Press brake and method of operating press brake

A method of operating a press brake,

• the press brake including:
• a conveying mechanism that conveys a workpiece;
• a die including a pair of shoulder portions and a groove portion located between the pair of shoulder portions, the pair of shoulder portions being arranged away from each other in a conveying direction of the workpiece and supporting a rear surface of the workpiece;
• a backup plate that extends on the pair of shoulder portions, covers the groove portion, and is interposed between the die and the workpiece;
• and
• a punch that moves relative to the die and presses the workpiece, wherein the backup plate includes a laminated structure in which plates are stacked on each other, and among the plates included in the backup plate, an outer-surface plate that is a plate located closest to the punch includes a curved portion that both edge portions of the outer-surface plate in the conveying direction of the workpiece curve in a direction away from the punch, and both edge portions extend past all of the plates of the backup plate, and the curved portion covers edge portions of the plates in the conveying direction,
• the method comprising:
• conveying the workpiece and stopping conveying the workpiece at a position on the backup plate and right under the punch;
• and
• moving the punch relative to the die and pressing the workpiece within an elastic deformation region of the backup plate.