外文翻譯--注塑模具自動裝配造型

1、<p>　　注塑模具自動裝配造型</p><p>　　X. G. Ye, J. Y. H. Fuh and K. S. Lee</p><p>　　機械和生產工程部，新加坡國立大學，新加坡</p><p>　　注射模是一種由與塑料制品有關的和與制品無關的零部件兩大部分組成的機械裝置。本文提出了（有關）注射模裝配造型的兩個主要觀點，即描述了在計算機上進行注射

2、模裝配以及確定裝配中與制品無關的零部件的方向和位置的方法，提出了一個基于特征和面向對象的表達式以描述注射模等級裝配關系，該論述要求并允許設計者除了考慮零部件的外觀形狀和位置外，還要明確知道什么部份最重要和為什么。因此，它為設計者進行裝配設計（DFA）提供了一個機會。同樣地，為了根據裝配狀態(tài)推斷出裝配體中裝配對象的結構，一種簡化的特征幾何學方法也誕生了。在提出的表達式和簡化特征幾何學的基礎上，進一步深入探討了自動裝配造型的方法。</

3、p><p>　　關鍵字：裝配造型；基于特征；注射模；面向對象。</p><p><b>　　1、簡介</b></p><p>　　注射成型是生產塑料模具產品最重要的工藝。需要用到的兩種裝備是：注射成型機和注射?！，F在常用的注射成型機即所謂的通用機，在一定尺寸范圍內，可以用于不同形狀的各種塑料模型中，但注射模的設計就必須隨塑料制品的變化而變化。模型的

4、幾何因素不同，它們的構造也就不同。注射模的主要任務是把塑料熔體制成塑料制品的最終形狀，這個過程是由型芯、型腔、鑲件、滑塊等與塑料制品有關的零部件完成的，它們是直接構成塑料件形狀及尺寸的各種零件，因此，這些零件稱為成型零件。（在下文，制品指塑料模具制品，部件指注射模的零部件。）除了注射成型外，注射模還必須完成分配熔體、冷卻，開模，傳輸、引導運動等任務，而完成這些任務的注射模組件在結構和形狀上往往都是相似的，它們的結構和形狀并不取決于塑料模

5、具，而是取決于塑料制品。圖1顯示了注射模的結構組成。</p><p>　　成型零件的設計從塑料制品中分離了出來。近幾年，CAD/CAM技術已經成功的應用到成型零件的設計上。成型零件的形狀的自動化生成也引起了很多研究者的興趣，不過很少有人在其上付諸實踐，雖然它也象結構零件一樣重要?，F在，模具工業(yè)在應用計算機輔助設計系統(tǒng)設計成型零件和注射成型機時，遇到了兩個主要困難。第一，在一個模具裝置中，通常都包括有一百多個成型零

6、部件，而這些零部件又相互聯系，相互限制。對于設計者來說，確定好這些零部件的正確位置是很費時間的。第二，在很多時候，模具設計者已想象出工件的真實形狀，例如螺絲，轉盤和銷釘，但是CAD系統(tǒng)只能用于另一種信息的操作。這就需要設計者將他們的想法轉化成CAD系統(tǒng)能接受的信息(例如線，面或者實體等)。因此，為了解決這兩個問題，很有必要發(fā)展一種用于注射模的自動裝配成型系統(tǒng)。在此篇文章里，主要講述了兩個觀點：即成型零部件和模具在計算機上的防真裝配以及確

7、定零部件在模具中的結構和位置。</p><p>　　這篇文章概括了關于注塑成型的相關研究，并對注射成型機有一個完整的闡述。通過舉例一個注射模的自動裝配造型，提出一種簡化的幾何學符號法，用于確定注射模具零部件的結構和位置。</p><p><b>　　2、相關研究</b></p><p>　　在各種領域的研究中，裝配造型已成為一門學科，就像運動學

8、、人工智能學、模擬幾何學一樣。Libardi作了一個關于裝配造型的調查。據稱，很多研究人員已經開始用圖表分析模型會議拓撲。在這個圖里，各個元件由節(jié)點組成的，再將這些點依次連接成線段。然而這些變化矩陣并沒有緊緊的連在一起，這將嚴重影響整體的結構，即，當其中某一部分移動了，其他部分并不能做出相應的移動。Lee and Gossard開發(fā)了一種新的系統(tǒng)，支持包含更多的關于零部件的基本信息的一種分級的裝配數據結構，就像在各元件間的“裝配特征”。

