Abstract: A threaded connection for an electrode holder and an electrode in a plasma arc torch is provided. The threaded connection has relatively low height, and the engaged portion of a male threaded portion of the electrode and a female threaded portion of the electrode holder are positioned at least partially within a nozzle chamber. In one inventive aspect, the nominal pitch diameter of the electrode is less than the minor diameter of the electrode. In another, the width of the root area of the electrode thread is wider than the width of the root area of the electrode holder thread by at least about 35%. The width of the root area of the electrode is at least about 15% wider than the width of the crest portion of the electrode. As such, the less consumable of the two parts, the electrode holder, is provided with a thread that is less likely to be worn and damaged. In one particular embodiment, the crest profile of the electrode is that of a Stub Acme thread separated by a larger root profile.

Abstract: A plasma arc torch both cutting and marking of metal workpieces includes a plasma nozzle having a plasma nozzle orifice through which an electric arc from an electrode and a stream of plasma gas are emitted toward a workpiece, and a liquid-injection shield cup that injects liquid tangentially inwardly to the arc and stream of plasma gas. A power supply is operable to selectively deliver electrical power to the electrode at either a low power level suitable for marking of a workpiece or a high power level suitable for workpiece cutting. The torch may be selectively operated to mark at the low power level, with a plasma marking gas being delivered to the plasma gas passage, or to cut at the high power level, with a plasma cutting gas being delivered to the plasma gas passage, and liquid being delivered to the liquid injection passage for both cutting and marking.

Abstract: A special-purpose plasma arc torch for gouging grooves in a metal workpiece includes an angled nozzle having a bore made up of a first bore portion and a second bore portion that makes an angle of about 15° to about 75° with the first bore portion. The nozzle includes a proximal portion and a distal portion, the proximal portion being adapted for surrounding an electrode assembly when the nozzle is installed in the torch, the distal portion being adapted such that a part of the distal portion extends beyond a front face of an electrode of the torch. The part of the distal portion extending beyond the front face of the electrode has an exterior shape other than cylindrical or conical, and preferably has a non-axisymmetric shape that makes it suitable for fitting within a deep groove in a workpiece.

Abstract: A plasma arc torch includes an annular baffle defining distinct faces A, B, C, and D. Faces A and C are opposite from each other, and faces B and D are opposite from each other. First passages for fluid flow extend between the faces A and C, and second passages extend between the faces B and D. The baffle is installable in an annular space between an inner wall and an outer wall, in either of two orientations. In a first orientation, the first passages are open to fluid flow and the second passages are closed by engagement of the inner and outer walls with the faces B and D, and in a second orientation, flipped over relative to the first orientation, the second passages are open to fluid flow and the first passages are closed by engagement of the inner and outer walls with the faces A and C.

Abstract: A system for supplying fluids to a plasma arc torch includes a single-gas power supply for regulating electrical power to the torch and for regulating supply of a first fluid to the torch, a flow regulator for regulating supply of a second fluid to the torch, and a first pressure-actuated valve disposed between the flow regulator and the torch. The valve shuts off supply of the second fluid to the torch when the first valve is closed and allows the second fluid to be supplied when the first valve is open. The first valve is opened by pressure of the first fluid supplied to the torch and closed when the first fluid is not supplied to the torch. A second pressure-actuated valve may be provided in the supply line for the first fluid, which is opened by pressure of the second fluid being supplied to the torch.

Abstract: An improved plasma torch and method of starting the torch are provided. The torch may comprise a main torch body with an electrode assembly coupled to a piston therein. The piston and electrode assembly are moveable between a starting position whereby the electrode assembly contacts a nozzle, and an operating position whereby the electrode assembly does not contact the nozzle. The piston is moveable by directing fluid, which may comprise coolant, through the plasma torch either in a first direction which biases the piston to the starting position, or in an opposite second direction which biases the piston so as to retract the electrode assembly to the operating position. A reversing valve or reversible pump may be used to control the direction of the flow of the fluid. Thereby, the coolant supply may be used to both cool the torch and control the starting and operation of the torch.

