Reducing thickness variation of hot rolled steel strip by non-circular back-up roll geometry

Abstract Typically, back-up rolls in hot strip mills are equipped with sliding bearings and it is common to use a key that prevents relative motion between the conical sleeve and the roll shaft. The key groove causes deformation of the sleeve under load. This sleeve 'spring' is observed as rolling force variation, which causes systematic thickness variation of the steel strip. Although there is a keyless bearing construction on the market, an alternative solution was studied. A non-circular camlike geometry that compensates the sleeve spring was ground on the back-up rolls by a three-dimensional grinding method. As a result, ∼50% of the rolling force and the thickness variations, which were synchronised with the back-up rolls of the mill stand studied in the present paper, were reduced.