Dielectric devices for a plasma arc torch
First Claim
1. A dielectric shield for use in a plasma arc torch, the plasma arc torch including a nozzle and an electrode, the plasma arc torch in operation generating a plasma arc that passes from the electrode through the nozzle to process a workpiece, the dielectric shield comprising:
- a metallic body having a side wall, an end face extending generally transversely to a plasma that exits through an orifice in the end face and processes the workpiece;
a dielectric coating disposed on the exterior surfaces of the metallic body, the dielectric coating to thereby prevent a current path from forming between the workpiece and the metallic body during a processing of the workpiece.
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Accused Products
Abstract
Apparatus and methods for thermally processing a workpiece include directing a plasma arc to the workpiece and using a dielectric shield or dielectric coating to protect a forward portion (e.g., a torch head) of a plasma arc torch. The dielectric shield or dielectric coating covers a nozzle disposed within the torch head and protects the nozzle from the effects of slag and double arcing. The shield also improves operator visibility due to the spatial relationship between the dielectric shield and the nozzle.
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Citations
31 Claims
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1. A dielectric shield for use in a plasma arc torch, the plasma arc torch including a nozzle and an electrode, the plasma arc torch in operation generating a plasma arc that passes from the electrode through the nozzle to process a workpiece, the dielectric shield comprising:
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a metallic body having a side wall, an end face extending generally transversely to a plasma that exits through an orifice in the end face and processes the workpiece; a dielectric coating disposed on the exterior surfaces of the metallic body, the dielectric coating to thereby prevent a current path from forming between the workpiece and the metallic body during a processing of the workpiece. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A torch head for use in a plasma arc torch, the plasma arc torch including a nozzle and an electrode, the plasma arc torch in operation generating a plasma arc that passes from the electrode through the nozzle to process a workpiece, the torch head comprising:
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a nozzle mounted relative to an electrode in a torch body to define a plasma chamber in which a plasma arc is formed, the nozzle comprising a conductive nozzle body portion and defining a nozzle exit orifice extending therethrough; and a dielectric shield capable of being secured to the torch body such that at least a portion of a surface of the shield directly contacts the nozzle body portion, the dielectric shield at least partially defining a cooling passage for providing a cooling gas to the torch head and comprising a metallic body being dimensioned to inhibit the nozzle from protruding past the end face of the metal body when the metallic body is attached to the plasma arc torch; a dielectric coating disposed on the metallic body, the dielectric coating sufficient to prevent a current path from forming between the workpiece and the metallic body during processing of the workpiece. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method of protecting a plasma arc torch including an electrode and a nozzle disposed within a torch body, the method comprising:
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securing a shield having a metallic body, a side wall, an end face extending generally transversely to a plasma that exits through an orifice in the end face and processes the work piece; and preventing a current path from forming between the workpiece and the metal body during processing of the workpiece by dielectrically coating the metal body. - View Dependent Claims (28, 29, 30, 31)
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Specification