Abstract: A numerical control grinding machine, in which rough grinding and finish grinding wheels are used to machine a workpiece into a predetermined shape. A sensor detects the finish grinding wheel contacting the workpiece surface when shifting from the rough grinding to finish grinding operations and determines its position. The numerical controller of the grinding machine calculates the difference between actual and theoretical sizes of the workpiece and completion of the rough grinding operation based on the finish grinding wheel position. After that, the controller compensates the rough grinding wheel position in the next machining cycle for the difference calculated by the controller.

Abstract: A numerically controlled internal grinding machine for grinding a workpiece by a rough grinding operation with a rough grinding wheel and a finish grinding operation with a finish grinding wheel. The grinding machine detects the load power of a motor which drives the finish grinding wheel in order to determine a compensation value to enable subsequent compensation due to wear of the rough grinding wheel. In the successive rough grinding operation, the relative position of the workpiece is compensated for according to the determined compensation value, so that the diameter of the workpiece after the rough grinding operation is maintained at a desired constant value regardless of the wear of the rough grinding wheel.

Abstract: A numerically controlled machine tool for machining a non-circular workpiece according to profile data. The numerical controller stores phase compensation values and position compensation data files in connection with the types of cam and the various rotational speeds of the main spindle. Each position compensation data file consists of a series of position compensation values for a successive rotational positions of the main spindle. The numerical controller searches a phase compensation value and a position compensation data file according to the type of cam to be ground and the rotational speed of the main spindle during the grinding operation. Thereafter, the numerical controller offsets the read-out position of the profile data by the amount corresponding to the searched phase compensation value, and compensates each profile data with position compensation data stored in the searched file so as to eliminate a machining error which changes depending upon the rotational speed of the main spindle.