Research and Development Trend of Shape Control for Cold Rolling Strip

Shape is an important quality index of cold rolling strip. Up to now, many problems in the shape control domain have not been solved satisfactorily, and a review on the research progress in the shape control domain can help to seek new breakthrough directions. In the past 10 years, researches and applications of shape control models, shape control means, shape detection technology, and shape con- trol system have achieved significant progress. In the aspect of shape control models, the researches in the past improve the accuracy, speed and robustness of the models. The intelligentization of shape control models should be strengthened in the future. In the aspect of the shape control means, the researches in the past focus on the roll opti- mization, mill type selection, process optimization, local strip shape control, edge drop control, and so on. In the future, more attention should be paid to the coordination control of both strip shape and other quality indexes, and the refinement of control objective should be strengthened. In the aspects of shape detection technology and shape control system, some new types of shape detection meters and shape control systems are developed and have successfully indus- trial applications. In the future, the standardization of shape detection technology and shape control system should be promoted to solve the problem of compatibility. In general,the four expected development trends of shape control for cold roiling strip in the future are intelligentization, coordi- nation, refinement, and standardization. The proposed research provides new breakthrough directions for improv- ing shape quality.

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 a1700 mm single-stand temper mill. Some critical problems such as the deviation of work roll contourcaused by grinding and wear, the effectiveness of work roll bending were discussed. Using a finiteelement 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 somespecial features of flatness control in the temper mill: during temper rolling, roll deformation isslight due to small rolling load, and the loaded roll gap profile mainly depends on work rollcontour, while the backup roll has a little effect on gap crown; the effect of bending force ongauge can not be ignored due to the coupling between flatness control and gauge control. A new rollcontour 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 workroll bender, higher rolling stability, better strip profile and flatness quality.

Industrial shape detecting system of cold rolling strip

A high-precision shape detecting system of cold rolling strip is developed to meet industrial application,which mainly consists of the shape detecting roller,the collecting ring,the digital signal processing(DSP) shape signal processing board and the shape control model.Based on the shape detecting principle,the shape detecting roller is designed with a new integral structure for improving the precision of shape detecting and avoiding scratching strip surface.Based on the DSP technology,the DSP shape signal processing circuit board is designed and embedded in the shape detecting system for the reliability and stability of shape signal processing.The shape detecting system was successfully used in Angang 1 250 mm HC 6-high reversible cold rolling mill.The precision of shape detecting is 0.2 I and the shape deviation is controlled within 6 I after the close loop shape control is input.

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.

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.

Control Strategies of Asymmetric Strip Shape in Six-High Cold Rolling Mill

It is a complicated problem for cold-rolled strip to improve asymmetric strip shape in strip production. A roll system and strip coupled model of six-high cold rolling mill was established with finite element method to estimate the effect of intermediate roll shifting, tilting, symmetric and asymmetric bending technologies on strip profile. To reduce asymmetric defects of strip shape as much as possible, some control strategies were proposed, including tilting and asymmetric bending of intermediate roll and work roll. The combinations of these three control strategies can effectively eliminate asymmetric strip shape defects. Finally, the closed-loop control model of asymmetric flat- ness at the last stand was given, and the flatness control system with the function of asymmetric strip shape control was also designed for cold tandem mill.

Backup roll contour of a SmartCrown tandem cold rolling mill

SmartCrown was a new system developed by VAI for improving the strip profile and flatness control first applied in 1700 mm tandem cold rolling mills at Wuhan Iron ＆ Steel （Group） Corporation （WISCO）. After tracing and testing, the application of the conventional crown backup roll matching the SmartCrown work roll of the production mill led to heavy and nonuniform wear, and the edge spalling of the backup roll often occurred. A 3-dimension finite element model of roll stacks was established, which was used to analyze the above-mentioned problems, and it was found that the main reason was the highly nonuniform contact pressure distribution between the work roll and the backup roll. A new FSR （flexible shape backup roll） was developed and applied in 1700 mm tandem cold rolling mills. A lot of good actual effects of FSR, such as evident improvement in profile and flatness of strips, non-occurring edge spalling, wear uniform, and remarkable decrease in roll consumption were validated by long-term industrial applications.

