Collapsible mold core

Claim 1

A collapsible mold core having cylindrical outer walls in its molding configuration, which comprises: an inner core member of the general shape of a truncated cone defining opposed first and second ends, said inner core member tapering transversely to a reduced diameter from said first end to the second end, and a plurality of outer core members, attached to the lateral exterior of said inner core member in longitudinally slidable relation thereto between first and second positions, said outer core members defining first ends and second ends corresponding in position to the first and second ends of the inner core member, said outer core members tapering inwardly in transverse dimension from their second ends to their first ends, to provide an opposite taper to that of the inner core member, key and keyway means providing longitudinally sliding attachment between said inner core member and outer core members, said outer core members including first outer core members defining an arcuate outer surface and converging inner surfaces connected at their edges to lateral edges of the outer surface and defining acute angles thereto, said first outer core members being spaced from each other in the first sliding position and having an inner wall in intimate sliding contact with the inner core member, and second outer core members positioned between said first outer core members, said second outer core members being of generally triangular cross section and defining a pair of inwardly-angled outer surfaces positioned in sliding relation with inner surfaces of adjacent first outer core members, said second outer core members each defining an arcuate, concave inner surface positioned in sliding relation with said inner core member, said inwardly-angled outer surfaces defining acute angles with the arcuate inner surface, said second outer core members each defining an outer arcuate apex surface positioned between outer edges of the inwardly angled outer surfaces and opposed to the arcuate inner surface, the arcuate outer surfaces of the first outer core members and the arcuate apex surfaces of the second outer core members defining, in the first sliding position, the outer side wall of said mold core, said mold core being substantially free of open interior spaces between said inner and outer core members in the first sliding position whereby said mold core is of lesser transverse diameter in said second sliding position than in the first sliding position, to permit molding of a cylindrical object about the mold core in the first sliding position, and removal of the object from the core in the second sliding position.