外文翻譯--成組技術

1、<p>　　Group Technology</p><p>　　Group technology (GT) is a very important methodology in today’s manufacturing significant. The reason for this is that group technology, when utilized to its fullest ext

2、ent, can affect most areas of manufacturing, including design, process planning, scheduling, routing, factory layout, procurement, quality assurance, machine tool utilization, tool design, producibility engineering, and

3、assembly.</p><p>　　1 Introduction</p><p>　　Group technology is a simple concept that is used widely in various forms. For a variety of reasons, it is logical to collect and associate things base

4、d on features that they have in common. This approach is familiar to everyone for plants, animals, and chemicals. Such organizational structures have also been used for hardware and other obviously similar products withi

5、n the manufacturing world. Group technology represents structured categorization of particular value to the manufacturing communi</p><p>　　Bath or lot production suffers from many inefficiencies due to part

6、variety and the general-purpose nature (flexibility requirements) of machine tools in use on the shop floor. In fact, a Cincinnati Milacron study showed that 95% of the time a part spends on the shop floor is idle time,

7、the other 5% is divided between setup and teardown of the machine tool. The future breakdown of the 5% of on-machine time was developed by Dunlap. Based on this estimate, only 24% of the 5% is time which actually</p&g

8、t;<p>　　2 Definition</p><p>　　Manufacturing philosophy to some, fundamental building block for more efficient production to most, group technology is a simple concept which utilizes/exploits similarit

9、ies for more efficient production in bath manufacturing. Group technology usually classifies parts in the form of a code which is assigned to each part based on its shape or production processing characteristics. In use,

10、 coding parts assists in the control of planning and processing. This added control, which exploits similariti</p><p>　　3 General Benefits</p><p>　　In practice, group technology is really nothin

11、g more than an information/indexing system. However, because of its focus on part design and processing similarities, analysis is possible which creates manufacturing economies of scale, encourages standardization, and e

12、liminates duplication in design and process planning.</p><p>　　Mass production enjoys the benefits of what are called economies of scale. Economies of scale achieved by processing a large number of parts ove

13、r the same workstations or equipment. This result in less labor per part, more efficient machine utilization, and a faster turnover of inventory. Batch production in the past has not enjoyed economies of scale because of

14、 the need to remain flexible for changing part types and products. However, by grouping parts into families based on their similarities,</p><p>　　Standardization is achieved in both design and part process p

15、lanning. Essentially, group technology creates an efficient design retrieval system since parts have been code based on shape. Similar design are located quickly and aspects such as part tolerances and producibility can

16、be better understood, more easily applied, and kept more consistent from design to design. When standardized process planes are developed and include in the group technology code, new parts and repeat orders can follow &

17、lt;/p><p>　　Group technology eliminates duplication. In both design and process planning, there is much les “reinventing of the wheel” since there is sufficient retrieval of standard designs and process plans.&

18、lt;/p><p>　　4 Application of GT in Process Planning</p><p>　　Although many areas of business operation can benefit from GT, manufacturing, the original application area, continues to be the place w

19、here GT is most widely practiced. Two important tasks in manufacturing planning and manufacturing engineering are scheduling and process planning. Job scheduling sets the order in which parts should be processed and can

20、determine expected completion times for operation and orders. Process planning, on the other hand, decides the sequence of machines to which a p</p><p>　　Some of the largest productivity gains have been repo

21、rted in the creation of process plans that determine how a part should be produced. With computer-aided process planning (CAPP) and GT it is possible to standardize such plans, reduce the number of new ones, and store, r

22、etrieve, edit, and print them out very efficiently.</p><p>　　Process planning normally is not a formal procedure. Each time a new part is designed, a process planner will look at the drawing and decide which

23、 machine tools should process the parts, which operations should be performed, and in what sequence </p><p>　　There are two reasons why companies often generate excess process plans. First, most companies ha

24、ve several planners, and each may come up with a different process plan for the very same part, Second, process; planning is developed with the existing configuration of machine tools in mind. Over time, the addition of

