Injection molding nozzle having grounded heating element brazed into pointed tip.

摘要

This invention relates to an improved injection molding nozzle having an integral electrical heating element. The nozzle (10) has an elongated nose portion (26) extending to a forward end from a cylindrical central portion. The heating element (76) is brazed in a spiral channel around a central melt bore (70) in the central portion of the nozzle, and extends into the nose portion to a forward end which is grounded by brazing it in nickel adjacent a high speed steel insert (92) portion at the forward end of the nozzle. This forms a pointed tip at the forward end of the nozzle which is corrosion and wear resistant and can be heated to a predetermined temperature. In alternative embodiments, the forward end of the heating element can be brazed in nickel adjacent the forward end without the high speed steel insert portion and/or the nose portion can be inclined with the forward end of the heating element being grounded adjacent an end gate rather than a separate gate. The mass of the central portion and the elongated tapered shape of the nose portion which permits relatively rapid temperature changes of the melt in the gate area enable the nozzle having a single heating element to be used for temperature assisted gating.