Apparatus for producing centrally apertured record discs

Abstract

An injection molding apparatus for use in producing centrally-apertured video disc records. The apparatus includes first and second mold halves reciprocally movable with respect to each other between a closed position, wherein the two mold halves are in proximity to each other and molten plastic material is injected into a planar, annular cavity defined therebetween to form the record disc, and an open position, wherein the two mold halves are spaced apart from each other and the molded record disc can be removed. The molding apparatus further includes first and second annular rings carried by the respective first and second mold halves and defining the outer perimeter of the cavity. Each ring has an abutment face for compressive engagement with the abutment face of the other ring, when the apparatus is in the closed position, and one of the rings includes a plurality of spaced, radially-aligned grooves in its abutment face, defining ports for venting air from the cavity when the molten material is injected therein. The first mold half includes two plates reciprocally movable with respect to each other, with a plurality of compression springs in the form of polyurethane blocks interposed between the two plates, to bias the two annular rings into compressive engagement with each other when a central aperture is being punched in the molded record disc. When the apparatus is in the closed position, the two mold halves are aligned with respect to each other by a plurality of frusto-conical posts mounted on one mold half and conformably received by corresponding recesses formed on the other mold half, such posts and recesses not being subject to wear from sliding friction when the apparatus is moved, reciprocally, between the closed and open positions.

Dependencies are inferred from the claim text.