离散辅助闭环在轧辊偏心补偿中应用的仿真研究

在板带轧机液压板厚自动控制系统中,扰动补偿控制是控制系统中的一个重要组成部分。扰动控制基本是开环控制,补偿效果难以准确保证。轧辊偏心补偿通常是在计算得到轧辊偏心量后,通过扰动控制进行补偿。轧辊偏心是一个周期量,如果投入的计算补偿量幅值或相位偏差较大,将会补偿一个错误量,有可能恶化产品厚差精度。该文根据闭环控制基本原理,在进行轧辊偏心补偿时,构建出一个辅助的闭环系统,根据计算或检测得到的相位,通过从离散存取矩阵中读取对应的偏心补偿量进行补偿,并根据控制期望值、实际输出值及原偏心补偿量对厚度的补偿影响量计算出补偿偏差,经辅助闭环控制器计算出修正偏心补偿量,代替原离散存取矩阵中对应相位处的偏心补偿量,实现对偏心补偿量的滚动优化,从而改善补偿效果,进而提高补偿精度。通过不同工况下的仿真运行曲线显示了离散辅助闭环控制在轧辊偏心补偿应用中的可行性,为轧辊偏心补偿提供了一种有效的新途径。     

叶片辊轧机高精度调整机构运动精度分析

为了实现叶片辊轧机轧辊位置的精确调整,建立了包含蜗轮蜗杆、滚珠丝杆、斜板等零部件刚度影响下的运动误差方程,研究了传动机构刚度、轧辊初始安装预紧量对其运动精度的影响,并通过实验对仿真结果进行了分析,结果表明:当轧辊初始安装预紧量为0时,轧辊的运动精度受零部件传动刚度、轧辊移动阻力的影响较大,当预紧量大于0.04 mm时,轧辊的移动精度提高,但会加剧轧辊与斜铁之间的磨损,结合现场应用,确定0.04 mm是轧辊初始安装的最佳预紧量。     

轧辊磨损及其预报

在对轧制摩擦特点进行分析的基础上，论述了轧辊磨损形成机理，分析了各种工作辊磨损预报模型。提出了今后工作辊磨研究工作的建议。     

四辊轧机有载辊缝解析模型研究

针对轧制过程中轧辊的弹性变形和轧辊与轧件间的相互作用，通过对四辊轧机辊系变形和受力状况的分析，从理论上详细推导了直观的有载辊缝形状函数，明确了有载辊缝形状函数与相关因素的对应关系。同时，为了验证辊缝解析模型的准确性，采用该模型对某铝热连轧机的精轧末机架的出口板凸度进行了理论计算，并与在线测得数据进行比较，结果表明：该模型计算精度高，相对误差较小(低于15％)。该模型不但为板形的控制以及轧制板凸度的建模提供了理论基础，还为预报板形、研究板带截面上任一点的板凸度提供了方便。     

四立柱分体式20辊轧机辊系的刚度特性分析

20辊轧机的横向刚度、纵向刚度对板形、板厚的控制非常重要,研究不同状态下轧机的刚度变化规律对板形、板厚综合控制的精度具有十分重要的意义。在三维弹性有限元模型的基础上,建立了四立柱分体式20辊轧机辊系的有限元模型。利用该模型研究板宽、中间辊窜辊量变化对轧机辊系横向刚度和纵向刚度的影响,为轧机板形、板厚控制量的调整提供了参考依据,也为板带轧制过程中板型、板厚在线设定,以及控制模型的研究和优化,提供了理论基础。     

基于阶比跟踪的带钢冷轧过程轧辊偏心信号分析

针对板带轧制厚度控制过程中轧辊偏心扰动难以在线测量和准确表达问题,提出新的系统解决方法。根据板带轧制原理,建立轧辊偏心在线软测量模型,通过采集得到的压下缸位移、轧制力、出口板厚等数据对轧制过程中的轧辊偏心信号进行计算,从而解决轧辊偏心难以在线测量的问题。为解决轧制过程速度变化带来的偏心信号频率和周期的变化问题,在轧辊偏心分析中,引入阶比跟踪技术计算角域等角度采样时标,通过拉格朗日插值计算实现角域重采样,把轧制过程数据的时间序列转化为轧辊转动等角度采样的角域序列。同时,通过厚度信号的角域平移,解决由板厚信号滞后带来的数据不匹配问题。利用小波滤波、相干时间平均法实现依据带钢冷轧过程数据进行轧辊角域偏心波形的分析和提取,为实现轧辊偏心的有效补偿打下基础。     

“1+4”铝热连轧轧制力自学习

在铝热连轧精轧生产过程中,轧制力的预报精度直接影响板厚和板凸度控制精度。针对河南某1+4铝热连轧机现场轧制力预报精度较低的问题,根据现场采集的大量轧制数据,建立了轧制力模型自学习算法,并用细菌觅食优化算法对自学习中的增益系数进行了优化,提高了轧制力预报精度。     

