模具專業(yè)英語課件-Unit_Four.ppt

1、Unit Four Manufacturing Technology of Mold,Passage One Numerical Control,Passage Two Electric Discharge Machining,Passage Three Wire Electrical Discharge Machining（Wire EDM）,Passage Four Rapid Prototyping and Manufacturing,Passage Five Electrochemical Machining（ECM）,Passage One Numerical Control,1,M

2、any types of machine tools and other industrial processes are equipped for numerical control， commonly called NC. The earliest forms of NC were developed in the 1950s when the movements of the axes of machine tools were assigned numerical values to facilitate the replacement of hand wheels and dials

3、 by control logic . NC requires accurate product design values; early systems were limited by the lack of detailed analyses for the geometrical drawings of the components to be manufactured. Later in the decade， this problem was overcome when computers were developed that could describe geometric to

4、ol movements as functions of a part -programming language. One of the best known of these early languages of tool instructions was APT （Automatically Programmed Tools）.,Unit Four Manufacturing Technology of Mold,Unit Four Manufacturing Technology of Mold,A significant development of the early 1960s

5、was a system known as Sketchpad， which enabled engineers to draw designs on a cathode -ray tube by using a light pen and a keyboard. When this system was connected to a computer， it enabled designers to study drawings interactively and facilitated the modification of their designs. A NC system or de

6、vice is one that controls the actions of a machine or process by the direct insertion of numerical data at some points， the system also must automatically interpret at least some portion of the data. Various kinds of numerical control systems use data coded in the form of numbers， letters， symbols，

7、words， or a combination of these forms.,Unit Four Manufacturing Technology of Mold,The instructions necessary for machining a part by NC are derived from the part drawing and are written in coded form on a program manuscript . The following kinds of data may be included on the manuscript: sequence o

8、f operation， kind of operation， depth of cut， coordinate dimensions for the center of the cutting tool， feed rate， spindle speed， tool number， and other miscellaneous operations. The coded information is punched into a ribbon of one -inch -wide machine -control tape with a tape -punching machine sim

9、ilar to a typewriter. The tape， usually made of paper or plastic， is inserted into the NC system， which is connected to the machine tool. The NC,Unit Four Manufacturing Technology of Mold,system interprets the information on the tape， thus activates relays and electrical circuits that cause the mach

10、ines servomechanisms and other controls to perform a sequence of operations automatically. On some NC systems， the coded information is inserted into the machines on punched cards or magnetic tape instead of punched tape. The tape can be stored for future use on the same machine or on others like it

11、 at any location. NC machines can produce parts accurately to tolerances of 0.0001 to 0.001 inch（0.0025 to 0.025 mm） depending on the design of the machine， the NC system， and other factors， such as environmental temperature. NC systems on machine tools can be classified into two basic types: point

12、-to -point（Fig.4 -1） and continuous -path （Fig.4 -2）. Point -to -point systems， commonly used on,Unit Four Manufacturing Technology of Mold,machines that perform hole -machining and straight -line milling operations， are relatively simple to program and do not require the aid of a computer.,Fig.4 -1

13、 Point -to -point Fig.4 -2 Continuous -path,Unit Four Manufacturing Technology of Mold,Continuous -path NC systems are commonly used on machines that perform contouring operations， such as milling machines， lathes， flame -cutting machines， and drafting machines . Program preparation for continuous -

14、path machines is more complex and usually requires the aid of a computer. An entire manufacturing technology known as CAD/CAM has developed around the NC concept and， in addition， CNC with its powerful microprocessors and other enabling technologies proffered from the personal computer has enabled t

15、he NC concept to branch into many variants， even a variant that is essentially record/playback. The latter of which are known in the industry as“teach lathes”. In addition， powerful and well -crafted human/machine,Unit Four Manufacturing Technology of Mold,interfaces allow the machine operator to pr

16、epare programs by means of interactive displays which request only the definition of the machining operation and its required parameters（such as a“pocket” and its dimensions） and not the actual tool paths with all the calculations that are required there. Anyone who knows machining concepts and blue

17、print interpretation can produce programs at the machine without the need for CAD/CAM. Nonetheless， the vast majority of programs are now produced with the aid of CAD/CAM and， for most users， CNC today（for all its gigahertz microprocessors and megabyte of real time kernel software） is conceptually l

