Abstract: A detection system for a cutting torch for use in connection with a workpiece. The detection system has an electrode and a tip. A housing supporting the tip and the electrode provides relative movement therebetween and allows electrical contact between the tip and the electrode. A sensor circuit senses when the electrode and the tip are in electrical contact. The sensor circuit generates a switch control signal when the electrode and tip are in electrical contact. A power supply provides a first voltage and a second voltage such that a potential voltage difference is established between the electrode and the and/or workpiece. A magnitude of the first voltage is less than a magnitude of the second voltage.

Abstract: A power supply apparatus includes a housing containing therein a component which generates heat when operating, a fan for cooling the heat-generating component, and a driving unit for driving the fan. The housing also contains therein a temperature detector for detecting the temperature in the housing and providing a detected-temperature representing signal. In response to the detected-temperature representing signal, a control unit provides the driving unit with a control signal to change the rotation speed of the fan.

Abstract: An electronic circuit for a plasma arc torch that initiates the transfer of a pilot arc into an operating arc before operating current is sensed in a workpiece. The electronic circuit includes a power circuit output inductor, and a pilot circuit having a disconnect in series with the pilot electrode of the plasma torch. An oscillator is coupled to the disconnect to periodically open-circuit the pilot circuit before current is detected in the workpiece by a current sensor. The periodic cessation of current caused by the disconnect causes the output inductor to create a voltage spike that assists in the transfer by attempting to establish the operating arc between the electrode and the workpiece. Optionally, a pilot inductor in the pilot circuit provides transitory power to sustain the pilot arc during the time the pilot current source is ceased, should arc transfer not occur.

Abstract: A plasma arc cutting tip is provided having chamfer tip edge so that it can be easily moved and dragged across a workpiece for drag cutting and having counterbored plasma arc exit orifice which keeps the exit orifice off the workpiece so that the tip can tolerate plasma arc deflection without suffering tip damage or tip failure.

Abstract: Plasma cutting apparatus (10) for use in cutting a material (M). A torch (12) cuts the material. A control unit (14) controls the cutting operation performed by the torch and includes a control module (16) in which the control unit is housed. At least one power unit (18) supplies power to the cutting torch, the application of this power being controlled by the control unit. Each power unit includes a power module (24) in which the power unit is housed. A cooling unit (54) for cooling the torch is also available. The cooling unit includes a cooling module (56). The control module, power module(s), and coolant module are removably stackable one on top of the other.

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.

Abstract: This plasma arc torch includes an improved front end assembly to create an improved gouge path when compared with prior art plasma arc gougers. The front end assembly includes a unique secondary gas nozzle for distribution of the secondary gas in a partial radial blanket up to 300.degree. around the plasma. Conventional nozzles distribute the seondary gas in a total, 360 degree, blanket around the plasma. An improved tip design is believed to develop an enlarged plasma stream to further enhance the gouging process.

Abstract: An electrode used in a plasma-arc torch has ridges formed on the side surface thereof for initiating a pilot arc. The required voltage for initiating a pilot arc is substantially reduced by employing this type of electrode. The ridges have much smaller radii of curvature which substantially enhance the local electric field strength responsible for creating the pilot arc discharge. The ridges are oriented substantially along the flow lines of the plasma gas so as to create the least disturbance. In one embodiment with spiral gas flow, this results in helically oriented ridges. In another embodiment with straight gas flow, the ridges are parallel to the longitudinal axis of the electrode.

Abstract: A plasma-arc cutting torch housing defines a chamber which has an outlet at the end of the housing. The torch also includes an electrode in the chamber near the outlet and a provision in the chamber for separating the gas flowing towards the outlet of the housing into a primary gas flow adjacent to the electrode for generating a plasma and a secondary gas flow away from the electrode for cooling the torch and the workpiece. The electrode has a centrally disposed bore therethrough for conveying gas. An insert in the workpiece end of the electrode burns away so as to expose the essentially disposed bore therethrough, thereby automatically quenching operation of the plasma arc so as to minimize damage to the torch. In the preferred embodiment, the electrode has a stepped centrally disposed bore which stops short of the insert. In an alternate embodiment, the stepped bore extends through to the insert and accommodating insert bore.