Abstract: A plasma arc torch is provided that includes a wear stop designed to detect wear of an electrode and prevent the use of the electrode once the electrode has experienced a certain amount of wear. Either the electrode or the nozzle is movable with respect to the main torch body, and the movable component defines a projection. The wear stop is positioned a predetermined distance from a nozzle of the torch, such that prior to experiencing an excessive amount of wear, the electrode is able to contact the nozzle and initiate a pilot arc for starting a torch operation. Once the length of the electrode becomes shorter than a predetermined length due to wear, the projection of the electrode engages the wear stop, and the wear stop prevents the electrode from contacting the nozzle. In this way, an electrode that is excessively worn cannot be used in subsequent torch operations.

Abstract: A system for supplying fluids to a plasma arc torch includes a single-gas power supply for regulating supply of electrical power to the plasma arc torch and for regulating supply of a first fluid to the plasma arc torch, a flow regulator for regulating supply of a second fluid to the plasma arc torch, and a first pressure-actuated valve disposed between the flow regulator and the plasma arc torch. The pressure-actuated valve shuts off supply of the second fluid to the torch when the first pressure-actuated valve is closed and allows the second fluid to be supplied to the torch when the first pressure-actuated valve is open. The first pressure-actuated valve is structured and arranged to be opened by pressure of the first fluid being supplied to the torch and to be closed when the first fluid is not being supplied to the torch. The system can also include a second pressure-actuated valve in the supply line for the first fluid, which is opened by pressure of the second fluid being supplied to the torch.

Abstract: An improved plasma torch and method of starting the torch are provided. The torch may comprise a main torch body with an electrode assembly coupled to a piston therein. The piston and electrode assembly are moveable between a starting position whereby the electrode assembly contacts a nozzle, and an operating position whereby the electrode assembly does not contact the nozzle. The piston is moveable by directing fluid, which may comprise coolant, through the plasma torch either in a first direction which biases the piston to the starting position, or in an opposite second direction which biases the piston so as to retract the electrode assembly to the operating position. A reversing valve or reversible pump may be used to control the direction of the flow of the fluid. Thereby, the coolant supply may be used to both cool the torch and control the starting and operation of the torch.

Abstract: A plasma arc torch is provided that includes a wear stop designed to detect wear of an electrode and prevent the use of the electrode once the electrode has experienced a certain amount of wear. Either the electrode or the nozzle is movable with respect to the main torch body, and the movable component defines a projection. The wear stop is positioned a predetermined distance from a nozzle of the torch, such that prior to experiencing an excessive amount of wear, the electrode is able to contact the nozzle and initiate a pilot arc for starting a torch operation. Once the length of the electrode becomes shorter than a predetermined length due to wear, the projection of the electrode engages the wear stop, and the wear stop prevents the electrode from contacting the nozzle. In this way, an electrode that is excessively worn cannot be used in subsequent torch operations.

Abstract: An improved plasma torch and method of starting the torch are provided. The torch may comprise a main torch body with an electrode assembly coupled to a piston therein. The piston and electrode assembly are moveable between a starting position whereby the electrode assembly contacts a nozzle, and an operating position whereby the electrode assembly does not contact the nozzle. The piston is moveable by directing fluid, which may comprise coolant, through the plasma torch either in a first direction which biases the piston to the starting position, or in an opposite second direction which biases the piston so as to retract the electrode assembly to the operating position. A reversing valve or reversible pump may be used to control the direction of the flow of the fluid. Thereby, the coolant supply may be used to both cool the torch and control the starting and operation of the torch.

Abstract: A metering system and associated method for supplying gas to a torch are provided. The metering system includes a controller that is configured to adjust a pressure regulator according to the pressure and flow rate of the gas delivered to the torch. For example, the torch can be a plasma arc torch that has an electrode positioned in a nozzle and operates in a working mode by providing an arc from the electrode to a workpiece. In a first mode of operation, the metering system can provide a gas to the torch by adjusting the pressure regulator according to the pressure downstream of the pressure regulator. In a second mode of operation, the metering system can provide adjust the pressure regulator according to the flow rate of the gas through a flow transducer in series with the pressure regulator.

Abstract: A plasma arc generation system includes a power module operably engaged with a plasma arc torch head portion and adapted to provide an electrical current for causing an arc at the torch head portion or generating a plasma. A cooling device is operably engaged with the power module so as to direct a fluid thereto for cooling the power module. The cooling device is configured such that the fluid directly contacts the power module to receive heat therefrom generated by the power module. Associated systems and methods are also provided.

