Abstract: A dual mode plasma arc torch is provided that preferably comprises a start cartridge disposed between an electrode and a tip. In one form, the start cartridge comprises an initiator that is in electrical contact with the electrode and that is resiliently biased into contact with the tip, such that when the plasma arc torch is in a contact start mode, the initiator is movable against the resilient bias to separate from the tip and establish a pilot arc between the initiator and the tip. Further, when the plasma arc torch is in a high frequency start mode, the start cartridge spaces the tip from the electrode such that a pilot arc is established between the electrode and the tip. In other forms, a contact start torch is provided that is operable under high frequency, and conversely, a high frequency start torch is provided that is operable under low voltage.

Abstract: A quick disconnect for use in a plasma arc torch is provided that comprises a plug housing and a mating socket housing, a locking ring disposed around the plug housing secures the plug housing to the socket housing. A negative lead gas carrying pin is disposed within the plug housing, and a mating main power socket is disposed within the socket housing for the purpose of conducting both gas and electricity from a power supply to a plasma arc torch. Further, the negative lead gas carrying pin and mating main power socket are positioned off-center in order to provide additional volume for a plurality of signal conductors disposed within each housing, along with a pilot return conductor. Additionally, both the plug housing and the socket housing define a D-configuration in order to properly align the housings and conductors disposed therein, among other novel features of the present invention.

Abstract: A contact start plasma torch and method of starting the torch includes a negatively charged cathode body and a positively charged anode body. A conductive element in the torch is constructed of an electrically conductive material and is free from fixed connection with the cathode body and the anode body. The torch is operable between an idle mode wherein the conductive element provides an electrically conductive path between the cathode body and the anode body and an pilot mode wherein a pilot arc is formed between the conductive element and at least one of the cathode body and the anode body. The pilot arc is blown by working gas flowing through the torch toward an exit orifice of the torch whereby the working gas is exhausted from the torch in the form of an ionized plasma.

Abstract: A trigger system for operating a plasma arc torch is provided that comprises a selector that operates between at least a first operating position and a second operating position, wherein the first operating position operates the plasma arc torch in a first mode to deliver gas to the plasma arc torch, and the second operating position operates the plasma arc torch in a second mode to deliver the gas and electric power to the plasma arc torch. Further, the selector comprises a neutral position that selects a neutral mode in which delivery of gas and electric power to the plasma arc torch is inhibited. The selector is preferably disposed within a housing of the plasma arc torch and is slidably operable between the first operating position, the second operating position, and the neutral position.

Abstract: Devices and methods are provided that control gas flow to a plasma arc torch local to a torch handle. Generally, a plasma arc torch is provided that comprises a gas control device operable with a torch lead and a torch head, and an activation member operable with the gas control device. Accordingly, the activation member activates the gas control device such that gas flow is supplied from the torch lead to the torch head, and the activation member deactivates the gas control device such that the gas flow is terminated. Further, the activation member may comprise a trigger system, a button, or a safety member, among others. Moreover, the gas control device may comprise a gas control valve or a switch that activates a gas control device disposed within a power supply, among others.

Abstract: A quick disconnect for use in a plasma arc torch is provided wherein a plurality of connections disposed therein are configured such that the connections break in a specific order when the quick disconnect is disengaged. Preferably, the quick disconnect comprises a plurality of signal pin connections, a pilot return connection, a fluid connection, and a main power connection. Accordingly, the signal pin connections break before the pilot return connection, the fluid connection, and the main power connection. Further, the pilot return connection breaks before the fluid connection and the main power connection, and the fluid connection breaks before the main power connection as the quick disconnect is disengaged. As a result, a safer quick disconnect in which both gas and electric power are conducted is provided by the present invention.

Abstract: A solenoid control and safety circuit suitable for use in connection with contact start, plasma-arc torches. The system monitors a voltage to determine when to open an air control solenoid as part of a contact starting process. If a proper voltage is sensed, a gas solenoid is opened to allow airflow to separate the contact starting elements. The system also includes a circuit that monitors a gas pressure switch to determine whether sufficient pressure exists to separate the contact start elements after a contact start process has been initiated. The circuit removes power if it senses insufficient pressure. Also disclosed is a circuit that monitors a differential voltage between the electrode and the tip to determine if the elements remain in contact after airflow has been provided to the torch head.

Abstract: A solenoid control and safety circuit suitable for use in connection with contact start, plasma-arc torches. The system monitors a voltage to determine when to open an air control solenoid as part of a contact starting process. If a proper voltage is sensed, a gas solenoid is opened to allow airflow to separate the contact starting elements. The system also includes a circuit that monitors a gas pressure switch to determine whether sufficient pressure exists to separate the contact start elements after a contact start process has been initiated. The circuit removes power if it senses insufficient pressure. Also disclosed is a circuit that monitors a differential voltage between the electrode and the tip to determine if the elements remain in contact after airflow has been provided to the torch head.

