FIXTURE CONFIGURATION USING PROJECTIVE GEOMETRY

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 manufactu ring has aroused considerable interest in automated fixture design (AF D). Although a good amount of literature is available on this subject, most of the work done in this area has been restricted to prismatic p arts. In this paper, a set of algorithms is presented to determine the fixturing locations considering orientation and geometry of a non-pri smatic workpiece, and magnitudes and directions of cutting forces. The algorithms discussed here employ heuristic search techniques on the p rojected envelope of the workpiece to determine the locating and clamp ing points. The application of Projective geometry reduces the complex ity of the fixture configuration problem because search operations the n degenerate from 3-D to 2-D. Five major steps of the algorithms are d escribed and illustrated. The solution obtained is used as a fixturing recommendation that can be further refined by considering other facto rs such as workpiece deformation and cutter interferences.