Automatic Undercut Feature Recognition for Side Core Design of Injection Molds

Abstract

For any undercut region of a plastic molded part, a side core has to be designed to form the complex geometry while avoiding the interference between the injection mold and the plastic molded part (molding). Viewing undercuts as features in the context of injection mold design, this paper presents a new method to recognize both isolated and interacting undercut features extracted from a mold cavity or core. With the introduction of the face property and the EAFEG representation scheme, an undercut feature can be precisely defined by an undercut subgraph. Unlike conventional graph-based methods, which recognize features by graph matching, the proposed algorithm recognizes undercut features by searching the cut-sets of subgraphs. After recognizing undercut features, a Boolean operation is used to generate a side core for each undercut. Rules to eliminate the side core intersection are also presented for implementation.