Tool damage prevention system

Abstract

A tool damage prevention system is provided which can easily detect an abnormal load with high accuracy to reliably prevent damage to a tool, and which also can appropriately cope with abnormality even if tool damage or the like has already occurred. A first disturbance torque estimating device estimates a disturbance torque Ys acting on a spindle motor, based on a velocity signal X1s from the spindle motor (spindle) and a torque command value U1s for the spindle motor. A second disturbance torque estimating device estimates a disturbance torque Yz acting on a servomotor, based on a velocity signal X1z from the servomotor (feed shaft) and a torque command value U1z for the servomotor. A comparing device obtains a composite disturbance torque Y by combining the estimated disturbance torques Ys and Yz, and compares the composite disturbance torque Y with a preset reference torque Ye. A deceleration/stop command device outputs a command signal to decelerate or stop the tool feed or to change the tool in accordance with the result of the comparison.

Dependencies are inferred from the claim text.