| 摘要 |
PURPOSE:To prevent generation of distortion and a crack, by pinch-installing a backing metal faced to crossing bottom plate weld lines, like a sandwich by the upper and lower plates, and constituting the backing metal and the lower plate so as to be freely slidable. CONSTITUTION:As for a weld line 7, tack welding is executed from the front prior to regular welding, and subsequently, regular welding is executed, but as for the part of an upper plate 6', grooves of unit bottom plates 5, 5 and the upper plate 6' are welded, and as for the part separated from the upper plate 6', the unit bottom plates 5, 5 and a backing metal 8 are welded. Expansion and contraction of the unit bottom plates 5, 5... and expansion, contraction and deformation of the upper plate 6' and the backing metal 8, which follow welding of the weld line 7 are absorbed by free slide between the upper plate 6' and the backing metal 8, and between the backing metal 8 and the lower plate 6, and distortion in case of welding is scarcely generated. |
