Machine tool

摘要

A tool rest 20 is so provided that it can be driven to move in the X, Z axial direction and rotate with the B axis as a center to be placed at each angle. A cutting pattern computing portion 8 is so provided to compute cutting patterns PAT1 and PAT2 for the screw-machining to be executed rotating the turning tool with the B axis as a center and positioning it based on the machining information input by the input means. The screw-machining on a workpiece is executed based on the computed cutting patterns PAT1 and PAT2. Because the screw-machining is so executed as to rotate the turning tool with the B axis as a center and position it, it is possible to machine screws with flank portions of various inclination by a single tool, without machining flank portions of ridges by the tools, as the convention, fitting with the inclination of the each flank portion.