Pressure stabilized injection mold

Claim 1

A mold assembly for injection molding a container having parallel thin walled partitions comprising: a base; a plurality of cores cantileveredly mounted to said base, said cores spaced apart defining partition forming spaces and having free distal ends to form the bottom of said container; a cavity assembly movably mounted to enclose said cores but spaced therefrom across a gap to form said container therein; parallel wedges mounted on said cavity assembly and movable therewith to an engaging position whereat said wedges extend into some of said spaces between and against adjacent free distal ends of said cores limiting movement together of said cores so engaged; side locking means mounted with said cavity assembly for limited motion transverse to the direction of core extension and when in one position extending into sideways engagement with the outermost cores limiting outward movement thereof; and, injection means mounted with said cavity assembly and aligned with those of said spaces not associated with said wedges and being spaced apart from said wedges a distance at least equal to from one of said spaces to another of said spaces and operable to inject plastic material into those spaces at a pressure sufficient to limit movement of said cores forming those spaces and cooperatively with said wedges limiting movement of said cores and by stabilizing said free distal ends forming said partition of uniform thickness.

Claim 11

A method of injection molding a plastic container having compartments separated by thin walled partitions comprising the steps of: spacing apart a plurality of upstanding cores of a male mold each a distance equal to the desired thickness of said partitions; positioning a female mold around said male mold but spaced therefrom to form said container therebetween; inserting wedges between some of said cores; injecting plastic material at a certain pressure with injectors between the remaining cores and between the male mold and said female mold; and, maintaining said wedges in place to limit movement of cores engaged by said wedges while maintaining said pressure to limit movement of the remaining cores until said plastic material has flowed between all of said cores and between said cores and female mold.

Claim 12

A method of injection molding a plastic container having compartments separated by thin walled partitions comprising the steps of: spacing apart a plurality of upstanding cores of a male mold each a distance equal to the desired thickness of said partitions; positioning a female mold around said male mold but spaced therefrom to form said container therebetween; inserting wedges between some of said cores; injecting plastic material at a certain pressure with injectors between the remaining cores and between the male mold and said female mold; and, maintaining said wedges in place to limit movement of cores engaged by said wedges while maintaining said pressure to limit movement of the remaining cores until said plastic material has flowed between all of said cores and between said cores and female mold.