Composite Consumables for a Plasma Arc Torch

• US 20140021175A1
• Filed: 08/09/2012
• Published: 01/23/2014
• Est. Priority Date: 07/19/2012
• Status: Active Grant

• Current Assignee: Hypertherm Incorporated
• Original Assignee: Hypertherm Incorporated
• Inventors: Chen, Carey, Sanders, Nicholas
• Granted Patent: US 10,098,217 B2
• Time in Patent Office: Days
• US Class Current: 219/121.49
• CPC Class Codes: H05H 1/34 Details, e.g. electrodes, nozzles
• CPC Class Codes: H05H 1/3421 Transferred arc or pilot arc mode
• CPC Class Codes: H05H 1/3442 Cathodes with inserted tip
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

An electrode is provided for use in a plasma arc torch. The electrode includes a body having a forward portion, a middle portion and an aft portion. The forward portion includes an electrode tip comprising a conductive first material, wherein the electrode tip includes: 1) a pilot contact region for initiating a pilot arc across the nozzle and 2) an emitter. The middle portion comprises a second material and defines a proximal end for mating with the forward portion and a distal end for mating with the aft portion. The material density of the second material is at least half of the material density of the first material. The electrode also includes an electrically conductive path extending from the forward portion to the aft portion of the body.

Claims

1. An electrode for use in a plasma arc torch, in which the electrode is disposed relative to a nozzle to form a plasma chamber, the electrode comprising:

a body having a forward portion, a middle portion and an aft portion,

the forward portion including an electrode tip comprising a conductive first material, wherein the electrode tip includes;

     1) a pilot contact region for initiating a pilot arc across the nozzle and 2) an emitter;

the middle portion comprising a second material, the middle portion defining a proximal end for mating with the forward portion and a distal end for mating with the aft portion, wherein the material density of the second material is at least half of the material density of the first material; and

an electrically conductive path extending from the forward portion to the aft portion of the body.

2. The electrode of claim 1, wherein the first material comprises copper or silver.

3. The electrode of claim 1, wherein the second material comprises at least one of aluminum, brass, nickel, or stainless steel.

4. The electrode of claim 1, wherein the aft portion comprises a third material.

5. The electrode of claim 4, wherein the third material is substantially non-conductive.

6. The electrode of claim 1, wherein the aft portion comprises the second material.

7. The electrode of claim 1, wherein the electrode tip is cooled by a flow of a pressurized gas external to the electrode.

8. The electrode of claim 1, wherein the first material is copper and the second material is aluminum.

9. The electrode of claim 1, wherein the length of the forward portion comprises about 25% of the length of the electrode.

10. The electrode of claim 1, wherein the forward portion is press fit into the proximal end of the middle portion.

11. The electrode of claim 1, wherein the aft portion is press fit into the distal end of the middle portion.

12. The electrode of claim 1, wherein a mating surface of the forward portion and a first mating surface of the middle portion are in direct contact with each other and form a hermetic seal.

13. The electrode of claim 1, wherein a mating surface of the aft portion and a second mating surface of the middle portion are in direct contact with each other and form a hermetic seal.

14. The electrode of claim 12, wherein the mating surface of the forward portion or the first mating surface of the middle portion is non-planar.

15. The electrode of claim 13, wherein the mating surface of the aft portion or the second mating surface of the middle portion is non-planar.

16. The electrode of claim 1, wherein the forward portion, the aft portion and the middle portion are manufactured as separate pieces.

17. The electrode of claim 1, wherein the density of the first material is at least three times greater than the density of the second material.

18. The electrode of claim 4, wherein the density of the third material is less than the density of at least the first material or second material.

19. The electrode of claim 1, wherein the plasma arc torch comprises a contact start plasma arc torch.

20. The electrode of claim 1, wherein the aft portion includes a pneumatic reaction region for receiving a biasing flow of a pressurized gas.

28. The electrode of claim 1, wherein the first conductive material comprises copper and the second conductive material comprises aluminum.

