LENS THICKNESS ADJUSTMENT IN PLASTIC INJECTION MOLD

摘要

Method and apparatus for lens thickness adjustment in injection molding of thermoplastic vision-corrective spectacle lenses without manual addition or removal of shims, of inserts or of any other mold part. Thickness adjustment can be made quickly between molding cycles while the lens mold is kept at hot operating temperatures without burning the operator. A rotatable adjustment head (11) is mounted externally onto the mold's operator side, and manually-driven rotation turns a threaded screw (10) which engages a mechanical assembly which produces an axially perpendicular motion which in turn drives forward or back the settable position of an optically polished insert (5) within the lens mold's cavity (16). As shown here, this manually-driven rotation turns a worm gear mechanism (55) driving wheel (18) which rotates a threaded male shaft (56) within a mated threaded female bore (57) axially perpendicular to the parting line (4-4). The shaft's rotational displacement produces an axial change in the separation distance of the opposing inserts (5 and 6), and thereby changes the lens thickness. Alternatively, a toggle mechanism (Fig. 6) replaces the worm gear, shaft and bore assembly.