Keep in mind that roll forming has three forming regions. The first region is the noncontact forming (air bending) region. The second region is the contact forming (tool bending) region that ends at the central line of the rolls. The third region is the springback region that begins as the section exits the central line of the rolls. The profile transition region comprises both the noncontact forming region and the contact forming region.
The stresses and moments are products of not only the forces exerted on the strip, but also the distances between the forming regions.
