外文翻譯-機(jī)床實(shí)踐

1、<p>　　附錄2 外文翻譯（外文部分）</p><p>　　ADVANCED MACHINING PROCESSES</p><p>　　As the hardware of an advanced technology becomes more complex, new and visionary approaches to the processing of materia

2、ls into useful products come into common use. This has been the trend in machining processes in recent years.. Advanced methods of machine control as well as completely different methods of shaping materials have permitt

3、ed the mechanical designer to proceed in directions that would have been totally impossible only a few years ago.</p><p>　　Parallel development in other technologies such as electronics and computers have ma

4、de available to the machine tool designer methods and processes that can permit a machine tool to far exceed the capabilities of the most experienced machinist.</p><p>　　In this section we will look at CNC m

5、achining using chip-making cutting tools. CNC controllers are used to drive and control a great variety of machines and mechanisms, Some examples would be routers in wood working; lasers, plasma-arc, flame cutting, and w

6、aterjets for cutting of steel plate; and controlling of robots in manufacturing and assembly. This section is only an overview and cannot take the place of a programming manual for a specific machine tool. Because of the

7、 tremendous growth in n</p><p>　　Advantages of Numerical Control</p><p>　　A manually operated machine tool may have the same physical characteristics as a CNC machine, such as size and horsepowe

8、r. The principles of metal removal are the same. The big gain comes from the computer controlling the machining axes movements. CNC-controlled machine tools can be as simple as a 2-axis drilling machining center (Figure

9、O-1). With a dual spindle machining center, the low RPM, high horsepower spindle gives high metal removal rates. The high RPM spindle allows the efficient use o</p><p>　　Since the chip-making process is cont

10、rolled by the proper feeds and speeds, time savings can be achieved by faster rapid feed rates. Rapid feeds have increased from 60 to 200 to 400 and are now often approaching 1000 inches per minute (IPM). These high feed

11、 rates can pose a safety hazard to anyone within the working envelope of the machine tool.</p><p>　　Complex contoured shapes were extremely difficult to product prior to CNC machining .CNC has made the machi

12、ning of these shapes economically feasible. Design changes on a part are relatively easy to make by changing the program that directs the machine tool.</p><p>　　A CNC machine produces parts with high dimensi

13、onal accuracy and close tolerances without taking extra time or special precautions, CNC machines generally need less complex work-holding fixtures, which saves time by getting the parts machined sooner. Once a program i

14、s ready and production parts, each part will take exactly the same amount of time as the previous one. This repeatability allows for a very precise control of production costs. Another advantage of CNC machining is the e

15、limination of </p><p>　　With modern CNC machine tools a trained machinist can program and product even a single part economically .CNC machine tools are used in small and large machining facilities and range

16、 in size from tabletop models to huge machining centers. In a facility with many CNC tools, programming is usually done by CNC programmers away from the CNC tools. The machine control unit (MCU) on the machine is then us

17、ed mostly for small program changes or corrections. Manufacturing with CNC tools usually requires</p><p>　　CNC controls are generally divided into two basic categories. One uses a ward address format with co

18、ded inputs such as G and M codes. The other users a conversational input; conversational input is also called user-friendly or prompted input. Later in this section examples of each of these programming formats in machin

19、ing applications will be describes.</p><p>　　CAM and CNC</p><p>　　CAM systems have changed the job of the CNC programmer from one manually producing CNC code to one maximizing the output of CNC

20、machines. Since CNC machine tools are made by a great number of manufacturers, many different CNC control units are in use. Control units from different manufacturers use a variety of program formats and codes. Many CNC

21、code words are identical for different controllers, but a great number vary from one to another.</p><p>　　To produce an identical part on CNC machine tools with different controllers such as one by FANCU, OK

22、UMA or DYNAPATH, would require completely different CNC codes. Each manufacturer is constantly improving and updating its CNC controllers. These improvements often include additional code words plus changes in how the ex

23、isting code works.</p><p>　　A CAM systems allows the CNC programmer to concentrate on the creation of an efficient machining process, rather then relearning changed code formats. A CNC programmer looks at th

24、e print of a part and then plans the sequence of machining operations necessary to make it (Figure O-3). This plan includes everything, from the selection of possible CNC machine tools, to which tooling to use, to how th

