Manufacturing method for selected gate configuration injection molding nozzles
OwnerJobst U. Gellertinventor
Life of this patent
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Abstract
This invention relates to an improved method of making nozzles for injection molding. The nozzles are heated by an electrical heating element which is cast in a copper portion between inner and outer stainless steel portions. The method includes making a main rear portion and a steel nose cap portion separately, brazing them together in a vacuum furnace to form an integral unit, and then finishing it by drilling and machining to provide it with a central bore and a particular gating configuration. This method has the advantage that a single inventory of unfinished nozzles can be maintained, from which a requirement for one of several gating configurations can be quickly supplied by finishing the nozzles according to that configuration.
Claims12
A method of manufacturing an injection molding nozzle to have a selected one of several gating configurations, the nozzle being elongated with rear and forward ends and having a helical electrical heating element integrally cast in a highly thermally conductive portion between corrosion resistant inner and outer portions, the inner portion having a central bore to convey melt from an inlet at the rear end to the selected gating configuration at the forward end having at least one outlet, comprising the steps of:
- (a) forming a main rear portion of the nozzle by assembling the helical heating element in a space between a corrosion resistant inner member and a corrosion resistant outer member, sealing the space against leakage during casting, casting highly thermally conductive material into the space to form an integral structure, and machining the rear portion to have a forward end of a predetermined shape;
- (b) forming a steel forward nose cap portion with a rear end shaped to fit the forward end of the main rear portion, the nose cap portion being of sufficient size to provide any of the several gating configurations. sufficient size to provide any of the several gating configurations.
- (c) fitting the rear portion and the nose cap portion together after applying brazing material between them, and heating them under a partial vacuum for a sufficient period of time and at a temperature to integrally braze the steel nose cap portion onto the main rear portion;
- and
- (d) drilling amd machining the nozzle to form the central bore which extends from the rear end of the nozzle, and to provide the nose cap portion with the predetermined selected gating configuration to connect the central bore with at least one outlet leading to a gate.
Dependencies are inferred from the claim text.