Lens edging maching bevel control process

摘要

An improved process for positioning a bevel along the edge of an opthamalic lens computes point-to-wheel data definitive of a planar relationship between the lens and the wheel, stores the point-to-wheel data, computes corrected horizontal displacement data definitive of a three dimensional relationship between the lens, the wheel and a plot of sequential contact points therebetween using the computed point-to-wheel data, stores the corrected horizontal displacement data, and controls the relative positions of the edging wheel and the lens in response to the corrected horizontal displacement data. The point-to-wheel data is computed by sequentially testing at successive incremental points of the point-to-wheel data at a beginning reference angle of the lens to determine a transition point at which the wheel ceases to increase and begins to decrease its displacement from the lens. This sequential testing is repeated at successive incremental points for sequentially successive incremental changes in the reference angle to determine a transition point for each incremental change. The corrected horizontal displacement data is computed by sequentially testing at successive incremental angles of a radius originating at a center of rotation of the lens at a beginning reference angle of the lens to determine an incremental angle at which the lens initiates contact with the wheel. This sequential testing is repeated at successive incremental angles at each sequentially successive incremental change in the reference angle to determine an incremental angle at which the lens initiates contact with the wheel for each incremental change. Preferably, the beginning reference angles and the successive incremental changes in the reference angle of the point-to-wheel computing and the corrected horizontal displacement computing are identical and sequential testing at successive incremental points and at successive incremental angles occurs simultaneously for each sequentially successive incremental change in the reference angle.