Generating discrete gas jets in plasma arc torch applications

• US 20060289398A1
• Filed: 05/11/2006
• Published: 12/28/2006
• Est. Priority Date: 05/11/2005
• Status: Active Grant

• Current Assignee: Hypertherm Incorporated
• Original Assignee: Hypertherm Incorporated
• Inventors: Duan, Zheng, Liebold, Stephen M., Lindsay, Jon W., Cook, David Jonathan
• Granted Patent: US 7,598,473 B2
• Time in Patent Office: Days
• US Class Current: 219/121.500
• CPC Class Codes: B23K 10/00 Welding or cutting by means of a plasma
• CPC Class Codes: H05H 1/34 Details, e.g. electrodes, nozzles
• CPC Class Codes: H05H 1/3405 Arrangements for stabilising or constricting the arc, e.g. by an additional gas flow
• CPC Class Codes: H05H 1/3457 Nozzle protection devices
• CPC Class Codes: H05H 1/3468 Vortex generators
• CPC Class Codes: H05H 1/3478 Geometrical details

Abstract

The invention is generally directed to a nozzle for a plasma torch, the nozzle having a rear portion that defines at least a portion of a plasma chamber and a front portion that includes a first end and a second end. The first end is adjacent the rear portion, and the second end defines a plasma exit portion. One or more fluid passageways are disposed within the front portion and extend from the first end to the second end. The fluid passageways have passageway exit portions that provide one or more discrete jets of a secondary fluid to surround a plasma jet that is ejected from the plasma exit portion. Features of the invention include faster cutting, thicker workpiece piercing capability, reduced noise, improved arc stability, and increased consumable life, all of which improve productivity associated with plasma arc torch workpiece processing.

Claims

1. A nozzle for a transferred arc plasma torch, the nozzle comprising:

a rear portion defining at least a portion of a plasma chamber; and

a front portion including a first end disposed adjacent to the rear portion, a second end defining a plasma exit portion, and one or more fluid passageways disposed within the front portion, each of the one or more fluid passageways extending from the first end to the second end and having a passageway exit portion that provides one or more discrete jets of a secondary fluid disposed about a plasma jet.

2. The nozzle of claim 1, wherein each of the one or more fluid passageways includes a passageway exit portion disposed substantially adjacent the plasma exit portion.

3. The nozzle of claim 2, wherein the one or more fluid passageways each define a fluid path that generates substantially parallel flow between the secondary fluid exiting the passageway exit portion and the plasma jet.

4. The nozzle of claim 2, wherein the one or more fluid passageways each define a fluid path that generates converging angular flow of the secondary fluid exiting the passageway exit portion relative to the plasma jet.

5. The nozzle of claim 2, wherein the one or more fluid passageways each define a fluid path that generates diverging angular flow of the secondary exiting the passageway exit portion relative to the plasma jet.

6. The nozzle of claim 1, wherein the one or more discrete jets comprise a plurality of discrete jets to surround the plasma jet.

7. The nozzle of claim 1, wherein the rear portion and the front portion are integrally formed.

8. The nozzle of claim 1, wherein the discrete jets reduce an interaction between an ambient fluid and the plasma jet.

9. The nozzle of claim 1, wherein the one or more fluid passageways comprise a plurality of fluid passageways, the plurality of fluid passageways forming a radial arrangement about the plasma exit portion.

10. The nozzle of claim 1, wherein the front portion further includes a relief flat disposed along a side of each of the one or more fluid passageways to increase an amount of the secondary fluid flow that enters into the one or more fluid passageways.

11. The nozzle of claim 1, wherein the one or more fluid passageways impart a swirling motion to the secondary fluid.

12. The nozzle of claim 1, wherein the rear portion further includes a securing mechanism for securing the nozzle to a plasma torch body.

13. The nozzle of claim 1, wherein the front and rear portions are formed from an electrically conductive material.

14. The nozzle of claim 1, further comprising a circumscribing component defining an interior surface and an exterior surface, the circumscribing component mounted relative to the front portion such that at least a portion of the interior surface cooperates with the front portion to form the one or more fluid passageways.

15. The nozzle of claim 14, wherein the interior surface of the circumscribing component defines a portion of one or more discrete fluid passageways that correspond to the one or more fluid passageways disposed on the front portion of the nozzle.

16. The nozzle of claim 1, further comprising a circumscribing component defining an interior surface and an exterior surface, the circumscribing component mounted relative to the front portion of the nozzle such that at least a portion of the interior surface cooperates with the front portion to form a secondary fluid passageway.