25、new equipment will change the suitability of existing plans. Rarely are alterations to old process plans made. One company reportedly had 477 process plans developed for 523 different</p><p>　　Process planni

26、ng with CAPP takes two different forms;</p><p>　　With variant-based planning, one standardized plan (and possibly one or more alternate plans) is created and stored for each part family. When the planner ent

27、ers the GT code for a part, the computer will retrieve the best process plan. If none exists, the computer will search for routings and operations for similar parts. The planner can edit the scheme on the CRT screen befo

28、re printout.</p><p>　　With generative planning, which can but does not necessarily rely on coded and classified parts, the computer forms the process plan through a series of questions the computer poses on

29、the screen. The end product is also a standardized process plan, which is the best plan for a particular part.</p><p>　　The variant-based approach relied on established plans entered into the computer memory

30、, while the generative technique creates the process plans interactively, relying on the same logic and knowledge that a planner has. Generative process planning is much more complex than variant-based planning; in fact,

31、 it approaches the art of artificial intelligence. It is also much more flexible; by simply changing the planning logic, for instance, engineers can consider the acquisition of a new machine to</p><p>　　CAPP

32、 permits creation and documentation of process plans in a fraction of the time it would take a planner to do the work manually and vastly reduces the number of errors and the number of new plans that must be stored. When

33、 you consider that plans normally are handwritten and that process planners spend as much as 30% of their time preparing them, CAPP’S contribution of standardized formats for plans and more readable documents is importan

34、t. CAPP, in effect, functions as advanced text editor. F</p><p>　　CAPP can lead to lower unit costs through production of parts in an optimal way. That is, cost savings come not only via more efficient proce

35、ss planning but also through reduced labor, material, tooling, and inventory costs.</p><p>　　GT can help in the creation of programs that operate numerically (NC) machinery, n area related to process plannin

36、g. For example, after the engineers at Otis Engineering had formed part families and cells, the time to produce a new NC tape dropped from between 4 and 8 hours to 30 minutes. The company thereby improved the potential f

37、or use of NC equipment on batches with small manufacturing quantities.</p><p><b>　　編者：吳非曉等</b></p><p><b>　　《機械英語2》</b></p><p>　　外語教學與研究出版社 2002.7</p>

38、<p><b>　　成組技術</b></p><p>　　在當今的制造環(huán)境下，尤其是對批量生產(chǎn)來說，成組技術（GT）是一個很重要的生產(chǎn)方式而且它正變得越來越重要。其原因在于，當成組技術發(fā)揮最大作用的時候，能夠影響大多數(shù)的制造領域，其中包括設計、工藝規(guī)劃、調度、路線、工廠布局、采購、質量保證、車床應用、刀具設計、生產(chǎn)能力設計及組裝。</p><p><

39、b>　　1 簡介</b></p><p>　　成組技術是一個以各種形式廣泛應用的簡單概念。基于各種原因，我們有理由根據(jù)事物的共同特征把它們收集并聯(lián)系在一起。對于植物、動物和化合物來說，每個人都很熟悉這種方法。在制造業(yè)內，這種組織結構也被用于硬件和其它明顯相似的產(chǎn)品中。成組技術對于生產(chǎn)團體來說，代表著具有具體價值的組織分類。它早就被廣泛應用，大約有50%的生產(chǎn)企業(yè)在使用某種形式的成組技術。<

40、/p><p>　　由于零件多種多樣以及生產(chǎn)車間使用的車床的通用特性（靈活性要求），造成了批量和規(guī)模生產(chǎn)效率差的情況很多。一份辛辛那提麥爾克倫的研究表明，實際上一個零件花費在生產(chǎn)車間的時間有95%是閑置的，另外5%的時間在車床的裝配和拆卸之間進行分配。Dunlap對這5%的機上時間進一步的分解進行了研究。據(jù)此估計，5%的機上時間中只有24%的時間用于切割。也就是說，只有1.2%的總時間用于零部件的加工。成組技術能夠利用

