Bending is a process of folding and bending flat sheets, closely following the cutting process in the entire manufacturing chain. The workpiece is placed on a die with a V-shaped opening. Wedge-shaped tools (punches) press the workpiece into the V-shaped opening and bend the sheet to the desired angle.
Most bending processes involve air bending, where the bending, folding, and pressing of the edges are achieved through techniques and methods. The operational mode follows the same principle: repressing the workpiece into the lower die of the die set. Therefore, a bending machine that implements the mentioned techniques and methods is called a press brake.
1. Air Bending
The punch presses the workpiece into the die but does not reach the die walls. As the punch moves downward, the workpiece bends upward, forming an angle. The greater the depth to which the punch presses the workpiece into the die, the smaller the angle. There is a gap between the punch and the die in this case. Air bending is also known as a path-dependent process. Each angle requires a specific path. The machine control system simultaneously calculates the path and the corresponding punching force. The path and punching force depend on the die, material, and product characteristics (angle, length).
2. Bottoming Bending
The punch fully presses the workpiece into the die, leaving no gap between the die, workpiece, and punch. This process is called bottoming. The punch and die must match each other accurately. Therefore, each angle and shape require corresponding die components. Once the workpiece is fully pressed, the punch can no longer move downward. The machine control system continues to increase the punching force until the specified value is reached. The increasing pressure applied to the workpiece reveals the contour of the punch and die. The angle gradually stabilizes under high pressure, almost eliminating the issue of springback.
3. Folding Bending
The bending arm, composed of C-shaped profiles, is built into the machine tool, with the lower and upper bending dies mounted on the upper part. During bending, the C-shaped profiles move upward or downward or undergo small elliptical motions, i.e., flipping. Folding bending machines are known for their semi-automatic operation, which is fast and flexible, even for small batch production. Additionally, by utilizing the flipping bending technique, efficient bending with various radius sizes can be achieved on a single part using the same set of dies.
4. Edge Folding and Hemming
The edges of the sheet are typically fully bent (like the edges of a box) and then folded parallel to each other. This provides overall stability to the finished component or forms edge protection. Other components often need to be hung on the folded edges. Folding and hemming are divided into two steps: first, the operator pre-folds a 30° angle, and then the workpiece is reinserted and pressed into the angle. If there is a gap between the edges, it is called a folding edge. The bent edges are fully squeezed together. Folding edges are path-dependent, while hemming edges are strength-dependent.
Most bending processes involve air bending, where the bending, folding, and pressing of the edges are achieved through techniques and methods. The operational mode follows the same principle: repressing the workpiece into the lower die of the die set. Therefore, a bending machine that implements the mentioned techniques and methods is called a press brake.
1. Air Bending
The punch presses the workpiece into the die but does not reach the die walls. As the punch moves downward, the workpiece bends upward, forming an angle. The greater the depth to which the punch presses the workpiece into the die, the smaller the angle. There is a gap between the punch and the die in this case. Air bending is also known as a path-dependent process. Each angle requires a specific path. The machine control system simultaneously calculates the path and the corresponding punching force. The path and punching force depend on the die, material, and product characteristics (angle, length).
2. Bottoming Bending
The punch fully presses the workpiece into the die, leaving no gap between the die, workpiece, and punch. This process is called bottoming. The punch and die must match each other accurately. Therefore, each angle and shape require corresponding die components. Once the workpiece is fully pressed, the punch can no longer move downward. The machine control system continues to increase the punching force until the specified value is reached. The increasing pressure applied to the workpiece reveals the contour of the punch and die. The angle gradually stabilizes under high pressure, almost eliminating the issue of springback.
3. Folding Bending
The bending arm, composed of C-shaped profiles, is built into the machine tool, with the lower and upper bending dies mounted on the upper part. During bending, the C-shaped profiles move upward or downward or undergo small elliptical motions, i.e., flipping. Folding bending machines are known for their semi-automatic operation, which is fast and flexible, even for small batch production. Additionally, by utilizing the flipping bending technique, efficient bending with various radius sizes can be achieved on a single part using the same set of dies.
4. Edge Folding and Hemming
The edges of the sheet are typically fully bent (like the edges of a box) and then folded parallel to each other. This provides overall stability to the finished component or forms edge protection. Other components often need to be hung on the folded edges. Folding and hemming are divided into two steps: first, the operator pre-folds a 30° angle, and then the workpiece is reinserted and pressed into the angle. If there is a gap between the edges, it is called a folding edge. The bent edges are fully squeezed together. Folding edges are path-dependent, while hemming edges are strength-dependent.
