Problem 1: The bending edge is not straight and the size is unstable
reason:
1. The design process does not arrange pressing or pre bending
2. Insufficient material pressing force
3. Asymmetrical wear of round corners of male and female dies or uneven bending force
4. The height is too small
terms of settlement:
1. Design line pressing or pre bending process
2. Increase the pressing force
3. The clearance between male and female dies is even, and the fillets are polished
4. The height dimension cannot be less than the minimum limit dimension
Problem 2: The outer surface of the workpiece is scratched after bending
reason:
1. Raw material surface is not smooth
2. The bending radius of punch is too small
3. The bending clearance is too small
terms of settlement:
1. Improve the smoothness of punch and die
2. Increase the bending radius of punch
3. Adjust bending clearance
Problem 3: There are cracks in the bending angle
reason:
1. The inner radius of bending is too small
2. Material grain direction is parallel to bending curve
3. The burr side of the blank is outward
4. Poor plasticity of metal
terms of settlement:
1. Increase the bending radius of punch
2. Change blanking layout
3. The burr shall be changed to the internal fillet of the workpiece
4. Annealed or made of soft material
Problem 4: Hole deformation caused by bending
reason:
When bending by elastic pressure and positioning by holes, the outer side of the bending arm is pulled due to friction between the surface of the die and the outer surface of the workpiece, which makes the positioning hole deformed.
terms of settlement:
1. Adopt shape bending
2. Increase the pressure of ejector plate
3. Add pitting grid on the ejector plate to increase friction and prevent the parts from slipping during bending
Problem 5: The extruded material on the curved surface becomes thinner
reason:
1. Die fillet too small
2. Too small clearance between punch and die
terms of settlement:
1. Increase the fillet radius of the die
2. Correction of punch and die clearance
Problem 6: The end face of the part bulges or is uneven
reason:
1. When bending, the outer surface of the material is pulled in the circumferential direction to produce shrinkage deformation, and the inner surface is pressed in the circumferential direction to produce elongation deformation, so the end face of the material is flexed along the bending direction to produce bulge.
terms of settlement:
1. The punch and die of parts shall have enough pressure at the last stage of stamping
2. Make the fillet radius of the die corresponding to the fillet of the part
3. Add procedures to improve
Problem 7: The bottom of concave part is uneven
reason:
1. The material itself is uneven
2. Small contact area between top plate and material or insufficient jacking force
3. No ejector in the die
terms of settlement:
1. Leveling material
2. Adjust the jacking device to increase the jacking force
3. Add jacking device or correct
4. Adding and shaping process
Problem 8: The axis centers of the two opposite holes on both sides are shifted after bending
reason:
Material springback changes the bending angle to make the centerline shift
terms of settlement:
1. Add correction procedure
2. Improving the Structure of Bending Die to Reduce Material Rebound
Problem 9: The accuracy of hole position and size cannot be guaranteed after bending
reason:
1. Unfolding size of parts is incorrect
2. Caused by material rebound
3. Unstable positioning
terms of settlement:
1. Accurately calculate the blank size
2. Add correction process or improve bending die forming structure
3. Change process processing method or add process positioning
Problem 10: The bending curve is not parallel to the center line of the two holes
reason:
Torsion and deflection due to inconsistent drawing and shrinkage in the width direction of the workpiece
terms of settlement:
1. Increase bending pressure
2. Add correction procedure
3. Ensure that there is a certain angle between the material grain direction and the bending direction
Problem 11: After bending, the width direction is deformed, and the bent part has bow deflection in the width direction
reason:
Torsion and deflection due to inconsistent drawing and shrinkage in the width direction of the workpiece
terms of settlement:
1. Increase bending pressure
2. Add correction procedure
3. Ensure that there is a certain angle between the material grain direction and the bending direction
Question 12: The part with notch flexes downward
reason:
The notch makes the two straight edges open to the left and right, causing deflection at the bottom of the part
terms of settlement:
1. Improve product structure
2. Increase the process allowance at the notch to connect the notches, and then cut off the process allowance after bending
