Control device for machine tool

A control device of a machine tool, comprising:

• a feed axis driving motor;
• a spindle driving motor;
• a first power consumption calculating portion calculating power consumption of the feed axis driving motor or the spindle driving motor, using a time constant correlated with at least one of acceleration time and deceleration time of the feed axis driving motor or the spindle driving motor as a parameter;
• a cycle time calculating portion calculating a cycle time for machining a workpiece, the cycle time varying according to the time constant;
• a second power consumption calculating portion calculating power consumption of equipment provided at the machine tool and adapted to be operated by a constant power, based on the cycle time calculated by the cycle time calculating portion;
• and
• a motor control portion determining a target time constant based on a summation of the power consumption calculated by the first power consumption calculating portion and the power consumption calculated by the second power consumption calculating portion, and controlling the feed axis driving motor or the spindle driving motor based on the target time constant.