METHOD AND APPARATUS FOR BONDING METAL PLATES

A pair of upper and lower pressure rollers (3, 4) is disposed so that their axes (15, 16) are tilted in a horizontal plane in respective directions opposite to each other with respect to a straight line perpendicular to a welding line of a joint portion J. The pressure rollers (3, 4) are positively driven by corresponding electric motors (63, 64) to thereby roll the joint portion. Thus, steps defined at the joint portion can be smoothed and a step gradient can be reduced to ensure a high degree of joint strength. The respective tilting directions of the axes (15, 16) of the pressure rollers (3, 4) are such that respective travel-directional portions (3A, 4A) of the pair of pressure rollers (3, 4) face in the horizontal plane toward the corresponding directions opposite to the extending directions of metal plates (5, 6) concerning a metal material with which the pressure rollers (3, 4) first come into contact. Thus, it is possible to prevent a step portion from being interfolded into the base material of the metal plates (5, 6). Thus, a stress concentration factor can be reduced and the steps S defined at the joint portion can be smoothed, thereby enhancing the quality of the joint portion.