Analysis of CVC roll contour and determination of roll crown

Mathematical analysis of continuous variable crown （CVC） roll contour used in CSP production line was conducted and the roll contour function of CVC roll was obtained. The validation with actual CVC roll contour shows that the calculation values of the roll contour function and the actual roll contour parameters given by equipment provider are the same, which proves that the roll contour function of CVC rolls given in this article is correct. The nonlinear relationship between the roll crown of CVC rolls and roll shift amounts was deduced. The concept of crown extremum was given.

Control of thermal crown in the roller inside the continuous annealing furnace

In a continuous annealing furnace, the hearth rollers are affected by heat, which in turn affects the stable operation of the steel strips. In order to ensure the stable operation of the steel strips the ability of the rollers to correct themselves and to prevent the steel strips from buckling, effective measures are required to control the surface crown of the rollers inside the furnace. Starting from production, this study analyzes the way in which the crown of the hearth rollers inside the continuous annealing furnace changes. The study suggests control measures to prevent buckling and and misalignment. The study definitely provides guidance to the stable operation of steel strips in continuous annealed furnaces.

Analysis of Temperature Field and Thermal Crown of Roll During Hot Rolling by Simplified FEM

Thermal crown of roll is an important factor, which affects strip profile. It is necessary to analyze the temperature field and thermal crown of roll for hot strip mill. A new simplified finite element method （FEM） was used to analyze the temperature field and thermal crown of roll, and corresponding models were built according to the practical boundary conditions. Transient roll temperature field and thermal crown were simulated by ANSYS FEM software with considering transient thermal contact and complex boundary condition. Temperature and thermal crown variations on roll surface nodes were obtained. The thermal crown results of roll obtained by FEM simulation were in good agreement with the measured data, indicating that simplified FEM models and results were correct.

Study and application of crown feedback control in hot strip rolling

Crown feedback control is one part of the automatic shape control （ASC） system. On the basis of large simulation researches conducted, a linear crown feedback control model was put forward and applied in actual strip rolling. According to its successful op- eration in the ASP 1700 hot strip mill of Angang Group for one year and also from the statistical results of several crown measurements, it can be definitely said that this control model is highly effective and shows stable performance. The control effectiveness of different gauges of strips with the feedback control is found to increase by 10%-30% compared with that without feedback control.

Application of Crown-Flatness Vector Analysis in Plate Rolling Schedule

A simple plate crown model was introduced,and the crown-flatness vector analysis method was analyzed.Based on the plate rolling technology,the rolling schedule design of elongation phase is divided into three steps.First step is to calculate the reductions of first pass of elongation making full use of the mill capability to decrease the total pass number.The second step is to calculate the pass reduction for the last three or four passes to control crown and flatness by crown-flatness vector analysis method.In the third step,the maximum rolling force limit and the total pass number are adjusted to make the plate gauge at exit equal to target gauge with satisfactory flatness.The on-line application shows that this method is effective.

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 roiling 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 roils 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-13 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.

Mechanical Analysis of Dead Load Crown and Structure Parameter of Hydraulic Elastic Bulging Roll

The dead load crown of hydraulic elastic bulging roll was discussed using the theory of elastically supported beam,and the dead load experiment was carried out. The theoretical calculation is consistent with the experimental result. The structure parameters for the thickness of roll sleeve,the length of the oil groove and the crown of roll were discussed. The fundamental principle of determining the parameters was put forward. The theoretical basis of the application of the hydraulic elastic bulging roll was established.

Analysis of the change of roll thermal crown in 1750 mm hot strip mill

Studied the distributing of roll temperature and the change rule of thermal crown in 1 750 hot strip mill,the result of the test showed that the change of roll thermal crown was affected by the condition of roll cooling and equipmentthe roll thermal crown was obviously improved after altering the pipe and water nib of cooling equipment.From the rule of roll thermal crown changing with the number of strip rolling know that the thermal crown of work roll of Standi is the largest,and Stand 6 is the smallest one in a period of rolling.

