A bending method feeds a long workpiece material made of metal and having a plurality of thickness portions disposed at different angles between rollers and bends the workpiece material. An initial shape of the workpiece material is a straight line or a bend with a bend radius larger than a target bend radius, a thickness of a cross section of the workpiece material along a bend radius direction is set to increase from an inner side toward an outer side of the bend radius direction, the workpiece material is fed between the rollers and rolled in a way that an amount of rolling in a region corresponding to the outer side of the bend radius direction is larger than an amount of rolling in a region corresponding to the inner side, and the workpiece material is bent to have the target bend radius from the initial shape.

A bending method feeds a long workpiece material made of metal and having a plurality of thickness portions disposed at different angles between rollers and bends the workpiece material. An initial shape of the workpiece material is a straight line or a bend with a bend radius larger than a target bend radius, a thickness of a cross section of the workpiece material along a bend radius direction is set to increase from an inner side toward an outer side of the bend radius direction, the workpiece material is fed between the rollers and rolled in a way that an amount of rolling in a region corresponding to the outer side of the bend radius direction is larger than an amount of rolling in a region corresponding to the inner side, and the workpiece material is bent to have the target bend radius from the initial shape.

A method for rolling a Z-section sheet pile comprises rolling a curved preform of a web (16) in successive roll gaps defined by at least one roll pair comprising a grooved upper roll (26) and a grooved lower roll (28), wherein: a first corner (18) and an adjoining first part of the curved preform of the web (16) are formed in a first groove (42) of an upper roll (26); and a second corner (20) and an adjoining second part of the curved preform of the web (16) are formed in a first groove (46) of a lower roll (28). In the last roll gaps forming the curved preform of the web (16), the diameter of the lower roll (28) decreases in a discontinuous manner in the interval between the first groove (42) in the upper roll (26) and the first groove (46) in the lower roll (26), and the diameter of the upper roll (26) increases in this interval in a complementary manner.