Research On Dynamic Modeling And Horizontal Vibration Characteristics Of Cold Rolling Mill Roll System

After simplifying the structure of the four-high cold rolling mill,this paper found that the vertical structure and torsion structure of the rolling mill will cause vibration in the horizontal direction of the rolling mill,which will produce a complex state of force between the strip and the roll.Aiming at the horizontal vibration of the cold rolling mill during the rolling process,the following researches are carried out in this paper:Through analysis,it is found that there is an offset between the work roll and the backup roll in the vertical direction of the cold rolling mill,so that the pressing force of the hydraulic cylinder has a horizontal component.The universal joint shaft drives the work roll and there will be additional horizontal force and the rolling interface mixed lubrication state.The horizontal component of the friction generated.Considering these forces as the input excitation that mainly causes the horizontal vibration of the work roll,the corresponding vibration mechanics model is established.Analyze the vibration characteristics of the nonlinear vibration model when it contains different types of excitation frequencies.The multi-scale method is used to calculate the non-fixed length of the system,and the amplitude-frequency characteristic equations of the cold rolling mill horizontal direction main resonance,super-harmonic resonance,sub-harmonic resonance and combined resonance are obtained.Through the simulation analysis of the factors affecting the vibration of the cold rolling mill,it is found that the change of rolling mill parameters and different resonance states will have a significant impact on the amplitude,resonance point,resonance area and spine line position of the system vibration.The change of the coefficient of the linear stiffness term has obvious effects on the natural frequencies of the main vibration,superharmonic vibration and combined vibration,and the amplitude of the system vibration will decrease with the increase of the coefficient;however,the increase of the coefficient in the sub-harmonic vibration will cause the system to suffer The vibration amplitude and vibration area become larger.The coefficient of the nonlinear stiffness term will bend the spine of the system,causing jumping phenomena and unstable regions;the amplitude of the main resonance and superharmonic resonance does not change with the coefficient of the nonlinear stiffness term,but the peak point will shift and cause instability The expansion of the area;the sub-harmonic resonance amplitude and the vibration area will decrease with the increase of the coefficient,and the combined resonance is opposite to the sub-harmonic vibration.In several excitation frequency states,the increase of the damping term coefficient and the decrease of the excitation force amplitude will inhibit the vibration amplitude of the rolling mill.Analysis of the dynamic response of the cold rolling mill showed that the gap between the bearing seat and the pillar of the archway will cause the positive and negative amplitude of the horizontal vibration to be asymmetric.In the sub-harmonic vibration,the vibration amplitude is the smallest and close to symmetry.In the main vibration and combined resonance,the system moves in a period-doubling period.In the super-harmonic and sub-harmonic vibrations,the system gradually tends to a chaotic period.There are many dominant frequencies of vibration in superharmonic motion and combined motion,which easily cause vibration.Changing the system gap found that reducing the system gap can effectively suppress the rolling mill vibration.The change of external disturbance force will cause the system to produce chaotic phenomena.In the main resonance,superharmonic vibration and combined vibration,with the amplitude of the external disturbance force,the chaotic phenomenon alternately occurs.In the sub-harmonic resonance,the system motion is relatively stable.In different excitation states,the amplitude of the external disturbance can be controlled to avoid the chaotic period area generated by the system,thereby suppressing the vibration of the rolling mill.