Characterization and identification of forming features for 3-D sheet metal components

This paper- presents a new classification system for forming operations, and concepts for extracting and recognizing forming feature from the 3-D sheet metal component created in a wireframe model. A set of principles is developed for characterizing forming features geometrically and topologically. Forming features are extracted by identifying 3-D component graph and subgraphs by vector normal method and vertex fusion methodology. Further, various planes and their type in the component graph are identified, and adjacency plane relationship between them is determined. Cross bend features are extracted by identifying common edges. Pattern recognition is then done using isomorphism principle and a set of characterization principles developed for forming features. A flat pattern is developed for the 3-D component and shearing features are identified. Recognized pressworking features help in the integration of Computer Aided Process Planning (CAPP), codification system, mapping of tools, inspection of tools, etc. The system has been tested for live components. (C) 2001 Elsevier Science Ltd. All rights reserved.