Algorithms for the minimization of setups and tool changes in “simply fixturable” components in milling

Abstract Fixture planning is a complex task and has been a major stumbling block in the development of efficient automated planning systems. However, the recent emergence of universal fixturing techniques has provided hardware solutions to problems previously handled through software. These techniques permit the workpiece to be immobilized in any given orientation regardless of its shape. Components in which fixturing concerns can be ignored during planning are referred to as “simply fixturable”. In simply fixturable components, the entire space of feasible plans can be captured in a single unified graph-theoretic representation. In this paper, a robust graph-theoretic model of planning is presented along with a new hierarchical prioritization of the objectives in planning. This permits efficient yet comprehensive searches for near-optimal 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 plans with preferable squaring routines. An attempt is made to maintain theoretical soundness in these algorithms so that a variety of situations can be handled gracefully.

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