| 摘要 |
<p>This invention relates to a gate insert which screws into the forward end of an injection molding nozzle and a method of making it. The gate insert has an intermediate portion which extends between a threaded cylindrical rear portion which screws into the nozzle and a cylindrical nose portion which is secured in an opening in the cavity plate and forms the gate. A gradually tapered melt bore extends axially through the gate insert, and an electrical heating element is integrally embedded in the gate insert with a helical portion extending around the melt bore to maintain the temperature of the melt as it flows through the bore. The gate insert is made by forming a body portion with a neck portion having a tapered outer surface extending between the rear portion and the nose portion. A recess is machined in the tapered surface and a helical portion of the heating element is wound in the channel. A nut portion having a matching tapered inner surface is mounted on the neck portion. A slug of nickel alloy is placed in a filler tube which leads to a filler bore extending radially through the nut portion. The assembly is heated in a vacuum furnace to integrally cast the heating element in the channel and bond the nut portion to the body portion.</p> |
