矫直机中英文对照外文翻译文献
机械加工介绍外文文献翻译、中英文翻译、外文翻译
题目机械加工介绍学院专业班级姓名学号指导教师Machining Processing Introduction1 LatheLathes are machine tools designed primarily to do turning, facing and bori ng, Very little turning is done on other types of machine tools, and none can do it with equal facility. Because lathes also can do drilling and reaming, their versatility permits several operations to be done with a single setup of the work piece. Consequently, more lathes of various types are used in manufacturing than any other machine tool.The essential components of a lathe are the bed, headstock assembly, tailstock assembly, and the leads crew and feed rod.The bed is the backbone of a lathe. It usually is made of well normalized or aged gray or nodular cast iron and provides s 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. Som 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, they are precision-machined to assure accuracy of alignment. On most modern lathes the way are surface-hardened to resist wear and abrasion, but precaution should be taken 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 headstock is mounted in a foxed position on the inner ways, usually at the left end of the bed. It provides a powered means of rotating the word at various speeds. Essentially, it consists 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 8 to 18 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. The spindle has a hole extending through its length through which long bar stock can be fed. The size of maximum size of bar stock that can be machined when the material must be fed through spindle.The tailsticd assembly consists, essentially, of three parts. A lower casting fits on the inner ways of the bed and can slide longitudinally thereon, with 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, to permit aligning the assembly is the tailstock quill. This is hollow steel cylinder, usually about 51 to 76mm (2to 3 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 size of a lathe is designated by two dimensions. The first is known as theswing. This is the maximum diameter of work that can be rotated on a lathe. It is approximately twice the distance between the line connecting the lathe centers and the nearest point on the ways, the second size dimension is the maximum distance between centers. The swing thus indicates the maximum work piece diameter that can be turned in the lathe, while the distance between centers indicates the maximum length of work piece that can be mounted between centers.Engine lathes are the type most frequently used in manufacturing. They are heavy-duty machine tools with all the components described previously and have power drive for all tool movements except on the compound rest. They commonly range in size from 305 to 610 mm(12 to 24 inches)swing and from 610 to 1219 mm(24 to 48 inches) center distances, but swings up to 1270 mm(50 inches) and center distances up to 3658mm(12 feet) are not uncommon. Most have chip pans and a built-in coolant circulating system. Smaller engine lathes-with swings usually not over 330 mm (13 inches) –also are available in bench type, designed for the bed to be mounted on a bench on a bench or cabinet.Although engine lathes are versatile and very useful, because of the time required for changing and setting tools and for making measurements on the work piece, thy are not suitable for quantity production. Often the actual chip-production tine is less than 30% of the total cycle time. In addition, a skilled machinist is required for all the operations, and such persons are costly and often in short supply. However, much of the operator’s time is consumed by simple, repetitious adjustments and in watching chips being made. Consequently, to reduce or eliminate the amountof skilled labor that is required; turret lathes, screw machines, and other types of semiautomatic and automatic lathes have been highly developed and are widely used in manufacturing.2 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 ere manually operated and controlled. Among the many limitations associated with manual control machine tools, perhaps none is more prominent than the 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 writes a program that issues operational instructions to the machine tool. For a machine 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:Electrical discharge machining, Laser cutting, Electron beam welding.Numerical control has also made machine tools more versatile than their manually operated predecessors. An NC machine tool can automatically produce a wide 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 tolls and processes.Like so many advanced technologies, NC was born in the laboratories of the Massachusetts Institute of Technology. The concept of NC was developed in the early 1950s with funding provided by the U.S. Air Force. In its earliest stages, NC machines were able to made 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 the 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 fur ther development from those used today. The machines had hardwired logic circuits. The instructional programs were written on punched paper, which was later to be replaced by magnetic plastic tape. Atape 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 was 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 successive time a part was produced on a machine tool; the paper tape carrying the programmed instructions had to be rerun 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 tines. 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 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 the paper tape, 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 was 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 areality and soon solved the problems 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 an 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 on a host computer. When the host computer goes down, the machine tools also experience downtime. This problem led to the development of computer numerical control.3 TurningThe engine lathe, one of the oldest metal removal machines, has a number of useful and highly desirable attributes. Today these lathes are used primarily in small shops where smaller quantities rather than large production runs are encountered.The engine lathe has been replaced in today’s production shops by a wide variety of automatic lathes such as automatic of single-point tooling for maximum metal removal, and the use of form tools for finish on a par with the fastest processing equipment on the scene today.Tolerances for the engine lathe depend primarily on the skill of the operator. The design engineer must be careful in using tolerances of an experimental part that has been produced on the engine lathe by a skilled operator. In redesigning an experimental part for production, economical tolerances should be used.Turret Lathes Production machining equipment must be evaluated now, more than ever before, this criterion for establishing the production qualification of a specific method, the turret lathe merits a high rating.In designing for low quantities such as 100 or 200 parts, it is most economical to use the turret lathe. In achieving the optimum tolerances possible on the turrets lathe, the designer should strive for a minimum of operations.Automatic Screw Machines Generally, automatic screw machines fall into several categories; single-spindle automatics, multiple-spindle automatics and automatic chucking machines. Originally designed for rapid, automatic production of screws and similar threaded parts, the automatic screw machine has long since exceeded the confines of this narrow field, and today plays a vital role in the mass production of a variety of precision parts. Quantities play an important part in the economy of the parts machined on the automatic screw machine. Quantities less than on the automatic screw machine. The cost of the parts machined can be reduced if the minimum economical lot size is calculated and the proper machine is selected for these quantities.Automatic Tracer Lathes Since surface roughness depends greatly on material turned, tooling , and feeds and speeds employed, minimum tolerances that can be held on automatic tracer lathes are not necessarily the most economical tolerances.In some cases, tolerances of 0.05mm are held in continuous production using but one cut . groove width can be held to 0.125mm on some parts. Bores and single-point finishes can be held to 0.0125mm. On high-production runs where maximum output is desirable, a minimum tolerance of 0.125mm is economical on both diameter and length of turn.机械加工介绍1.车床车床主要是为了进行车外圆、车端面和镗孔等项工作而设计的机床。
直流电动机中英文对照外文翻译文献
中英文对照外文翻译文献(文档含英文原文和中文翻译)外文文献：DC Motor CalculationsOverviewNow that we have a good understanding of dc generators, we can begin our study of dc motors. Direct-current motors transform electrical energy into mechanical energy. They drive devices such as hoists, fans, pumps, calendars, punch-presses, and cars. These devices may have a definite torque-speed characteristic (such as a pump or fan) or a highly variable one (such as a hoist or automobile). The torque-speed characteristic of the motor must be adapted to the type of the load it has to drive, and this requirement has given rise to three basic types of motors: 1.Shunt motors 2. Series motors 3. Compound motors Direct-current motors are seldom used in ordinary industrial applications because all electric utility systems furnish alternating current. However, for special applications such as in steel mills, mines, and electric trains, it is sometimes advantageous to transform the alternating current into direct current in order to use dc motors. The reason is that the torque-speed characteristics of dc motors can be varied over a wide range while retaining high efficiency. Today, this general statement can be challenged because the availability of sophisticated electronic drives has made it possible to use alternating current motors for variable speed applications. Nevertheless, there are millions of dc motors still in service and thousands more are being produced every year.Counter-electromotive force (cemf)Direct-current motors are built the same way as generators are; consequently, a dc machine can operate either as a motor or as a generator. To illustrate, consider a dc generator in which the armature, initially at rest, is connected to a dc source E s by means of a switch (Fig. 5.1). The armature has a resistance R, and the magnetic field is created by a set of permanent magnets.As soon as the switch is closed, a large current flows in the armature because its resistance is very low. The individual armature conductors are immediately subjected to a force because they are immersed in the magnetic field created by the permanent magnets. These forces add upto produce a powerful torque, causing the armature to rotate.Figure 5.1 Starting a dc motor across the line.On the other hand, as soon as the armature begins to turn, a second phenomenon takes place: the generator effect. We know that a voltage E o is induced in the armature conductors as soon as they cut a magnetic field (Fig. 5.2). This is always true, no matter what causes the rotation. The value and polarity of the induced voltage are the same as those obtained when the machine operates as a generator. The induced voltage E o is therefore proportional to the speed of rotation n of the motor and to the flux F per pole, as previously given by Eq. 5.1:E o = Zn F/60 (5.1)As in the case of a generator, Z is a constant that depends upon the number of turns on the armature and the type of winding. For lap windings Z is equal to the number of armature conductors.In the case of a motor, the induced voltage E o is called counter-electromotive force (cemf) because its polarity always acts against the source voltage E s. It acts against the voltage in the sense that the net voltage acting in the series circuit of Fig. 5.2 is equal to (E s - Eo) volts and not (E s + E o) volts.Figure 5.2 Counter-electromotive force (cemf) in a dc motor.Acceleration of the motorThe net voltage acting in the armature circuit in Fig. 5.2 is (E s- E o) volts. The resulting armature current /is limited only by the armature resistance R, and soI = (E s- E o)IR (5.2)When the motor is at rest, the induced voltage E o= 0, and so the starting current isI = E s/RThe starting current may be 20 to 30 times greater than the nominal full-load current of the motor. In practice, this would cause the fuses to blow or the circuit-breakers to trip. However, if they are absent, the large forces acting on the armature conductors produce a powerful starting torque and a consequent rapid acceleration of the armature.As the speed increases, the counter-emf E o increases, with the result that the value of (E s—E o)diminishes. It follows from Eq. 5.1 that the armature current / drops progressively as the speed increases.Although the armature current decreases, the motor continues to accelerate until it reaches a definite, maximum speed. At no-load this speed produces a counter-emf E o slightly less than the source voltage E s. In effect, if E o were equal to E s the net voltage (E s—E o) would become zero and so, too, would the current /. The driving forces would cease to act on the armature conductors, and the mechanical drag imposed by the fan and the bearings would immediately cause the motor to slow down. As the speed decreases the net voltage (E s—E o) increases and so does the current /. The speed will cease to fall as soon as the torque developed by the armature current is equal to the load torque. Thus, when a motor runs at no-load, the counter-emf must be slightly less than E s so as to enable a small current to flow, sufficient to produce the required torque.Mechanical power and torqueThe power and torque of a dc motor are two of its most important properties. We now derive two simple equations that enable us to calculate them.1. According to Eq. 5.1 the cemf induced in a lap-wound armature is given byE o = Zn F/60Referring to Fig. 5.2, the electrical power P a supplied to the armature is equal to the supply voltage E s multiplied by the armature current I:P a = E s I (5.3)However, E s is equal to the sum of E o plus the IR drop in the armature:E s = E o + IR (5.4)It