計算機輔助設(shè)計外文翻譯---cadcam的應(yīng)用范圍

1、<p><b>　　附 錄</b></p><p><b>　　1 英文原文</b></p><p>　　Scope of CAD/CAM</p><p>　　Computer-aided design is the use of computer systems to facilitate the creat

2、ion, modification, analySIS, and optimization of a design. In this context the term computer system means a combination of hardware and software. Computer-aided manufacturing is the use of a computer system to plan, ma

3、nage, and control the opemtion of a manufacturing plant. An appreciation of the scope of CAD/CAM can be obtained by considering the stages that must be completed in the design and manufacture of a produc</p><

4、p>　　Based on market and customer requirements, a product is conceived, which may well be a modification of previous products. This product is then designed in detail, including any required design analysis, and drawi

5、ngs and parts lists are prepared. Subsequently, the various components and assemblies are planned for production, which involves the selection of sequences of processes and machine tools and the estimation of cycle times

6、, together with the determination of process parameters, such as fe</p><p>　　Computer-based procedures have been or are being developed to facilitate each of these stages in the product cycle, and these are

7、shown in the outer loop of Fig. 5 . 8. Computer-aided design and drafting techniques have been developed. These allow a geometric model of the product and its components to be created in the computer. This model can tlIe

8、n be analyzed using specialized software packages, such as those for finite element stress analysis, mechanisms design, and so on. Subsequently, dmwin</p><p>　　r'or scheduling and production control, lar

9、ge amounts of data and numerous relatively simple calculations must be carried out. One example is the determination of order quantities by subtmcting stock levels from forecasts of the number of items required during

10、a particular manufacturing period®. Many commercial software packages are available for scheduling, inventory control, and shop floor control, including materials requirements planning (MRP) systems. At the shop-

11、floor level computers </p><p>　　There is a difference in the time scale required for processing data and the issuing of instructions for these various applications of computers in the product cycle. For exam

12、ple, design and process-planning functions are carried out once for each new product and the time scale required is on the order of weeks to years for the competion of the task . Scheduling and production period cusuall

13、y one week,throughout the year .at the machine-control level in-structions must be issued continually wit</p><p>　　One of the major objectives of CAM is the integration of the various activities in the produ

14、ct cycle into one unified system, in which data is transfened from one function to another automatically. This leads to the</p><p>　　concept of computer-integrated manufacture ( CIM), with the final objecti

15、ve being the "paperless" factory. Several developments have taken place, but no totally integrated CIM systems have yet been achieved. Since the design and process-planning functions are carned out once in the

16、product cycle, these are the most suitable functions for integration. This integration is particularly desirable because the geometric data generated during the design process is one of the basic inputs used by proces<

17、;/p><p>　　1 Computer-Aided Design</p><p>　　Computer-aided design, or CAD as it is more commonly known, has grown from a narrow activity and conceI;>t to a methodology of design activities that i

18、nclude a computer or group of computers used to assist in the analysis, development, and draw-ing of product components. The original CAD systems developed and used in industry could more realistically be classified as

19、computer-aided drafting systems. However, the benefits, of using basic geometric information for structural analysis and planning</p><p>　　In general, there are four basic reasons for implementing CAD system

20、s. </p><p>　　1 . A reduction in design time. The total time required from inception of an idea to its complete specification can be reduced by an order of magnitude by using easily alterable geometric model

21、s. Design perturbations/ changes can be completed in minimal time. Whole scenarios of design possibilities can be constructed quickly. </p><p>　　2. Improved product design. Because CAD systems allow the des

22、igner to alter the product without major redrav-ring with considerable time commitment, many final designs can be constructed in a reasonable period of time. Similarly, these designs can be automatically analyzed for st

23、lUCtural characteristics by using computer-aided engineering (CAE) software such as finite-element modeling (FEM) . </p><p>　　3 . Improved information access. Because CAD drawings are stored in a large compu

24、ter database, they can be accessed quickly and easily. Parts can be coded on the basis of geometric shape, and similar parts can be called up to assist in the design and specification of new parts. "Standard parts&q

25、uot; can be employed whenever possible, rather than having to re-invent the wheel over and again. </p><p>　　4. Manufacturing, data creation. With the advent of numerical control (NC) carne the need to auto