Abstract: A plasma torch and method for cutting a workpiece under water directs a primary gas through a primary gas flow path in the torch to a central exit opening of the torch disposed on a longitudinal axis of the torch for exhaustion from the torch onto the workpiece in the form of an ionized plasma. The workpiece is submerged in water while the plasma torch is operated in closely spaced relationship with the workpiece to direct the ionized plasma upon the workpiece. A secondary gas flow path in the torch receives a secondary gas separate from the primary gas and directs it through the torch. Concentrically arranged first and second sets of secondary exit openings are disposed in the torch separate from the central exit opening and in generally radially spaced relationship with the longitudinal axis of the torch. The secondary exit openings exhaust secondary gas from the torch in a direction generally toward the workpiece.

Abstract: An aluminum alloy fluid heat exchanger comprises first and second elongate, generally flat, aluminum alloy fluid heat exchanger tubes, each having an upper and a lower surface and having a fluid port inlet and a fluid port outlet. The first tube has a series of small protrusions formed at its lower surface and the second tube has a matching series of protrusions formed at its upper surface, the first tube being stacked on top of the second tube with the protrusions on the first tube in contact with the protrusions on the second tube. A thin sheet of a dissimilar metal, preferably cold rolled steel having a thickness of about 0.3 millimeters is installed between the protrusions on the first and second tubes. The protrusions provide a spacing of at least about 0.42 millimeters between major portions of the first and second heat exchanger tubes. A corresponding method of constructing an aluminum alloy heat exchanger is described.

Abstract: A plasm-arc torch system, a circuit, and a method for controlling a pilot arc. A rate of change sensor, such as a dv/dt sensor, monitors the output of an error amplifier to determine whether to close a switch to re-attach a pilot arc before a transferred arc becomes extinguished. The switch selectively connects a tip into a circuit path with an electrode and a power supply to allow the pilot arc to form between the tip and the electrode. The error amplifier preferably provides an error signal for use by a pulse-width modulator for providing a current regulated power supply capability. The power supply preferably regulates the output current to a first level when a pilot arc is present, and to a second mode when a transferred arc is present. The pilot arc may also be re-attached between the tip and the electrode by use of a pilot regulator that attempts to maintain the current flowing through the tip at an intermediate level between the first level and the second level.

Abstract: A contact plasma-arc torch having a parts-in-place safety reset circuit and method. The torch includes an electrode and a tip. A safety reset circuit monitors parameters associated with the electrical relationship between the electrode and the tip to determine whether the tip and/or electrode are properly installed. The circuit also monitors an electrical relationship associated with the workpiece to detect when current is flowing in the workpiece when such current is not expected. The torch power supply and associated circuitry includes a soft start capability whereby the full power output of the power supply is supplied to the electrode over time due to the soft start characteristic of a soft start circuit. If the safety reset circuit detects that the tip and/or electrode arc not properly installed, or that current is flowing in the workpiece when such current is not expected, the safety reset circuit resets the soft start circuit.

Abstract: A plasma arc torch and method for cutting a workpiece in which the torch has a primary gas flow path for receiving a primary working gas and directing it through the torch to a central exit opening of the torch for exhaustion from the torch onto the workpiece in the form of an ionized plasma. A secondary gas flow path in the torch receives a secondary gas separate from the primary working gas and directs it through the torch. The primary gas flow path is in fluid communication with the secondary gas flow path substantially upstream of the central exit opening of the torch to bleed primary working gas in the primary gas flow path into the secondary gas flow path for admixture therewith to form a secondary gas mixture to be exhausted from the torch.

Abstract: A plasma arc torch has a cathode and electrode having connecting ends configured for a coaxial telescoping connection with one another on a central longitudinal axis of the torch. The connecting ends have interengageable detents thereon, with at least one of the detents being movable in a generally radial direction relative to the central longitudinal axis of the torch between an undeflected state and a deflected state. The at least one detent is movable from the undeflected state to the deflected state when the cathode and electrode are telescoped one into the other, and is movable from the deflected state back toward the undeflected state when the cathode and electrode are further telescoped tc, a point where the detents on the cathode and electrode are generally axially aligned. In this position, the at least one detent is engageable with the other detent to interconnect the cathode and electrode and inhibit axial movement of the electrode away from the cathode.

Abstract: A pilot arc circuit for a plasma torch establishes a pilot arc current in the channel between the torch electrode and torch tip at a first target level which is greater than a predetermined minimum current sufficient to maintain a stable pilot arc. After a period of time following pilot arc initiation, the pilot arc current is reduced to a second target level which is greater than or equal to the predetermined minimum current so that damage to the torch is reduced by minimizing wear on the parts. The pilot arc current is established and maintained as a function of a pilot arc reference signal. Pulsing the pilot arc current assists in main arc transfer and enhances pilot arc stability.

Abstract: A plasma arc torch having new electronic circuit concepts wherein main current regulated power means regulates the pilot current prior to main arc transfer. Further, the circuit may contain two inductors to which DC current initially flows but is interrupted upon main arc transfer such that one inductor maintains the pilot arc while the current in the second inductor forces the establishment of the transferred arc. Also, advantages are presented in pulsing the cutting arc as well as pulsing the pilot arc.