一种新型的基于最小二乘回归St14钢变形抗力模型的方法

冷连轧的主要工艺参数为轧制力和前滑,而轧制力和前滑设定计算的精度取决于轧件的变形抗力和摩擦因数的精度,变形程度是影响变形抗力的一个重要因素,将所选变形抗力回归模型经过取对数等变换成线性函数,以鞍钢生产的St14钢为例,利用现场实际数据通过最小二乘来逐次拟合变形抗力回归模型中的系数。在同一轧制条件下,摩擦因数用3种不同的获得方法,其中前2种是由实测前滑值反算得到的,以使所得模型能够很好地与实际生产的数据相吻合。用回归出的3种不同变形抗力模型,分别带入轧制力迭代公式进行计算,所得轧制力基本与实测轧制力相符,其中由斯通公式拟合出的变形抗力回归模型计算出的轧制力平均误差很小,由此可以选出最优的变形抗力模型来应用于实际生产中轧制力和前滑的预设定。     

带钢冷连轧材料变形抗力模型研究

针对冷连轧轧制过程的特点,变形程度是影响变形抗力的一个重要因素。建立了变形抗力的机理模型,并将理论模型与实际数据相结合。采用某钢厂生产的低碳钢08AlA稳定轧制时的现场实测数据,利用最小二乘逐次回归变形抗力模型中的各个参变量,并选用不同的方法来获得摩擦系数,选出与实际生产数据相吻合的最佳模型。将回归出的不同变形抗力模型,分别代入轧制力迭代公式进行计算,通过比较与实测轧制力的误差,选出最优的形抗力模型应用于实际生产中轧制力和前滑的预设定。     

不锈钢冷连轧轧制力显函数模型的开发与应用

针对不锈钢冷连轧生产工艺,提出动态变形抗力概念,利用四辊可逆冷轧机和Inston高速拉伸实验机进行轧制-拉伸实验,在MMS-200热模拟实验机上测定不锈钢的应力-应变曲线,建立不锈钢动态变形抗力模型。在Hill方程的基础上建立了轧制力显函数模型,并通过变形抗力和摩擦因数的逆向回归计算实现模型的在线自学习。提出了适合轧制力模型的可信度评估方法,引入Theil不等式系数法,依据TIC值定性分析了模型的适用性。最终确立了适合于冷连轧生产的精确的轧制力显函数模型,并将其应用到生产实践中。统计结果表明：冷连轧过程中轧制力的模型计算值与实测值的相对误差小于3.67%,该模型具有良好的计算精度和较好的泛化能力,适合于工业生产实践。     

冷连轧过程控制系统的自适应功能实现

针对冷连轧过程控制系统的模型设定计算的特点与需求,建立了轧制力、前滑、扭矩和辊缝自适应系数的计算模型,同时给出了冷连轧过程摩擦因数和变形抗力参数的反馈计算模型,进而完善和优化冷连轧轧制参数模型。为实现实测数据的采集与处理,设计了基于事件、计时器和消息的3种实测数据采集方法。最终完成冷连轧过程控制的自适应功能开发,并将其应用到生产实践中。结果表明,该自适应功能模块有效保证了在线模型设定计算的快节奏,大大提高了原始模型的计算精度,有利于提高系统稳定性和运算效率,适合于工业生产实践。     

提高轧制力设定精度的一种离线优化方法

轧制力参数设定是轧机设定模型的核心参数之一,对决定成品卷的厚度精度及板型质量至关重要。京唐酸轧二级模型计算轧制力时采用Bland-Ford-Hill公式,经分析确定影响轧制力计算精度的参数主要为变形抗力和摩擦力因数。因此提出了一种利用特定钢种的初始历史实际轧制数据离线调整其变形抗力和摩擦力因数的方法,从而提高本钢种在线轧制力模型的设定精度。实际应用表明,使用通过此方法优化后的变形抗力和摩擦力参数计算轧制力,轧制力设定模型的精度得到了明显提高,能够满足在线控制需求。     

An Analytical Model for Dependence of Force and Forward Slip on Speed in Cold Rolling

