Injection molding nozzle and method
OwnerJobst U. Gellertinventor
Life of this patent
Estimating the term…
Abstract
This invention relates to an improved injection molding nozzle and a method of making it. The nozzle has an electric heating element integrally vacuum cast in copper in spiral channels set in the outer surface of the tool steel nozzle body. The heating element has a cold terminal at one end which projects out through a hole in a head plate which is rotatable prior to casting to ensure the nozzle has a consistent length of heating element cast in. A sleeve is located over the spiral channel prior to casting to ensure the heating element in the channel is covered with a minimum depth of copper to dissipate the heat from the heating element. The spiral channel can be cut with a varying pitch according to a predetermined profile to provide more heat where there is more heat loss.
Claims14
A method of making an integral injection molding heated nozzle comprising the steps of:
- (a) forming an elongated steel body having a forward end and a rear end with a central bore extending therebetween, the body having a generally cylindrically outer surface with a head adjacent the rear end and a spiral channel extending therearound from adjacent the forward end to adjacent the rear end,
- (b) winding an electrically insulated heating element in the channel with one end fixed in the channel adjacent the forward end of the body and a cold terminal at the opposite end extending from the channel adjacent the rear end of the body,
- (c) locating a steel head plate on the head of the body, the head plate having a central opening therethrough which receives the head of the body in a position to cover the portion of the channel extending around the head, the head plate having a hole extending radially therethrough from the central opening to receive the end of the heating element having the cold terminal, whereby the head plate can be slightly rotated on the head of the body to provide a predetermined length of the heating element projecting therefrom to compensate for slight variations in winding the heating element in the spiral channel,
- (d) inserting the forward end of the body into a steel sleeve to a position wherein the sleeve covers the spiral channel between the head and the forward end of the body, the sleeve having an inner diameter slightly larger than the outer diameter of the outer surface of the body,
- (e) sealing the joints around the sleeve and the head plate and sealing around the cold terminal to prevent substantial leakage,
- (f) securing a filler reservoir in communication with the spiral channel and inserting a predetermined quantity of copper in the filler tube,
- (g) casting the assembly in a vacuum furnace to melt the copper which flows along the heating element to fill the spiral channel beneath the sleeve and the head plate to completely cover the heating element in the channel to a minimum depth and form an integral bond between the heating element and the surrounding steel body, and
- (h) machining the integral nozzle to remove the filler reservoir and to provide the desired shape and finish.
An integral injection molding heated nozzle comprising:
- (a) an elongated steel body having a forward end and a rear end with a central bore extending therebetween, the body having a generally cylindrical outer surface with an enlarged head adjacent the rear end and a spiral channel extending therearound from adjacent the foward end to adjacent the rear end, the head having a tapered outer surface,
- (b) a steel head plate having a central opening therethrough with a tapered inner surface which matches the tapered outer surface of the head of the body, the head plate being seated on the head of the body with the tapered inner surface abutting on the tapered outer surface of the head to cover the portion of the spiral channel extending around the head, the head plate having a hole extending radially outward therethrough from the central opening and transverse bolt holes to mount the nozzle in position in an injection molding system,
- (c) a steel sleeve extending around the body from adjacent the forward end, the sleeve having a steel collar fixed to one end which abuts against the head, the sleeve having an inner diameter slightly larger than the outer diameter of the outer surface whereby the sleeve and collar cover the spiral channel between the head an the forward end of the body, and
- (d) an electrically insulated heating element wound in the spiral channel to extend from one end adjacent the forward end of the body to an opposite end having a cold terminal connected thereto extending out through the radially extending hole through the head plate, the heating element being vacuum cast in copper which completely fills the spiral channel and forms an integral bond between the heating element and the surrounding steel body and integrally bonds the sleeve to the outer surface of the body.
Dependencies are inferred from the claim text.