Study on the continuous roll forming process of swept surface sheet metal part

Continuous roll forming (CRF) is an effective process to manufacture swept surface parts of sheet metal. The forming tool in CRF is a pair of small-diameter bendable forming rolls, a swept surface is formed continuously after the rotating rolls sweep out the whole sheet metal blank. The two bent rolls and the non-uniformly distributed roll gap along the rolls' length make the sheet metal bent in longitudinal and transverse directions simultaneously, the cross-section curve of the formed swept surface is controlled by the curved profile of the forming rolls and the spine curve is controlled by the differential elongations of sheet metal generated by roll gap. In this paper, a necessary condition for the formation of a swept surface is proposed and analyzed, the parametric equations of the formed surface in CRF are derived and the method to determine the roll gap for forming a given swept surface is presented. The numerical simulations and analyses on the CRF processes demonstrate the validity of the presented theoretical models. The experimental and measured results show that the formed surfaces are in good agreement with the desired surfaces, and swept surface parts with good forming precision can be obtained by CRF process.