Practical design equations for cold roll forming of doubly curved hull plates using line array roll set

Abstract

The line array roll set (LARS) process, as one of many kinds of incremental forming processes, is a continuous process in which a flat metal plate is formed into a singly or doubly curved plate through successive passes of forming rolls. It was found that the curvature level of the formed plates in the previous study was well over the curvature required in shipyards. This fact shows that the LARS method has good potential for shipbuilding applications. A ship hull is composed of many curved plates with various double curvatures. Consequently, for the desired curvatures of target shapes, the bending radii must be determined considering the springback phenomenon. In the present study, design equations are proposed for engineering applications, particularly in relation to shipbuilding. For the development of design equations, the deformation of the plates is analyzed using some engineering assumptions. In addition, experimental coefficients are introduced to simplify the theoretical equations. The experimental coefficients are determined as the best fit for the experimental data using the least squares method, resulting in the derivation of design equations. It has been shown that the prediction from the design equation with the results from the experiments shows good agreement and can be used for practical applications.