CAD系统中的产品模型定义技术

本文在就实体造型、尺寸公差建模、非簇建模、参数化建模、约束建模和特征建模等技术作简要的评述后，提出了在现有ＣＡＤ系统基础上，实现产品特征建模系统开发的方法。系统利用特征定义将实体模型和特征模型紧密联系起来，特征识别和基于特征设计技术相互配合，使用户可自由地选取实体建模操作或特征建模操作来构造具有完整定义的产品模型。

PRODUCT MODEL DEFINITION TECHNIGUES IN CAD

The research for product model definition has ben around for many years. Several representations, such as solid modelling, Dimension & tolerance modelling, nonmanifold modelling,parametric modelling, constraint based modelling and feature-based modelling, having been propoode one after another. After surveying these technologies, the author present a novel theme in which feature-base, product modelling system is developed based on existing CAD system in this paper. The system associates the solid model with feature model closely by means of feature definition and combines both the feature recognition and design-by-feature methods. ms gives the user the freedem of choosing the most convenient means of expressing each required operations for completely defining product model.