Bending, Bending Methods and Bending dies:

Bending and bending dies:

Bending is the metal working process by which a straight length is transformed into a curved length. It is very common forming process, for changing sheet and plate into channels, drums and tanks etc.

During the bending operation, the outer surface of the material is in tension and the inside surface is in compression. The strain in the bent material increases with decreasing the radius of curvature. The stretching of the bend causes the neutral axis to move toward the inner surface. In most cases, the distance of the neutral axis from the inside of the bend is 0.3 t to 0.5 t , where “t” is thickness of the part.

Bending terminology is illustrated in figure.

 

Bending Methods:

The two bending methods commonly used are v-bending and edge bending.

 

V- Bending:

In v-bending , a wedge shaped punch forces the metal sheet or strip into a wedge shaped die cavity, shown in fig.

The bend angle may be acute 90°, or obtuse. As the punch descends , the contact forces at the die corner produce a sufficiently large bending moment at the punch corner to cause the necessary deformation. To maintain the deformation to be plane strain , the side creep of the part during its bending is prevented or reduced by incorporating a spring loaded knurled pin in the die.

2: Edge Bending:

In edge bending , a flat punch forces the stock against the vertical force of the die. The bend axis is parallel to the edge of the die and the stock, is subjected.