基于特征的层次式公差信息表示模型及其实现

HIERACHICAL REPRESENTATION MODEL AND ITS REALIZATION OF TOLERANCE BASED ON FEATURE

在自动特征识别的基础上,提出了基于特征的层次式公差信息的表示模型,共分为三层:基于特征的拓扑与技术相联表面层;最小特征基准元层;约束元层,并在三层之间定义了密切的联系。接着给出模型的实现方法,形成了层次式的公差表示模型,实现了公差信息的工程语义表示及其在CAD系统中的有机集成,这对于CAD/CAM的集成有着重要意义。

Different types of tolerance are defined for different functional and manufacturing requirements and each type of tolerance is represented in a way suitable for it to fully take advantage of a computer implementation of tolerance. A hierarchical tolerance representation model is proposed in our study. The model is divided into three tiers: the tier of the topologi-cally and technologically related surfaces(FTTRS), the tier of the minimum feature datum elements(MFDE) and the tier of constraint primitive(CP). The relationship between them is also studied and defined. After this, the realization of the model is given. Using this tolerance, the seamless integration of tolerance information in CAD system is realized.