數(shù)控機床外文翻譯3

1、<p><b>　　英文原文</b></p><p>　　CNC machine tools</p><p>　　While the specific intention and application for CNC machines vary from one machine type to another, all forms of CNC have

2、common benefits. Here are but a few of the more important benefits offered by CNC equipment.</p><p>　　The first benefit offered by all forms of CNC machine tools is improved automation. The operator interven

3、tion related to producing workpieces can be reduced or eliminated. Many CNC machines can run unattended during their entire machining cycle, freeing the operator to do other tasks. This gives the CNC user several side b

4、enefits including reduced operator fatigue, fewer mistakes caused by human error, and consistent and predictable machining time for each workpiece. Since the machine will be r</p><p>　　The second major benef

5、it of CNC technology is consistent and accurate workpieces. Today's CNC machines boast almost unbelievable accuracy and repeatability specifications. This means that once a program is verified, two, ten, or one thous

6、and identical workpieces can be easily produced with precision and consistency.</p><p>　　A third benefit offered by most forms of CNC machine tools is flexibility. Since these machines are run from programs,

7、 running a different workpiece is almost as easy as loading a different program. Once a program has been verified and executed for one production run, it can be easily recalled the next time the workpiece is to be run. T

8、his leads to yet another benefit, fast change over. Since these machines are very easy to set up and run, and since programs can be easily loaded, they allow very</p><p>　　Motion control - the heart of CNC&l

9、t;/p><p>　　The most basic function of any CNC machine is automatic, precise, and consistent motion control. Rather than applying completely mechanical devices to cause motion as is required on most conventional

10、 machine tools, CNC machines allow motion control in a revolutionary manner2. All forms of CNC equipment have two or more directions of motion, called axes. These axes can be precisely and automatically positioned along

11、their lengths of travel. The two most common axis types are linear (driven along </p><p>　　Instead of causing motion by turning cranks and handwheels as is required on conventional machine tools, CNC machine

12、s allow motions to be commanded through programmed commands. Generally speaking, the motion type (rapid, linear, and circular), the axes to move, the amount of motion and the motion rate (feedrate) are programmable with

13、almost all CNC machine tools.</p><p>　　A CNC command executed within the control tells the drive motor to rotate a precise number of times. The rotation of the drive motor in turn rotates the ball screw. And

14、 the ball screw drives the linear axis (slide). A feedback device (linear scale) on the slide allows the control to confirm that the commanded number of rotations has taken place3. Refer to fig.1.</p><p><

15、;b>　　Fig.1</b></p><p>　　Though a rather crude analogy, the same basic linear motion can be found on a common table vise. As you rotate the vise crank, you rotate a lead screw that, in turn, drives t

16、he movable jaw on the vise. By comparison, a linear axis on a CNC machine tool is extremely precise. The number of revolutions of the axis drive motor precisely controls the amount of linear motion along the axis.</p&

17、gt;<p>　　How axis motion is commanded - understanding coordinate systems</p><p>　　It would be infeasible for the CNC user to cause axis motion by trying to tell each axis drive motor how many times to

18、 rotate in order to command a given linear motion amount4. (This would be like having to figure out how many turns of the handle on a table vise will cause the movable jaw to move exactly one inch!) Instead, all CNC cont

19、rols allow axis motion to be commanded in a much simpler and more logical way by utilizing some form of coordinate system. The two most popular coordinate systems</p><p>　　The program zero point establishes

20、the point of reference for motion commands in a CNC program. This allows the programmer to specify movements from a common location. If program zero is chosen wisely, usually coordinates needed for the program can be tak

21、en directly from the print.</p><p>　　With this technique, if the programmer wishes the tool to be sent to a position one inch to the right of the program zero point, X1.0 is commanded. If the programmer wish

22、es the tool to move to a position one inch above the program zero point, Y1.0 is commanded. The control will automatically determine how many times to rotate each axis drive motor and ball screw to make the axis reach th

23、e commanded destination point . This lets the programmer command axis motion in a very logical manner. Refer t</p><p><b>　　Fig.2</b></p><p><b>　　Fig.3</b></p><

24、p>　　All discussions to this point assume that the absolute mode of programming is used6. The most common CNC word used to designate the absolute mode is G90. In the absolute mode, the end points for all motions will b

25、e specified from the program zero point. For beginners, this is usually the best and easiest method of specifying end points for motion commands. However, there is another way of specifying end points for axis motion.<

26、;/p><p>　　In the incremental mode (commonly specified by G91), end points for motions are specified from the tool's current position, not from program zero. With this method of commanding motion, the progra

