Fixture configuration using projective geometry

Abstract

Abstract Fixtures play an active role in many manufacturing operations such as machining, assembly, inspection, and welding. This wide application of fixtures and the increasing use of automation in design and manufacturing has aroused considerable interest in automated fixture design (AFD). Although a good amount of literature is available on this subject, most of the work done in this area has been restricted to prismatic parts. In this paper, a set of algorithms is presented to determine the fixturing locations considering orientation and geometry of a non-prismatic workpiece, and magnitudes and directions of cutting forces. The algorithms discussed here employ heuristic search techniques on the projected envelope of the workpiece to determine the locating and clamping points. The application of projective geometry reduces the complexity of the fixture configuration problem because search operations then degenerate from 3-D to 2-D. Five major steps of the algorithms are described and illustrated. The solution obtained is used as a fixturing recommendation that can be further refined by considering other factors such as workpiece deformation and cutter interferences.