follows thatP a= E s I= (E o + IR)I=E o I + I2R (5.5)The I2R term represents heat dissipated in the armature, but the very important term E o I is the electrical power that is converted into mechanical power. The mechanical power of the motor is therefore exactly equal to the product of the cemf multiplied by the armature currentP = E o I (5.6)whereP = mechanical power developed by the motor [W]E o= induced voltage in the armature (cemf) [V]I = total current supplied to the armature [A]2. Turning our attention to torque T, we know that the mechanical power P is given by the expressionP = nT/9.55 (5.7)where n is the speed of rotation.Combining Eqs. 5.7,5.1, and 5.6, we obtainnT/9.55 = E o I= ZnFI/60and soT =Z F I/6.28The torque developed by a lap-wound motor is therefore given by the expressionT =Z F I/6.28 (5.8)whereT = torque [N×m]Z = number of conductors on the armatureF = effective flux per pole [Wb]*/ = armature current [A]6.28 = constant, to take care of units[exact value = 2p]Eq. 5.8shows that we can raise the torque of a motor either by raising the armature current or by raising the flux created by the poles.Speed of rotationWhen a dc motor drives a load between no-load and full-load, the IR drop due to armature resistance is always small compared to the supply voltage E s. This means that the counter-emf E s is very nearly equal to E s.On the other hand, we have already seen that Eo may be expressed by the equationE o = Zn F/60Replacing E o by E s we obtainE s = Zn F/60That is,wheren = speed of rotation [r/min]E s = armature voltage [V]Z = total number of armature conductorsThis important equation shows that the speed of the motor is directly proportional to the armature supply voltage and inversely proportional to the flux per pole. We will now study how this equation is applied.Armature speed controlAccording to Eq. 5.8, if the flux per pole F is kept constant (permanent magnet field or field with fixed excitation), the speed depends only upon the armature voltage E s. By raising or lowering E s the motor speed will rise and fall in proportion.In practice, we can vary E s by connecting the motor armature M to a separately excited variable-voltage dc generator G . The field excitation of the motor is kept constant, but the generator excitation I x can be varied from zero to maximum and even reversed. The generator output voltage E s can therefore be varied from zero to maximum, with either positive or negative polarity. Consequently, the motor speed can be varied from zero to maximum in either direction. Note that the generator is driven by an ac motor connected to a 3-phase line. This method of speed control, known as the Ward-Leonard system, is found in steel mills, high-rise elevators, mines, and paper mills.In modem installations the generator is often replaced by a high-power electronic converter that changes the ac power of the electrical utility to dc, by electronic means.What happens to the dc power received by generator G? When G receives electric power, it operates as a motor, driving its own ac motor as an asynchronous generator!* As a result, ac power is fed back into the line that normally feeds the ac motor. The fact that power can be recovered this way makes the Ward-Leonard system very efficient, and constitutes another of its advantages.Rheostat Speed ControlAnother way to control the speed of a dc motor is to place a rheostat in series with the armature . The current in the rheostat produces a voltage drop which subtracts from the fixed source voltage E s, yielding a smaller supply voltage across the armature. This method enables us to reduce the speed below its nominal speed. It is only recommended for small motors because a lot of power and heat is wasted in the rheostat, and the overall efficiency is low. Furthermore, thespeed regulation is poor, even for a fixed setting of the rheostat. In effect, the IR drop across the rheostat increases as the armature current increases. This produces a substantial drop in speed with increasing mechanical load.中文译文：直流电动机的计算概述现在，我们对直流发电机有一个很好的了解，我们可以开始对直流电动机的研究了。
机械加工外文翻译、中英文翻译、机械类外文文献翻译
外文原文：Machining TurningThe engine lathe, one of the oldest metal removal machines, has a number of useful and highly desirable attributes. Today these lathes are used primarily in small shops where smaller quantities rather than large production runs are encountered.The engine lathe has been replaced in today’s production shops by a wide variety of automatic lathes such as automatic tracer lathes, turret lathes, and automatic screw machines. All the advantages of single-point tooling for maximum metal removal, and the use of form tools for finished on a par with the fastest processing equipment on the scene today.Tolerances for the engine lathe depend primarily on the skill of the operator. The design engineer must be careful in using tolerances of an experimental part that has been produced on the engine lathe by a skilled operator. In redesigning an experimental part for production, economical tolerances should be used.Turret LathesProduction machining equipment must be evaluated now, more than ever before, in terms of ability to repeat accurately and rapidly. Applying this criterion for establishing the production qualification of a specific method, the turret lathe merits a high rating.In designing for low quantities such as 100 or 200 parts, it is most economical to use the turret lathe. In achieving the optimum tolerances possible on the turret lathe, the designer should strive for a minimum of operations.Automatic Screw MachinesGenerally, automatic screw machines fall into several categories; single-spindle automatics, multiple-spindle rapid, automatic chucking machines. Originally designed for rapid, automatic production of screws and similar threaded parts, the narrow field, and today plays a vital role in the mass production of a variety of precision parts. Quantities play an important part in the economy of the parts machined on the automatic screw machine. The cost of the parts machined can be reduced if the minimum economical lot size is calculated and the proper machine is selected for these quantities.Automatic Tracer LathesSince surface roughness depends greatly upon material turned, tooling, and feeds and speeds employed, minimum tolerances that can be held on automatic tracer lathes are not necessarily the most economical tolerances.In some cases, tolerances of ±0.05mm are held in continuous production using but one cut. Groove width can be held to ±0.0125mm on some parts. Bores and single-point finishes can be held to ±0.0125mm. On high-production runs where maximum output is desirable, a minimum tolerance of ±0.125mm is economical on both diameter and length of turn.MillingWith the exceptions of turning and drilling, milling is undoubtedly the most widely used method of removing metal. Well suited and readily adapted to the economical production of any quantity of parts, the almost unlimited versatility of milling process merits the attention and consideration of designers seriously with the manufacture of their product.As in any other process, parts that have to be milled should be designed with economical tolerances that can be achieved in production mill. If the part is designed with tolerances finer than necessary, additional operations will have to be added to achieve these tolerances-and this will increase the cost of the part.GrindingGrinding is one of the most widely used methods of finishing parts to extremely close tolerances and fine surface finishes. Currently, there are grinders for almost every type of grinding machine required. Where processing costs are excessive, parts redesigned to worthwhile. For example, wherever possible the production economy of centerless grinding should be taken advantage of by proper design consideration.Although grinding is usually considered a finishing operation, it is often employed as a complete machining process on work which can be ground down from rough condition without being turned or otherwise machined. Thus many types of forgings and other parts are finished completely with the grinding wheel at appreciable savings of time and expense.Classes of grinding machines include the following: cylindrical grinders, centerless grinders, internal grinders, surface grinders, and tool expense.The cylindrical and centerless grinders or taper work; thus splines, shafts, and similar parts are ground on cylindrical machines either of the common-center type orthe centerless machine.Thread grinders are used for grinding precision threads for thread gages, and threads on precision parts where the concentricity between the diameter of the shaft and pitch diameter of thread must be held to close tolerances.The internal grinders are used for grinding of precision holes, cylinder bores, and similar operations where bores of all kinds are to be finished.The surface grinders are for finishing all kinds of flat work, or work with plain surfaces which may be operated upon either by the edge of a wheel or by the face of a grinding wheel. These machines may have reciprocating or rotating tables.译文：机械加工金属切削机床中最早的一种是普通车床，当今仍有许多有用的特性。
数控机床改造中英文对照外文翻译文献
中英文对照外文翻译文献(文档含英文原文和中文翻译)原文:The Numerical Control Engine Bed TransformsHarvey B.M ackey First numerical control system development summary brief hi story and tendency.In 1946 the first electronic accounting machine was born the world,this indicated the humanity created has been possib le to strengthen and partially to replace the mental labor the tool. It with the humanity these which in the agricultu re, the industry society created only is strengthens the phy sical labor the tool to compare, got up the quantitive leap ,entered the information society for the humanity to laythe foundation.After 6 years, in 1952, computer technology applied to t he engine bed , the first numerical control engine bed were born in US. From this time on, the traditional engine bed has had the archery target change. Since nearly half centu ry, the numerical control system has experienced two stages and six generation of development.1.1 Numerical control (NC) stage (1952 ~ 1970)The early computer operating speed is low, was not big to then science computation and the data processing influence ,but could not adapt the engine bed real-time control reques t.The people can not but use numeral logic circuit "to buil d"to become an engine bed special purpose computer to take the numerical control system, is called the hardware connecti onnumerical control (HARD-WIRED NC), Jian Chengwei numerical c ontrol (NC). Along with the primary device development, this stage has had been through repeatedly three generations, na mely 1952 first generation of -- electron tube; 1959 second generation of -- transistor; 1965 third generation -- small scale integration electric circuit.1.2 Computer numerical control (CNC) stage (in 1970 ~ presen t)In 1970, the general minicomputer already appeared and th e mass production. Thereupon transplants it takes the numeric al control system the core part, from this time on entered the computer numerical control (CNC) the stage ("which should have computer in front of the general" two characters to ab breviate). In 1971, American INTEL Corporation in the world first time the computer two most cores part -- logic units and the controller, used the large scale integrated circuit technology integration on together the chip, called it the m icroprocessor (MICROPROCESSOR), also might be called the centr al processing element (to be called CPU).The microprocessor is applied to 1974 in the numerical c ontrol system. This is because minicomputer function too stro ng, controlled an engine bed ability to have wealthily (therefore once uses in controlling the multi- Taiwan engine bed at that time, called it group control), was inferior to use d the microprocessor economy to be reasonable. Moreover then small machine reliability was not ideal. The early microproce ssor speed and the function although insufficiently are also high, but may solve through the multi-processor structure. Because the microprocessor is the general-purpose calculator core part, therefore still was called the computer numerical control.In 1990, PC machine (personal computer, domestic custom had called microcomputer) the performance has developed tothe very high stage, may satisfiedly take the numerical cont rol system core part the request. Thenumerical control system henceforth entered based on the PC stage. In brief, the computer numerical control stage has also experienced three generations. Namely 1970 fourth generat ion of -- minicomputer; 1974 five dynasties -- microprocessor and 1990 sixth generation -- (overseas was called PC-BASED) based on PC.Also must point out, although overseas already renamed as the computer numerical control (namely CNC).Also must point out, although overseas already renamed as the computer numerical control (namely CNC), but our countr y still the custom called the numerical control (NC). Theref ore we daily say "numerical control", the materially already was refers to "computer numerical control".1.3 the numerical control future will develop tendency1.3.1 open style continues to, to develop based on the PC sixth generation of directionThe software and hardware resources has which based on P C are rich and so on the characteristic, the more numerical controls serial production factory can step onto this path. Uses PC machine to take at least its front end machine, pr ocesses the man-machine contact surface, the programming, the association .Question and so on net correspondence, undertakes the num erical control duty by the original system. PC machine has the friendly man-machine contact surface, will popularize to all numerical controls system. The long-distance communication, the long-distance diagnosis and the service will be more common.1.3.2 approaches and the high accuracy developmentThis is adapts the engine bed to be high speed and the high accuracy direction need to develop.1.3.3 develops to the intellectualized directionAlong with the artificial intelligence in the computer do mainunceasing seepage and the development, the numerical control system intellectualized degree unceasingly will enhance.