1, the roller axis crosses horizontally. During the rolling process, the size of the back-up roller arch window is large or the liner and liner surface are worn, causing the support roller axis to cross in the horizontal direction. During rolling, additional axial force is generated due to the intersection of the roll axis. The larger the angle between the roll axes, the greater the axial force generated during steel rolling.
2, the surface of the tapered sleeve of the backup roller is rough, and the sealing function of the sealing ring fails due to wear during operation, causing cooling water and iron oxide scale to enter the inside of the bearing, causing the grease to lose its lubricating function, resulting in bearing damage.
3, the relative sliding friction between the spacer ring connecting the positioning bearing and the inner ring of the positioning bearing and the inner ring of the main bearing causes the end face to be burned and cracked, causing the inner ring of the positioning bearing and the main bearing to crack.
4, the roll axis crosses radially. The arc-shaped bottom pad of the back-up roller has unequal thickness on both sides, causing the roller axes to cross radially, and axial force is generated during rolling. This causes uneven load on the bearings and damage to the first row of main bearings.
5, the roller's universal joint shaft support hand cannot hold it in place under working conditions. During operation, the universal joint shaft shakes greatly, causing unstable contact between the work roll and the back-up roller. The uneven force on the work roll at the moment of steel biting produces a huge axial force, causing the bearing to overload and lock.
6. After long-term use of the universal joint of the work roll, the gap between the head bearing and the cross package is large, causing the dynamic balance to not meet the technical requirements, resulting in vibration and periodic axial impact.
(Source: Steel Rolling Home)