25、e part is held while machining takes place. The CNC programmer has to have a thorough understanding o</p><p>　　Another area of major importance to the programmer is the knowledge of machining processes. An e

26、xample would be the selection of the surface finish requirement specified in the part print. The sequence of machining processes is critical to obtain acceptable results. Cutting tool limitations have to be considered an

27、d this requires knowledge of cutting tool materials, tool types, and application recommendations.</p><p>　　A good programmer will spend a considerable amount of time in researching the rapidly growing volume

28、 of new and improved tools and tool materials. Often the tool that was on the cutting edge of technology just two years ago is now obsolete. Information on new tools can come from catalogs or tool manufacturers' tool

29、ing engineers. Help in tool selection or optimum tool working conditions can also be obtained from tool manufacturer software. Examples would be Kennametal's "TOOLPRO", software design</p><p>　

30、　Software for a machining center application would be Ingersoll Tool Company's "Actual Chip Thickness", a program used to calculate the chip thickness in relation to feed-per-tooth for a milling cutter, esp

31、ecially during a shallow finishing cut. Ingersoll's "Rigidity Analysis" software ealculates tool deflection for end mills as a function of tool stiffness and tool force.</p><p>　　To this point

32、we looked at some general qualifications that a programmer should possess. Now we examine how a CAM system works. Point Control Company's SmartCam system uses the following approach. First, the programmer makes a men

33、tal model of the part to be machined. This includes the kind of machining to be performed-turning or milling. Then the part print is studied to develop a machining sequence, roughing and finishing cuts, drilling, tapping

34、, and boring operations. What work-holding device </p><p>　　This line of information describes the tool by number, type, and size and includes the appropriate cutting speed and feed rate. After all the selec

35、ted tools are entered, the file is saved.</p><p>　　The second programming step is the making of the part. This represents a graphic modeling of the projected machining operation. After selecting a tool from

36、the prepared JOBPLAN, parameters for the cutting operation are entered. For a drill, once the coordinate location of the hole and the depth are given, a circle appears on that spot. If the location is incorrect, the UNDO

37、 command erases this entry and allows you to give new values for this operation. When an end mill is being used, cutting mov</p><p>　　At any time during programming, the command SHOWPATH will show the actual

38、 toolpath for each of the programmed tools. The tools will be displayed in the sequence in which they will be used during actual machining. If the sequence of a tool movement needs to be changed, a few keystrokes will to

39、 that.</p><p>　　Sometimes in CAM the programming sequence is different from the actual machining order. An example would be the machining of a pocket in a part. With CAM, the finished pocket outline is progr

40、ammed first, then this outline is used to define the roughing cuts to machine the pocket. The roughing cuts are computer generated from inputs such as depth and width of cut and how much material to leave for the finish

41、cut. Different roughing patterns can be tried out to allow the programmer to select the m</p><p>　　A CAM system lets the programmer view the graphics model from varying angles, such as a top, front, side, or

42、 isometric view. A toolpath that looks correct from a top view, may show from a front view that the depth of the cutting tool is incorrect. Changes can easily be made and seen immediately.</p><p>　　When the

43、toolpath and the sequence of operations are satisfactory, machine ready code has to be made. This is as easy as specifying the CNC machine that is to be used to machine the part. The code generator for that specific CNC

44、machine during processing accesses four different files. The JOBPLAN file for the tool information and the GRAPHICE file for the toolpath and cutting sequence. It also uses the MACHINE DEFINE file which defines the CNC c

45、ode words for that specific machine. This file also</p><p><b>　　CAD/CAM</b></p><p>　　Another method of creating toolpath is with the use of a Computer-aided Drafting (CAD) file. Most

46、 machine drawings are created using computers with the description and part geometry stored in the computer database. SmartCAM, though its CAM CONNECTION, will read a CAD file and transfer its geometry represents the par

47、t profile, holes, and so on. The programmer still needs to prepare a JOBPLAN with all the necessary tools, but instead of programming a profile line by line, now only a tool has to be</p><p>　　The work area

48、around the machine needs to be kept clean and clear of obstructions to prevent slipping or tripping. Machine surfaces should not be used as worktables. Use proper lifting methods to handle heavy workpieces, fixtures, or