Roll Gap Crown Adjustment Characteristics of 1700 mm Cold Rolling Mills

The 4-hi cold mill is one of the key wide strip tandem cold rolling mills and has many advantages and characteristics. The mill type is the most important, fundamental and long-term effective factor for the strip shape control. Many advanced mill types such as CVC-4, HCW and PC-4, etc are created based on the conventional four-roll mill. The factors of mill type which affect the deformation of roll system, such as strip width, rolling force, bending force, work roll diameter, backup diameter and so on, arc studied how to affect roll gap crown. It provides a good foundation lbr improving the shape performance of mill.

Effect of Load Distribution on Strip Crown in Hot Strip Rolling

In order to establish precision model, a software to calculate the strip crown of four-high hot rolling mill was developedby using affecting function method according to the strip crown calculation theory. The effect of work roll diameter,unit width rolling load, roll bending force, work roll crown, initial strip crown and reduction, etc, on load distributioneffect rate was simulated by using the software. The results show that the load distribution effect rate increaseswith the increase of strip width, work roll diameter, unit width rolling load, roll bending force, work roll crown,initial strip crown and reduction. Based on the simulation results, base value of load distribution effect rate andfitting coefficients of six power polynomial of load distribution effect rate modification coefficient were determinedconsidering all of the above parameters. A simplified mathematical model for calculating load distribution effect ratewas established.

一种基于五次CVC和SmartCrown复合辊型的板形控制方法

为改善轧机的板形调控能力,在分析连续变凸度CVC辊型和SmartCrown辊型特性的基础上,提出了一种基于五次CVC和SmartCrown的复合辊型的板形控制方法。将五次CVC和SmartCrown辊型在控制板形缺陷方面的特性相结合,采用分解与迭加的方法重新确定其二次和四次凸度及调控能力。通过设计实例和效果分析验证,表明该方法有效改善了五次CVC和AVC辊型因辊径差较大不利于板形控制的缺点。

基于核偏最小二乘法的热轧板凸度预测

以某2160 mm热连轧生产线为研究对象,结合生产数据和数据驱动算法,提出并建立基于核偏最小二乘法和偏最小二乘法的热轧板凸度预测模型,并对模型的参数进行调整和优化。结果表明:偏最小二乘法模型的预测值与实测值误差为-25~30μm,88.74%的板凸度预测值绝对误差小于10μm;核偏最小二乘法模型的预测值与实测值误差为-25~25μm,91.57%的板凸度预测值绝对误差小于10μm。因此,优化后的核偏最小二乘法模型具有更好的预测效果。

圆锥滚子圆弧凸度无心贯穿式包络法磨削

为提高圆锥滚子凸度磨削精度,提出一种圆锥滚子凸度无心贯穿式包络法磨削方法,将砂轮修整为凸圆弧廓形,将导轮修磨成其半径按凹曲线变化,使滚子在曲线轨迹贯穿过程中凸度曲线始终与砂轮圆弧廓形相切,从而实现滚子凸度形状的包络法磨削成形。并针对单一圆弧滚子凸度,阐述了滚子凸度包络法磨削的原理和优点,给出了砂轮廓形圆弧半径和导轮轴向廓形(导轮半径变化曲线和导轮形面轴向截形角)的计算方法。

面向热轧辊磨损的变凸度调节自适应辊形设计

为了提高热轧辊辊形凸度控制能力,提出了一种面向轧辊磨损和凸度调节的自适应辊形设计方法。选择常规CVC辊形来实现离散处理,利用遗传算法优异搜索能力给出了具体处理步骤。研究结果表明:CVC辊形总共产生了327.64mm的磨损程度,自适应辊形产生了302.29mm的磨损程度,自适应辊形磨损程度相对CVC辊形更小。该研究有助于提高轧制精度,具有较好的实用价值。

