面向3维CAD的PDM系统的研究与实现

针对3维计算机辅助设计存在的问题，提出了面向3维计算机辅助设计的产品数据管理系统整体结构，其重点是实体约束和关联管理。通过对约束和关联进行语法定义，设计关系类记录约束和关联信息，支持了设计过程中相关设计对象的同步更新，提供了对设计过程和知识管理的支持。其他集成点包括计算机辅助设计格式转换平台、3维模型信息提取与交互以及3维模型与2维图纸的关联管理。在实现方法上，计算机辅助设计格式转换平台借助ACIS实现，提供计算机辅助设计通用浏览器和HSF格式浏览器；3维模型信息提取与交互通过计算机辅助设计提供的应用程序接口进行开发，并把数据管理操作菜单嵌入到计算机辅助设计系统内；3维模型与2维图纸的关联管理通过对模型和图纸进行同步检人和检出操作，解决3维模型与2维图纸的一致性。面向3维计算机辅助设计的产品数据管理系统已经实现并得到实际应用。

Research & implementation of PDM for 3D CAD

To deal with problems in three-dimension (3D) Computer Aided Design(CAD), the architecture of Product Data Management (PDM) system oriented to 3D CAD was designed which focused on entity constraints and relationships management.The semantic of constraint and relationship among entities was defined, and the classes of implementing relationship management were introduced. Entity constraint and relationship management supported simultaneous update of related parts within a design. It also helped to ensure consideration of the original design intent or specifications during engineering changes. At the same time, relationship management provided methods for process and knowledge management. Some auxiliary modules in PDM for 3D CAD were discussed. General CAD transform platform provided a viewer for displaying all kinds of 3D model, which were implemented based on ACIS. Attributes and structure information were extracted from 3D model, and function menus such as retrieval attributes were embedded inside CAD systems. Association between 3D model and two-dimension(2D) drawing was maintained in PDM, and the synchronous checking-in and checking-out keep consistency with 3D and 2D. The PDM for 3D CAD has been implemented in several projects.