Abstract: A plasma torch is provided having a movable member carrying an electrode and movable along a tubular member bore having a nozzle at one end. A piston member engaged with the movable member moves the electrode between inoperable and operable positions within the bore, the movable member being biased outwardly of the one end of the bore. A first sealing member engaged with the piston member allows a fluid flow into the bore to act on the piston member to move the electrode to the operable position when the nozzle/electrode is engaged with the tubular member. A second sealing member, engaged with the bore, engages the piston member when the nozzle/electrode is removed. The fluid flow enters the bore between the sealing members, the second sealing member thus preventing torch operation when the nozzle/electrode is removed by preventing the fluid flow from acting on the piston.

Abstract: A slag-removal system for a cutting table includes a pair of drive members arranged in spaced endless loops extending parallel to a longitudinal direction, with a slag plow connected between the drive members, each loop having a lower run and an upper run spaced above the lower run. The slag plow is carried along the lower runs as the drive members are rotated, such that the plow scrapes slag from the support surface beneath the table. As the drive members continue to rotate in the same direction, the plow is carried along the upper runs of the drive members back to its starting location for another slag-removal cycle.

Abstract: A threaded connection for an electrode holder and an electrode in a plasma arc torch is provided. The threaded connection has relatively low height, and the engaged portion of a male threaded portion of the electrode and a female threaded portion of the electrode holder are positioned at least partially within a nozzle chamber. In one inventive aspect, the nominal pitch diameter of the electrode is less than the minor diameter of the electrode. In another, the width of the root area of the electrode thread is wider than the width of the root area of the electrode holder thread by at least about 35%. The width of the root area of the electrode is at least about 15% wider than the width of the crest portion of the electrode. As such, the less consumable of the two parts, the electrode holder, is provided with a thread that is less likely to be worn and damaged. In one particular embodiment, the crest profile of the electrode is that of a Stub Acme thread separated by a larger root profile.

Abstract: Disclosed is a system for interdependent control of multiple power sources. The system includes at least first and second power sources for supplying power to an electrical load. At least first and second sensors are respectively coupled with outputs of the first and second power sources, such that the first and second sensors respectively emit first and second signals indicative of the output of the first and second power sources. A comparator unit is coupled to the first and second sensors for comparing the first and second signals emitted by the first and second sensors. The comparator unit is configured for emitting a difference signal indicating a difference between the first and second signals. A controller unit coupled to the comparator unit and at least one of said first and second power sources is configured for controlling at least one of said first and second power sources based on the difference signal.

Abstract: A plasma arc torch and methods for assembling and disassembling a plasma arc torch wherein a plurality of front end parts of the torch form a unit that is removable from the torch in a single operation to gain access to the electrode. The unit can then be reinstalled in the torch in a single operation after replacement of the electrode. An assembly fixture is employed to facilitate pre-assembly of the unit of front end parts prior to installation of the unit in a torch.

Abstract: A fastening arrangement comprising a thread-forming lobular screw and a member defining a non-tapped pilot hole therein. The screw has a shaft and a head joined to a proximal end of the shaft, the shaft defining a plurality N of lobes circumferentially spaced about a central longitudinal axis of the shaft, a thread being formed on an outer surface of the shaft. The pilot hole comprises a central portion of a diameter intermediate the minor and major diameters of the screw thread, and a plurality N of circumferentially spaced cutouts extending radially out from the central portion. A plurality of longitudinally extending edges parallel to the axis of the screw are defined at junctures between the cutouts and central portion of the pilot hole. The screw thread forms a thread in the member beginning at the longitudinal edges of the pilot hole.

Abstract: A metering system and associated method for supplying gas to a torch are provided. The metering system includes a controller that is configured to adjust a pressure regulator according to the pressure and flow rate of the gas delivered to the torch. For example, the torch can be a plasma arc torch that has an electrode positioned in a nozzle and operates in a working mode by providing an arc from the electrode to a workpiece. In a first mode of operation, the metering system can provide a gas to the torch by adjusting the pressure regulator according to the pressure downstream of the pressure regulator. In a second mode of operation, the metering system can provide adjust the pressure regulator according to the flow rate of the gas through a flow transducer in series with the pressure regulator.