Roll forming is a manufacturing process that involves plastic forming via bending using a rolling motion. During roll forming, a coil or blank is formed incrementally in a stepless and continuous process with the aid of rolls to fabricate profile rails. The shape of the rolls predicted the incremental deformation in the cross-sections of the U-profile rails. However, the final shape after the roll-forming process is entirely different from the modeled parts because of the springback caused by the mechanical properties of the materials. The design of roll-forming processes has been investigated to address typical plastic defects, such as springback and residual stress. Roll flower diagrams were developed in the initial stage of the design of the roll-forming processes. These diagrams show the cross-sectional shapes of the product at various stages of the process, superimposed on each other. The diagrams contain information for the process design, including the incremental deformation, number of passes, and setup angle of the rolls. There is no standard method for designing roll–flower diagrams. These were developed based on the designer’s experience with the material properties and multiple shapes. In this study, roll flower diagrams were designed using the developed formula, considering constant radius-of-curvature or length-of-curvature zones in the cross-sections of U-profile rails. Roll-forming processes were simulated using the commercial FEM code Abaqus to measure the loads of the rolls, springback of the blank, and residual-stress history. Simulation and experimental results regarding the shapes of the U-profile rails were compared to validate the process design method.

During roll forming a sheet metal is continuously and progressively formed into a product of the required cross-section and longitudinal shape. An example product is a circular tube with a required diameter, wall-thickness and straightness. Roll forming occurs by passing the sheet through a series of forming rolls that are arranged in tandem. Each pair of forming rolls in the roll forming line plays a particular role in obtaining the required cross-section and longitudinal shape in the product.In recent years, that process is often applied to car body parts by automotive industries. In the current study, an optimal model design and proper roll-pass sequences as well as the number of forming rolls and bending angles were used to produce a sill side. The effects of the process parameters on the final shape formed by roll forming defects were evaluated.