27、mmer must always be asking "How far should I move the tool?" While there are times when the incremental mode can be very helpful, generally speaking, this is the more cumbersome and difficult method of specifyi

28、ng motion and beginners should concentrate on using the absolute mode.</p><p>　　Be careful when making motion commands. Beginners have the tendency to think incrementally. If working in the absolute mode (as

29、 beginners should), the programmer should always be asking "To what position should the tool be moved?" This position is relative to program zero, NOT from the tools current position.</p><p>　　Asid

30、e from making it very easy to determine the current position for any command, another benefit of working in the absolute mode has to do with mistakes made during motion commands. In the absolute mode, if a motion mistake

31、 is made in one command of the program, only one movement will be incorrect. On the other hand, if a mistake is made during incremental movements, all motions from the point of the mistake will also be incorrect.</p&g

32、t;<p>　　Assigning program zero</p><p>　　Keep in mind that the CNC control must be told the location of the program zero point by one means or another. How this is done varies dramatically from one CNC

33、 machine and control to another8. One (older) method is to assign program zero in the program. With this method, the programmer tells the control how far it is from the program zero point to the starting position of the

34、machine. This is commonly done with a G92 (or G50) command at least at the beginning of the program and possibly at the </p><p>　　Another, newer and better way to assign program zero is through some form of

35、offset. Refer to fig.4. Commonly machining center control manufacturers call offsets used to assign program zero fixture offsets. Turning center manufacturers commonly call offsets used to assign program zero for each to

36、ol geometry offsets.</p><p>　　Fig. 4 </p><p>　　Flexible manufacturing cells</p><p>　　A flexible manufacturing cell (FMC) can be considered as a flexible manufacturing subsystem.

37、The following differences exist between the FMC and the FMS:</p><p>　　An FMC is not under the direct control of thecentral computer. Instead, instructions from the centralcomputer are passed to the cell co

38、ntroller.</p><p>　　The cell is limited in the number of part families itcan manufacture.</p><p>　　The following elements are normally found in an FMC:</p><p>　　Cell controller</

39、p><p>　　Programmable logic controller (PLC)</p><p>　　More than one machine tool</p><p>　　A materials handling device (robot or pallet)</p><p>　　The FMC executes fixed mach

40、ining operations with parts flowing sequentially between operations. </p><p>　　High speed machining</p><p>　　The term High Speed Machining (HSM) commonly refers to end milling at high rotational

41、 speeds and high surface feeds. For instance, the routing of pockets in aluminum airframe sections with a very high material removal rate1. Over the past 60 years, HSM has been applied to a wide range of metallic and non

42、-metallic workpiece materials, including the production of components with specific surface topography requirements and machining of materials with hardness of 50 HRC and above. With most steel c</p><p>　　Fo

43、r many components, the production process involves a combination of these options and in the case of dies and moulds it also includes time consuming hand finishing. Consequently, production costs can be high and lead tim

44、es excessive.</p><p>　　It is typical in the die and mould industry to produce one or just a few tools of the same design. The process involves constant changes to the design, and because of these changes the

45、re is also a corresponding need for measuring and reverse engineering .</p><p>　　The main criteria is the quality level of the die or mould regarding dimensional, geometric and surface accuracy. If the quali

46、ty level after machining is poor and if it cannot meet the requirements, there will be a varying need of manual finishing work. This work produces satisfactory surface accuracy, but it always has a negative impact on the

47、 dimensional and geometric accuracy.</p><p>　　One of the main aims for the die and mould industry has been, and still is, to reduce or eliminate the need for manual polishing and thus improve the quality and

48、 shorten the production costs and lead times.</p><p>　　Main economical and technical factors for the development of HSM</p><p><b>　　Survival</b></p><p>　　The ever increa

49、sing competition in the marketplace is continually setting new standards. The demands on time and cost efficiency is getting higher and higher. This has forced the development of new processes and production techniques t

50、o take place. HSM provides hope and solutions...</p><p><b>　　Materials</b></p><p>　　The development of new, more difficult to machine materials has underlined the necessity to find n

51、ew machining solutions. The aerospace industry has its heat resistant and stainless steel alloys. The automotive industry has different bimetal compositions, Compact Graphite Iron and an ever increasing volume of aluminu

52、m3. The die and mould industry mainly has to face the problem of machining high hardened tool steels, from roughing to finishing.</p><p><b>　　Quality</b></p><p>　　The demand for high

53、er component or product quality is the result of ever increasing competition. HSM, if applied correctly, offers a number of solutions in this area. Substitution of manual finishing is one example, which is especially imp

54、ortant on dies and moulds or components with a complex 3D geometry.</p><p><b>　　Processes</b></p><p>　　The demands on shorter throughput times via fewer setups and simplified flows (

55、logistics) can in most cases, be solved by HSM. A typical target within the die and mould industry is to completely machine fully hardened small sized tools in one setup. Costly and time consuming EDM processes can also

56、be reduced or eliminated with HSM.</p><p>　　Design & development</p><p>　　One of the main tools in today's competition is to sell products on the value of novelty. The average product li

57、fe cycle on cars today is 4 years, computers and accessories 1.5 years, hand phones 3 months... One of the prerequisites of this development of fast design changes and rapid product development time is the HSM technique.

