictly a combination of metal cutting and metal forming and is not to be recommended as a practical cutting method. However, due to cutting tool wear, these conditions occasionally arise and lead to a marked change in the surface characteristics.Limits and TolerancesMachine parts are manufactured so they are interchangeable. In other words, each part of a machine or mechanism is made to a certain size and shape so will fit into any other machine or mechanism of the same type. To make the part interchangeable, each individual part must be made to a size that will fit the mating part in the correct way. It is not only impossible, but also impractical to make many parts to an exact size. This is because machines are not perfect, and the tools become worn. A slight variation from the exact size is always allowed. The amount of this variation depends on the kind of part being manufactured. For examples part might be made 6 in. long with a variation allowed of 0.003 (three-thousandths) in. above and below this size. Therefore, the part could be 5.997 to 6.003 in. and still be the correct size. These are known as the limits. The difference between upper and lower limits is called the tolerance.A tolerance is the total permissible variation in the size of a part.The basic size is that size from which limits of size arc derived by the application of allowances and tolerances.Sometimes the limit is allowed in only one direction. This is known as unilateral tolerance.Unilateral tolerancing is a system of dimensioning where the tolerance (that is variation) is shown in only one direction from the nominal size. Unilateral tolerancing allow the changing of tolerance on a hole or shaft without seriously affecting the fit.When the tolerance is in both directions from the basic size it is known as a bilateral tolerance (plus and minus).Bilateral tolerancing is a system of dimensioning where the tolerance (that is variation) is split and is shown on either side of the nominal size. Limit dimensioning is a system of dimensioning where only the maximum and minimum dimensions arc shown. Thus, the tolerance is the difference between these two dimensions.Surface Finishing and Dimensional ControlProducts that have been completed to their proper shape and size frequently require some type of surface finishing to enable them to satisfactorily fulfill their function. In some cases, it is necessary to improve the physical properties of the surface material for resistance to penetration or abrasion. In many manufacturing processes, the product surface is left with dirt .chips, grease, or other harmful material upon it. Assemblies that are made of different materials, or from the same materials processed in different manners, may require some special surface treatment to provide uniformity of appearance.Surface finishing may sometimes become an intermediate step processing. For instance, cleaning and polishing are usually essential before any kind of plating process. Some of the cleaning procedures are also used for improving surface smoothness on mating parts and for removing burrs and sharp corners, which might be harmful in later use. Another important need for surface finishing is for corrosion protection in a variety of: environments. The type of protection procedure will depend largely upon the anticipated exposure, with due consideration to the material being protected and the economic factors involved.Satisfying the above objectives necessitates the use of main surface-finishing methods that involve chemical change of the surface mechanical work affecting surface properties, cleaning by a variety of methods, and the application of protective coatings, organic and metallic.In the early days of engineering, the mating of parts was achieved by machining one part as nearly as possible to the required size, machining the mating part nearly to size, and then completing its machining, continually offering the other part to it, until the desired relationship was obtained. If it was inconvenient to offer one part to the other part during machining, the final work was done at the bench by a fitter, who scraped the mating parts until the desired fit was obtained, the fitter therefore being a 'fitter' in the literal sense. J It is obvious that the two parts would have to remain together, and m the event of one having to be replaced, the fitting would have to be done all over again. In these days, we expect to be able to purchase a replacement fora broken part, and for it to function correctly without the need for scraping and other fitting operations.When one part can be