Model on coupling of roll wear-fatigue and equivalent conversion of rolling kilometers

The twenty-high rolling mill production line of a certain steel plant adopts a small batch, multi steel type and multi specification production mode. This production mode significantly complicates the on-site assessment of roll operating conditions. Coupled with the strict requirement for roll profile control accuracy in high-precision roll‑ing mills, the on-site design of roll-related processes such as roll change cycles and roll grinding consumption lacks sufficient theoretical support and has to rely on previous production experience. As a result, the production cost caused by roll consumption remains relatively high while production efficiency is unsatisfactory. To solve the above problems, the equipment and process characteristics of the twenty-high rolling mill in the steel plant were fully con‑sidered. First,the structural characteristics of the twenty-high rolling mill rolling system were analyzed. The applica‑bility of commonly used roll wear models and roll fatigue crack propagation models in engineering was discussed, and some key parameters in the models were regressed and calculated. A wear and fatigue calculation model suitable for on-site twenty-high rolling mills was proposed. Furthermore, in response to the current situation of indepen‑dently considering roll wear and roll fatigue, a study was conducted on the coupling method of roll wear and roll fatigue. Finally, to address the issue that traditional rolling kilometers were difficult to guide roll change in smallbatch and multi-specification rolling, the concept of equivalent rolling kilometers was introduced. The damage degree was defined by integrating the roll profile damage caused by roll wear and the damage induced by fatigue cracks. With the comprehensive damage degree used as a bridge for converting rolling kilometers between different loads, a set of equivalent rolling kilometers algorithms for the twenty-high rolling mill was developed. These algo‑rithms can convert the roll rolling kilometers under different working conditions into those under the target working condition. When applied on-site, this technology can evaluate the roll status under different operating conditions using equivalent rolling kilometers, helping to enhance on-site understanding of roll conditions and optimize roll change timing. On the one hand, this approach helps reduce roll consumption and production costs. On the other hand, by accurately determining roll change timing, it can reduce production preparation time and thus improve pro‑duction efficiency.