Sheet metal bending method
Press brake is a machine of folding and bending flat panels. It follows the cutting process in the entire processing chain. The workpiece is placed on a die with a V-shaped opening. The wedge cutter (upper knife) presses the workpiece into the V-shaped opening and in this way bends the sheet to the required angle.
Most of the bending parts are made by techniques and methods such as suspended bending, in-mold bending, edge folding and pressing. The working methods all follow the same principle: the punch presses the workpiece into the lower die of the cavity. Therefore, the bending machine that performs the above-mentioned processes and methods is called a press brake.
Hanging bending
When punch presses the workpiece into the die, but does not press it against the die wall. During the downward movement of the punch, the edge of the workpiece bends upward and forms an angle.
The deeper the punch presses the workpiece into the die, the smaller the angle. At this time, there is a gap between the punch and the die. Overhang bending is also called path-dependent process.
Each angle requires a specific path. The press brake control system calculates the path and the corresponding pressing force at the same time. The path and pressing force depend on the characteristics of the mold, material and product (angle, length).
Bending in the mold
The punch completely presses the workpiece into the die, so there is no gap between the die, the workpiece and the punch.
This process is called clamping. The punch and the die must fit each other accurately. Therefore, each angle and shape requires a corresponding mold assembly. Once the workpiece is completely pressed in, the punch cannot continue to move downward.
The press brake control system continues to increase the punching force until it reaches the specified value. The pressure applied to the workpiece rises as a result, showing the contours of the punch and die. The angle is gradually stabilized under high pressure, and the rebound problem is almost completely eliminated.
Bending the flap
The built-in bending swing arm of the machine is composed of C-shaped profile, on which the lower and upper bending dies are installed.
When bending, the C-shaped profile moves up or down, or performs a small-scale elliptical movement, that is, flips. The swing arm bending machine runs semi-automatically, and is known for its speed and flexibility.
Even small batch production can be completed well. In addition, through the flap bending technology, the same mold can be used to achieve efficient bending of multiple radius sizes on a single part.
Folding and pressing
The edge of the sheet is usually completely bent (for example, the edge of the box), and then the edges are parallel to each other.
The finished part is therefore more stable as a whole or forms edge protection. Other parts usually need to be hung in the hemming. Folding and pressing are completed in two steps: First, the operator pre-folds the included angle of 30°, and then reinserts the workpiece and presses the included angle.
If there is a gap between the edges, it is called a hemming. The flanges are completely squeezed into each other during pressing. Hemming is path-dependent, but pressing is force-dependent.
