Modelling and industrial experiment on the dynamic deviation of rolling force during high precision rolling process

The dynamic deviation of rolling force during the rolling process is influenced by various coupling factors, including mill stiffness on the operating and driving sides, initial strip specifications, and roll crossing. These factors frequently lead to sickle bending of the strip and bearing wear. Although this dynamic deviation is crucial in the rolling process, the existing literature falls short in studying the mechanism of this deviation, both theoretically and experimentally. As a result, operators in industrial plants predominantly rely on experience to assess it and are unable to formulate specific adjustment plans. In this work, physical and mathematical models of rolling force deviation are developed to elucidate the underlying formation mechanism, taking into account the contact deformation of the roll system, plastic deformation of the strip and roll crossing models. Analysis of production data reveals that the dynamic deviation of rolling force exhibits three distinct fluctuation patterns: positive deviation, negative deviation, and alternating positive and negative deviation. Numerical simulations and industrial experiments are conducted to investigate the influencing factors and evolution rules of rolling force deviation under various rolling conditions. The results indicate that dynamic deviation increases with the growth of centreline deviation and wedge amount of strip, and exhibits a complex fluctuation pattern as the crossover angle increases. This is confirmed by both numerical simulations and experimental results. Based on these analytical results, several improvement methods have been implemented in industrial plants to reduce the dynamic deviation of rolling force. These include reducing stiffness deviation on both sides of the mill, narrowing the bearing housing clearance, and ensuring mill symmetry.