单点增量成形制件整体精度研究

以典型圆锥台作为研究对象,由材料的变形机理出发,解析制件整体精度的机理和主要影响因素。采用Box-Behnken 设计(BBD)试验方法,对主要影响因素中的工具头直径、层间距、板厚、成形角设计四因素三水平曲面响应试验,建立两个方向上几何误差的二阶响应模型,得到工艺参数对制件在水平方向和垂直方向上精度的单一及交互影响规律。最后,利用响应模型对两个方向几何误差进行同步最小优化,得到制件整体精度最优时的工艺参数组合：工具头直径6 mm、层间距0.5 mm、板厚1 mm、成形角45 °,此时两个方向的几何误差分别为1.914 6 mm和-0.157 mm,实现了制件整体精度的工艺优化和稳健控制。     

斜轧毛管壁厚偏心预报模型及影响工艺分析

为改善无缝钢管生产工艺,开展斜轧毛管壁厚偏心预报模型及影响工艺分析。从实际生产过程与理论层面进行研究,对引起斜轧毛管壁厚偏心的各项因素进行了分析研究结果表明测试毛管壁厚都在纵向线上形成了具有周期性特征的分布形态,呈现近似正弦曲线的特点,最大和最小壁厚之间保持180°的对应状态。在毛管壁厚不均中存在比例超过80%以上。实测得到的壁厚偏心比预报值更小。毛管壁厚偏心值受到毛管壁厚以及毛管温度偏心因素的明显影响,呈现正相关特点;轧辊转速与辊肩高度则对毛管壁厚偏心产生了负影响的作用,逐渐增大这两个变量后,发生了毛管壁厚偏心值降低现象。该研究为提升无缝钢管壁厚尺寸控制精度提供了一定的参考价值,具有很好的实际指导效果。     

带钢冷轧过程辊系径向变形的数据挖掘与预报

在带钢冷轧过程中,辊系径向变形会影响带钢的厚度精度,并且难以在线检测.依据自动厚度控制(Autogaugecontrol,AGC)系统固有的测试系统,充分利用采集到的出口厚度、压下位移、轧制力、轧制速度等数据,根据厚差公式进行数据挖掘,对辊系的变形进行挖掘计算.为了解决由于测厚仪安装距离造成的厚差信号滞后问题,在挖掘计算前依据轧制速度进行数据重新匹配和整理,在挖掘计算后采用指数平滑法对计算结果进行平滑,并按照趋势外推法进行当前辊系径向变形值的预报.采用平滑系数自适应算法进一步提高预报精度.将辊系径向变形值的挖掘和预报方法在某四辊轧机轧制数据上进行应用,取得比较清晰的变形规律和完整变形过程.为进一步研究轧辊辊系径向变形规律和补差方法,进而提高厚度控制精度奠定了基础.     

Coupled dynamic modeling of rolls model and metal model for four high mill based on strip crown control

The crown is a key quality index of strip and plate,the rolling mill system is a complex nonlinear system,the strip qualities are directly affected by the dynamic characteristics of the rolling mil.At present,the studies about the dynamic modeling of the rolling mill system mainly focus on the dynamic simulation for the strip thickness control system,the dynamic characteristics of the strip along the width direction and that of the rolls along axial direction are not considered.In order to study the dynamic changes of strip crown in the rolling process,the dynamic simulation model based on strip crown control is established.The work roll and backup roll are considered as elastic continuous bodies and the work roll and backup roll are joined by a Winkler elastic layer.The rolls are considered as double freely supported beams.The change rate of roll gap is taken into consideration in the metal deformation,based on the principle of dynamic conservation of material flow,the two dimensional dynamic model of metal is established.The model of metal deformation provides exciting force for the rolls dynamic model,and the rolls dynamic model and metal deformation model couple together.Then,based on the two models,the dynamic model of rolling mill system based on strip crown control is established.The Newmark-β method is used to solve the problem,and the dynamic changes of these parameters are obtained as follows:(1) The bending of work roll and backup roll changes with time;(2) The strip crown changes with time;(3) The distribution of rolling force changes with time.Take some cold tandem rolling mill as subject investigated,simulation results and the comparisons with experimental results show that the dynamic model built is rational and correct.The proposed research provides effective theory for optimization of device and technological parameters and development of new technology,plays an important role to improve the strip control precision and strip shape quality.     

A new mathematical model for predicting the diameter expansion of flat ring in radial–axial ring rolling

An accurate prediction for the diameter expansion is quite essential for the ring rolling with large diameter since it determines the compatibility between the work rolls and the deformed ring in kinematics, so that the rolling stability and the final forming quality of the ring are influenced. A new mathematical model for predicting the diameter expansion of the flat ring in the radial–axial rolling process has been proposed, in which the variation of cross section, the particularity of initial rolling phase, and the effect of slip are all taken into consideration. Based on the proposed mathematical model, a 3D-FEM model for the radial–axial ring rolling process has been developed, and the corresponding experimentation has also been carried out. The diameter expansion in the simulation shows a good agreement with that in the experimentation. The forming quality comparison concerning the circularity, coaxiality, and tilting of the rolled ring has been executed between the former and new proposed method. The result indicates that the new mathematical method is very helpful to control the forming stability and hence improve the ring rolling quality significantly.     