41、幾中不同分析的方法，通過零件族來減少零件的種類，從而使批量生產(chǎn)更具有效率，提高生產(chǎn)能力并緩解加工過程的庫存問題。正是由于這個原因，成組技術才在生產(chǎn)中成為一個至關重要的概念。</p><p><b>　　2 定義</b></p><p>　　成組技術在某種程度上是一種生產(chǎn)觀念，而在很大程度上是高效率生產(chǎn)的基本構件，它是一個簡單的概念，它在批量生產(chǎn)過程中利用或使用相似性提

42、高制造效率。成組技術通常利用代碼將零件分類。代碼是根據(jù)零件的形狀或生產(chǎn)過程的特征分配給每個零件的。使用中，代碼零件有助于對規(guī)劃和加工的控制。這種利用相似性的附加控制能給整個生產(chǎn)過程帶來許多經(jīng)濟效益。車間里的實際操作者可能永遠也不知道這個代碼，但是設計者、工程師和規(guī)劃人員把它當成一種最寶貴的工具，能夠使他們進行更加有用和富有成效的分析。</p><p><b>　　3 益處</b></p

43、><p>　　實際上，成組技術其實就是一個信息或索引系統(tǒng)。然而，由于它著眼于零件設計和加工的相似性就有可能進行分析，規(guī)模生產(chǎn)的經(jīng)濟效益，促進標準化并避免重復設計和工藝規(guī)劃。</p><p>　　批量生產(chǎn)有利于規(guī)模經(jīng)濟。規(guī)模經(jīng)濟效益通過用同一車間或設備加工大量零件來實現(xiàn)。這意味著每個零件所用勞動力較少，機械利用率更高，庫存周轉更快。過去的批量生產(chǎn)并沒有獲得規(guī)模生產(chǎn)的經(jīng)濟效益，原因在于需要保持靈活

44、性來更換零件的種類和產(chǎn)品。然而，通過根據(jù)相似性對零件進行分組，在整個族內就可以完成這些零件的大部分生產(chǎn)加工。這就增加了同一個生產(chǎn)設備條件下加工零件的數(shù)量，因此就能帶來規(guī)模生產(chǎn)所追求的一些經(jīng)濟效益。</p><p>　　標準化是在設計和零件工藝規(guī)劃中完成的。重要的是，由于零件根據(jù)形狀被編碼，成組技術提供了一個有效率的設計檢索系統(tǒng)。相似的設計很快就能找到，一些諸如零件公差和可制造性問題得到了更好的解決，利用更方便，而

45、且從設計到設計都保持一致性。一旦制定了標準化的工藝規(guī)劃并被編入成組技術代碼中，新零件和重復命令就能通過生產(chǎn)車間在相似的加工路線上運行，簡化了車間的計劃和流程。</p><p>　　成組技術減少重復。在設計和加工計劃中只有較少的“操縱輪的重新設定”，因為有足夠的標準化的設計和工藝規(guī)程供檢索。</p><p>　　4 成組技術在工藝規(guī)劃中的應用</p><p>　　雖然

46、很多商業(yè)領域可以從成組技術中獲益，但是制造這一GT最初的應用領域仍然是GT最為廣泛實踐的地方。制造計劃與制造工程的兩個重要任務是調度和工藝規(guī)劃。作業(yè)調度安排零件所加工的流程，并可確定工序期望完成的時間和流程；在另一方面，工藝規(guī)劃決定了零件制造時所應發(fā)送的機器流程以及在每臺機器上所應完成的工序。工藝規(guī)劃還包括刀具、夾具和定位器的選擇以及有關每道工序的時間標準（運轉時間與準備時間）的文件編制。工藝規(guī)劃可以直接影響調度效率，從而很多工作指標通

