工作辊轴承滚道波纹度故障下板带轧机垂直振动特性研究

Vertical vibration characteristics of a strip mill under the fault of raceway waviness of work roll bearing

考虑滚道波纹度的影响,基于Hertz弹性接触理论建立了工作辊故障轴承的动态非线性接触力模型。在此基础上,考虑轧机辊系结构振动的影响,建立了工作辊轴承滚道波纹度故障下板带轧机的三自由度非线性垂直振动模型。通过数值仿真分析了波纹度波数、幅值、轴承间隙以及转速等参数对轧机轧辊非线性振动特性的影响。研究发现:在故障轴承非线性接触力的激励下,不同波纹数振动频谱图中出现不同的故障特征频率、倍频以及与轧辊转频的组合频率;当波纹数等于滚动体数目时,轧辊将产生剧烈振动。随着轧辊轴承波纹度幅值的增大,故障特征频率及其三倍频幅值显著增加,通过合理改变轴承间隙能够有效抑制,但过大的轴承间隙会降低系统稳定性。在中等转速范围内,轴承波纹度故障将导致轧机出现超谐波共振、主共振等多种非线性振动行为。此外,相对于外圈故障,轧机系统对工作辊轴承内圈波纹度故障的表现更为敏感。

Considering the effect of raceway waviness,a dynamic nonlinear contact force model for work roll failure bearings was established based on Hertz elastic contact theory.On this basis,the three-degree-of-freedom nonlinear vertical vibration model of a strip mill under the fault of raceway waviness of work roll bearings was established considering the influence of structural vibration of the mill roll system.The effects of parameters such as ripple degree wave number,amplitude,bearing clearance and rotational speed on the nonlinear vibration characteristics of mill rolls were analyzed by using numerical simulation.It is found that under the excitation of the nonlinear contact force of the faulty bearing,the vibration spectrum of the signal under different ripple numbers shows different fault characteristic frequencies,multiplier frequencies and combined frequencies with the roll rotation frequency.When the ripple number is equal to the number of rolling bodies,the roll will produce violent vibration.With the increase of roll bearing ripple degree magnitude,the amplitude of the characteristic frequency of fault and its triplet frequency increase significantly,which can be effectively suppressed by reasonably changing the bearing clearance,but excessive bearing clearance will reduce the system stability.In the medium speed range,the bearing ripple fault will lead to a variety of nonlinear vibration behaviors in the mill such as superharmonic resonance and main resonance.In addition,the rolling mill system is more sensitive to the performance of the inner ring corrugation failure of the work roll bearing compared to that of the outer ring.