18、ittle different from,Unit Four Manufacturing Technology of Mold,the first NC demonstrated by MIT in 1952. If there is a notable difference in concept， it is that CNC is no longer just for the spindle/cutting tool process of stock removal. It is for any processes that can be carried on machine tool m

19、otion platforms and that benefit from the separation of programming from operations， that is， from the CAD/CAM technology. These include lasing， welding， friction stir welding， ultrasonic welding， flame cutting， bending， spinning， pinning， gluing， fabric cutting， sewing， tape and fiber placement， ro

20、uting， picking and placing （ PnP）， sawing and undoubtedly， the industrial processes of tomorrow.,Unit Four Manufacturing Technology of Mold, Later in the decade， this problem was overcome when computers were developed that could describe geometric tool movements as functions of a part -programming l

21、anguage. 在稍后的十年內(nèi)，當(dāng)計算機的發(fā)展可以將幾何刀具的運動描述成零件加工語言的函數(shù)時，這個問題就被解決了。 “that could describe geometric tool movements as functions of a part -programming language”作為定語從句修飾“developed”，“as functions of a part -programming language”在從句中作狀語。 The tape can be stored for future use on the same machine or on others like

22、 it at any location. 打孔帶能被儲存以便將來在任何場所用在相同的機器或同它一樣的其他機器上。,Notes:,Unit Four Manufacturing Technology of Mold,NC systems on machine tools can be classified into two basic types: point -to -point（Fig.4 -1） and continuous -path（Fig.4 -2）. 機床上的數(shù)控系統(tǒng)可分為兩種基本類型:點到點型（圖4 -1）和連續(xù)路徑型（圖4 -2）。 點到點型也稱點位控制，從一個點位移到另一個點

23、位，它追求的結(jié)果是最終位置的準(zhǔn)確性，并能在最終位置上保持，而并不重視兩點之間的路徑。 連續(xù)路徑型也稱輪廓控制，能夠連續(xù)控制兩個或兩個以上坐標(biāo)方向的聯(lián)合運動。,New Words and Expressions ：,Unit Four Manufacturing Technology of Mold,machine tools機床 numerical control數(shù)字控制 axes ksi z n.軸 facilitatef siliteit vt.幫助 dial d i l n.刻度盤 control logic控制邏輯 geometrical drawing幾何制圖 instruction

24、in str k n n.指令 APT自動編程工具 sketchpad sket p d n.幾何畫板 cathode -ray陰極射線 interactively int r ktivli adv.交互式地,Unit Four Manufacturing Technology of Mold,interactively int r ktivli adv.交互式地 modification m difi kei n n.修改，修正 interpretin t prit v.解釋 derivedi raiv vt.得自 manuscript m njuskript n.手稿，原稿 sequenc

25、e si kw ns n.順序，次序 depth of cut切削深度 feed rate進給速度 spindle speed轉(zhuǎn)速 miscellaneousmisi leinj s adj.混雜的 punch into打入 tape -punching machine打孔機 servomechanism s v u mek niz m n. 伺服機構(gòu),Unit Four Manufacturing Technology of Mold,punched card打孔卡片 magnetic tape磁帶 tolerance t l r ns n.公差 environmentalin v i r

26、n mentl adj.環(huán)境的 point -to -point點到點 continuous -path連續(xù)路徑 contouringk n tu ri n.造型 drafting machine繪圖儀 complex k mpleks adj.復(fù)雜的 microprocessorm ikr u pr uses（r） n. 微處理器 phenomenonfi n min n n.現(xiàn)象 variant v ri nt n.變量 human/machine interface人/機交互界面,Unit Four Manufacturing Technology of Mold,definition

27、defi ni n n.定義 parameterp r mit n.參數(shù) blueprint blu print n.設(shè)計圖，藍圖 nonetheless n n les adv.雖然如此，但是 vastv st adj.巨大的，大量的 gigahertz i h ts n.千兆赫 megabyte me b it n.兆字節(jié) kernel k nl n.核心，要點 demonstrate dem nstreit vt.示范 lasing leisi n.發(fā)射激光 welding weldi n.焊接 friction stir welding摩擦焊接,Unit Four Manufactur

28、ing Technology of Mold,ultrasonic welding超聲波焊接 flame cutting氣割 bending bendi n.彎曲 spinning spini n.旋壓加工 pinning pini n.銷連接，釘壓 gluing lu i n.膠粘 fabric cutting簾布裁斷 sewing s ui n.縫紉 routing ru ti n.造模銑切 picking and placing（PnP）分揀放置 sawing s i n.鋸割,Exercises：,Answer the following questions according to

