Apparatus for molding composite metal-elastomer wheels

In apparatus for molding a composite styled wheel of the type comprising a metal part consisting of a metal disc and rim subassembly operable as metal street wheel when a pneumatic tire is mounted on said rim, and a decorative urethane plastic body permanently molded to said metal part at the outboard face thereof, said molding apparatus comprising a base mold part configured to receive said metal part thereagainst and having an annular lip adapted for sealing engagement against an annular portion of the outboard face of said metal wheel radially outwardly of the center of the disc in the closed condition of said molding apparatus, said base mold part having a mold cavity surface to provide an ornamental configuration for the outboard face of the plastic body of the composite wheel, said mold cavity surface in said closed condition defining with at least part of the outboard face of said metal part a mold cavity axially adjacent the outboard face of said metal part, and a clamp adapted to seat in closed condition against the inboard face of said metal part at least adjacent the outer perimeter of said disc for urging said metal part into said sealing engagement with said base mold part, said mold parts being axially separable from one another to open said molding apparatus and to clear said metal part from said clamp and base mold parts, the improvement wherein said clamp includes funnel means adapted for registry with a liquid urethane reaction mixture injection nozzle coupled with injection mixing apparatus, said funnel means having a nozzle passage registering with the inboard side of a pour opening in said disc in the closed condition of said mold, and sprue pin means affixed to said base mold part in juxtaposed relation to said disc pour opening, said sprue pin means being adapted to cooperate with said disc pour opening to define a restricted annular access opening to said mold cavity during the injection pour of said urethane reaction mixture, said sprue pin means being operable to restrict back-flow of said reaction material via said pour opening during gelation of the same in the cure cycle, said sprue pin means being adapted to cooperate with said disc in the vicinity of said pour opening to define a zone of weakness in the cured urethane reaction mixture operable to induce fracture in said zone upon separation of said clamp funnel means from said metal part to thereby cause cleavage of said urethane reaction material adjacent the inboard surface of said metal part.