58、 </p><p>　　Complex products</p><p>　　There is an increase of multi-functional surfaces on components, such as new design of turbine blades giving new and optimized functions and features. Earlie

59、r designs allowed polishing by hand or with robots (manipulators). Turbine blades with new, more sophisticated designs have to be finished via machining and preferably by HSM . There are also more and more examples of th

60、in walled workpieces that have to be machined (medical equipment, electronics, products for defence, computer parts)</p><p>　　Production equipment</p><p>　　The strong development of cutting mate

61、rials, holding tools, machine tools, controls and especially CAD/CAM features and equipment, has opened possibilities that must be met with new production methods and techniques5.</p><p>　　Definition of HSM&

62、lt;/p><p>　　Salomon's theory, "Machining with high cutting speeds..." on which, in 1931, took out a German patent, assumes that "at a certain cutting speed (5-10 times higher than in conventi

63、onal machining), the chip removal temperature at the cutting edge will start to decrease..."</p><p>　　Given the conclusion:" ... seems to give a chance to improve productivity in machining with con

64、ventional tools at high cutting speeds..."</p><p>　　Modern research, unfortunately, has not been able to verify this theory totally. There is a relative decrease of the temperature at the cutting edge t

65、hat starts at certain cutting speeds for different materials.</p><p>　　The decrease is small for steel and cast iron. But larger for aluminum and other non-ferrous metals. The definition of HSM must be based

66、 on other factors.</p><p>　　Given today's technology, "high speed" is generally accepted to mean surface speeds between 1 and 10 kilometers per minute or roughly 3 300 to 33 000 feet per minute

67、. Speeds above 10 km/min are in the ultra-high speed category, and are largely the realm of experimental metal cutting. Obviously, the spindle rotations required to achieve these surface cutting speeds are directly relat

68、ed to the diameter of the tools being used. One trend which is very evident today is the use of very large cutter d</p><p>　　There are many opinions, many myths and many different ways to define HSM.</p&g

69、t;<p>　　Maintenance and troubleshooting</p><p>　　Maintenance for a horizontal MC</p><p>　　The following is a list of required regular maintenance for a Horizontal Machining Center as show

70、n in fig.5. Listed are the frequency of service, capacities, and type of fluids required. These required specifications must be followed in order to keep your machine in good working order and protect your warranty.</

71、p><p><b>　　fig. 5 </b></p><p><b>　　Daily</b></p><p>　　Top off coolant level every eight hour shift (especially during heavy TSC usage).</p><p>　　Ch

72、eck way lube lubrication tank level.</p><p>　　Clean chips from way covers and bottom pan.</p><p>　　Clean chips from tool changer.</p><p>　　Wipe spindle taper with a clean cloth rag

73、and apply light oil.</p><p><b>　　Weekly</b></p><p>　　?Check for proper operation of auto drain on filter regulator. </p><p>　　On machines with the TSC option, clean the

74、 chip basket on the coolant tank.</p><p>　　Remove the tank cover and remove any sediment inside the tank. Be careful to disconnect the coolant pump from the controller and POWER OFF the control before workin

75、g on the coolant tank . Do this monthly for machines without the TSC option.</p><p>　　Check air gauge/regulator for 85 psi.</p><p>　　For machines with the TSC option, place a dab of grease on th

76、e V-flange of tools. Do this monthly for machines without the TSC option.</p><p>　　Clean exterior surfaces with mild cleaner. DO NOT use solvents.</p><p>　　Check the hydraulic counterbalance pre

77、ssure according to the machine's specifications.</p><p>　　Place a dab of grease on the outside edge of the fingers of the tool changer and run through all tools".</p><p><b>　　Mont

78、hly</b></p><p>　　Check oil level in gearbox. Add oil until oil begins dripping from over flow tube at bottom of sump tank.</p><p>　　Clean pads on bottom of pallets.</p><p>　　C

