Effect of the Number of Work-roll Surface Division on Prediction of Contact Length in Coupled Analysis of Roll and Strip Deformation during Sheet Rolling

Abstract

In order to perform accurate three-dimensional rolling analysis of sheet deformation, it is required to predict the contact length accurately in consideration of the surface waviness due to the flattening deformation of work roll surface. Flattening deformation analysis based on theory of elasticity and three-dimensional elastic FEM have been developed, and their accuracy in predicting flattening deformation and contact length are validated in this report. As the flattening deformation of the work roll surface changes sharply at the boundary of contact area, the contact length is expected to change according to the number of work roll surface division, especially in circumferential direction, for calculation. Then, the influences of the number of division on roll profile and contact length used for numerical analysis are investigated. The following results are obtained; 1) The differences between the results obtained by three-dimensional elastic FEM and formula for roll flattening of Nakajima and Matsumoto is not significant. 2) When the number of division of work roll surface is increased, the end point of contact region moves toward the downstream side, therefore, the contact length becomes longer and it is necessary to divide the work roll surface into enough much elements. 3) As long as enough much elements are used for the calculation, solutions, such as rolling pressure distribution or thickness distribution of rolled strip, obtained by three-dimensional analysis reveal little difference from those obtained using formula for roll flattening given by Hitchcock.