Research on forming precision of flexible rolling method for three-dimensional surface parts through simulation

Flexible rolling is a novel forming process for three-dimensional surface parts using a pair of bendable rolls. By controlling the distribution of the gap between the upper and lower forming rolls in the rolling process, the sheet metal is nonuniformly thinned in the thickness direction and the longitudinal elongation is different in the width direction of the sheet metal, which makes the sheet metal deform in rolling direction. With the rotation of the bendable rolls, the sheet metal is deformed consecutively and a three-dimensional surface part could be obtained. A small experimental device has been designed. Finite element analysis (FEA) model is established. Spherical surface and saddle surface are simulated, and their experimental results are presented. The major purpose of the present work is to analyze the forming precision of flexible rolling and the reasons for the shape errors through simulated and experimental results. The results demonstrate that the proposed process is a feasible and effective way of forming three-dimensional surface parts.     

产品概念结构设计中的公差进化模型和算法

在产品概念结构设计自动化技术基础上，研究了产品公差设计过程及其特点，提出了四层产品公差结构模型。应用局部公差分配模型与公差设计过程建立了全局公差优化理论模型，提出了以保证产品总精度需求为目标的概念结构设计阶段公差的同步设计算法。实例表明，提出的公差进化模型和算法，避免了人为建模工作，大大提高了公差设计效率和质量，为快速完成多方案的并行设计奠定了基础。     

高精度方、矩形管孔型的优化设计

针对高精度方、矩形管孔型进行优化设计计算 ,包括管坯尺寸的确定 ,各机架延伸系数的分配 ,各机架减径及孔型高度、弯曲角度、弯曲半径的精确计算。如水平辊、立辊孔型均采用对角开口方式 ,成型质量便会提高 ,并使钢管表面划伤降低到最小程度。     

辊系装配密封性试验及精度控制

在大型热矫正机装配过程中,作为矫正机核心部件的辊系部分由于辊系本身的质量问题造成停机事故时有发生,给用户造成很大的经济损失,因此提高辊系装配的密封性及精度控制势在必行。     

带钢冷轧AGC系统的数据挖掘与厚差溯源

为了获得轧制过程各扰动量的精确信息，改善冷轧带钢厚度控制（AGC）的控制效果，在AGC系统中引入了误差分析和误差溯源理论，对厚差产生的各种主要因素和环节作出了分析和描述。依托轧制过程数据库的大量数据，运用数据挖掘理论对轧制数据进行综合分析，将其中包含的主要干扰量进行逐一分离和溯源，通过回归分析确定各干扰量的性质与特征，并对回归分析得到的干扰量模型用神经网络进行校验。     

Continuous-forming method for three-dimensional surface parts combining rolling process with multipoint-forming technology

Flexible rolling is a novel forming process for three-dimensional surface parts, which combines the rolling process with multipoint-forming technology. This process employs a pair of forming rolls as a forming tool. By controlling the gap between the upper and lower forming rolls, residual stress caused by the longitudinal non-uniform elongation of sheet metal makes the sheet metal generate three-dimensional deformation. In this paper, the improvement of the process is introduced that the middle curve radius of the roll gap is much larger than the transverse curvature radius of the forming surface in the forming process. The forming roll rotates around its own axis easily because of the small bending deformation which is suitable for producing three-dimensional surface parts including the wide sheet metal with a relatively small transversal curvature radius. The forming principle is set forth, and corresponding formulations are presented. Finite element analysis model is established, and spherical and saddle surface are simulated. The forming precision and the causes of the shape errors are analyzed through simulated results. The experimental equipment is designed and their experimental results are obtained. Simulation results are in well agreement with the experimental results, which verifies the feasibility of using simulation to guide the experiment. The results of both numerical simulations and experiments show that the proposed process is a feasible and effective way of forming three-dimensional surface parts.     

推力轴承工艺与工装的改进

针对推力轴承加工过程中存在的锻造工艺落后、留量大、精度差、切断宽度大等问题,对锻造工艺进行了改进,由自由锻4件合锻改为碾环锻造8件合锻,减少了加工留量,提高了效率;工件分离由车刀切断改为锯片锯断,减少了切断留量和端面留量,节约了原材料,提高了加工工效,降低了生产成本;对锯床进行了技术改造,并制作了新工装,为工艺改进奠定了基础。     

轧制过程轧辊磨损数学模型试验研究

利用自行开发研制的DTW-166热磨损试验机,研究了高铬铸铁、高速钢轧辊的磨损量与工艺参数的关系。分析了现场轧制过程中正在使用的轧辊磨损模型,对该数学模型在结构上进行了改进,利用各种条件下的大量试验数据,回归得到热轧带钢轧辊磨损的数学模型。该数学模型的建立为提高设定计算中的板形控制功能提供了理论基础。