VC轧辊板形控制的力学原理

根据实验和有限元分析结果,分析了控制压力与油腔长度对VC轧辊的静载凸度及其分布特性的影响规律,在此基础上,阐明了VC轧辊板形控制的力学原理。在以VC轧辊为支撑辊的轧机系统中,板形控制的机理是,VC轧辊的胀辊效应可以有效地减小工作辊与支撑辊之间的接触区域,在工作辊两端形成与支撑辊弯曲方向相反的弯矩。板形控制的技术关键在于选择合适的油腔长度,消除VC支撑辊静载凸度特性中的等凸度区。     

VC轧辊的承载特性研究

对控制压力与轧制力共同作用下的VC(variable crown)轧辊的承载特性进行了研究。基于所开发的VC轧辊系统,分析了辊缝形状和辊缝凸度与轧制力及控制压力的关系,提出了临界最大控制轧制力的概念。研究结果表明:当轧制力小于轧辊系统的最大临界控制轧制力时,其板形控制能力优于同规格的实心平辊;当控制压力较大且轧制力较小时,轧辊系统可以实现零凸度或负凸度的负载辊缝。     

四辊轧机板凸度控制能力分析

采用变分法求解金属横向流动,用影响函数法计算辊系弯曲变形,考虑轧辊热凸度,通过耦合迭代的方式,编写热轧钢板凸度计算程序。通过对1450 mm轧机、1780 mm轧机以及2050 mm轧机的板凸度的模拟,分析轧辊挠度、轧辊压扁、弯辊力和热凸度对钢板凸度的影响,为轧机辊系参数的设计提供参考。     

可变凸度轧辊(VC辊)在不同油压下的凸度分布曲线

针对宝钢新近引进的平整机VC轧辊的液压胀形凸度分布曲线的计算问题,提出了一套计算VC辊在不同油压下的胀形曲线的新方法,计算结果与实测值很好吻合,为VC轧机在线设定模型的开发提供了必要的基础。     

热轧铝板带分段冷却闭环控制策略

针对目前热轧铝板带凸度控制存在的问题,建立以轧辊温度在线测量为基础的分段冷却闭环模糊控制系统。以简单的测量设备和控制方法,代替昂贵复杂的板带凸度控制机构。用实际轧制数据训练自适应PSO-BP神经网络,并用训练完成的神经网络依据目标板带凸度得出轧辊温度预设定模型;依据操作人员的经验以及理论分析结果,设计分段冷却模糊控制规则,形成分段冷却闭环控制系统,达到控制板带凸度的目的。经在某厂二辊可逆热轧上的应用,结果表明:轧辊温度偏差量可控制在±4℃内;铝板带纵向各处的凸度95%以上可控制在目标凸度(20~40μm)范围内。该方法充分发挥了分段冷却系统对板带凸度的控制能力。     

轧辊原始凸度对8011铝合金药箔板形质量影响研究

本文结合生产实际,研究轧辊原始凸度对8011铝合金药箔板形质量的影响,结果表明:轧辊原始凸度可对轧制时轧辊的弹性压扁进行补偿,进而影响铝箔板形质量;当轧辊原始凸度为负值或过小,轧制的铝箔会产生边部波浪缺陷,随凸度增大,边部波浪逐渐减轻;当轧辊原始凸度过大,铝箔则产生中间波浪缺陷,并且随着凸度的增大而愈加严重。生产成品规格0.0206×2×1170的8011合金药箔,轧辊原始凸度选择40～60μm有利于控制板形,且轧辊原始凸度为50μm时板形最优,能够满足客户要求。此外,长时间停机或更换工作辊、支撑辊后进行充分的热辊,也有利于板形的控制。     

离散化变凸度辊形的自适应设计方法

变凸度辊形因其优异的凸度控制能力而在板型控制方面应用广泛,但变凸度辊形由于自身的结构特点导致其相对普通辊形而言有着非对称磨损的情况,且大部分的变凸度辊形的设计过程中考虑的主要因素都是辊形的凸度控制能力。针对上述情况,提出了一种离散化变凸度辊形曲线的自适应设计方法,采用遗传算法对辊形数据进行优化。该设计方法以凸度控制能力和轧辊磨损量为辊形评价指标,以该指标建立遗传算法的适应度函数,优化设计辊形曲线。对比CVC(Continuously variable crown)辊形,发现通过遗传算法优化设计后的离散化辊形在保证凸度控制能力的前提下提高了轧辊的抗磨损能力。相较常规设计方法,该设计方法也具有更好的拓展性和灵活度。     

一个轧制单元内实时辊系综合凸度预测及应用

用有限元法在精确计算机械板凸度并在验证其计算结果有效性基础上,通过解析板形刚度理论,解析凸度遗传方程中的遗传系数,建立计算带钢的板凸度方程。利用现场实际生产工艺参数依次计算各架轧机出口带钢凸度并和末机架后凸度仪测量的板凸度值比较,预测热连轧机辊系综合凸度在一个轧制单元内的变化规律。预测结果通过对现场各机架大量的工作辊辊型测量数据经计算后得到验证,在一定工况条件下,预测的辊系综合凸度整体变化趋势和实际辊系凸度变化保持一致。这种预测方法避免了热连轧过程中为精确控制板凸度而计算各单个机架轧辊实时热、磨凸度变化所带来的复杂性,完成了一个轧制单元内实时辊系综合凸度预测值在各单个机架轧机上的凸度分配及应用。应用效果表明,现场带钢板凸度目标值在±10μm内的命中率由91%提高到97%,产品实物质量得到明显改善。所建模型与预测结果对板形理论研究和现场操作实践具有实际参考价值。     