26、matically generate the tool path required for machining. Since the part geometry dictates the machining required, kno,,-ing the part shape can allow for (semi-)automatic part-prograrn preparation. CAD data can also be u

27、sed for automated process planning. </p><p>　　It is interesting to note that twenty years ago if a part of reasonable geometric and manufacturing sophistication was created, hundreds of design and drafting

28、hours would be required. After the part was specified, marlufacture would begin. ll1is planning would normally require some minor design changes (back to the designer and draftsman), and might take as long as the origina

29、l design process. Special tooling, fixturing, etc., might also be specified during the plarming for manufacture. In all</p><p>　　paIt programs and producing the pm is possible in days rather than weeks. In g

30、eneral, the tatal en!?ineering aI1d manufacturing time has been markedly using integrated CAD/CAM methodalogies. </p><p>　　2 Computer- Aided lVIanufacturing </p><p>　　The scientific study of me

31、tal-cutting and autamatian techniques are pnxlucts af the twentieth century. Two. pianeers of these techniques were Frederick Taylar and Henry Ford. During tl1e early 1900s, the improving U. S. standard af living brough

32、t a new high in penlOnal wealth. 'Ille majar result wa<; the increased demand far durable goods. This increased demand meant that manufacturing cauld no. longer be treated as a blacksmith trade, aIld the use af s

33、cientific study was emplayed in manufactu</p><p>　　Henry Ford's contributions took a different turn from Taylor's. Ford refined and developed the use of assembly lines for the major component manufac

34、turer of his automobile. Ford felt that every American family sh~d have an automobile, and if they could be manufactured inexpensively enough then every family would buy one. Several mechanisms were developed at Ford to

35、accommodate assembly lines. The automation that Ford developed was built into the hardware, and Ford realized that significant deman</p><p>　　Although manufacturing industries continued to evolve, it was not

36、 until the 1950s that the next major development occurred. For some time, strides to reduce human involvement in manufacturing were being taken. Speciality machines using carns and other "hardwired" logic contr

37、ollers had been developed. The U. S. Air Force recognized the development time required to produce this special equipment and that the time required to make only small sequence changes was excessive. As a result, the Air

38、 Forc</p><p>　　It is interesting to note that much of the evolution in manufacturing has come. as a response to particular changes during different periods. For instance, the technology that evolved in the

39、nineteenth century brought with it the need for higher-precision machining (This resulted in the creation of many new machine tool;a more refined machine design, and new production processes. ). The early twentieth cent

40、ury became an era of prosperity and industrialization that created the demand necessary </p><p>　　A few tangential notes on this history include the following. As the volume of parts manufactured increases,

41、 the production cost for the parts decrease (this is generally known as "economy of scale"). Some of the change in production cost is due to fixed versus variable costs. For instance, if only a single part is t

42、o be produced (such as a space vehicle), all of the fixed costs for planning and design (both product and process) must be absorbed by the single item. If, however, several parts ar</p><p>　　The U. S. Depart

43、ment of Commerce has pointed out that in the United States, 95 % of all products are produced in lots of size 50 or fewer. This indicates that although high-volume techniques are desirable from a consumer standpoint (low

44、er cost), these techniques are not appopriate from a manufacturing standpoint (lower cost); the reason being the volume will not offset the setup expenses. The manufacturing alternative t6 produce those parts is throug

45、h the use of flexible manufacturing systems </p><p><b>　　中文翻譯</b></p><p>　　CAD/CAM的應(yīng)用范圍</p><p>　　計算機輔助設(shè)計是利用計算機系統(tǒng)對某項設(shè)計進行創(chuàng)造、修改、分析、和優(yōu)化。本文中的計算機系統(tǒng)是指計算機的硬件和軟件的組合、計算機輔助制造是利用計算機

46、系統(tǒng)來規(guī)劃、管理和控制制造廠的加工過程。根據(jù)產(chǎn)民設(shè)計和制造過程所必須完成的各項內(nèi)容，我們來描述CAD/CAM的作用范圍。</p><p>　　根據(jù)市場的需求來規(guī)劃產(chǎn)品，很可能就是對原產(chǎn)品進行改進，然后再具體設(shè)計產(chǎn)品，包括進行具體必要的分析，畫出零件圖和編寫零件說明表，其次要對各個零部件的生產(chǎn)作出規(guī)劃，其中包括確定加工順序，選擇機床及估算產(chǎn)生產(chǎn)周期，確定工藝參數(shù)。當產(chǎn)品投入生產(chǎn)后，安排生產(chǎn)時間，控制生產(chǎn)，確定加工和

