Hot plastic injection bushing

Abstract

A hot plastic injection bushing for delivering molten plastic molding material from an injection molding machine to a cavity mold in which the bushing comprises a smooth bore tubular member, the bore of which is adapted to pass the molten plastic from the molding machine to one or more parts of the mold. The tubular member is heated by means of a heat pipe surrounding the tubular member. The heat pipe comprises an evacuated chamber partially filled with a vaporizable liquid and is heated by means of an external electrical heater automatically controlled to maintain the temperature of the heat pipe at a desired value. The heat pipe is provided with internal wicking along a localized portion and the heater is located adjacent the wicking. The heat pipe operates to maintain all parts of the tubular bore at the same temperature and the bushing maintains the plastic material in the bore in its molten state between successive molding injections except for a small plug in an output area.

Dependencies are inferred from the claim text.