An explicit analytical method for determining approximations for roll force and forward slip for strip rolling is introduced. It reproduces all main predictions of classical strip theory, but is completely free of any numerical algorithms. Nevertheless, for extreme cases of cold rolling, like foil or skin pass rolling, more sophisticated algorithms are still needed. For the friction coefficient in the roll gap and its increase from the entry to the neutral point also explicit relations are proposed. In the framework of this analysis, they are sufficiently precise for cold rolling with one‐phase lubricants and stochastic surfaces. Only a single parameter of adaptation is needed, the microscopic friction coefficient μ_micro. The quality of the total model is illustrated by means of the dependence of roll force and forward slip on railing speed. For this purpose measured process data (four different pass‐schedules, seven to ten coils each) for cold rolling of copper with rolling oil is analyzed.     

TRB薄板变厚度轧制中前滑理论模型和数值模拟

根据变厚度轧制特点和前滑定义,推导了一种变厚度轧制的前滑值的理论模型.用MARC软件建立变厚度轧制的有限元模型,针对四种不同变厚度区形状的轧件在轧制摩擦因数为0.08和0.1工况条件下的轧制过程进行了数值模拟.此外,采用轧制试验方法实测了总前滑量.对比分析结果表明：前滑理论模型的计算值与有限元数值模拟结果接近,两种方法计算所得前滑值的差值小于0.005.与常规恒厚度轧制中稳定前滑值不同,在变厚度区轧制时,前滑值在0.02～0.10波动.变厚度区的压下率越大,其前滑值也越大;较小变厚度区斜度设计和低的摩擦因数会使变厚度轧制有更好的轧制稳定性和小的前滑波动范围.TRB变厚度轧制试验也验证了前滑理论模型的精度.减薄轧制实测前滑值和计算值偏差大与变形区应变状态及增加的打滑趋势有关.     

Neural Network Friction Model for Cold Strip Rolling

A neural network friction model with very good prediction accuracy was developed on the basis of industrial data. Simulative calculation indicated that the accuracy of rolling force and motor power calculation can be improved using the calculated friction coefficient. It was found that reduction ratio and deformation resistance of strip has more effects than other parameters, and the effects of most parameters are affected by rolling speed.     

Simplified Weighted Velocity Field for Prediction of Hot Strip Rolling Force by Taking into Account Flattening of Rolls

The weighted velocity field was simplified for analysis of hot strip rolling. Using the field and GM （geometric midline） yield criterion, the deformation power, friction power and shear power were obtained respectively. Summing the partial power contributions, the total deformation power for strip rolling was presented. Then, by minimizing the power function, the rolling force was obtained; meanwhile, considering the effect of roll elastic flattening, iterative calculation of the roll radius was carried out until the radius was convergent. On line data were corn pared with the calculated results to verify the model accuracy. It was indicated that the calculated rolling forces were basically in agreement with the measured ones since the maximum error was less than 10.0%. Moreover, the effects of various rolling conditions such as thickness reduction, friction factor and shape factor, upon separating force, location of neutral angle, and stress state coefficient were discussed systematically.     

Evaluation on some important force models for cold strip rolling

To improve the accuracy of rolling force prediction, some important force models were evaluated through applied computation for cold rolling of low carbon steel and aluminum alloy according to measured data on lab mill. The effects of model structure and three important variables ‐ flow stress, contact length and friction coefficient ‐ on the precision of computed force were quantitatively studied. Flow stress was measured with plane‐strain compression test, contact length was based on elastic flattening of work‐roll by Hitchcock, and friction‐coefficient was determined by rolling strain and numerical iteration. In steel rolling Bland & Ford integration model and Bryant & Osborn algebraic equation are better in accuracy than Ekelund and Parkins. In aluminum rolling all the models produce large deviations ΔF_R = 10–20% if flow stress, contact length and friction coefficient are determined with the same method as steel rolling. The elastic deformation of aluminum strip is now taken into account for its low elastic modulus. An effective method to determine plastic and elastic contact has been developed in this investigation. The accuracy of force computation is obviously improved for aluminum rolling.     

