| 摘要 |
PROBLEM TO BE SOLVED: To prevent a driving motor mounted on a numerically controlled machine tool from overheating by precisely evaluating the load on the motor in real time. SOLUTION: This device is provided with a time setting means 4 which previously sets the time when the square mean load on the motor is computed, a program actuation detecting means 5 which detects an actuation signal actuating the numerically controlled machine tool by a processing program, a timing generating means 6 which generates an arithmetic start signal for the square mean load on the motor by the time setting means 4 and program actuation detecting means 5, and a load arithmetic means which starts the arithmetic of the square mean load on the motor and updates the arithmetic result with the arithmetic start signal. Cumulative addition and averaging processing for finding the square mean load on the motor is carried out in every period of a shorter time between the time up to the actuation of the processing program and the elapse of the previously set time.
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