Mathematic modeling on flexible cooling system in hot strip mill简

A novel cooling system combining ultra fast cooling rigs with laminar cooling devices was investigated. Based on the different cooling mechanisms, a serial of mathematic models were established to describe the relationship between water flow and spraying pressure and the relationship between water spraying heat flux and layout of nozzles installed on the top and bottom cooling headers. Model parameters were validated by measured data. Heat transfer models including air convection model, heat radiation model and water cooling capacity model were detailedly introduced. In addition, effects on cooling capacity by water temperature and different valve patterns were also presented. Finally, the comparison results from UFC used or not have been provided with respect to temperature evolution and mechanical properties of Q235B steel grade with thickness of 7.8 mm. Since online application of the sophisticated CTC process control system based on these models, run-out table cooling control system has been running stably and reliably to produce resource-saving, low-cost steels with smaller grain size.     

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。     

热轧带钢层流冷却的离散化边部遮蔽策略研究

层流冷却会导致高强度热轧带钢板形缺陷,合理的边部遮蔽策略有助于冷却后板形改善.针对卷取温度为500℃的12 mm厚度X70管线钢热轧带钢,建立层流冷却过程的热-力-相变耦合有限元模型,对比模拟了在常规层流冷却和离散化边部遮蔽策略下冷却过程中带钢宽度上的温度场、相变和内应力分布.结果表明:在常规层流冷却过程中,带钢边部25 mm范围内会产生塑性变形,水冷后半段的前期带钢板形有边浪的趋势,后期板形有转向中浪的趋势;而层流冷却采用离散化边部遮蔽策略时,带钢宽度方向上温差显著减小,使得贝氏体转变量和残余应力沿宽度方向上分布更均匀.这种遮蔽策略有效消除了带钢边部的塑性变形,改善了冷却板形.     

热连轧带钢层流冷却过程温度场模拟

轧后冷却过程中,卷取温度对带钢最终的微观组织和力学性能有重要影响。针对带钢轧后的层流冷却过程,分别采用有限差分法和有限元法,建立了带钢厚度方向的温度场模型,并将模型计算值与实测值进行对比。结果表明,两种方法建立的模型均能较准确地反映层流冷却过程中带钢的瞬态温度分布,为进一步分析带钢的微观组织转变和力学性能提供了依据。     

热轧带钢层流冷却的步序控制

介绍了攀钢热轧带钢厂改造层流冷却中采用的一种新的设计方法——步序控制法．它是在原有的顺序控制方法上的改进，它使程序具有实现更方便、掌握更容易、可读性更强等优点．这种方法可以用来设计复杂系统的梯形图及用于各种型号的PLC．     

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。     

热轧带钢层流冷却实时报表系统实现

对热轧带钢层流冷却实时报表系统的系统构成、系统数据的自动采集、自动存储及实时报表实现进行了详细描述.实时报表系统为模型及时改进、质量实时监督、故障及时排除及新钢种冷却工艺应用提供了可靠的数据基础.     

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.     

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.     

Algorithm design and application of novel GM-AGC based on mill stretch characteristic curve简

As the spring equation is limited to the accuracy of mill stiffness and the linearity of the mill spring curve, the traditional gaugemeter automatic gauge control （GM-AGC） system based on spring equation cannot meet the requirements of practical production. In allusion to this problem, a kind of novel GM-AGC system based on mill stretch characteristic curve was proposed. The error existing in calculating strip thickness by spring equation were analyzed first. And then the mill stretch characteristic curve which could effectively eliminate the influence of mill stiffness was described. The novel GM-AGC system has been applied successfully in a hot strip mill, the application results show that the thickness control precision is improved significantly, with the novel GM-AGC system, over 98.6% of the strip thickness deviation of 3.0 mm class can be controlled within the target tolerances of ±20 μm.     

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。     

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.     

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。     

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。     

升速轧制对热轧带钢层流冷却出口温度的影响

采用传热学原理建立了层流冷却温度有限差分模型,并用现场实测数据对水冷换热系数进行了自适应修正.对德盛1 150 mm热轧带钢层流冷却过程的温度变化进行了数值模拟,建立了一套层流冷却温度仿真系统,分析和研究升速轧制时带钢在层流冷却中温度变化的趋势.结果表明,层冷出口温度受带钢的速度影响较大,在升速过程中,如果不采用集管动态喷水调节,带钢温度出现前低后高的现象,并且随着加速度的增加带钢前后温差越大.以此为依据,现场过程自动化系统L₂级硬件采用过程服务器,基础自动化系统L₁级硬件采用西门子PLC,L₂级和L₁级软件分别在C++和Step7V5.4下编程实现,并采用了带钢头尾宏跟踪和过程自动化系统采用带钢样本微跟踪的控制策略,对处于变速及高速运动中的带钢沿长度方向逐点实施控制,用动态调节的冷却集管系统来保证在速度变化期间带钢层流冷却出口温度的稳定性.     

四辊轧机电液辊缝系统变刚度建模与控制研究

针对轧机压下缸行程变化带来的变刚度问题,借助轧制区动力学关系的引入,讨论了四辊轧机辊缝控制的机电液系统数学模型和控制要点。通过仿真与实测对比,验证了模型的有效性;以全工况下系统响应特性一致为目标,通过引入位移正反馈补偿,得到了改善大范围变刚度辊缝控制系统响应的方法;实测数据表明,所述方法能满足目标要求。最后简要讨论了用于提高板厚精度的自适应模型控制方法,并给出了实例。     

攀钢热轧加热炉自动燃烧控制系统的周期计算

介绍了在攀钢1450热轧板厂两座265 t/h的步进梁式加热炉上开发应用的L1,L2两级燃烧控制系统,其中,L1级燃烧自动控制系统主要实现如何以最快的响应速度完成以温度为目标的燃烧控制;L2级燃烧自动控制技术,主要实现在线情况下,考虑不同钢坯材质、规格、不同轧制规格、不同的组织计划、不同的钢坯装入温度、不同的生产节奏下(与轧线一体控制的)的燃烧温度的设定模型技术,以数学手段计算出在各种因素影响下,加热炉各个控制段的最佳加热温度。重点阐述了加热炉自动燃烧控制模型的核心———ACC模型周期计算处理的方法。     

Compound control for speed and tension multivariable coupling system of reversible cold strip mill

To weaken the nonlinear coupling influence among the variables in the speed and tension system of reversible cold strip mill, a compound control (CC) strategy based on invariance principle was proposed...     

热轧机主传动系统疲劳设计负荷选取原则与方法

热轧机主传动系统咬钢时受到强大的冲击扭矩作用,每年的冲击次数达10^5～10^6次,因此应以咬钢时的冲击扭矩峰值载荷谱作为主传动系统的疲劳设计负荷。通过抽象简化,建立主传动系统的动力学模型并进行动力学仿真,计算出扭矩放大系数TAF。对于新设计的轧机,可按产品大纲通过理论公式计算出轧制各产品时的稳态轧制力矩;对于现有轧机,可以通过监测轧机主电动机的电流或功率来得到稳态轧制力矩载荷谱。将各稳态轧制力矩分别乘以扭矩放大系数TAF,就得到轧机咬钢时的冲击扭矩峰值载荷谱。采用累积损伤理论,再计及低于受力零件材料疲劳极限的循环应力对疲劳裂纹扩展的影响,按此进行疲劳设计,就能保证轧机主传动系统在预期寿命内安全工作。