Abstract
An expression for the dynamic rolling force of a rolling mill is derived in terms of the vibration and process parameters by analyzing the dynamic rolling process. A nonlinear vibration model of the rolling mill rolls is established. The amplitude-frequency and bifurcation equations are obtained using a multi-scale approximation method, to solve the dynamic equation with time-delayed displacement control. With a 1780 rolling mill as an example, it is found that the primary and cubic stiffness due to the dynamic rolling force and external excitation lead to a jump phenomenon in the vibration system, making it unstable. When the gain coefficient and delay time are taken reasonably, the amplitude of the vibration system is reduced, the resonance region shrinks, and the jump is eliminated. Finally, the bifurcation topological curve corresponding to the transition set of the vibration system is studied using the singularity theory, with and without time-delayed displacement control. The results show that the vibration of the rolling mill rolls can be restrained by varying the initial parameters and through the time-delayed displacement control. Thus, the established vibration model of the rolling mill is verified, and the effectiveness of the time-delayed displacement control in reducing the rolling mill vibration is confirmed.
Highlights
The vibration of rolling mill rolls is a challenging problem for steel enterprises
Liu et al [10] considered the influence of friction coefficient on the horizontal vibration of a workpiece, studied the bifurcation behavior of the vibration system using the singularity theory, and specified the unstable regions of rolling mill vibration
To obtain an accurate vibration model with a more practical vibration characteristic, we analyzed the variation in the parameters in the deformation zone between the rolls, derived a dynamic rolling force expression considering the various vibration and process parameters, and established a nonlinear vibration model of the roll system based on the dynamic rolling force
Summary
The vibration of rolling mill rolls is a challenging problem for steel enterprises. Extensive studies are being conducted on restraining the vibration to ensure that the system runs smoothly and that the quality of the rolling products is maintained [1,2,3]. Zeng et al [12] established the vertical-horizontal-torsional coupling dynamic model of a rolling mill under the condition of nonlinear friction and calculated the Hopf bifurcation points under different rolling speeds; their research results are useful for optimizing the rolling process. Sun et al [17] obtained a type of rolling force with a time-delayed characteristic under the influence of roller dynamic movement based on the rolling theory. To obtain an accurate vibration model with a more practical vibration characteristic, we analyzed the variation in the parameters in the deformation zone between the rolls, derived a dynamic rolling force expression considering the various vibration and process parameters, and established a nonlinear vibration model of the roll system based on the dynamic rolling force. The correctness of the model and the effectiveness of the time-delayed displacement control for vibration suppression were verified
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