It is not easy to bend a thick steel plate to a narrow radius. There are many variables to consider, such as thickness, surface and edge conditions, and the chemical composition of the material. Plate bending (also called plate rolling) is a process in which a force is applied to the plate, causing deformation along the bending axis, thereby forcing the plate to bend at the desired angle. At the moment of bending, the material is under tension, where the material expands on the curved outer surface and compresses or shrinks inside.
After the bending force is released, the residual stress in the material will cause the plate to rebound. To compensate for springback, the plate needs to be bent to a greater angle than required. Experienced operators can calculate the expected amount of rebound based on a variety of factors, which can help speed up material construction with fewer attempts.
Normally, the plate bending is performed on the pressure brake. The bending machine contains two tools: an upper tool (called a "punch") and a lower tool (called a "die"). The board to be bent must be placed on the die and held in place, while the punch is lowered onto the board and the force applied causes it to bend. The bending angle is controlled by the depth that the punch presses the plate into the die. The most common plate bending is called V-bending, in which the punch and die tools used are V-shaped.
When the punch does not push the material all the way to the bottom of the mold cavity, and there is space below it, we will perform "air bending". When the punch pushes the material all the way to the bottom of the mold cavity, we have the "bottom line ". The bottoming process can better control the bending angle to reduce springback. It should also be remembered that when the bending machine bends, the thicker and harder the plate, the greater the minimum bending radius.
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