(1) applies the adaptive control technologyThe numerical control system can examine in the process some important information, and the automatic control system related parameter, achieves the improvement system running sta tus the goal.(2) introduces the expert system instruction processingThe skilled worker and expert's experience, the processing general rule and the special rule store in the system, take the craft parameter database as the strut, the establishmenthas the artificial intelligence the expert system.(3)introduces the breakdown to diagnose the expert system(4) intellectualized numeral servo driveMay through the automatic diagnosis load, but the automat ic control parameter, causes the actuation system to obtain the best movement.Second, engine bed numerical control transformation necessi ty.2.1 microscopic looks at the transformation the necessityFrom on microscopic looked below that, the numerical cont rol engine bed has the prominent superiority compared to the traditional engine bed, moreover these superiority come from the computer might which the numerical control system contain s.2.1.1 may process the traditional engine bed cannot proce ss the curve, the curved surface and so on the complex com ponents.Because the computer has the excellent operation ability, may the instant accurately calculate each coordinate axis ins tant to be supposed the movement physiological load of exerc ise, therefore may turn round thesynthesis complex curve or the curved surface.2.1.2 may realize the processing automation, moreover is the flexible automation, thus the efficiency may enhance 3 ~ 7 times compared to the traditional engine bed.Because the computer has the memory and the memory prope rty, may the procedure which inputs remember and save, thenthe order which stipulated according to the procedure automat ic carries out, thus realization automation. The numerical co ntrol engine bed so long as replaces a procedure, may reali ze another work piece processing automation, thus causes the single unit and the small batch of production can automate, therefore is called has realized "flexible automation".2.1.3 processings components precision high, size dispersion d egree small, makes the assembly to be easy, no longer needs "to make repairs".2.1.4 may realize the multi- working procedures centralism, r educes the components in engine bed between frequent transpor ting.2.1.5 has auto-alarm, the automatic monitoring, automatic comp ensation and so on the many kinds of autonomy function, thu s may realize long time nobody to safeguard the processing.2.1.6 advantage which derives by above five.For example: Reduced worker's labor intensity, saved the labor force (a person to be possible to safeguard the multi - Taiwan engine bed), reduced the work clothes, reduced the new product trial manufacturing cycle and the production cycl e, might to the market demand make rapid reaction and so o n.Above these superiority are the predecessor cannot imagine, is an extremely significant breakthrough. In addition, the en gine bed numerical control carries out FMC (flexible manufact ure unit), FMS (flexible manufacture system) as well as CIMS (computer integration manufacture system) and so on the enter prise becoming an information based society transformation foundation. The numerical control technology already became the manufacturing industry automation the core technology and the foundation technology.2.2 great watches the transformation the necessityFrom on macroscopic looked that, the industry developed c ountry armed forces, the airplane weapon industry, in the en d of the 70's, at the beginning of the 80's started the l arge-scale application numerical control engine bed. Its essen ce is, uses the information technology to the traditional in dustry (including the armed forces, airplane weapon industry) carries on the technological transformations. Except that uses outside the numerical control engine bed, FMC, FMS in the m anufacture process, but also includes in the product developm ent carries out CAD, CAE, CAM, the hypothesized manufactureas well as carries out MIS in the production management (ma nagement information system), CIMS and so on. As well as in creases the information technology in its production product, including artificial intelligence and so on content. Because uses the information technology to the country foreign troops, the airplane weapon industry carries on the thorough transfor mation (to call it becoming an information based society), f inally causes them the product in the international military goods and in the goods for civilian use market the competit ive power greatly is the enhancement. But we in the informa tion technology transformation tradition industry aspect compar ed to the developed country to fall behind approximately for 20 years. Like in our country engine bed capacity, numerical control engine bed proportion (numerical control rate) to 199 5 only then 1.9%, but Japan has reached 20.8% in 1994, therefore every year has the massive mechanical and electrical products import. This also on from on macroscopic explained the engine bed numerical control transformation necessity. Tho rd, the numerical control transformation content and superiorl y lacks3.1 Transformation industry startingIn US, Japan and Germany and so on the developed countr y, their engine bed transforms took the new economical growt h profession, thrives abundantly, is occupying the golden age .As a result of the engine bed as well as the technical u nceasing progress, the engine bed transformation is "the eter nal" topic. Our country's engine bed transformation industry, also enters from the old profession to by the numerical c ontrol technology primarily new profession. In US, Japan, Ger many, have the broad market with the numerical control techn ological transformations engine bed and the production line, has formed the engine bed and the production line numerical control transformation new profession. In US, the engine be d transformation industry is called the engine bed regenerati on(Remanufacturing) industry. Is engaged in the regeneration ind ustry famous company to include: The Bertsche engineering fir m, the ayton engine bed company, Devlieg-Bullavd (are valuabl e) serves the group, the US equipment company and so on. T he American valuable company has set up the company in Chin a. In Japan, the engine bed transformation industry is calle d the engine bed to reequip (Retrofitting) industry. Is enga ged in the reequipment industry famous company to include: B ig indentation project group, hillock three mechanical companies, thousand substitute fields labor machine company, wild engineering firm, shore field engineering firm, mountain this engineering firm and so on. 3.2 Numerical control transformat ion contentThe engine bed and the production line numerical control transformation main content has following several points: First is extensively recovers the function, to the engine bed, the production line has the breakdown partially to carr y on the diagnosis and the restoration;Second is NC, the addend reveals the installment on the ordinary engine bed, or adds the numerical control system, transforms the NC engine bed, the CNC engine bed;Third is renovates, for increases the precision, the effi ciency and the automaticity, to the machinery, the electricit y partially carries on renovates, reassembles the processing to the machine part, extensively recovers the precision; Does not satisfy the production request to it the CNC system to carry on the renewal by newest CNC;Fourth is the technology renews or the technical innovati on, for enhances the performance or the scale, or in order to use the new craft, the new technology, carries on the b ig scale in the original foundation the technology to renew or the technical innovation, the great scope raises the leve l and the scale renewal transformation. The new electri cal system transforms after, how carries on the debugging as well as the determination reasonable approval standard, also is the technology preparatory work important link. The debugg ing work involves the machinery, the hydraulic pressure, the electricity, the control, and so on, therefore must carry onby the project person in charge, other personnel coordinate. The debugging step may conform to simplicity to numerous, fr om infancy to maturity, carries on from outside to in, afte r also may the partial overall situation, after first the s ubsystem the 3.3 The numerical control transformation superior ly lacks 3.3.1 reduced investment costs, the date of deliv ery are short With purchases the new engine bed to comp are, may save 60% ~ 80% expense generally, the transformatio n expense is low. Large-scale, the special engine bed especi ally is specially obvious. The common large-scale engine bed transforms, only spends the new engine bed purchase expense 1/3, the date of delivery is short. But some peculiar circu mstances, like the high speed main axle, the tray automatic switching unit manufacture and the installment too requires a lot of work, costs a great deal of money, often transforms the cost to enhance 2 ~ 3 times, with purchases the new engine bed to compare, only can economical invest about 50 %.3.3.2 machine capability stable are reliable, the structure i s limitedUses foundation and so on lathe bed, column all is heav y but the firm casting component, but is not that kind of welding component, after the transformation engine bed perform ance high, the quality is good, may take the new equipment continues to use many years. But receives the original mecha nism the limit, not suitably makes the unprecedented transfor mation. 3.3.3 familiar understood the equipment, is advantag eous for the operation serviceWhen purchases the new equipment, did not understand whether the new equipment can satisfy its processing request. Th e transformation then otherwise, may precisely calculate the engine bed the processing ability; Moreover, because many yea rs use, the operator already understood to the engine bed c haracteristic, uses and services the aspect to train the tim e in the operation short, effective is quick. The transforma tion engine bed as soon as installs, may realize the capaci ty load revolution. 3.3.4 may fully use the existing condi tionMay fully use the existing ground, does not need to lik e buys when the new equipment such to have reto construct the ground. 3.3.5 may use the newest control technology enhances the production equipment the automated level and the efficiency, improves the equipment quality and the scale, alters to the old engine bed now the horizontal engine bed. Fourth, numerical control system choiceWhen the numerical control system mainly has three kind of types, the transformation, should act according to the sp ecial details to carry on the choice.4.1 Step-by-steps the open system which the electrical ma chinery drivesThis system servo drive mainly is step-by-steps the elect rical machinery, the power step-by-steps the electrical machin ery, the battery solution pulse motor and so on. Entering s ends out which by the numerical control system for instructi on pulse, after the actuation electric circuit control and t he power enlargement, causes to step-by-step the electrical m achinery rotation, through gear vice- and ball bearing guide screw vice- actuation executive component. So long as the control command pulse quantity, the frequency as well as the circular telegram order, then may control the executive compo nent movement the displacement quantity, the speed and the h eading. This kind of system does not need the physical loca tion and the velocity feedback which obtains to the input e nd, therefore called it the open system, this system displac ement precision mainly decided in step-by-steps the electrical machinery angular displacement precision, transmission part and so on gear guide screw pitches the precision, therefore the system displacement precision is low.This system structure simple, debugging service convenient, work reliable, cost low, is easy to reequip successfully.4.2 The asynchronous motor or the direct current machine drive, diffraction grating survey feedback closed loop numer ical control system .This system and the open system difference is: Physical location feedback signal which by position detector set and so on the diffraction grating, induction synchromesh obtains, carries on the comparison as necessary with the given value, two interpolations enlargements and the transformation, the ac tuation implementing agency, by the speed which assigns turns towards the elimination deviation the direction movement, unti l assigns the position and the feedback physical location in terpolation is equal to the zero. The closed loop enters fo r the systemEnters for the system complex in the structure compared to the split-ring, the cost is also high, requests strictly to the environment room temperature. The design and the debu gging is all more difficult than the open system. But mayobtain compared to the split-ring enters for a system higher precision, quicker speed, actuation power bigger characteristic target. May act according to the product specification, decid ed whether uses this kind of system.4.3 The direct current servo electrical machinery drives, encoder feedback semi-closure link numerical control system .Half closed-loop system examination part installs in among passes in the moving parts, indirectly surveys the executive component the position. It only can compensate a system ring circuit interior part of part the error, therefore, its prec ision compared to closed-loop system precision low, but its structure and the debugging all compares the closed-loop syst em to be simple. In makes the angular displacement examinati on part and the speed examination part and the servo electr ical machinery time a whole then does not need to consider the position detector set installs the question.The current production numerical control system company fa ctory quite are many, overseas famous company like German SI EMENS Corporation,Japanese FANUC Corporation; Native corporation like China Mount Everest Corporation, Beijing astronautics eng ine bed numerical control system group company, Central China numerical control company and Shenyang upscale numerical contr ol country engineering research center.When choice numerical control system mainly is each kind of