Abstract: In a power source for an electric arc welder including an inverter having two primary circuits connected in a series circuit across the DC bus of an input rectifier where each primary circuit comprises a capacitor parallel with a primary winding section and a switch to apply the voltage of the capacitor across the primary winding section, so that the primary circuits alternately create a voltage pulse in the primary winding sections to induce voltage pulses in a secondary circuit having a secondary winding coupled to said primary windings and connected by an output circuit to an output welding circuit. There is provided one improvement. The improvement is a soft ferrite saturable reactor in at least one of the series circuit or the output circuit to delay the voltage pulse in the primary winding sections.

Abstract: An open shipyard feeder for supplying a consumable welding wire on a wire spool to a welding gun. The feeder includes a frame having a base extending in a longitudinal direction between a forward end and a rearward end and which supports the feeder on an underlying surface. The frame further includes a spool support means connected to the frame near the rearward end and which rotatably retains the wire spool relative to the frame allowing the spool to rotate about a spool axis. The feeder includes a wire advancing mechanism mounted on the frame for paying wire from the spool on the spool support to the welding gun. The feeder further includes a control box on the frame near the forward end. The feeder frame is rigid yet light weight and can support the wire feeder on a wide range of underlying surfaces while still being easily transportable.

Abstract: An open shipyard feeder for supplying a consumable welding wire on a wire spool to a welding gun. The feeder includes a frame having a base extending in a longitudinal direction between a forward end and a rearward end and which supports the feeder on an underlying surface. The frame further includes a spool support means connected to the frame near the rearward end and which rotatably retains the wire spool relative to the frame allowing the spool to rotate about a spool axis. The feeder includes a wire advancing mechanism mounted on the frame for paying wire from the spool on the spool support to the welding gun. The feeder further includes a control box on the frame near the forward end. The feeder frame is rigid yet light weight and can support the wire feeder on a wide range of underlying surfaces while still being easily transportable.

Abstract: In an electric arc welder including a main transformer with a primary stage coupled to a secondary stage in which is created an AC output current, a first switch opened and closed at a given rate to pass a series of first pulses of DC current in a first circuit having a first lead and through at least a portion of the primary stage in a first electrical direction, with each of the first pulses having a length determined by the time the first switch is closed, a second switch opened and closed at the given rate to pass a series of second pulses of DC current in a second circuit having a second lead through at a least a portion of the primary stage in a second electrical direction with each of the second pulses having a length determined by the time the second switch is closed, and a control circuit for rapidly closing the first and second switches in sequence to induce an AC current in the output stage, the improvement comprising: a first current transformer surrounding the first lead of the first circuit to d

Abstract: In a switching type power supply for use in an electric arc welder or plasma cutter, of the type having an output transformer with a primary winding in a series circuit DC source with a selected voltage and a switch, either single or tandem, with a conductive on state to pass a current pulse through the primary winding in a first electrical direction and a non-conductive off state disconnecting the DC voltage source from the winding and a large filter capacitor across the DC input voltage source, the improvement comprising: a snubber network for transferring energy due to the leakage inductance of the primary winding to the filter capacitor when the switch is shifted from the on state to the off state where the snubber network includes a storage capacitor with a diode controlled resonant charging circuit so the winding is in a tank circuit with the storage capacitor to charge the storage capacitor in a charging cycle when the switch shifts from the on state to the off state and a diode controlled discharging

Abstract: A plasma torch comprises a tubular nozzle having an end wall and an electrode in the nozzle having a nose end facing the end wall. The nose end and end wall provide a plasma gas chamber, and the end wall has a gas chamber outlet opening extending axially therethrough. The gas chamber has an entrance radially outwardly of the outlet opening and the end wall has a plurality of arcuate ribs thereon circumferentially spaced apart about said outlet opening and providing a plurality of arcuate gas directing channels for radially guiding the flow of plasma gas in a swirling flow pattern from the entrance to the outlet opening. The nozzle and nozzle mounting components provide an improved arrangement for cooling the torch tip and producing a gas shield about the plasma jet.

Abstract: A plasma torch comprises a tubular nozzle having an end wall and an electrode in the nozzle having a nose end facing the end wall. The nose end and end wall provide a plasma gas chamber, and the end wall has a gas chamber outlet opening extending axially therethrough. The gas chamber has an entrance radially outwardly of the outlet opening and the end wall has a plurality of arcuate ribs thereon circumferentially spaced apart about said outlet opening and providing a plurality of arcuate gas directing channels for radially guiding the flow of plasma gas in a swirling flow pattern from the entrance to the outlet opening. The nozzle and nozzle mounting components provide an improved arrangement for cooling the torch tip and producing a gas shield about the plasma jet.

Abstract: A drag cup for a plasma arc torch is mounted on a sleeve member of the torch tip having a conical outer surface portion converging toward the torch nozzle and electrode assembly. The drag cup includes a mounting end, a conical portion extending along the conical portion of the sleeve member, and an end radially spaced from and surrounding the torch nozzle and including an end wall spaced axially outwardly of the end of the nozzle and having an opening therethrough coaxial with the plasma jet outlet orifice in the nozzle. The opening through the end wall of the drag cup is 3 to 6 times the size of the nozzle orifice and is large enough to provide a shielding gas flow about the plasma jet without disturbing the jet and, at the same time is small enough to protect the nozzle against molten metal blow-back through the opening.

