Abstract: Aiming at NC machining for surface similar to revolution body with high feed rate, a tool path planning method with toroid cutter under helix driving mode is proposed. Firstly, a helical line is constructed as the guide curve of the surface. Secondly, the initial cutter contact (CC) point corresponding with the subsquent guide point is estimated based on the tangential direction of the CC point locus known on the surface, and the center of the toroid cutter at the initial CC point is calculated. Thirdly, the distances between the initial cutter center and the objective cutter location (CL) point corresponding with the subsqent guide point in circumferential direction and axial direction are computed. Then the direction and step for searching the objective CC point are figured out with the quasi similarity relation between adjacent CL points and adjacent CC points. Finally the objective CC point and CL point are searched with an iterative process. Also the error calculation method is proposed based on analyzing the curvature of the surface and the cutter at CC point. The algorithm is used in tool path planning of shoe last 5-axis NC machining. The result shows that the algorithm works with a high searching efficiency and it has value of both theory and application. The shoe last 5-axis NC machining experiment is also carried out, which verifies the effectiveness of the algorithm.

Key words: NC machining, Surface similar to revolution body, Tool path planning, Toroid cutter