Plasma arc ignition system
First Claim
Patent Images
1. A plasma arc torch contact starting system comprising:
- a torch head having an electrically conductive plasma exit nozzle at one end and a pilot arc chamber within said torch head immediately adjacent the plasma exit nozzle;
an electrode mounted and supported in said torch head for movement relative to the nozzle;
means for biasing the electrode into electrical contact with the nozzle;
means for supplying a flow of pressurized gas to the pilot arc chamber; and
arc-drawing means operably connected to but substantially thermally isolated from the electrode and the torch head for delivering current to the electrode and subsequently displacing the electrode from the nozzle to draw a pilot arc in the pilot arc chamber, wherein the arc-drawing means displaces the electrode in response to pressurized gas diverted from the flow of pressurized gas supplied to the pilot arc chamber, said substantial thermal isolation being effected by placing the arc-drawing means so that it is not within the thermal mass of the torch head that contains the pilot arc chamber and supports the electrode.
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Abstract
In accordance with the present invention, a plasma arc torch contact starting system has a torch head having an electrically conductive plasma exit nozzle at one end and a pilot arc chamber within the torch head immediately adjacent the plasma exit nozzle. An electrode is mounted in the torch head for movement relative to the nozzle. An arc-drawing mechanism is operably connected to but substantially thermally isolated from the electrode and the torch head for biasing the electrode into contact with the nozzle and for displacing the electrode from the nozzle to draw a pilot arc in the pilot arc chamber.
89 Citations
10 Claims
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1. A plasma arc torch contact starting system comprising:
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a torch head having an electrically conductive plasma exit nozzle at one end and a pilot arc chamber within said torch head immediately adjacent the plasma exit nozzle; an electrode mounted and supported in said torch head for movement relative to the nozzle; means for biasing the electrode into electrical contact with the nozzle; means for supplying a flow of pressurized gas to the pilot arc chamber; and arc-drawing means operably connected to but substantially thermally isolated from the electrode and the torch head for delivering current to the electrode and subsequently displacing the electrode from the nozzle to draw a pilot arc in the pilot arc chamber, wherein the arc-drawing means displaces the electrode in response to pressurized gas diverted from the flow of pressurized gas supplied to the pilot arc chamber, said substantial thermal isolation being effected by placing the arc-drawing means so that it is not within the thermal mass of the torch head that contains the pilot arc chamber and supports the electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for contact starting a plasma arc torch having a torch head with a plasma exit nozzle at one end and a pilot arc chamber within said torch head immediately adjacent the plasma exit nozzle, comprising:
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providing an electrode mounted and supported in said torch head for movement relative to the nozzle and biased into electrical contact with the nozzle; providing a gas-actuated cylinder operably connected to but substantially thermally isolated from the electrode and the torch head for displacing the electrode from the nozzle, said substantial thermal isolation being effected by placing the arc-drawing means so that it is not within the thermal mass of the torch head that contains the pilot arc chamber and supports the electrode; providing a primary flow of pressurized gas to the pilot arc chamber; providing a current to the electrode; and diverting a portion of the primary flow of pressurized gas to actuate the gas-actuated cylinder to displace the electrode from the nozzle and draw a pilot arc in the pilot arc chamber.
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Specification