precision which the engine bed must achieve after the nu merical control transformation, actuates the electrical machine ry the power and user's request.Fifth in the numerical control transformation the mainmechanical part reequips the discussionA new numerical control engine bed, must achieve in the design that, Has the high static dynamic rigidity; Movement vice- between friction coefficient small, the transmission is ceaseless; The power is big; Is advantageous for the operati on and the service. When engine bed numerical control transf ormation should meet the above requirements as far as possib le. Cannot think the numerical control installment and the o rdinary engine bed connects in has met the numerical control engine bed requirements together, but also should carry on t he corresponding transformation to the major component to ena ble it to achieve the certain design request, can obtain th e anticipated transformation goal. 5.1 skids guide railSaid to the numerical control lathe that, the guide rail besides should have the conventional lathe guidance precision and the technology capability, but also must have good bears the friction, the attrition characteristic, and the reduction but sends the dead area because of the friction drag. At t he same time must have the enough rigidity, by reduces the guide rail to distort to processes the precision the influen ce, must have the reasonable guide rail protection and the lubrication.5.2 gearThe common engine bed gear mainly concentrates in the headstock and the gear box.In order to guarantee the transmission precision, on the numerical control engine bed uses the gear precision class i s all higher than the ordinary engine bed. Must be able to achieve the ceaseless transmissionin the structure, thus transforms time, the engine bed maingear must satisfy the numerical control engine bed the reque st, by guarantees the engine bed processing precision.5.3 skids the guide screw and the ball bearing guide screwThe guide screw transmission relates directly to the tran smission chain precision. The guide screw selects mainly is decided requests and drives the torque request in the job p recision. Is not used by job precision request Gao Shike skids the guide screw, but should inspect the original guide screw attrition situation, like the pitch error and the pitc h accumulative error as well as matches the nut gap. The o rdinary circumstances skid the guide screw to be supposed no t to be lower than 6 levels, the nut gap oversized then r eplaces the nut. Uses skids the guide screw relative ball b earing guide screw price to be low, but satisfies the pre cision high components processing with difficulty.The ball bearing guide screw rubs loses slightly, the ef ficiency is high, its transmission efficiency may above 90%; Precision high, the life is long; When start moment of forc e and movement the moment of force approaches, may reduce t he electrical machinery to start the moment of force. Theref ore may satisfiedly compare the high accuracy components proc essing request. 5.4 safe protectionThe effect must take the security as a premise. Transfor ms in the engine bed must take the corresponding measure ac cording to the actual situation, cuts noticeable. The ball b earing guide screw vice- is the precision part, when the wo rk must take strict precautions against the dust is speciall y the scrap and the hard sand grains enters the roller conveyer. On longitudinal guide screw also coca overall sheet i ron safety mask. The big carriage with skids two end surfac es which the guide rail contacts to have to seal, prevented absolutely the flinty granulated foreign matter enters the sl iding surface damage guide rail.Sixth, After the engine bed electrical system transformati on, to operates, the programmers inevitably brings the new r equest. Therefore ahead of time carries on new system knowle dge training to the operator and the programmers to be extr emely important, after otherwise will affect the transformatio n the engine bed rapid investment production. The training c ontent should include the new operation kneading board dispos ition, the function, the instruction meaning generally; New s ystem functional scope, application method and with old syste m difference; Maintenance maintenance request; Programming stan dard and automated programming and so on. The key point is makes, gets a good grasp of the operating manual and the p rogramming instruction booklet.the numerical control transforms se Transforms the scope according to each equipment differently, must beforehand desig n the connection partial transformations, if transforms comple tely, should design the electro-mechanical transformation conne ction, the operation kneading board control and the dispositi on, the interconnection partial contacts, the parameter measur ing point, services the position and so on, the request ope rates and services conveniently, reasonable, the line moves t owards, center the small junction smoothly few, the strong a nd the weak electrical noise is smallest, has the suitable allowance and so on. Partial transformation, but also needsto consider the new old system the performance match, the v oltage polarity and the size transformation, install the posi tion, the digital-analog conversion and so on, when the nece ssity must manufacture the transformation connection voluntaril y.veral examples1st, transforms the X53 milling machine with SIEMENS 810MIn 1998, the company invested 200,000 Yuan, with German Simens the 810M numerical control system, the 611A exchange servo drive system sds was the X53 milling machine carries on X, Y, the Z three axle numerical control transformation to a company's model; Retained the original main axle system and the cooling system; The transformation three axle has us ed the roller lead screw and the gear drive organization on the machinery. The entire transformation work including the m achine design, the electrical design, the PLC procedure estab lishment and the debugging, the engine bed overhaul, finally is the entire machine installment and the debugging. After t he milling machine transforms, processing effective stroke X/Y /The Z axis respectively is 88.0/270/28 billion mm; Maximum speed X/Y/The Z axis respectively is 5000/1500/800 mm/Min; Ma nual speed X/Y/The Z axis respectively is 3000/1000/500 mm/Mi n; The engine bed processing precision achieves ±0.001mm. The engine bed three coordinates linkage may complete each kind of complex curve or the curved surface processi ng.2nd, transforms the C6140 lathe with GSK980T and the exc hange servo drive system sds .In 2000, with Guangzhou numerical control plant production GSK980T numerical control system, the DA98 exchange servo uni t and 4 locations automatic tool rests to an electrical mac hinery branch factory C6140 lathe X, the Z two axes carries on the numerical control transformation; Retained the original main axle system and the cooling system; The transformation two axes have used the roller lead screw and with the ambu lacrum transmission system on the machinery. Entire transforma tion work including machine design, electrical design, engine bed overhaul and entire machine installment and debugging. Af ter the lathe transforms, processing effective stroke X/The Z axis respectively is 3.90/73 million mm; Maximum speed X/The Z axis respectively is 120.0/3 million mm/Min; The manual sp eed is 400mm/Min; Manual is fast is X/The Z axis respective ly is 120.0/3 million mm/Min; The engine bed smallest migrat ion unit is 0.001mm.3rd, transforms the X53 milling machine with SIEMENS 802SIn 2000, the company invests 120,000 Yuan, with German S imens the 802S numerical control system, step-by-steps the ac tuation system is the X53 milling machine carries on X, Y, the Z three axle numerical control transformation to company' s another model; Retained the original main axle system and the cooling system; The transformation three axle has used t he roller lead screw and the gear drive organization on the machinery. The entire transformation work including the machin e design, the electrical design, the engine bed overhaul, fi nally is the entire machine installment and the debugging. A fter the milling machine transforms, processing effective stro。
机械加工毕业论文中英文资料外文翻译文献
毕业论文中英文资料外文翻译文献附录附录1：英文原文Selection of optimum tool geometry and cutting conditionsusing a surface roughness prediction model for end milling Abstract Influence of tool geometry on the quality of surface produced is well known and hence any attempt to assess the performance of end milling should include the tool geometry. In the present work, experimental studies have been conducted to see the effect of tool geometry (radial rake angle and nose radius) and cutting conditions (cutting speed and feed rate) on the machining performance during end milling of medium carbon steel. The first and second order mathematical models, in terms of machining parameters, were developed for surface roughness prediction using response surface methodology (RSM) on the basis of experimental results. The model selected for optimization has been validated with the Chi square test. The significance of these parameters on surface roughness has been established with analysis of variance. An attempt has also been made to optimize the surface roughness prediction model using genetic algorithms (GA). The GA program gives minimum values of surface roughness and their respective optimal conditions.1 IntroductionEnd milling is one of the most commonly used metal removal operations in industry because of its ability to remove material faster giving reasonably good surface quality. It is used in a variety of manufacturing industries including aerospace and automotive sectors, where quality is an important factor in the production of slots, pockets, precision moulds and dies. Greater attention is given to dimensional accuracy and surface roughness of products by the industry these days. Moreover, surface finish influences mechanical properties such as fatigue behaviour, wear, corrosion, lubrication and electrical conductivity. Thus, measuring and characterizing surface finish can be considered for predicting machining performance.Surface finish resulting from turning operations has traditionally received considerable research attention, where as that of machining processes using multipoint cutters, requires attention by researchers. As these processes involve large number of parameters, it would bedifficult to correlate surface finish with other parameters just by conducting experiments. Modelling helps to understand this kind of process better. Though some amount of work has been carried out to develop surface finish prediction models in the past, the effect of tool geometry has received little attention. However, the radial rake angle has a major affect on the power consumption apart from tangential and radial forces. It also influences chip curling and modifies chip flow direction. In addition to this, researchers [1] have also observed that the nose radius plays a significant role in affecting the surface finish. Therefore the development of a good model should involve the radial rake angle and nose radius along with other relevant factors.Establishment of efficient machining parameters has been a problem that has confronted manufacturing industries for nearly a century, and is still the subject of many studies. Obtaining optimum machining parameters is of great concern in manufacturing industries, where the economy of machining operation plays a key role in the competitive market. In material removal processes, an improper selection of cutting conditions cause surfaces with high roughness and dimensional errors, and it is even possible that dynamic phenomena due to auto excited vibrations may set in [2]. In view of the significant role that the milling operation plays in today’s manufacturing world, there is a need to optimize the machining parameters for this operation. So, an effort has been made in this paper to see the influence of tool geometry(radial rake angle and nose radius) and cutting conditions(cutting speed and feed rate) on the surface finish produced during end milling of medium carbon steel. The experimental results of this work will be used to relate cutting speed, feed rate, radial rake angle and nose radius with the machining response i.e. surface roughness by modelling. The mathematical models thus developed are further utilized to find the optimum process parameters using genetic algorithms.2 ReviewProcess modelling and optimization are two important issues in manufacturing. The manufacturing processes are characterized by a multiplicity of dynamically interacting process variables. Surface finish has been an important factor of machining in predicting performance of any machining operation. In order to develop and optimize a surface roughness model, it is essential to understand the current status of work in this area.Davis et al. [3] have investigated the cutting performance of five end mills having various helix angles. Cutting tests were performed on aluminium alloy L 65 for three milling processes (face, slot and side), in which cutting force, surface roughness and concavity of a machined plane surface were measured. The central composite design was used to decide on the number of experiments to be conducted. The cutting performance of the end mills was assessed usingvariance analysis. The affects of spindle speed, depth of cut and feed rate on the cutting force and surface roughness were studied. The investigation showed that end mills with left hand helix angles are generally less cost effective than those with right hand helix angles. There is no significant difference between up milling and down milling with regard tothe cutting force, although the difference between them regarding the surface roughness was large. Bayoumi et al.