| 摘要 |
This invention relates to an improved method of making an improved injection molding nozzle (10) having an integral electrical heating element (76) which is grounded adjacent the corrosion and wear resistant pointed tip (32). A main body is made of steel with a cylindrical central portion (18) and a tapered portion (26) adjacent a forward recessed end. The heating element is inserted through a heating element bore (134) drilled diagonally through the tapered portion and wound in a spiral channel (78) machined in the surface of the central portion A high speed steel tapered tip portion is mounted on the forward end of the main body with the exposed forward end of the heating element extending into a central heating element bore therethrough. The surfaces of the assembly are sprayed with sticky acrylic lacquer (176) and it is then dipped in a nickel powder bath (178). Beads of nickel brazing paste (164, 168, 172) are applied to the joints. A high speed steel insert portion (92) is dropped into the mouth of the bore (146), followed by a quantity of nickel brazing powder (184). The assembly is then heated in a vacuum furnace (174) which brazes it integrally together, forms a protective coating and grounds the forward end of the heating element adjacent the insert portion all in a single insertion. The nose portion is machined to have a pointed tip which is corrosion and wear resistant and can be heated to a predetermined temperature. |
