Patent ID: 9581989
Date: 2017-02-28
CPC Classifications: B23Q,G05B,H02H,H02K,H02P

Claim:
1. A control device of a machine tool comprising: a motor which drives a spindle, a current detection device which detects a value of current of said motor, a storage device in which an overheat temperature which is prescribed for said motor is stored, a temperature detection device which detects a temperature of said motor, a time estimation device which uses a temperature which is detected by said temperature detection device and said overheat temperature to estimate a time from a current point of time to when said motor reaches said overheat temperature in the case where a current which said current detection device detects continues to flow through said motor, a filter which receives as an input, the value of time which said time estimation device estimates, a time constant changing device which changes a filter time constant in said filter in accordance with either of a value of current and a current command value which is given when controlling the motor, and a display device which displays a value of time which said filter outputs, wherein time constant changing device decreases said filter time constant when either of said value of current or said current command value is a predetermined threshold value or more and increases said filter time constant when it is less than the predetermined threshold value.