12 Solutions for Sheet Metal Bending Problems

Bending and forming of the metal sheet are carried out on plate bending machine. Put the workpiece on plate bending machine, use lifting lever lift brake block, then make the workpiece slide to a proper position, and then down the brake block to the workpieces, and further press on the bending lever to realize the bending of the metal sheet.

Minimum bending radius is a function of the ductility and thickness of the metal formed.

For aluminum sheet metal, the bending radius is greater than the thickness of the plate.

Due to the elasticity, the bending angle of metal is slightly bigger than angle required.

The bending of the metal sheet is conducted in metal processing workshop.

Metal sheet processing is only a series of processing techniques for bending, riveting and welding of metal materials.

The problems occurred in this process and the corresponding solutions are discussed below.

Problem 1: The bending edge is not straight and the size is unstable.

Reasons

  1. no line pressing or pre-bending.
  2. inadequate material pressure
  3. dissymmetric convex-concave die fillet and uneven bending pressure
  4. low height

Solutions

  1. design line pressing or pre-bending techniques
  2. increase jacking force
  3. even clearance in the convex-concave die and polish fillet
  4. make the height larger or equal to the minimum size

 

Problem 2: The workpiece is scraped after bending.

Reasons

  1. unsmooth material surface
  2. too small convex die bending radius
  3. too small bending clearance

Solutions

  1. improve the smoothness of concave die
  2. increase convex die bending radius
  3. adjust bending clearance

 

Problem 3: There are cracks at bending angles.

Reasons

  1. too small bending radius
  2. material grain parallel to the bending line
  3. burr of workblank extending outward
  4. poor remoldability of metal

Solutions

  1. increase bending radius of convex die
  2. change blanking layout
  3. making burrs at workpiece’s inner fillet
  4. annealing or using soft material

 

Problem 4: Bending causes hole deformation

Reasons

When the elastic bending is used to positioning the hole, the outside of the bending arm is pulled by friction on the surface of the concave mold and the outer surface of the workpiece, making the positioning hole deformed.

Solutions

  1. employing shape bending
  2. increase coverboard pressure
  3. add pitting plaid to coverboard to increase friction so as to prevent workpiece from sliding when bending

 

Problem 5: The bending surface is thinner.

Reasons

  1. too small convex-concave die fillet
  2. too small convex-concave die clearance

Solutions

  1. increase the radius of convex-concave die fillet
  2. adjust the convex-concave die clearance

 

Problem 6: The workpiece surface is bulging or uneven.

Reasons

Under the tension in the circumferential direction, the outer surface of the material shrinks while the inner surface extends during bending, and forming bulging in the bending direction.

Solutions

  1. provide adequate pressure to convex-concave die at the final stamping stage
  2. make concave round angle radius equal to that of the workpiece’s excircle
  3. optimize techniques

 

Problem 7: The concave part is uneven at the bottom.

Reasons

  1. uneven material
  2. small contact area between coverboard and material or inadequate jacking force
  3. no material support device in concave die

Solutions

  1. leveling materials
  2. adjust material support device and increase jacking force
  3. increase or correct material support device
  4. increase the shaping processes

 

Problem 8: The axis of holes on two sides are misaligned after bending.

Reasons

The material rebound changes the bending angle, making the central line misaligned.

Solutions

  1. increase correction process
  2. improve bending model structure to reduce material rebound

 

Problem 9: The precise hole position cannot be guaranteed after bending.

Reasons

  1. incorrect unfolding sizes
  2. material springback
  3. unstable positioning

Solutions

  1. calculate the workblank size accurately
  2. increase correction process or improve bending die structure
  3. change processing methods or improve positioning

 

Problem 10: The bending line is not parallel to the two-hole center.

Reasons

When the bending height is less than the minimum bending height, the bending part occurs expansion.

Solutions

  1. increase the height of workpiece to be bent
  2. improve bending techniques

 

Problem 11: deformation occurs in terms of width after bending (the bending part occurs bow deflection in width).

Reasons

The inconsistent depth and shrinkage in the width of workpiece cause torsion and deflection.

Solutions

  1. increase bending pressure
  2. increase correction process
  3. ensure a certain angle between materials and bending direction

 

Problem 12: workpiece with incision occur downward deflection.

Reasons

The incision makes the two straight edges open to the left and right side, forming deflection at the bottom.

Solutions

  1. improve the workpiece structure
  2. increase processing allowance at incisions to connect incisions and then cut off the process after bending
2018-04-12T17:51:36+00:00 Bending|

2 Comments

  1. Emily April 12, 2018 at 2:03 pm - Reply

    In the first passage, you write “brake black” in the third line. Maybe it is a small error.

    • MachineMfg April 12, 2018 at 5:52 pm - Reply

      thanks, it has been revised.

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