ALGORITHMS FOR THE MINIMIZATION OF SETUPS AND TOOL CHANGES IN SIMPLY FIXTURABLE COMPONENTS IN MILLING

Fixture planning is a complex task and has been a major stumbling bloc k in the development of efficient automated planning systems. However, the recent emergence of universal fixturing techniques has provided h ardware solutions to problems previously handled through software. The se techniques permit the workpiece to be immobilized in any given orie ntation regardless of its shape. Components in which fixturing concern s can be ignored during planning are referred to as ''simply fixturabl e.'' In simply fixturable components, the entire space of feasible pla ns can be captured in a single unified graph-theoretic representation. In this paper, a robust graph-theoretic model of planning is presente d along with a new hierarchical prioritization of the objectives in pl anning. This permits efficient yet comprehensive searches for near-opt imal plans that minimize multiple objectives. Algorithms are presented for selecting the access faces for features, minimizing the number of setups, minimizing the number of tool changes, and merging setup plan s with preferable squaring routines. An attempt is made to maintain th eoretical soundness in these algorithms so that a variety of situation s can be handled gracefully.