Nonlinear Dynamics of Torsional Vibration for Rolling Mill′s Main Drive System Under Parametric Excitation

The jointed shaft in the drivelines of the rolling mill, with its angle continuously varying in the production, has obvious impact on the stability of the main drive system. Considering the effect caused by the joint angle and friction force of roller gap, the nonlinear vibration model of the main drive system which contains parametric excitation stiffness and nonlinear friction damping was established. The amplitude-frequency characteristic equation and bifurcation response equation were obtained by using the method of multiple scales. Depending on the bifurcation response equation, the transition set and the topology structure of bifurcation curve of the system were obtained by using the singularity theory. The transition set can separate the system into seven areas, which has different bifurcation forms respectively. By taking the 1 780 rolling mill of Chengde Steel Co for example, the simulation and analysis were performed. The amplitude-frequency curves under different joint angles, damping coefficients, and nonlinear stiffness were given. The variations of these parameters have strong influences on the stability of electromechanical resonances and the characteristic of the response curves. The best angle of the jointed shaft is 4.761 3° in this rolling mill.

Extended-state-observer-based robust torsional vibration suppression for rolling mill main drive system with input saturation

A robust torsional vibration suppression strategy is proposed for the main drive system of the rolling mill subject to uncertainties,disturbances and input saturation.With given model information incorporated into observer design,an extended state observer that relies only on roller speed measurements is developed to estimate the system states and lumped uncertainties of the rolling mill main drive system.To handle the motor torque saturation,an auxiliary signal system with the same order as the plant is constructed.The error between the control input and plant input is taken as the input of the constructed auxiliary system,and a number of signals are generated to compensate for the effect of the motor torque saturation.Furthermore,a robust output feedback controller is introduced to obtain better transient and steady-state performance of the rolling mill main drive system and the stability of the closed-loop system is strictly proved via Lyapunov theory.Finally,comparative simulations are performed to verify the effectiveness and superiority of the proposed control strategy.

Analysis and Control over Noises in Main Driving System of XK-736-type NC Miller

Some concrete methods are suggested in the article to control noises in main driving system of XK-736-type NC miller by analyzing working conditions of gears in the main driving system and bearings in the spindle gearshift system. Without changing the original design, noises are reduced ideally by modifying gear top, and by controlling the profile error ; the central distance of meshing gear, the quality of the inner and outer rings of bearings ; and the fit accuracy among bearing, hole and axis. The results may provide a reference for diagnosing and maintaining in future use.

Optimal Design of a Main Driving Mechanism for Servo Punch Press Based on Performance Atlases

The servomotor drive turret punch press is attracting more attentions and being developed more intensively due to the advantages of high speed,high accuracy,high flexibility,high productivity,low noise,cleaning and energy saving.To effectively improve the performance and lower the cost,it is necessary to develop new mechanisms and establish corresponding optimal design method with uniform performance indices.A new patented main driving mechanism and a new optimal design method are proposed.In the optimal design,the performance indices,i.e.,the local motion/force transmission indices ITI,OTI,good transmission workspace good transmission workspace(GTW) and the global transmission indices GTIs are defined.The non-dimensional normalization method is used to get all feasible solutions in dimensional synthesis.Thereafter,the performance atlases,which can present all possible design solutions,are depicted.As a result,the feasible solution of the mechanism with good motion/force transmission performance is obtained.And the solution can be flexibly adjusted by designer according to the practical design requirements.The proposed mechanism is original,and the presented design method provides a feasible solution to the optimal design of the main driving mechanism for servo punch press.

Tier Ⅲ and Ⅳ cities Will Be the Main Driving Forces for Future E-business

Recently,the China E-Business Research Center(100EC.CN)released the'2015 Monitoring Report of China E-business Market'.The report says that the China E-business transaction volume amounted to 18.3 trillion yuan in 2015,up by 36.5%from a year ago,and marking an increase of 5.1 percentage points in growth rate.Meanwhile,the B2B E-business trade value totaled 13.9 trillion yuan,up

The main force driving forwards Chinese luxury market

It was during the weekend that Miss Wu lover a shop selling the luxury brand Louis VThrough the window, she could indulged in the filled with all kinds of handbags, dustcoats anheels-all she yearned for. But she tarried on thand found herself embarrassed to enter.

