Experimental and numerical investigation of cold roll forming process

Abstract

This research work is focused on the cold roll forming process to produce U-channel from the flat sheet. The mechanical properties of aluminum alloy was obtained from the tensile test and subsequently, the properties were incorporated into LS-DYNA to define the material plastic region. The forming process involves the progressive sheet deformation by passing it through a roll pass at constant roll speed. Each sets are designed at different bending angle to increase the deformation until the final geometry is achieved and here, the forming machine with four roll stands were used to manufacture the parts. As a sheet is going into different passes at the same time, the sheet plastic deformation is so complex and highly non-linear because of various stress and strain developments. From experimental results, at low roll speed (RS) the longitudinal bow was observed in the formed parts and to investigate, numerical simulation was modeled at various roll speed and found that as roll speed increasing the longitudinal bow noticed to be decreasing. To confirm the finite element results, one more experiment at high speed was performed and the obtained results showed better agreement with the simulation results. Before confirming the accuracy, many issues were encountered and modified such as mesh size at roller and blank, contact mechanism, choosing element formulation and friction coefficient. Furthermore, the adaptive meshing procedure was adopted to efficiently remesh the sheet at contact locations. The research procedures presented can be utilized to perform the forming process for any existed or new material to form a desired shape for a specific applications in the automobile and aerospace industries.