Application of 2-dimensional FEM to predict the thickness profile in 4-high mills

In order to investigate the strip crown and edge drop effects in cold and hot mills with special crown rolls (SCR) under a specific roll force a 2-dimensional finite element model was developed. Using a technique of inversion of condensed stiffness matrix formed by eliminating all the nodes except those where contact is likely to take place, the contact pressure between work roll and backup roll can be effectively obtained. This model is somewhat faster than a 3d FE model, but slower than the slit model derived from the simple beam theory. However, the 2d FE model can deal with any roll geometry and include the profile control means of roll bending and shift. Besides, with this model, it is easy to consider the influence of strip divergence, transverse friction force and work roll contact on the strip profile/crown. Numerical simulations have shown the effect.