On-Line Non-Contact System for Grinding Wheel Wear Measurement

Abstract

An on-line non-contact method for measuring the wear of a form grinding wheel is presented. A CCD (charge coupled device) camera with a selected optical lens and a frame grabber was used to capture the image of a grinding wheel. The analogue signals of the image were transformed into corresponding digital grey level values. Using the binarisation technique, the images of background and the grinding wheel were segmented. Thus the grinding wheel edge was identified. The 'mapping function method' is used to transform an image pixel coordinate to a space coordinate. An auto-focus technology is also developed. The statistics of pixels are used as the focusing index. The signal was sent through an 8255 control card to drive a d.c. motor, and then to control the lens focusing movement to acquire the focal plane. The images before and after the grinding process were captured. The position deviation of the grinding wheel edge was analysed. Then, the grinding wheel wear was evaluated. The wear detection accuracy is about 1μm.