Investigation into the numerical model behaviour of Belleville washers in cold roll forming

With the steady increase in demand for roll formed products, due to their application in fields such as automotive, construction, architecture, etc., roll forming companies are challenged with rising customer demands. Companies are struggling to bring a product through from design to manufacture at improved rates, whilst achieving tighter tolerances. The roll forming process may also induce undesirable forming defects such as twist, distortion and straightness problems. Over the years, numerical simulations have been deployed to assist with the geometric validation of these effects. For the purpose of this paper, an investigation shall focus on an individual parameter within the finite element analysis of the cold roll forming process, i.e. the ’unknown’ spring effect acting of the top roll during the forming process due to the implementation of Belleville washers in the pillar set up. This parameter is assessed over a range of applied loads and compared with a standard friction model with fixed top and bottom rolls. The longitudinal strains on the final profile, the geometric accuracy and thickness variation are observed and presented in this paper. Reasoning is also provided to explain why the final profile bows in the vertical direction.