Roll shifting strategy with varying stroke and step in hot strip mill

A new roll shifting strategy with varying stroke and varying step was investigated. Two characteristic parameters including cat ear height and gap contour smoothness were introduced to assess the effect of shifting strategy on roll wear, and the relation between characteristic parameters and shifting strategy was established. Both varying stroke and varying step can reduce cat ear height and gap contour smoothness, so the shifting strategy with varying stroke and varying step is better than the one with either varying stroke or varying step. Based on the effect of shifting control parameters on characteristic parameters of roll wear, the selection principle of these shifting control parameters was gained. A case study was conducted to validate the proposed roll shifting strategy, reducing uncontrollable quartic loading gap contour, improving strip profile and extending rolling length of a rolling campaign.     

Backup roll contour in finishing trains of hot rolling based on hybrid genetic algorithm

On the basis of integrating two-dimensional varying thickness finite element method with hybrid genetic algorthm,a precise model was developed to design ideal backup roll contour(Varying Contact Backup Roll,inshort VCR) in finishing trains of hot rolling rapidly and efficaciously,Additionally,a lot of good actual effects of VCR,such as evident improvement of profile and flatness of strip,remarkable decrease of roll consume,excellent maneuverability and maintenance,and so on,were validated by long-tem industrial tests in hot rolling strip plant of Wuhan Iron and Steel Group Corporation(WISCO).     

WRS轧机工作辊磨损计算及板形调控分析

在热带钢连轧机设计及改造中采用WRS辊系作为下游机座可以增强机组的板形调控能力。从理论上分析了辊系在轧制中的磨损特性，工作辊磨损辊型的计算方法，根据实际轧制工况对其板形的调控、影响因素进行了定量分析。     

VCR and ASR technology for profile and flatness control in hot strip mills

The roll contour pattern and variety of work and backup rolls in service and its effect on profile and flatness control performance in 1 700 mm hot strip mill at Wuhan Iron and Steel （Group） Corporation were tested and analyzed by the developed finite element models of different typical roll contours configurations. A rather smooth local work roll contour near strip edges and an increase in rolled length can be obtained by application of long stroke work roll shifting system with conventional work roll contours that is incapable of the crown control. In comparison with the conventional backup and work roll contours configuration, the crown control range by the roll bending force enhances by 12.79% and the roll gap stiffness increases by 25.26% with the developed asymmetry self-compensating work rolls（ASR） and varying contact backup rolls（VCR）. A better strip profile and flatness quality, an increase in coil numbers within the rolling campaign and a significant alleviated effect of severe work roll wear contours on performance of edge drop control are achieved by the application of ASR with crown control and wear control ability in downstream stand F5 and VCR in all stands of 1 700 mm hot strip mill.     

Improvement on strip flatness of cold temper mills by modifying roll contour shape

A study on roll gap profile (strip profile) control was accomplished in a 1700 mm single-stand temper mill. Some critical problems such as the deviation of work roll contour caused by grinding and wear, the effectiveness of work roll bending were discussed. Using a finite element model, the effects of roll contours (ground and wear) on strip profile were investigated. The roll bending effect on strip thickness was also analyzed. It is pointed out that there are some special features of flatness control in the temper mill: during temper rolling, roll deformation is slight due to small rolling load, and the loaded roll gap profile mainly depends on work roll contour, while the backup roll has a little effect on gap crown; the effect of bending force on gauge can not be ignored due to the coupling between flatness control and gauge control. A new roll contour arrangement adaptable to the mill was presented and has been put into practical production. The application of the new set of rolls showed some good results: larger crown control range of work roll bender, higher rolling stability, better strip profile and flatness quality.     

Strip shape control capability of hot wide strip rolling mills

The elasticity deformation of rolls was analyzed by means of two-dimensional finite element method （FEM） with variable thickness. Three typical mills were used as objects for analysis. A thorough study was done on the control capabilities of these mills on the strip shape. Then the strip shape control capabilities of the three mills was compared synthetically. 2008 University of Science and Technology Beijing. All rights reserved.     

