Plasma arc torch having an electrode with internal passages

• US 7,375,302 B2
• Filed: 11/16/2004
• Issued: 05/20/2008
• Est. Priority Date: 11/16/2004
• Status: Expired due to Fees

• Current Assignee: Hypertherm Incorporated
• Original Assignee: Hypertherm Incorporated
• Inventors: Cook, David J., Altobelli, Bruce P., Bouthillier, David L., Twarog, Peter J., Hackett, Charles M.
• Primary Examiner(s): Hoang; Tu Ba
• Assistant Examiner(s): Ralis; Stephen J.
• Application Number:
  US10/989,729
• Publication Number:
  US 20060102598A1
• Time in Patent Office: 1,281 Days
• Field of Search: 219/121.39, 219/121.43, 219/121.44, 219/121.48, 219/121.5, 219/121.52, 219/121.59
• US Class Current: 219/121.52
• CPC Class Codes: B23K 10/02 Plasma welding
• CPC Class Codes: H05H 1/34 Details, e.g. electrodes, nozzles
• CPC Class Codes: H05H 1/3436 Hollow cathodes with internal coolant flow
• CPC Class Codes: H05H 1/3442 Cathodes with inserted tip
• CPC Class Codes: H05H 1/3478 Geometrical details

Abstract

An electrode for a plasma arc cutting torch which minimizes the deposition of high emissivity material on the nozzle, reduces electrode wear, and improves cut quality. The electrode has a body having a first end, a second end in a spaced relationship relative to the first end, and an outer surface extending from the first end to the second end. The body has an end face disposed at the second end. The electrode also includes at least one passage extending from a first opening in the body to a second opening in the end face.

Claims

1. An electrode for a plasma arc torch, the electrode comprising:

a body having a first end and a second end in a spaced relationship relative to the first end, the body having an end face disposed at the second end, the end face defining an edge, wherein during operation a first gas flow flowing about the body, from the first end to the second end;

an insert with an emission surface, the insert disposed in the second end of the body, the insert defining a perimeter, wherein during operation of the electrode a plasma arc emission is confined within the perimeter of the insert; and

at least one passage extending through the body, the at least one passage dimensioned to divert a first portion of the first gas flow to create a second gas flow, the second gas flow flowing from a first opening adjacent the second end of the body and exiting a second opening in the end face of the second end of the body, the second opening being located between the perimeter and the edge, wherein during operation a second portion of the first gas flow flowing outside the edge.

2. An electrode for a plasma arc torch, the electrode comprising:

a body having a first end, a second end in a spaced relationship relative to the first end, and an outer surface extending from the first end to the second end, the body having an end face disposed at the second end, the end face defining an edge, wherein during operation of the electrode, a swirling gas flow flowing about the body, from the first end to the second end of the body;

an insert with an emission surface, the insert disposed in the second end of the body, the insert defining a perimeter, wherein during operation of the electrode a plasma arc emission is confined within the perimeter of the insert; and

at least one axially and radially directed passage formed in the body extending from a first opening in the outer surface of the body to a second opening in the end face of the second end of the body, second opening being inside the edge and outside the perimeter, the at least one passage is dimensioned to direct a second gas flow to exit the second opening, wherein during operation of the electrode the swirling gas flow flowing outside the edge.

3. An electrode for a plasma arc torch, the electrode comprising:

a body having a first end, a second end in a spaced relationship relative to the first end, an end face disposed at the second end, the end face defining an edge, and an outer surface extending from the first end to the second end, the body defining a bore disposed in the second end of the body;

an insert with an emission surface, the insert disposed in the bore, the insert defining a perimeter, wherein during operation of the electrode a plasma arc emission is confined within the perimeter of the insert; and

at least one passage extending from a first opening in the body to a second opening adjacent the bore in the second end of the body, wherein the second opening is located between the edge and the perimeter and is substantially coplanar with the emission surface of the insert.

4. A plasma arc torch for marking or cutting a workpiece, the plasma arc torch comprising:

a torch body including a plasma flow path for directing a plasma gas to a plasma chamber in which a plasma arc is formed; and

an electrode mounted in the torch body, the electrode comprising an electrode body having a first end, a second end in a spaced relationship relative to the first end, an outer surface extending from the first end to the second end, and at least one passage, the electrode body having an end face disposed at the second end of the electrode body, the end face defining an edge, wherein during operation of the plasma arc torch, a swirling gas flow flowing about the body, from the first end to the second end, an insert with an emission surface, the insert disposed in the second end of the electrode body, the insert defining a perimeter, wherein during operation of the electrode a plasma arc emission is confined within the perimeter, and the at least one passage extending from a first opening in the electrode body to a second opening in the end face at the second end of the electrode body, wherein the at least one passage is dimensioned to divert a first portion of the swirling gas flow to create a second gas flow that enters the first opening and exits the second opening, the second opening being between the perimeter and the edge, wherein during operation of the plasma arc torch a second portion of the swirling gas flow flowing outside the edge.

5. The plasma arc torch of claim 4, comprising a nozzle mounted relative to the electrode in the torch body to define the plasma chamber.

6. The plasma arc torch of claim 4, wherein the at least one passage is located at an acute angle relative to a longitudinal axis of the electrode body.

7. The plasma arc torch of claim 4, comprising a cap located at the second end of the electrode body, wherein the at least one passage is defined by the cap and the electrode body.

8. The plasma arc torch of claim 4, wherein the electrode body comprises at least two components that form the at least one passage when the at least two components are assembled.

9. The plasma arc torch of claim 4, wherein the at least one passage is a plurality of passages.

10. The plasma arc torch of claim 9, wherein the plurality of passages are mutually equally angularly spaced around a diameter of the electrode body.

