Electrode for plasma arc torch having channels to extend service life
First Claim
1. A method of extending the useful service life of an electrode adapted for supporting an arc in a plasma arc torch, the electrode comprising a tubular holder defining a longitudinal axis and having a discharge end closed by an endwall, the endwall comprising an emissive insert to act as a cathode for transferring the arc to a workpiece, said method comprising the steps of:
- operating the torch so that a plasma arc extends from the emissive insert to a workpiece;
introducing a gas stream around the outside of the electrode with the gas stream moving axially in the direction of the discharge end of the holder; and
directing a portion of the gas stream along a plurality of open channels formed in the holder which terminate adjacent the endwall and radially inwardly across the endwall so as to remove products of erosion and to thereby maintain the endwall substantially free of erosion deposits.
3 Assignments
0 Petitions
Accused Products
Abstract
An electrode and method of operating a plasma arc torch is provided which extends the useful service life of the torch. The electrode includes an elongate tubular holder defining a longitudinal axis and having a discharge end. An endwall closes the discharge end and includes an emissive insert. In one embodiment, the endwall also includes an annular sleeve which separates the insert from physical contact with the holder. Channels formed in the discharge end of the electrode direct a portion of a swirling vortex of gas across the surface of the endwall. The swirling vortex of gas removes products of erosion of the insert and adjacent portion of the sleeve such that the likelihood that arcing will transfer from the insert to the sleeve and/or holder is reduced, and the useful service life of the nozzle-electrode pair is thereby extended.
63 Citations
18 Claims
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1. A method of extending the useful service life of an electrode adapted for supporting an arc in a plasma arc torch, the electrode comprising a tubular holder defining a longitudinal axis and having a discharge end closed by an endwall, the endwall comprising an emissive insert to act as a cathode for transferring the arc to a workpiece, said method comprising the steps of:
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operating the torch so that a plasma arc extends from the emissive insert to a workpiece; introducing a gas stream around the outside of the electrode with the gas stream moving axially in the direction of the discharge end of the holder; and directing a portion of the gas stream along a plurality of open channels formed in the holder which terminate adjacent the endwall and radially inwardly across the endwall so as to remove products of erosion and to thereby maintain the endwall substantially free of erosion deposits. - View Dependent Claims (2)
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3. An electrode adapted for supporting an arc in a plasma arc torch and comprising:
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a tubular holder defining a longitudinal axis and comprising a discharge end; an endwall closing the discharge end of said holder and having an opening formed therein extending axially at least partially therethrough and coaxially with the longitudinal axis defined by said holder; an emissive insert mounted within the opening; and a plurality of open channels formed in the holder which terminate adjacent said endwall, whereby said channels define a corresponding plurality of passageways for directing a portion of a stream of gas along said channels and radially inwardly across said endwall. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A plasma arc torch comprising:
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a torch body; an electrode secured to said torch body, said electrode comprising; an elongate tubular holder defining a longitudinal axis and comprising a discharge end; an endwall closing the discharge end and having an opening formed therein extending axially at least partially therethrough and coaxially with the longitudinal axis defined by said holder; an emissive insert mounted within the opening; and a plurality of open channels formed in the holder which terminate adjacent said endwall; a nozzle secured to the torch body and having a bore therethrough aligned with the longitudinal axis defined by said holder, the bore positioned opposite the discharge end of said holder for constricting a plasma arc; means for generating an electrical arc extending from said emissive insert in the direction of a workpiece; and means for generating a flow of gas between said electrode and said nozzle so as to create a plasma flow through the bore of said nozzle in the direction of the workpiece, whereby a portion of the flow of gas is directed by said channels and said nozzle radially inwardly across said endwall to maintain said endwall substantially free of erosion deposits and to thereby extend the useful service life of the torch. - View Dependent Claims (16, 17, 18)
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Specification