A hybrid method for recognition of undercut features from moulded parts

摘要

Products manufactured by moulding processes, such as injection moulding or die casting, are called moulded parts. This paper describes a hybrid method to recognise undercut features from moulded parts with planar, quadric and free-from surfaces. The hybrid method takes advantage of graph-based and hint-based approaches. Various undercut features, including interacting undercut features, are defined by extended attributed face-edge graphs (EAFEG). Unlike conventional graph-based methods, which recognise features by graph matching, the new approach recognises the undercut features by searching the cut-sets of subgraphs. Face properties and parting lines are used as hints to guide the search of cut-sets. To recognise undercut features from parts with free-form surfaces, a convex-hull algorithm is used to determine the face properties (positive, negative and horizontal). The case study shows that the proposed method can recognise various undercut features successfully.