Thick-walled plastic lens molding method, involves molding a thin walled component and increasing cavity size during continued injection to produce a thick walled component

摘要

An injection mold with a variable cavity size is closed to create a cavity (7a) for molding a thin walled component. Plastic is injected until the cavity is filled and then the cavity size is increased while simultaneously injecting plastic until a thick walled cavity (7b) and molding is attained. The tool can then be opened for product demolding. An Independent claim is made for the molding tool which has a cavity formed by first and second tool plates and a linearly-moving embossing punch in one of the plates. A recess in the plate which surrounds one end of the embossing punch extends along the stroke of the punch parallel to its movement and connects with the molding cavity. Preferred Features: A compression phase may be applied after filling the minimal sized cavity (7a) to reduce shrinkage marks on the molding. Compression may be repeated after completion of molding in the maximum sized cavity (7b).