49、heavy cutting tools. Make measurements only when the spindle has come to a complete standstill. Chips should never be handled with bare hands.</p><p>　　Before starting the machine make sure that the work-hol

50、ding device and the workpiece are securely fastened. When changing cutting tools, protect the workpiece being machined from damage, and protect your hands from sharp cutting edges. Use only sharp cutting tools. Check tha

51、t cutting tools are installed correctly and securely.</p><p>　　Do not operate any machine controls unless you understand their function and what they will do.</p><p>　　The Early Development Of N

52、umerically Controlled Machine Tools</p><p>　　The highly sophisticated CNC machine tools of today, in the vast and diverse range found throughout the field of manufacturing processing, started from very humbl

53、e beginnings in a number of the major industrialized countries. Some of the earliest research and development work in this field was completed in USA and a mention will be made of the UK's contribution to this numeri

54、cal control development.</p><p>　　A major problem occurred just after the Second World War, in that progress in all areas of military and commercial development had been so rapid that the levels of automatio

55、n and accuracy required by the modern industrialized world could not be attained from the lab our intensive machines in use at that time. The question was how to overcome the disadvantages of conventional plant and curre

56、nt manning levels. It is generally ackonwledged that the earliest work into numerical control was the study</p><p>　　At about the same times as these American advances in machine tool control were taking Pla

57、ce, Alfred Herbert Limited in the United Kingdom had their first Mutinous path control system which became available in 1956.Over the next few years in both the USA and Europe, further development work occurred. These ea

58、rly numerical control developments were principally for the aerospace industry, where it was necessary to cut complex geometric shapes such as airframe components and turbine blades. In para</p><p>　　The ear

59、ly NC machines were, in the main, based upon a modified milling machine with this concept of control being utilized on turning, punching, grinding and a whole host of other machine tools later. Towards the end of the 195

60、0s,hydrostatic slideways were often incorporated for machine tools of highly precision, which to sonic extent overcame the section problem associated with conventional slideway response, whiles averaging-out slideway ina

61、ccuracy brought about a much increased preasion in th</p><p>　　In the mid 1960s,a UK company, Molins, introduced their unique "System 24" which was meant represent the ability of a system to machin

62、e for 24 hours per day. It could be thought of as a "machining complex" which allowed a series of NC single purpose machine tools to be linked by a computerized conveyor system. This conveyor allowed the work p

63、ieces to be palletized and then directed to as machine tool as necessary. This was an early, but admirable, attempt at a form of Flexible manufacturing Syst</p><p>　　The early to mid-1970s was a time of revo

64、lutionary in the area of machine tool controller development, when the term computerized numerical control (CNC) became a reality. This new breed of controllers gave a company the ability to change work piece geometries,

65、 together with programs, easily with the minimum of development and lead time, allowing it to be economically viable to machine small batches, or even one-off successfully. The dream of allowing a computerized numerical

66、controller the flex</p><p>　　The multipie benefits of cheaper electorics with greater reliability have result in the CNC fitted to the machine tools today, with the power and sophistication progtessing consi

67、derably in the last few years, allowing an almost artificial intelligence(AI) to the latest systems. Over the years, the machine tools builders have produced a large diversity in the range of applications of CNC and just

68、 some of those development will be reviewed in Volume Ⅲ。</p><p>　　With any capital cost item, such as a CNC machine tool, it is necessary for a company to undergo a feasibility study in order to ascertain wh

69、ether the purchase of new plant is necessary and can be justified over a relatively short pay-back period. These thoughts and other circial decisions will be the subject of the next section which is concerned with the ec

70、onomic justification for CNC.</p><p>　　附錄3外文翻譯（中文部分）</p><p><b>　　機(jī)床實(shí)踐</b></p><p>　　隨著先進(jìn)科技的硬件變得復(fù)雜化，把原料加工成為有用產(chǎn)品的理想的、新的加工手段得到了普遍應(yīng)用。這已經(jīng)成為近幾年機(jī)床加工的發(fā)展趨勢(shì)。先進(jìn)的機(jī)床控制方法和完全不同的材料成形方法還迫

