Determining feasible tool-approach directions for machining Bézier curves and surfaces

To link CAD data, computer-aided process planning and computer-aided manufacturing directly, it is necessary to determine a direction from which a feature can be approached for machining without interference from other portions of the part. This direction is called the tool-approach direction. It is used for determining the feasibility of machining the part, determining the tool orientation and part fixturing. The problem of finding all feasible tool-approach directions for machining Bézier curves and surfaces by using CAD data is presented in the paper. The paper discusses 3-axes machining with a ball-end cutter to generate Bézier curves and Bézier surfaces. The algorithms are developed based on subdivision of the control polygon, and proofs to demonstrate the correctness of the algorithms are presented. Test results indicating performance of the algorithms are also discussed.