精轧张力系统的仿真与试验

针对传统的活套控制中带钢张力及活套角度波动问题,提出了张力加权控制和状态反馈控制方法。张力加权控制是将恒张力和恒力矩控制结合在一起,活套电流的给定值为两者的加权。采用张力加权控制后,带钢张力和活套角度波动减少。试验证明该方法能够在不改变现有硬件设备的条件下改善精轧张力控制系统的控制性能。状态反馈控制采用状态反馈加输入变换的策略,可实现活套角度和机架间张力的解耦,获得更加理想的系统控制性能。     

热轧带钢终轧温度控制模型的应用研究

为了适应加速轧制时高精度终轧温度控制的要求,在机架间冷却单元的基础上开发了在线自适应、前馈与反馈相结合的在线终轧温度控制模型,并现场测试了机架间冷却阀门的开度和流量曲线。结果表明,该模型对于提高终轧温度控制精度是有效的。     

精轧张力系统的仿真与试验

针对传统的活套控制中带钢张力及活套角度波动问题,提出了张力加权控制和状态反馈控制方法。张力加权控制是将恒张力和恒力矩控制结合在一起,活套电流的给定值为两者的加权。采用张力加权控制后,带钢张力和活套角度波动减少。试验证明该方法能够在不改变现有硬件设备的条件下改善精轧张力控制系统的控制性能。状态反馈控制采用状态反馈加输入变换的策略,可实现活套角度和机架间张力的解耦,获得更加理想的系统控制性能。     

Comprehensive contour prediction model of work rolls in hot wide strip mill

The predictive calculation of comprehensive contour of work rolls in the on-line strip shape control model during hot rolling consists of two important parts of wear contour calculation and thermal contour calculation, which have a direct influence on the ac- curacy of shape control. A statistical wear model and a finite difference thermal contour model of work rolls were described. The comprehensive contour is the equivalence treatment of the sum of grinding, wear, and thermal contours. This comprehensive contour calculation model has been applied successfully in the real on-line strip shape control model. Its high precision has been proved through the large amounts of actual roll profile measurements and theoretical analyses. The hit rates (percent of shape index satisfying re- quirement) of crown and head flatness of the strips rolled, by using the shape control model, which includes the comprehensive contour calculation model, have about 16% and 10% increase respectively, compared to those of strips rolled by using manual operation.     

Work roll thermal contour prediction model of nonoriented electrical steel sheets in hot strip mills

The demands for profile and flatness of nonoriented electrical steels are becoming more and more severe. The temperature field and thermal contour of work rolls are the key factors that affect the profile and flatness control in the finishing trains of the hot rolling. A theoretic mathematical model was built by a two-dimensional finite difference to calculate the temperature field and thermal contour at any time within the entire rolling campaign in the hot rolling process. To improve the calculating speed and precision, some special solutions were introduced, including the development of this model, the simplification of boundary conditions, the computation of heat transfer coefficient, and the narrower mesh along the edge of the strip. The effects of rolling pace and work roll shifting on the temperature field and thermal contour of work rolls in the hot rolling process were demonstrated. The calculated results of the prediction model are in good agreement with the measured ones and can be applied to guiding profile and flatness control of nonoriented electrical steel sheets in hot strip mills.     

