Method for starting and stopping a plasma arc torch
AssigneeVictor Equipment Company
InventorsDaniel Wayne Barnett, Nakhleh A. Hussary
Life of this patent
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Abstract
A method of starting a plasma arc torch is provided that includes directing a pre-flow gas and a start shield gas through the plasma arc torch during generation and transfer of a plasma arc, and switching from the pre-flow gas to a plasma gas, and switching from the start shield gas to a primary shield gas after transfer of the plasma arc to a workpiece. A method of stopping a plasma arc torch is also provided that includes directing a plasma gas and a primary shield gas through the plasma arc torch during steady-state operation, and switching from the primary shield gas to a stop shield gas during ramp down of an operating current.
Claims25
A method of starting a plasma arc torch, comprising:
- directing a pre-flow gas into a plasma chamber formed between an electrode and a tip and directing a start shield gas through a secondary gas passageway of the plasma arc torch during generation and transfer of a plasma arc;
- and
- switching from the pre-flow gas to a plasma gas, and switching from the start shield gas to a primary shield gas after transfer of the plasma arc to a workpiece, wherein the start shield gas has a different composition than the primary shield gas, and mainly that the start shield gas has an ionization energy lower than the primary shield gas.
A method of stopping a plasma arc torch, comprising:
- directing a plasma gas into a plasma chamber formed between an electrode and a tip and directing a primary shield gas through a secondary gas passageway of the plasma arc torch during steady-state operation;
- and
- switching from the primary shield gas to a stop shield gas during ramp down of an operating current, wherein the stop shield gas has a different composition than the primary shield gas, and mainly that the stop shield gas has an ionization energy lower than the primary shield gas.
A method of operating a plasma arc torch, comprising:
- directing a pre-flow gas into a plasma chamber formed between an electrode and a tip and directing a start shield gas through a secondary gas passageway of the plasma arc torch during generation and transfer of a plasma arc;
- switching from the pre-flow gas to a plasma gas, and switching from the start shield gas to a primary shield gas after transfer of the plasma arc to a workpiece, wherein the start shield gas has a composition of gas that is different than the primary shield gas;
- directing a plasma gas into the plasma chamber and directing a primary shield gas through the secondary gas passageway of the plasma arc torch during steady-state operation;
- and
- switching from the primary shield gas to a stop shield gas during ramp down of an operating current, wherein the stop shield gas has a different composition than the primary shield gas, and mainly that the stop shield gas has an ionization energy lower than the primary shield gas.
A method of starting a plasma arc torch comprising transferring a plasma arc to a workpiece without one of a pilot current and a pilot circuit through the use of directing a pre-flow gas into a plasma chamber formed between an electrode and a tip and directing a start shield gas flow through a secondary gas passageway during generation and transfer of the plasma arc, the start shield gas having a different composition than the primary shield gas, and mainly that the start shield gas has a predetermined ionization energy that is different than a primary shield gas used during steady-state operation.
A method of starting a plasma arc torch comprising directing a pre-flow gas into a plasma chamber formed between an electrode and a tip and directing a start shield gas flow through a secondary gas passageway and applying a single pulse of high voltage energy to transfer a plasma arc to a workpiece through the use of the start shield gas flow during generation and transfer of the plasma arc that the start shield gas has a lower ionization energy than a primary shield gas used during steady-state operation and wherein the start shield gas has a different composition than the primary shield gas.
A method of reducing electrode wear in a plasma arc torch comprising directing a primary shield gas through a secondary gas passageway and introducing a flow of a stop shield gas through the secondary gas passageway of the plasma arc torch during a current ramp down period, the stop shield gas having a lower ionization energy and a different composition than the primary shield gas used during steady-state operation, wherein the stop shield gas enables the current to be ramped down to a lower level before a plasma arc is extinguished such that molten emissive element material developed in the electrode during steady-state operation is cooled and solidified to reduce ejection of the molten emissive element material from the electrode.
Dependencies are inferred from the claim text.