【作者】 张明；

【导师】 彭艳； 陈连生；

【作者基本信息】 燕山大学 ， 机械设计及理论， 2017， 博士

【摘要】 板带产品的升级换代不可避免的增加了轧机设备运行载荷,轧制过程中振动问题愈来愈突出,对轧机系统动态特性的研究迫在眉睫。板带材的轧制过程是一个高速、重载、高精度以及多维耦合的复杂非线性动态生产过程。轧机系统是由轧机垂直压下系统、辊系运动系统、主传动系统,以及轧件的变形系统等多个子系统组成,其动态特性是由多个不同物理属性的子系统共同作用而决定的。本文以某钢厂热连轧精轧机组第二架精轧机(F2)研究对象,基于现场轧机振动测试现象,从轧机传动系统、轧制界面摩擦阻尼特性和辊系摆动特性三个方面开展轧机系统的动态特性研究。本文对F2轧机振动问题进行综合测试,开展压靠实验、爬坡实验、以及振动实验。详细地分析主要振动现象,掌握热轧机的主要固有振动特性、振动形式(受迫振动和自激振动)和振动机理等动态特性,挖掘热轧机稳定轧制的共性技术,指导本课题主要研究内容的开展。综合考虑传动系统中弧形齿啮合的结构参数,建立弧形齿啮合的稳态力学模型,研究啮合力和附加力矩产生机理和分布规律。引入动态位移和动态负载力矩,研究弧形齿接轴的动态啮合力和附加力矩的变化规律。考虑弧形齿动特性建立轧机传动系统的动力学模型,分析传动系统的固有特性,以及轧机传动系统振动机理。探讨弧形齿接轴的工作参数和轧制工艺对轧机传动系统稳定性的影响规律。结果表明:轴间倾角越大、轧制速度越大、弧形齿磨损越大时,轧机传动系统稳定性越低。弧形齿接轴的应用既给轧机系统带来了便利,同时也存在着一定的潜在危害,需要制定合理的维护和检测制度,避免引起轧机剧烈的振动。根据轧制变形区的动态几何关系,建立轧件动态流动速度模型。考虑轧制界面混合摩擦状态(滑动区、制动区和停滞区)力学特征和分布规律,建立轧制界面动态摩擦模型,并根据现场数据进行验证。基于该模型分析轧制界面摩擦动态变化规律,分别研究轧制界面扭转方向的摩擦负阻尼和水平方向摩擦负阻尼产生机理,以及主要轧制工艺参数对轧制界面稳定性的影响规律。基于轧制界面动态摩擦模型建立轧机扭转-水平耦合振动模型,结合轧制工艺参数、轧机结构以及现场测试数据分析轧机扭转自激振动产生的机理。结果表明:压下量越大、轧件变形抗力越大、轧辊半径越大、摩擦系数越小、轧制界面摩擦负阻尼越大,轧制稳定性越低。研究成果可以为合理轧制工艺规程的制订或优化提供理论指导。考虑辊系横向动态载荷分布、轧机结构两侧不对称性、结构间隙、辊系垂直运动与水平运动耦合关系以及外界干扰力,建立热轧机辊系摆动(平动和转动)动力学模型。求解辊系的固有特性,揭示轧机辊系振动机理和振纹分布规律。探讨弧形齿磨损程度、轧制速度和结构间隙对辊系的稳定性影响。结果表明:轧机辊系存在着周期运动和混沌运动,对轧机振动控制和抑制有一定的指导作用。综合考虑弧形齿动特性的轧机传动系统动力学模型、混合摩擦状态的热轧机轧制界面动力学模型和轧机辊系摆动动力学模型三个子系统模型之间的耦合关系,建立热轧机整体耦合动力学模型。根据现场的振动形式,分别仿真分析弧形齿啮合冲击时和轧制界面摩擦自激振动时轧机系统动态行为特征。揭示轧机系统之间的耦合关系、振动能量传递路径和振动机理。热轧机动力学模型体系的建立一方面有助于深入揭示热轧过程中不同形式振动发生机理,通过轧制工艺优化和轧机结构控制来提高轧制过程的稳定性。另外,在轧机设备故障诊断方面,该模型体系的完善能够为有效、精确地预测轧制设备的健康状态提供理论指导依据,推动轧制设备智能化管理。更多还原

