Cause of damage

The working conditions of the rolls are the most complex among the mill components. Residual stresses and thermal stresses are generated during the preparation process of rolls prior to manufacture and use. It is further subjected to various periodic stresses, including bending, torsion, shear, contact stress and thermal stress. The distribution of these stresses along the roll body is uneven and constantly changing, due not only to design factors, but also to the wear of the rolls over time, the constant changes in temperature and roll shape. In addition, rolling conditions are often anomalous. Rolls can also be damaged by thermal stress if they are not cooled properly after use. Therefore, in addition to wear, rolls often suffer from cracks, fractures, spalling, indentations and other local damage and surface damage. A good roll should have a better match between its strength, wear resistance and other performance indicators. In this way, it is not only durable under normal rolling conditions, but also less damaged in the event of some abnormal rolling conditions. Therefore, when manufacturing rolls, the metallurgical quality of the rolls should be strictly controlled or supplemented by external measures to enhance the bearing capacity of the rolls. Reasonable roll shape, hole shape, deformation system and rolling conditions can also reduce the roll workload, avoid local peak stress, and prolong the roll life.