| 摘要 |
PROBLEM TO BE SOLVED: To control a weld deposit height formed by a following torch to be constant all the time, even when welding speed of a preceding torch is changed.SOLUTION: The welding head includes the preceding torch and the following torch loaded on a carrier, which moves on a travelling rail arranged in a circumferential direction along edge portions of fixed pipes to be butt-welded. While the carrier is moved along the travelling rail in the circumferential direction, the butting edge portions are arc-welded at a designated welding speed so that a weld deposit amount for a unit welding length is kept constant. When the welding speed of the preceding torch is changed at a position of external disturbance, wire feeding speed of the following torch is changed so that the weld deposit amount for a unit welding length stays the same as that prior to the change, and wire projection length L from the tip of torch 13 is controlled so that welding current stays the same as that prior to the change. |