9、變化矩陣自動從實際的線段間的聯系得到，但是這個分級的拓撲模型只能有效地代表“部分”的關系。</p><p>　　自動判別裝配組件的結構意味著設計者可避免直接指定變化的矩陣，而且，當它的參考零部件的尺寸和位置被修改的時候，它的位置也將隨之改變。現在有三種技術可以推斷組件在模具中的位置和結構：反復數值技術,象征代數學技術，以及象征幾何學技術。Lee and Gossard提出一項從空間關系計算每個組成元件的位置和方向

10、的反復數值技術。他們的理論由三步組成：產生條件方程式，降低方程式數量，解答方程式。方程式有：16個滿足未知條件的方程式，18個滿足已知條件的方程式，6個滿足各個矩陣的方程式以及另外的兩個滿足旋轉元件的方程式。通常方程式的數量超過變量的數量時，應該想辦法去除多余的方程式。牛頓迭代法常用來解決這種方程式。不過這種方法存在兩種缺點：第一，它太依賴初始解；第二：反復的數值技術在解決空間內不能分清不同的根。因此，在一個完全的空間關系問題上，有可能

11、解出來的結果在數學理論上有效，但實際上卻是行不通的。</p><p>　　Ambler和Popplestone提議分別計算每個零部件的旋轉量和轉變量以確定它們之間的空間關系，而解出的每個零部件的6個變量(3個轉變量和3旋轉量)要和它們的空間關系一致。這種方法要求大量的編程和計算，才能用可解的形式重寫有關的方程式。此外，它不能保證每次都能求出結果，特別是當方程式不能被以可解答的形式重寫時。</p>&

12、lt;p>　　為了能確定出滿足一套幾何學限制條件的剛體的位置與方向，Kramer開發(fā)了一種特征幾何學方法。通過產生一連串滿足逐漸增長的限制條件的動作推斷其幾何特征，這樣將減少物體的自由度數。Kramer使用的基本參考實體稱為一個"標識"，由一個點和兩正交軸構成。標識間的7個限制條件（coincident, in-line, in-plane, parallelFz,offsetFz, offsetFx and

13、helical)都被定了義。對于一個包括獨立元件、相互約束的標識和不變的標識的問題來說，可以用動作分析法來解決問題，它將一步一步地最后求出物體的最終的幾何構造。在確定物體構造的每一個階段，自由度分析將決定什么動作能提供滿足限制物體未加限制部位的自由度。然后計算該動作怎樣能進一步降低物體的自由度數。在每個階段的最后，給隱喻的裝配計劃加上合適的一步。根據Shah和Rogers的分析，Kramer的理論代表了注射模具最顯著的發(fā)展，他的特征幾何

14、學方法能解出全部的限制條件。和反復的數值技術相比，他的這種方法更具吸引力。不過要實行這種方法，需要大量的編程。</p><p>　　現在雖然已有很多研究者開始研究注射成型機，但仍很少有學者將注意力放在注射模設計上。Kruth開發(fā)了一個注射模的設計支援系統(tǒng)。這個系統(tǒng)通過高級的模具對象(零部件和特征)支持注射模的成型設計。因為系統(tǒng)是在AUTOCAD的基礎上設計的，因此它只適于線和簡單的實體模型操作。</p>

15、;<p><b>　　3、注射模裝配概述</b></p><p>　　主要講述了關于注射模自動裝配造型的兩個方面：注射模在電腦上的防真裝配和確定結構零件在裝配中的位置和方向。在這個部分，我們基于特征和面向對象論述了注射模裝配。</p><p>　　注射模在電腦上的防真裝配包含著注射模零部件在結構上和空間上的聯系。這種防真必須支持所有給定零部件的裝配、在相

16、互關聯的零部件間進行變動以及整體上的操作。而且防真裝配也必須滿足設計者的下列要求：</p><p>　　1）支持能表達出模具設計者實體造型想象的高級對象。</p><p>　　2）成型防真應該有象現實一樣的操作功能，就如裝入和干擾檢查。</p><p>　　為了滿足這些要求，可用一個基于特征和面向對象的分級模型來代替注射模。這樣便將模型分成許多部分，反過來由多段模型

17、和獨立部分組成。因此，一個分級的模型最適合于描述各組成部分之間的結構關系。一級表明一個裝配順序，另外，一個分級的模型還能說明一個部分相對于另一個部分的確定位置。</p><p>　　與直觀的固體模型操作相比，面向特征設計允許設計者在抽象上進行操作。它可以通過一最小套參數快速列出模型的特征、尺寸以及其方位。此外，由于特征模型的數據結構在幾何實體上的聯系，設計者更容易更改設計。如果沒有這些特征，設計者在構造固體模型幾

