Common Problems and solutions of sheet metal bending forming
The bending and forming of the metal plate is carried out on the plate bending machine, the workpiece to be formed is placed on the plate bending machine, the brake shoes are lifted by the lifting lever, and the workpiece slides to the proper position, the brake shoe is then lowered to the workpiece to be formed, and the metal is formed by applying force to the bending lever on the plate bending machine. The minimum bending radius is a function of the ductility and thickness of the formed metal. For aluminum plates, the bending radius of the metal is greater than the thickness of the plate. When bending, the metal will bend at a slightly greater angle than required due to a certain springback. The bending of sheet metal is done in a metal working shop.
Sheet metal processing is the process of bending, pressing, riveting, welding and so on. The following for sheet metal processing bending process problems encountered and solutions.
Problem 1: The bending edge is not straight and the dimension is not stable
Reason:
1. There is no line pressing or pre-bending in the design process
2. Insufficient material pressure
3. The round corner wear of punch and die is not symmetrical or the bending force is not uniform
4. Too Small for height
The Solution:
1. design pressing line or pre-bending process
2. Increase pressure
3, Punch clearance uniform, round corner polishing
Height dimensions shall not be less than the minimum limit size
Problem 2: The external surface of the workpiece is abraded after bending
Reason:
1. Raw materials don't have a smooth surface
The bending radius of punch is too small
3. Too little bending clearance
The Solution:
1. Improve the smoothness of the punch and die
2. Increase the bending radius of the punch
3. Adjust the bending gap
Problem 3: There is a crack in the bend
Reason:
1. The inside radius of the bend is too small
2. The Grain Direction of the material is parallel to the bending line
3. The burr of the blank faces outwards
4. Poor metal plasticity
The Solution:
1. Increase the bending radius of the punch
2. Change the blanking layout
3. The burr should be rounded inside the workpiece
4. ANNEAL or use soft materials
Problem 4: Bending Causes Hole Deformation
Cause: The outer side of the bending arm is pulled by the friction between the surface of the die and the outer surface of the part when the hole is positioned by elastic pressing and bending.
The Solution:
1. Bend in shape
2. Increase the top plate pressure
3. Adding pockmarks on the ejector plate to increase the friction and prevent the parts from sliding when bending
Problem 5: Thin extruded material for curved surface
Reason:
1. Die Corners are too small
2, punch clearance is too small
The Solution:
1. Increase die fillet radius
2. Fix the gap between the Punch and die
Problem 6: The end surface of the product is bulging or uneven
Reason:
1. When the material is bent, the outer surface will contract in the circumferential direction, and the inner surface will stretch and deform in the circumferential direction.
The Solution:
1. The Punch and die shall have sufficient pressure at the last stage of stamping
2. Make the die fillet radius corresponding to the outside fillet of the part
3. ADD process improvements
Problem 7: The bottom of the concave part is uneven/nReason:/n1. The material itself is uneven/n2. The contact area between roof and material is small or the jacking force is insufficient/n3. No top material device in the die/nThe Solution:/n1. Leveling materials/n2. Adjust the ejecting device to increase the ejecting force/n3. Add a topping device or calibration/n4. Add plastic surgery/nProblem 8: The axis of the two opposite holes is staggered after bending/nCAUSE: material rebound changes the bending angle so that the center line offset/nThe Solution:/n1. Add calibration procedures/n2. Improve the structure of bending die to reduce the material rebound/nProblem Nine: After Bending can not guarantee the hole position size accuracy/nReason:/n1. The part is not unfolded to the correct size/nCaused by material rebound/n3. Location instability/nThe Solution:/n1. Calculate the blank size accurately/n2. Add calibration procedures or improve the bending die structure/n3. Change process method or increase process orientation/nProblem 10: The curved line is not parallel to the center of the two holes/nCAUSE: When the bending height is less than the minimum bending limit height, the external expansion appears at the bending part/nThe Solution:/n1. Increase the height of the bending part/n2. Improve the process of bending parts/nQuestion 11: After Bending, the width direction of deformation, the bending position in the width direction of the bow deflection/nCAUSE: As a result of parts width direction of the drawing and shrinkage inconsistent torsion and deflection/nThe Solution:/n1. Increase Bending pressure/n2. Add calibration procedures/n3. Make sure the material has a certain angle between the grain direction and the bending direction/nProblem 12: Downward deflection of parts with notches/nCAUSE: Incision so that the two straight side to the left and right to open, the bottom of the product deflection/nThe Solution:/n1. Improve the structure of the parts/n2. Increase the process allowance at the incision, connect the incision, and cut off the process allowance after bending/n