Injection molding nozzle with recessed terminal

1. A hot runner injection molding nozzle comprising:

a nozzle body having an outer surface, first and second opposed ends, and an inner surface defining a central melt channel extending between the first and second ends;

an electrically conductive heating element coupled to the nozzle body and having at least one end coupled to an external lead element at a terminal connection; and

a terminal housing containing the terminal connection and fastened to the nozzle body, wherein the outer surface of the nozzle body is recessed to define a seat and the terminal housing has a width that is at least partially positioned within the seat; and

a stress relief member fastened to the nozzle body and adapted to retain the external lead element in a position spaced from the terminal connection thereby relieving stress on the terminal connection.

2. The nozzle of claim 1 , wherein the seat and terminal housing are dimensioned so that at least 40% of the volume of the terminal housing is contained in the seat.

3. The nozzle of claim 1 , wherein the seat and terminal housing are dimensioned so that 90% of the volume of the terminal housing is contained in the seat.

4. The nozzle of claim 1 , wherein the electrically conductive heating element is an electrical resistance heater wire surrounded by insulation and embedded in the outer surface of the nozzle body.

5. The nozzle of claim 1 , wherein the electrically conductive heating element extends into the seat.

6. The nozzle of claim 4 , further comprising:

a second external lead element, wherein the resistance heater wire has a portion formed into a U-shaped bend such that two opposite ends thereof are disposed at the terminal connection and each end is coupled to a respective external lead element.

7. The nozzle of claim 6 , wherein end portions of the resistance heater wire extend in parallel into the seat such that the terminal connection is positioned within the seat.

8. The nozzle of claim 6 , wherein the stress relief member is a part of the terminal housing and comprises a pair of protrusions extending from an interior surface of the terminal housing, the protrusions engaging the lead elements and clamping the lead elements against an opposite interior surface of the terminal housing.

9. The nozzle of claim 6 , wherein the stress relief member is separate from the terminal housing and comprises a pair of arcuate retainers dimensioned to retain and clamp the respective lead elements against the outer surface of the nozzle body.

10. A nozzle body assembly for a hot runner injection molding nozzle, the assembly comprising:

a nozzle body having an outer surface, first and second opposed ends, and an inner surface defining a central melt channel extending between the first and second ends, the nozzle body outer surface being recessed to define a seat, the seat having

a bottom wall and

at least three side walls radially-extending from the bottom wall comprising

a pair of spaced side walls and

a third wall connecting the spaced side walls, the third wall defining two openings;

an electrically conductive heating element coupled to the outer surface of the nozzle body and extending into the seat in a direction that is generally parallel to the bottom wall of the seat, the electrically conductive heating element having two ends passing through respective openings in the third wall to be located in the seat; and

two external lead elements, wherein each lead element is attached to a respective end of the electrically conductive heating element to form a terminal connection in the seat.

11. The assembly of claim 10 , further comprising:

a terminal housing at least partially positioned within the seat in the nozzle body, wherein the terminal housing surrounds the terminal connection.

12. The assembly of claim 11 , wherein the seat and terminal housing are dimensioned so that at least 70% of the volume of the terminal housing is contained in the seat.

13. The assembly of claim 11 , wherein the seat and terminal housing are dimensioned so that substantially all of the volume of the terminal housing is contained in the seat.

14. The assembly of claim 10 , further comprising:

a stress relief member attached to the nozzle body, wherein the stress relief member retains the external lead elements in a position against the nozzle body that is spaced from the terminal connection thereby relieving stress on the terminal connection.

15. A hot runner injection molding apparatus, comprising:

a manifold having a manifold melt channel for receiving a melt stream of moldable material;

a hot runner nozzle including,

a nozzle body defining a central melt channel that is in fluid communication with the manifold melt channel, wherein an outer surface of the nozzle body is recessed to define a seat, the seat having a bottom wall and at least two side walls radially-extending from the bottom wall,

an electrically conductive heating element coupled to the outer surface of the nozzle body and having an end portion that extends into the seat generally parallel with the bottom wall of the seat,

an external lead element having an end portion that extends into the seat generally parallel with the bottom wall of the seat, wherein end portions of the heating element and the external lead element are electrically coupled to form a terminal connection within the seat, and

a nozzle tip coupled to a downstream end of the nozzle body; and

a mold cavity in fluid communication with the nozzle tip, wherein the mold cavity receives the melt stream of moldable material from the manifold via the hot runner nozzle.

16. The apparatus of claim 15 , further comprising:

a terminal housing at least partially positioned within the seat in the nozzle body, wherein the terminal housing surrounds the terminal connection.

17. The apparatus of claim 15 , further comprising:

a stress relief member attached to the nozzle body, wherein the stress relief member retains the external lead element in a position against the nozzle body that is spaced from the terminal connection thereby relieving stress on the terminal connection.

18. The apparatus of claim 15 , wherein the at least two side walls of the seat include a pair of spaced side walls, and a third wall connecting the spaced side walls.

19. The apparatus of claim 18 , wherein the third wall includes an opening through which the end portion of the electrically conductive heating element extends into the seat.

20. The apparatus of claim 15 , further comprising:

a second external lead element having an end portion that extends into the seat generally parallel with the bottom wall of the seat, wherein the heating element has two end portions that are electrically coupled to respective end portions of the external lead elements within the seat to form the terminal connection.