Abstract: A plasma torch comprising an elongated electrically conductive nozzle with an internal, generally cylindrical chamber; an electrically conductive electrode with an elongated, cylindrical nose extending into the cylindrical chamber of the nozzle to define a relatively thin, elongated annular gas passage between the nozzle and the electrode nose, wherein the electrode includes a cylindrical portion above the nose, which portion has axially extending swirl grooves; and, a separate insulator sleeve engaging both the cylindrical portion and the nozzle for holding the electrode nose concentric with said cylindrical chamber of the nozzle. The nozzle includes means for venting a portion of said cooling gas from the relatively thin annular gas passage.

Abstract: A plasma arc torch has a secondary gas flow that is extremely large during piercing of a workpiece to keep splattered molten metal away from the torch and thereby prevent "double arcing". The secondary flow exits the torch immediately adjacent the transferred plasma arc and is an extremely uniform, swirling flow. A swirl ring is located in the secondary gas flow path at the exit point. A prechamber feeds gas to the swirl ring, which is in turn fed through a flow restricting orifice. For certain applications the secondary gas is a mixture of an oxidizing gas, preferably oxygen, and a non-oxidizing gas, preferably nitrogen, in a flow ratio of oxygen to nitrogen in the range of 2:3 to 9:1. Preferably the flow ratio is about 2:1. A network of conduits and solenoid valves operated under the control of a central microprocessor regulates the flows of plasma gas and secondary gas and mixes the secondary gas.

Abstract: Plasma arc or laser cutting uses a mix of reactive and reducing gas flows to cut sheets of stainless steel, aluminum and other non-ferrous metals. The reducing gas flow to the cut varies as a percentage of the total gas flow to maintain a reducing atmosphere down through the cut, but to leave a predominantly oxidizing atmosphere at the intersection of the cut and the bottom surface of the sheet being cut. In plasma arc cutting these flows can also be characterized as either a plasma gas flow, one that forms the arc, or a shield gas flow that surrounds the arc. The reactive gas is preferably a flow of air, oxygen, nitrogen, carbon dioxide or a combination of these gases. The reducing gas is preferably hydrogen, hydrogen 35, methane, or a mixture of these gases. For aluminum, the reactive gas is preferably air or nitrogen and the reducing gas is preferably methane or a mixture of methane and air. In laser cutting the reducing gases such as methane can be used by mixing them with reactive assist gases.

Abstract: An insert securely disposed in a bottom end of an electrode has an exposed emission surface shaped to define a recess in the insert, wherein the recess is initially dimensioned as a function of the operating current level of the torch, the diameter of the insert, and the plasma gas flow pattern in the torch. The electrode has an elongated body formed of a high thermal conductivity material such as copper, and a bore disposed in the bottom end of the body along a central axis. The insert is formed of a high thermionic emissivity material, such as hafnium, and securely disposed in the bore with the emission surface exposed. The emission surface may be initially shaped by removing a predetermined amount of the high thermionic emissivity material from the insert to define a generally concave recess, a generally cylindrical recess or other shapes. When used in a torch, the electrode provides for reduced deposition of the high thermionic emissivity material on the nozzle, thereby reducing nozzle wear in the torch.

Abstract: A plasma arc torch has a secondary gas flow that is extremely large during piercing of a workpiece to keep splattered molten metal away from the torch and thereby prevent "double arcing". The secondary flow exits the torch immediately adjacent the transferred plasma arc and is an extremely uniform, swirling flow. A swirl ring is located in the secondary gas flow path at the exit point. A prechamber feeds gas to the swirl ring, which is in turn fed through a flow restricting orifice. For certain applications the secondary gas is a mixture of an oxidizing gas, preferably oxygen, and a non-oxidizing gas, preferably nitrogen, in a flow ratio of oxygen to nitrogen in the range of 2:3 to 9:1. Preferably the flow ratio is about 2:1. A network of conduits and solenoid valves operated under the control of a central microprocessor regulates the flows of plasma gas and secondary gas and mixes the secondary gas.

Abstract: Plasma arc or laser cutting uses a mix of reactive and reducing gas flows to cut sheets of stainless steel, aluminum and other non-ferrous metals. The reducing gas flow to the cut varies as a percentage of the total gas flow to maintain a reducing atmosphere down through the cut, but to leave a predominantly oxidizing atmosphere at the intersection of the cut and the bottom surface of the sheet being cut. In plasma arc cutting these flows can also be characterized as either a plasma gas flow, one that forms the arc, or a shield gas flow that surrounds the arc. The reactive gas is preferably a flow of air, oxygen, nitrogen, carbon dioxide or a combination of these gases. The reducing gas is preferably hydrogen, hydrogen 35, methane, or a mixture of these gases. For aluminum, the reactive gas is preferably air or nitrogen and the reducing gas is preferably methane or a mixture of methane and air. In laser cutting the reducing gases such as methane can be used by mixing them with reactive assist gases.

