【作者】 孙建亮；

【导师】 彭艳；

【作者基本信息】 燕山大学 ， 机械设计及理论， 2010， 博士

【摘要】 板形和板厚精度是衡量板带材质量的重要指标。轧机系统是复杂的多变量非线性系统,其动力学特性非常复杂,且对板形板厚质量有很大影响。目前对板厚系统的研究主要是单项和局部的研究,针对轧机整体系统动态模型研究很少;对板形系统的研究,主要是基于静态预设定理论的研究,对面向板形板厚控制的轧机系统动态建模和仿真的研究很少。本文面向板厚和板形控制,对轧机系统动态建模进行了深入的理论研究和仿真验证。考虑轧制过程中各参量间复杂的关系,建立了面向板厚控制的轧机机电液系统动力学模型。模型包括轧制过程动态模型、机架辊系动态模型和液压压下系统模型三个子模型。各模型之间相互耦合,相互影响,是一有机整体。根据三者的内在联系,建立其耦合模型,并将其线性化,得到面向板厚控制的轧机系统多输入多输出线性化动态模型。该模型从轧机主体全局角度建模,区别于以往主要针对轧机系统单项和局部模型的研究。基于建立的板厚控制系统线性化动态模型,采用H_∞混合灵敏度简化算法,为电液IGC系统设计了鲁棒控制器;基于H_∞标准控制,采用遗传算法,优化选取了加权函数,使加权函数的选取不再过分依赖设计者的经验;为基于测厚仪监控的厚度控制闭环设计了鲁棒控制器。仿真结果表明,所设计的鲁棒控制器具有较好的动态性能,比常规PID控制器具有更好的抗干扰性能和鲁棒性,证明了所设计控制器的有效性。建立面向板形板厚控制的轧机系统动力学模型,必须建立包括轧制方向、轧机垂直方向和轧辊轴向(轧件宽度方向)的动力学模型,其中考虑轧辊轴向非线性特性的动力学模型是关键。本文将轧辊看作弹性连续体,区别于以往将轧辊看作刚性质点的理论,基于连续体动力学理论,建立四辊轧机辊系横向自由振动模型和受迫振动模型。求解了辊系的固有频率、主振型和振动方程;研究了不同受力形式下,辊系的动态特性,并进行了仿真分析。该模型是建立面向板形板厚控制的轧机动态仿真模型的基础。轧机的整体动态性能,不仅与轧机本身的动力学特性有关,还与轧制过程中运动带钢动态特性相关。本文基于运动梁理论和运动薄板理论,分别建立了轧制过程中运动板带的二维和三维动力学模型;基于轧制理论,确定了带钢的张力方程和张应力分布方程。将带钢张力方程和张应力分布方程与运动板带二维动力学模型和三维动力学模型结合。基于Galerkin截断方法,将动力学偏微分方程离散。确定了运动板带系统的固有频率及其影响因素,研究了轧制过程中运动带钢的稳定性,并对其进行实时仿真。建立面向板形板厚控制的轧机系统动态仿真模型。首先,建立轧机辊系横向振动模型和轧制过程模型的耦合动态模型(简称为耦合动态模型)。然后,建立轧件-辊系耦合模型,用于修正补偿耦合动态模型。最后,兼顾动态模型和静态模型特点,基于数值算法,将耦合动态模型和轧件-辊系模型耦合,得到基于板形板厚控制的轧机系统动态模型,并进行了仿真分析。该模型可对轧制过程进行模拟,能反映板形板厚综合动态信息,为虚拟轧制提供理论基础,并为先进控制理论应用提供平台。本文基于动力学理论,建立了面向板形板厚控制的轧机系统动力学模型理论体系。突破传统的静态建模理论,发展了轧制理论,对于推动轧钢机械系统动态建模,开发新的板带轧制工艺和设备,具有重要的理论意义和实用价值。更多还原

【Abstract】 The shape and thickness qualities of the strip are very important indexes, and the rolling mill system is a complex multivariable nonlinear system, the dynamic characteristics of the rolling mill are complex which have strong influence on the shape and thickness qualities. At present, the studies on the strip thickness system mainly concentrated on the individual items and partial items, and the study on the integral mill system based on thickness control is rare; the studies on the strip shape system mainly concentrated on the static shape preset theory, and the study on the mill dynamic model and simulation based on shape control is rare. So that, based on thickness and shape control, the dynamic model building theory and simulation of mill system was deeply studied.Take the complex relationship of parameters in the rolling process into consideration, the integral dynamic model of 4-h mill based on thickness control was built. The dynamic model includes the rolling process model, the dynamic model of mill stand-rolls and the dynamic model of hydraulic servo system. The three models coupled together and are a organic whole. According to the relationship among the three models, the coupled model was established and linearized. Then, the MIMO transfer function of 4-h mill system was established. This model is different from the individual items and partial items of mill system, but it was built from the global perspective.Based on the linearized dynamic model based on thickness control, the robust controller was designed for the electro-hydraulic system based on the simplified H_∞mixed sensitivity method. The H_∞robust controller is designed for the thickness control system based on the mixed sensitivity robust control theory. Simulation results and comparison with the effect of PID controller show that the robust controller designed has better disturbance attenuation performance for parameter uncertainty and external disturbance, and the effective of the controller was approved.In order to build the dynamic model of mill system based on shape control, the dynamic models which include the rolling direction, the vertical direction and the axial direction of rolls must be built firstly. In this paper, the rolls were taken as elastic continuous bodies, which was different from the theory taking the rolls as lumped masses. The free and forced transverse vibration models of rolls were built based on continuous body dynamic theory. The natural frequency, principal mode and motion equations were determined; the dynamic characteristics of rolls were studied when the rolls were acted by different forces, and the simulation was made. This model is the basic model of the dynamic model based on shape control.The integral dynamic performance of tandem rolling mill is not influenced by the dynamic of rolling mill, but influenced by the moving strip. The two dimensional model and three dimensional model of moving strip in the rolling process was established based on moving beam theory and moving sheet theory respectively. Then, substitution of the tension equation and stress distribution equation into the two dimensional dynamic model and three dimensional dynamic model, based on Galerkin truncation method, the partial differential equation was discrete. The natural frequencies of moving strip are determined. The stability of moving strip was studied and the simulation in time domain was made.The dynamic model of rolling mill system based on the shape and thickness control was established. First, the coupled model of rolling process and transverse vibration model of rolls was built (here simply called coupled dynamic model). Then, the srip-rolls coupled static model was built and used to compensate the dynamic model. Last, considering the characteristics of static model and dynamic model, coupled the dynamic model and static model, based on numerical method, the dynamic model of rolling mill based on shape and thickness control was established and the simulation was made.The theory system of dynamic model building of rolling mill based on shape and thickness control was established in this paper. The static model building theory was broken, and the rolling theory was developed. It is significant for developing the dynamic model building of rolling equipment, developing new rolling technology and equipment.更多还原