Abstract: For the difficulties in machining knowledge mining,the geometric evolution of recognition on machining features in plan process was proposed to be the foundation of knowledge mining.The virtual machining datum attribution was presented,and the attributed adjacency graph of machining model was constructed,in which the corresponding faces were identified with the same global machining datum attribution.The integration of new faces,extinct faces and maintained faces were obtained by comparing graph of adjacent procedure.The broken faces,shape change faces and shape retentive faces were recognized by comparing parametric expression of corresponding maintained faces.The recognition algorithm of machining features changing was proposed,and the changing processes were recognized based on the relationship of different face type.The effectiveness of proposed recognition method was verified by an instance.

Key words: machining feature, geometric evolution, knowledge discovery

摘要： 针对机械加工的工艺知识挖掘困难问题,提出将从加工工艺中识别加工特征的几何演变过程作为加工工艺知识挖掘基础的理论。提出虚拟加工基准概念,构建工序模型的属性邻接图。通过模型表面的基准属性识别工序模型演变过程中的对应面序列;通过比较对应面的变化得到相邻工序的新增面、消亡面和保留面集合;通过比较保留面的NURBS参数表达式变化,识别被破坏面、形状变化面和形状不变面。提出加工特征几何演变识别算法,通过工序模型各个面的变化类型识别加工特征的几何演变过程。以典型零件工序模型实例验证了加工特征几何演变过程识别方法的有效性。

关键词: 加工特征, 几何演变, 知识发现