US Patent No. 9,527,176

CONTROL DEVICE FOR MACHINE TOOL INCLUDING ROTARY INDEXING DEVICE


Patent No. 9,527,176
Issue Date December 27, 2016
Title Control Device For Machine Tool Including Rotary Indexing Device
Inventorship Yoshitsugu Ogawa, Yamanashi (JP)
Assignee FANUC CORPORATION, Yamanashi (JP)

Claim of US Patent No. 9,527,176

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 to be mounted and fixed;
a clamping mechanism configured to clamp the rotary table;
a drive motor configured to rotate and drive the rotary table; and
a motor controller configured to control a rotation position and a speed of the drive motor,
wherein the rotary table is configured to be clamped by the clamping mechanism at a target position of a predetermined rotation
angle position,

wherein the control device comprises a processor configured to
detect an output torque of the drive motor,
obtain a position deviation from the motor controller, and
execute a target position changing processing on a condition that a time, during which the detected output torque of the drive
motor is equal to or higher than a preset permissible torque, continues for a predetermined time or the detected output torque
of the drive motor reaches a preset upper limit torque while a work mounted on the rotary table is being machined, and

wherein, in executing the target position changing processing, the processor is configured to
change the 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 the obtained position deviation is brought close to or equal to 0 if the
detected output torque is smaller than the permissible torque.