21. An electrode for use in a plasma arc torch, the electrode comprising:

an elongated forward portion, defining a proximal end and a distal end, configured to provide an electrically conductive path from the distal end to the proximal end, the forward portion comprising a first conductive material with a first density;

a ring-shaped aft portion, defining a hollow center, configured to substantially surround a portion of the forward portion when the forward portion is located inside of the hollow center, the aft portion comprising a second conductive material with a second density, wherein the second density is at least two times less than the density of the first material; and

an emitter disposed in the proximal end of the forward portion.

22. The electrode of claim 21, wherein the ring-shaped aft portion includes a pneumatic reaction region for receiving a biasing flow of a pressurized gas.

23. The electrode of claim 21, wherein the ring-shaped aft portion includes at least one fluid passageway for allowing passage of a gas therethrough.

24. The electrode of claim 21, further comprising:

a contact element located at the distal end of the forward portion; and

a resilient element located between the contact element and the ring-shaped aft portion while physically contacting the forward portion, the resilient element configured for biasing the ring-shaped aft portion and the forward portion away from the contact element.

25. The electrode of claim 24, wherein the contact element comprises a third material.

26. The electrode of claim 24, wherein the resilient element passes substantially all of a pilot arc current between a power supply and the forward portion via the contact element during a pilot arc operation of the plasma arc torch.

27. The electrode of claim 24, wherein the resilient element passes at least a portion of a transferred arc current between a power supply and the forward portion via the contact element during a transferred arc operation of the plasma arc torch.

29. A plasma arc torch comprising:

an electrode comprising at least a forward portion and an aft portion, wherein;

the forward portion including an electrode tip comprising a conductive first material, the electrode tip including;

     1) a pilot contact region for initiating a pilot arc and

     2) an emitter; and

the aft portion comprising a second material, the material density of the second material being at least half of the material density of the first material; and

a nozzle mounted relative to the electrode, the nozzle and the electrode defining a plasma chamber.

30. The plasma arc torch of claim 29, wherein the electrode tip is cooled by a plasma flow through the plasma chamber.

31. The plasma arc torch of claim 29, wherein the electrode further comprises a third portion coupled to a distal end of the aft portion, the third portion including a pneumatic reaction region for receiving a plasma flow.

32. The plasma arc torch of claim 29, wherein the nozzle comprises at least a tip portion and a body portion, the tip portion comprising the conductive first material and the body portion comprising the second material.

33. A method of manufacturing an electrode usable in a plasma arc torch, the method comprising:

selecting a first conductive material having a first density and a second conductive material having a second density, wherein the second density is at least two times greater than the density of first material;

forming an elongated aft portion from the first conductive material, the elongated aft portion defining a proximal end and a distal end;

forming an elongated forward portion from the second conductive material such that the elongated forward portion is coupled to the proximal end of the aft portion, and locating an emitter in the forward portion.

34. The method of manufacturing of claim 33, further comprising:

selecting a third material having a third density; and

forming a third portion from the third material such that the third portion is coupled to the distal end of the aft portion, wherein the third portion includes a pneumatic reaction region for receiving a biasing flow of a pressurized gas.

35. A method of manufacturing an electrode usable in a plasma arc torch, the method comprising:

selecting a first conductive material having a first density and a second conductive material having a second density, wherein the second density is at least two times greater than the density of first material;

forming a ring-shaped aft portion from the first conductive material, the ring-shaped aft portion defining a hollow center;

forming an elongated forward portion from the second conductive material, the elongated forward portion defining a proximal end and a distal end;

fitting the elongated forward portion through the hollow center of the ring-shaped aft portion such that the ring-shaped aft portion substantially surrounds at least a portion of the forward portion; and

locating an emitter in the proximal end of the forward portion.

36. The method of manufacturing of claim 35, further comprising:

locating a contact element at the distal end of the forward portion; and

locating a resilient element between the contact element and the ring-shaped aft portion

while the resilient element physically contacts the forward portion.