Multiple zone heating of molds

Claim 1

An assembly for molding an article of heat-fusing plastisol material comprising; a mold having a mold surface and a backside surface, a plenum plate having openings therein, first and second sets of nozzles, each nozzle having an inlet end received in one of said openings, said first set of nozzles having jet outlets disposed adjacent the mold backside surface to direct a heating or cooling gas from said first set of nozzles to produce short flow paths of said gas flow across said backside surface over a first area thereof for controlling the temperature over said first area of the mold backside surface, said second set of nozzles having jet outlets disposed adjacent the mold backside surface over a second area thereof for producing short flow paths of a heating or cooling gas thereacross for controlling the temperature over said second area of the mold backside surface, and slide valve means including first and second thin plates having openings therein, said plates being slidable relative to each other and said plenum plate such that said openings may be selectively aligned with said nozzle inlet ends for controlling flow of said gas through said first and second sets of nozzles in a first operative position for maintaining the temperature of one of said first and second areas at a non-gelling temperature below that required to gel any appreciable thickness of the heat-fusing material and for heating another of the areas of said mold surface to a higher temperature than said first area for gelling material on a portion of the mold surface, said plates having a second operative position maintained during both fusion and cooling phases of operation wherein either heated gas or cooling gas is directed through all nozzles in both of said sets of nozzles whereby all areas of the mold are heated to a like fusion temperature or to an even cooling temperature for removal of fused parts from the mold.