Applications of advanced models to prediction of flatness defects in cold rolling of thin strips

Sami Abdelkhalek (1) , Rebecca Nakhoul (2) , Hamid Zahrouni (3) , Pierre Montmitonnet (2) , Nicolas Legrand (1) , Michel Potier-Ferry (3)

1 Research and Development Industrial operations
2 CEMEF - Centre de Mise en Forme des Matériaux
3 LEM3 - Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux

Flatness defects in thin strip cold rolling are a consequence of roll thermo-elastic deformation, from which heterogeneous strip plastic deformation results. When flatness defects manifest on line, buckling reorganizes the stress field in the pre- and post-bite areas. This might impact strain and stress fields in the bite, an effect which had been neglected. Two coupled Finite Element Method (FEM) approaches are presented here to examine to what extent such potential in-bite / out-of-bite feedback determines the in-bite fields and the flatness of the strip. Using both methods and comparing with the standard case where buckling is not accounted for, it has been shown5 that (i) taking buckling into account results in a completely different stress field and fits correctly the measured on-line residual stress profile under tension (by "stress-meter rolls"); (ii) coupling buckling in the post-bite area and the rolling model, whatever the technique, changes little the in-bite fields. The models are applied here to several questions, namely the impact on flatness of heterogeneous temperature fields and of thinner edges, and the effect of friction on optimal setting of a flatness actuator, Work Roll Bending (WRB).

Mots clés: Rolling; Thin Strips; Finite Element Method; Friction; Flatness Defect

Domaines: Matériaux

Sami Abdelkhalek, Rebecca Nakhoul, Hamid Zahrouni, Pierre Montmitonnet, Nicolas Legrand, et al.. Applications of advanced models to prediction of flatness defects in cold rolling of thin strips. 15th International Conference on "Advances in Materials and Processing Technologies - AMPT 2012, Sep 2012, Wollongong, Austria. ⟨hal-00724898⟩