冷轧带钢卷取过程中受力与变形研究

带钢卷取和卸卷两道工序由于卷筒约束的变化,两种状态下钢卷的内部应力场存在变化,尤其是在卷芯部位应力场的变化较为显著,这也是带钢头部存在多种质量缺陷的区域.基于现场实测和紧密系数的实验研究,通过卷取过程应力场的差分求解以及卷取结束后卸卷过程中机械应力和热应力耦合应力场的差分法求解,获得了钢卷内部应力场的分布规律,为生产现场预防及控制卷取和卸卷过程中产生的各类缺陷提供了有效的技术对策和理论依据,使机组的产品板形质量和成材率明显提高.     

考虑附加接触变形的冷轧板带卷取过程模拟

在卷取过程中，由于卷取张力的作用与板带的弯曲变形会使带卷内部产生压应力，随着卷取层数的增多，压应力会增大。在实际生产中，由于板带存在表面粗糙轮廓，在压应力的作用下，除了板带本身会发生弹性变形外，各层表面粗糙轮廓相互接触时，在径向方向上也会产生附加接触变形，这在很大程度上影响了带卷内部的应力分布。在传统的解析方法中，卷取过程被视为薄壁筒逐层嵌套的轴对称模型。该模型往往通过改变径向弹性模量来体现层间接触带来的附加变形，然而当板带的材料、厚度以及表面粗糙度不同时，采用该方法计算径向弹性模量可能会出现偏差，且逐层嵌套模型与实际的缠绕型卷取存在差异。对于该差异，采用有限元方法对卷取过程的模拟更符合实际情况，但是针对具有附加接触变形的有限元研究未见报道。因此，为了克服上述方法中存在的不足，利用有限元软件MSC. Marc通过垫片单元建立了考虑接触附加变形的板带卷取模型，通过叠片压缩试验得到了板带附加变形量与压力的变化规律曲线，并将该曲线引入垫片单元来考虑接触附加变形，进而研究附加接触变形对带卷内部应力与卷筒所受压力的影响。     

带钢卷取过程起筋控制的建模与仿真

 为了研究带钢局部高点卷取过程起筋的控制方法,基于应力函数假设和S Timoshenko最小功原理获得了起筋带钢的应力场分布,并采用伽辽金虚位移原理建立了可用于在线计算的起筋临界卷取张力设定模型和起筋弹性极限模型。并对应力场分布和临界卷取张力各影响因素进行仿真研究,仿真结果表明：局部高点在径向累积叠加所引起的带钢张力不均匀分布和轴向压应力是导致带钢起筋的主要原因;临界卷取张力随带钢厚度、局部高点高度和卷取半径增大而减小,带钢宽度对钢卷的起筋临界卷取张力影响非常小。通过与实际生产控制方法和ANSYS有限元分析结果对比,验证了本模型的计算精度和可行性。     

冷轧钢卷卷取过程内部应力三维分布的研究

冷轧钢卷卷取过程中,带材的板形与板凸度以及卷取张力的横向分布决定钢卷内部的应力分布。同时,带材与卷筒之间、带材与带材之间的摩 擦力对应力分布的影响不可忽略。此外,由于层间接触表面缝隙的存在,钢卷必须按各向性体处理。基于上述因素,提出了一套新的三维数学模型,以计算钢卷内部应力分布,并根据降低钢卷在罩式退火粘经率的要求,研究了钢卷的卷取张力制度。     

热轧带钢卷取张力对钢卷品质的影响分析

从热轧带钢卷取的钢卷品质缺陷及其影响因素分析人手,指出卷取张力是热轧带钢卷取生产控制中的关键工艺参数,其取值的大小是否合理直接决定了带钢在卷取、卸卷、冷却过程中的钢卷品质和下游工序开卷质量。随后主要就卷取张力与卷取钢卷品质关系模型的建立,钢卷在卷取过程中的内部应力场求解,卷取张力的优化,所开发分析软件的工程验证等方面进行阐述。本文介绍的分析模型既可用于卷取张力预报和在线设定,指导现场生产,又可用模型计算数据来指导卷取设备的设计。     

冷轧带钢局部高点卷取过程起筋控制的建模与仿真

为了研究带钢局部高点卷取起筋的控制方法,利用三维弹塑性变形基本理论,并引入带钢塑性流动因子,建立了弹塑性卷取应力和起筋量模型.基于应力函数假设、S.Timoshenko最小功原理和伽辽金虚位移法建立了起筋带钢的应力场分布和可用于在线计算的起筋临界卷取张力设定模型.仿真结果表明:局部高点在径向累积叠加所引起的带钢张力不均匀分布和轴向压应力是导致带钢起筋的主要原因;起筋量随局部高点高度、卷径和卷取张力增加而增大,薄带钢比厚带钢起筋量增幅明显;临界卷取张力随卷径、带钢厚度和局部高点高度增大而减小.      