11. The plasma arc torch of claim 9, wherein the plurality of passages each extend from a respective first opening in the electrode body to a respective second opening in the second end of the electrode body.

12. A plasma arc torch component configured to operate in conjunction with a generally elongated electrode having an insert in one end thereof, the insert defining a perimeter and having an emission surface for emitting a plasma arc, such that during operation of the electrode a plasma arc emission is substantially confined within the perimeter of the insert, the component comprising:

a body having a first end and a second end, and an outer surface extending from the first end to the second end, the second end having an end face, the end face defining an edge, at least one passage extending through the body and having a first opening and a second opening, the second opening located outside the perimeter and inside the edge, wherein during operation a swirling first gas flow flows about the outer surface and outside the edge and a second gas flow flows through the at least one passage.

13. The component of claim 12 wherein the at least one passage is a tapered orifice.

14. The component of claim 12 comprising a nozzle mounted relative to the body and the electrode in a torch body.

15. A torch tip for a plasma arc torch, the plasma arc torch having a hollow torch body which includes a plasma chamber in which a plasma arc is formed, the torch tip comprising:

a nozzle having an interior surface; and

an electrode mounted relative to the nozzle in the torch body to define the plasma chamber, the electrode comprising an electrode body having a first end, a second end in a spaced relationship relative to the first end, an outer surface extending from the first end to the second end to allow a swirling gas flow between the electrode body and the interior surface of the nozzle, and at least one passage for diverting a first portion of the swirling gas flow to create a second gas flow through the body of the electrode, the electrode body having an end face at the second end of the electrode body, the end face defining an edge, an insert with an emission surface, the insert disposed in the second end of the electrode body, the insert defining a perimeter wherein during operation of the torch tip a plasma arc emission is confined within the perimeter, and the at least one passage extending from a first opening in the electrode body to a second opening in the end face at the second end of the electrode body, the second opening being inside the edge and outside the perimeter, the second opening is positioned to direct the second gas flow to exit the second opening substantially adjacent the insert, the interior surface of the nozzle is positioned to direct a second portion of the swirling gas flow flowing outside the edge.

16. The torch tip of claim 15, comprising a shield.

17. An electrode for a plasma arc torch, the electrode comprising:

a body having a first end, a second end in a spaced relationship relative to the first end, and an outer surface extending from the first end to the second end, the body having an end face disposed at the second end, the end face defining an edge;

an insert with an emission surface, the insert disposed at the second end of the body, the insert defining a perimeter, wherein during operation of the electrode a plasma arc emission is confined within the perimeter of the insert; and

at least one passage extending through the body from a first opening in the body to a second opening in the end face, wherein the at least one passage is dimensioned to divert a first portion of a swirling gas flow to create a second gas flow that enters the first opening and exits the second opening, the second opening being located between the perimeter and the edge, wherein during operation of the electrode the second portion of the swirling gas flow flowing adjacent the edge and radially outward of the second opening.

18. The electrode of claim 17 wherein the at least one passage is dimensioned to direct the second gas flow comprising an axial velocity component to exit the second opening.

19. The electrode of claim 17 wherein the at least one passage is dimensioned to direct the second gas flow comprising one or more of axial, radial, and tangential velocity components to exit the second opening.

20. The electrode of claim 17 wherein the swirling gas flow and the second gas flow are supplied by the same gas source.

21. The electrode of claim 17 wherein the swirling gas flow comprises a swirl strength and the at least one passage is dimensioned to direct the second gas flow to exit the second opening with an axial velocity component that effects the swirl strength of the first gas flow.

22. The electrode of claim 17 wherein the second gas flow comprises a non-oxidizing gas.

23. An electrode for a plasma arc torch, the electrode comprising:

a body having a first end, a second end in a spaced relationship relative to the first end, and an outer surface extending from the first end to the second end wherein during operation of the electrode a swirling gas flow flowing about the outer surface, the body having an end face disposed at the second end, the end face defining an edge;

an insert with an emission surface, the insert disposed in the second end of the body, the insert defining a perimeter, wherein during operation of the electrode a plasma arc emission is confined within the perimeter of the insert; and

at least one passage extending through the body from a first opening in the body to a second opening in the end face, the at least one passage is dimensioned to divert a first portion of the swirling gas flow to create a second gas flow that enters the first opening and exits the second opening, the second opening located between the perimeter and the edge.

24. The electrode of claim 23 wherein the at least one passage is dimensioned to direct the second gas flow to exit the second opening with one or more of axial, radial, and tangential velocity components.

25. The electrode of claim 23 wherein the swirling gas flow and the second gas flow are supplied by the same gas source.

26. The electrode of claim 23 wherein the second gas flow comprises an axial velocity component.

27. The electrode of claim 23 wherein the at least one passage is dimensioned to direct the second gas flow to exit the second opening with an axial velocity component.

28. The electrode of claim 23 wherein the at least one passage is dimensioned to direct the second gas flow to exit the second opening with an axial velocity component that effects the swirl strength of the swirling gas flow.

29. The electrode of claim 23 wherein the second gas flow comprises a non-oxidizing gas.

30. An electrode for a plasma arc torch, the electrode comprising:

a body having a first end, a second end in a spaced relationship relative to the first end, and an outer surface extending from the first end to the second end, the body having an end face disposed at the second end, the end face defining an edge;

an insert made of an emissive material and defining a perimeter, wherein during operation a plasma arc emission is confined within the perimeter, the insert disposed in the second end of the body, wherein the emissive material is ejected due to use over time; and

means for providing a second gas flow located between the perimeter and the edge to reduce the ejection of emissive material by reducing the swirl strength of a first gas flow in the region of the plasma arc emission.