Machine tool control system

Abstract

A machine tool control system moves a grinding wheel from a retracted position to a forward position by causing hydraulic fluid to be applied under pressure to a hydraulic cylinder to effect rapid forward movement of the grinding wheel to a forward position whereupon further movement of the grinding wheel to a final position is effected by supplying a predetermined number of pulses to a stepping motor for driving the feed screw in accordance with a predetermined sequence of grinding movements. Upon completion of the grinding operation, the grinding wheel is reset to the initial retracted position by applying hydraulic fluid to another portion of a cylinder to rapidly move the grinding wheel from the forward position to the retracted position while at the same time applying the same predetermined number of pulses to the stepping motor so as to reversely rotate the feed screw to return the grinding wheel to the initial position. To confirm an accurate resetting of the grinding wheel within an acceptable margin of error, a pulse generator operated by the actual movement of the feed screw produces verification pulses which are received by a reset confirmation circuit which at the conclusion of the resetting operation monitors a number of pulses corresponding to the acceptable margin of error to determine whether the grinding wheel has been reset to the initial position. If the reset confirmation circuit receives an insufficient number of verification pulses, indicating an underreset condition, or receives too many pulses within a period of time corresponding to the acceptable margin of error, indicating an overreset condition, then further operation of the machine tool will be prevented.