47、常與制造計劃與制造控制有關。</p><p>　　據(jù)報道，提高生產(chǎn)率最主要的一些因素，是建立了工藝規(guī)程，該規(guī)程確定了應當如何制造一個零件。利用計算機輔助工藝規(guī)劃（CAPP）和成組技術，可能使這種計劃標準化、減少新計劃的數(shù)量，以及很有效地將它們存儲、恢復、編輯和打印。</p><p>　　工藝規(guī)劃通常不是一個正式程序。每當設計一個新零件時，工藝規(guī)劃人員就會看圖并確定用哪些機床加工這些零件、要

48、完成哪些工序以及用什么流程完成。</p><p>　　公司經(jīng)常會產(chǎn)生額外工藝規(guī)程的原因有兩個：首先，大多數(shù)公司都有幾個規(guī)劃人員，每個人對于相同的零件可能會拿出不同的工藝規(guī)程：其次，工藝規(guī)劃是利用頭腦中現(xiàn)有機床的配置得出的。隨著時間的推移，新裝備的增加會改變現(xiàn)有規(guī)程的適用性，而很少改變已制定的工藝規(guī)程。據(jù)說一家公司曾為523個不同齒輪開發(fā)了477個工藝規(guī)程。詳細研究表明超過400個規(guī)程可以取消。使用計算機輔助工藝規(guī)

49、劃可以避免這些問題。</p><p>　　利用計算機輔助工藝規(guī)劃進行工藝規(guī)劃時常采用2種不同形式：</p><p>　　利用基于變量的規(guī)劃時，為每個零件族建立和存儲一個標準規(guī)程（可能有一個或多個備選規(guī)程）。當規(guī)劃人員輸入一個零件的GT編碼時，計算機就會找到最佳的工藝規(guī)程。如果沒有工藝規(guī)程，計算機就會搜索相似零件的工序以及工序流程。規(guī)劃人員可以在打印輸出前在CRT屏幕上編輯這個規(guī)程。<

50、/p><p>　　利用生成規(guī)劃時，計算機通過一系列在計算機屏幕上提出的問題來形成工藝規(guī)程，生成規(guī)劃可以依靠但并非必須依靠編碼和分類的零件。最終產(chǎn)物也是一個標準的工藝規(guī)程，是適于一個特殊零件的最佳規(guī)程。</p><p>　　基于變量的方法是依靠輸入計算機內存中的已經(jīng)建立的規(guī)程，而生成技術交互地建立工藝規(guī)程，依靠規(guī)劃人員所具有的相同的邏輯和知識。生成的工藝規(guī)劃遠比基于變量的規(guī)劃復雜，事實上，它接近

51、人工智能的技巧。它也更加靈活，例如，通過簡單地改變規(guī)劃邏輯，工程師可以考慮得到一臺新機床。對于基于變量的方法，工程師必須檢查并會修改可能受新裝備影響的所有規(guī)程。</p><p>　　計算機輔助工藝規(guī)劃讓規(guī)劃人員以人工規(guī)程的一小部分時間來創(chuàng)建規(guī)程和編制文件，極大地減少了出錯的數(shù)量和必須存儲的新規(guī)程。當考慮到規(guī)程通常是手寫的且規(guī)劃人員要花30%的時間準備時，計算機輔助工藝規(guī)劃對于規(guī)程標準格式以及更加可讀的文件的貢獻就

52、很重要了。實際上，計算機輔助工藝規(guī)劃起到一個高級文本編輯器的作用。此外，它可以連接到計算和記錄每到工序的運行和準備時間的自動化的標準數(shù)據(jù)系統(tǒng)。</p><p>　　計算機輔助工藝規(guī)劃通過以最佳途徑生產(chǎn)零件，可以降低成本。也就是說，成本節(jié)約不僅能通過更為有效的工藝規(guī)劃來實現(xiàn)，而且通過減少人工、材料、工具以及庫存的成本來實現(xiàn)。</p><p>　　成組技術可以幫助建立操作數(shù)控機械的程序，一個與