| 摘要 |
PROBLEM TO BE SOLVED: To provide a cooling structure of a plasma torch for emitting a jet of gas for plasma formation, which prevents deformation of a screw part by adequately maintaining rigidity while strengthening cooling of the screw part for fixing an electrode end 34 and enhances the rigidity for holding the electrode end 34 without enlarging an outside diameter of the whole of the plasma torch. SOLUTION: The cooling structure of the plasma torch is characterized as follows: a current-carrying copper tube 10 is disposed in the center of the plasma torch; an end of the copper tube 10 is surrounded by a closed-end cylindrical electrode 8, into which the copper tube 10 is screwed; and the copper tube 10 is provided with a cooling channel 16 in a thickness part near a screwing part 17. The cooling channel 16 is at least one through hole, both ends of which have opening parts provided in an outer periphery of the copper tube 10. One opening is located near one end of the screwing part 17, and the other opening is located near the other end of the screwing part 17. The plasma torch can be used for a device for heating molten steel in a tundish.
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