基于约束的三维特征可变零件模型的研究

为提高ＣＡＤ／ＣＡＭ系统的智能化和集成化，本文提出了一种基于约束和特征设计的零件定义模型，该模型采用了一套新型的特征定义、分类、表达方法，并鉴于短维约束的特征，对三维特征约束进行高层抽象，分为特征内约束、特征间约束，特征内约束表示为定型约束Ｃｓ，特征间约束表示为依存约束Ｃｄ、定全约束Ｃｐ、形状依赖Ｃｓｄ。在此基础上，通过有向特征多叉树（Ｄｉｒｅｃｔｅｄ Ｆｅａｔｕｒｅ Ｍｕｌｔｉｂｒａｎｃｈ Ｔｒ

A Study of Variable Part Model Based Constraint and 3-D Feature

To improve the integration and intelligence degree of the CAD/CAM system,this paper presents a part definition model based on constraints and feature technology.In this model a series of new methods are introduced to define,classify and represent features.According to characteristics of 3D constraints,they are classified as constraints inside feature and constraints between features through high level abstraction.The former classification is represented as shape constraint,and the latter one is represented as dependent constraint,location constraint and shape dependence.On this basis,a directed feature multibranch tree has been built to maintain the part constraint model.Moreover,three kind algorithms are also developed to build part model and edit part model,and erase feature.