71、使機(jī)械設(shè)計(jì)人員進(jìn)行前幾年還完全沒有進(jìn)行的方向（研究）。</p><p>　　其他科技如電子技術(shù)和計(jì)算機(jī)技術(shù)的并行發(fā)展，使機(jī)床設(shè)計(jì)者有辦法讓機(jī)床具有超過絕大多數(shù)經(jīng)驗(yàn)豐富的機(jī)械師（在普通機(jī)床上）所具有的加工能力。</p><p>　　在這個(gè)部分我們來(lái)看數(shù)控機(jī)床切削使用的工具。CNC控制器能被用來(lái)驅(qū)動(dòng)和控制多種機(jī)床和機(jī)構(gòu)。舉幾個(gè)例子，如刳刨機(jī)進(jìn)行木料加工；激光、離子弧、火焰切削、噴水切削鋼板；在

72、制造和裝配中機(jī)器人的控制等。本書的這個(gè)部分僅是一般介紹而不能作為專業(yè)機(jī)床的設(shè)計(jì)手冊(cè)。由于計(jì)算機(jī)能力和容量的巨大增長(zhǎng)，機(jī)床的控制技術(shù)很頻繁地發(fā)生著變化。在機(jī)床控制發(fā)展中的精彩部分是在每個(gè)先進(jìn)技術(shù)上的使用變得很容易了。</p><p><b>　　NC的優(yōu)勢(shì)</b></p><p>　　人工操作機(jī)床可能有和CNC機(jī)床一樣的物理特性，例如馬力和尺寸，其金屬切削原理也是一樣的

73、。CNC最大的好處是通過計(jì)算機(jī)控制機(jī)床刀具的運(yùn)動(dòng)，CNC控制的機(jī)床可能簡(jiǎn)單得象2刀鉆床或復(fù)雜得象5刀的加工中心（如圖O-1）。兩軸的加工機(jī)床，其特點(diǎn)是低轉(zhuǎn)速、高馬力軸有高進(jìn)給率，高轉(zhuǎn)速軸允許高效的高速切削刀具如鉆石和小直徑的刀具的使用（如圖O-2）。它的切削刀具是標(biāo)準(zhǔn)的刀具如磨床的刀具、鉆子、鉆探工具或車刀，這些刀具依賴于所使用的機(jī)床型號(hào)。切削速度和進(jìn)給量要象在其他操作機(jī)床中一樣是正確的。CNC機(jī)床的最大優(yōu)勢(shì)來(lái)自無(wú)錯(cuò)的和快速的可能運(yùn)動(dòng)

74、的控制。數(shù)控機(jī)床不會(huì)在一次加工完成后停下來(lái)計(jì)劃下一次的運(yùn)動(dòng)，它不會(huì)疲勞，它是不中斷的機(jī)床，機(jī)床只有在它切削的時(shí)候才有生產(chǎn)性。</p><p>　　當(dāng)切削過程被適當(dāng)?shù)倪M(jìn)給量和切削速度控制時(shí)，時(shí)間的節(jié)約可以通過快速的進(jìn)給率來(lái)完成?？焖龠M(jìn)給從60發(fā)展到200到400到現(xiàn)在已接近每分1000英寸了。這樣高的進(jìn)給率對(duì)在機(jī)床工作區(qū)的任何人構(gòu)成了安全威脅。</p><p>　　在CNC機(jī)床之前，復(fù)雜形狀

75、的加工是極困難的。CNC使這些形狀的加工制造在經(jīng)濟(jì)上是可行的。零件的設(shè)計(jì)變化通過改變控制機(jī)床的程序而相對(duì)容易實(shí)現(xiàn)。</p><p>　　CNC機(jī)床不需要額外的時(shí)間和特別的預(yù)防就可生產(chǎn)高精度的嚴(yán)格公差的零件。CNC使機(jī)床不需要復(fù)雜的夾具，這使零件很快被加工從而節(jié)約了時(shí)間。一旦程序準(zhǔn)備好并加工零件，每個(gè)零件都將花與第一個(gè)一樣的時(shí)間。這個(gè)一致性允許很精確地控制加工成本。數(shù)控機(jī)床的另一個(gè)優(yōu)勢(shì)是大量存貨的減少，零件可以在需