47、裝配每個零件中每個環(huán)節(jié)的先后順序和所需要的時間，使之符合總體的生產(chǎn)進度安排，然后根據(jù)此安排進行實際生產(chǎn)和產(chǎn)品質(zhì)量控制，最后將成品交付給用戶。</p><p>　　我們已經(jīng)或正在使用計算機技術(shù)來完成產(chǎn)品在生產(chǎn)過程中的各個環(huán)節(jié)的工作，我們已經(jīng)研制成了計算機輔助設(shè)計和計算機繪圖技術(shù)，利用這些技術(shù)就能在計算機上生成產(chǎn)品及其零件的模型。然后通過各種專用軟件來分析該模型。其次，用計算機輔助繪圖軟件和繪圖機繪制零件及明細表。包

48、括編制數(shù)控程序的功能和計算機輔助工藝設(shè)計系統(tǒng)，可根據(jù)零件的幾何參數(shù)和裝配要求自動編制出作業(yè)計劃，進行計算和生成加工指令。</p><p>　　要作出計劃和生產(chǎn)控制，需要獲取大量數(shù)據(jù)，進行許多比較簡單的計算。例如，將某 一生產(chǎn)周期所需物料預測數(shù)量減去庫存量，便可確定該物料的定貨量，許多喊有物料需求計劃（MRP）系統(tǒng)軟件包可用于制訂作業(yè)計劃，控制庫存量以及車間生產(chǎn)控制。車間底層應(yīng)用的計算機廣泛用于控制和監(jiān)測機床。&l

49、t;/p><p>　　為生產(chǎn)過程中各種計算機的應(yīng)用處理數(shù)據(jù)、生成指令所需的時間長短不同。例如，要對沒一種新產(chǎn)品進行設(shè)計并編制工藝規(guī)程，整個時間為幾周到數(shù)年。作業(yè)計劃和生產(chǎn)過程控制在全年的每個生產(chǎn)周期內(nèi)重復一次（通常每周一次）。而機床控制指令必須連續(xù)不斷的加以處理，許多情況下其處理的時間僅為幾微秒或幾納秒。</p><p>　　CAM的主要目標之一是將生產(chǎn)過程中的各種活動集成一個同一的系統(tǒng)，此系

50、統(tǒng)中不同功能模塊間可自動傳送數(shù)據(jù)。這就引出了計算機集成制造這一概念，其最終目標就是無紙化工廠，在這方面已經(jīng)取得了許多成就但完全集成的CIM系統(tǒng)還沒有研制成功，由于產(chǎn)品設(shè)計和工藝規(guī)程設(shè)計在產(chǎn)平生產(chǎn)周期內(nèi)只進行一次，所以他們最適合于集成。這種集成特別需要，因為設(shè)計過程生成的幾何參數(shù)是在指定合適的制造過程和作業(yè)計劃時確定工藝過程所需要的基本設(shè)備之一。所以，產(chǎn)品設(shè)計和工藝規(guī)程設(shè)計可共享一個通用的設(shè)計只在數(shù)據(jù)庫，利用這樣的系統(tǒng)在設(shè)計過程中可生成產(chǎn)

51、品的模型，詞數(shù)據(jù)然后用于各個生產(chǎn)控制管理環(huán)節(jié)，包括編制NC程序、工藝規(guī)程及編制機器人程序，由這些活動所生成的程序和作業(yè)計劃進行訪問，估算時間定額并列出零件明細表（材料文件清單。</p><p>　　具有計算機輔助制造功能的產(chǎn)品設(shè)計周期</p><p>　　計算機輔助設(shè)計及計算機繪圖及自動打開文件；基本的產(chǎn)品生產(chǎn)周期；產(chǎn)品的構(gòu)思；繪圖，擁護及市場要求；訂購新設(shè)備及工藝裝備；工藝過程設(shè)計；計算

52、機輔助工藝設(shè)計；質(zhì)量控制；生產(chǎn)；作業(yè)計劃；每個產(chǎn)品的生產(chǎn)周期為幾周至數(shù)年；計算機輔助質(zhì)量控制；計算機控制機器人；機械設(shè)備等；計算機制定作業(yè)計劃。</p><p>　　集成設(shè)計與制造數(shù)據(jù)庫</p><p>　　CAD；CAM；幾何建模；編制數(shù)控加工程序；分析；編制機器人程序；人機交互式工作站；集成數(shù)據(jù)庫；自動輸出參數(shù)；運動分析；工藝編程；自動繪圖；工廠管理。</p><p

