WORKING METHOD OF DIE FOR USE FOR FRESNEL LENS, DIE WORKED THROUGH EXECUTION OF THE WORKING METHOD, AND FRESNEL LENS WORKED FROM THE DIE

摘要

A method for working a die for use with a Fresnel lens, the method being intended to work in an original die plate having a Fresnel molding groove with wall surfaces corresponding to a lens surface and a non-lens surface of the Fresnel lens. A cutting tool having one piece of edge line continuing to a blade end is constructed as a cutting edge. The blade end has formed therein a notched portion which connects the one piece of edge line and another piece of edge line. Thereby, while a relative rotating movement around a center line of the die is made between the cutting tool and the original die plate, the cutting tool is fed into the original die plate with the cutting edge being used as the leading blade.