Abstract: To efficiently extract freeform machining feature from cavity parts,a novel approach was proposed and implemented by exploiting information implied in blend features.The blend features in mould cavity were recognized,and its types were determined based on type and number of seed faces.The character boundaries of blend feature were extracted to convert the surface information of blend feature into boundary information of machining feature.The topological faces of machining feature and the relation of features were recognized by making use of the shape and position information implied in the character boundary.Experimental results showed that the proposed approach was simple and feasible,and could efficiently recognize the freeform machining feature from cavity parts.The extracted data also could be integrated into CAD/CAM system to promote the integration of CAD and CAM.

Key words: cavity part, freeform machining, feature recognition, blend feature, process planning

摘要： 为有效提取模具型腔的曲面加工特征,提出一种新的曲面加工特征识别方法。该方法以过渡特征为加工特征识别的线索,识别模具型腔内的过渡特征,并根据其种子面的类型和个数确定过渡特征的类型;提取不同类型过渡特征的特征边界,将过渡特征的曲面信息转换为加工特征的边界信息;利用特征边界识别型腔内加工特征的拓扑面和特征间的拓扑关系。实验表明,该方法简单、可行,能有效识别模具型腔的曲面加工特征、提取工艺规划所需的集成性信息,促进该类产品的CAD/CAM集成。

关键词: 型腔零件, 曲面加工, 特征识别, 过渡特征, 工艺规划