1. Field of the Invention
The present invention relates to a press brake system for bending, flanging, folding and forming a piece of sheet metal, particularly an elongate and curved worksheet, including a punch and a matrix which cooperate in a linear bending zone and at least one of which is movable towards the other and in the opposite direction in a working plane. The present invention also relates to a device and a method for straightening a curved worksheet and a device for handling such a worksheet.
2. Description of the Prior Art
A bending press which includes a device for handling sheet metal including gripper means for gripping an elongated piece of sheet metal and inserting the piece between the punch and the matrix along a loading plane substantially perpendicular to the working plane is known from Italian Patent Application No. 67224-A/88.
The press brake system according to the present invention is intended specifically for bending elongated pieces of sheet metal and in particular rectangular pieces which have one side much longer than the other (of the order of 1:10).
FIG. 2 of the appended drawings show in continuous outline a possible shape of a piece of sheet metal W which is to be bent or handled by a press brake system or a worksheet handling device according to the present invention. Due to technological problems related to the cutting of pieces of sheet metal, the pieces generally have an undesirable curved shape shown in broken outline in FIG. 2, with a concave longitudinal edge 2 and a convex longitudinal edge 4. This defect has been exaggerated in FIG. 2 in order to make the drawing more readily understood; the maximum difference F between the theoretical profile and the actual profile is generally between 0.2-2 mm for pieces of sheet metal with a length L of approximately 4 m.
As a result of this curvature, when the longitudinal edges 2 and 4 of the piece of sheet metal W are bent there is a variation in the widths of the resulting flanges between the central region of the piece of sheet metal W and the regions near its edges.