機(jī)械畢業(yè)設(shè)計(jì)外文翻譯---數(shù)控機(jī)床

1、<p>　　What Is CNC</p><p>　　CNC stands for Computer Numerical Control and has been around since the early 1970''s. Prior to this, it was called NC, for Numerical Control. (In the early 1970'&

2、#39;s, computers were introduced in these controls, hence the name changed)While people in most walks of life have never heard of this term, CNC has touched almost every form of manufacturing process in one way or anothe

3、r. If you''ll be working in manufacturing, it''s likely that you''ll be dealing with CNC on a regular basis.</p><p>　　Before CNC</p><p>　　While there are exceptions to th

4、is statement, CNC machines typically replace (or work in conjunction with) some existing manufacturing process/es. Take one of the simplest manufacturing processes, drilling holes, for example.</p><p>　　A dr

5、ill press can of course be used to machine holes. (It''s likely that almost everyone has seen some form of drill press, even if you don''t work in manufacturing.) A person can place a drill in the drill c

6、huck that is secured in the spindle of the drill press. They can then (manually) select the desired speed for rotation (commonly by switching belt pulleys), and activate the spindle. Then they manually pull on the quill

7、lever to drive the drill into the workpiece being machined.</p><p>　　As you can easily see, there is a lot of manual intervention required to use a drill press to drill holes. A person is required to do some

8、thing almost every step along the way! While this manual intervention may be acceptable for manufacturing companies if but a small number of holes or workpieces must be machined, as quantities grow, so does the likelihoo

9、d for fatigue due to the tediousness of the operation. And do note that we''ve used one of the simplest machining operations (drilling) for ou</p><p>　　By comparison, the CNC equivalent for a drill p

10、ress (possibly a CNC machining center or CNC drilling & tapping center) can be programmed to perform this operation in a much more automatic fashion. Everything that the drill press operator was doing manually will n

11、ow be done by the CNC machine, including: placing the drill in the spindle, activating the spindle, positioning the workpiece under the drill, machining the hole, and turning off the spindle.</p><p>　　How CN

12、C works</p><p>　　There is another article included in this web site called The Basics of CNC that explains how to program, setup, and operate CNC machines in greater detail. Additionally, we offer a series o

13、f products aimed at helping you learn how to use CNC machines. Here we''re relating how CNC works in very general terms.</p><p>　　As you might already have guessed, everything that an operator would

14、be required to do with conventional machine tools is programmable with CNC machines. Once the machine is setup and running, a CNC machine is quite simple to keep running. In fact CNC operators tend to get quite bored dur

15、ing lengthy production runs because there is so little to do. With some CNC machines, even the workpiece loading process has been automated. (We don''t mean to over-simplify here. CNC operators are commonly requ&

16、lt;/p><p>　　Let''s look at some of the specific programmable functions.</p><p>　　Motion control</p><p>　　All CNC machine types share this commonality: They all have two or more

17、 programmable directions of motion called axes. An axis of motion can be linear (along a straight line) or rotary (along a circular path). One of the first specifications that implies a CNC machine''s complexity

18、is how many axes it has. Generally speaking, the more axes, the more complex the machine.</p><p>　　The axes of any CNC machine are required for the purpose of causing the motions needed for the manufacturing

19、 process. In the drilling example, these (3) axis would position the tool over the hole to be machined (in two axes) and machine the hole (with the third axis). Axes are named with letters. Common linear axis names are X

20、, Y, and Z. Common rotary axis names are A, B, and C.</p><p>　　Programmable accessories</p><p>　　A CNC machine wouldn''t be very helpful if all it could only move the workpiece in two or

21、 more axes. Almost all CNC machines are programmable in several other ways. The specific CNC machine type has a lot to do with its appropriate programmable accessories. Again, any required function will be programmable o

22、n full-blown CNC machine tools. Here are some examples for one machine type.</p><p>　　Machining centers</p><p>　　Automatic tool changer </p><p>　　Most machining centers can hold man

23、y tools in a tool magazine. When required, the required tool can be automatically placed in the spindle for machining.</p><p>　　Spindle speed and activation </p><p>　　The spindle speed (in revol

24、utions per minute) can be easily specified and the spindle can be turned on in a forward or reverse direction. It can also, of course, be turned off.</p><p><b>　　Coolant </b></p><p>

25、　　Many machining operations require coolant for lubrication and cooling purposes. Coolant can be turned on and off from within the machine cycle.</p><p>　　The CNC program</p><p>　　Think of givin

26、g any series of step-by-step instructions. A CNC program is nothing more than another kind of instruction set. It''s written in sentence-like format and the control will execute it in sequential order, step by st

