INJECTION MOLDING NOZZLE WITH REPLACEABLE GATE INSERT

摘要

ABSTRACT OF THE DISCLOSUREA sprue gated injection molding system havingnozzles with a removable hollow gate insert received in aseat in the forward end of each nozzle to form the gate.Each gage insert has a forward portion with a taperedouter surface which abuts against a matching taperedsurface of an opening through to mold to the cavity. Theforward portion of the gate insert is resilient whichensures extremely good contact between them under bearingpressure due to thermal expansion of the nozzle. Thusoptimum uniform heat transfer is provided between the gateinsert and the cooled mold. The gate insert has acircumferential removal flange to facilitate it beingpryed out of the seat if replacement is required. In analternate embodiment an elongated torpedo is seatedcentrally in the melt bore of each nozzle. The torpedohas an outer retaining ring and a number of radiallyextending tapered fins which form melt flow channelsbetween them. The torpedo is mounted with the retainingring secured in the seat in the forward end of the nozzleby the gate insert and a pointed tip formed by the finsextending to provide additional heat in or adjacent thegate. The torpedo has pointed tips at opposite ends andis reversible for different dimensioned applications.