3D finite element model for roll stack deformation coupled with a Multi-Slab model for strip deformation for flat rolling simulation

International audienceRoll deformation is an extremely important problem in strip rolling, all the more as the strip is thinner. It results in profile defects (the strip thickness varies in the transverse direction) and flatness defects (the strip exits the rolling mill wavy). This becomes a more and more stringent issue for modern, harder steels such as Advanced High Strength Steels (AHSS). Numerous compensation techniques are used, alone or in combination: roll grinding crown, 4- or 6-Hi mills, cluster mills, with shiftable tapered rolls, CVC-shaped rolls (Continuously Variable Camber), pair-cross stands, etc. Elaborating the correction strategy for a specific strip rolling operation requires a model of the action of these profile and flatness actuators. A hybrid model was developed in which the roll stack deformation is modelled with a commercial Finite Element Method (FEM), coupled with a Multi-Slab model for strip deformation. This new model allows simulating virtually any type of rolling mill configuration at a reasonable cost (CVC, shiftable rolls, pair cross stands, cluster mills) including cases of incoming strip with defects (crown or wedge), by virtue of the FEM generality and versatility. The example taken here is a 6-high rolling mill with shiftable intermediate rolls (an anti-symmetric configuration). Results show quick convergence of FEM ↔ Multi-Slab iterations and good agreement with experiments