[4] have studied the affect of the tool rotation angle, feed rate and cutting speed on the mechanistic process parameters (pressure, friction parameter) for end milling operation with three commercially available workpiece materials, 11 L 17 free machining steel, 62- 35-3 free machining brass and 2024 aluminium using a single fluted HSS milling cutter. It has been found that pressure and friction act on the chip – tool interface decrease with the increase of feed rate and with the decrease of the flow angle, while the cutting speed has a negligible effect on some of the material dependent parameters. Process parameters are summarized into empirical equations as functions of feed rate and tool rotation angle for each work material. However, researchers have not taken into account the effects of cutting conditions and tool geometry simultaneously; besides these studies have not considered the optimization of the cutting process.As end milling is a process which involves a large number f parameters, combined influence of the significant parameters an only be obtained by modelling. Mansour and Abdallaet al. [5] have developed a surface roughness model for the end milling of EN32M (a semi-free cutting carbon case hardening steel with improved merchantability). The mathematical model has been developed in terms of cutting speed, feed rate and axial depth of cut. The affect of these parameters on the surface roughness has been carried out using response surface methodology (RSM). A first order equation covering the speed range of 30–35 m/min and a second order equation covering the speed range of 24–38 m/min were developed under dry machining conditions. Alauddin et al. [6] developed a surface roughness model using RSM for the end milling of 190 BHN steel. First and second order models were constructed along with contour graphs for the selection of the proper combination of cutting speed and feed to increase the metal removal rate without sacrificing surface quality. Hasmi et al. [7] also used the RSM model for assessing the influence of the workpiece material on the surface roughness of the machined surfaces. The model was developed for milling operation by conducting experiments on steel specimens. The expression shows, the relationship between the surface roughness and the various parameters; namely, the cutting speed, feed and depth of cut. The above models have not considered the affect of tool geometry on surface roughness.Since the turn of the century quite a large number of attempts have been made to find optimum values of machining parameters. Uses of many methods have been reported in the literature to solve optimization problems for machining parameters. Jain and Jain [8] have usedneural networks for modeling and optimizing the machining conditions. The results have been validated by comparing the optimized machining conditions obtained using genetic algorithms. Suresh et al. [9] have developed a surface roughness prediction model for turning mild steel using a response surface methodology to produce the factor affects of the individual process parameters. They have also optimized the turning process using the surface roughness prediction model as the objective function. Considering the above, an attempt has been made in this work to develop a surface roughness model with tool geometry and cutting conditions on the basis of experimental results and then optimize it for the selection of these parameters within the given constraints in the end milling operation.3 MethodologyIn this work, mathematical models have been developed using experimental results with the help of response surface methodolog y. The purpose of developing mathematical models relating the machining responses and their factors is to facilitate the optimization of the machining process. This mathematical model has been used as an objective function and the optimization was carried out with the help of genetic algorithms.3.1 Mathematical formulationResponse surface methodology(RSM) is a combination of mathematical and statistical techniques useful for modelling and analyzing the problems in which several independent variables influence a dependent variable or response. The mathematical models commonly used are represented by:where Y is the machining response, ϕ is the response function and S, f , α, r are milling variables and ∈is the error which is normally distributed about the observed response Y with zero mean.The relationship between surface roughness and other independent variables can be represented as follows，where C is a constant and a, b, c and d are exponents.To facilitate the determination of constants and exponents, this mathematical model will have to be linearized by performing a logarithmic transformation as follows:The constants and exponents C, a, b, c and d can be determined by the method of least squares. The first order linear model, developed from the above functional relationship using least squares method, can be represented as follows:where Y1 is the estimated response based on the first-order equation, Y is the measured surface roughness on a logarithmic scale, x0 = 1 (dummy variable), x1, x2, x3 and x4 are logarithmic transformations of cutting speed, feed rate, radial rake angle and nose radiusrespectively, ∈is the experimental error and b values are the estimates of corresponding parameters.The general second order polynomial response is as given below:where Y2 is the estimated response based on the second order equation. The parameters, i.e. b0, b1, b2, b3, b4, b12, b23, b14, etc. are to be estimated by the method of least squares. Validity of the selected model used for optimizing the process parameters has been tested with the help of statistical tests, such as F-test, chi square test, etc. [10].3.2 Optimization using genetic algorithmsMost of the researchers have used traditional optimization techniques for solving machining problems. The traditional methods of optimization and search do not fare well over a broad spectrum of problem domains. Traditional techniques are not efficient when the practical search space is too large. These algorithms are not robust. They are inclined to obtain a local optimal solution. Numerous constraints and number of passes make the machining optimization problem more complicated. So, it was decided to employ genetic algorithms as an optimization technique. GA come under the class of non-traditional search and optimization techniques. GA are different from traditional optimization techniques in the following ways:1.GA work with a coding of the parameter set, not the parameter themselves.2.GA search from a population of points and not a single point.3.GA use information of fitness function, not derivatives or other auxiliary knowledge.4.GA use probabilistic transition rules not deterministic rules.5.It is very likely that the expected GA solution will be the global solution.Genetic algorithms (GA) form a class of adaptive heuristics based on principles derived from the dynamics of natural population genetics. The searching process simulates the natural evaluation of biological creatures and turns out to be an intelligent exploitation of a random search. The mechanics of a GA is simple, involving copying of binary strings. Simplicity of operation and computational efficiency are the two main attractions of the genetic algorithmic approach. The computations are carried out in three stages to get a result in one generation or iteration. The three stages are reproduction, crossover and mutation.In order to use GA to solve any problem, the variable is typically encoded into a string (binary coding) or chromosome structure which represents a possible solution to the given problem. GA begin with a population of strings (individuals) created at random. The fitness of each individual string is evaluated with respect to the given objective function. Then this initial population is operated on by three main operators – reproduction cross over and mutation– to create, hopefully, a better population. Highly fit individuals or solutions are given theopportunity to reproduce by exchanging pieces of their genetic information, in the crossover procedure, with other highly fit individuals. This produces new “offspring” solutions, which share some characteristics taken from both the parents. Mutation is often applied after crossover by altering some genes (i.e. bits) in the offspring. The offspring can either replace the whole population (generational approach) or replace less fit individuals (steady state approach). This new population is further evaluated and tested for some termination criteria. The reproduction-cross over mutation- evaluation cycle is repeated until the termination criteria are met.4 Experimental detailsFor developing models on the basis of experimental data, careful planning of experimentation is essential. The factors considered for experimentation and analysis were cutting speed, feed rate, radial rake angle and nose radius.4.1 Experimental designThe design of experimentation has a major affect on the number of experiments needed. Therefore it is essential to have a well designed set of experiments. The range of values of each factor was set at three different levels, namely low, medium and high as shown in Table 1. Based on this, a total number of 81 experiments (full factorial design), each having a combination of different levels of factors, as shown in Table 2, were carried out.The variables were coded by taking into account the capacity and limiting cutting conditions of the milling machine. The coded values of variables, to be used in Eqs. 3 and 4, were obtained from the following transforming equations:where x1 is the coded value of cutting speed (S), x2 is the coded value of the feed rate ( f ), x3 is the coded value of radial rake angle(α) and x4 is the coded value of nose radius (r).4.2 ExperimentationA high precision ‘Rambaudi Rammatic 500’ CNC milling machine, with a vertical milling head, was used for experimentation. The control system is a CNC FIDIA-12 compact. The cutting tools, used for the experimentation, were solid coated carbide end mill cutters of different radial rake angles and nose radii (WIDIA: DIA20 X FL38 X OAL 102 MM). The tools are coated with TiAlN coating. The hardness, density and transverse rupture strength are 1570 HV 30, 14.5 gm/cm3 and 3800 N/mm2 respectively.AISI 1045 steel specimens of 100×75 mm and 20 mm thickness were used in the present study. All the specimens were annealed, by holding them at 850 ◦C for one hour and then cooling them in a furnace. The chemical analysis of specimens is presented in Table 3. Thehardness of the workpiece material is 170 BHN. All the experiments were carried out at a constant axial depth of cut of 20 mm and a radial depth of cut of 1 mm. The surface roughness (response) was measured with Talysurf-6 at a 0.8 mm cut-off value. An average of four measurements was used as a response value.5 Results and discussionThe influences of cutting speed, feed rate, radial rake angle and nose radius have been assessed by conducting experiments. The variation of machining response with respect to the variables was shown graphically in Fig. 1. It is seen from these figures that of the four dependent parameters, radial rake angle has definite influence on the roughness of the surface machined using an end mill cutter. It is felt that the prominent influence of radial rake angle on the surface generation could be due to the fact that any change in the radial rake angle changes the sharpness of the cutting edge on the periphery, i.e changes the contact length between the chip and workpiece surface. Also it is evident from the plots that as the radial rake angle changes from 4◦to 16◦, the surface roughness decreases and then increases. Therefore, it may be concluded here that the radial rake angle in the range of 4◦to 10◦would give a better surface finish. Figure 1 also shows that the surface roughness decreases first and then increases with the increase in the nose radius. This shows that there is a scope for finding the optimum value of the radial rake angle and nose radius for obtaining the best possible quality of the surface. It was also found that the surface roughness decreases with an increase in cutting speed and increases as feed rate increases. It could also be observed that the surface roughness was a minimum at the 250 m/min speed, 200 mm/min feed rate, 10◦radial rake angle and 0.8 mm nose radius. In order to understand the process better, the experimental results can be used to develop mathematical models using RSM. In this work, a commercially available mathematical software package (MATLAB) was used for the computation of the regression of constants and exponents.5.1 The roughness modelUsing experimental results, empirical equations have been obtained to estimate surface roughness with the significant parameters considered for the experimentation i.e. cutting speed, feed rate, radial rake angle and nose radius. The first order model obtained from the above functional relationship using the RSM method is as follows:The transformed equation of surface roughness prediction is as follows:Equation 10 is derived from Eq. 9 by substituting the coded values of x1, x2, x3 and x4 in termsof ln s, ln f , lnαand ln r. The analysis of the variance (ANOV A) and the F-ratio test have been performed to justify the accuracy of the fit for the mathematical model. Since the calculated values of the F-ratio are less than the standard values of the F-ratio for surface roughness as shown in Table 4, the model is adequate at 99% confidence level to represent the relationship between the machining response and the considered machining parameters of the end milling process.The multiple regression coefficient of the first order model was found to be 0.5839. This shows that the first order model can explain the variation in surface roughness to the extent of 58.39%. As the first order model has low predictability, the second order model has been developed to see whether it can represent better or not.The second order surface roughness model thus developed is as given below:where Y2 is the estimated response of the surface roughness on a logarithmic scale, x1, x2, x3 and x4 are the logarithmic transformation of speed, feed, radial rake angle and nose radius. The data of analysis of variance for the second order surface roughness model is shown in Table 5.Since F cal is greater than F0.01, there is a definite relationship between the response variable and independent variable at 99% confidence level. The multiple regression coefficient of the second order model was found to be 0.9596. On the basis of the multiple regression coefficient (R2), it can be concluded that the second order model was