Hypertherm, Inc.

Timothy M Brewer

Richard W Couch, Jr

Zhipeng Lu

John Sobr

Jeffrey L Peterson

Elizabeth B Hackett

A plasma arc torch apparatus and method for cutting or marking a workpiece includes a torch having an electrode and a nozzle coupled to a power supply, and a plasma gas source coupled to a fluid line for delivering plasma gas to the torch. A flow restriction member is disposed in the fluid line adjacent the torch and causes the pressure of the plasma gas in the torch to gradually increase during start up thus creating a stable plasma arc. A three-way valve is disposed in the fluid line downstream of the flow restriction member and has an inlet, a torch outlet, and a vent outlet. The inlet is in fluid communication with the torch outlet for delivering plasma gas to the torch when the valve is in the open position, and the torch outlet is in fluid communication with the vent outlet when the valve is in the vent position, for rapidly dissipating the gas in the plasma chamber of the torch to atmosphere after the arc has been extinguished. The rapid reduction of the gas pressure in the torch reduces the cycle time, enabling the torch to be restarted more quickly after completion of a prior cutting cycle.

Apparatus and method for starting and stopping a plasma arc torch used

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.

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Lebanon, NH, United States of America

Timothy M Brewer