Stabilized-core injection molding of hollow thin-walled plastic products

Abstract

In a mold for injection molding and controlling the dimensions of a hollow plastic product having side walls, in which a first mold part and a second mold part define a mold cavity therebetween, encompasssed by a parting line, for forming the hollow plastic product, and further define a gate for admitting molten injected plastic into the cavity; one of the mold parts includes a retractable portion adjacent the gate, with the retractable portion being removable between a protracted position and a retracted position while the mold is closed; and the mold parts define primary flow channels extending from the gate, which, when the retractable portion of the one mold part is protracted, direct initially injected molten plastic from the gate to create stabilizing regions of stiffened plastic, to thereby impede lateral deflection of the mold parts with respect to each other when additional molten plastic subsequently is injected; whereby the side walls of the molded plastic product are uniformly dimensioned. The mold part/s further define secondary flow channels, which are significantly thicker than adjacent portions of the mold cavity; which are adjacent to the gate but, when the retractable portion is protracted, are isolated from the gate by the retractable portion, which are interposed between the primary flow channels; and which, when the retractable portion is retracted, direct the subsequently injected molten plastic between the stabilizing regions of stiffened plastic and into the side-wall-defining region of the mold cavity, to thereby enhance the flow of the molten plastic into the side-wall-defining regions of the mold cavity.

Dependencies are inferred from the claim text.