Patent ID: 6030198
Filing Date: 2000-02-29
Classification: B29C

Abstract:
In a multi-cavity hot runner injection molding apparatus for multi-layer molding having a front melt distribution manifold and a rear melt distribution manifold mounted in a mold extending substantially parallel to each other with an insulative air space therebetween, a plurality of heated nozzles, each heated nozzle having a rear end, a front end, a central melt channel extending therethrough from the rear end to the front end and an annular melt channel extending around the central melt channel to the front end with a plurality of spaced melt bores extending from the rear end of the heated nozzle to the annular melt channel, the heated nozzles being mounted in the mold with the rear end of each heated nozzle abutting against the front melt distribution manifold, the improvement wherein;a first melt passage from a first melt source branches in the rear melt distribution manifold and extends through the plurality of melt bores and the annular melt channel in each heated nozzle to a gate adjacent the front end of the heated nozzle leading to a cavity in the mold, and a second melt passage from a second melt source branches in the front melt distribution manifold and extends through the central melt channel in each heated nozzle to the gate, a plurality of melt transfer and dividing bushings each having a rear end and a front end and being mounted in an opening through the front melt distribution manifold, with the front end of the melt transfer and dividing bushings abutting against the rear end of one of the heated nozzles, each melt transfer and dividing bushing having a portion of the first melt passage extending therethrough from a common inlet and dividing therein to a plurality of spaced holes at the front end thereof, the common inlet being in alignment with the first melt passage in the rear melt distribution manifold and each hole at the front end thereof being in alignment with one of the melt bores extending from the rear end of the heated nozzle to the annular melt channel.