复杂工况下带式输送机驱动系统改造设计及应用

主斜井带式输送机经过长时间的运行,面临着变频器、控制设备老化及关键元器件备件采购困难,为了保证主斜井带式输送机的可靠运行,对某煤矿主斜井运输机陈旧的变频器和控制设备进行更换,同时对变频器和控制设备进行冗余设计。首先对原控制系统程序进行更新,实现新增变频器系统与原有变频器系统之间灵活自主切换;其次,设计新增变频器与原有变频器既可以互为备用,也可以交叉控制,实现对胶带机驱动的多样选择;然后优化主斜井带式输送机在轻载及重载工况下软起动/软停车动态过程,实现各驱动之间的平稳启动和功率平衡,抑制胶带输送机动态张力波对胶带和机械设备造成的冲击,避免撒料与叠带,延长输送机使用寿命。最后,MNS主从控制柜与变频器、主站控制柜间通讯采用专用的DP通讯线缆,设计变频器MNS主从控制柜与主站控制柜按冗余通讯进行配置,保证通信的可靠性。现场运行表明,提出的改造方案大幅提高了驱动系统和控制系统的可靠性,有效保证主斜井带式输送机的安全运行,具有推广价值。

基于振动的驱动链松弛检测方法研究及张紧装置设计

针对自动扶梯运行过程中经常产生的异常噪音、梯路振动问题,对自动扶梯传动系统振动、振动频率、张紧问题进行了研究。首先,采用频谱分析方式分析了自动扶梯运行中出现的振动频率和谐波频率情况,与理论频率相对照,分析并寻找了异常振动频率的来源;然后,对可能的振动源做了进一步验证,并对确定的振动源进行了调整,根据振动测试结果判定了调整方法是否有效;最后,设计了一款便于观察和调整的主驱动链条张紧装置,其不仅改善了振动状态,而且可以在链条断裂状态下起到安全保护作用。研究结果表明:基于各振动源的固有频率和谐波频率,将实际频率与其相对照,可以快速确定振动源;对识别出的确定振动源有针对性地进行了调整,振动值最大降低了61.5%,提高了自动扶梯测试效率;使用张紧装置后,噪音降低达3.3 dB(A),有效改善了主驱动链条振动状态,提升了运行质量。

多自由度轧机传动系统非线性非主共振扭振特性

建立含参激多自由度轧机传动系统非线性扭振动力学模型,通过坐标变换将非线性方程组解耦成独立方程,采用多尺度法得到电机扰动力矩和轧制负载力矩共同作用下非线性系统的幅频响应方程。以某厂1780轧机传动系统为实际算例,将其简化成4自由度非线性扭振模型,通过实际参数分析了非线性刚度、非线性阻尼、接轴倾角、电机扰动力矩以及轧制张力波动对传动系统超谐波共振、亚谐波共振及组合共振幅频特性的影响。用数值仿真与解析结果相比较,验证解析方法的有效性。研究结果为外扰影响下的轧机传动系统扭振特性提供一定的理论指导和参考。

轧机主传动系统异常振动仿真研究

针对某钢厂CSP轧机在轧制薄规格产品时时常出现异常振动现象,在MATLAB中建立了F3轧机主传动系统的仿真模型,对轧机在咬钢过程和异常振动过程的动态特性进行了仿真研究,并结合现场实测数据,得出了振源在主传动系统中的科学解释,为最终确定振源提供了依据。

轧机非线性传动系统冲击扭振的研究与抑制

以轴系含非线性阻尼和非线性刚度的两惯量轧机主传动系统为研究对象,建立其在冲击扰动作用下的动力学方程。分析了该系统的稳定性,得到了阻尼与刚度对系统稳定性的影响关系。采用多尺度法求解系统的一阶近似解,得到系统的扭转冲击响应,并通过对其进行数值仿真,讨论了主传动轴系阻尼非线性和刚度非线性对轧机传动系统冲击响应的影响规律,从而找出轧机系统冲击减振的方法。研究结果为抑制冲击扰动引起的轧机轴系扭转振动提供一定理论指导。

基于非线性反馈的轧机主传动机电耦联扭转系统的分岔控制

针对轧机在轧制过程中轧辊与轧件间润滑条件变化引起系统失稳振荡,以及轧机主传动系统具有复杂机电耦联的特点,应用Lagrange-Maxwell原理建立一类含非线性摩阻的轧机主传动机电耦联扭转系统的非线性动力学方程,利用非线性动态分岔理论,分析该系统的稳定性,给出系统发生Hopf分岔的充要条件及周期运动稳定性的判别方法,分析超临界分岔和亚临界分岔对主传动系统扭转振荡的影响。为抑制传动系统因Hopf分岔引起的失稳振荡,选取驱动电动机定子电压为控制量,引入电动机速度反馈,构造非线性状态反馈控制器,并采用多尺度和谐波平衡法确定控制器参数,对系统的Hopf分岔点进行转移,并控制极限环的稳定性和幅值,该控制方法简单、易实现,数值模拟验证了所设计控制器的有效性。

轧机接轴动态扭矩测量及反馈控制模型的研究

利用传递矩阵法建立起一种基于传递函数的轧机接轴动态扭矩测量模型,根据轧制负载对电机输出扭矩的影响,构造了一条控制电机输出功率的反馈回路,实现了电机的实时控制要求,达到了抑制接轴危害性扭振产生的目的,为预防接轴损坏和断裂提供了参考。

