Vibration Characteristics of Hot Rolling Mill Rolls Based on Elastoplastic Hysteretic Deformation

Rongrong Peng,Peiming Shi,Xingzhong Zhang

doi:10.3390/met11060869

Rongrong Peng, Peiming Shi + Show 1 more

Open Access

https://doi.org/10.3390/met11060869

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Abstract

Based on the analysis of the influence of roll vibration on the elastoplastic deformation state of a workpiece in a rolling process, a dynamic rolling force model with the hysteresis effect is established. Taking the rolling parameters of a 1780 mm hot rolling mill as an example, we analyzed the hysteresis between the dynamic rolling force and the roll vibration displacement by varying the rolling speed, roll radius, entry thickness, front tension, back tension, and strip width. Under the effect of the dynamic rolling force and considering the nonlinear effect between the backup and work rolls as well as the structural constraints on the rolling mill, a hysteretic nonlinear vertical vibration model of a four-high hot rolling mill was established. The amplitude-frequency equations corresponding to 1/2 subharmonic resonance and 1:1 internal resonance of the rolling mill rolls were obtained using a multi-scale approximation method. The amplitude-frequency characteristics of the rolling mill vibration system with different parameters were studied through a numerical simulation. The parametric stiffness and nonlinear stiffness corresponding to the dynamic rolling force were found to have a significant influence on the amplitude of the subharmonic resonance system, the bending degree of the vibration curve, and the size of the resonance region. Moreover, with the change in the parametric stiffness, the internal resonance exhibited an evident jump phenomenon. Finally, the chaotic characteristics of the rolling mill vibration system were studied, and the dynamic behavior of the vibration system was analyzed and verified using a bifurcation diagram, maximum Lyapunov exponent, phase trajectory, and Poincare section. Our research provides a theoretical reference for eliminating and suppressing the chatter in rolling mills subjected to an elastoplastic hysteresis deformation.

Highlights

A hot rolling mill is an important piece of equipment in the iron and steel industry
Equation (14) is the dynamic equation for the hysteretic nonlinear vertical vibration of a hot rolling mill considering the effects of elastoplastic deformation hysteresis and parametric stiffness between the rolls
By eliminating θ in Equation (23), we can obtain the 1/2 subharmonic resonance amplitude-frequency response equation for the rolling mill rolls based on the elastoplastic hysteresis deformation of the workpiece: 1 2

Summary

Introduction

A hot rolling mill is an important piece of equipment in the iron and steel industry. Zhang et al used the plastic finite element method to calculate the plastic deformation characteristics of a strip steel; considering the thermal expansion and wear of rolls, a 3D model of the hot strip rolling process was established [15]. The elastoplastic hysteresis deformation characteristics of the workpiece will make the rolling force to exhibit a hysteretic nonlinear characteristic. A dynamic rolling force expression with the hysteresis effect was derived by considering the nonlinear effect of the elastoplastic hysteresis deformation of a workpiece in a hot rolling process. R h R avherage (3) (3) deformation velocity of the workpiece, affecting the rolling force during the elastoplastic deformatioFnroomf thEequwaotiroknpi(e3c)e, .we find that the roll vibration affects the average deformation velocity of the workpiece, affecting the rolling force during the elastoplastic deformation of the workpiece

Rolling Force Fp in the Plastic Zone

A eiω1T0

Solution of the Subharmonic Resonance Response

Solution of Internal Resonance Response

Conclusions and Observations