Abstract: Circuitry and methods for reducing nozzle wear during starting of a plasma arc torch, even with a large standoff distance from a workpiece is described. The invention features a method of starting a plasma arc torch for cutting a workpiece using a pilot voltage to ionize a plasma gas and generate a pilot arc between an electrode and a nozzle. The method expedites the transfer of the arc from the nozzle to the workpiece by passing a generally smooth signal through the electrode before, during and after the arc transfers to the workpiece. A high frequency high voltage starting circuit is constructed with a pilot arc circuit isolated from a transfer arc circuit. A signal is generated which has a magnitude sufficient to ionizes a plasma gas to generate a pilot arc between the electrode and the nozzle and has a magnitude which generally increases after the pilot arc has been generated in order to expedite the transfer of the arc.

Abstract: An insert securely disposed in a bottom end of an electrode has an exposed emission surface shaped to define a recess in the insert, wherein the recess is initially dimensioned as a function of the operating current level of the torch, the diameter of the insert, and the plasma gas flow pattern in the torch. The electrode has an elongated body formed of a high thermal conductivity material such as copper, and a bore disposed in the bottom end of the body along a central axis. The insert is formed of a high thermionic emissivity material, such as hafnium, and securely disposed in the bore with the emission surface exposed. The emission surface may be initially shaped by removing a predetermined amount of the high thermionic emissivity material from the insert to define a generally concave recess, a generally cylindrical recess or other shapes. When used in a torch, the electrode provides for reduced deposition of the high thermionic emissivity material on the nozzle, thereby reducing nozzle wear in the torch.

Abstract: A high frequency, high voltage starting circuit for a plasma arc cutting torch is constructed and operated with isolation between a pilot arc circuit and a transfer arc circuit. The duration and value of the energy flow in the pilot arc after initiating the HFHV signal are controlled electronically. The maximum value is sufficient to initiate and support the pilot arc and its transfer. The duration is sufficiently long to allow the pilot arc to transfer, but sufficiently short that nozzle wear is reduced. In the preferred form both circuits have a common D.C. power supply and independent surge injector circuits each formed by a resistor and surge capacitor connected in parallel with the power supply. An L-C loop in the pilot arc circuit maintains a generally constant current output on discharge.

Abstract: A plasma arc torch uses a mix of reactive and reducing gas flows to cut sheets of stainless steel, aluminum and other non-ferrous metals. The reducing gas flow to the cut is varied as a percentage of the total gas flow to maintain a reducing atmosphere down through the cut, but to leave a predominantly oxidizing atmosphere at the intersection of the cut and the bottom surface of the sheet being out. These flows can also be characterized as either a plasma gas flow, one that forms the arc, or a shield gas flow that surrounds the arc. The reactive gas is preferably a flow of air, oxygen, nitrogen, carbon dioxide or a combination of these gases. The reactive gas is usually in the plasma gas flow, whether alone or mixed with other gases. The reducing gas is preferably hydrogen, hydrogen 35, methane, or a mixture of these gases. For aluminum, the reactive gas is preferably air or nitrogen and the reducing gas is preferably methane or a mixture of methane and air.

Abstract: A plasma arc torch has a secondary gas flow that is extremely large during piercing of a workpiece to keep splattered molten metal away from the torch and thereby prevent "double arcing". The secondary flow exits the torch immediately adjacent the transferred plasma arc and is an extremely uniform, swirling flow. A swirl ring is located in the secondary gas flow path at the exit point. A prechamber feeds gas to the swirl ring, which is in turn fed through a flow restricting orifice. For certain applications the secondary gas is a mixture of an oxidizing gas, preferably oxygen, and a non-oxidizing gas, preferably nitrogen, in a flow ratio of oxygen to nitrogen in the range of 2:3 to 9:1. Preferably the flow ratio is about 2:1. A network of conduits and solenoid valves operated under the control of a central microprocessor regulates the flows of plasma gas and secondary gas and mixes the secondary gas.

Abstract: Plasma arc or laser cutting uses a mix of reactive and reducing gas flows to cut sheets of stainless steel, aluminum and other non-ferrous metals. The reducing gas flow to the cut varies as a percentage of the total gas flow to maintain a reducing atmosphere down through the cut, but to leave a predominantly oxidizing atmosphere at the intersection of the cut and the bottom surface of the sheet being cut. In plasma arc cutting these flows can also be characterized as either a plasma gas flow, one that forms the arc, or a shield gas flow that surrounds the arc. The reactive gas is preferably a flow of air, oxygen, nitrogen, carbon dioxide or a combination of these gases. The reducing gas is preferably hydrogen, hydrogen 35, methane, or a mixture of these gases. For aluminum, the reactive gas is preferably air or nitrogen and the reducing gas is preferably methane or a mixture of methane and air. In laser cutting the reducing gases such as methane can be used by mixing them with reactive assist gases.