adequate to represent this process. Hence the second order model was considered as an objective function for optimization using genetic algorithms. This second order model was also validated using the chi square test. The calculated chi square value of the model was 0.1493 and them tabulated value at χ2 0.005 is 52.34, as shown in Table 6, which indicates that 99.5% of the variability in surface roughness was explained by this model.Using the second order model, the surface roughness of the components produced by end milling can be estimated with reasonable accuracy. This model would be optimized using genetic algorithms (GA).5.2 The optimization of end millingOptimization of machining parameters not only increases the utility for machining economics, but also the product quality toa great extent. In this context an effort has been made to estimate the optimum tool geometry and machining conditions to produce the best possible surface quality within the constraints.The constrained optimization problem is stated as follows: Minimize Ra using the model given here:where xil and xiu are the upper and lower bounds of process variables xi and x1, x2, x3, x4 are logarithmic transformation of cutting speed, feed, radial rake angle and nose radius.The GA code was developed using MATLAB. This approach makes a binary coding system to represent the variables cutting speed (S), feed rate ( f ), radial rake angle (α) and nose radius (r), i.e. each of these variables is represented by a ten bit binary equivalent, limiting the total string length to 40. It is known as a chromosome. The variables are represented as genes (substrings) in the chromosome. The randomly generated 20 such chromosomes (population size is 20), fulfilling the constraints on the variables, are taken in each generation. The first generation is called the initial population. Once the coding of the variables has been done, then the actual decoded values for the variables are estimated using the following formula: where xi is the actual decoded value of the cutting speed, feed rate, radial rake angle and nose radius, x(L) i is the lower limit and x(U) i is the upper limit and li is the substring length, which is equal to ten in this case.Using the present generation of 20 chromosomes, fitness values are calculated by the following transformation:where f(x) is the fitness function and Ra is the objective function.Out of these 20 fitness values, four are chosen using the roulette-wheel selection scheme. The chromosomes corresponding to these four fitness values are taken as parents. Then the crossover and mutation reproduction methods are applied to generate 20 new chromosomes for the next generation. This processof generating the new population from the old population is called one generation. Many such generations are run till the maximum number of generations is met or the average of four selected fitness values in each generation becomes steady. This ensures that the optimization of all the variables (cutting speed, feed rate, radial rake angle and nose radius) is carried out simultaneously. The final statistics are displayed at the end of all iterations. In order to optimize the present problem using GA, the following parameters have been selected to obtain the best possible solution with the least computational effort: Table 7 shows some of the minimum values of the surface roughness predicted by the GA program with respect to input machining ranges, and Table 8 shows the optimum machining conditions for the corresponding minimum values of the surface roughness shown in Table 7. The MRR given in Table 8 was calculated bywhere f is the table feed (mm/min), aa is the axial depth of cut (20 mm) and ar is the radial depth of cut (1 mm).It can be concluded from the optimization results of the GA program that it is possible toselect a combination of cutting speed, feed rate, radial rake angle and nose radius for achieving the best possible surface finish giving a reasonably good material removal rate. This GA program provides optimum machining conditions for the corresponding given minimum values of the surface roughness. The application of the genetic algorithmic approach to obtain optimal machining conditions will be quite useful at the computer aided process planning (CAPP) stage in the production of high quality goods with tight tolerances by a variety of machining operations, and in the adaptive control of automated machine tools. With the known boundaries of surface roughness and machining conditions, machining could be performed with a relatively high rate of success with the selected machining conditions.6 ConclusionsThe investigations of this study indicate that the parameters cutting speed, feed, radial rake angle and nose radius are the primary actors influencing the surface roughness of medium carbon steel uring end milling. The approach presented in this paper provides n impetus to develop analytical models, based on experimental results for obtaining a surface roughness model using the response surface methodology. By incorporating the cutter geometry in the model, the validity of the model has been enhanced. The optimization of this model using genetic algorithms has resulted in a fairly useful method of obtaining machining parameters in order to obtain the best possible surface quality.中文翻译选择最佳工具，几何形状和切削条件利用表面粗糙度预测模型端铣摘要：刀具几何形状对工件表面质量产生的影响是人所共知的，因此，任何成型面端铣设计应包括刀具的几何形状。
机械类英文文献+翻译
机器产业出书社2004年3月第1版20.9 MACHINABILITYThe machinability of a material usually defined in terms of four factors:1、Surface finish and integrity of the machined part;2、Tool life obtained;3、Force and power requirements;4、Chip control.Thus, good machinability good surface finish and integrity, long tool life, and low force And power requirements. As for chip control, long and thin (stringy) cured chips, if not broken up, can severely interfere with the cutting operation by becoming entangled in the cutting zone.Because of the complex nature of cutting operations, it is difficult to establish relationships that quantitatively define the machinability of a material. In manufacturing plants, tool life and surface roughness are generally considered to be the most important factors in machinability. Although not used much any more, approximate machinability ratings are available in the example below. Machinability Of SteelsBecause steels are among the most important engineering materials (as noted in Chapter 5), their machinability has been studied extensively. The machinability of steels has been mainly improved by adding lead and sulfur to obtain so-called free-machining steels.Resulfurized and Rephosphorized steels. Sulfur in steels forms manganese sulfide inclusions (second-phase particles), which act as stress raisers in the primary shear zone. As a result, the chips produced break up easily and are small; this improves machinability. The size, shape, distribution, and concentration of these inclusions significantly influence machinability. Elements such as tellurium and selenium, which are both chemically similar to sulfur, act as inclusion modifiers in resulfurized steels.Phosphorus in steels has two major effects. It strengthens the ferrite, causingincreased hardness. Harder steels result in better chip formation and surface finish. Note that soft steels can be difficult to machine, with built-up edge formation and poor surface finish. The second effect is that increased hardness causes the formation of short chips instead of continuous stringy ones, thereby improving machinability.Leaded Steels. A high percentage of lead in steels solidifies at the tip of manganese sulfide inclusions. In non-resulfurized grades of steel, lead takes the form of dispersed fine particles. Lead is insoluble in iron, copper, and alumin um and their alloys. Because of its low shear strength, therefore, lead acts as a solid lubricant (Section 32.11) and is smeared over the tool-chip interface du ring cutting. This behavior has been verified by the presence of high concentra tions of lead on the tool-side face of chips when machining leaded steels.When the temperature is sufficiently high-for instance, at high cutting spee ds and feeds (Section 20.6)—the lead melts directly in front of the tool, acting as a liquid lubricant. In addition to this effect, lead lowers the shear stress in the primary shear zone, reducing cutting forces and power consumption. Lead can be used in every grade of steel, such as 10xx, 11xx, 12xx, 41xx, etc. Le aded steels are identified by the letter L between the second and third numeral s (for example, 10L45). (Note that in stainless steels, similar use of the letter L means “low carbon,”a condition that improves their corrosion resistance.)However, because lead is a well-known toxin and a pollutant, there are se rious environmental concerns about its use in steels (estimated at 4500 tons of lead consumption every year in the production of steels). Consequently, there is a continuing trend toward eliminating the use of lead in steels (lead-free ste els). Bismuth and tin are now being investigated as possible substitutes for lea d in steels.Calcium-Deoxidized Steels. An important development is calcium-deoxidize d steels, in which oxide flakes of calcium silicates (CaSo) are formed. These f lakes, in turn, reduce the strength of the secondary shear zone, decreasing tool-chip interface and wear. Temperature is correspondingly reduced. Consequently, these steels produce less crater wear, especially at high cutting speeds.Stainless Steels. Austenitic (300 series) steels are generally difficult to mac hine. Chatter can be s problem, necessitating machine tools with high stiffness. However, ferritic stainless steels (also 300 series) have good machinability. Martensitic (400 series) steels are abrasive, tend to form a built-up edge, and req uire tool materials with high hot hardness and crater-wear resistance. Precipitati on-hardening stainless steels are strong and abrasive, requiring hard and abrasio n-resistant tool materials.The Effects of Other Elements in Steels on Machinability. The presence of aluminum and silicon in steels is always harmful because these elements com bine with oxygen to form aluminum oxide and silicates, which are hard and a brasive. These compounds increase tool wear and reduce machinability. It is es sential to produce and use clean steels.Carbon and manganese have various effects on the machinability of steels, depending on their composition. Plain low-carbon steels (less than 0.15% C) c an produce poor surface finish by forming a built-up edge. Cast steels are mor e abrasive, although their machinability is similar to that of wrought steels. To ol and die steels are very difficult to machine and usually require annealing pr ior to machining. Machinability of most steels is improved by cold working, w hich hardens the material and reduces the tendency for built-up edge formation.Other alloying elements, such as nickel, chromium, molybdenum, and vana dium, which improve the properties of steels, generally reduce machinability. T he effect of boron is negligible. Gaseous elements such as hydrogen and nitrog en can have particularly detrimental effects on the properties of steel. Oxygen has been shown to have a strong effect on the aspect ratio of the manganese sulfide inclusions; the higher the oxygen content, the lower the aspect ratio an d the higher the machinability.In selecting various elements to improve machinability, we should consider the possible detrimental effects of these elements on the properties and strengt h of the machined part in service. At elevated temperatures, for example, lead causes embrittlement of steels (liquid-metal embrittlement, hot shortness; see Se ction ), although at room temperature it has no effect on mechanical properties.Sulfur can severely reduce the hot workability of steels, because of the fo rmation of iron sulfide, unless sufficient manganese is present to prevent such formation. At room temperature, the mechanical properties of resulfurized steelsdepend on the orientation of the deformed manganese sulfide inclusions (aniso tropy). Rephosphorized steels are significantly less ductile, and are produced so lely to improve machinability.Machinability of Various Other MetalsAluminum is generally very easy to machine, although the softer grades te nd to form a built-up edge, resulting in poor surface finish. High cutting speed s, high rake angles, and high relief angles are recommended. Wrought aluminu m alloys with high silicon content and cast aluminum alloys may be abrasive; they require harder tool materials. Dimensional tolerance control may be a pro blem in machining aluminum, since it has a high thermal coefficient of expans ion and a relatively low elastic modulus.Beryllium is similar to cast irons. Because it is more abrasive and toxic, t hough, it requires machining in a controlled environment.Cast gray irons are generally machinable but are. Free carbides in castings reduce their machinability and cause tool chipping or fracture, necessitating to ols with high toughness. Nodular and malleable irons are machinable with hard tool materials.Cobalt-based alloys are abrasive and highly work-hardening. They require sharp, abrasion-resistant tool materials and low feeds and speeds.Wrought copper can be difficult to machine because of built-up edge form ation, although cast copper alloys are easy to machine. Brasses are easy to ma chine, especially with the addition pf lead (leaded free-machining brass). Bronz es are more difficult to machine than brass.Magnesium is very easy to machine, with good surface finish and prolong ed tool life. However care should be exercised because of its high rate of oxi dation and the danger of fire (the element is pyrophoric).Molybdenum is ductile and work-hardening, so it can produce poor surfac e finish. Sharp tools are necessary.Nickel-based alloys are work-hardening, abrasive, and strong at high tempe ratures. Their machinability is similar to that of stainless steels.Tantalum is very work-hardening, ductile, and soft. It produces a poor surf ace finish; tool wear is high.Titanium and its alloys have poor thermal conductivity (indeed, the lowest of all metals), causing significant temperature rise and built-up edge; they can be difficult to machine.Tungsten is brittle, strong, and very abrasive, so