Double-Sided Processing оf Low-Hardness Lenses

The scheme of a device for processing lenses with convex-concave spherical surfaces of the negative meniscus type of average diameter, which allows flexible and wide control over the process of simultaneous bilateral abrasive shaping of the noted optical parts, is considered in the paper. Mathematical modeling of the processing of spherical surfaces using the free grinding method using a tool in the form of a mushroom and a cup was carried out. An analytical expression is obtained for calculating cutting paths, which, according to F. Preston’s formula, are proportional to the amount of material removed from the work-piece being processed. The calculation of cutting paths in the diametrical sections of the processed spherical surfaces was carried out. The calculation was performed for various values of such parameters of processing modes as the amplitude of the reciprocating rotational movement of the tools and the number of their double strokes per minute, as well as the rotation speed of the lens. In this case, the section with the greatest divergence of sliding paths was considered and the relative value of these paths was determined, which is proportional to the processing accuracy. Research has been carried out to establish that when correcting macro-errors on the actuating surface of the lens, it is most effective to change the amplitude of the reciprocating rotational movement of the tools, and these changes should be made within the range from the minimum value of this amplitude, determined by the design features of the specific basic technological equipment, to its value 0.65 of the diameter of the work-piece. In this case, to minimize local errors of the latter, it is advisable to set its rotation speed to 60–70 rpm.