Motor control apparatus capable of protecting process face at the time of occurrence of abnormal load

Abstract

A motor control apparatus controlling a motor driving a machine tool includes, an abnormal load detecting unit that detects an abnormal load by monitoring a load of the motor, a retract amount storing unit that stores a plurality of retract amounts used when the machine tool performs a retract operation in response to detection of an abnormal load by the abnormal load detecting unit, a retract amount switching unit that switches a retract amount selected from the plurality of retract amounts in accordance with a result of determination of whether the machine tool is processing or not, and a retract amount adding unit that adds a retract amount selected by switching of the retract amount switching unit to an instruction value indicative of a movement amount of the machine tool.

What is claimed is: 
     
         1 . A motor control apparatus controlling a motor driving a machine tool, comprising:
 an abnormal load detecting unit that detects an abnormal load by monitoring a load of the motor;   a retract amount storing unit that stores a plurality of retract amounts used when the machine tool performs a retract operation in response to detection of an abnormal load by the abnormal load detecting unit;   a retract amount switching unit that switches a retract amount selected from the plurality of retract amounts in accordance with a result of determination of whether the machine tool is processing or not; and   a retract amount adding unit that adds a retract amount selected by switching of the retract amount switching unit to an instruction value indicative of a movement amount of the machine tool,   wherein a retract amount selected when it is determined that processing is being made and a retract amount selected when it is determined that processing is not being made are switched.   
     
     
         2 . The motor control apparatus according to  claim 1 , wherein the retract amount switching unit switches a retract amount to be selected in accordance with a mode signal input from a host controller. 
     
     
         3 . The motor control apparatus according to  claim 1 , wherein the retract amount switching unit switches a retract amount to be selected in accordance with a switch signal input from an external device. 
     
     
         4 . The motor control apparatus according to  claim 1 , wherein a retract amount selected when it is determined that the machine tool is processing is rewritten in accordance with a process program used. 
     
     
         5 . The motor control apparatus according to  claim 1 , wherein a retract amount selected when it is determined that the machine tool is processing is rewritten in accordance with a process state of a workpiece processed by the machine tool.