17. The nozzle of claim 16, wherein a secondary fluid flows through the secondary fluid passageway independently of a plasma gas that flows through the plasma chamber and a shielding gas that flows over the exterior surface of the circumscribing component.

18. The nozzle of claim 1, wherein each of the one or more fluid passageways provide a discrete path for the secondary fluid.

19. (Canceled)

20. A shield for protecting a nozzle of a transferred arc plasma torch, the shield comprising:

a shield body defining a shield exit portion and having an exterior portion and an interior portion, the interior portion including an angular kink for diverting a fluid into a fluid passageway disposed within the nozzle.

21. The shield of claim 20, wherein the interior portion of the shield body includes one or more angular kinks to divert a fluid into one or more corresponding fluid passageways disposed within the nozzle.

22. A shield for a transferred arc plasma torch, the shield comprising:

a shield body defining a shield exit portion and having an exterior portion and an interior portion, the interior portion including one or more fluid passageways each having a passageway exit portion that provide one or more discrete jets of a secondary fluid disposed about a plasma jet.

23. A torch tip for a transferred arc plasma torch, the torch tip having a longitudinal axis and comprising:

a nozzle comprising a rear portion defining at least a portion of a plasma chamber, and a front portion including a first end disposed adjacent to the rear portion, a second end defining a plasma exit portion, and one or more fluid passageways disposed within the front portion, each of the one or more fluid passageways extending from the first end to the second end and having passageway exit portions that provide discrete jets of a secondary fluid disposed about a plasma jet; and

a shield comprising a shield body defining a shield exit portion and having an exterior portion and an interior portion, the shield being mounted in a spaced relation to the nozzle relative to the longitudinal axis of the torch tip such that a secondary passageway is formed between the shield and the nozzle.

24. The torch tip of claim 23, wherein each of the one or more fluid passageways disposed within the front portion of the nozzle include a passageway exit portion disposed substantially adjacent the plasma exit portion of the nozzle.

25. A method comprising:

generating a plasma jet that exits a transferred arc plasma torch from a plasma exit portion of a nozzle detachably mounted to a torch body; and

forming one or more discrete jets of a secondary fluid from passageway exit portions of one or more fluid passageways disposed at least in part on the nozzle or a shield mounted on the torch substantially coaxially with the nozzle, wherein the one or more discrete jets are disposed about a longitudinal axis of the plasma jet.

26. A torch tip for a transferred arc plasma torch, the torch tip comprising:

a nozzle including a rear portion defining at least a portion of a plasma chamber, and a front portion including a first end disposed adjacent to the rear portion, a second end defining a plasma exit portion, and at least a portion of one or more discrete fluid pathways disposed on the front portion and extending from the first end to the second end; and

a circumscribing component defining an interior surface and an exterior surface, the circumscribing component mounted relative to the nozzle such that at least a portion of the interior surface cooperates with the front portion of the nozzle to form one or more fluid passageways for generating one or more discrete jets of a secondary fluid.

27. The torch tip of claim 26, wherein the interior surface defines a portion of one or more discrete fluid passageways that correspond to the one or more discrete fluid pathways disposed on the front portion of the nozzle.

28. The torch tip of claim 26, further comprising a sealing component disposed between the nozzle and the interior surface of the circumscribing component.

29. A torch tip for a transferred arc plasma torch, the tip comprising:

a nozzle comprising a rear portion defining at least a portion of a plasma chamber, and a front portion defining a plasma exit portion,

a means for generating one or more discrete jets of a secondary fluid disposed about a plasma jet exiting the torch from the plasma exit portion; and

a circumscribing means mounted relative to the nozzle and defining a fluid exit portion permitting the discrete jets to exit the torch tip.

30. A transferred arc plasma torch comprising:

an electrode having an exterior surface that defines a portion of a plasma chamber;

a nozzle detachably mounted to a torch body, the nozzle including a rear portion defining at least a portion of the plasma chamber and a front portion defining a plasma exit portion,

a means for generating one or more discrete jets of a secondary fluid, the jets disposed about a plasma jet exiting the plasma exit portion;

a shield mounted to a retaining cap that is secured to the torch body, the shield defining a shield exit portion substantially aligned with the plasma exit portion to permit the plasma jet and the discrete jets to exit the torch; and

a swirl ring mounted relative to the torch body for imparting a swirling motion to at least one of a plasma gas, a secondary gas, or a tertiary gas within the torch.