its machinability is low, although it greatly improves at elevated temperatures.Zirconium has good machinability. It requires a coolant-type cutting fluid, however, because of the explosion and fire.Machinability of Various MaterialsGraphite is abrasive; it requires hard, abrasion-resistant, sharp tools.Thermoplastics generally have low thermal conductivity, low elastic modul us, and low softening temperature. Consequently, machining them requires tools with positive rake angles (to reduce cutting forces), large relief angles, small depths of cut and feed, relatively high speeds, and proper support of the work piece. Tools should be sharp.External cooling of the cutting zone may be necessary to keep the chips f rom becoming “gummy”and sticking to the tools. Cooling can usually be achi eved with a jet of air, vapor mist, or water-soluble oils. Residual stresses may develop during machining. To relieve these stresses, machined parts can be an nealed for a period of time at temperatures ranging from to ( to ), and then cooled slowly and uniformly to room temperature.Thermosetting plastics are brittle and sensitive to thermal gradients during cutting. Their machinability is generally similar to that of thermoplastics.Because of the fibers present, reinforced plastics are very abrasive and are difficult to machine. Fiber tearing, pulling, and edge delamination are significa nt problems; they can lead to severe reduction in the load-carrying capacity of the component. Furthermore, machining of these materials requires careful rem oval of machining debris to avoid contact with and inhaling of the fibers.The machinability of ceramics has improved steadily with the development of nanoceramics (Section ) and with the selection of appropriate processing pa rameters, such as ductile-regime cutting (Section 22.4.2).Metal-matrix and ceramic-matrix composites can be difficult to machine, d epending on the properties of the individual components, i.e., reinforcing or wh iskers, as well as the matrix material.Thermally Assisted MachiningMetals and alloys that are difficult to machine at room temperature can be machined more easily at elevated temperatures. In thermally assisted machinin g (hot machining), the source of heat—a torch, induction coil, high-energy bea m (such as laser or electron beam), or plasma arc—is forces, (b) increased too l life, (c) use of inexpensive cutting-tool materials, (d) higher material-removal rates, and (e) reduced tendency for vibration and chatter.It may be difficult to heat and maintain a uniform temperature distribution within the workpiece. Also, the original microstructure of the workpiece may be adversely affected by elevated temperatures. Most applications of hot machi ning are in the turning of high-strength metals and alloys, although experiment s are in progress to machine ceramics such as silicon nitride.SUMMARYMachinability is usually defined in terms of surface finish, tool life, force and power requirements, and chip control. Machinability of materials depends n ot only on their intrinsic properties and microstructure, but also on proper sele ction and control of process variables.20.9 可机加工性一种质料的可机加工性通常以四种因素的方法界说：1、分的外貌光洁性和外貌完整性。
机械外文翻译中英文-机床【范本模板】
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 workpiece. Basically, in metal cutting, a sharpened wedge-shaped tool removes a rather narrow strip of metal from the surface of a ductile workpiece in the form of a severely deformed chip. The chip is a waste product that is considerably shorter than the workpiece from which it came but with a corresponding increase in thickness of the uncut chip. The geometrical shape of workpiece depends on the shape of the tool and its path during the machining operation。
机床术语中英文对照表
Honing machines
搪磨机
Hydraulic components
液压元件
Hydraulic power tools
液压工具
Hydraulic power units
液压动力元件
Hydraulic rotary cylinders
液压回转缸
Jigs
钻模
Lapping machines
电脑数控磨床
CNC lathes
电脑数控车床
CNC machine tool fittings
电脑数控机床配件
CNC milling machines
电脑数控铣床
CNC shearing machines
电脑数控剪切机
CNC toolings
CNC刀杆
CNC wire-cutting machines
螺纹磨床
Grinders,tools & cutters
工具磨床
Grinders,ultrasonic
超声波打磨机
Grinding machines
磨床
Grinding machines,centerless
无心磨床
Grinding machines,cylindrical
外圆磨床
Grinding machines,universal
电脑数控镗床
CNC drilling machines
电脑数控钻床
CNC EDM wire-cutting machines
电脑数控电火花线切削机
CNC electric discharge machines
电脑数控电火花机
CNC engraving machines
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中英文资料翻译原文：AUTOMATING THE CONTROL OF MODERN EQUIPMENT FOR STRAIGHTENING FLAT-ROLLED PRODUCTS The company Severstal’ completed the successful introduction of new in-line plate-straightening machines (PSMs) on its 2800 and 5000 mills in August 2003 [1, 2, 3]. The main design features of the machines are as follows:●each machine is equipped with hydraulic hold-down mechanisms (toimprove the dynamics and accuracy of the machine adjustments and more reliably maintain a constant gap);●the machines have mechanisms to individually adjust each work roller with the aid ofhydraulic cylinders (this broadens the range of straightening regimes that can be realized by providing a measure of control over the change in the curvature of the plate);●each work roller is provided with its own adjustable drive (to eliminate rigidkinematic constraints between the spindles);●the system of rollers of the PSM is enclosed in cassettes (to facilitate repairs andreduce roller replacement costs);●the PSM has a system that can be used to adjust the machine from a nine-rollerstraightening scheme to a five-●roller scheme in which the distance between the rollers is doubled (this is done towiden the range of plate thick-nesses that the machine can accomodate).Thus, the new straightening machine is a sophisticated multi-function system of mechanisms that includes a wide range of hydraulically and electrically driven components controlled by digital and analog signals. The entire complex of PSM mechanisms can be divided into two functional groups: the main group, which includes the mechanisms that partici-pate directly in the straightening operation (the hold-down mechanisms, the mechanisms that individually adjust the rollers,the mechanisms that adjust the components for different straightening regimes, the mechanism that moves the top roller of the feeder, and the main drive); the auxiliary group (which includes the cassette replacement mechanism, thespindle-lock-ing mechanism, and the equipment that cools the system of rollers). Although the PSM has a large number of mechanisms,the use of modern hydraulic and electric drives has made it possible to almost completely automate the main and auxiliary operations performed on the PSM and the units that operate with it.Described below are the features and the automatic control systems for the most important mechanisms of the plate-straightening machine.The operating regimes of those mechanisms are also discussed.The hydraulic hold-down mechanisms (HHMs) of the sheet-straightening machine function in two main regimes:the adjustment regime;the regime in which the specified positions are maintained.There are certain requirements for the control system and certain efficiency criteria for each regime.In the adjustment regime, the control system for the hydraulic hold-down mechanisms must do the following:●synchronize the movements of the hydraulic cylinders and keep the angulardeeflection within prescribed limits;●maximize speed in adjusting the machine for a new plate size;●maintain a high degree of accuracy in positioning the mechanisms;Fig. 1. Block diagram of the control system of the hydraulic cylinder.The control system has the following requirements when operating in the maintenance regime:●stabilize the coordinates of the top cassette and the top roller of the feeder with a highdegree of accuracy;●minimize the time needed to return the equipment to the prescribed coordinates whendeviations occur (such as due to the force exerted by a plate being straightened).Need for synchronization. Experience in operating the plate-straightening machine in plate shop No. 3 at Severstal’ has shown that the most problematic factor in adjusting the machine is the nonuniformity of the forces applied to the hydraulic cylinders. This nonuniformity is due to the asymmetric distribution of the masses of the moving parts of the PSM (in particular, the effect of the weight of the spindle assembly). Displacement of the “hydraulic zero point”relative to the “electrical zero point” in the servo valves is also a contributing factor.The latter reason is more significant, the smaller the volume of the hydraulic cylinder.Thus, the HHM of the top roller of the feeder is the most sensitive to drift of the zero point.There are also other factors that affect the dynamism,simultaneousness,and synchronism of the operation of the hold-down mechanisms:●differentiation of the frictional forces on parts of the hydraulic cylinders due todifferent combinations of deviations in the dimensions of the mated parts, despite the narrow tolerances;●differences in the “springing” characteristics and the indices characterizing the inertiaof the hydraulic supply channels (due to differences in the lengths of the pipes leading from the servo valves to the hydraulic cylinders).Thus, since the PSM is not equipped with devices to mechanically synchronize the operation of the cylinders, the ransmission of signals of the same amplitude to the inputs of the servo valves inevitably results in a speed difference that can seriously damage the mechanisms.To minimize and eliminate the effects of the above-mentioned factors, we developed an algorithm for electrical synchronization of the hold-down mechanisms.The HHM of the top cassette, composed of four hold-down cylinders and four balancing cylinders, is designed to ensuremobile adjustment of the machine to set the required size of straightening gap (in accordance with the thickness of the plate) andmaintain that gap with a specified accuracy in the presence .and absence of a load on the housings from the straightening force.The hydraulic system of the hold-down mechanism is designed in such a way that only one chamber of the hydraulic cylinders is used as the working chamber.The second chamber is always connected to the discharge channel.The top cassette is lowered when the balancing forces are overcome by the hold-down cylinders.The cassette is raised only by the action of the balancing cylinders.This arrangement has made it possible to eliminate gaps in the positioning of the equipment.The HHM of the top roller of the feeder consists of two hydraulic cylinders. Hydraulic fluid is fed into the plunger chamber when the roller is to be lowered and is fed into the rod chamber when it is to be raised.Control Principles. Individual circuits have been provided (Fig.1) to control the hydraulic cylinders of the hold-down mechanisms.The control signal (Xctl) sent to the input of theservo valve is formed by a proportional-integral (PI) controller (to improve the sensitivity of the system, we chose to use valves with “zero” overlap).The signal sent to the input of the controller (the error signal Xerr) is formed as the difference between the control-point signal for position (Xcpt) and the feedback signal (Xf.b).The latter signal is received from the linear displacement gage (G) of the given hydraulic cylinder.The gages of the HHM for the top cassette are built into the balancing hydraulic cylinders (HCs).The cylinders are installed in such a way that their movements can be considered to be equal to the displacements of the corresponding cylinder rods, with allowance for certain coefficients.The gages in the HHM for the top roller of the feeder are incorporated directly into the hold-down cylinders.The integral part of the controller is activated only during the final adjustment stage and during stabilization of the prescribed coordinate.When the displacements exceed a certain threshold value, the functions of the PI controller are taken over by a proportional (P) controller with the transfer function W(s) = k.Thus, Xctl(t) = kXerr(t).When there are significant differences between the displacements of the working rollers,the difference (error)between the control point and the feedback signal from the linear displacement gage reaches values great enough so that the output signal which controls the operation of the servo valve reaches the saturation zone.In this case, further regulation of the displacement rate and,thus synchronization of the movements of the cylinders becomes impossible as long as the error exceeds the value at which Xctl is greater than the boundary value for the saturation zone (Xsat).The limiting error–the largest error for which Xctldoes not reach saturation–is inversely proportional to the gain of the controller k: Xerr< Xsat/ k. Solving the given problem by decreasing k leads to a loss of speed in the adjustment of the PSM and a decrease in control accuracy during the straightening operation.Thus, to keep the control signal from reaching the saturation zone when there are substantial displacements, the system was designed so that the input of the controller is fed not the actual required value (Xrq) but an increment (∆X) of a magnitude such that the condition k∆X < Xsat is satisfied.The control point is increased by the amount ∆X after the position of the cylinder has been changed by the amount corresponding to the increment having the largest lag relative to the cylinder’s direction of motion. The adjustment of the control point is continued until the difference between the required value and the actual position of the mechanism becomes less than the increment:Xrq –Xf.b < ∆X.Then the input of the controller is fed the value Xcpt, which is equal to the required adjustment: Xcpt= Xrq.The adjustment is thus completed.Use of the principle of a stepped increase in the control point makes it possible synchronize the movements of the cylinders and set the control point with a high degree of accuracy for almost any ideal repetition factor.Mechanisms for Individual Adjustment of the Working Rollers.The plate-straightening machine is designed so that each working roller can be moved vertically, which is done by means of a hydraulic cylinder acting in concert with a V-belt drive.The cylinders are supplied with power from servo valves operated with