27、ep.</p><p>　　A special series of CNC words are used to communicate what the machine is intended to do. CNC words begin with letter addresses (like F for feedrate（饋送率）, S for spindle speed, and X, Y & Z f

28、or axis motion). When placed together in a logical method, a group of CNC words make up a command that resemble a sentence.</p><p>　　For any given CNC machine type, there will only be about 40-50 words used

29、on a regular basis. So if you compare learning to write CNC programs to learning a foreign language having only 50 words, it shouldn''t seem overly difficult to learn CNC programming. </p><p>　　The C

30、NC control</p><p>　　The CNC control will interpret a CNC program and activate the series of commands in sequential order. As it reads the program, the CNC control will activate the appropriate machine functi

31、ons, cause axis motion, and in general, follow the instructions given in the program.</p><p>　　Along with interpreting the CNC program, the CNC control has several other purposes. All current model CNC contr

32、ols allow programs to be modified (edited) if mistakes are found. The CNC control allows special verification functions (like dry run) to confirm the correctness of the CNC program. The CNC control allows certain importa

33、nt operator inputs to be specified separate from the program, like tool length values. In general, the CNC control allows all functions of the machine to be manipulated</p><p>　　What is a CAM system?</p&g

34、t;<p>　　For simple application (like drilling holes), the CNC program can be developed manually. That is, a programmer will sit down to write the program armed only with pencil, paper, and calculator. Again, for s

35、imple applications, this may be the very best way to develop CNC programs.</p><p>　　As applications get more complicated, and especially when new programs are required on a regular basis, writing programs ma

36、nually becomes much more difficult. To simplify the programming process, a computer aided manufacturing (CAM) system can be used. A CAM system is a software program that runs on a computer (commonly a PC) that helps the

37、CNC programmer with the programming process. Generally speaking, a CAM system will take the tediousness and drudgery out of programming.</p><p>　　What is a DNC system?</p><p>　　Once the program

38、is developed(either manually or with a CAM system), it must be loaded into the CNC control. Though the setup person could type the program right into the control, this would be like using the CNC machine as a very expens

39、ive typewriter. If the CNC program is developed with the help of a CAM system, then it is already in the form of a text file . If the program is written manually, it can be typed into any computer using a common word pro

40、cessor (though most companies use a special</p><p>　　A DNC system is nothing more than a computer that is networked with one or more CNC machines. Until only recently, rather crude serial communications prot

41、ocol (RS-232c) had to be used for transferring programs. Newer controls have more current communications capabilities and can be networked in more conventional ways (Ethernet, etc.). Regardless of methods, the CNC progra

42、m must of course be loaded into the CNC machine before it can be run.</p><p><b>　　中文翻譯：</b></p><p><b>　　什么數(shù)控機(jī)床</b></p><p>　　數(shù)控機(jī)床代表計(jì)算機(jī)數(shù)字控制機(jī)床，并且從20世紀(jì)70年代以來(lái)一直受到

43、人們的關(guān)注。在這之前它被叫做NC，也就是數(shù)字控制（20世紀(jì)70年代早期，電腦被引用到這些控制里面，然后就變成CNC了）。雖然大多數(shù)其他領(lǐng)域的人從來(lái)沒(méi)有聽(tīng)說(shuō)過(guò)這個(gè)詞，但數(shù)控機(jī)床以一種或另一種幾乎涉及每一種形式的制造過(guò)程。如果你從事的是制造業(yè)，你將會(huì)經(jīng)常與數(shù)控機(jī)床打交道。 數(shù)控機(jī)床之前     盡管以上表述不盡如此，但數(shù)控機(jī)床顯然替代（或參與）了現(xiàn)有的一些制造過(guò)程。舉最簡(jiǎn)單的制造過(guò)程――鉆孔為例

44、。    臺(tái)式鉆床當(dāng)然可以用于加工孔。人們可以將鉆鉆頭裝在鉆夾中，鉆夾固定在臺(tái)鉆的　軸里；接著可以（手工）選擇所需的轉(zhuǎn)速（通常通過(guò)切換皮帶改變主軸轉(zhuǎn)速），并且啟動(dòng)主軸旋轉(zhuǎn)，然后操作鉆軸手柄，將鉆頭鉆入被加工的工件。    顯而易見(jiàn)，使用臺(tái)式鉆床鉆孔，需要許多人為的干預(yù)。幾乎全過(guò)程的每一步都需要人參與！如果只有數(shù)量不多的孔或工件要加工，這種人為干預(yù)對(duì)制造廠

