Method and tool for creating a concave surface from a spectacle blank

摘要

A method for creation of a surface from a rough blank for spectacles is which is suitable for both brittle-hard materials and for plastics uses makes use of a disk-shaped, rotation-symmetrical tool of relatively large diameter, by means of which the material to be taken off the rough blank is removed with high grinding or milling efficiency in at least two work steps-a plunge-cut step and a shaping step with material removed along a spiral path. The outcome of the last work step is a machining path traveling in a spiral from the outside to the inside with low residual apex height and relatively large apex spacing. The resulting surface needs only slight fine-grinding and polishing aftertreatment. As an option, both a rim machining step adapted to the form of the eyeglass frame and a work step faceting the rim of the eyeglasses can be integrated into the method. Furthermore, tools are proposed for carrying out the grinding and milling process.