Dielectric devices for a plasma arc torch

• US 20070262060A1
• Filed: 12/22/2006
• Published: 11/15/2007
• Est. Priority Date: 05/11/2006
• Status: Active Grant

• Current Assignee: Hypertherm Incorporated
• Original Assignee: Hypertherm Incorporated
• Inventors: Roberts, Jesse A., Kornprobst, Michael F., Cook, David Jonathan
• Granted Patent: US 8,097,828 B2
• Time in Patent Office: Days
• US Class Current: 219/121.500
• CPC Class Codes: H05H 1/34 Details, e.g. electrodes, nozzles
• CPC Class Codes: H05H 1/3457 Nozzle protection devices
• CPC Class Codes: H05H 1/3473 Safety means

Abstract

Apparatus and methods for thermally processing a workpiece include directing a plasma arc to the workpiece and using a dielectric shield or dielectric coating to protect a forward portion (e.g., a torch head) of a plasma arc torch. The dielectric shield or dielectric coating covers a nozzle disposed within the torch head and protects the nozzle from the effects of slag and double arcing. The shield also improves operator visibility due to the spatial relationship between the dielectric shield and the nozzle.

Claims

1. A dielectric shield for a plasma arc torch including a nozzle, at least a portion of the dielectric shield comprising a non-ceramic substrate and a dielectric coating disposed on the non-ceramic substrate, the dielectric shield sized to inhibit protrusion of the nozzle pass an end face of the dielectric shield when attached to the plasma arc torch.

2. The dielectric shield of claim 1 wherein the non-ceramic substrate comprises a metal.

3. The dielectric shield of claim 1 wherein the dielectric coating comprises an anodized material.

4. The dielectric shield of claim 1 wherein the end face of the shield includes the dielectric coating.

5. The dielectric shield of claim 1 wherein the non-ceramic substrate comprises an electrically conductive material.

6. The dielectric shield of claim 1 wherein the anodized material is anodized aluminum.

7. The dielectric shield of claim 1 wherein the shield includes multiple coatings disposed on the non-ceramic substrate.

8. The dielectric shield of claim 7 wherein the multiple coatings are layered.

9. The dielectric shield of claim 5 wherein the dielectric coating is on an interior surface of the shield.

10. The dielectric shield of claim 5 wherein the dielectric coating is applied to an entirety of the shield.

11. The dielectric shield of claim 5 wherein the dielectric coating is applied to an aluminum substrate.

12. The dielectric shield of claim 5 wherein the dielectric coating is on an exterior surface of the shield.

13. The dielectric shield of claim 1 wherein the dielectric coating comprises a ceramic layer.

14. The dielectric shield of claim 1 further comprising:

spring tangs for at least one of connecting or disconnecting the shield from the plasma arc torch.

15. The dielectric shield of claim 1 wherein the shield includes multiple connecting portions.

16. The dielectric shield of claim 1 wherein the shield body includes multiple disconnecting portions.

17. The dielectric shield of claim 1 wherein at least a portion of the shield contacts at least a portion of the nozzle.

18. A torch head for a plasma arc torch for processing a metallic workpiece, the torch head comprising:

a nozzle mounted relative to an electrode in a torch body to define a plasma chamber in which a plasma arc is formed, the nozzle comprising a conductive nozzle body portion and defining a nozzle exit orifice extending therethrough; and

a shield capable of being secured to the torch body such that at least a portion of a surface of the shield directly contacts the nozzle body portion and the shield being sized to inhibit protrusion of the nozzle pass an end face of the shield, the shield at least partially defining a cooling passage for providing a cooling gas to the torch head and comprising a non-ceramic body and a dielectric coating disposed on at least a portion of the non-ceramic body.

19. The torch head of claim 18, wherein the shield includes a metallic body.

20. The torch head of claim 18, wherein the shield comprises an electrically conductive body.

21. The torch head of claim 18, wherein the shield comprises an anodized body.

22. The torch head of claim 21, wherein the anodize body comprises an anodized aluminum body.

23. The torch head of claim 18, wherein the shield electrically isolates the nozzle body portion.

24. The torch head of claim 18, wherein the surface is an interior surface.

25. A torch head for a plasma arc torch for processing a metallic workpiece, the torch tip comprising:

a nozzle mounted relative to an electrode in the torch body to define a plasma chamber in which a plasma arc is formed, the nozzle comprising a conductive nozzle body portion defining a nozzle exit orifice extending therethrough; and

a shield including a non-ceramic portion, a dielectric portion, and an end face portion, the shield inhibiting the nozzle body portion from extending pass the end face and preventing arcing within the torch head when the shield is secured within an arcing distance of the nozzle.

26. The torch head of claim 25, wherein the shield is configured for cooling by a shield gas supplied from the plasma arc torch.

27. The torch head of claim 25, wherein the non-ceramic portion of the shield is electrically conductive.

28. The torch head of claim 25, wherein the non-ceramic portion includes a metal.

29. The torch head of claim 25, wherein the shield comprises an anodized body.

30. The torch head of claim 25, wherein the shield comprises an anodized aluminum body.

31. A nozzle for a plasma arc torch, the nozzle adapted to be mounted relative to an electrode in a torch body to define a plasma chamber, the nozzle comprising:

a hollow nozzle body portion; and

a nozzle head portion in contact with the nozzle body portion and defining a nozzle exit orifice extending therethrough, a surface of the nozzle head portion having multiple coatings disposed thereon, at least one of the multiple coating comprising a dielectric material.

32. The nozzle of claim 31, wherein the dielectric coating is exposed on an exterior surface.

33. The nozzle of claim 31, wherein each of the multiple coatings comprises a dielectric material.

34. The nozzle of claim 31, where the hollow nozzle body portion comprises copper.

35. The nozzle of claim 31, where the nozzle head portion comprises copper.

36. The nozzle of claim 31, where the nozzle head portion comprises at least one of copper or aluminum.

37. A method of protecting a plasma arc torch including an electrode and a nozzle disposed within a torch body the method comprising:

securing a shield including a non-ceramic substrate and a dielectric coating to the torch body between the workpiece and at least a portion of the nozzle; and

cooling the shield with a gas flowing through the torch body.

38. The method of claim 37, wherein the shield includes a metallic, conductive substrate.

39. The method of claim 37, wherein the dielectric coating comprises an anodized material.

40. A method of protecting a plasma arc torch including an electrode, the method comprising:

mounting a nozzle relative to the electrode in a torch body to define a plasma chamber, the nozzle including a nozzle body portion and a nozzle head portion in contact with the nozzle body portion and defining a nozzle exit orifice extending through the nozzle head portion, an exterior surface of the nozzle head portion having a dielectric coating disposed thereon.

cooling the nozzle with a gas flowing over a portion of the exterior surface of the nozzle head portion.

41. The method of claim 40, wherein the nozzle head portion comprises an anodized metal.