| 摘要 |
PURPOSE:To obtain multilayers of beads without any defect by increasing welding current at a specified rate during the time right after one bead layer is formed approximately over the entire circumference in a groove until a fresh bead beings to be formed continuously in the upper part of the bead. CONSTITUTION:A weld bead layer 18a for the 1st layer is formed approximately over the entire circumference of a weld groove face 10 of pipe along the inside circumference 14 thereof and thereafter a bead layer 18b for the 2nd layer is continuously formed so as to ride on the upper part at the start point 16 for said welding. Welding is performed during this time at the specified current I from the point of the time 24 when the layer 18a is begun to be formed. The welding current is increased to I+alpha during the time since the point of the time 26 right after the end of formation of the layer 18a till the point of the time 28 when a bead layer 18b begins to be formed in continuation with the upper part of said layer. The rate of the increase of the current is about 10-20% and the moving distance of the torch is about several mm.. The defect in the joint where the weld bead layers overlap on each other is thus thoroughly eliminated. |
