Abstract: A digital servo-control apparatus which controls the rotation of a servomotor on the basis of a digital position command value representative of a target position and a digital position feedback value output from a position detecting device. The apparatus comprises a device for calculating a feedforward value at intervals of a predetermined period on the basis of the amount of change of the position command value, a device for delaying the position command value by a period of time corresponding to an operation delay in the feedforward value calculating device, a device for calculating a velocity command value by adding the feedforward value to a deviation of the position feedback value from the position command value delayed by the delay device, and a device for driving the servomotor according to the velocity command value determined by the calculating device.

Abstract: A synchronizing control apparatus for synchronously rotating master and slave main spindles of a pin grinder, wherein a servomotor for the slave main spindle is rotated at a speed corresponding to a compensated command value while the master main spindle is rotated at a speed corresponding to a noncompensated command value. The compensated command value is calculated based on a synchronizing error between the master and slave main spindles at a predetermined interval longer than the length of instable condition of a servo loop for the slave main spindle. When the synchronizing error is larger than a predetermined limit value, the command value for the slave main spindle is gradually compensated in order to prevent the compensated command value from changing too abruptly.

Abstract: When machining cams with the same profile data, finished shape errors tend to increase as the diameter of a grinding wheel decreases. In order to keep the finished shape errors within a tolerance, the profile data used for machining must be renewed with new profile data corresponding to the present diameter of the grinding wheel. In the disclosed numerically controlled cam grinding machine, optimum wheel diameters, at which new profile data must be calculated, are decided automatically. The numerical controller calculates the marginal diameters which require renewal of profile data based upon the machining tolerance when a new grinding wheel is attached to the wheel head. After that, the numerical controller calculates new profile data from the marginal wheel diameter and lift data, when the present wheel diameter reaches into one of the marginal wheel diameters. The old profile data is renewed with the newly calculated profile data corresponding to the marginal wheel diameter.

Abstract: A synchronous control system for a pair of spindles of a machine tool including a master spindle and a slave spindle. Current positions of the main spindles are detected, and a deviation between the detected current positions is calculated. In case the deviation is within 180 degrees, the current position of one of the main spindles which precedes in the forward direction of rotation is determined as a target position for positioning. In case the deviation is greater than 180 degrees, the detected current position of the master spindle or the slave spindle is offset by an amount equal to an integral number of times 180 degrees so that the deviation between current positions of the main spindles after such offset is within 180 degrees. Then, that one of the current position of the main spindle thus offset and the current position of the other main spindle not offset which precedes in the forward direction of rotation is determined as a common target position for positioning.

Abstract: A numerically controlled machine tool for machining a non-circular workpiece according to profile data. The numerical controller of the machine tool memorizes the ideal profile data calculated from the ideal final shape of the workpiece, and the execution profile data calculated from the ideal profile data and compensated for position error due to the follow delay of the machine tool. The machine tool is controlled according to the execution profile data during grinding the workpiece with cut-in feed and spark-out grinding. The numerical controller has the capability of measuring position change of the main spindle and the tool slide during spark-out grinding. Then, the numerical controller ascertains whether or not the follow delays of the main spindle and the tool slide are within a prescribed tolerance depending on the measured position change and the ideal profile data.