The role of straightening mechanism in Cold Roll Forming Line

Cold bending forming refers to the bending of a strip along a straight line (cold bending forming mold) in the longitudinal direction. The pressure generated during the bending deformation process is combined with the residual stress present in the strip, often causing the strip to deviate from the center of the cold bending forming roller. The most commonly used words to describe the degree of deviation of the strip after it comes out of the last forming roll are: side bending – horizontal bending, warping – vertical bending, twisting – spiral shape. To solve this problem, a straightening mechanism should be used at the end of the cold bending machine.

The basic principle of a straightening mechanism is to apply sufficient pressure in the opposite direction through the straightening mechanism to produce permanent deformation on profiles with defects such as side bending and warping. If the deformation in the opposite direction is appropriate, then after rebounding, the profile can be completely straightened. If the formed profile undergoes twisting deformation in a certain direction, the straightening mechanism rotates the profile in the opposite direction, resulting in permanent plastic deformation. If the rotation angle is appropriate, the profile will no longer twist after rebounding.

The straightening of bending or twisting is usually carried out between the last forming roller and the cutting die. If the last rolling roller cannot effectively support the profile, the entire profile section must be supported when entering the straightening mechanism on one side. Straightening asymmetric profiles involves the possibility of torsional deformation while straightening, which requires simultaneous bending and torsional straightening in the opposite direction of profile deformation. During the straightening process, the profile will move up, down, left, and right, requiring a relatively loose gap between the straightening mechanism and the profile. There can be a certain gap between the straightening mechanism and the surface of the profile.