Electrode for plasma arc torch and method of making same
First Claim
Patent Images
1. An electrode for supporting an electric arc in a plasma arc torch, and comprising:
- a metallic holder having a front face and a receptacle formed in the front face;
a relatively non-emissive separator mounted in the receptacle and constructed of silver alloyed with 0.5 to 4 percent of an additional material selected from the group consisting of copper, aluminum, iron, lead, zinc, and alloys thereof, the separator defining an opening therein; and
an emissive element composed of a metallic material having a relatively low work function, the emissive element extending at least partially in the opening of the separator such that the separator is interposed between and separates the metallic holder from the emissive element at the front face of the holder, whereby the separator acts to resist detachment of the electric arc from the emissive element and attachment of the arc to the metallic holder.
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Abstract
An electrode for a plasma arc torch comprises a copper holder having a lower end which mounts an emissive element serving as the cathode terminal for the arc during operation. A relatively non-emissive separator formed of silver alloyed with 0.5 to 4 percent of copper or other metals surrounds the emissive element and separates the emissive element from the copper holder at the exposed end face of the electrode. The separator serves to prevent the arc from detaching from the emissive element and attaching to the copper holder.
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Citations
12 Claims
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1. An electrode for supporting an electric arc in a plasma arc torch, and comprising:
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a metallic holder having a front face and a receptacle formed in the front face; a relatively non-emissive separator mounted in the receptacle and constructed of silver alloyed with 0.5 to 4 percent of an additional material selected from the group consisting of copper, aluminum, iron, lead, zinc, and alloys thereof, the separator defining an opening therein; and an emissive element composed of a metallic material having a relatively low work function, the emissive element extending at least partially in the opening of the separator such that the separator is interposed between and separates the metallic holder from the emissive element at the front face of the holder, whereby the separator acts to resist detachment of the electric arc from the emissive element and attachment of the arc to the metallic holder. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10, 11)
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8. A plasma arc torch, comprising:
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an electrode which includes; a metallic holder having a front face and a receptacle formed in the front face, the holder defining a longitudinal axis; a relatively non-emissive separator mounted in the receptacle and constructed of silver alloyed with 0.5 to 4 percent of an additional material selected from the group consisting of copper, aluminum, iron, lead, zinc, and alloys thereof, the separator defining an opening therein; and an emissive element composed of a metallic material having a relatively low work function, the emissive element extending at least partially in the opening of the separator such that the separator is interposed between and separates the metallic holder from the emissive element at the front face of the holder; a nozzle mounted adjacent the front face of the holder and having a flow path therethrough which is aligned with the longitudinal axis; an electrical supply for creating an arc extending from the emissive element of the electrode through the nozzle flow path and to a workpiece located adjacent the nozzle; and a gas supply for creating a flow of a gas between the electrode and the nozzle and so as to create a plasma flow outwardly through the nozzle flow path and to the workpiece. - View Dependent Claims (9, 12)
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Specification