基于拓扑网络的轧机扭振分析计算

为能进行轧机主传动系统复杂分支结构的扭振分析和计算,研究了一种基于拓扑网络的扭振分析模型,模型中同时考察了内外阻尼的影响。求解模型的单支和多分支情况的动态响应。对比传统方法,文中的计算算例和仿真模拟都取得了很好的一致性。同时该法的表达便于作为控制系统的输入,为大型复杂机械主传动系统的实时主动控制和故障诊断监测开辟了一种容易实现的工程途径,也为工程中分析解决复杂多分支传动扭振及其类似问题提供了新方法。

粗轧机主传动扭振分析

分析了粗轧机主传动扭振模型及动态特性计算方法。在分析过程中考虑到轧辊与主传动动力侧之间的周向间隙对扭振响应幅度的影响,根据咬钢过程中间隙的启闭规律,基于龙格-库塔方法实现了扭振响应的数值仿真。对宝钢2050轧机R2主传动各工况进行了数值仿真,结果表明：当咬钢瞬间板坯速度大于轧辊圆周线速度水平分量时,轧辊与系统动力侧之间的接轴间隙打开,相对于间隙常闭工况,上下分支主轴的扭矩放大系数都有所增大,增幅达4%-20%。

含参激多自由度轧机传动系统非线性动力学特性

建立含参激多自由度轧机传动系统非线性扭振动力学模型,通过坐标变换将非线性方程组解耦成独立方程,应用Melnikov函数法给出谐波周期扰动力矩下系统出现混沌运动的条件。以某厂1780轧机传动系统为实际算例,将其简化成4自由度非线性扭振模型,通过理论分析和数值仿真对系统在电机扰动力矩、非线性刚度以及非线性阻尼影响下的分岔行为和混沌运动进行研究。运用分岔图、最大Lyapunov指数方法、相轨迹和Poincaré截面图对系统的全局动力学特性进行分析。结果表明,电机扰动力矩、非线性刚度以及非线性阻尼在一定范围变化时系统由周期倍化分岔、准周期运动直至混沌运动,同时出现间歇混沌现象。通过分析揭示了非线性扭振系统存在着复杂的分岔结构和混沌运动,为深入研究轧机传动系统非线性动力学行为的全局性态提供参考。

基于状态观测器的轧机主传动系统机电振动控制研究

轧机主传动系统涉及到机械、电机、自动控制以及电网等多个学科,当机电配合不好时容易产生机电振动和断带现象。在各种轧机机电振动控制方法中,用状态观测器重构无法测量的状态,如负荷力矩、连接轴力矩、轧辊速度等,实现轧机主传动系统的状态反馈控制,较好地抑制了扭振和轧制负荷外扰引起的动态速降。首先从机电动力学出发,描述了机电弹性系统模型并以现代控制理论为基础,阐述了机电振动产生的机理。然后,详细综述了基于状态观测器的轧机主传动系统机电振动控制方法,比较了其机电振动控制效果。最后展望了其未来发展方向。

考虑带钢的轧机主传动系统扭振数值研究

带钢作为连接各机架间主传动系统的纽带,其动力学特性决定着主传动系统扭转振动的动态性能。因此,考虑带钢连接的轧机主传动系统扭振模型的研究十分必要。利用ANSYS软件,建立带钢连接的双机架主传动系统有限元实体模型,并对其进行模态分析。然后对带钢施加变频力进行谐响应分析,得到各机架主传动系统中不同部位角位移随频率变化的规律曲线。最后通过对比谐响应分析与模态分析结果,进一步研究带钢与轧机主传动系统扭振之间的固有属性关系。

基于EMD分形维数的轧机主传动系统故障诊断方法研究

提出了一种基于EMD分解和分形维数的轧机主传动系统故障诊断方法.利用EMD方法对轧机主传动系统的振动信号进行分解,得到若干个基本模式分量,进一步求出包含主要故障信息的几个IMF分量的关联维数并计算它们的均方根值,作为判断轧机的故障状态和类别的特征量.实验分析表明,此方法达到了去除噪声的效果,同时增大了故障类别标准的判别距离,从而可以有效地判断轧机主传动系统系统的故障状态和故障类型.

轧机主传动系统自抗扰控制器设计与应用

轧钢过程中的负荷扰动容易激起机电振动,这严重影响板带材的产量和质量.为了抑制机电振动,针对轧机主传动系统存在不确定外部扰动和未建模动态的特点,首先建立了轧机主传动系统的模型,将不确定性外扰和未建模动态视为一个综合扰动项,然后利用扩张状态观测器对综合扰动项进行观测和补偿,设计了一种不依赖于对象模型的轧机主传动系统鲁棒控制器.仿真结果证明:该控制器比外扰负荷观测器控制系统具有更好的抗扰动能力,同时对系统内部参数如负载转动惯量、转矩常数等的摄动也具有较强的鲁棒性,有效抑制了由于轧制负荷周期性变化和轧制负荷突变引起的机电振动.首次将扩张状态观测器和自抗扰控制技术应用到轧机主传动系统机电振动控制中,并通过实验证明了该方法的有效性和优越性.