| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact and inexpensive centering jig for tube welding having an excellent operability. SOLUTION: Two screw bars 20, 30 are independently and rotatably arranged in a file in the central part of a housing 10 which is inserted with a sufficient gap into the inside of tube bodies A, B to be welded. The inner side screw bar 30 is rotated with a rotary type operating rod 40 which is arranged along two screw bars 20, 30. Plural number of first movable members 50 and second movable members 60, which are transferred in the radial direction accompanying each rotation of the screw bar 20 and the screw bar 30, are provided in plural positions of each outer peripheral side of the screw bar 20 and the screw bar 30. A head 70 served also as a holding body of a backing member 80 is attached to each of the first movable members 50. The housing 10 is fixed to the end part of the tube body A by inserting the inner side end part of the housing 10 into the end part of the tube body A and by transferring the second movable members 60 to the outside in the radial direction. After being fixed, the tube body B is butted against the tube body A, the first movable members 50 are transferred to the outside in the radial direction and pressurized against the inner surfaces of butting parts of the tube bodies A, B, and whereby the tube bodies A, B are concentrically connected.
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