Patent ID: 6286751
Filing Date: 2001-09-11
Classification: B29C

Abstract:
A method of making a melt dividing bushing having a rear end and a front end for use in a multi-cavity hot runner injection molding apparatus having a plurality of heated nozzles in a mold for dividing a melt passage extending therethrough from a single inlet to four outlets at the front end thereof, comprising the steps of;(a) making first, second and third layers, each layer having a rear and a front face,(b) drilling two spaced holes through the second layer from the rear face to the front face,(c) drilling four spaced holes through the third layer from the rear face to the front face,(d) machining matching grooves in the front face of the first layer and the rear face of the second layer to form a first melt conduit branching from the single inlet to the two spaced holes extending through the second layer,(e) machining matching grooves in the front face of the second layer and the rear face of the third layer to form two second melt conduits, each of said second melt conduits branching from one of the two spaced holes through the second layer to two of the four spaced holes through the third layer,(f) applying a brazing material to at least one of the front surface of the first layer and the rear surface of the second layer and to at least one of the front surface of the second layer and the rear surface of the third layer,(g) assembling the first, second and third layers with the front surface of the first layer abutting against the rear surface of the second layer and the front surface of the second layer abutting against the rear surface of the third layer, and(h) heating the assembled first, second and third layers in a vacuum furnace to a predetermined temperature under a partial vacuum according to a predetermined cycle whereby the brazing material flows between the first, second and third layers and integrally brazes them together to form the melt dividing bushing wherein the melt passage extends from the single inlet through the first melt conduit, the two spaced holes through the second layer, the two second melt conduits and the four spaced holes through the third layer to the four outlets at the front end of the melt dividing bushing.