Optimization of roll mechanical profiles in a continuous annealing line for steel strips

Abstract

In order to set the mechanical characteristics to the target of the customer, cold rolled steel strips are annealed at high temperature in batch or continuous annealing furnaces.

In a continuous annealing furnace, the strip passes over thermally deformed rollers. The shape of the furnace rollers at high temperature depends on this thermal deformation and on a mechanical profile on the roll. An accurate setting of the mechanical roller profiles is of major importance in order to avoid tracking problems, specially in the first part of the furnace, or buckling problems when the strip is wide and processed at high temperature.

Since the last 15 years, the part of the strips processed in the continuous annealing lines is dramatically increasing in the world; the products are also getting thinner and wider and the processing speeds higher, causing lateral strip displacement and strip deformations, like buckles, more critical.

In this context, it was important to accurately estimate the thermal deformation of the rollers and the critical conditions for buckling. JRSID and SOLLAC developed calculation models of roller thermal expansion, and wrinkling criteria. Those models were used to set new values of mechanical profiles for rollers in the annealing furnaces of SOLLAC.