used 'off the shelf' to replace another of the same dimension and material specification, the parts are said to be interchangeable. A system of interchangeability usually lowers the production costs as there is no need for an expensive, 'fiddling' operation, and it benefits the customer in the event of the need to replace worn parts.Automatic Fixture DesignTraditional synchronous grippers for assembly equipment move parts to the gripper centre-line, assuring that the parts will be in a known position after they arc picked from a conveyor or nest. However, in some applications, forcing the part to the centre-line may damage cither the part or equipment. When the part is delicate and a small collision can result in scrap, when its location is fixed by a machine spindle or mould, or when tolerances are tight, it is preferable to make a gripper comply with the position of the part, rather than the other way around. For these tasks, Zaytran Inc. Of Elyria, Ohio, has created the GPN series of non- synchronous, compliant grippers. Because the force and synchronizations systems of the grippers are independent, the synchronization system can be replaced by a precision slide system without affecting gripper force. Gripper sizes range from 51b gripping force and 0.2 in. stroke to 40Glb gripping force and 6in stroke. GrippersProduction is characterized by batch-size becoming smaller and smaller and greater variety of products. Assembly, being the last production step, is particularly vulnerable to changes in schedules, batch-sizes, and product design. This situation is forcing many companies to put more effort into extensive rationalization and automation of assembly that was previouslyextensive rationalization and automation of assembly that was previously the case. Although the development of flexible fixtures fell quickly behind the development of flexible handling systems such as industrial robots, there are, nonetheless promising attempts to increase the flexibility of fixtures. The fact that fixtures are the essential product - specific investment of a production system intensifies the economic necessity to make the fixture system more flexible.Fixtures can be divided according to their flexibility into special fixtures, group fixtures, modular fixtures and highly flexible fixtures. Flexible fixtures are characterized by their high adaptability to different work pieces, and by low change-over time and expenditure.There are several steps required to generate a fixture, in which a work piece is fixed for a production task. The first step is to define the necessary position of the work piece in the fixture, based on the unmachined or base pan, and the working features. Following this, a combination of stability planes must be selected. These stability planes constitute the fixture configuration in which the work piece is fixed in the defined position, all the forces or torques are compensated,。
外文翻译---铁路系统接触网中集电板碳合金的含量对其与接触线磨影响
附录1 外文资料翻译A1.1 译文铁路系统接触网中集电板碳合金的含量对其与接触线磨影响本文主要是对发生在接触网中接触线和集电板之间磨损情况的研究，它们之间的磨损由机械和电气两个方面引起。
这方面的研究对设施的维修成本和受电弓与接触线的工作寿命有着密切的关系。
由于接触网中维修机车和基础设施方面的重要性，在过去几十年世界上一直对这个问题十分重视。
为了探讨机械和电气两方面引起的接触线和滑板之间的磨损，在米兰设计并安装了一种新型的测试装置。
一系列的实验测试已经完成，其中涉及了多种材料的集电板和在不同转速与电流强度的接触条件。
研究中涉及到了3kV直流线路所需要的各种不同结构的集电板。
研究中发现集电板中的铜和碳合金的不同含量对滑板与接触线的磨损有着很大的影响。
前言高速铁路运输系统的发展意味着对电能需求的增加，但是从目前通过受电弓在架空线（接触网）获取电能的水平来看，就需要受电弓集电板具有较高的工作性能。
这个问题不仅仅由于高速列车的原因，而且与线路的容量和货运列车的长期运行有关。
意大利铁路系统决定把所有的铜材料的集电板换为Kasperowski型，随后又把碳合金用于集电板，这些在线路材料方面的改进都是对3kv直流线路的挑战。
当接触线上的电流达到1000A以上时就会由于产生的机械热加重受电弓集电板的损坏。
众所周知，接触线和受电弓集电板的磨损主要取决于以下几个因素：接触线材料的类型，运行条件（滑动速度接触力电流强度等）以及它们之间是否发出电火花和电弧等。
在Klapas et al.和Becker的的著作中，对以上提到的决定线路磨损程度的各种原因以及它们之间的相互影响都有说明。
基于简单方便起见，在集电板和接触线之间产生的磨损可以分为两种：一种是由于机械摩擦引起的磨损，另外一种是由于电火花引起的磨损，这两者相互作用并影响。
特别是越来越多的磨损不仅和线路的电流强度有关，而且和弓网之间的接触压力有关，同时和火花强度有关的磨损也随着接触压力的增大而加重。
机械设计制造及其自动化专业英语课文翻译-Unit1-9
U 1The use of metals has always a key factor in the development of the social systems of man. Of the roughly ['rʌfl ɪ] 100 basic elements of which all matter is composed, about half are classified as metals.金属的开发利用在人类社会系统的发展中扮演了了重要的角色，世界的物质大概由100种基本元素构成，其中一半是金属元素。
The distinction[dɪ'stɪŋkʃən] between a metal and a nonmetal is not always clear cut. The most basic definition centers around the type of bonding existing between the atoms of the element, and around the characteristics [,kærəkt ə'ristiks] of certain of the electrons[ɪ'lɛk,trɑn] associated with these atoms.金属与非金属的区分不是十分的清晰，最重要（基本）的在于元素原子之间的连接形式以及和原子相关联的电子的确定特性。
in a more practical['præktikəl] way, however, a metal can be defined as an element which has a particular package of properties.然而，在更多的实践当中，金属定义为具有一种整体特性的元素。