PURPOSE: To provide the plasma arc torch with high reliability by fixing an outside cooling path joining block on an outer wall of a plasma arc torch main body via packing surrounding a water supply port and a drain port of a cooling medium. ;CONSTITUTION: A first gas is carried to a first nozzle 4 outside a negative electrode 3. A second gas is carried to a second nozzle 5 outside the first nozzle 4. The first and second nozzles 4 and 5, and the negative electrode 3 are cooled by the cooling medium carried 4o a cooling path 11. The cooling path 11 is joined mechanically by the outside cooling path joining structure. The outside cooling path joining structure is then formed of the outside cooling path block 2 of electrical insulating material. The block 2 is provided with the water supply port 16 and the drain port 17 of the cooling medium and cooling medium paths to connect these. The outside cooling path joining block 2 is then fixed on the outer wall of the plasma arc torch 1 main body via the packing surrounding the water supply port 16 and the drain port 17 of the cooling medium. Consequently, the decrease of the service life of the plasma arc torch due to electric corrosion is prevented.;COPYRIGHT: (C)1993,JPO&Japio
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