Deformation of metal roof sheet with Cold Roll Forming Process

ibr sheet roll forming machine acts as the main production for steel roof, has become a necessary in roof system construction. With 20 years experience in roll forming machine industry, our engineers have found the following deformation of metal roof sheet.
The deformations are as follows:

1 Pocket-wave generation: The plate produces transverse tensile and transverse strains during bending. The sheet thickness along the thickness direction is relatively small. According to the Poisson relationship of the material deformation. Inevitably, there will be shrinkage in the longitudinal direction at sites where deformation is concentrated. Under the influence of force, bag-like bulges appear in the instability. This is what we often call bag-shaped waves.

2 side waves. Edge waves are a more common defect than bag-shaped waves. Its production is mainly a combination of two effects: the first is the same as the previous bag-shaped wave. This is because the material in the curved section of the section is subjected to transverse tensile stress, resulting in a transverse tensile strain. In the case where the strain in the direction of thickness is not large, longitudinal shrinkage occurs according to the Poisson relation, and the edges of the edge are subjected to compressive stress to generate edge waves; the second is that the material of the edge part is stretched under the action of external force. lengthen. Then it is compressed and sheared again to cause plastic deformation, causing edge waves. These two effects superimpose on each other. Edge waves formed.

3 longitudinal bending. Cause more longitudinal bending. One of the important reasons is that the edge of the section is subjected to a tensioning force when it is bent on the side. Trying to lengthen the entire section in the longitudinal direction. But the tension is not enough to stretch the entire rigid section. Causes the top of the rolling stock to bend upward or downward.