53、><b>　　計算機輔助設(shè)計</b></p><p>　　計算機輔助設(shè)計又稱為CAD，廣為人知，已經(jīng)從一種范圍狹小的范圍活動和概念成為設(shè)計方法學，他使用一臺或一組計算機來幫助人們對產(chǎn)品，零件進行分析、設(shè)計和繪圖。更切實的說，工業(yè)上最早研制和使用的CAD系統(tǒng)應(yīng)屬于計算機輔助繪圖系統(tǒng)。然而，人們很快認識到了用基本幾何信息來進行結(jié)構(gòu)分析和確定加工方案的優(yōu)越性，并在許多CAD系統(tǒng)中加入了這些內(nèi)

54、容?，F(xiàn)在和過去一樣，CAD的基礎(chǔ)仍是圖形特征或交互式圖形特征系統(tǒng)，而這些系統(tǒng)最初也就是用來完成這些功能。但是CAD系統(tǒng)已經(jīng)有了新的含義。</p><p>　　總的來說，CAD系統(tǒng)有四個基本理由</p><p>　　減少設(shè)計時間。由于使用容易交換的幾何模型進行設(shè)計，可將從構(gòu)思設(shè)計到完成產(chǎn)品說明書所須的設(shè)計總的時間減少一個數(shù)量級?？捎脮r間最少時間完成設(shè)計的變更。能夠很快制定出所有的可能的設(shè)計方

55、案。</p><p>　　提高設(shè)計水平。因為CAD系統(tǒng)能使設(shè)計者有很多時間來改進產(chǎn)品而無需大量的重新繪圖，因此能在，能在合理的時間內(nèi)設(shè)計初最終產(chǎn)品。同樣，使用計算機輔助工程軟件，如有限元模型便可自動地分析設(shè)計機構(gòu)特征。</p><p>　　改進了信息的存取方法。因為CAD圖形存儲在大型計算機數(shù)據(jù)庫中，所以可迅速而方便的存取?？梢栽趲缀涡螤畹幕A(chǔ)上對零件的編碼，能夠調(diào)用類似的零件來設(shè)計和規(guī)范

56、新的零件。應(yīng)盡可能地采用標準零件，而不是重復設(shè)計同類零件。</p><p>　　創(chuàng)成制造信息資料。隨著數(shù)控技術(shù)的出現(xiàn)，需要能自動生成加工林所須的刀具路徑。由于零件的幾何圖形反映了加工要求，所以制造了零件形狀就能自動或半、自動的編制零件程序。CAD數(shù)據(jù)也可用于工藝規(guī)程的自動設(shè)計。</p><p>　　有趣的是，在二十年前如果要設(shè)計出幾何形狀合理的零件并制訂出先進的加工方案，需要幾百小時的設(shè)計

57、和繪圖時間。所設(shè)計的零件被確定之后便開始生產(chǎn)，通常往往要對此設(shè)計進行小小的更改，還可能花費與設(shè)計相當?shù)臅r間。確定加工方案的過程中，也可能要設(shè)計專用的工藝裝備，夾具等?？偟膩碚f，整個產(chǎn)品設(shè)計過程和工藝過程制定可能花費幾周或幾個月的時間。利用當今的CAD系統(tǒng)，設(shè)計產(chǎn)品和制訂加工方案，編制零件程序及加工出零件可能只需幾天而不是幾周時間。總之，整個工程和制造時代是以使用集成的CAD/CAM方法為標志的。</p><p>

58、<b>　　計算機輔助制造</b></p><p>　　金屬切削和自動化技術(shù)的科學研究是二十世紀的產(chǎn)物。研究這些技術(shù)的兩大任務(wù)是福拉狄采克.泰勒和亨利福特。二十世紀初期，美國人民生活水平提高，增加了個人財富，從而又導致了人們對耐用品的需求增多。需求的增多也就以為著再也不能視制造業(yè)為鐵匠行業(yè)，要采用科學來分析制造工程。泰勒倡導了“科學管理”的研究，研究了包含人和機床的生產(chǎn)方法。他還在NIDVA

