Normal inter-roll contact stiffness model considering friction factor
With the growing demand for high-quality strip products,the precision requirements for strip mill equip-ment have become increasingly stringent,and the precision of the mill equipment plays a pivotal role in ensuring product quality.The contact stiffness between rolls in the strip mill is a fundamental parameter that not only ensures product quality but also significantly impacts the stability of the rolling process.Presently,the rolling mill roll con-tact stiffness model takes into account the elastic deformation of the roll system and the force relationship.Howev-er,during the service cycle of the rolls,the surface condition continually deteriorates,leading to changes in the roll contact friction state.The conventional roll contact stiffness model does not consider these contact friction factors,resulting in an inability to accurately reflect the rolling process and the influence of the roll surface state on the inter-roll contact stiffness.To address this limitation,a comprehensive investigation into the inter-roll contact stiffness of rolling mills requires the establishment of a model that considers friction.This study leverages fractal theory to model the rough surface of rolls and analyzes the deformation state of micro-convex body contacts on the rolls rough surface,along with the curved surface contact characteristics of the roll system.As a result,a normal contact stiff-ness model is developed,which incorporates frictional effects between rolls.The 2 250 mm hot rolling mill is used as a case study to explore the impact of fractal parameters,contact parameters between rolls,and the size of the roll system on the inter-roll contact stiffness.The findings indicate that fractal dimension and fractal roughness are posi-tively and negatively correlated with inter-roll contact stiffness,respectively,suggesting that a rougher roll surface results in lower inter-roll contact stiffness.Additionally,an increase in the inter-roll contact friction coefficient leads to a gradual decrease in inter-roll contact stiffness,while larger inter-roll contact loads and roll diameters result in higher inter-roll contact stiffness.The model established in this paper can provide a parametric basis and theoretical basis for evaluating the accuracy of rolling mill equipment.
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