Thermal seal between manifold and nozzle

1. An injection molding apparatus comprising:

a manifold having a manifold channel, said manifold channel having an inlet for receiving a melt stream of moldable material and an outlet for delivering said melt stream to a nozzle channel of a nozzle;

a sealing element provided between said nozzle and said manifold such that an upstream surface of said sealing element extends beyond an upstream surface of said nozzle in a cold condition, said sealing element including a melt channel for receiving said melt stream from said outlet of said manifold channel and delivering said melt stream to said nozzle channel; and

a mold cavity for receiving said melt stream from said nozzle channel, said nozzle channel communicating with said mold cavity;

wherein said sealing element has a higher thermal expansion coefficient than both said nozzle and said manifold.

2. An injection molding apparatus as claimed in claim 1 , wherein a recess is formed in the upstream surface of said nozzle, said recess being sized to receive said sealing element.

3. An injection molding apparatus as claimed in claim 2 , wherein said melt channel of said sealing element provides a continuous path between said nozzle channel and said outlet of said manifold.

4. An injection molding apparatus as claimed in claim 1 , wherein said sealing element abuts said manifold at an operating temperature to provide a seal between said sealing element and said manifold.

5. An injection molding apparatus as claimed in claim 4 , wherein said sealing element is comprised of copper.

6. An injection molding apparatus as claimed in claim 4 , wherein said sealing element is comprised of beryllium copper.

7. An injection molding apparatus as claimed in claim 4 , wherein said sealing element is comprised of brass.

8. An injection molding apparatus as claimed in claim 1 , wherein a first recess is provided in an outlet surface of said manifold and a second recess is provided in the upstream surface of said nozzle, said first recess and said second recess being aligned to receive said sealing element.

9. An injection molding apparatus as claimed in claim 8 , wherein in a cold condition, a clearance is provided between said sealing element and an offset surface of said first recess.

10. An injection molding apparatus as claimed in claim 9 , wherein at an operating temperature said sealing element abuts said offset surface of said first recess to provide a seal between said sealing element and said manifold.

11. An injection molding apparatus as claimed in claim 10 , wherein said sealing element is comprised of copper.

12. An injection molding apparatus as claimed in claim 10 , wherein said sealing element is comprised of beryllium copper.

13. An injection molding apparatus as claimed in claim 10 , wherein said sealing element is comprised of brass.

14. An injection molding apparatus comprising:

a manifold having a manifold channel;

a nozzle having a nozzle channel in fluid communication with said manifold channel;

a sealing element provided between said nozzle and said manifold, said sealing element including a melt channel in fluid communication with said manifold channel and said nozzle channel;

wherein said manifold includes a first recess provided in an outlet surface thereof for receiving said sealing element, said melt channel of said sealing element being aligned with said nozzle channel and said manifold channel; and

wherein said sealing element has a higher thermal expansion coefficient than both said nozzle and said manifold.

15. An injection molding apparatus as claimed in claim 14 , wherein in a cold condition a clearance is provided between a manifold contacting surface of said nozzle and said sealing element.

16. An injection molding apparatus as claimed in claim 15 , wherein in an operating condition a seal is provided between said sealing element and an upstream surface of said nozzle.

17. An injection molding apparatus as claimed in claim 16 , wherein said sealing element is comprised of copper.

18. An injection molding apparatus as claimed in claim 16 , wherein said sealing element is comprised of beryllium copper.

19. An injection molding apparatus as claimed in claim 16 , wherein said sealing element is comprised of brass.

20. An injection molding apparatus as claimed in claim 15 , wherein said sealing element includes threads located on at least a portion of an outer surface thereof, said threads of said sealing element for mating with a threaded inner surface of said first recess.

21. An injection molding apparatus comprising:

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

a manifold plug provided in said manifold, said manifold plug having a manifold plug channel formed therein, said manifold plug channel having an inlet for receiving said melt stream from said manifold channel and an outlet for delivering said melt stream to a nozzle channel of a nozzle; and

a mold cavity for receiving said melt stream from said nozzle channel, said nozzle channel communicating with said mold cavity through a mold gate;

wherein said manifold plug has a higher thermal expansion coefficient than both said nozzle and said manifold.

22. An injection molding apparatus as claimed in claim 21 , wherein in a cold condition, a clearance is provided between a lower edge of said manifold plug and a manifold contacting surface of said nozzle.

23. An injection molding apparatus as claimed in claim 22 , wherein in an operating condition said manifold plug abuts said manifold contacting surface of said nozzle to provide a seal between said manifold plug and said nozzle.

24. An injection molding apparatus as claimed in claim 23 , wherein said manifold plug is comprised of copper.

25. An injection molding apparatus as claimed in claim 23 , wherein said manifold plug is comprised of beryllium copper.

26. An injection molding apparatus as claimed in claim 23 , wherein said manifold plug is comprised of brass.

27. An injection molding apparatus comprising:

a manifold having a manifold channel, said manifold channel having an inlet for receiving a melt stream of moldable material under pressure and an outlet;

a nozzle having a nozzle body and a nozzle head, said nozzle head being located adjacent an outlet surface of said manifold, said nozzle having a nozzle channel for receiving said melt stream from said outlet of said manifold channel; and

a mold cavity for receiving said melt stream from said nozzle channel, said nozzle channel communicating with said mold cavity through a mold gate;

wherein at least a portion of said nozzle head has a higher thermal expansion coefficient than both said nozzle body and said manifold.

28. An injection molding apparatus as claimed in claim 27 , wherein in a cold condition a clearance is provided between said nozzle head and an outlet surface of said manifold.

29. An injection molding apparatus as claimed in claim 28 , wherein in an operating condition said nozzle head abuts said outlet surface of said manifold to provide a seal between said nozzle head and said manifold.

30. An injection molding apparatus as claimed in claim 29 , wherein said nozzle head is integral with said nozzle body.