Control device for machine tool and machine tool

A controller for a machine tool having a feeder relatively moving a cutting tool and a material, and having a motor relatively rotating at least one of the cutting tool and the material with respect one another,

• the controller configured to:
• control an operation of the feeder and the motor while vibrating the cutting tool relative to the material by combining a forward feed movement in a machining direction, in which the cutting tool machines the material, and a return movement in a counter-machining direction different from the machining direction,
• wherein the controller is further configured to:
• calculate a return position of the cutting tool at a time when one vibration is completed using a number of vibrations and an amount of feed that are predetermined for one rotation of the cutting tool or the material as parameters;
• and
• output a pulse signal that includes a command for moving the cutting tool to a change point from the machining direction to the counter-machining direction, and a command for moving the cutting tool from the change point to the return position in the counter-machining direction, and
• wherein the pulse signal is formed in a sine waveform with an inflection point, and a phase of the inflection point for making the cutting tool reach the change point is set to a value different from a phase of the change point.