板材冲裁和翻口工艺特征识别及图形转换的研究

该文针对冲孔、翻孔两类板材冲压成形工艺方法的主要特点，设计了两类成形件的特征识别规则．根据形状特征与冲压加工特征间存在着单映射的关系，可以充分利用模型中的几何信息和拓扑关系来识别零件的特征．因板材零件的厚度与整个零件尺寸比较是小的，可以假设零件厚度为常数．在消除厚度边和厚度边组成的面后，其余边和面分成上、下两组．两组的几何边界和拓扑结构是相同的，上、下两面的法向矢量方向相反．通过对读入的IGES三维线框文件进行预处理，使之满足特征识别的需要，采用基于几何推理的特征识别技术实现了对冲压件主型面特征、冲孔特征、翻孔特征的识别与提取，从而为后期冲压工艺方案的制定做准备．

Stamping Feature Recognition and Graphics Transformation System

Based on main characteristics of punching and flanging process, this paper describes the design of rules to (recognize) stamping features. Taking into account the unique mapping existing between the shape features and stamping process features, geometrical information and topology are used to re-(cognize) features of the parts. Since the thickness of parts is small compared with overall size, the thickness can be regarded as constant. By ignoring the joints between edges in the thickness direction, the remaining sides and faces are categorized into two groups, one on the top and the other on the bottom. The topology and geometrical boundaries of the two groups are the same and the normal vectors are in opposite directions. The shape of the part can be represented by any set of faces and the other can be formed by translation. The first recognized set of faces is called primary faces. The close regions of the primary faces are then recognized, thereby stamp features can be recognized. By using this method, the system can recognize and extract typical stamp features such as primary face feature, punch feature and flange feature.