76、要時(shí)再被加工。在傳統(tǒng)制造中，為了增加效率，通常一大批零件被同時(shí)加工。有了CNC即使一件也能夠被經(jīng)濟(jì)地加工。在很多情況下，一個(gè)CNC機(jī)床完成了要建立幾臺(tái)相同傳統(tǒng)機(jī)床才能做的操作。</p><p><b>　　CAM和CNC</b></p><p>　　CAM系統(tǒng)改變了CNC程序員的工作，即從手工編制CNC代碼到CNC機(jī)床的輸出最大值。自從手工CNC機(jī)床被一大批廠家生產(chǎn)以

77、來(lái)，許多不同的CNC控制單元就被使用了。各個(gè)不同的廠家的控制單元使用各個(gè)不相同的程序與代碼。許多CNC代碼語(yǔ)句可被不同的控制器識(shí)別。但其間還有眾多的區(qū)別。為了在有著不同控制器（如FAWC、OKUMA、或DYNAPATH）生產(chǎn)一個(gè)可互換的零件，將需要完全不同的CNC代碼。每個(gè)制造商在不斷地提高和更新其CNC控制。這些改進(jìn)通常包括附加的代碼語(yǔ)句在已有代碼如何工作上的變化。CAM系統(tǒng)允許CNC程序員在高效的加工過程的建立上濃縮、精選、而不重新

78、學(xué)習(xí)已改變的代碼格式。一個(gè)CNC程序員看著一個(gè)零件的圖紙，并且設(shè)計(jì)必要的機(jī)床操作來(lái)制造這個(gè)零件（如圖O-3）。這個(gè)設(shè)計(jì)包括以下每個(gè)因素，從可能使用的CNC機(jī)床的選擇，到機(jī)床的使用選擇，再到加工時(shí)的零件裝夾的選擇。CNC程序員必須對(duì)這個(gè)即將寫入程序的CNC機(jī)床的能力和局限有一個(gè)完全的了解。機(jī)床主參數(shù)如馬力主軸馬力、最大轉(zhuǎn)速、工作臺(tái)的重量、工具的尺寸限制、加工變化能力等只是值得考慮的影響程序的因素中的一些。對(duì)程序員要求的另一個(gè)最重要領(lǐng)域是制

79、</p><p>　　為加工中心使用的軟件是ENGERSOLL CUTTING TOOL公司的ACTUAL CHIP THICKNESS。程序被用來(lái)計(jì)算磨床每次進(jìn)的給量，特別是在微量的光潔度加工中。ENGERSOLL的“精密分析”軟件作為機(jī)床剛度和機(jī)床力的功能來(lái)。在這一點(diǎn)上我們觀察一些廣泛的設(shè)計(jì)人員應(yīng)掌握的規(guī)格?，F(xiàn)在我們測(cè)試CAM系統(tǒng)怎樣工作。點(diǎn)控公司（POINT CPNTROLL COMPANY）的SMARTC

80、AM 系統(tǒng)使用接下來(lái)的手段：首先設(shè)計(jì)人員使用一個(gè)金屬零件模型去加工。這包括的加工方式是------車或磨。接著這個(gè)零件圖被研究來(lái)做成機(jī)床加工工序，粗加工或精加工、鉆、沖、磨等操作。被使用的裝夾夾具是虎鉗，抓盤還是卡盤？這些考慮之后，計(jì)算機(jī)輸出就可開始了。首先還是工藝卡的建立。這個(gè)工藝卡由各種記錄（例如：英制或公制，機(jī)床類型、零件卡、切削材料類型、安裝記錄、和所需要機(jī)床的描述</p><p>　　其第二個(gè)編程的步驟

81、是零件的制造。這描述了一個(gè)所設(shè)計(jì)機(jī)床操作的生動(dòng)模型。從已準(zhǔn)備好的JOBPLAN中選好機(jī)床后，切削加工的參數(shù)就被編入。對(duì)鉆床而言，一旦孔的位置坐標(biāo)和深度被給出，一個(gè)孔就給出現(xiàn)在那點(diǎn)。如果其位置是錯(cuò)的，其撤消命令選擇這一記錄，并允許你給這個(gè)工序新的值。當(dāng)端面磨時(shí)，切削運(yùn)動(dòng)通常被定義為弧。當(dāng)一條直線被編入程序， TOOLPATH就會(huì)生動(dòng)的顯示，其錯(cuò)誤也可立即被糾正。</p><p>　　在程序運(yùn)行的任意時(shí)刻，命令SHO

