Importance

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Abstract

In a plastic lens grinding machine of the type having a head mounted on a base and adapted to carry a lens pattern and a plastic lens having a base curvature, the head is capable of movement parallel to the axis of rotation of the plastic lens. A carriage is mounted on the base and is movable perpendicular to said axis of rotation, with the carriage having an improved rotatable cutter with a cutting edge made of a metal of high hardness and adapted to be rotated at high speed in order to be self-coolant. A hydraulic damper is mounted on the carriage and connected to the base for regulating the gravitational movement of the carriage towards the axis of rotation of the plastic lens, thus regulating the engagement of the metallic cutter blade with the periphery of the plastic lens. An improved bevel aligning device is provided having a base curve cam connected to the head and a cam tracer connected to the carriage, with the cam having a surface forming the same base curvature as the plastic lens. The tracer is in bearing contact with the surface of the cam and effects a movement of the head with the lens in a first direction to a position that aligns the center of the lens with the beveling device. The bevel aligning device further includes a biasing spring connected to the head and to the base for effecting movement of the head in a circular direction resulting in bearing contact of the surface of the cam against the tracer. By this arrangement, when the lens and the lens pattern are rotated, with the cutter being rotated at high speed, the carriage moves toward the axis of rotation thereby effecting an engagement of the cutter with the plastic lens periphery. The cutter cuts and edges the plastic lens while the beveling device simultaneously forms a bevel at the center of the periphery of the plastic lens.

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First Claim