A Roll-Stack Contact Mechanics Model to Predict Strip Profile in Rolling Mills With Asymmetric, Continuously Variable Crown Rolls

Introduced is an efficient new model to compute the roll-stack deflections and contact mechanics behaviors for metal rolling mills with asymmetric roll crowns. The new model expands the simplified mixed finite element (FE) method to consider complex antisymmetric contact conditions of continuously variable crown (CVC) roll diameter profiles designed for use with work-roll (WR) shifting on four-high mills, and intermediate-roll (IR) shifting on six-high mills. Conventional roll-stack deflection models are either more computationally expensive or exploit more simplifying assumptions. Moreover, almost all existing approaches fail to adequately simulate the antisymmetric CVC contact problem required for model-based control of thickness profile and flatness in hot and cold CVC rolling mills. The presented model efficiently captures bending, shear, and flattening deformations while computing contact interference forces, binary contact locations, and net effects of roll and strip crowns. Strip thickness profiles and contact force distributions predicted by the new model are checked against known theoretical solutions, and compared to predictions from large-scale FE simulations for a four-high mill with WR CVC shifting, and a thin-strip six-high mill with IR CVC shifting.