CONTROL DEVICE FOR MACHINE TOOL INCLUDING ROTARY INDEXING DEVICE

摘要

A rotary table is rotated by a machining load. A drive motor tries to return the rotary table to a positioned target position, and increases output torque. When the output torque reaches upper limit torque Tmax or when output torque which is equal to or greater than permissible torque Tp continues for predetermined time ΔT, a target position which is sent to a drive motor is changed, thereby promoting reduction in output torque. If the output torque becomes smaller than permissible torque Tp, the target position is changed to bring position deviation of the drive motor equal to 0, and the position deviation is swiftly returned.

主权项

1. A control device for a machine tool including a rotary indexing device, the rotary indexing device comprising:
a rotary table on which a work is mounted and fixed; a clamping mechanism for clamping the rotary table; and a drive motor which includes a motor controller configured to control a rotation position and speed, and rotate and drive the rotary table, wherein the control device comprises drive motor output torque detecting unit configured to detect output torque of the drive motor, a position deviation detecting unit configured to detect position deviation from the motor controller, and a target position changing unit in which the rotary table is configured to be clamped by the clamping mechanism at a target position of a predetermined rotation angle position, and on a condition that time during which output torque of the drive motor detected by the drive motor output torque detecting unit is equal to or higher than a preset permissible torque continues for predetermined time or the output torque of the drive motor detected by the drive motor output torque detecting unit reaches preset upper limit torque while a work mounted on the rotary table is being machined, configured to change a target position such that the output torque of the drive motor is brought close to or equal to 0 if the detected output torque is equal to or higher than the permissible torque, and change the target position by increments such that detected position deviation is brought close to or equal to 0 if the detected output torque is smaller than the permissible torque.