29、the text above. 1. What is the numerical control? Try to describe it using the words in this passage or of your own. 2. What kinds of data may be included on the program manuscript? 3. What are two basic types of numerically controlled machine tools? 4. Describe the processes that can be benefit fro

30、m the CAD/CAM technology.,Unit Four Manufacturing Technology of Mold,Translate the following words into Chinese: 1. machine tools 2. numerical control 3. control logic 4. geometrical drawing 5. Automatically Programmed Tools 6. depth of cut 7. feed rate 8. spindle speed 9. tape -punching machine 10.

31、 point -to -point 11. continuous -path 12. drafting machine,Unit Four Manufacturing Technology of Mold,Translate the passage below into Chinese: Numerical control has been in use for almost 40 years. Since its inception，it has been improved continually. Each improvement has added a new benefit or im

32、proved an existing benefit of NC as compared with traditional manual machine operation. During this period， a body of knowledge has developed from the actual benefits that can be derived from NC. There is a general consensus among manufacturing professionals that the principal benefits derived from

33、NC are the following:,Unit Four Manufacturing Technology of Mold,Unit Four Manufacturing Technology of Mold,Better planning Greater -flexibility Easier scheduling Less setup， lead，and processing time Better machine utilization Lower overall tooling costs Greater uniformity in cutting Greater accurac

34、y in cutting A higher degree of interchangeability of parts and tools More accurate cost estimates Permanent memory of how a part was made,參考譯文：,數(shù)控技術(shù),許多類型的機床及其他工業(yè)加工設(shè)備都配備有數(shù)字控制裝置，通常稱為NC。數(shù)控技 術(shù)的最早形式產(chǎn)生于19世紀(jì)50年代，那時機床主軸運動的數(shù)值化控制推動了用邏輯控制來替代的手輪和刻度盤的人工控制。數(shù)控技術(shù)需要正確的產(chǎn)品設(shè)計數(shù)值;先前的系統(tǒng)由于缺乏詳細(xì)的制造零件幾何制圖的分析計算而受到限制。在稍后的十年內(nèi)，當(dāng)

35、計算機的發(fā)展可以將幾何刀具的運動描述成零件加工語言的函數(shù)時，這個問題就被解決了。APT語言（自動編程工具）是早先最好的加工指令語言之一。,譯,Unit Four Manufacturing Technology of Mold,Unit Four Manufacturing Technology of Mold,19世紀(jì)60年代初期，一個重要的發(fā)展是幾何畫板系統(tǒng)，這個系統(tǒng)能讓工程師利用光筆和鍵盤在陰極射線管屏幕上設(shè)計圖形。當(dāng)這個系統(tǒng)被連接到計算機上時，能夠使設(shè)計者交互式地學(xué)習(xí)制圖且?guī)椭麄冏鲈O(shè)計的修改。 數(shù)控系統(tǒng)或設(shè)備是一種通過在某些點上直接插入數(shù)字?jǐn)?shù)據(jù)來控制機床或加工操作的 系統(tǒng);系統(tǒng)也必須

36、能夠自動地解釋最基本部分的數(shù)據(jù)。不同類型的數(shù)字控制系統(tǒng)使用的數(shù)據(jù)指令多以數(shù)字、文字、符號、詞組的形式或以幾種形式的組合來實現(xiàn)。 數(shù)控加工零件必需的指令來自于部分的制圖數(shù)據(jù)并且以編碼的形式寫在源程序上。 源程序上可能包括下列類型的數(shù)據(jù):操作的順序、操作的類型、切削深度、刀具中心的尺寸 坐標(biāo)、進給速度、主軸轉(zhuǎn)速、工具編號及其他各種的操作。,Unit Four Manufacturing Technology of Mold,代碼信息被類似于打字機的打孔機打入一條一英寸寬的機器控制帶上。打孔帶通常由紙或塑料做成，被插入連接到機床的數(shù)控系統(tǒng)中。數(shù)控系統(tǒng)解釋紙帶上的信息，從而啟動繼電器，使機器的伺服機構(gòu)