热连轧精轧宽度控制技术的研究及应用

在热轧带钢其他尺寸精度普遍较高的情况下,宽度控制精度的提升变得越来越重要。提出了一种新的精轧带钢宽度控制综合解决方案：针对带钢头部宽度控制,开发精轧机架冲击速降自学习模型,以减少带钢头部拉窄现象;通过合理配置精轧活套张力稳定因子,减少带钢中部宽度波动现象;通过精轧宽度反馈控制和宽展预测模型修正功能,提高带钢全长宽度精度。相关研究成果已成功应用于宝钢集团某热轧产线三电自主集成改造项目中,改造后带钢宽度控制精度得到显著提高。     

基于机理与数据驱动的热连轧板凸度组合预测

针对传统热连轧出口板凸度预测方法存在的模型精度低、解释性差等缺陷,提出了一种将机理与数据驱动相结合的热连轧板凸度组合预测模型。通过热连轧板凸度机理预测模型得到热连轧板凸度基准值,将该基准值与实际值之间的偏差量作为机器学习模型的预测变量,再将偏差量预测值与基准值进行求和得出组合预测模型的板凸度预测值,并将该组合预测策略应用至多个神经网络进行方法验证。研究结果表明,提出的热连轧板凸度组合预测模型相较于传统预测模型具有更好的预测性能,其中有97%以上预测数据的绝对误差小于0.02 mm,82%以上预测数据的绝对误差小于0.01 mm,同时该组合预测方法具有较好的可行性与普适性,所提出的模型能够实现机理模型与数据驱动模型的优势互补,使得模型更加符合实际物理意义,该组合模型既缓解了神经网络预测结果由于过程黑箱导致解释性差、可信度低的问题,又弥补了机理模型预测结果偏离生产工况、无法实时修正的缺陷,对热连轧板带钢的板形控制以及热连轧产品质量的改善具有重要意义。     

VC辊平整机板形调控性能的研究

以某厂连续退火平整机为研究对象,利用ANSYS有限元软件建立VC辊系静力学仿真模型,并研究了弯辊力、VC辊油压、轧辊辊径和辊套厚度对连续退火平整机板形控制能力的影响。结果表明,无论内、外弯辊如何配合,都不能达到只改变四次凸度的目的,不可能只通过内、外弯辊的配合来消除高次浪形;外弯辊的调控功效比内弯辊增大42%;VC辊油压的调控效果主要体现在二次凸度的改变上,改变油压后对四次凸度的影响不大;当VC辊承载时,油压不能始终保持辊套向外涨,承载时辊套可能发生反弯,向芯辊内凹陷;与大辊径相比,小辊径弯辊和油压的调控效果会增加,但辊缝横向刚度会降低;辊套壁厚的减小会使VC辊油压的调控能力有所提高。     

板带钢头部翘曲的有限元分析

为了减轻轧件头部翘曲给轧制过程带来的影响,根据现场轧制工艺,采用弹塑性有限元法建立了三维非对称轧制有限元模型。利用该模型分析热轧板带钢生产过程中轧件头部翘曲的产生机理,并研究了不同轧制工艺下的辊速比、上下表面温差、不同摩擦系数对轧件头部翘曲的影响规律。结果表明,随着压下量的增大,轧件头部翘曲量的增大趋势减缓,采用不同的配辊方案（异径比）可控制其头部翘曲的现象。     

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.     

WRS轧机工作辊横移方案及辊系变形研究

WRS轧机是一种板形调控能力较强的新型轧机.分析计算了不同工况下工作辊的磨损曲线并确定了最佳横移方案,同时对给定工况下的辊系变形进行了仿真计算.     

板形控制技术探讨

介绍带钢板形控制技术，比较其特点及应用情况，总结板形控制技术及理论成果；展望板形控制技术的发展方向，为进一步促进该技术的研究提供参考。     

Thermal Behaviors of Work Roll in Finishing Trains of Hot Rolling

In order to analyze the thermal field and thermal contour of work roll in finishing trains of hot rolling in rolling process, a quasi two-dimension implicit finite difference model is developed. To improve the calculating speed and precision, some special solutions are introduced, including the development of this model, the simplification of boundary conditions and the computation of heat transfer coefficients. The results show that these solutions of thermal behaviors of work roll are very much efficient and the model can be used as an on-line profile and flatness control model of large industrial mills..