机械产品的特征信息处理

The Feature Information Processing of Mechanical Products

本文讨论了单纯采用CSG模型和单纯采用B-Rep模型来表达机械产品的特征信息时所遇到的一些实际困难,根据机械产品设计与制造一体化的特殊要求,提出了基于CSG+B-Rep数据结构的特征信息表达方案。其主要特点是以面为特征定义的基本单位,利用FSMTS中CSG与B-ReP的一致对应关系,将产品的特征信息PIT链入CSG和B-Rep组成的循环链中,其优点在于既可通过CSG摸型建立参数化的产品模型,又可通过交互方式定义和修改产品的特征信息。

This paper summarises the difficulties met in representating the mechanical product feature information by single CSG model or B-ReP model. According to the special requirements of integrated CAD/CAM systems, an method of feature information repre sentation is proposed based on the CSG + B-ReP data structure. The main characteristics of the method are that face is used as an unit for the feature definition; and making use of the coordinative relationship of CSG aad Rep in the FSMTS ( Feature Solid Modelling Tool System), product information table (PIT), CSG, and B-ReP are linked up to form an adjacency list. As the result, the parametric product model can be set up by the CSG description; the geometry can be defined, and the feature information can be added interactively throngh the B-ReP model.