37、和其他控制機構(gòu)的電路能自動地進行一系列的操作。在一些數(shù)控系統(tǒng)中，代碼信息在代替了打孔帶的打孔卡片或磁帶上被插入到機器中。打孔帶能被儲存以便將來在任何場所用在相同的機器或同它一樣的其他機器上。在機床設(shè)計、數(shù)控系統(tǒng)和其他的因素，如環(huán)境溫度的允許下，數(shù)控機床能加工的零件的公差在0.00010.001 英寸（0.00250.025 mm）之間。 機床上的數(shù)控系統(tǒng)可分為兩種基本類型:點到點型（圖4 -1）和連續(xù)路徑型（圖4 -2）。點到點系統(tǒng)普遍應(yīng)用于進行孔加工和直線銑削等的機床中，其相對編程簡單且不需要計算機輔助。,Unit Four Manufacturing Technology of Mold,

38、圖4 -1 點到點型 圖4 -2 連續(xù)路徑型,連續(xù)路徑數(shù)控系統(tǒng)普遍應(yīng)用于造型加工的機床，如銑床、車床、氣割機和繪圖儀等。連續(xù)路徑加工的程序準(zhǔn)備更復(fù)雜且通常需要計算機的輔助。,Unit Four Manufacturing Technology of Mold,一種稱為CAD/CAM的完整的制造技術(shù)圍繞著數(shù)控概念發(fā)展起來了。除此之外，由個 人計算機提供的有著強大的微處理器和其他促成技術(shù)的CNC（計算機數(shù)字控制）技術(shù)已經(jīng)使數(shù)控觀念產(chǎn)生了許多分支，一個分支本質(zhì)上是一個記錄或再生。后者在工業(yè)中被稱為“教師車床”。 除此之外，強大的、工藝良好的人/機交互界面讓機床操作員編寫程序時只需知道機 床操作的定義

39、及其必需參數(shù)（例如一個“端口”及其尺寸），并不需要所有的真實刀具路徑的計算。任何人只要知道加工概念和理解設(shè)計圖就可以在機床上編寫程序而不需要 CAD/CAM的輔助。雖然如此 ,現(xiàn)在絕大多數(shù)的程序還,Unit Four Manufacturing Technology of Mold,是需要借助于CAD/CAM來進行編 寫的。對于大多數(shù)使用者來說，今天的CNC（盡管它有千兆赫微處理器和兆字節(jié)的實時核 心軟件）與1952年麻省理工學(xué)院的第一臺數(shù)控展示機床在概念上幾乎沒有什么不同。 如果在概念中有較大的不同的話，那就是 CNC不再只是適用于旋轉(zhuǎn)/切削刀具對零件原料切除的加工。它能用于任何在機床刀具運

40、動平臺上進行的加工，而且其另一優(yōu)勢是使編程從機器操作中分離開來，也就是來自CAD/CAM技術(shù)。這些技術(shù)包括發(fā)射激光、焊接、摩擦焊接、超聲波焊接、氣割、彎曲、旋壓、釘壓、膠粘、簾布裁斷、縫合、帶和光纖放置、 造模銑切、分揀放置（PnP）、鋸割以及毫無疑問的未來工業(yè)加工方法。,Passage Two Electric Discharge Machining,2,Metal removal in electric discharge machining（EDM） is due to metal erosion by interrupted electrical discharges. The pro

41、cess is carried out in a dielectric medium（generally kerosene）. The EDM process is particularly advantageous in machining highly complicated shapes in forging， blanking， trimming， and other types of dies， and in machining hard and brittle materials. The major advantage of the process is that machini

42、ng can be carried out in the hardened state of the work materials， thus eliminating heat treating and the possibility of subsequent cracking.,Unit Four Manufacturing Technology of Mold,1.Principle of EDM machine,Unit Four Manufacturing Technology of Mold,The basic principle of the working of an EDM

43、machine is shown in Fig.4 -3. The main components of the machine are the worktable， tool holder， precision slides for tool holder in the two horizontal directions（ X and Y）， dielectric tank， pulse generating system， a d.c. power supply and a filter for refining of used dielectric. The work is connec

44、ted to the positive terminal（ anode） and the tool is made the cathode . The simplest circuit con- sists of a condenser and charging resistance（ RC circuit）. The tool end is brought near the work piece surface by a ser-vomotor . As the two get very near， the dielectric gives way and a discharge takes

45、 place between the nearest points on the,Unit Four Manufacturing Technology of Mold,Fig.4 -3 Schematic diagram of electric discharge machining 1filter; 2pump; 3electrolyte; 4dielectric tank; 5tool holder; 6gear box; 7servomotor; 8tool; 9overflow lube;10workpiece;11table;12vibrator for table,Unit Fou

