Abstract: A shield device for a plasma arc torch includes an inner shield member defining an inner auxiliary gas chamber and an outer shield member surrounding the inner shield member. An outer auxiliary gas chamber is defined between the inner shield member and outer shield member. The shield device allows an auxiliary gas flow to be split into a first flow of auxiliary gas through the inner auxiliary gas chamber and a second flow of auxiliary gas through the outer auxiliary gas chamber. The inner shield member and the outer shield member are configured to be mounted to the plasma arc torch as an integral unit.

Abstract: A method of manufacturing an electrode for use in a plasma arc torch is provided that includes forming a conductive body to define a proximal end portion, a distal end portion, a distal end face disposed at the distal end portion, a central cavity, and a central protrusion disposed within the central cavity near the distal end portion. A plurality of emissive inserts are inserted through the distal end face and into the central protrusion. The plurality of emissive inserts are pressed into the central protrusion and both a proximal end portion of the central protrusion and the plurality of emissive inserts are deformed such that the plurality of emissive inserts extend radially and outwardly from the distal end portion at an angle relative to the distal end portion.

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.

Abstract: A component for use in a plasma arc torch is provided that includes an orifice that defines a continuously changing cross-sectional size along the length of a surface of the orifice from an inlet portion to an outlet portion. The surface extends along the component and directs a flow of shield gas at a predetermined angle to result in a specific pierce or cut location on a workpiece. In one form, the component is a shield cap. The continuously changing surface may be convergent, divergent, or a combination of convergent and divergent according to the principles of the present disclosure. Additionally, the shield cap may comprise a single, unitary piece or alternately a plurality of pieces or components.

Abstract: A method of starting a multi-gas plasma arc torch for cutting a workpiece is provided that includes directing a pre-flow gas within the plasma arc torch and switching the pre-flow gas to a plasma gas before a pilot arc is transferred to the workpiece. The plasma gas is supplied initially at a first gas pressure when the pre-flow gas is switched to the plasma gas. The gas pressure is switched to a second gas pressure that is different than the first gas pressure after the pilot arc is transferred. The method provides a smooth transition from the pre-flow gas to the plasma gas and reduces the time delay in replacing the pre-flow gas with the plasma gas in the plasma arc torch, thereby improving cut or marking quality.

Abstract: An electrode for a plasma arc torch is provided by the teachings of the present disclosure. In one form, the electrode includes a conductive body, a plurality of deformed emissive inserts, and a dimple. In one form, the plurality of emissive inserts are concentrically nested about the centerline of the conductive body, and the dimple is positioned concentrically about a centerline of the conductive body. The plurality of emissive inserts and the dimple increase the life of the electrode.

Abstract: A plasma arc torch is provided that includes a tip having an improved life. The tip defines a first set of fluid passageways, a second set of fluid passageways and an internal cavity in fluid communication with the first and second fluid passageways. The internal cavity includes a base portion disposed proximate and surrounding a central orifice of the tip. A first set of fluid passageways allow for entry of a cooling fluid into the tip and a second set of fluid passageways allow for exit of the cooling fluid from the tip.

Abstract: A method of manufacturing an electrode for use in a plasma arc torch is provided that includes forming a conductive body to define a proximal end portion, a distal end portion, a distal end face disposed at the distal end portion, a central cavity, and a central protrusion disposed within the central cavity near the distal end portion. A plurality of emissive inserts are inserted through the distal end face and into the central protrusion. The plurality of emissive inserts are pressed into the central protrusion and both a proximal end portion of the central protrusion and the plurality of emissive inserts are deformed such that the plurality of emissive inserts extend radially and outwardly from the distal end portion at an angle relative to the distal end portion.

Abstract: A drag tip for use in a plasma cutting torch is provided that includes an inner tip portion defining a distal end face, an inner cavity through which a plasma gas flows, and an orifice disposed between the distal end face and the inner cavity. An outer tip portion surrounds the inner tip portion and defines an inner chamber to accommodate a flow of secondary gas and also a distal end portion. The distal end face of the inner tip portion is adapted for contact with a workpiece and extends distally beyond the distal end portion of the outer tip portion, and the flow of secondary gas exits the outer tip portion proximate the distal end portion. Variations of the drag tip and methods of operation are also provided.

Abstract: In general, the present invention provides a method of piercing a workpiece with a plasma arc torch of the type having a plasma gas flow path for directing a plasma gas through the torch and a secondary gas flow path for directing a secondary gas through the torch. The method comprises directing a flow of shield gas along a distal end portion of the plasma arc torch to deflect metal spatter generated from the piercing, and ramping a current provided to the plasma arc torch along a profile during piercing and controlling current ramp parameters as a function of a thickness of the workpiece and an operating current level, wherein the current ramp parameters comprise a length of time, a ramp rate, a shape factor, and a modulation.

Abstract: A shield device for a plasma arc torch includes an inner shield member defining an inner auxiliary gas chamber and an outer shield member surrounding the inner shield member. An outer auxiliary gas chamber is defined between the inner shield member and outer shield member. The shield device allows an auxiliary gas flow to be split into a first flow of auxiliary gas through the inner auxiliary gas chamber and a second flow of auxiliary gas through the outer auxiliary gas chamber. The inner shield member and the outer shield member are configured to be mounted to the plasma arc torch as an integral unit.