82、WPATH會(huì)顯示當(dāng)前的刀具軌跡，也會(huì)顯示刀具在實(shí)際加工時(shí)的使用順序。當(dāng)?shù)毒哌\(yùn)動(dòng)順序需要改變時(shí)，可用一個(gè)按鍵來(lái)實(shí)現(xiàn)它。</p><p>　　有時(shí)，CAM的程序順序和實(shí)際加工的順序是各不相同的。某部件的孔的加工就是一個(gè)例子。首先，在CAM中編譯已加工孔的外部輪廓，再把外部輪廓當(dāng)成粗基準(zhǔn)來(lái)加工內(nèi)孔。根據(jù)輸入切削的寬和深以及完成切削需切去的材料，計(jì)算機(jī)產(chǎn)生粗切削的加工程序。程序員嘗試各種粗基準(zhǔn)，以便選出最有效的切削加工方

83、法。由于用不同的顏色代表不同的刀具，所以觀察不同刀具的軌跡是很容易的。一個(gè)CAM系統(tǒng)可讓程序員從不同的角度觀察圖形，比如說從頂部、正面、側(cè)面或立體圖。俯視中正確的刀具軌跡，在正視圖中，切削的深度是不正確的，其變化顯而易見。</p><p>　　當(dāng)?shù)毒呗窂郊捌漤樞蚨ê煤螅瑱C(jī)床的代碼應(yīng)被做好。這和詳細(xì)指明加工這個(gè)部件的CNC機(jī)床一樣容易。運(yùn)行時(shí)，指定機(jī)床的代碼發(fā)生器相當(dāng)于四個(gè)不同的鍵。JOBPLAN文件運(yùn)行時(shí)，表示刀

84、具信息，GRAPHICS文件表示刀具路徑和切削順序。也用MACHINE DEFINE文件表示CNC代碼命令。這個(gè)文件可提供最大的進(jìn)給速度、轉(zhuǎn)速、加工時(shí)間等等。當(dāng)代碼發(fā)生器完成時(shí)，加工的計(jì)劃時(shí)間就確定了。這個(gè)時(shí)間是根據(jù)進(jìn)給速度，運(yùn)行的距離，兩點(diǎn)間在最大進(jìn)給時(shí)間速度下無(wú)切削運(yùn)動(dòng)的時(shí)間，換刀時(shí)間等等確定的。這個(gè)計(jì)劃加工時(shí)間可通過改變安裝后達(dá)到更智能的移動(dòng)速度或創(chuàng)造一種更有效的刀具軌跡來(lái)調(diào)整。所需的總時(shí)間的確定可用來(lái)估計(jì)生產(chǎn)費(fèi)用。若不只一個(gè)CN

85、C機(jī)床可以來(lái)加工這工件，制作代碼和比較在加工總時(shí)間可以表示一個(gè)機(jī)床是否比另一個(gè)機(jī)床該更有效，</p><p><b>　　CAM/CAD</b></p><p>　　另一個(gè)確立刀具路徑的方法是借助計(jì)算機(jī)輔助繪圖。大多數(shù)的機(jī)械繪圖使用電腦存儲(chǔ)了零件平面圖形及其注釋。格式化的CAM通過它的CAM CONNECTION，可以讀一個(gè)CAD文件和轉(zhuǎn)移它的圖形到它的輪廓基準(zhǔn)中去。

86、這圖形可表示零件的外形輪廓、孔等等。程序員仍需準(zhǔn)備一個(gè)工藝卡，含有所用需要的刀具。但相對(duì)于用一排排程序來(lái)表示外形，現(xiàn)在刀具只用現(xiàn)有的輪廓來(lái)表示即可。另外，使用SHOWPATH功能可以顯示每個(gè)刀具的路徑和他們的順序。CAD/CAM相互影響的方向的不斷探索和發(fā)展將會(huì)改變他們的工作方式。一些CAD和CAM程序，如果在相同的計(jì)算機(jī)上下載，可同時(shí)使用一些按鍵、圖紙和程序，使其能相互匹配。</p><p>　　機(jī)床周圍應(yīng)該保

