機(jī)械設(shè)計(jì)外文翻譯--從cad系統(tǒng)模架和特征中提取處理計(jì)劃信息（英文）

1、Computers in Industry 30 (1996) 145-162 Extracting process planning information from various wire frame and feature based CAD systems J.-P. Kruth *, G. Van Zeir, J. Detand Kutholieke Unirersiteit L.muen, Department of M

2、echanical Engineering, Division P.M.A, Celestijnenlaan 3OOB, B-3001 Lawen, Belgium Received 23 November 1995; revised 7 June 1996; accepted 7 June 1996 Abstract In recent years, features have been identified by the engin

3、eering community as meaningful abstractions with which humans can reason about products and processes. From the designer’s point of view, features are functional primitives, which serve as the basis for sufficient

4、product representation, improving the quality of design and the link to life cycle activities, such as process planning and manufacturing. Up to now, virtually no commercial wire frame CAD system gives the user the pos

5、sibility to design with features. All objects in a drawing are loose CAD entities (points, lines, arcs,...) that can not be recognised as features. Feature based CAD systems mostly offer the user a fixed feature catalogu

6、e to design with. In many cases this feature catalogue is too rigid (a fixed set of feature types with fixed parameters) and does not correspond to the features that are used in a company for other feature based applicat

7、ions (e.g. process planning, NC programming,...). This paper describes a method for defining and extracting user definable manufacturing feature information from several wire frame and feature based CAD systems. This m

8、ethod is applied m a software module that interfaces CAD systems and a feature based process planning system [ 18,191. The development of this module, called the CAD Process Planning Interface (CAD PPI), was carried o

9、ut in the framework of the Esprit project 6805 COMPLAN [22]. KeFbrords: Feature based design/CAPP; Multiple feature views; CAD/CAPP integration: Feature modelling for CAPP; Neutral Program- ming Interface; Concurrent

10、engineering 1. Introduction In recent years, features have been identified by the engineering community as meaningful abstrac- tions with which humans can reason about products and processes. This introduction expla

11、ins where the use of features originates from and summarises some Corresponding author. Em ail: jean- pierre.kruth@mech.kuleuven.ac.be methods for identifying features on a part design. Further it reveals what fe

12、ature identification and extraction methods are applied in the developed soft- ware that is described in this paper. Some of the important concepts and methods used in the develop- ments of the CAD Process Planning I

13、nterface (CAD PPI) are described in Section 2 of this paper. With these concepts in mind, it is easier to understand the modular CAD PPI architecture, explained in Section 3. An example of how to use the developed soft

14、ware for a sample part is described in Section 4. Section 5 summarises the achieved results. 0166-3615/96/$15.00 ColJyright 0 1996 Elsevier Science All rights reserved. P/f SO 166.3615(96)00039-5 J.-P. Kruth et al./ Co

15、mputers in Industry 30 (1996) 145-162 147 engineering specifications. Designing with manufac- turing features restricts the designer to a limited set of design primitives (e.g. only material removal primitives)

16、 [7], and is therefore only useful for a limited, and well defined workpiece spectrum. * Conversion of design features to manufactur- ing features and manufacturability analysis The design is executed making us

17、e of design features, and incorporate geometric as well as tech- nological data, the latter being defined in the CAD system as attributes associated to the respective fea- ture(s). However, this design feature

18、 based view needs to be converted into a set of manufacturing features. Practical tasks involved in these mappings are described in [3,9,34]. Other systems enable to analyse the part during the design process and

19、 gener- ate suggestions for improving the machinability of the part [6,10,25] 1.3. The author’s approach The feature identification approach, that has been selected within this research, is the interactive one, mai

20、nly because it applies to 2D and 3D wire frame CAD systems (still representing 80% of the indus- trial CAD applications). Moreover, interactive fea- ture identification can be applied to feature based CAD systems.

21、 Following two methods were inte- grated for extracting manufacturing feature informa- tion: - For wire frame CAD systems, the features are extracted semi-automatically. First, the user must select a set of geomet

22、ry (e.g. two arcs) and indicate the kind of manufacturing feature to as- sociate this geometry to (e.g. a hole). Next, the developed “CAYD Process Planning Interface” (CAD PPI) for wire frame can automatically e

23、x- tract the feature parameters. The CAD PPI runs on a wide rangt: of CAD systems, through the concept of a Neutral CAD Programming Interface (NH. * For feature based CAD systems, the manufac- turing features are

24、 extracted directly from the CAD database (since the part was designed with features). One or more design features are matched onto a manufacturing feature. The CAD PPI for both feature based and wire frame CAD syste

25、ms can automatically extract fea- ture parameters as well as workpiece parameters. The result of both extraction methods is a full de- scription of the workpiece, including all feature pa- rameters and feature r

26、elations. The CAD PPI can be easily configured (extendible and user definable) to company specific feature and workpiece types. 2. Concepts used in the developments This section presents some important concepts

27、that are used in the developments of the CAD PPI. First it is explained why an extendible and customis- able feature catalogue is used in the implementation. Next, the “neutral programming interface” concept explai

28、ns why the software can run on a wide range of wire frame CAD systems. Further, the difference between generic features and user defined features is elaborated for both wire frame and feature based CAD systems. Finall

29、y, the importance of technologi- cal feature information (beside geometrical parame- ters> with respect to process planning is made clear. 2.1. Standard us. extendible feature catalogue An important dilemma of fea

30、ture based modelling is that many methods can be used for synthesising parts by features, and this makes the number of features virtually infinite. There are two options to overcome this infinity: * define a standar

31、d (fixed) feature catalogue, . use a customisable (extendible) feature catalogue. Many attempts have been made to define a stan- dard feature catalogue, among others the CAM-I process planning feature catalogue o

32、f John Deere [5], describing a hierarchy of process planning oriented features and the PDES/STEP catalogue (IS0 CD 10303) containing design oriented features. Those catalogues are rather elaborate (up to over

33、 a hundred features), but still suffer from incompleteness, and are not always corresponding to the engineering practice of specific companies. An extendible (versus a fixed) feature catalogue allows to define compa

34、ny specific design (and pro- cess planning) knowledge in a straight-forward and customised fashion (i.e. current practice can be re- tained) without too much information (i.e. about twenty features can cover 90