Plasma arc torch with vented flow nozzle retainer

• US 6,084,199 A
• Filed: 08/01/1997
• Issued: 07/04/2000
• Est. Priority Date: 08/01/1997
• Status: Expired due to Term

• Current Assignee: Hypertherm Incorporated
• Original Assignee: Hypertherm Incorporated
• Inventors: Lindsay, Jon, Vandiver, Michael W., Eickhoff, Stephen T.
• Primary Examiner(s): PASCHALL, MARK H
• Application Number:
  US08/905,001
• Time in Patent Office: 1,068 Days
• Field of Search: 219/121.49, 219/121.5, 219/121.52, 219/121.51, 219/74, 219/75, 219/121.39, 219/121.44, 219/121.59, 313/231.31, 313/231.41
• US Class Current: 219/121.52
• 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 1/3457 Nozzle protection devices
• CPC Class Codes: H05H 1/3468 Vortex generators
• CPC Class Codes: H05H 1/3489 Means for contact starting

Abstract

A flow of ionizable gas is provided to a shielded plasma arc torch which includes an electrode, a translatable nozzle, a nozzle retainer, and a shield. After passing through a heat exchanger to cool the electrode, the gas flow enters an annular chamber where the flow is divided into three subflows. A first subflow enters a plasma chamber formed by the electrode, the nozzle, and a swirl ring to pressurize the plasma chamber and support a plasma arc. The second subflow passes serially through apertures in the nozzle retainer and the shield to shield the plasma arc. The remaining flow is vented to ambient. Accordingly, a single gas flow may be employed to independently support multiple torch operating requirements.

Claims

1. A method of operating a shielded plasma arc torch comprising the steps of:

providing a flow of an ionizable gas to a torch body;

passing the flow through a heat exchanger in thermal communication with an electrode disposed in the torch body;

dividing the flow thereafter into;

a first subflow for passage through a plasma chamber formed between the electrode and a nozzle to sustain a plasma arc;

a second subflow for passage through a shield to shield the plasma arc; and

a remaining flow; and

venting the remaining flow to ambient remote from the plasma arc through at least one aperture formed in a nozzle retainer side wall.

2. The invention according to claim 1 wherein the first subflow passes through at least one aperture formed by a swirl ring bounding the plasma chamber, at least in part.

3. The invention according to claim 1 wherein the first subflow is throttled by an orifice formed in the nozzle.

4. The invention according to claim 1 wherein the second subflow passes through and is throttled by at least one aperture formed in a nozzle retainer flange.

5. A method of operating a shielded plasma arc torch comprising the steps of:

providing a first flow of a gas to a torch body;

passing the first flow through a heat exchanger in thermal communication with an electrode disposed in the torch body;

dividing the flow thereafter into;

a first subflow for passage through a shield to shield a plasma arc; and

a remaining flow; and

venting the remaining flow to ambient remote from the plasma arc through at least one aperture formed in a nozzle retainer side wall.

6. The invention according to claim 5 further comprising the step of providing a second flow of an ionizable gas to pressurize a plasma chamber formed between the electrode and a nozzle to sustain a plasma arc.

7. A plasma arc torch nozzle retainer comprising:

a retaining cap comprising;

a generally cylindrical wall having a first end and a second end defining a longitudinal cap axis; and

a radially inwardly directed flange extending from the wall, the flange forming;

a first aperture generally centered along the cap axis for permitting passage therethrough of a nozzle; and

a second aperture radially offset from the first aperture for passage therethrough of a shield gas flow;

wherein the wall forms a third aperture spaced from the second aperture for passage therethrough of a vent gas flow to ambient remote from a plasma arc.

8. The invention according to claim 7 wherein the second aperture defines an aperture axis which is oriented substantially skew relative to the cap axis.

9. The invention according to claim 7 wherein the flange further forms a plurality of second apertures radially offset from the first aperture.

10. The invention according to claim 9 wherein the plurality of second apertures are formed at a substantially constant radial dimension from the cap axis.

11. The invention according to claim 9 wherein the plurality of second apertures are formed at substantially equi-spaced circumferential locations.

12. The invention according to claim 7 wherein the flange comprises a first longitudinally facing surface for limiting travel of a translatable nozzle passing through the first aperture.

13. The invention according to claim 12 wherein the flange further comprises a second longitudinally facing surface for reacting a spring element.

14. The invention according to claim 7 wherein the third aperture defines an aperture axis which is oriented to intersect the cap axis.

15. The invention according to claim 14 wherein the wall further forms a plurality of third apertures.

16. The invention according to claim 15 wherein the plurality of third apertures are formed at a substantially constant longitudinal location.

17. The invention according to claim 15 wherein the plurality of third apertures are formed at substantially equi-spaced circumferential locations.

18. The invention according to claim 7 further comprising a generally cylindrical bearing member mounted to the retaining cap, the bearing member comprising a radially inwardly directed flange forming a first aperture for radially locating a nozzle movably disposed therethrough.

19. The invention according to claim 18 wherein the bearing member further comprises an electrically insulative material.

20. The invention according to claim 7 further comprising a generally cylindrical sleeve circumscribing at least a portion of the cap wall, the sleeve comprising an electrically insulative material.