冷轧板带轧机多重耦合动力学建模及辊缝动态油膜激励下的振动特性研究

The vibration of rolling mills is a worldwide problem for the steel industry. And this problem has not been solved completely due to the lack of understanding of vibration law. In this project, the non-stable characteristics of roll gap lubrication condition affected by cold rolling process are analyzed, and the prediction model of strip surface roughness is established by experimental test. The improved Kalman equation is presented and the dynamic rolling force under the dynamic excitation of the roll gap oil film is given in combination with the hydrodynamic theory. At the same time, considering the uneven distribution of the air-gap magnetic field of the motor caused by the sudden load changing, the machinery-electric-hydraulic multiple coupling dynamic model covering mechanical, electrical and lubricating systems is established by using the Reynolds equation and the Lagrange-Maxwell principle. The vibration responses of coupling system under dynamic rolling force will be studied by means of incremental harmonic balance method, and the influence of rolling mills’ structures and rolling process conditions on vibration amplitude are analyzed. The Filippov convex method and Poincare mapping theory are used to analyze the sliding bifurcation phenomena under mixed friction. The instability mechanism of the multi-coupling system is given, and the boundary conditions of the stability will be determined according to the global dynamic behavior of the system. The above research will be helpful to the improvement of the theory of rolling mills’ vibration, and an effective method to suppress the vibration is given from the aspects of rolling mills structure design and rolling process optimization.

轧机振动是困挠钢铁行业的世界性难题，受振动规律认识所限，该问题至今尚未彻底解决。本项目深入剖析辊缝润滑条件受冷轧过程影响而出现的非稳态特性，通过实验测试建立带材表面粗糙度预报模型，提出改进的Kalman方程并结合流体力学理论给出辊缝油膜动态激励下的动态轧制力，同时考虑电机气隙磁场因负载突变导致的不均匀分布，综合运用Reynolds方程和Lagrange-Maxwell原理建立涵盖机械、电气、润滑系统的机-电-液多重耦合动力学模型；采用增量谐波平衡法，研究耦合系统在动态轧制力作用下的振动响应，分析轧机结构和工艺条件对振动幅值的影响规律；运用Filippov凸方法和Poincare映射理论分析混合摩擦状态下的滑动分岔现象，给出多重耦合系统的失稳机理，并依据系统的全局动力学行为确定稳定性的边界条件。以上研究将有助于轧机振动理论的完善，从轧机结构设计和轧制工艺优化方面给出抑制振动的有效方法。

高端板带材生产能力已成为衡量一个国家工业水平的重要标志，而轧制过程中的振动现象已成为制约钢铁行业发展的世界性难题。本项目深入剖析辊缝润滑条件受冷轧过程影响而出现的非稳态特性，给出混合润滑状态下辊缝间总摩擦应力表达式，并通过数值积分建立了冷轧带钢动态轧制力模型，经实际生产数据验证该轧制力预报模型具有较高的预测精度。根据电机原理和电磁场理论，给出交流同步电机气隙磁场能，并结合能量法计算电磁力矩的表达式，同时考虑轧机主传动系统间隙和辊缝混合润滑条件的影响，建立了轧机垂直-扭转耦合系统、水平-垂直耦合系统、含间隙和混合摩擦状态下的机电耦合系统动力学模型。采用多尺度法研究了轧机水平-垂直耦合动力学系统的主共振和内共振响应，并给出了主共振和内共振幅频特性曲线，分析了外扰力及轧机非线性结构参数对轧机耦合振动特性的影响规律；利用IHB法分析了混合润滑条件下轧机主传动机电耦合系统的周期运动，研究发现在三次超谐波共振情况下，外激力幅值或粘附系数增加时，系统正弦响应中的谐波因素增加；在主共振情况下当外激力幅值增加时，系统振动幅值增大，粘附系数变大时，系统主共振幅值变小，共振区域基本不变。研究了含间隙和混合摩擦的轧机主传动机电耦合系统的Hopf分岔现象，研究表明随着动压摩擦系数的变化，系统发生超临界Hopf分岔和亚临界Hopf分岔行为，其中亚临界分岔行为对轧机主传动系统的破坏性更大；针对含间隙和混合摩擦的轧机主传动机电耦合系统的滑动分岔问题，提出了一种基于Filippov方法的扩展算法，结果表明随着混合摩擦系数的增大，系统由稳定的周期运动，演变为擦边滑动分岔，随后穿越分界面，进入混沌运动状态，导致轧机主传动系统发生扭转振动。以上研究对完善轧机振动理论起到重要促进作用，从轧机结构设计和轧制工艺优化方面给出抑制振动的有效方法。