Pressure-based in-process measurement by the null method for automatic compensation of wheel wear during surface grinding

Abstract

This paper deals with automatic compensation of grinding wheel wear in wet grinding by pressure-based in-process measurement. A pressure sensor is set close to a grinding wheel with a small gap. When grinding fluid is dragged into the gap by the rotation, the wear of the grinding wheel can be predicted by using hydrodynamic pressure that has been generated, which corresponds to the gap thickness and topography of the surface. This method was applied to a numerically controlled surface grinding machine. Some characteristics of the pressure were measured. The pressure sensor was repositioned to keep the pressure constant with the null method. The spindle was also repositioned according to the sensor displacement, which was equal to the worn thickness of the grinding wheel. The error of the ground depth with compensation was less than the feeding step for the compensation. The measurement performance by the null method was compared with that obtained without compensation, with compensation by a deflection method and by the contact method.