Abstract: Methods and devices for controlling the flow of gases through a plasma arc torch are provided. A flow of plasma gas is directed to a plasma chamber, a first flow of auxiliary gas is directed around a plasma stream that exits a tip in one of a swirling manner and a radial manner, and a second flow of auxiliary gas is directed around the first flow of auxiliary gas and the plasma stream in one of a coaxial manner, an angled manner, and a radial manner. The first flow of auxiliary gas functions to constrict and shape the plasma stream to improve cut quality and cut speed, and the second flow of auxiliary gas functions to protect the plasma arc torch during piercing and cutting and to cool components of the plasma arc torch such that thicker workpieces may be processed with a highly shaped plasma stream.

Abstract: A component for use in a plasma arc torch is provided that includes an orifice that defines a continuously changing cross-sectional size along the length of a surface of the orifice from an inlet portion to an outlet portion. The surface extends along the component and directs a flow of shield gas at a predetermined angle to result in a specific pierce or cut location on a workpiece. In one form, the component is a shield cap. The continuously changing surface may be convergent, divergent, or a combination of convergent and divergent according to the principles of the present disclosure. Additionally, the shield cap may comprise a single, unitary piece or alternately a plurality of pieces or components.

Abstract: A component for use in a plasma arc torch is provided that includes a continuously contoured surface extending along the component that directs a flow of shield gas at a predetermined angle to result in a specific pierce or cut location on a workpiece. In one form, the component is a shield cap that includes an exit orifice extending through a central portion of the shield cap, the exit orifice defining an inlet portion and an outlet portion, and a continuously contoured surface extending between the inlet portion and the outlet portion. The continuously contoured surfaces may be convergent, divergent, or a combination of convergent and divergent according to the principles of the present disclosure. Additionally, the shield cap may comprise a single, unitary piece or alternately a plurality of pieces or components.

Abstract: In general, the present invention provides a method of piercing a workpiece with a plasma arc torch of the type having a plasma gas flow path for directing a plasma gas through the torch and a secondary gas flow path for directing a secondary gas through the torch. The method comprises directing a flow of shield gas along a distal end portion of the plasma arc torch to deflect metal spatter generated from the piercing, and ramping a current provided to the plasma arc torch along a profile during piercing and controlling current ramp parameters as a function of a thickness of the workpiece and an operating current level, wherein the current ramp parameters comprise a length of time, a ramp rate, a shape factor, and a modulation.

Abstract: A drag tip for use in a plasma cutting torch is provided that includes an inner tip portion defining a distal end face, an inner cavity through which a plasma gas flows, and an orifice disposed between the distal end face and the inner cavity. An outer tip portion surrounds the inner tip portion and defines an inner chamber to accommodate a flow of secondary gas and also a distal end portion. The distal end face of the inner tip portion is adapted for contact with a workpiece and extends distally beyond the distal end portion of the outer tip portion, and the flow of secondary gas exits the outer tip portion proximate the distal end portion. Variations of the drag tip and methods of operation are also provided.

Abstract: Methods and devices for controlling the flow of gases through a plasma arc torch are provided. A flow of plasma gas is directed to a plasma chamber, a first flow of auxiliary gas is directed around a plasma stream that exits a tip in one of a swirling manner and a radial manner, and a second flow of auxiliary gas is directed around the first flow of auxiliary gas and the plasma stream in one of a coaxial manner, an angled manner, and a radial manner. The first flow of auxiliary gas functions to constrict and shape the plasma stream to improve cut quality and cut speed, and the second flow of auxiliary gas functions to protect the plasma arc torch during piercing and cutting and to cool components of the plasma arc torch such that thicker workpieces may be processed with a highly shaped plasma stream.

Abstract: A component for use in a plasma arc torch is provided that includes a continuously contoured surface extending along the component that directs a flow of shield gas at a predetermined angle to result in a specific pierce or cut location on a workpiece. In one form, the component is a shield cap that includes an exit orifice extending through a central portion of the shield cap, the exit orifice defining an inlet portion and an outlet portion, and a continuously contoured surface extending between the inlet portion and the outlet portion. The continuously contoured surfaces may be convergent, divergent, or a combination of convergent and divergent according to the principles of the present disclosure. Additionally, the shield cap may comprise a single, unitary piece or alternately a plurality of pieces or components.

Abstract: Methods of forming an electrode for use in a plasma arc torch are provided that generally include forming an electrode body defining a proximal end portion and a distal end portion, forming a recess within the distal end portion, securing a slug within the recess of the distal end portion, creating a bore through the slug and the distal end portion of the electrode body, and securing an emissive insert within the bore. In another form, a hybrid electrode is provided, which is formed by the manufacturing methods of the present invention, and which includes an electrode body defining a cavity, a secondary body secured to the electrode body, and an emissive element secured within the bore and in contact with the secondary body and the electrode body, wherein the secondary body is not exposed to the cavity.

Abstract: A gas distributor for use in a plasma arc torch is provided that has at least one plasma gas passageway formed conjointly with a metering passageway, and at least one helical gas passageway formed along an interior portion of the gas distributor, wherein the helical gas passageway is in fluid communication with the plasma gas passageway and the metering passageway. The combination of the metering passageway and the helical gas passageway provides for a metered flow rate and a controlled swirling flow of plasma gas within the plasma arc chamber, respectively, which functions to reduce the amount of molten emissive insert that is ejected from within an electrode at arc shut off, thereby resulting in an increased life of the consumable electrode.