Abstract: A plasma-arc torch is provided having a spring loaded ejector mechanism for expelling the electrode and thereby breaking off electrical contact so as to prevent operation of the torch when necessary parts are not in place.

Abstract: A plasma-arc torch includes an interlock in the form of a sliding gas valve which permits interruption of torch operation by closing off fluid flow through the torch when necessary parts such as the electrode, tip, fluid distributor, and/or cup are not in place.

Abstract: A plasma-arc torch interlock with pressure sensing is provided. A pressure sensor is included within the conduit supplying working fluid to a plasma-arc torch. By sensing a decrease in pressure of the working fluid which is caused by a necessary part being not in place, a control circuit shuts off power to the torch. In a second embodiment, two conduits are provided to supply fluid to the torch. One conduit supplies the primary working fluid to create the plasma-arc while the other supplies secondary flow for purposes of cooling.

Abstract: A plasma-art torch interlock with flow sensing is provided. A flow rate sensor is included within the conduit supplying working fluid to a plasma-arc torch. By sensing an increase in flow rate of the working fluid which is caused by a necessary part being not in place, a control circuit shuts off power to the torch. Pressure in the conduit may also be sensed and the power to the torch shut down if a minimum pressure needed for torch operation is not achieved. In a second embodiment, two conduits are provided to supply fluid to the torch. One conduit supplies the primary working fluid to create the plasma-arc while the other supplies secondary flow for purposes of cooling.

Abstract: The present invention minimizes shock hazard in using a touch start plasma torch. The resistance between the torch tip and the workpiece is compared to a predetermined value set by estimating the resistance between a person's hand to ground under the most unfavorable conditions. In the preferred embodiment, such comparison is performed by supplying an AC voltage to a resistor in series with a torch tip, the resistor having a resistance equal to the predetermined value. The peak voltage at a point in the circuit connection between the resistor and torch tip is sensed and if such peak is less than half of the peak voltage of the AC voltage supplied to the resistor and torch tip, the resistance between the torch tip and ground is less than the predetermined value and a control signal will be generated.

Abstract: In the plasma arc torch of this invention the same gas may be used for generating a plasma and for secondary gas flow for cooling the torch and the workpiece. A torch housing defines a chamber which has an outlet at the end of the housing. The torch also includes an electrode in the chamber near the outlet and means in the chamber for separating the gas flowing towards the outlet of the housing into a primary gas flow adjacent to the electrode for generating a plasma and a secondary gas flow away from the electrode for cooling the torch and the workpiece. In the preferred embodiment, air may be used for both the plasma forming gas and the secondary gas and the electrode has a halfnium insert. The torch has a torch tip adjacent to the electrode and the torch may be started without a pilot arc by touching the workpiece with the torch tip.

Abstract: A plasma arc cutting torch housing defines a chamber which has an outlet at the end of the housing. The torch also includes an electrode in the chamber near the outlet and means in the chamber for separating the gas flowing towards the outlet of the housing into a primary gas flow adjacent to the electrode for generating a plasma and a secondary gas flow away from the electrode for cooling the torch and the workpiece. The electrode has a centrally disposed bore therethrough for conveying gas. Inserts in the bore at opposite ends of the electrode burn away so as to expose the centrally disposed bore and thereby automatically quench operation of the plasma arc so as to prevent damage to the torch. In the preferred embodiment, the electrode has a centrally disposed transverse bore and a pair of transverse bores intermediate the central bore and the electrode ends. In an alternate embodiment, the pair of transverse bores are eliminated and gas is conducted by means of an annular gas distributor.