18、何特征時就必須考慮到所有需要的細節(jié)。而且面向特征的防真為設計者提供了更高級的成型對象。例如，模具設計者想象出一個澆口的實體形狀，電腦就能將這個澆口造型出來。</p><p>　　面向對象造型法是一種參照實物的概念去設計模型的新思維方式?；镜膱D素是能夠將數據庫和單一圖素的動作聯系起來的對象。面向對象的造型對理解問題并且設計程序和數據庫是很有用的。此外，面向對象的裝配體呈現方式使得“子”對象能繼承其“父”對象的信息

19、變得更容易。</p><p>　　Automated Assembly Modelling for Plastic Injection Moulds</p><p>　　X. G. Ye, J. Y. H. Fuh and K. S. Lee</p><p>　　Department of Mechanical and Production Engineering,

20、 National University of Singapore, Singapore</p><p>　　An injection mould is a mechanical assembly that consists of product-dependent parts and product-independent parts. Thispaper addresses the two key issue

21、s of assembly modellingfor injection moulds, namely, representing an injection mouldassembly in a computer and determining the position andorientation of a product-independent part in an assembly. Afeature-based and obje

22、ct-oriented representation is proposedto represent the hierarchical assembly of injection moulds.This representation requires a</p><p>　　Keywords: Assembly modelling; Feature-based; Injectionmoulds; Object-

23、oriented</p><p>　　Introduction</p><p>　　Injection moulding is the most important process for manufacturingplastic moulded products. The necessary equipment consistsof two main elements, the inje

24、ction moulding machineand the injection mould. The injection moulding machines usedtoday are so-called universal machines, onto which variousmoulds for plastic parts with different geometries can bemounted, within certai

25、n dimension limits, but the injectionmould design has to change with plastic products. For differentmoulding geometries, diffe</p><p>　　The design of a product-dependent part is based on extractingthe geomet

26、ry from the plastic product. In recent years,CAD/CAM technology has been successfully used to helpmould designers to design the product-dependent parts. The automatic generation of the geometrical shape for a productdepe

27、ndentpart from the plastic product has also attracted alot of research interest [1,2]. However, little work has beencarried out on the assembly modelling of injection moulds,although it is as important as the </p>

28、<p>　　This paper gives a brief review of related research inassembly modelling, and presents an integrated representationfor the injection mould assembly. A simplified geometric symbolicmethod is proposed to determ

29、ine the position and orientationof a part in the mould assembly. An example of automaticassembly modelling of an injection mould is illustrated. </p><p>　　Related Research</p><p>　　Assembly mode

30、lling has been the subject of research in diversefields, such as, kinematics, AI, and geometric modelling. Libardiet al. [3] compiled a research review of assembly modelling.They reported that many researchers had used g

31、raphstructures to model assembly topology. In this graph scheme,the components are represented by nodes, and transformationmatrices are attached to arcs. However, the transformation matrices are not coupled together, whi

32、ch seriously affects the transformation procedu</p><p>　　Automatically inferring the configuration of components in an assembly means that designers can avoid specifying the transformation matrices directly.

33、 Moreover, the position of a component will change whenever the size and position of its reference component are modified. There exist three techniques to infer the position and orientation of a component in the</p>

34、;<p>　　assembly: iterative numerical technique, symbolic algebraic technique, and symbolic geometric technique. Lee and Gossard [5] proposed an iterative numerical technique to compute the location and orientation

35、 of each component from the spatial relationships. Their method consists of three steps: generation of the constraint equations, reducing the number of equations, and solving the equations. There are 16 equations for “ag

36、ainst” condition, 18 equations for “fit” condition, 6 property equations f</p><p>　　Kramer [7] developed a symbolic geometric approach for determining the positions and orientations of rigid bodies that sati

37、sfy a set of geometric constraints. Reasoning about the geometric bodies is performed symbolically by generating a sequence of actions to satisfy each constraint incrementally, which results in the reduction of the objec

38、t’s available degrees of freedom (DOF). The fundamental reference entity used by Kramer is called a “marker”, that is a point and two orthogonal axes. Seven </p><p>　　Although many researchers have been acti

39、vely involved in assembly modelling, little literature has been reported on feature based assembly modelling for injection mould design.</p><p>　　Kruth et al. [9] developed a design support system for an inj

40、ection mould. Their system supported the assembly design for injection moulds through high-level functional mould</p><p>　　objects (components and features). Because their system was based on AutoCAD, it cou

41、ld only accommodate wire-frame and simple solid models.</p><p>　　3. Representation of Injection Mould Assemblies</p><p>　　The two key issues of automated assembly modelling for injection moulds