基于极限静摩擦力矩的轧机打滑预测模型

 冷连轧轧制过程中,当轧制转矩大于轧辊与轧件间的极限静摩擦力矩时,轧辊与轧件之间将出现相对滑动,从而导致打滑的发生。为减少因打滑导致的冷轧带钢带钢表面缺陷,以板带轧制塑性变形基本公式为基础,将前滑区与后滑区的单位轧制力分布做线性简化,继而推导出极限静摩擦力矩模型。并以实测数据验证该模型的准确性,且从轧制转矩与极限静摩擦力矩差值的变化趋势中发现,随着轧制公里数的增加,差值有逐渐减小到零的趋势。同时利用差值小于设定阈值的方式来判定工作辊是否发生打滑,并应用于现场在线打滑预警系统中。实践证明,该模型对冷连轧工作辊打滑判定具有重要意义。     

具有伸长率分配计算功能的轧制力预报智能模型研究

针对双机架平整机的特性,以基态弯辊力下带材出口板形最好为准则,提出具有双机架平整机伸长率分配系数计算功能的轧制力模型;在此基础上,为了改善传统轧制力模型的预报精度,提出了先通过神经网络利用在线测得的实际数据预测变形抗力和摩擦因数,再与轧制力机理模型自学习过程相结合的轧制力预报新方法;并将其应用于宝钢1220双机架平整机的生产实践,结果表明此模型可以高精度地预报轧制压力.     

二次冷轧机组乳化液体积分数在线控制技术

 针对二次冷轧机组轧制升降速过程中轧制压力波动的问题,充分考虑乳化液直喷系统的设备与工艺特点,在分析了轧制速度、乳化液体积分数等对带钢表面析出油膜厚度、轧制变形区油膜厚度、摩擦因数、前滑值、轧制压力影响的基础上,建立了乳化液体积分数与轧制速度之间的对应关系,通过在线实时调节乳化液体积分数弥补升降速过程轧制压力的波动,形成一套二次冷轧机组乳化液体积分数在线控制技术。本技术在某钢厂1 220二次冷轧机组应用后,有效地减少了升降速过程轧制压力与带钢厚度波动,提升了轧制稳定性与产品质量,具有进一步推广应用的价值。     

冷连轧升降速过程板形控制工艺润滑制度优化

 冷连轧机组在带钢升降速过程中,轧制速度会出现频繁的、较大程度的波动,轧制变形区的摩擦因数也会随之发生较大的波动,引起轧制压力来回波动,从而造成升降速阶段的板形相较平稳阶段的板形而言呈现出大幅度变差的问题。工艺制度优化对于摩擦因数引起的板形问题非常有效,因此,首先分析了不同乳化液浓度、初始温度和流量下的带钢在升降速过程中板形的变化过程。针对升降速阶段板形缺陷,采用分段离散法将带钢分别沿横向和纵向分成若干条元,提出升降速过程中板形横向目标函数和纵向目标函数,进而构造出升降速过程中板形动态变化目标函数,实现对轧制过程中板形波动在横向和纵向上的综合控制。由于乳化液浓度和初始温度在轧制过程中无法改变,所以结合板形目标函数,以带钢不发生打滑和热划伤、各机架轧制力不超过限定轧制力为约束条件,提出乳化液浓度和初始温度优化设定函数;乳化液流量优化针对频繁变化的局部浪形缺陷能够起到有效控制,因此乳化液流量一般随轧制速度呈非线性变化,以出口板形波动最小为控制函数,以不发生打滑和热划伤、各机架乳化液总量不超限为约束条件,提出乳化液流量跟随速度优化函数。最后将优化模型应用于国内某钢厂冷连轧机组,根据优化前后轧制力分布、带钢板形云图可知现场应用效果良好。     

Optimization of Temperature and Force Adaptation Algorithm in Hot Strip Mill

Abstract： In the hot strip rolling control system, the temperature distribution and deformation resistance are the main parameters affecting prediction of rolling force. In order to improve the model prediction precision, an optimiza- tion algorithm based on objective function was put forward, in which the penalty function index was adopted. During the adaptation process, the temperature distribution and deformation resistance were taken as the optimized parame ters, and the Nelder-Mead simplex algorithm was used to search the optimal solution of the objective function. Fur thermore, the temperature adaptation and force adaptation were solved simultaneously. Application results show that the method can improve the accuracy of the rolling force model obviously, and it can meet the demand of the indus trial production and has a good application prospect.     