45、來(lái)說(shuō)可能是可以接受的，但是，隨著生產(chǎn)數(shù)量的增加，由于操作乏味而產(chǎn)生疲勞的可能性也增大了。務(wù)必注意我們只是舉了最簡(jiǎn)單的操作之一（鉆削）為例，還有更加復(fù)雜的加工方式，對(duì)普通機(jī)床操</p><p>　　有另一個(gè)關(guān)于數(shù)控機(jī)床的網(wǎng)站解釋了怎么編程，設(shè)置并且操作數(shù)控機(jī)床的每一個(gè)細(xì)節(jié)。實(shí)際上，我們列舉了一系列產(chǎn)品就是為了幫助你學(xué)習(xí)如何使用數(shù)控機(jī)床，下面我們就舉幾個(gè)例子看看數(shù)控機(jī)床是如何效率的工作。  &#

46、160; 也許你已經(jīng)做出猜想：普通機(jī)床需要操作員做的每一件工作，在數(shù)控機(jī)床上都是由程序控制。一旦機(jī)床裝夾完畢并且運(yùn)行，數(shù)控機(jī)床容易保持自動(dòng)運(yùn)行狀態(tài)。實(shí)際上，由于無(wú)事可做，數(shù)控操作員在冗長(zhǎng)的生產(chǎn)運(yùn)行過(guò)程中會(huì)感到很無(wú)聊。在有些數(shù)控機(jī)床上，甚至工件裝夾的過(guò)程都是自動(dòng)化的（我們并不是說(shuō)是在這是多余的。數(shù)控機(jī)床操作者要做一些其他有關(guān)數(shù)控機(jī)床的事情就像測(cè)量車間并且調(diào)整使數(shù)控機(jī)床機(jī)器更好效率的工作）。讓我們來(lái)看一下具體的可編程功能。 運(yùn)

47、動(dòng)控制    所有的數(shù)控機(jī)床都有一個(gè)共同點(diǎn)：它們都有兩個(gè)或兩個(gè)以上的可編程運(yùn)動(dòng)方向，稱之為軸。軸運(yùn)動(dòng)可以是直線的（沿直線），也可以是旋轉(zhuǎn)的（沿圓周軌跡）。表征數(shù)控機(jī)床復(fù)雜程度的首要指標(biāo)之一是它有幾個(gè)軸。一般說(shuō)來(lái)，軸數(shù)越多，機(jī)床越復(fù)雜。    任何數(shù)控機(jī)床的軸是為了產(chǎn)生加工過(guò)程所的運(yùn)動(dòng)，在鉆削的例子中，這些(三個(gè))軸將刀具定位在待加工孔的上方兩軸運(yùn)動(dòng)，然后

48、加工孔。軸用字母命名</p><p><b>　　什么是CAM系統(tǒng)</b></p><p>　　對(duì)于簡(jiǎn)單的應(yīng)用分（比如鉆孔）數(shù)控程序可以手工編寫(xiě)。程序員只需要坐下用鉛筆，圖紙和計(jì)算器來(lái)編寫(xiě)程序。再一次提起，這也許是最好的方法來(lái)編寫(xiě)數(shù)控程序。</p><p>　　隨著應(yīng)用的越來(lái)越復(fù)雜，尤其是當(dāng)新項(xiàng)目需要定期的基礎(chǔ)上，人工編寫(xiě)程序顯得就越來(lái)越困難。

49、為了簡(jiǎn)化編程，就可以使用計(jì)算機(jī)輔助程序。CAM是一個(gè)在計(jì)算機(jī)上運(yùn)行的程序（通常是電腦）來(lái)幫助數(shù)控編程者編程。一般來(lái)說(shuō)。CAM程序編程將會(huì)很枯燥。</p><p><b>　　什么是DNC系統(tǒng)</b></p><p>　　一旦程序唄開(kāi)發(fā)出來(lái)（無(wú)論是人工編寫(xiě)還是用CAM程序編寫(xiě)），他都必須被載入到數(shù)控機(jī)床控制中心。雖然設(shè)置人員能夠鍵入程序，就好像把數(shù)控機(jī)床比作是一個(gè)比較昂

50、貴的打印機(jī)一樣。如果數(shù)控機(jī)床是用CAM編寫(xiě)的，那么他就以文本文件的格式存在。如果程序是由人工編寫(xiě)的，他能被同樣的形式輸入到任何一臺(tái)電腦上（當(dāng)然有些公司用一種特殊的數(shù)控機(jī)床形式）。無(wú)論是那種方式，該程序是一個(gè)文本文件并且能夠被轉(zhuǎn)換成數(shù)控機(jī)床識(shí)別的形式。DNC系統(tǒng)就是用于這一目的。</p><p>　　一個(gè)DNC系統(tǒng)只不過(guò)是一個(gè)計(jì)算機(jī)網(wǎng)絡(luò)與一個(gè)或多個(gè)數(shù)控機(jī)床相連。直到最近一段時(shí)間，RS-232c才用來(lái)改變程序方式。無(wú)