Hypertherm, Inc.

Hyperthem, Inc.

Jeffrey L Peterson

John Sobr

Lifeng Luo

Richard W Couch, Jr

Zhipeng Lu

Dennis M Borowy

William V Bailey

Norm LeBlanc

Timothy M Brewer

Christopher S Passage

David J Rhodes

Jeffrey S Ryan

David J Holden

A torch height control system maintains a substantially constant operating parameter of the arc during processing of a workpiece by measuring the operating parameter, comparing the operating parameter to a reference value to generate a deviation, adjusting a standoff between the torch and the workpiece by moving the torch relative to the workpiece at a rate which increases with an increase in the deviation to minimize the deviation, and clamping the rate of torch movement relative to the workpiece when the deviation exceeds a predetermined value.

Plasma arc torch position control

A plasma arc torch system includes a plasma arc torch and a positioning apparatus for automated processing of workpieces. In order to maintain consistent cut quality, a controller maintains arc voltage at a predetermined reference value by controlling a standoff between the torch and the workpiece. To prevent contact between the torch and workpiece during kerf crossings and to maintain an optimum standoff during acceleration and deceleration, standoff control override algorithms are implemented in the controller. Additionally, a contact sensing apparatus is provided to automatically retract the torch in the event of contact with the workpiece during processing.

A liquid cooled plasma arc cutting torch system includes a plasma arc torch, a torch receptacle and a cooling system. The torch is removably mounted to the receptacle. The cooling system includes a liquid storage tank, supply and return lines providing fluid communication paths between the tank and the receptacle and a pump for pumping the cooling liquid from the tank through the supply line, the receptacle, the torch and the return line. A valve coupled to the return line includes a nozzle that directs liquid toward an inside top surface of the tank. A flow restriction member may be provided to equalize pressure in the supply with atmospheric pressure when the pump is not operating. A pressurized gas source may be utilized to substantially clear the receptacle, torch and return line of liquid when the pump is not operating.

Liquid cooled plasma arc torch system and method for replacing a torch

An arc control circuit in a plasma arc torch, having an electrode and a nozzle, maintains a plasma arc during operation of the torch. The circuit includes a power supply electrically coupled to the electrode, nozzle and a workpiece. A logic device opens a power switch electrically coupling the nozzle to the power supply, disconnecting the nozzle from the supply, when a transferred arc is formed between the electrode and the workpiece. An amplifier is electrically connected to the power supply. The amplifier compares a sensed current to an operating current. The amplifier increases the output voltage of a power supply to maintain the operating current in coordination with an increasing distance between the workpiece and the torch. A comparator is electrically connected to a logic device and compares the output voltage of the power supply to a maximum voltage. When the output voltage of the power supply exceeds the maximum voltage, the comparator sets the logic device. The logic device generates an output signal to close the power switch and reconnect the nozzle to the power supply, thereby initiating switching of the arc from the workpiece to the nozzle.

Circuitry and method for maintaining a plasma arc during operation of a

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. The signal magnitude is, however, low enough to minimize transfer of the arc back to the nozzle.

Plasma arc cutting torch ignition circuit and method providing a forced

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.

Plasma arc torch ignition circuit and method

A high frequency, high voltage starting circuit for a plasma arc cutting torch is operated in pulses to restart the torch if an initial arc extinguishes before the arc transfers to the workpiece. The starting circuit includes a D.C. power supply with its negative output connected to an electrode of the torch. A positive output is connected to a nozzle, and at a higher positive voltage, to a workpiece. A surge injector circuit of a resistor and surge capacitor is connected in parallel with the power supply to supply current to the arc as soon as breakdown occurs. The duration of the interval between restart pulses is sufficient to allow the surge injector circuit to recharge to a value that will reliably restart the arc as the power supply ramps up to a steady state pilot arc current.

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Lebanon, NH, United States of America

Jeffrey L Peterson