79、lean the locating pads on the A-axis and the load station. This requires removing the pallet.</p><p>　　?Inspect way covers for proper operation and lubricate with light oil, if necessary.</p><p&g

80、t;　　Six months</p><p>　　Replace coolant and thoroughly clean the coolant tank.</p><p>　　Check all hoses and lubrication lines for cracking.</p><p><b>　　Annually</b></

81、p><p>　　?Replace the gearbox oil. Drain the oil from the gearbox, and slowly refill it with 2 quarts of Mobil DTE 25 oil.</p><p>　　?Check oil filter and clean out residue at bottom for the lubric

82、ation chart.</p><p>　　Replace air filter on control box every 2 years.</p><p>　　Mineral cutting oils will damage rubber based components throughout the machine.</p><p>　　Troubleshoo

83、ting</p><p>　　This section is intended for use in determining the solution to a known problem. Solutions given are intended to give the individual servicing the CNC a pattern to follow in, first, determining

84、 the problem's source and, second, solving the problem.</p><p>　　Use common sense</p><p>　　Many problems are easily overcome by correctly evaluating the situation. All machine operations are

85、 composed of a program, tools, and tooling. You must look at all three before blaming one as the fault area. If a bored hole is chattering because of an overextended boring bar, don't expect the machine to correct th

86、e fault.</p><p>　　Don't suspect machine accuracy if the vise bends the part. Don't claim hole mis-positioning if you don't first center-drill the hole.</p><p>　　Find the problem firs

87、t</p><p>　　Many mechanics tear into things before they understand the problem, hoping that it will appear as they go. We know this from the fact that more than half of all warranty returned parts are in good

88、 working order. If the spindle doesn't turn, remember that the spindle is connected to the gear box, which is connected to the spindle motor, which is driven by the spindle drive, which is connected to the I/O BOARD,

89、 which is driven by the MOCON, which is driven by the processor. The moral here is don't</p><p>　　Don tinker with the machine</p><p>　　There are hundreds of parameters, wires, switches, etc.

90、, that you can change in this machine. Don't start randomly changing parts and parameters. Remember, there is a good chance that if you change something, you will incorrectly install it or break something else in the

91、 process6. Consider for a moment changing the processor's board. First, you have to download all parameters, remove a dozen connectors, replace the board, reconnect and reload, and if you make one mistake or bend one

92、 tiny pin it </p><p><b>　　英文譯文</b></p><p><b>　　數(shù)控機床</b></p><p>　　雖然各種數(shù)控機床的功能和應(yīng)用各不相同，但它們有著共同的優(yōu)點。這里是數(shù)控設(shè)備提供的比較重要的幾個優(yōu)點。</p><p>　　各種數(shù)控機床的第一個優(yōu)點是自動化程度提

93、高了。零件制造過程中的人為干預(yù)減少或者免除了。整個加工循環(huán)中，很多數(shù)控機床處于無人照看狀態(tài)，這使操作員被解放出來，可以干別的工作。數(shù)控機床用戶得到的幾個額外好處是：數(shù)控機床減小了操作員的疲勞程度，減少了人為誤差，工件加工時間一致而且可預(yù)測。由于機床在程序的控制下運行，與操作普通機床的機械師要求的技能水平相比，對數(shù)控操作員的技能水平要求（與基本加工實踐相關(guān)）也降低了。</p><p>　　數(shù)控技術(shù)的第二個優(yōu)點是工件

94、的一致性好，加工精度高。現(xiàn)在的數(shù)控機床宣稱的精度以及重復(fù)定位精度幾乎令人難以置信。這意味著，一旦程序被驗證是正確的，可以很容易地加工出2個、10個或1000個相同的零件，而且它們的精度高，一致性好。</p><p>　　大多數(shù)數(shù)控機床的第三個優(yōu)點是柔性強。由于這些機床在程序的控制下工作，加工不同的工件易如在數(shù)控系統(tǒng)中裝載一個不同的程序而己。一旦程序驗證正確，并且運行一次，下次加工工件的時候，可以很方便地重新調(diào)用程

95、序。這又帶來另一個好處—可以快速切換不同工件的加工。由于這些機床很容易調(diào)整并運行，也由于很容易裝載加工程序，因此機床的調(diào)試時間很短。這是當(dāng)今準(zhǔn)時生產(chǎn)制造模式所要求的。</p><p>　　運動控制—CNC的核心</p><p>　　任何數(shù)控機床最基本的功能是具有自動、精確、一致的運動控制。大多數(shù)普通機床完全運用機械裝置實現(xiàn)其所需的運動，而數(shù)控機床是以一種全新的方式控制機床的運動。各種數(shù)控設(shè)

