Study And Development Of XML-Based Modular Fixture Graphics Library

With the development and maturity of computer science theories, performance and efficiency of CAD systems are also enhanced and improved. Today, the comprehensive performance of stand-alone CAD system has reached a high point. However, each of the CAD system defines a CAD data format (model) applicable to its own subsystem, which hampered information exchange between CAD systems.The emergence of XML provides a new vision for solving the problem of information exchanges and presents a problem how to manage data of XML tags. The use, retrieval and operation of database for XML storage is becoming a promising approach, in other words, when putting data of XML tags into a framework, the work of search, analysis, update and output results can be completed in an environment that is easier to manage, more systematic and acquainted people with. Modular fixture graphics library was taken as an example and made a deep study of the XML expression, exchange of graphics information and management issues related to XML includes:(1)A XML-based method of CAD Data ExchangeToday the problems that CAD data exchange are facing with and necessity are analyzed, and a comprehensive comparison is made among a variety of graphics exchange technology. Based on that, XML solutions of CAD data exchange are proposed. Research status at home and abroad and performance in mechanical CAD system are also discussed.(2)A XML-based graphics information representationCSG modeling-based method on solid model is applied to graphic information of fixtures after some modeling methods of graphic information are analyzed and compared. The data model of fixture graphics is established by dividing fixture graphics into some elements and typical characteristics. Then data of basic elements and typical characteristics is depicted, data structure of fixture graphics can be finally got. At last, graphic data structure are mapped with XML hierarchy structure and graphic data also be mapped with XML elements.(3) XML data exchange technology based on a specific CAD platformA XML interface subsystem is developed under the UG (short for Unigraphics) platform. Under the platform, XML documents of fixture elements are converted into entities graphics successfully.(4)Management techniques of fixture library based on SML (tabular layouts of article characteristics)Fixture element data is described and managed by SML and parametric variant design of modular fixture is fulfilled by the variant design based on SML. By establishing the map relationship between SML and XML of fixture element, conversion between SML and XML data is finished,XML data management is also fulfilled.