Twelve Trouble-shootings in sheet metal bending

Sheet metal processing only metal materials use for sheet bending, pressure riveting, welding and a series of treatment processes. The bending and forming process of the metal plate is operated by a bending machine, and there will be a certain rebound in the bending, and the bending angle of the metal is slightly larger than the required angle.

The following are the problems and solutions encountered in the bending process of sheet metal processing

Question: The axis on both sides is not centered after bending

Cause: Material rebound will change the bending angle to cause the center line to shift
Solution: 1. Increase the calibration process 2. Improve the bending mode structure and reduce material rebound

Question: The curved edge is not straight and the size is unstable

Causes: 1. No line pressure or pre-bending warning was arranged during the design process
2. Insufficient material pressure
3. The circular wear of convex and concave molds is asymmetrical or the bending force is uneven
4. The height is too small
Solution:1. Design pressing line or pre-bending process
2. Increase pressure
3. Uniform gap between convex and concave molds, rounded and polished

4.The height size cannot be less than the minimum limit size

Question: There are scratches on the outer surface of the sheet metal plate after bending

Causes: 1. The surface of the finished material is not smooth
2. The bending radius of the punch is too small

3.The bending gap is too small

Solution:1. Improve the smoothness of convex and concave molds 2 Increase the bending radius 3 Adjust the bending gap

Question: The bending line is not parallel to the center of the two holes

Cause: When the bending height is less than the minimum bending limit height, external expansion occurs in the bending part

Solution: 1. Increase the height of the curved part 2. Improve the bending process

Question: Cracks in the bending corner

Causes: 1. The inner radius of the bend is too small

2. The grain direction of the material is parallel to the bending line
3. The burrs of the sheet face outwards
4. Poor metal plasticity

Solution: 1. Increase the bending radius of the punch

2. Change the blanking layout
3. The burrs become rounded corners in the piece
4. Anneal or use soft materials

Question: Extrusion and thinning of curved surfaces

Causes: 1. The fillet is too small. 2 The gap between the punch and the die is too small

Solution: 1. Increase the fillet radius 2. Correct the gap between the punch and the die

Question: Deformation of the hole due to bending

Cause: When using elastic bending and positioning holes, the outer side of the bending arm is pulled due to the friction between the surface of the die and the outer surface of the workpiece, causing the positioning hole to deform.

Question: The end surface of the workpiece is convex or uneven

Cause: When the outer surface of the material is bent, the outer surface of the material shrinks and deforms in the circumferential direction, and the inner surface is compressed in the circumferential direction to produce elongation deformation, so that the curved end surface causes a convex appearance in the bending direction .

Solution:1. In the final stage of stamping, the workpiece should have enough pressure.

2. Make the concave corner radius correspond to the rounded corner of the part
3. Process flow improvement

Question: The bottom of the concave part is not flat

Cause: 1. The material itself

2. The contact area between the top plate and the material is small or the ejecting force is insufficient.
3. No top device

Solution: 1. Leveling materials

2. Adjust the top material device to increase the top material force
3. Add ordering device or correction
4. Plus the shaping process

Question: The part with notch is bent downward

Cause: The two straight sides open to the left and right and deflect the bottom of the workpiece

Solution: 1. Improve the structure

2. Increase the process retention force at the incision, connect the incision, and cut the process after bending.

Question: The dimensional accuracy of the hole cannot be guaranteed after bending

Causes: 1. The expanded size is incorrect.

2. Caused by material rebound
3. Unstable positioning

Solution: 1. Calculate the blank size accurately

2. Increase the calibration process or improve the bending mold forming structure
3. Change the processing method or increase the process positioning

Question: Deformation in the width direction after bending

Cause: Torsion and deflection caused by inconsistent stretching and shrinking in the width direction of the part

Solution: 1. Increase bending pressure

2. Increase the calibration process
3. Ensure that the grain direction of the material and the bending direction have a certain angle