Deformation of slab in vertical rolling has been simulated in laboratory scale mills to investigate width deviation. Rolling load and torque formula have been derived by dimensional analysis technique. The error of formulas is within ±10 percent. The limit of slab buckling at heavy width reduction has been formulated. The shape of localized deformation at the edge of slab has been modeled. The width spread of edge-rolled slab after thickness reduction has been investigated on the basis of Siebel's formula. These deformation formulas have been extended to that of head and tail end of slab where unsteady deformation is predominant. Finally, resultant width shortage pattern has been quantitatively predicted by applying principle of superposition. The validity of the model has been checked at a hot strip mill.
On the basis of these fundamental equations, an optimum edge rolling schedule has been derived to minimize width shortage at the head and tail end of coils. This optimum schedule requires allowable heavy width reduction from the last pass to the upper stream in edger stands. Better yield has been achieved through application of this schedule at hot strip mills.