Injection molding nozzle with thermocouple tube

In an injection molding nozzle to be mounted in a well in a cooled mold, the nozzle having a rear end, a forward end, a rear collar portion adjacent the rear end, and a central portion extending forwardly from the rear collar portion, the central portion having a generally cylindrical outer surface and the rear collar portion being larger in diameter than the central portion, the nozzle having a melt channel extending therethrough to convey melt from an inlet at the rear end towards at least one gate extending through the mold to a cavity, the nozzle having an integral electrical heating element with a spiral portion extending around at least a portion of the melt channel, the nozzle having a cylindrical locating flange extending a predetermined distance forwardly from the rear collar portion around the central portion, the locating flange having an inner surface spaced from the outer surface of the central portion by an insulative space having a predetermined width, the rear collar portion of the nozzle having a thermocouple bore extending therethrough from the rear end to the insulative space between the central portion and the locating flange, having the improvement wherein;

• the nozzle comprises a hollow thermocouple tube extending from the thermocouple bore a predetermined distance forwardly along the inner surface of the locating flange to removably receive a thermocouple element extending into the insulative space, the thermocouple tube being spaced a predetermined distance from the outer surface of the central portion of the nozzle
• whereby in the event of a leak of pressurized melt into the insulative space around the central portion of the nozzle, the contact of the hollow thermocouple tube with the locating flange cools the melt which flows into the thermocouple tube around the thermocouple element sufficiently to freeze said melt and prevent leakage through the thermocouple tube.