VC轧辊心轴与辊套过盈量的确定

辊套与心轴之间的过盈量δ,是VC(Variable Crown)轧辊系统的关键结构参数之一。从满足其使用性能要求出发,研究了δ的大小对VC轧辊的强度和密封性能的影响,提出了过盈量的选取原则和选取方法。根据该研究结果．心轴与辊套过盈装配后,配合区内端点处的相当应力最大;将在最大控制压力作用下,辊套获得等强度的配合内表面为过盈量的选取准则,可满足VC轧辊的强度、刚度和高压密封要求。     

VC轧机内辊型优化设计技术的开发

针对VC辊轧机在大轧制压力轧制时,套筒塌陷位移抵消VC辊油压凸度、减弱轧机的板形控制效果并引起成品带钢产生双边浪板形缺陷的问题,充分结合VC轧机的设备与工艺特点,提出了一套VC辊内辊型优化设计技术,通过对VC轧辊套筒内凸式辊型的设计,使得轧机在大轧制压力轧制时,套筒内壁与芯轴表面出现局部接触,从而将套筒的塌陷位移控制在允许的范围内,抑制了双边浪等板形缺陷的发生,提高了VC轧机的板形控制范围,进一步拓宽了VC轧机的应用领域。     

ANALYSIS SOLUTION OF BULGING CONVEXITY OF THE HYDRAULIC ELASTIC BULGING ROLL

ＡＮＡＬＹＳＩＳＳＯＬＵＴＩＯＮＯＦＢＵＬＧＩＮＧＣＯＮＶＥＸＩＴＹＯＦＴＨＥＨＹＤＲＡＵＬＩＣＥＬＡＳＴＩＣＢＵＬＧＩＮＧＲＯＬＬＡＮＡＬＹＳＩＳＳＯＬＵＴＩＯＮＯＦＢＵＬＧＩＮＧＣＯＮＶＥＸＩＴＹＯＦＴＨＥＨＹＤＲＡＵＬＩＣＥＬＡＳＴＩＣＢＵＬＧ...     

VC轧机板形控制关键技术的开发与研究

开发出VC辊的空载凸度曲线和负载塌陷位移曲线两项关键技术，在此基础上模拟出VC轧机在不同情况下的板形情况，提出一套工作辊与支承辊优化设计方案，该方案已作为技术规程正式应用于1550CAL VC轧机，使该轧机板形控制在2～4I左右。     

辊间压力分布影响因素的研究

四辊轧机辊间压力的分布将直接影响轧机负载辊缝形状,轧辊磨损情况以及轧辊强度的准确校核。本文采用分割单元法,研究了轧件宽度,轧辊直径,弯辊力,轧辊辊型,轧制压力分布等诸多因素对辊间压力分布的影响,给出了辊间压力分布规律,理论计算值与实测数据吻合较好,研究结果对于板形凸度计算及轧机设计有一定的借鉴作用。     

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 rolling 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 rolls 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-β 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.     

板带轧机工作辊混合变凸度辊形研究

三次连续变凸度(Continuously variable crown, CVC)辊形凸度控制能力与带钢宽度之间的二次函数关系决定其在宽、超宽板带轧机上应用时表现出对窄规格带钢的凸度控制能力不足的缺点。通过对工作辊变凸度辊形及辊缝形成理论的深入研究,提出采用二次多项式曲线来线性化辊缝的方法。采用该方法设计完全线性变凸度辊形曲线与混合变凸度工作辊辊形曲线,使二次辊缝凸度调节能力与带钢宽度在工作辊全长或在设计要求的宽度范围内呈严格线性关系,同时保持与窜辊位置呈线性关系。与CVC辊形相比,混合变凸度辊形的辊径差小、凸度调节能力大,既不削弱对宽带钢的凸度调节能力,又增加对窄带钢的凸度调节能力,从而增强轧机的整体板形控制能力。     

The prediction of roll load in cold roll-forming

Due to the inherent complexity of the cold roll-forming process, machine design procedures have remained highly empirical. There is little information available on the calculation of roll load, though a prior knowledge of this load is essential for the optimum design of the roll stands and the smooth forming of the strip. The present paper describes a semi-empirical method for calculating the roll load. The method is based primarily on equating the external work to the internal dissipation of energy. The estimate has also been modified to take account of the reverse bending of the deformed strip after it reaches the next roll station. The theoretical results have been verified by roll-forming channel sections of mild steel and aluminium and measuring the load with a specially designed quartz dynamometer. The agreement between theory and experiment has been found to be good in spite of the many assumptions which are necessary to simplify the analysis. The results also show how the roll load depends on the material properties, the geometrical parameters of the produced section and the machine dimensions.     

PROFILE AND FLATNESS CONTROL SYSTEM IN 1 700 mm HOT STRIP MILLS OF ANSTEEL

Varying contact-length backup roll and linearly variable crown work roll are provided for improving the mill performance of profile and flatness control. Integrated with theses technologies, relevant profile and flatness control models are developed for hot strip mills on the basis of large amount of finite element calculation. These models include shape setup control model in process control system, bending force feedforward control model, crown feedback control model and flatness feedback control model in basis automation system. Such a profile and flatness control system with full functions is applied in 1 700 mm industrial hot strip mills of Ansteel. Large amount of production data shows that the crown precision with the tolerance of±18 μm is over 90%, the strip percentage which the actual flatness is within ±25 I-unit surpasses 96%, and general roll consume is reduced by 28% by using the profile and fiatness control system. In addition, schedule-free rolling is realized.