板带轧机主传动系统非平稳轧制条件下的机电耦合振动特性及失稳机理研究

With the increase of rolling speed, the vibration of rolling mill system has become more and more prominent. The vibration phenomenon of rolling mill has not been solved due to the comprehension limitation of vibration mechanism. Aiming at this problem, this project establishes the electromechanical coupling dynamic model of rolling mill under the action of nonlinear electromagnetic torque, based on the principle of Lagrange-Maxwell, and studies the mechanical and electrical system as a whole. In order to improve the stability of rolling process as the goal, nonlinear theories such as the incremental harmonic balance method, normal form, singularity and so on are used to study time-frequency domains vibration characteristics of main drive system when rolled piece appears elastic-plastic deformation hysteresis, to analyze the primary resonance, super harmonic resonance and sub-harmonic resonance of the electromechanical coupling system. And non-smooth system theories such as discontinuity mapping, Filippov convex method and so on are used to study the grazing bifurcation and sliding bifurcation phenomenon of electromechanical coupling system under the gap and dry friction condition, to give the boundary conditions of system instability. Through the above study, the relationship between the electromechanical structure parameters、rolling conditions and the dynamic behavior of the main drive system is confirmed. Finally, it reveals the electromechanical coupling vibration regularity and instability oscillation mechanism of the rolling mill in the process of non-smooth rolling. After completing the project, it will further promote the development of rolling mill vibration theory, and provide new ideas and approaches for restraining vibration phenomena in rolling production.

随着轧制速度的提高，轧机系统振动问题日益突出,受振动机理认识所限，轧机振动现象尚未得到解决。针对这一问题，本项目根据Lagrange-Maxwell原理建立非线性电磁力矩作用下的轧机机电耦合动力学模型，将机械和电气系统作为统一的整体进行研究。以提高轧机轧制过程中的稳定性为目标，运用增量谐波平衡法、规范形、奇异性等非线性理论研究轧件弹塑性滞后变形时主传动系统的时频域振动特性，分析机电耦合系统的主共振、超谐共振和亚谐共振行为；并采用不连续映射、Filippov凸方法等非光滑系统理论，研究间隙和干摩擦工况下机电耦合系统的擦边分岔和滑动分岔现象，给出系统失稳的边界条件。通过上述研究，明确机电结构参数、轧制条件与主传动系统动力学行为间关系，最终揭示轧机在非平稳轧制过程中的机电耦合振动规律及失稳振荡机理。项目完成后将进一步促进轧机振动理论的发展，为抑制轧制生产中的振动现象提供新的思路和途径。

轧机振动是世界范围内金属板带材轧制生产中普遍存在和亟待解决的问题，这种振动过程会造成带钢表面形成明暗条纹，增加板带厚度误差，严重的振动甚至会引起系统失稳，造成断带或设备损坏等事故，危害生产安全。目前，全球钢铁企业的部分轧机都不同程度地存在振动甚至失稳振荡问题，严重制约钢铁工业的发展。. 本项目针对轧机振动问题，开展以下两方面研究：. 1、建立轧机非平稳轧制条件下非线性机电耦合动力学模型。非平稳轧制过程中负载变化使电机转速出现波动，这种波动状态导致电机的气隙磁场能分布不均匀，本项目基于广义耗散Lagrange-Maxwell原理，考虑气隙磁场能的不均匀分布，给出电磁力矩随轧制速度变化的非线性关系，建立非线性电磁力矩作用下的轧机主传动机电耦合动力学模型，为开展非平稳轧制时的机电耦合振动行为提供合理的动力学模型。. 2、研究间隙状态下轧机机电耦合系统的擦边分岔行为及振动抑制方法。轧辊处发生打滑时，轧机系统在万向接轴、扁头等处的间隙便会打开，造成系统振荡。本项目基于建立的机电耦合动力学模型，构造不连续映射，并结合碰撞理论，研究间隙出现瞬间及其前后的局部动态特性，重点分析外部激励作用下擦边分岔行为导致的失稳机理，给出通过改变电机输出转矩抑制该类型振动发生的理论依据。. 通过以上研究，本项目给出了轧机机电耦合系统擦边点附近的拓扑结构图，建立了临界情形下系统擦边分岔时的切换映射，并结合Floquet理论系统的研究了含间隙的机电耦合系统在非平稳轧制条件下的动力学行为演变过程，研究表明擦边分岔所导致的混沌现象是导致轧机失稳振荡的主要原因，针对这一发现，本项目设计了一种自适应脉冲控制器，仿真实验表明该控制器可以有效的抑制系统产生的非线性振动。. 以上研究揭示了含间隙的轧机机电耦合系统在非平稳轧制条件下的失稳机理，明确了轧制条件和结构参数变化对轧机振动行为的影响规律，为避免非平稳轧制过程中轧机机电耦合系统的振动行为提供了有针对性的抑制措施。