【Abstract】 The upgrading of the strip product inevitably increases the running load of the rolling mill equipment,and the vibration problem is becoming more and more prominent in the rolling process.So,the research on the dynamic characteristics of rolling mill system is imminent.Rolling process is a high-speed,high-load,high-precision and complex nonlinear dynamic production process.And the dynamic characteristic is composed of press system,roll system,main driving system and steel deformation system,which are determined by the interaction of multiple subsystems of different physical attributes.This paper makes a hot four-high mill system as the research object,the dynamic characteristics of rolling mill are studied from three aspects: the driving system,the damping characteristic of rolling interface friction and the characteristic of roll swing basing on the phenomena of rolling mill vibration test.The second finishing rolling mill(F2)was tested synthetically,and the oppressive experiment,climbing experiment and vibration experiment were carried out.The main vibration phenomena were analyzed in detail,and the dynamic characteristics of the hot rolling mill were mastered,such as the main vibration forms(forced vibration and self-excited vibration)and the vibration mechanism.In addition,the common technologies of stable rolling process were excavated,which guided the main research contents of this subject.The steady mechanical model of the arc tooth gear meshing was established considering the structural parameters of the arc tooth meshing in the driving system.The mechanism and distribution law of the meshing force and the additional torque were studied.And then the dynamic meshing force and the additional torque were studied by considering the dynamic displacement and dynamic load torque.The driving system dynamic model considering with the dynamic characteristics of arc tooth gear was established for the first time.Then the inherent characteristics and vibration mechanism of the driving system were analyzed.The influences of the working parameters and the rolling process on the stability of the driving system were discussed.The results showed that the larger the axial tilt Angle is,the bigger the rolling speed is,the higher the wear degree is,the lower the stability is.The application of the arc tooth gear shaft provides convenience to the rolling mill system,and there is also a potential hazard.It need maintain and test timely,to avoid causing severe vibration.The dynamic flow velocity model of steel was established according to the dynamic geometric relationship in the deformation zone.Considering the distribution of the mix friction state(sliding zone,braking zone and stagnation zone)in the rolling interface,the dynamic friction force model of the interface was established.Based on this model,the dynamic variation law of friction force in the interface was analyzed.The mechanism of torsional friction negative damping and horizontal friction negative damping in the rolling interface were studied respectively,as well as the influence of rolling parameters on the rolling interface stability.Then,the torsional-horizontal coupling vibration model of rolling mill was established based on the dynamic friction force model,and the self-excited vibration mechanism was discussed according to the rolling process parameters,the rolling mill structure and the field test data.The results showed that the larger the reduction amount is,the larger the deformation resistance is,the larger the roll radius is,the smaller the friction coefficient,the larger the friction negative damping is,and the stability is lower.It could provide theoretical guidance for making reasonable rolling process.Considering the transverse load distribution,the asymmetry on both sides of the rolling mill structure,the structural clearance,the coupling relationship between vertical motion and horizontal motion and the external disturbance force,the dynamic model of the swing vibration(translational and rotational)was established in the hot rolling process.The inherent characteristics of the roll system were solved,and the vibration mechanism and distribution of chatter marks were revealed.At last,the effects of arc tooth gear wear degree,rolling speed and structural clearance on the stability of roll system were discussed,which could guide the vibration control and suppression.The dynamic relationship of the three sub-systems namely the driving system dynamic model considering with the dynamic characteristics of arc tooth gear,the dynamic friction force model on the interface considering the distribution of the mix friction state,and the dynamics model of roll system were studied.And the whole coupling dynamic model of hot rolling mill was established.The dynamic behavior of the rolling mill system was simulated and analyzed.The coupling relationship between the rolling mill system,the transfer path of vibration energy and the vibration mechanism were revealed.The establishment of the dynamic model of hot rolling mill is helpful to reveal the mechanism of different vibration forms,and it can improve the stability of rolling process by optimizing the rolling process parameters and rolling mill structure.In addition,the improvement of the model system can provide theoretical guidance for the effective and accurate prediction of the rolling equipment health status,and promote the intelligent management of the rolling equipment.更多还原