42、are, representing a mould assembly in computers, and determining the position and orientation of a product- independent part in the assembly. In this section, we present an object-oriented and feature-based representatio

43、n for assemblies of injection moulds.</p><p>　　The representation of assemblies in a computer involves structural and spatial relationships between individual parts. Such a representation must support the co

44、nstruction of an assembly from all the given parts, changes in the relative positioning of parts, and manipulation of the assembly as a whole. Moreover, the representations of assemblies must meet the following requireme

45、nts from designers:</p><p>　　1. It should be possible to have high-level objects ready to use while mould designers think on the level of realworld objects.</p><p>　　2. The representation of ass

46、emblies should encapsulate operational functions to automate routine processes such as pocketing and interference checks. To meet these requirements, a feature-based and object-oriented hierarchical model is proposed to

47、represent injection moulds. An assembly may be divided into subassemblies, which in turn consists of subassemblies and/or individual components. Thus, a hierarchical model is most appropriate for representing the structu

48、ral relations between components</p><p>　　Feature-based design [10] allows designers to work at a somewhat higher level of abstraction than that possible with the direct use of solid modellers. Geometric fea

49、tures are instanced, sized, and located quickly by the user by specifying a minimum set of parameters, while the feature modeller works out the details. Also, it is easy to make design changes because of the associativit

50、ies between geometric entities maintained in the data structure of feature modellers. Without features, designers h</p><p>　　Object-oriented modelling [11,12] is a new way of thinking about problems using mo

51、dels organised around real-world concepts. The fundamental entity is the object, which combines both data structures and behaviour in a single entity. Objectoriented models are useful for understanding problems and desig

52、ning programs and databases. In addition, the objectoriented representation of assemblies makes it easy for a “child” object to inherit information from its “parent”.</p><p>　　References</p><p>

53、　　[1]. K. H. Shin and K. Lee, “Design of side cores of injection moulds from automatic detection of interference faces”, Journal of Design and Manufacturing, 3(3), pp. 225–236, December 1993.</p><p>　　[2]. Y

54、. F. Zhang, K. S. Lee, Y. Wang, J. Y. H. Fuh and A. Y. C. Nee, “Automatic slider core creation for designing slider/lifter of injection moulds”, CIRP International Conference and Exhibition on Design and Production of Di

55、es and Moulds, pp. 33–38, Turkey, 19–21 June 1997.</p><p>　　[3]. E. C. Libardi, J. R. Dixon and M. K. Simmon, “Computer environments for design of mechanical assemblies: A research review”, Engineering with

56、Computers, 3(3), pp. 121–136, 1988.</p><p>　　[4]. K. Lee and D. C. Gossard, “A hierarchical data structure for representing assemblies”, Computer-Aided Design, 17(1), pp. 15– 19, January 1985.</p><

57、;p>　　[5]. K. Lee and D. Gossard, “Inference of position of components in an assembly”, Computer-Aided Design, 17(1), pp. 20–24, January</p><p><b>　　1985.</b></p><p>　　[6]. A. P. A

58、mbler and R. J. Popplestone, “Inferring the positions of bodies from specified spatial relationships”, Artificial Intelligence, 6, pp. 157–174, 1975.</p><p>　　[7]. G. Kramer, Solving Geometric Constraint Sys

59、tems: A Case Study in Kinematics, MIT Press, Cambridge, MA, 1992.</p><p>　　[8]. J. J. Shah and M. T. Rogers, “Assembly modelling as an extension of feature-based design”, Research in Engineering Design, 5(3&

60、amp;4), pp. 218–237, 1993.</p><p>　　[9]. J. P. Kruth, R. Willems and D. Lecluse, “A design support system using high level mould objects”, CIRP International Conference and Exhibition on Design and Productio

61、n of Dies and Moulds, pp. 39–44, Turkey, 19–21 June, 1997.</p><p>　　[10]. J. J. Shah, “Assessment of feature technology”, Computer-Aided Design, 23(5), pp. 331–343, June 1991.</p><p>　　[11]. S.

62、R. Gorti, A. Gupta, G. J. Kim, R. D. Sriram and A. Wong, “An objection-oriented representation for product and design process”, Computer-Aided Design, 30(7), pp. 489–501, June 1998.</p><p>　　[12]. J. Rumbaug

63、h, M. Blaha, W. Premerlani, et al. Object-Oriented Modeling and Design, Prentice Hall, Englewood Cliffs, NJ, 1991.</p><p>　　[13]. Unigraphics Essentials User Manual, Unigraphics Solution Co., Maryland Height