基于改进斑点鬣狗算法的热轧带钢负荷分配智能优化

针对热连轧过程中由于负荷分配不均匀导致板形控制效果不佳的问题,以传统的轧制机理为基础建立负荷分配均匀、板形良好的目标函数,分别采用斑点鬣狗算法和改进斑点鬣狗算法进行单目标和双目标的负荷分配的优化求解。结果表明,改进斑点鬣狗算法将末机架的相对凸度差从0.000 834 5降低到0.000 014 83和-0.000 026 34,且在允许的范围内,上游机架负荷分配合理,充分发挥了轧机的轧制能力。

CSP产线工作辊辊形优化及智能窜辊策略研究

对热轧CSP产线生产的硅钢板带断面进行测量发现,在工作辊服役后期生产的产品,其断面常出现局部高点现象。服役后下机工作辊轮廓也在对应带钢断面局部高点位置,呈现“猫耳”型磨损。对F7工作辊辊形进行了优化,并考虑机组设备现有的工作辊窜辊功能,使用变行程、步长的智能窜辊策略,通过改善工作辊磨损状态,均匀轧辊磨损,延长轧制公里数,改善硅钢板带断面的局部高点。该优化方案自上线以来,有效保证整个工作辊服役周期内具有良好的凸度控制能力,断面质量控制稳定性与轧制公里数大幅度提升。

冷轧平整机板形控制研究

对某厂冷轧平整机的轧制生产过程进行分析,利用有限元仿真模型技术对板形特征调控进行仿真分析,深入研究平整机辊形、轧制力以及生产带钢宽度对生产带钢板形的影响,由仿真模型结果展现出板形问题的机理,以此为基础提出冷轧平整机板形控制措施。通过实际应用对比发现,改进后,带钢生产时板形问题出现概率降低59%。

热带钢轧机板形综合控制技术开发

为了改善热带钢轧机的板形控制性能、提高产品的板形质量、降低生产消耗,针对工作辊可轴向窜动的热带钢轧机,在大量有限元模拟基础上开发了特殊的工作辊辊形技术和支持辊辊形技术及相应的板形控制模型,包括过程控制系统(L2级)的板形设定控制模型和基础自动化系统(L1级)的弯辊力前馈控制模型、凸度反馈控制模型及平坦度反馈控制模型.在经历离线模型建立、在线编程和调试等诸多复杂过程后,辊形技术及板形控制模型在工业宽带钢热轧机上进行了长期、稳定的应用.生产实践表明,采用这些板形控制技术后,凸度偏差控制在±18μm的比例超过93%,平坦度偏差控制在±25IU的比例超过94%,同时实现了自由规程轧制.

UCM六辊冷轧机中间辊辊形研究

针对1500UCM宽带钢冷轧机轧制薄规格带钢易出现板形缺陷和轧辊剥落等问题,采用有限元软件ANSYS建立六辊轧机辊系弹性变形三维有限元模型,并利用UCM轧机窜辊特性和轧机板形控制性能指标设计中间辊新辊形。有限元仿真研究表明:UCM轧机中间辊新辊形与原辊形相比,轧机板形控制能力明显提高,工作辊弯辊调控功效提高35.21%,辊缝横向刚度增强12.25%,常轧宽度1 280 mm薄板的辊缝凸度调节域面积增大75.26%;且UCM轧机辊间压力分布得到改善,中间辊和工作辊的辊间接触压力峰值和辊间接触压力不均匀度系数分别下降3.16%和2.53%,支持辊和中间辊辊间接触压力峰值和辊间接触压力不均匀度系数分别下降13.29%和17.45%。研究结果为开展UCM轧机中间辊新辊形工业实验提供了理论依据。

板形控制与热轧带钢自由规程轧制

板形是热轧带钢的重要质量指标。自由规程轧制是带钢热轧中实现柔性生产组织和最高生产效率的必由之路。热轧工作辊表面严重不均匀磨损 ,导致承载辊缝形状畸变和“批量同宽轧制”或“大逆宽轧制”时带钢板形失控 ,进而制约了自由规程轧制。自由规程轧制问题本质上是板形控制问题。为了实现自由规程轧制需减少磨损量、均匀化磨损分布或开发特殊的板形控制技术。

冷连轧机带钢单锥度辊边降控制

针对冷连轧机带钢边降板形控制问题,研究了单锥度工作辊的辊形构成、特点和控制策略,建立有限元模型对比分析了单锥度、常规凸度和SmartCrown工作辊板形控制性能,并结合大型工业轧机调试实验分析了该板形控制新技术在实际生产中的使用情况.结果表明,应用单锥度辊可以有效降低带钢边降,减小带钢总凸度.

