Apparatus and Method for a Liquid Cooled Shield for Improved Piercing Performance

• US 20090230095A1
• Filed: 09/29/2008
• Published: 09/17/2009
• Est. Priority Date: 03/12/2008
• Status: Active Grant

• Current Assignee: Hypertherm Incorporated
• Original Assignee: Hypertherm Incorporated
• Inventors: Liebold, Stephen M., Lindsay, Jon W., Currier, Brian J.
• Granted Patent: US 8,389,887 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: B23K 9/296 using non-consumable electrodes
• CPC Class Codes: F28F 3/12 Elements constructed in the shape of a hollow panel, e.g. with channels F28D1/02, F28D1/03 take precedence
• CPC Class Codes: H05H 1/34 Details, e.g. electrodes, nozzles
• CPC Class Codes: H05H 1/3457 Nozzle protection devices

Abstract

A shield for a plasma arc torch that pierces and cuts a metallic workpiece producing a splattering of molten metal directed at the torch, the shield protecting consumable components of the plasma arc torch from the splattering molten metal. The shield can include a body, a first surface of the body configured to be contact-cooled by a gas flow, a second surface of the body configured to be contact-cooled by a liquid flow, and a seal assembly configured to be secured to the body and disposed relative to the second surface configured to retain the liquid flow contact-cooling the second surface.

Claims

1. A retaining cap for a plasma arc torch comprising:

an outer component having an interior surface and an exterior surface which defines, at least in part, a first liquid coolant channel;

an inner component circumferentially disposed within the outer component and having an exterior surface and an interior surface which defines, at least in part, a second liquid coolant channel;

a gas flow channel defined at least in part by the interior surface of the outer component and the exterior surface of the inner component; and

a port located at an end of the gas flow channel between the interior surface of the outer component and the exterior surface of the inner component.

2. The retaining cap of claim 1 wherein the first liquid coolant channel is in fluid communication with the second liquid coolant channel.

3. The retaining cap of claim 1 wherein the first liquid coolant channel is a return flow of liquid coolant.

4. The retaining cap of claim 1 wherein the second liquid coolant channel is a supply flow of liquid coolant.

5. The retaining cap of claim 1 wherein the gas flow channel supplies a shield gas to a workpiece.

6. The retaining cap of claim 1 wherein the interior surface of the inner component comprises a sealing assembly that seals liquid coolant relative to a plasma arc torch body.

7. The retaining cap of claim 1 wherein the interior surface of the inner component is secured relative to a nozzle of the plasma arc torch.

8. The retaining cap of claim 1 wherein the interior surface of the inner component and a plasma arc torch body define, at least in part, the second liquid coolant channel.

9. The retaining cap of claim 1 wherein the exterior surface of the outer component and an outer retaining cap of the plasma arc torch define, at least in part, the first liquid coolant channel.

20. A plasma arc torch system comprising:

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

an electrode;

a nozzle disposed relative to the electrode to define the plasma chamber; and

the retaining cap of claim 1, secured relative to the nozzle.

10. A shield retaining cap for retaining a shield to a plasma arc torch comprising:

an outer component having an interior surface and an exterior surface;

an inner component circumferentially disposed within the outer component and having an interior surface and exterior surface; and

a liquid coolant channel comprising;

a first portion of the liquid coolant channel defined, at least in part, by a portion of the interior surface of the inner component;

a second portion of the liquid coolant channel defined, at least in part, by the exterior surface of the inner component and the interior surface of the outer component; and

a port between the exterior surface of the inner component and the interior surface of the outer component and disposed at an end of at least one of the outer component or the inner component.

11. The shield retaining cap of claim 10 wherein the port is disposed at an end of the liquid coolant channel.

12. The shield retaining cap of claim 10 wherein the liquid coolant channel directs a coolant on to a shield.

13. The shield retaining cap of claim 10 wherein the first portion of the liquid coolant channel is a coolant supply flow.

14. The shield retaining cap of claim 10 wherein the second portion of the liquid coolant channel is a coolant return flow.

15. The shield retaining cap of claim 10 wherein at least one of the inner component or the outer component is secured relative to a shield.

16. The shield retaining cap of claim 10 wherein the interior surface of the inner component and an inner retaining cap define at least in part, the first portion of the liquid coolant channel.

21. The plasma arc torch system of claim 20 further comprising a shield disposed relative to the nozzle and the shield retaining cap of claim 10 secured relative to the shield.

17. A retaining cap for a plasma arc torch comprising:

a shell having an exterior surface that defines, at least in part, a first liquid coolant channel;

a liner circumferentially disposed within the shell and having an interior surface that defines, at least in part, a second liquid coolant channel; and

a gas flow channel defined at least in part by and located between the shell and the liner.

18. A shield retaining cap for a plasma arc torch comprising:

a shell;

a liner disposed circumferentially within an interior surface of the shell; and

a liquid coolant channel comprising;

a first portion of the liquid coolant channel defined, at least in part, by an interior surface of the liner; and

a second portion of the liquid coolant channel defined, at least in part, by a portion of the interior surface of the shell and, at least in part, by a portion of an exterior surface of the liner.

19. A method for cooling a plasma arc torch comprising:

directing a liquid coolant to an electrode;

directing the liquid coolant to a nozzle through a first liquid coolant channel defined, at least in part, by a first retaining cap; and

directing the liquid coolant from the nozzle to a shield through a second liquid coolant channel defined, at least in part, by a second retaining cap.

22. A shield retaining cap for a plasma arc torch comprising:

a substantially cylindrical body dimensioned to receive a shield of the plasma arc torch;

a liquid coolant channel defined by the substantially cylindrical body wherein the liquid coolant channel comprises a return path and a supply path which directs a coolant to impinge a circumferentially extending portion of the shield.

23. The shield retaining cap of claim 22 wherein the temperature of the coolant impinging the shield is consistent at each point along the circumferentially extending portion of the shield.

24. The shield retaining cap of claim 22 wherein the substantially cylindrical body comprises a substantially cylindrical outer component and a substantially cylindrical inner component disposed within the outer component wherein the supply path of the liquid coolant channel is formed at least in part by an interior surface of the substantially cylindrical inner component and wherein the return path of the liquid coolant channel is formed at least in part by an exterior surface of the substantially cylindrical inner component and an interior surface of the substantially cylindrical outer component.