Estimation of Deformation Length in Cold Roll Forming Considering the Effect of Work Hardening

Cold roll forming is a process for manufacturing of long sheet metal products with constant cross sections. This process occurs gradually in several forming stations. The distance between two stations is highly influenced by the deformation length. Deformation length is the length influenced by the plastic strain initiated at the roll-sheet contact. In this study, a relation for estimation of deformation length has been derived by extension of Bhattacharyya equation that could be used in different stages of roll forming. The material work hardening exponent, sheet thickness, bend angle, flange length and radius of curvature are the parameters considered in this relation. The distance between two stations is estimated according to the deformation length before the second station and the length under the influence of the spring back after the first station. By considering the effect of spring back and deformation length, a methodology has been provided for optimization of distance between stations in roll forming. A finite element model was developed for evaluation of the derived relation. It was concluded that the minimum distance between stations decreases when work hardening exponent is increased.

Keywords:

Cold Roll Forming , Deformation Length , Spring Back , Work Hardening