Development of in-situ measuring system of circularity in precision cylindrical grinding

The present paper describes a newly developed in-situ measuring system of the circularity of a workpiece in cylindrical grinding. The principle of the measurement is based on Three-Point Method. In this system, however, apparent runouts of a ground surface are measured at various angular positions by using only one displacement detector, which can be displaced around the workpiece axis with a stepping motor and in the radial direction with a piezo-actuator. In order to improve the measuring accuracy, the circularity profiles are determined by averaging five different measurements. By applying the developed system to a cylindrical grinding machine, it has been confirmed that the measured circularity profiles are in good agreement within submicron accuracy with those measured by using a circularity measuring instrument.