| 摘要 |
PURPOSE:To cool gradually a welded joint part to improve the press-moldability, by forming a supporting plate, where two steel plates butted to each other are put, and press plates, which press both steel plates to the supporting plate to fix them, with heat insulating materials. CONSTITUTION:At a welding time, two steel plates 41 and 42 are butted to each other and are put on a supporting plate 1 to form a prescribed gap (g) on the aperture of a groove 2. Steel plates 41 and 42 are pressed by press plates 31 and 32 from above, and steel plates 41 and 42 are fixed onto the supporting plate 1 to hold the gap (g). Next, a roller 5 of a welding machine is placed in the front side in the welding direction, and a welding head 8 is placed in the back side in the welding direction, and they are put on the butt part of steel plates 41 and 42. Inert gas is jetted toward the groove 2 to fill up the groove 2 and a cover 9 with inert gas, and the butt part is welded from one end to the other while intercepting air. At this time, heat retained in the joint part is escaped gradually to steel paltes 41 and 42 by the heat insulating effect of the supporting plate 1 and press plates 3 and 3, and the joint part is cooled gradually to suppress the rise of hardness. |
