【作者】 曾春；

【导师】 徐长生；

【作者基本信息】 武汉理工大学 ， 机械设计及理论， 2010， 博士

【摘要】 汽车工业是工业发达国家国民经济的支柱产业,汽车工业对钢板质量和品种要求越来越高,促使钢铁生产厂家不断革新工艺技术和改进质量。平整机是汽车钢板生产工艺中采用小压下量的冷轧机,平整机在高速生产轧制中有时会出现原因不明的颤振。某冷轧厂平整机支撑辊在使用一段时间后,辊面常出现明暗相间的振纹,然后在平整过程中将振纹印在带钢表面上,严重影响了带钢表面质量和生产效率。解决平整机的振动问题是提高国产化汽车板带材质量面临的一个重要课题。本文以该平整机为研究对象,以轧制理论、线性振动理论、非线性振动理论、振动诊断理论及轧制过程摩擦与润滑理论为依据,进行了以下研究工作：(1)建立平整机主传动系统动力学模型,并得到模型元件的等效转动惯量和等效扭转刚度,分别用集中质量法和有限元法计算该动力学模型固有特性,并对两种方法计算结果进行比较。计算并分析主传动系统的模态柔度与能量分布。分别计算了无阻尼和有阻尼时各轴段的扭矩放大系数,验证了主传动系统动力学特性。(2)建立平整机垂振系统动力学模型,并得到模型元件的等效质量和等效刚度,分别用集中质量法和有限元法计算该动力学模型固有特性,并对两种方法计算结果进行比较。计算并分析垂振系统的模态柔度与能量分布,根据分析结果对平整机垂直系统动态优化设计提出合理建议。(3)建立平整机工作辊水平运动方程和水平动力学模型,并对该模型进行振动仿真和稳定性分析,从理论上分析其工作界面负阻尼的产生原因。通过相图、Poincare截面、最大Lyapunov指数等多种方法来描述由负阻尼导致的水平摩擦自激振动特性。根据工作辊水平和垂直运动之间的影响关系,建立平整机上辊系模态耦合振动系统的动力学模型和数学模型,由数值仿真得出工作辊在轧制界面动摩擦和模态耦合的作用下产生自激振动的行为。(4)结合轧制界面油膜厚度模型和工作辊水平动力学模型,建立平整机轧制力和垂直动态刚度随工作辊水平颤振速度变化的数学模型,得出水平摩擦颤振速度、轧制界面和垂直动态刚度之间存在耦合关系的结论。根据上述数学模型和平整机垂振动力学模型,数值仿真结果显示,该耦合关系导致平整机垂振系统的自激振动行为,并由此影响带钢振纹的生成。基于以上研究内容和成果,利用建模分析,结合现场振动测试信号的分析结果,验证上述关于平整机振动机理分析的正确性,为生产现场抑制平整机振动及振纹产生提供理论指导。同时,依据振纹产生机理提出抑振工艺措施,实践表明,这些措施为解决带钢表面振纹的产生起到良好效果。更多还原

【Abstract】 Automotive industry is supporting industry in those countries with advanced industry. More and more requirement focused on quality and variety of automobile leaf-spring, thus result in iron and steel production enterprise continuously reform technic and improve quality. Temper rolling mill a kind of cold rolling mill with small quantity of reduction, it is used in production technology process of automobile leaf-spring. Sometimes doubtful vibration occured when temper rolling mill runs with high speed. In one cold rolling plant, light and shade chatter mark appeared on the surface of back-up roll of the temper rolling mill after a period of usage, the chatter mark may be impressed on the surface of strip steel, thus severely affected production efficiency and surface quality of strip steel. Solving problem of temper rolling mill vibration is an important subject faced during the course of improve quality of domestic strip steel.The studying work of this dissertation is based on the theory of rolling, linear vibrations, nonlinear vibrations, diagnosis of vibrations, friction and lubrition in rolling, the temper rolling mill was regarded as research object, the following studying work was proceeded in the dissertation:(1) The dynamic model of torsional vibration is created, the equivalent mass and the equivalent rigidity of the model elements are obtained. Using lumped mass method and finite element method to calculate the nature characteristic of the model, the results calculated by the above two methods also be compared. Modal flexibility and energy distribution of tortional vibration system are calculated and analyzed. Torque amplified factor of each shaft is calculated under condition of damping and undamping, thus verified the dynamic character of torsional vibration system.(2) The dynamic model of vertical vibration is created, the equivalent mass and equivalent rigidity of the model elements are obtained. Using lumped mass method and finite element method to calculate the nature characteristic of the model, the results calculated by the above two methods also be compared. Modal flexibility and energy distribution of vertical vibration system are calculated and analyzed. Based on the analysis results, resonable suggestion about dynamic optimum design of temper rolling mill’s vertical vibration is proposed.(3) The horizonal equation and the horizonal dynamic model of temper rolling mill’s working roll are created, vibrate simulation and stability analysis of the model are proceeded, the reason which caused negative damping of the rolling interface is analyzed. The character of horizonal friction self-excited vibration caused by negative damping is described through phase picture, Poincare section, maximum Lyapunov exponent, et, al. According to the influence of horizonal and vertical movement of the working roll, the dynamic model and mathematic model of the top roll system modal coupling vibration system are created, the conclusion of working roll’s self-excited vibration caused by the effect of rolling interface dynamic friction and modal coupling is drawn through numerical simulation.(4) Combined with working roll’s horizonal dynamic model and oil film thickness model at the entrance of rolling deform area, the mathematic model of temper rolling mill’s rolling force and dynamic rigidity change with working roll’s horizonal chatter velocity is created. The conclusion of coupling relationship among horizonal chatter velocity, rolling interface and vertical dynamic rigidity is drawn. According to the above mathematic model and vertical dynamic model of the temper rolling mill, the simulate result shows that the coupling relationship result in self-excited vibration of temper rolling mill’s vertical vibrate system, and therefore influenced generation of chatter mark on the surface of strip steel.Based on the above studying results and combined with the analysis result of the local testing signal, the correction of temper rolling mill’s vibration mechanics which analyzed in the frontal chapters is validated, all of these provide theoretics guide for restraining chatter mark and vibration of temper rolling mill in production field. According to the production mechanism of chatter mark, technics measures are put forward to restrain vibration at the same time, practise result shows that these measures take good effect on restraining chatter mark on the surface of strip steel.更多还原