46、r Manufacturing Technology of Mold,tool and the work piece surfaces. The condenser discharges and because of the charging resistance，the voltage across the tool and the work piece drops， and hence the discharge also stops. This sudden pulse of high intensity discharge can give rise to very high temp

47、eratures and possibly shock waves in the vicinity of the spark . The surface layer in line with the spark generally melts and is removed from the site by the pressure wave and cavitations . Thus both the tool and work piece surfaces wear out.,2.Pulse Generation Circuit,Unit Four Manufacturing Techno

48、logy of Mold,If the pulses are generated by an electronic circuit with or without a feed back， some of the disadvantages associated with the relaxation circuit can be removed. Relaxation circuits operate at high energy levels with lower frequencies of sparks. This is because with higher energy level

49、s， it takes more time for deionization and hence there is greater danger of arcing. Pulse circuits， on the other hand， can have higher frequencies. For the same machining rate， a lower energy per spark would be needed. Hence the spark path gets deionized quickly and the ratio of machining time to cy

50、cle time increases. The pulse circuit machines consume two to three times less energy and also result in reduced tool wear.,Unit Four Manufacturing Technology of Mold,3.Tool Materials,The major advantage of the EDM process is that tools of softer material can be used to erode very hard and brittle m

51、aterials. The tool materials generally used are copper， brass， aluminum， graphite， etc. Silver -tungsten and copper - tungsten are low wearing tool materials， which may be used for finish machining. Cast iron can also be used during rough machining.,4.Applications,The process can be used economicall

52、y for the following applications on workpieces， which are good conductors of electricity.,Unit Four Manufacturing Technology of Mold,（1）For machining dies for forging， blanking， extru- sion， etc.; （2）For drilling fine deep holes such as in fuel injector nozzles ; （3）For machining hydraulic valve spo

53、ols; （4）For slitting of hard alloys; （5） For manufacture of fragile components， which cannot be machined by conventional processes due to high tool forces.,5.Advantage of EDM,Electric discharge machining has many advantages over conventional machining processes:,Unit Four Manufacturing Technology of

54、 Mold,（1）Any material that is electrically conductive can be cut， regardless of its hardness. It is especially valuable for cemented carbides and the new super tough space -age alloys that are extremely difficult to cut by conventional means. （2）Workpiece can be machined in a hardened state， thereby

55、 overcoming the deformation caused by the hardening process. （3）Broken taps or drills can readily be removed from workpieces. （4）It does not create stresses in the work material since the tool（electrode） never comes in contact with the work. （5）The process is burr -free . （6）Thin， fragile sections c

56、an be easily machined with- out deforming .,Unit Four Manufacturing Technology of Mold,（7）Secondary finishing operations are generally elimi- nated for many types of work. （8）The process is automatic in that the servomechanism advances the electrode into the work as the metal is re- moved. （9）One pe

57、rson can operate several EDM machines at one time. （10） Intricate shapes， impossible to produce by conven- tional means， are cut out of a solid with relative ease. （11）Better dies and molds can be produced at lower costs. （12）A die punch can be used as the electrode to repro- duce its shape in the m

58、atching die plate， completed with the necessary clearance.,Unit Four Manufacturing Technology of Mold, As the two get very near， the dielectric gives way and a discharge takes place between the nearest points on the tool and the work piece surfaces. 當(dāng)兩者靠得很近時，介質(zhì)不再絕緣，在工具和工件表面的最近點產(chǎn)生一次放電。 “take place”譯為

59、“發(fā)生，產(chǎn)生”。 If the pulses are generated by an electronic circuit with or without a feed back， some of the disadvantages associated with the relaxation circuit can be removed. 如果通過帶或不帶反饋的電子電路來產(chǎn)生脈沖，可以克服與放電電路有關(guān)的一些缺點。 be associated with .是“與有關(guān)”的意思。 For manufacture of fragile components， which cannot be machined by conventional processes due to high tool forces. 用于加工易碎零件，這些零件因高應(yīng)力而不能用傳統(tǒng)方法加工。,Notes:,New Words and Expressions ：,Unit Four Manufacturing Technology of Mold,electric discharge machining（EDM）電火花加工 dischargedis t d n.放電，排放 erosioni r