METHOD OF CONTROLLING DRIVE OF DRIVING MOTOR FOR ROTARY INDEXING DEVICE OF MACHINE TOOL

摘要

A method of controlling a drive motor is provided not to make defects and not to make the drive motor overloaded by driving output torque of the drive motor for position control less than output torque of the drive motor for deviation of angular position. A method of controlling a drive motor has a torque command monitoring circuit(57) which has a comparator(57a) comparing the commanded torque with the detected torque obtained from a detector(57b). When the commanded torque is higher than the allowable torque(Tp), the comparator emits a switching signal(Cs) to a switch(SW) in the speed deviation amplifier(53b) to make the switch open. As a result, torque command(Tc) outputted from the speed deviation amplifier becomes a proportionally controlled speed value(Sd) reflecting deviation of position.