87、持清潔，并且無(wú)導(dǎo)致絆倒或打滑的障礙物。機(jī)床表面不應(yīng)該被用作工作臺(tái)。用正確的方法提升重的工作部件，或固定重的切削刀具。啟動(dòng)機(jī)床之前，確定工作裝置和工件是否安全的固定了 。換刀時(shí)，保護(hù)工件不受傷害，同時(shí)保護(hù)你的手不被鋒利的尖角弄傷。使用鋒利的切削刀具時(shí)，檢查切削刀具是否正確和安全的安裝。</p><p>　　直到你理解它們的功能和動(dòng)作方可操作這臺(tái)機(jī)床。</p><p>　　數(shù)控機(jī)床刀具早期的發(fā)

88、展</p><p>　　今天在機(jī)器化大生產(chǎn)領(lǐng)域中千形百態(tài)，結(jié)構(gòu)復(fù)雜的刀具，起源于一些主要的工業(yè)國(guó)，開始很簡(jiǎn)陋。這個(gè)領(lǐng)域中，最早的一些研究和發(fā)展完成于美國(guó)，并記載了UK關(guān)于數(shù)控發(fā)展方面的貢獻(xiàn)。第二次世界大戰(zhàn)后的一個(gè)主要問題是，商業(yè)和軍隊(duì)迅速發(fā)展，在勞動(dòng)力密集的加工中，現(xiàn)代工業(yè)界所需的自動(dòng)化與精確度不可獲得。問題是怎么樣來(lái)克服來(lái)自常規(guī)的加工方法和手工制作的不足。通常認(rèn)為，關(guān)于數(shù)控的研究是1949年美國(guó)政府的授權(quán)。結(jié)論

89、就是致使美國(guó)空軍與Parsons公司簽約，讓他們找到一種靈活的、有力的制造系統(tǒng)，它能擴(kuò)大生產(chǎn)。麻省理工大學(xué)開始進(jìn)入研究，而Parsons公司使之發(fā)展起來(lái)。在1949—1951期間，他們聯(lián)合發(fā)明了一種可適合多種刀具的第一個(gè)數(shù)控系統(tǒng)。辛辛那提機(jī)床刀具公司把他們的一個(gè)28英寸的“Hydro—Tel”軍用機(jī)床改裝為三軸自動(dòng)機(jī)床，改變了它們的外部輪廓。在控制桌面位置，典型的機(jī)床是三軸連續(xù)曲線的機(jī)床刀具，它能產(chǎn)生一個(gè)所需要的形狀或曲線，可能的話，通

90、過一個(gè)連續(xù)的滑移實(shí)現(xiàn)。</p><p>　　與美國(guó)機(jī)床刀具控制發(fā)展的同時(shí)，UK中的ALIFRED Herber產(chǎn)生了第一臺(tái)NC機(jī)床。1956年更可靠的曲線路徑控制系統(tǒng)開始使用。幾年后，在USA與歐洲開始了更深遠(yuǎn)的研究。早期數(shù)控的發(fā)展主要為了航空業(yè)，它需要切削加工復(fù)雜的幾何形狀，如機(jī)件部件與渦輪機(jī)葉片。在航空所需要的復(fù)雜的控制系統(tǒng)發(fā)展的同時(shí)，點(diǎn)與點(diǎn)控制器發(fā)展起來(lái)，更廣泛的用于加工當(dāng)中。較簡(jiǎn)單的點(diǎn)與點(diǎn)機(jī)床比復(fù)雜的連續(xù)

91、路徑的同類產(chǎn)品便宜一些，并在用于需要精確定位的加工中。作為一個(gè)鉆操作的機(jī)床刀具的點(diǎn)至點(diǎn)移動(dòng)例子，典型的運(yùn)動(dòng)是快速經(jīng)過在鉆主軸下的工件，鉆空后，迅速的滑移的運(yùn)動(dòng)可能過每軸以連續(xù)且獨(dú)立的方式獲得。分開的控制可由每軸完成，在早期的點(diǎn)到點(diǎn)機(jī)床中，選取路徑不很重要，但它必須避免在獲得多需要精度中所產(chǎn)生的沖擊。所以，趨勢(shì)下一點(diǎn)的方向必須是相同的。最早的這些點(diǎn)到點(diǎn)機(jī)床長(zhǎng)循環(huán)的球行螺絲釘，這就意味著那些運(yùn)動(dòng)必須很緩慢，移動(dòng)中遇到的沖擊不可避免，關(guān)于這個(gè)