96、備有兩個或多個運動方向，稱為軸。這些軸沿著其長度方向精確、自動定位。最常用的兩類軸是直線軸（沿直線軌跡）和旋轉(zhuǎn)軸（沿圓形軌跡）。</p><p>　　普通機床需通過旋轉(zhuǎn)搖柄和手輪產(chǎn)生運動，而數(shù)控機床通過編程指令產(chǎn)生運動。通常，幾乎所有的數(shù)控機床的運動類型（快速定位、直線插補和圓弧插補）、移動軸、移動距離以及移動速度（進給速度）都是可編程的。</p><p>　　數(shù)控系統(tǒng)中的CNC指令命令驅(qū)

97、動電機旋轉(zhuǎn)某一精確的轉(zhuǎn)數(shù)，驅(qū)動電機的旋轉(zhuǎn)隨即使?jié)L珠絲杠旋轉(zhuǎn)，滾珠絲杠將旋轉(zhuǎn)運動轉(zhuǎn)換成直線軸（滑臺）運動?；_上的反饋裝置（直線光柵尺）使數(shù)控系統(tǒng)確認指令轉(zhuǎn)數(shù)已完成，參見圖1。</p><p><b>　　圖1 </b></p><p>　　普通的臺虎鉗上有著同樣的基本直線運動，盡管這是相當(dāng)原始的類比。旋轉(zhuǎn)虎鉗搖柄就是旋轉(zhuǎn)絲杠，絲杠帶動虎鉗鉗口移動。與臺虎鉗相比，數(shù)控機

98、床的直線軸是非常精確的，軸的驅(qū)動電機的轉(zhuǎn)數(shù)精確控制直線軸的移動距離。</p><p>　　軸運動命令的方式--理解坐標(biāo)</p><p>　　對CNC用戶來說，為了達到給定的直線移動量而指令各軸驅(qū)動電機旋轉(zhuǎn)多少轉(zhuǎn)，從而使坐標(biāo)軸運動，這種方法是不可行的。（這就好像為了使鉗口準(zhǔn)確移動1英寸需要計算出臺虎鉗搖柄的轉(zhuǎn)數(shù)?。┦聦嵣希械臄?shù)控系統(tǒng)都能通過采用坐標(biāo)系的形式以一種較為簡單而且合理的方式來指

99、令軸的運動。數(shù)控機床上使用最廣泛的兩種坐標(biāo)系是直角坐標(biāo)系和極坐標(biāo)系。目前用得較多的是直角坐標(biāo)系。</p><p>　　編程零點建立數(shù)控程序中運動命令的參考點。這使得操作員能從一個公共點開始指定軸運動。如果編程零點選擇恰當(dāng)，程序所需坐標(biāo)通?？蓮膱D紙上直接獲得。</p><p>　　如果編程員希望刀具移動到編程零點右方1英寸（25.4毫米）的位置，則用這種方法指令X1.0即可。如果編程員希望刀

100、具移動到編程零點上方1英寸的位置，則指令Y1.0。數(shù)控系統(tǒng)會自動確定（計算）各軸驅(qū)動電機和滾珠絲杠要轉(zhuǎn)動多少轉(zhuǎn)，使坐標(biāo)軸到達指令的目標(biāo)位置。這使編程員以非常合理的方式命令軸的運動，參見圖2和圖3.</p><p><b>　　理解絕對和相對運動</b></p><p>　　至此，所有的討論都假設(shè)采用的是絕對編程方式。用于指定絕對方式的最常用的數(shù)控代碼是G90。絕對方式

101、下，所有運動終點的指定都是以編程零點為起點。對初學(xué)者來說，這通常是最好也是最容易的指定軸運動終點的方法，但還有另外一種指定軸運動終點的方法。</p><p>　　增量方式（通常用G91指定）下，運動終點的指定是以刀具的當(dāng)前位置為起點，而不是編程零點。用這種方法指定軸運動，編程員往往會問“我該將刀具移動多遠的距離？”，盡管增量方式多數(shù)時候很有用，但一般說來，這種方法指定軸運動較麻煩、困難，初學(xué)者應(yīng)該重點使用絕對方式

102、。</p><p><b>　　圖2</b></p><p><b>　　圖3</b></p><p>　　指令軸運動時一定要小心。初學(xué)者往往以增量方式思考問題。如果工作在絕對方式（初學(xué)者應(yīng)該如此），編程員應(yīng)始終在問“刀具應(yīng)該移動到什么位置？”，這個位置是相對于編程零點這個固定位置而言，而不是相對于刀具當(dāng)前位置。</