Plasma cutting system with efficient components

Patent metadata

Field	Value
Publication number	US-9908195-B2
Application number	US-201514610135-A
Country	US
Kind code	B2
Filing date	Jan 30, 2015
Priority date	May 30, 2014
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

A plasma cutting system is provided. The system includes a power source configured to generate a plasma arc, and a plasma arc torch connected to the power source for delivering the plasma arc to a workpiece. The plasma arc torch defines a multi-function fluid flow path for sustaining the plasma arc and cooling the plasma arc torch such that the plasma cutting system has a power-to-gas flow ratio of at least 2 kilowatts per cubic feet per minute (KW/cfm). The power-to-gas flow ratio comprises a ratio of power of the generated plasma arc to a total gas flow supplied to the plasma arc torch.

First claim

What is claimed is:

1. A plasma cutting system comprising:
an enclosure including:
a power source located in the enclosure and configured to generate a plasma arc; and
a compressor located in the enclosure and operably connected to the power source for generating a gas supply to the plasma cutting system;

a plasma arc cutting torch connected to the power source for delivering the plasma arc to cut a workpiece at a distal end of the torch, the torch comprising a swirl ring, an electrode, a nozzle, and a plasma chamber defined by the electrode and the nozzle; and
a circumferential seal formed between the electrode and the swirl ring of the torch, the circumferential seal configured to prevent the gas supply from traveling in a reverse flow direction toward a proximal end of the torch away from the workpiece,
wherein the plasma arc cutting torch further comprises a second circumferential seal formed between the swirl ring and a retaining cap to engage an external surface of the swirl ring to an internal surface of the retaining cap,
wherein the plasma arc cutting torch defines a multi-function fluid flow path that receives the gas supply from the compressor for sustaining the plasma arc and cooling the plasma arc cutting torch, the multi-function fluid flow path channeling the gas supply in a substantially forward direction through a proximal swirl ring inlet to an electrode cooling passage located between an external surface of the electrode and an inner surface of the swirl ring, the multi-function fluid flow path exiting the electrode cooling passage by a distal swirl ring outlet to flow toward the distal end of the torch, such that the plasma cutting system has a power-to-gas flow ratio of at least 2 kilowatts per cubic feet per minute (KW/cfm) of the gas supply that is supplied from the compressor to the plasma arc cutting torch.

2. The plasma cutting system of claim 1 , wherein the compressor is configured to provide the gas supply to the plasma arc torch at a rate of less than about 80 standard cubic feet per hour (scfh).

3. The plasma cutting system of claim 1 , wherein the plasma arc torch is a blowback torch.

4. The plasma cutting system of claim 1 , wherein the circumferential seal is dynamic such that the circumferential seal allows the electrode and the swirl ring to slide relative to each other.

5. The plasma cutting system of claim 1 , further comprising a direct-current-to-direct-current (DC-DC) converter operably connected between an output of the power source and an input of the compressor, wherein the compressor is integrated with the power source.

6. The plasma cutting system of claim 1 , further comprising a thermal regulation system including:
a fan for generating a flow of cooled air;
a heat sink located downstream from the fan, the heat sink connected to a set of electronics in the power source; and
an output tube connected to the compressor and disposed in the power source for conducting the plasma gas from the compressor to the plasma arc torch, the output tube located substantially between the fan and the heat sink such that the output tube is substantially exposed to the flow of cooled air from the fan.

7. The plasma cutting system of claim 6 , further comprising a set of baffles configured to direct the flow of cooled air from the fan to the output tube.

8. The plasma cutting system of claim 6 , wherein the output tube comprises a coil, the diameter of the coil being approximately the same as or less than the annular flow area of the fan such that the coil is substantially immersed in the flow of cooled air.

9. The plasma cutting system of claim 1 , wherein the power source operates at a current of less than about 50 amperes.

10. The plasma cutting system of claim 1 , wherein the plasma cutting system weighs no more than about 30 pounds.

11. The plasma cutting system of claim 1 , wherein the plasma cutting system has a volume of about 1640 inch 3 .

12. The plasma cutting system of claim 1 , wherein the plasma arc torch is configured to substantial inhibit rearward venting of the plasma gas in the plasma arc torch.

13. The plasma cutting system of claim 1 , wherein the power source is configured to deliver a current of greater than about 25 amperes to the plasma arc cutting torch.

14. The plasma cutting system of claim 5 , wherein the power source comprises a boost converter that provides a constant input voltage to the DC-DC converter regardless of the input voltage to the power supply.

15. The plasma cutting system of claim 1 , wherein the multi-function fluid flow path channels the gas supply, after exiting from the electrode cooling passage, through a channel between an external surface of the swirl ring and an internal surface of a retaining cap.

16. The plasma cutting system of claim 15 , wherein the multi-function fluid flow path divides into a first exit channel that directs a first portion of the gas supply to exit the torch via the plasma chamber and a second exit channel that directs a remainder portion of the gas supply to exit the torch via a vent passages extending from an internal surface of the nozzle to an external surface of the nozzle to stabilize the plasma arc and cool the nozzle.

17. The plasma cutting system of claim 6 , wherein at least one of the diameter or the length of the output tube is dimensioned such that the heat transfer rate from the plasma gas within the output tube to an internal surface of the output tube is approximately the same as the heat transfer rate from an exterior surface of the output tube to ambient air.

18. The plasma cutting system of claim 6 , further comprising a water separator connected to the output tube.

19. The plasma cutting system of claim 6 , wherein the fan is configured to cool both the heat sink and the plasma gas in the output tube.

20. The plasma cutting system of claim 1 , wherein the compressor is an internal component of the power supply.

21. The plasma cutting system of claim 1 , wherein the flow rate of the gas supply provided by the compressor to the plasma arc cutting torch is about 65 scfh.

22. The plasma cutting system of claim 16 , wherein the flow rate of the gas supply through the plasma chamber is about 20 scfh.

Assignees

• Hypertherm Inc

Inventors

• Roberts Jesse A
• Patel Shreyansh
• Eickhoff Stephen T
• Gullotta Justin
• Liu Qinghua
• Borowy Dennis M
• Duan Zheng
• Retnaswamy Ashok V
• Kim Sung Je

Classifications

• H05H1/34

  Details, e.g. electrodes, nozzles · CPC title

• H05H2245/125

  Electricity · mapped topic

• B23K10/00 Primary

  Welding or cutting by means of a plasma · CPC title

• H05H2001/3478

  Electricity · mapped topic

• H05H2001/3489

  Electricity · mapped topic