INJECTION MOLDING NOZZLE WITH REPLACEABLE GATE INSERT

摘要

A sprue gated injection molding system having nozzles with a removable hollow gate insert received in a seat in the forward end of each nozzle to form the gate. Each gage insert has a forward portion with a tapered outer surface which abuts against a matching tapered surface of an opening through to mold to the cavity. The forward portion of the gate insert is resilient which ensures extremely good contact between them under bearing pressure due to thermal expansion of the nozzle. Thus optimum uniform heat transfer is provided between the gate insert and the cooled mold. The gate insert has a circumferential removal flange to facilitate it being pryed out of the seat if replacement is required. In an alternate embodiment an elongated torpedo is seated centrally in the melt bore of each nozzle. The torpedo has an outer retaining ring and a number of radially extending tapered fins which form melt flow channels between them. The torpedo is mounted with the retaining ring secured in the seat in the forward end of the nozzle by the gate insert and a pointed tip formed by the fins extending to provide additional heat in or adjacent the gate. The torpedo has pointed tips at opposite ends and is reversible for different dimensioned applications.