92、問題下章有更詳細(xì)的敘述。</p><p>　　早期的NC機(jī)床，主要的在磨床基礎(chǔ)發(fā)展起來(lái)的，控制的概念主要用于形成，打孔，磨削以及后來(lái)的大量的另外的機(jī)床刀具。19世紀(jì)50年代以來(lái)，流件滑動(dòng)在高精度的機(jī)床中常被結(jié)合使用，它在某種程度上克服了常規(guī)滑軌相關(guān)的問題，然而平均輸出導(dǎo)軌的不精確度對(duì)刀具要求更高并增加了它的控制特性。</p><p>　　加工中心的概念是早期工作的結(jié)果，它允許機(jī)床在一個(gè)安裝

93、上對(duì)工件進(jìn)行多種加工，而不需要把工件轉(zhuǎn)移到另外的刀具下。一個(gè)加工中心不同于一個(gè)磨床，相互要在于它能利用轉(zhuǎn)移裝置和分離器自動(dòng)的把切削刀具從刀具庫(kù)中轉(zhuǎn)移到主軸上。用這種方式，自動(dòng)換刀特性使這加工中心高效的加工多種部件，用新刀具代替舊刀具或預(yù)選刀具，使得現(xiàn)今的加工過程循環(huán)操作。</p><p>　　在19世紀(jì)60年代中時(shí)，一個(gè)UK公司，Molins介紹他們獨(dú)特的“系統(tǒng)24”意思是一天能加工24小時(shí)。它可被認(rèn)為是系列但作

94、用刀具通過計(jì)算機(jī)上控制的運(yùn)輸系統(tǒng)連接起來(lái)的復(fù)合機(jī)床。這個(gè)運(yùn)輸裝置讓工件放在托盤上送至所需的機(jī)床刀具下。這是早期情形，是值得欽佩的。靈活制作系統(tǒng)方面嘗試都失敗了，它的主要短處是僅僅一小部分的零件種類可隨時(shí)加工，而更少的工件需要完成于它相同的操作。事實(shí)上它的利用水平很低，機(jī)床刀具昂貴會(huì)導(dǎo)致加工頻繁時(shí)的“頸瓶”現(xiàn)象，于是進(jìn)一步限制了整個(gè)操作。</p><p>　　13世紀(jì)70年代初中葉，是機(jī)床刀具控制器變革時(shí)期，這個(gè)時(shí)

95、期，CNC成為了一個(gè)現(xiàn)實(shí)。新的控制器的產(chǎn)生便使公司可通過改變程序改變了一個(gè)工件外形。微型技術(shù)的發(fā)展，可成功的加工一批或一個(gè)2全件。當(dāng)兩個(gè)相關(guān)的因素存在后，在一個(gè)生產(chǎn)環(huán)境中，讓CNC實(shí)現(xiàn)靈活且輕松的編程的夢(mèng)想變成為現(xiàn)實(shí)。這些現(xiàn)實(shí)是：</p><p>　　集成電路的發(fā)展，它減少了電路的尺寸，使得維護(hù)便利且有利于設(shè)計(jì)的標(biāo)準(zhǔn)化。</p><p>　　計(jì)算機(jī)的體積減小，從而它的生產(chǎn)費(fèi)用也極大的降低。

96、價(jià)格便宜，性能穩(wěn)定等多種優(yōu)點(diǎn)使得今天的CNC安裝在機(jī)床刀具上。隨著它的不斷發(fā)展成熟，使在高級(jí)的CNC系統(tǒng)上可安上人工智能。這些年來(lái)，刀具制作者已經(jīng)制作了多種多樣的刀具可用在CNC系統(tǒng)上，其中的一部分在第3冊(cè)中將被討論。</p><p>　　由資金耗費(fèi)項(xiàng)目上的考慮，就CNC機(jī)床刀具而言，為了明確新計(jì)劃是否必要或證明在短期內(nèi)實(shí)現(xiàn)資金回收，一個(gè)公司必須進(jìn)行可行性分析。這些想法及重要的決定將會(huì)成為考慮CNC系統(tǒng)經(jīng)濟(jì)性調(diào)整