Product information platform based on STEP

Abstract

Abstract：The international standard ISO 10303, called STEP, has been used to deal with problems in the exchange of product models and the associated data between different computer-aided systems. A platform based on STEP for managing product information is presented. This platform includes three components: a product geometry information model, a product feature model and a product visualization model. An information extracting pattern, in which information is extracted from low level elements to high level ones, is adopted in establishing the product geometry information model. Relative elements lists are created based on the extracted product information. With the traversing of these lists, feature extraction methods are proposed, which take advantage of boundary information in product model and avoid the determination of concavity and convexity of curves. Information correlating to features is stored in a structure named as feature block and the product visualization model is founded from it. The feature block is used in the platform for information communication and synchronous update among the three components. Keywords：ISO 10303 standard; STEP; feature extraction; feature block With the development of technology, more attention is paid to the problems in conjunctions among information technology and others. In machining area, with the spreading and implementing of computer-aided systems (CAD/CAPP/CAM etc), data expands rapidly from product design to manufacture. Information exchange of CAD models between different CAD systems or between CAD and downstream application systems spans more phases and covers more details. In order to deal with problems in data exchange among different systems, a lot of research has been made and several standards have been developed. ISO 10303 of the International Organization for Standardization (ISO), known as STEP (standard for the exchange of product model data) [1] , was developed for model data exchange without loss of any information. It provides a mechanism that describes a complete and unambiguous product definition throughout the life cycle of a product and can reduce the total life cycle of the product dramatically [2][3][4][5] .The scope of ISO 10303 is electronic data exchange for any form of discrete product. It is part-oriented, partly because of the need to cater for all types of systems, including any one that may not be feature-based. Details of information supporting feature definitions are therefore presented in the exchange file, but they are not identified in any way as being associated with specific features [6] . The exchange file is not suitable in the downstream applications such as process planning and manufacture. Although many CAD vendors provide preprocessor and postprocessor with product exchange files, and several of them provide add-in functions of extracting features from product model, the extracted features are mostly design features and are stored in their own databases. Structures of these databases are different from each other. For this re...

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