冷轧平整机板形问题的特点及对策

对某冷轧厂 170 0 m m单机架平整机的板形问题进行了综合研究 ,发现该轧机在辊形加工、轧辊磨损及弯辊使用等方面存在的问题 ,并通过有限元模型研究了辊形对板形的作用 ,分析了平整上弯辊对板厚的影响 ,指出平整机板形问题的特殊性。针对平整板形的设备工艺特点 ,提出了新的辊形配置方案并正式投入生产。结果表明 ,改进后的辊形配置对降低弯辊调整量、改善板形、提高生产过程稳定性效果显著。

济钢1700mm热带钢轧机的板形设定控制模型

济钢1700 mm热连轧是新建投产的宽带钢生产线,其F2—F6精轧机组装备有工作辊弯辊和窜辊技术。针对这种典型机型,在大量有限元模拟计算的基础上,开发了相应的板形设定控制模型,包括工作辊综合辊形(初始辊形、磨损辊形和热辊形之和)计算模型、支承辊综合辊形计算模型、窜辊设定计算模型和弯辊力设定计算模型等。在经历了系统设计、程序编写、离线调试、在线调试后,板形设定控制模型投入稳定运行,所有考核规格的凸度控制精度超过96%。在同宽轧制长度超过70 km的轧制单位内,各机架弯辊力设定结果能够自动适应带钢厚度和钢种的变化,且凸度控制精度超过95%。

宽带钢轧机板形控制技术比较研究

运用软件仿真方法并结合生产实践，从板形调控功效和板带轧机综合性能两个方面，比较研究了目前国际上各主要板形控制技术．研究结果不仅有助于板带轧机的选型和板形技术的配置，也有益于先进板形技术的创制．

轴向移位变凸度四辊轧机的辊型设计

板材轧机上一对带特殊辊型的工作辊轴向相对移动时，可改变辊缝凸度，调节板形。通过对这类辊型的研究，特别是对三次辊型的研究和ＣＶＣ辊型的破译，给出了确定辊型参数的方法，并指出了ＣＶＣ辊型和ＵＰＣ辊型的区别及应用范围。

冷轧带钢在线板形信号补偿技术及工业应用

综合考虑冷带钢轧机现场实际工况条件,根据板形仪在线板形检测原理、受力条件和几何关系,研究带钢横向温差、带钢卷形、边部覆盖,检测辊包角、挠度、安装几何误差和磨损量等因素对在线板形检测精度的影响,与生产实际相结合,建立一套满足工业应用的在线板形信号综合补偿模型。依托该模型开发的在线板形信号综合补偿技术,成功应用于鞍钢1 250 mm六辊冷带钢轧机上,使板形仪在线检测板形信号准确反映冷轧带钢真实板形状况,兼顾后续深加工工艺要求,根据不同轧制条件和产品规格制定动态板形标准曲线,为板形闭环控制提供可靠板形数据,显著提高冷轧带钢产品的板形指标和质量稳定性。总张力计算值与实测值误差在3%以内,板形闭环控制投入后,稳态时板形指标在6 I以内。

冷连轧机变接触支承辊板形控制性能研究与应用

通过现场跟踪测试和生产实践发现武钢1700冷连轧机组“酸轧联机”改造工程中存在常规凸度辊形配置方案不合理,由此引起了薄规格轧制的工作辊“压肩”现象和轧制过程欠稳定导致成品板形质量欠佳等问题。采用二维变厚度有限元方法建立辊系弹性变形仿真模型,研制了酸轧联机条件下的VCR变接触支承辊,经过工业轧机现场轧制已成功投入1700冷连轧机实际应用。现场应用表明:改善了轧机板形调控性能,提高了带钢板形质量,增强了薄规格品种轧制能力,支承辊辊形自保持性较好。