59、LE鋼鐵公司進行了長達26年之久的金屬切削實驗，產(chǎn)生400噸金屬切屑。泰勒金屬切屑的實驗結(jié)果的出了至今仍在使用的泰勒刀具耐用度方程，該方程仍是選擇經(jīng)濟的金屬切削方法的依據(jù)并已用于自適應(yīng)控制加工。</p><p>　　亨利.福特所做的貢獻與泰勒的有所不同，福特為其汽車主要零件制造廠研制并改進了裝類生產(chǎn)線。福特認為每個美國家庭都應(yīng)該有一輛汽車，如果汽車生產(chǎn)成本足夠低的話，那么每個家庭都可以購買，福特研制成了一些裝配裝

60、置來適應(yīng)裝配生產(chǎn)線的要求。福特研制成的自動裝置制成了硬件，他也意識到要補償最初研制和生產(chǎn)這種系統(tǒng)的費用，產(chǎn)品的需求量必須大。</p><p>　　盡管制造業(yè)持續(xù)發(fā)展，但直到20世紀50年代才出現(xiàn)了第二次重大進展。一段時間曾在減少加工過程中人工干預方面取得了很大的進步，研制成功了使用凸輪和其他硬件的邏輯控制器的專用機床。美國空軍認識到生產(chǎn)這些專用設(shè)備所需要的時間以及只對加工順序作小的邊動所需要的時間都過大。所以美國

61、空軍委托MIT論證了可編程和數(shù)字控制NC機床。隨著1952年NC機床的首次演示開始了制造的新紀元。此后，數(shù)字計算機被應(yīng)用直接對許多數(shù)控機床產(chǎn)生輸入直接數(shù)字控制，對具有更加專用控制的計算機數(shù)字控制產(chǎn)生輸入。</p><p>　　當今各種機床控制語言，如APT（自動編程工具），都已成為NC機床對刀具進行控制的標準語言。</p><p>　　有趣的是，隨著不同時期發(fā)生的待定變化，制造工業(yè)取得了很

62、大進展。例如19世紀的技術(shù)進步帶來了高精加工的要求（由此發(fā)明了很多新機床，機床設(shè)計的更合理，并形成了一些新的加工方法）。20世紀初期是一個繁榮的工業(yè)化時代，需要進行大量的生產(chǎn)技術(shù)。在20世紀50年代，人們估計，隨著飛機飛速的提高，飛機的再造成本將成比例的增加（因為飛機的幾何形狀復雜性提高），這就導致NC技術(shù)的發(fā)展。</p><p>　　上述歷史的幾點粗淺的啟示如下。隨著零件加工數(shù)量的增加，零件的生產(chǎn)成本的降低。生

63、產(chǎn)成本的一些變化是由于固定成本相對于可變成本的比值變化。例如，如果只生產(chǎn)一樣產(chǎn)品（如太空飛行器），所有的計劃和設(shè)計所需的全部成本只有該產(chǎn)品承擔。然而，如果生產(chǎn)幾件產(chǎn)品，那么這些固定費用就可用幾件產(chǎn)品分攤。生產(chǎn)成本的變化并不是由這種固定成本與可變成本簡單關(guān)系反映出來的，而通常取決于不同的制造技術(shù)，即大批量生產(chǎn)的自動線技術(shù)及小批量生產(chǎn)的車間生產(chǎn)技術(shù)。</p><p>　　美國商業(yè)部指出，在美國有95%的產(chǎn)品的生產(chǎn)批量

64、為50件或者更少，這就表明雖然從消費者的立場來看需要大量的生產(chǎn)技術(shù)，但從制造廠的觀點來看，這些技術(shù)是不合適的；原因在于這種批量補償不了調(diào)整費用。制造廠應(yīng)選擇柔性制造系統(tǒng)（FMS）生產(chǎn)這些產(chǎn)品，這些系統(tǒng)無非就是可編程序的加工車間。然而，在開始充分利用這種系統(tǒng)只前，仍存在著經(jīng)性這一主要問題。其障礙就是仍要花費很多的調(diào)整費用。應(yīng)應(yīng)用計算機輔助設(shè)計和計算機輔助制造集成（CAD/CAM）可以克服調(diào)整費用高的問題。CAD/CAM集成系統(tǒng)中，采用CA