proportional control.A linear displacement gage is built into each cylinder to obtain a feedback signal on the position of the roller.Since these gages are actually transmitinginformation on the position of the cylinder rods rather than the working rollers themselves, the following conversion is performed to obtain the rollers’ coordinates:Xrol= kredXf.b,where kred is the gear ratio of the drive;Xf.b is the position of the cylinder rod measured by the linear displacement transducers.Thus, a position feedback circuit is provided to control the position of each working roller. Figure 1 presents a diagram of one of the circuits.The control signals are generated by means of the PI controllere, which has made it possible to achieve a high degree of accuracy in adjusting the system without sacrificing speed.The individual drive of the rollers. The above-described design is based on the use of individual ac drives with motors of different powers fed from frequency converters. Each individual drive offers the following advantages over a group drive:●greater reliability thanks to the absence of additional loads on the components of themechanisms due to differences between the linear velocities of the working rollers and the speed of the plate;●the possibility that the machine could continue to operate if one or even severaldrives malfunction;in this case,the corresponding rollers would be removed from the straightening zone;●the possibility that the linear velocities of the rollers could be individually correctedin accordance with the actual speed of the plate;such a correction could be made either asa preliminary measure (on the basis of measured and calculated values) or during thestraightening operation (on the basis of the data obtained from the frequency converters, which employ artificial intelligence).The main drive of the straightening machine rotates nine straightening rollers and twohousing rollers.This drive must be highly reliable in operation, since the fact that the PSM is installed in the mill line means that sizable production losses can be incurred if the drive fails to work properly even for a short period of time.The requirements that must be satisfied by the drive are determined by the operational and design features of the machine as a whole:●the plate being straightened must create a rigid kinematic coupling between thestraightening rollers, the rollers of the housing, and the adjacent sections of the roller conveyors;●the plate should undergo elongation during the straightening operation as a result ofplastic deformation, with the increments in length being different on each working roller due to the differentiation of the bending radii;this situation leads to a nonuniform increase in the speed of the plate as it moves toward the end of the PSM;●it must be possible to use working rollers of different diameters (this being done, forexample, due to nonuniform wear or regrinding);●the loads on the rollers should be differentiated in accordance with the chosenstraightening regime;●reverse straightening should be possible.In light of the above factors and the actual operating regimes of the plate-straightening machine being discussed here, the following requirements can be established for the electric drive:●regulation of speed within broad limits, including startup of the motors underload;●operation in the reverse regime;● a rigid characteristic ω = ƒ(M);●high degree of accuracy in maintaining the prescribed speed;●fully synchronous operation.The element base. The drive of the rollers was built with the use of asynchronous three-phase motors having a short-circuit rotor.The motors were designed by the German company VEM.They can continue to function under severe overloads and are reliable in operation.The motors are controlled by SIMOVERT frequency converters made by the German firm Siemens.Their modular design facilitates maintenance and repair, and the presence of a built-in microprocessor block makes it possible to execute most of the functions involved in controlling the operation of the drive (maintain the prescribed speed with a high degree ofstability, recalculate the frequency of rotation in accordance with the actual diameters of the rollers, diagnose the condition of the drive, control the drive’s operation, and exchange information on the PROFIBUS network).Motors of different powers are used in the system because of the differentiated distribution of the moments between the working ing different motors has made it possible to significantly reduce the cost of the electrical equipment and improve the performance characteristics of the machine as a whole.The machine has three main operating regimes: the working regime (semi-automatic and automatic), the transport regime, and the cassette replacement regime.Figure 2 shows a block diagram of the operations connected with realization of the working regime.In the semi-automatic variant of this regime, the operator controls the PSM from a control panel.In this case, the operator can do the following: choose the straightening regime from a database;correct the chosen regime;adjust the regime manually, which requires that the operator indicate the desired position of the bottom cassette (for five- or nine-roll straightening);adjust the gap between the top and bottom cassettes; set the coordinates for individual adjustment of the working rollers; choose the straightening speed and direction;generate a command to begin adjusting the machine to the specified regime.Fig. 2. Block diagram of the working regime of the PSM.The machine is adjusted to the chosen regime automatically.After the adjustment is completed, a signal is sent to the control panel indicating that the coordinates of the mechanisms have been changed and that the rollers have reached their prescribed working speeds.In the automatic variant of the working regime, the plate-straigthening machine is adjusted on the basis of data sent through a data network from a higher-level system. These data include the following information:●the thickness of the plate being straightened;●the group of steels (information on the properties of the material);●the temperature of the plate at the inlet to the PSM.The PSM is adjusted in several stages:●preliminary adjustment based on the plate thickness and steel group, for cold-rolledplates (t = 20°C);●further adjustment on the basis of data obtained from a pyrometer installed roughly 50m from the PSM;●final adjustment on the basis of data obtained from a pyrometer installed at theentrance to the machine.In the automatic variant, control over the roller conveyors adjacent to the machine is switched over to the control system of the PSM as the next plate approaches the machine.In this case, the plate cannot enter the working zone of the machine until the adjustment is completed.If it is necessary to pass a plate through the machine without straightening it, the machine is changed over to the transport regime.In this case, the top crossarm and the cassette are elevated a prescribed amount and the speed of the rollers is changed so that it is equal to the speed of the adjacent roller conveyors.The cassette replacement regime is used in the event of breakage of a roller or when it is necessary to regrind the working and backup rollers.In this case, the operator can control the operation of the auxiliary mechanisms:the spindle-locking mechanism, the roll-out cart, the mechanism that locks the bottom cassette and the cart in position, and the hydraulic cylinder that moves the cart.The mechanisms are fixed in position by means of noncontact transducers.PSM Control System. Control of the plate-straightening machine required the development of a powerful, high-capacity system that could provide the desired control accuracy in combination with rapid operation.The control system that was created is divided into two levels: the base level, and an upper level.The diagnostic system was created as a separate system.A second controller was also provided, to control the pump station of the PSM.The base level of the control system employs a SIMATIC S7 industrial programmable controller, while the upper level and the diagnostic system were built on the basis of standard computers.The computer used for the upper-level system also serves as the control panel for the PSM.Fig. 3. Network structure of the PSM control system.The different elements of the control system are linked by two loops of a PROFIBUS network (Fig.3).The first loop functions as the communications link between the controller, the upper-level computer, the diagnostics station, and the pump-station controller.The second loop links the PSM controller with the functional elements of the system (the frequency converters, linear displacement gages, and remote input/output module).The functions of the control system were divided between the base level and the upper level on the basis of the following principle: the base level was assigned all of the operations that involve receiving data from the sensors installed on the mechanisms, obtaining information from the automated process control system on the plate being straightened, and generating and transmitting control signals for the executive mechanisms (actuators); the upper level was assigned the functions of archiving the control points and monitoring the operation of the control panel.The following specific functions are performed by the base level of the automation system:●obtaining the assigned straightening parameters (roller speeds, the coordinates of thetop crossarm, and the coordinates of the rollers relative to the crossarm) from the upper-level system;●processing the parameters and sending corresponding control signals to the actuators;●obtaining information from the sensors installed on the mechanisms to determinewhether or not the PSM is properly set and ready for the straightening operation;●obtaining information from the feedback transducers installed on the mechanisms tocalculate the control actions;●analyzing the readings of the sensors to determine the accuracy of the data;TABLE 1. Specifications of the Plate-Straightening Machines●exchanging data with the pump-battery station (PBS) of the PSM and transmitting thestation’s operating parameters to the upper-level system for display;●receiving signals from the upper-level system for manual control of the machine andthe PBS;●obtaining initial data from the upper-level system for automatic correction andtransmission of the data in order to make the appropriate adjustments.The functions of the upper-level automation system are as follows:●entering data on the straightening regimes for subsequent selection of the regime andrecording that information in a database;●manually choosing the straightening regime from the database for the correspondingplate (this is done by the operator);●automatically choosing the straightening regime from the database on the basis ofinformation obtained from the upper-level system;●manually controlling the machine in the straightening and cassette-replacementregimes;●indicating the positions of the mechanisms based on readings from the sensors and thepositions of the limit switches;●indicating the presence of a plate in the working zone of the PSM;●indicating the temperature of the plate measured by the pyrometer;●visually representing the straightening regimes and machine adjustments;●visually representing the state of the machine’s mechanisms and the PBS fordiagnostic purposes.Remote input-output module ET200 is used to supply power to the unregulated drives.Thecabinet containing the relays and contacts for these drives is located a considerable distance from the e of the module has made it possible to significantly shorten the connecting cables.Diagnostic System. The heavy concentration of electrical and hydraulic equipment included as part of the PSM–equipment which is located an appreciable distance from the machine itself and is often in hard-to-reach places–makes it more difficult to service the machine and locate the source of problems.To facilitate maintenance of the PSM and shorten repair time, it was necessary to build an advanced diagnostic system.The system is based on an industrial computer installed at the control post.It diagnoses the state of various mechanisms of the PSM, as well as its hydraulic and electrical equipment.The system can be used to evaluate the condition of the automatic switches, the temperature sensors of the motors, the linear displacement gages, terminals of the local PROFIBUS network, the currents, speeds, and direction of rotation of the motors, and other equipment and parameters.The diagnostic system can also be used to establish the operating protocol of the PSM.Its archives contains data on the time and types of errors and equipment failures that occur, the coordinates of the mechanisms, motor currents and speeds, and other information.To make the control system more reliable, the software and hardware of the diagnostics station are identical to the corresponding components of the control system’s upper level.When problems occur with the operation of the control computer, the PSM control functions can be transferred to the computer of the diagnostic system.Conclusions.The NKMZ has worked with its original partners in the Commonwealth of Independent States (CIS) to successfully introduce plate-straightening machines equipped with a modern automated control system. Use of the machines makes it possible to minimize and almost completely eliminate the dependence of the quality of the finished plates on the skill of the machine operator.The control system, together with its convenient user interface,allows even personnel with no special training to quickly master the operation of the machine.The production of high-quality products is assured as a result of the exact movements of the machine’s mechanisms and the accuracy with which their positions are maintained, which owes to the use of precision equipment with proportional control and special control algorithms.In addition, the machine is equipped with a sophisticated diagnostic system which also records its key operating parameters.The availability of the system facilitates maintenance andrepair of the machine’s many complex components.译文：现代化矫直轧制薄品设备的自动化控制谢韦尔钢铁公司在2003年8月成功完成了新引进的规格为2800—5000米尔的直线式钢板矫直机（平台相关模型）。