Machining of aspherical molding dies utilizing parallel grinding method

This paper deals with a parallel grinding method for ultra-precise aspherical parts such as aspherical lenses, molding dies and mirrors. The needs of the improvement in image quality for the latest digital image equipments are steadily increasing, and a high accuracy of aspherical lenses has been strongly required. Therefore, the development of the more precise grinding technology for the aspherical glass lenses and glass molding dies is required. The parallel grinding method is an arc-envelope grinding method in which a grinding wheel with an arc-shaped cross-section is used to generate an aspherical profile. The property of the ground surface by the parallel grinding method and the conventional method (cross grinding method) was compared about tungsten carbide (WC) for glass lens molding dies. It is clear that a better surface quality is obtained by the parallel grinding method.