Controller for chip cutting when processing a rotating workpiece

A controller configured to control a machine tool which performs thread cutting for a rotating workpiece by moving a cutting tool pressed against the workpiece, according to a machining program, the controller comprising:

• a cutting-up/cutting-in motion operating condition analysis unit configured to analyze operating conditions of a cutting-up/cutting-in motion commanded in the machining program;
• and
• a cutting-up/cutting-in motion insertion unit configured to insert a cutting-up/cutting-in motion created based on the operating conditions analyzed by the cutting-up/cutting-in motion operating condition analysis unit into the thread cutting,
• wherein the cutting-up/cutting-in motion insertion unit is configured to repeatedly perform, along a thread groove cutting direction, a cycle including performing:
• a cutting-in operation from a start position where the cutting tool cuts into the workpiece to a predetermined depth,
• when the cutting-in operation is complete, a cutting-up operation which cuts chips into pieces by raising the cutting tool for cutting in the radial direction of the workpiece so that the cutting tool escapes to an outside of an outer diameter of the workpiece when the thread is an external thread, or so that the cutting tool escapes to an inside of an inner diameter of the workpiece when the thread is an internal thread, and
• when the cutting-up operation is complete, an operation to cause the cutting tool to approach a subsequent start position for execution of a subsequent cutting-in operation, wherein the approach is a path of the cutting tool that is determined so that the cutting tool does not interfere with the workpiece during the approach to the subsequent start position.