| 摘要 |
PURPOSE:To perform all position plasma welding of fixed tubes at high accuracy, by attaching a ring having sectional area larger than the thickness of fixed tubes and a step for alignment to fixed tubes so that the step protrudes from fixed tubes, and then welding them. CONSTITUTION:A ring 9C is attached to the end of fixed tubes 8A, 8B to be welded provided to arrest rotation. The ring 9C has radial sectional area larger than the thickness D of fixed tubes 8A, 8B, and steps 10A, 10B for centering are provided on the outer periphery and inner periphery respectively. The steps 10A, 10B are made to protrude from inner wall and outer wall of fixed tubes 8A, 8B. By performing plasma keyhole welding under this condition, depression of uranami of welding bead and undercut can be prevented. Dripping of molten metal can be prevented by changing welding current intermittently and alternately to high and low. |
