12 major problems in sheet metal bending forming of metal parts


Metal plates are used in the processing of metal parts. The bending and forming of the metal plates are carried out on the bending machine. The workpiece to be formed is placed on the bending machine, and the brake shoe is lifted by the lifting lever, and the workpiece slides to Then lower the brake shoe onto the workpiece to be formed at the appropriate position, and realize the bending and forming of the metal by applying force to the bending lever on the 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 larger than the thickness of the plate. When bending, due to a certain degree of spring back, the bending angle of the metal is slightly larger than the required angle. The bending of sheet metal is carried out in the metal processing workshop.
Sheet metal processing is just a series of processes such as bending, riveting, and welding of metal materials. The following focuses on the problems and solutions encountered in the bending process in sheet metal processing.

Product Case 4

 

1.The bending edge is not straight and the size is unstable
Reasons:
(1)The design process did not arrange crimping or pre-bending
(2)The material pressing force is not enough
(3)The rounded corners of the convex and concave molds wear asymmetrically or the bending force is uneven
(4)The height dimension is too small
Solutions:
(1)Design line pressing or pre-bending process
(2)Increase the pressing force
(3)Uniform gap between convex and concave molds, rounded corners polished
(4)The height size cannot be less than the minimum limit size

2.The outer surface of the workpiece is scratched after bending
Reasons:
(1)The surface of the raw material is not smooth
(2)The bending radius of the punch is too small
(3)The bending gap is too small
Solutions:
(1)Improve the finish of convex and concave molds
(2)Increase the bending radius of the punch
(3)Adjust the bending gap

3.Cracks in the bending corner
Reasons:
(1)The inner radius of the bend is too small
(2)The material pattern is parallel to the bending line
(3)The burr of the blank faces outwards
(4)Poor metal plasticity
Solutions:
(1)Increase the bending radius of the punch
(2)Change the blanking layout
(3)The burr is changed to the fillet in the part
(4)Anneal or use soft materials

4. Deformation of the hole caused by bending
Reason: When using elastic bending and positioning with a hole, 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, which deforms the positioning hole.
Solutions:
(1)Use shape bending
(2) Increase the pressure of the top plate
(3)Add a pitting grid pattern on the top plate to increase the friction and prevent the part from slipping when bending

5.thinning of the extrusion material on the curved surface
Reasons:
(1)The fillet of the die is too small
(2)The gap between the convex and concave molds is too small
Solutions:
(1)Increase the corner radius of the die
(2)Correct the gap between convex and concave molds

6.The end of the part is bulged or uneven
Reason: When bending, the outer surface of the material is stretched in the circumferential direction to produce shrinkage deformation, and the inner surface is compressed in the circumferential direction to produce elongation and deformation, so the swelling phenomenon of the flexural end surface appears along the bending direction.
Solutions:
(1)The convex and concave dies should have enough pressure in the final stage of stamping.
(2)Make the die fillet radius corresponding to the outer fillet of the part
(3)Increase process improvement

7.The bottom of the concave part is not flat
Reasons:
(1)The material itself is not flat
(2)The contact area between the top plate and the material is small or the ejecting force is not enough
(3)No ejector device in the cavity
Solutions:
(1)Leveling materials
(2)Adjust the ejecting device to increase the ejecting force
(3)Add ejector device or correction
(4)Add shaping process

8.The axis of the two holes facing each other is misplaced after bending
Reason: Material spring back changes the bending angle to make the centerline shift
Solutions:
(1)Increase the calibration process
(2)Improve the structure of the bending die to reduce material rebound

9.The dimensional accuracy of the hole position cannot be guaranteed after bending.
Reasons:
(1)The unfolded size of the part is incorrect
(2)Caused by a material rebound
(3)Unstable positioning
Solutions:
(1)Calculate the blank size accurately
(2)Increase the correction process or improve the bending mold forming structure
(3)Change process method or increase process positioning

10.The bending line is not parallel to the centerline of the two holes
Reason: when the bending height is less than the minimum bending limit height, the bending part will expand outwardly
Solutions:
(1)Increase the height of the bending parts
(2)Improve the process method of bending parts

11.Deformation in the width direction after bending, and bow deflection in the width direction of the best part
Reason: due to the inconsistent drawing and shrinkage in the width direction of the workpiece, torsion and deflection are generated
Solution:
(1) Increase bending pressure
(2)Increase the calibration process
(3)Ensure that the material grain and bending direction have a certain angle

12. the part with notch flexes downwards
Reason: The incision makes the two straight sides open to the left and right, and the bottom of the workpiece is deflection
Solution:
(1)Improve the part structure
(2)Increase the process allowance at the incision to connect the incisions, and then cut the process allowance after bending

 

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