Problems and solutions for sheet metal bending process
- Dec 27, 2018 -

Bending, as a part of the sheet metal process, is often a neglected link. Many factories can't pick up any problems with the bending steps. They feel that they can meet the 90-degree bend. It can be compensated by a few degrees and a few degrees. However, I don’t know because of this "satisfaction". The bending process has great potential to be tapped.


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During the bending process, the outer layer is subjected to tension, and the inner layer is subjected to pressure. From the tension to the pressure, there is a transition intermediate layer which is neither untensioned nor stressed. The length of the middle layer during the bending process remains the same as before bending. The middle layer of So is the basic standard for calculating the unfolding length of a curved piece. The position of the middle layer is related to the degree of deformation. When the bending radius is large and the bending angle is small, the degree of deformation is small, and the middle layer is located near the center of the thickness of the sheet. When the bending radius becomes smaller and the bending angle increases, the degree of deformation increases, and the middle layer position gradually moves toward the inner side of the bending center.


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The following is a list of the problems encountered in the bending process in five sheet metal processing and solutions.


1. The bending edge is not straight and the size is unstable. The design process does not arrange the pressing line or pre-bending. The material is not enough. The unevenness of the convex and concave molds is asymmetrical or the bending force is uneven. The height is too small. Solution: Arrange the design of the press line or pre-bending process. Increase the pressing force. The convex and concave molds have uniform gaps and rounded corners. Height size cannot be less than the minimum limit size.


2. The cause of the external surface scratch after the workpiece is bent: the surface of the raw material is not smooth. The bending radius of the punch is too small. The bending gap is too small. Solution: Improve the finish of the convex and concave mold. Increase the bending radius of the punch. Adjust the bending gap.


3. Reasons for cracks in the bending angle: The inner radius of the bend is too small. The material grain direction is parallel to the bending line. The burrs of the blank are outward. Metal plasticity is poor. Solution: Increase the bending radius of the punch. Change the blanking layout. The burr is changed to the fillet in the workpiece. Annealed or using a soft material.


4 The reason why the bending causes the deformation of the hole: When the elastic bending is performed and the hole is positioned, the outer side of the bending arm is pulled due to the friction of the surface of the concave mold and the outer surface of the workpiece, so that the positioning hole is deformed. Solution: Use shape bending. Increase the pressure of the top plate. A plaque is added to the top plate to increase the friction to prevent the part from slipping during bending.


5 The reason for the thinning of the curved surface extrusion material is that the die radius is too small. The gap between the convex and concave molds is too small. Solution: Increase the radius of the die corner. Correct the convex and concave mold gap.