零件的设计模型向毛坯模型转换技术研究

为了实现CAD／CAPP／CAM的集成，提出了一种由设计模型向毛坯模型转换、进而向制造模型转换的思想。文章重点研究了由设计模型向毛坯模型转换的技术。具体研究了毛坯模型的定义与生成技术，包括毛坯建模、毛坯模型的生成、切削区域的定义、分解性实体几何造型思想，以及结构实体几何特征模型向分解性实体造型的转化。还研究了设计模型向毛坯模型转换的实现方法。给出了实现这一转换的具体步骤为：识别零件表面、余量补偿、体加工面的识别和立体形状的构建、采用半空间法构建被移去的体特征和偏移量补充。

Transformation Technology from Part Design Model to Blank Model

To integrate CAD, CAPP and CAM, the thought of transforming part design model to blank model thus to manufacturing model was presented. The part design modeling is to get rid of features from blank model, while blank modeling is to add features to part design model and compensate for the surplus of processing. The blank modeling built geometric model according to the information from part drawing or CAD system. On the other hand, the information was also obtained from geometric model database by using feature-identification technology. Then, some segment of geometric model was compared with the predefined feature model from database, and the case with matching feature was recognized. After abstracting the identified feature, the features' parameters were confirmed and the geometric model of the feature was completed. The high-level features were acquired by combining various features. Furthermore, the information of blank was derived and the blank model was output. This kind of blank model is still related to the original part design model and keeps data consistency when the original design model is modified.