三辊定减径机轧后钢管弯曲的原因分析

无缝钢管经过三辊定减径机轧制生产工序后,有时会产生弯曲,影响产品质量和深加工.通过研究管材纵轧变形机理,从摩擦系数、变形抗力和前滑等几个方面分析了轧辊辊径、轧辊硬度、轧件温度的变化对三辊定减径机轧后钢管弯曲产生的影响.     

Analysis of Hot Tandem Rolling Force with Logarithmic Velocity Field and EA Yield Criterion

In order to analyze the hot tandem roiling force, a new logarithmic velocity field is proposed. Using the field and linear EA （equal area） yield criterion, the plastic deformation power for plate rolling is analyzed, and the friction power is obtained based on the co-line vector inner product method. Then analytical solution of plate rolling power functional is obtained. Finally, by minimizing the power functional, the rolling torce and torque are received. Compared with those measured ones in hot tandem rolling on-line, the calculated rolling forces are in good agreement with the actual measured ones since the maximum error is less than 12~. Moreover, the effects of various rolling conditions such as thickness reduction, friction factor and shape factor, upon separating force, location of neutral an- gle, and stress state coefficient are discussed systematically.     

粗轧过程中轧制力和宽展的预测与分析

 板带轧制数学模型是实现自动控制的基础,高精度的数学模型是提升产品质量和市场竞争力的重要保障。在热连轧粗轧过程控制中,轧制力和宽展是关键参数,其模型精度不仅会影响粗轧轧制规程的设定,而且会影响最终热连轧带钢产品凸度。以矩形板坯热连轧粗轧过程为研究对象,针对轧制变形区建立了三维运动许可加权速度场,在此基础上充分考虑自然宽展效应,基于刚塑性材料的第一变分原理,采用可变上限积分法对塑性变形、剪切功率和摩擦功率进行积分获得变形区总功率泛函。利用Matlab优化工具箱对总功率泛函进行最小化,得到了轧制力、宽度分布的理论解。最后利用理论模型计算数据回归得到了板坯宽展及速度场中的加权系数模型。将基于所提出模型的轧制力和宽展预测值与现场实测值及部分有关学者所建立模型的预测值进行了对比,结果验证了所建立模型的准确性。研究得到的宽展模型和速度场加权系数表达式可以方便、灵活、快速地应用到粗轧现场中,为更高质量热连轧带钢产品的生产奠定了坚实基础。     

Friction Estimation and Roll Force Prediction during Hot Strip Rolling

A mathematical model of friction coefficient was proposed for the roll force calculation of hot-rolled strips. The online numerical solving method of the roll force calculation formula based on the proposed friction model was developed and illustrated by the practical calculation case.Then,the friction coefficient during hot strip rolling was estimated from the measured roll force by force model inversion.And then,the expression of friction model was pro-posed by analyzing the calculation process of stress state coefficient,and the model parameters were determined by the shared parameter multi-model nonlinear optimization method.Finally,the industrial experiments demonstrated the feasibility and effectiveness of the related models.The accuracy of the new roll force model based on the built friction model was much higher than that of the traditional Sims model,and it could be applied in the online hot roll-ing process control.     

超高强钢冷轧过程轧制力计算的改进模型

 为了解决采用圆弧模型计算超高强钢冷轧过程轧制变形区轧辊压扁曲线误差较大的问题,充分考虑到超高强钢的轧制特点,通过分析不同压扁半径下轧辊压扁曲线的变化规律,构造出新型轧辊压扁曲线函数模型,给出了该函数中轧制变形区接触弧长特性参数与轧辊压扁曲线特性参数的求解方法。基于此,根据弹塑性理论中的变形与应力关系,推导了入口弹性变形区、塑性压下变形区以及出口弹性变形区单位轧制压力分布计算过程,建立了超高强钢冷轧过程总轧制力计算模型。并将其推广应用到某钢厂2030冷连轧机组,验证了该模型的计算准确度。结果表明,超高强钢冷轧过程轧辊压扁曲线用二次函数表示,更能准确反映轧辊压扁状态,其计算结果与实际值具有较高的吻合度。同时,为冷连轧机组生产超高强钢产品极限轧制能力的评估与轧制规程的制定提供了理论依据。