TACK WELDING METHOD

PURPOSE:To suppress lounge mismatching to the minimum by giving a mechanical binding force to a lounge material, and specifying conditions of a tack welding, when tacking vertically the lounge material onto a horizontal skin material by a horizontal fillet welding. CONSTITUTION:A lounge material 5 is placed vertically on a skin material 4 provided horizontaly so as to be movable in the direction as indicated with an arrow, and a welding device 6 for bringing the material 5 to a horizontal fillet tack welding against the material 4 is provided. Also, vertical binding devices 8, 9 for pressing the upper face of the material 5 from the upper part, and horizontal binding devices 10, 11 for pressing both side faces before and behind the material 5 are provided before and behind a welding torch 7 in the direction of a weld line. In this state, the material 4 and 5 are moved in the direction as indicated with an arrow, and the material 5 is tack-welded by giving a mechanical binding force by the devices 8-11, respectively. In this case, the tack welding is executed under each condition that a welding heat input quantity is Q=