Control device for machine tool with time estimation unit for estimating time until motor reaches overheat temperature

A control device for a machine tool including a motor for driving a spindle, the control device comprising:

• a current detection unit that detects a current driving the motor;
• a temperature-increase-value estimation unit that estimates a temperature increase value due to copper loss of the motor to be produced when the current detected by the current detection unit continuously passes through the motor;
• a storage unit that stores overheat temperature specified for the motor;
• a time estimation unit that estimates, by using the temperature increase value due to the copper loss and the overheat temperature, time from when present estimation takes place until the motor reaches the overheat temperature, under a condition in which the current used for estimating the temperature increase value due to the copper loss continuously passes through the motor;
• and
• a provision unit that provides the time estimated by the time estimation unit.