基于混合多阶集成模型的非平衡热轧带钢凸度智能诊断

为了提升带钢热轧加工过程的智能化水平,基于数字孪生(DT)和信息物理系统(CPS),文本采用数据驱动方法以诊断热轧带钢凸度。因为热轧工艺具有遗传性、非线性和强耦合性的特点,因此带钢凸度诊断是一个决策边界不明确的非平衡问题。现有回归方法倾向于从多数类样本学习信息,而忽略了少数类的缺陷凸度。为了解决这一问题,本文提出了一个混合多阶集成模型(HMSEN)分类带钢凸度。首先,提出了一个新的采样方法,该方法结合了自适应采样(ADASYN)和重复编辑近邻样本(RENN)以强化对缺陷凸度的关注。随后,基于增加的数据,建立了一个多阶集成模型以提升分类精度。同时,通过分析不同基分类器的组合确定了最佳性能的混合多阶集成模型。实验结果表明,相比于其它采样方法,本文提出的采样方法更适合凸度数据集。此外,混合多阶集成模型的性能要优于现有回归方法和机理模型。因此,对于非平衡热轧带钢凸度智能诊断,本文提出的混合多阶集成模型是一种有效且鲁棒的方法。

热轧薄规格带钢板凸度纵向分布特征的研究

为了控制某1780 mm热轧生产线薄带钢板凸度的纵向分布,通过分析现场轧制过程工艺及板凸度数据,对影响因素进行了定量分析。结果表明:随着带钢厚度的减小,带钢板凸度纵向差值越大,其带钢长度方向上F7机架出口温度、速度和F1机架轧制压力和弯辊力差值越大。随着带钢宽度的减小,板凸度纵向衰减量逐渐增大,带钢中后部的板凸度逐渐低于目标值的下限。随精轧F7机架出口速度、温度的升高以及F1机架轧制压力和弯辊力的降低,板凸度发生衰减,且上述轧制参数波动值越大衰减特征越明显、衰减量越大。

STUDY OF ROLLING FORCE DISTRIBUTION ALONG THE ROLLING OF PAIR CROSS MILL

The theory of three-dimensional deformation is used.Based on rigid plastic assumption, the theory of stick friction and the sheet crown curve at the entry and the exit are used. The mathematical analytical formula of the rolling force in lateral distribution is deriven.

Smart Crown技术的研究与应用

介绍了Smart Crown板形控制技术的原理及技术特点,根据Smart Crown辊型曲线方程推导了轧辊等效凸度方程。生产实践证明,使用Smart Crown工作辊后,轧机板形控制能力显著提高,轧辊磨损均匀,工作周期显著延长。

Analysis of the thermal profile of work rolls in the hot strip rolling process

A 2-dimension axisymmetric model was developed by the finite-differencemethod, which can be used to predict the transient temperature field and thermal profile of workrolls in the hot strip rolling process. To demonstrate the accuracy and reliability of the solutiondeveloped, the calculation results were compared with the production data of a 1700 mm hot striprolling mill and good agreement was found between them. The effect of strip width and roll shiftingon the thermal expansion of the work rolls was studied. It is found that the strip width has markedeffect on the efficient thermal crown. Initially, when the rolling strip changes from narrow towide, a bigger efficient thermal crown can be quickly achieved; afterwards, when the rolling stripchanges from wide to narrow, not only the influence of uneven wear can be reduced but also theexcessive efficient thermal crown can be avoided. It is also found that the work roll shifting has adeterminate but not obvious effect on the reduction of the efficient thermal crown, and will makethe strip shape unstable without being used properly.

Application of Shape Lock-on Method in Plate Rolling

AGC system can improve the plate gauge precision,and damage the plate shape if the shape control loop is left quite open.This damage will cause wave during rolling wide-thin plate.A control strategy named shape lock-on method is afforded for plate shape control.This method requires APC instead of AGC at last one or two passes during rolling wide-thin plate.Approved by theory and on-line application,this method is good for the plate shape and crown control with small effect on gauge control.