End-supporter path scheduling for robot-assisted asymmetrical support machining of thin-walled parts with non-equal thickness and closed section

Abstract As a typical thin-walled workpiece with non-equal thickness and closed section, the steam turbine blade is easy to be deformed and to chatter in the machining process due to its low stiffness, which seriously affects the final machining quality. One effective way to solve this problem is to support the workpiece using an assisted robot simultaneously with machining. This paper aims at scheduling the path of the end-supporter during support machining, thus coordinating the cutter and the supporter. This is unconventional and significant because: (1) Due to the “non-equal thickness” feature of the thin-walled parts, the supporter path is not the equal-distance offset of the existing cutter path; (2) Due to the “closed section” feature of the thin-walled parts, cyclic cutter-location path is often adopted, which makes the interference among three bodies in terms of the workpiece, the cutter, and the supporter easy to occur. Therefore, to schedule harmonious and interference-free supporter path corresponding to the existing cutter-location path for support machining of the thin-walled parts, this paper proposes an equal chord-tangent angle method for generating the reasonable support path, followed by a spatial-mapping-based optimization method for generating the shortest interference-avoidance path. The support path and the interference-avoidance path formed the integral end-supporter path. Verification test demonstrates that the scheduled supporter path can not only coordinate with the original cutter, but also has no abrupt directional variation or spatial interferences.