Abstract: A welder for a metal rolling system, which is disposed in the metal rolling system and is configured to perform spot-welding on a product strip, includes a back bar disposed below the pass line and welding guns disposed above the pass line to perform series welding for welding a plurality of points at one time.

Abstract: A welder for a metal rolling system, which is disposed in the metal rolling system and is configured to perform spot-welding on a product strip, includes a back bar disposed below the pass line and welding guns disposed above the pass line to perform series welding for welding a plurality of points at one time.

Abstract: To provide a roll, a rolling mill and rolling method capable of not only effectively correcting the plate crown of a material to be rolled but also reducing the edge drop and preventing a roll from damage caused by the increase of the local line pressure between the rolls. A roll crown is formed by a continuous curve having a local maximum point and a local minimum value point where the central region held between the local maximum point and the local minimum point represents one function and the end region from the local maximum point to the nearer roll end represents another function having an inclination of steeper gradient (or having a radius decreasing more sharply toward the roll end) than that of the extension of the function in the central region.