INJECTION MOLDING NOZZLE WITH HEATING ELEMENT THAT IS NOT PARTIALLY HEATED AND ITS PRODUCTION

摘要

PURPOSE: To provide an injection molding nozzle to which a heating element supplies substantially little heat along a part of the nozzle adjacent to an external thermal and a method for manufacturing the injection molding nozzle. CONSTITUTION: This injection molding nozzle has an electrical heating element 42 extending into a pair of alternating coils in a spiral channel around a central melt passage and a method for manufacturing this injection molding nozzle is provided. The heating element 42 has a U-shaped bend near the forward end of the nozzle 10 and two ends at an external terminal near the backward end. A central wire in the heating element 42 has the heating portion of a fine coil 70 between two large diameter conductive portions extending to the terminal. One of the conductive portions of the central wire is longer than the other by a specified distance and extends to one of the alternating coils of the heating element 42 along the rear portion of the nozzle adjacent to the terminal. The heating portion of the wire extends in both of the alternating coils of the heating element 42 along the forward portion of the nozzle 10. The heating element 42 emits substantially less heat along the rear portion than along the forward portion of the nozzle.