热轧带钢卷取温度对卷后应力影响研究

基于闭口圆筒的平衡方程、协调条件和本构关系,建立了热轧带钢卷后自然冷却过程的热致变形场理论模型,系统研究了典型温度波动形式和发生区域,对比不同厚度规格带钢的卷后应力演化的影响规律。将带钢卷取温度波动归纳为3类型式:L型、V型和反Z型,考虑其发生在带钢的带头段、中间段和带尾段。模拟结果表明,热轧带钢卷后应力的变化主要受卷取温度波动的影响,温度波动的位置越靠前、产生温降的层数越少和温差幅值越大,钢卷层内应力降低幅值越显著;相同厚度规格的带钢,发生L型温降波动时,其卷后层内应力降低幅值最显著,V型和反Z型依次次之;不同规格的带钢,发生L型温降波动时,其厚度越厚产生层内应力的降低幅值越大,而对于V型和反Z型温降波动,带钢厚度对其层内应力变化几乎无影响。本文研究结果对于优化热轧带钢的卷取温度策略从而提升钢卷下机后质量具有参考价值。     

极薄镀锌基板的塌芯缺陷及对策

针对极薄镀锌基板开发中出现的塌芯缺陷,通过分析下线钢卷层间的受力和形变,得出带钢层间环向均匀分布的径向压力大于局部薄弱部位的屈服强度是此缺陷产生的根本原因。通过降低设定卷取张力、增加带钢层间摩擦系数、降低轧制温度、精心操作、优化启车张力制度等综合措施,减小了层间径向压力,增大了钢卷失稳临界压力,使塌芯缺陷得到有效控制。     

卷取张力锥形控制的研究与应用

针对单机架平整机的带钢头部滑伤问题,分析了钢卷径向压力、卷筒的工作原理、及带钢头部滑伤形成原因,提出了卷取张力采用锥形控制的新方法。     

改善带钢卷取质量的措施

从卷取机卷筒涨缩液压系统和张力控制液压系统对带钢卷取质量的影响入手,通过对涨缩液压系统和张力控制液压系统进行改进,解决了冷轧处理线卷取机在带钢卷取时频繁发生的带头在卷筒上打滑、张力无法建立、钢卷内圈溢出、褶皱及梗印等问题。     

Modeling of Stress Distribution During Strip Coiling Process

 Many strip materials are coiled after rolling process. The stresses are imposed on the material wound on the automatically controlled collapse mandrel under the coiling tension. The coiling process can be described by three typical cases: winding without automatic adjustment, winding with automatic adjustment and after mandrel removal. A new model of equations for predicting the stresses during the strip coiling process is built by consideration of the three cases respectively. By solving the equations of different typical cases, the radial stresses and tangential stress of the layers of coil can be calculated. Also, the coiling parameters, such as strip thickness, coiling tension and necking critical pressure, affecting the coil performance are investigated. It is believed that the present model can be used for design and control of the automatically controlled collapse mandrel.     

热镀锌卷尾部塔形缺陷的分析和预防措施

通过对热镀锌板卷取过程中产生卷尾塔形的分析,得出卷取张力不匹配和套筒与芯轴打滑是造成卷尾塔形缺陷的主要原因。通过改造张力卷取机的芯轴,采用恒张力控制和恒扭距控制相结合的卷取模式,优化卷取张力,有效地避免镀锌板卷尾塔形的产生。     

Stress–Strain State of Coiled Steel

In a new mathematical model of the stress–strain state of steel strip in the course of cooling, the nonplanarity, surface roughness, and transverse thickness variation (convexity of the cross section) are taken into account. The stress–strain state of a coil of thin steel sheet has a significant influence on factors such as the temperature distribution in the coil; the scale formation on cooling in the course of hot rolling; the adhesion of adjacent turns in the annealing of cold-rolled strip; and the shape of the coil itself. The mathematical model is based on representation of the coil as individual nested hollow cylinders of finite length. The cylinders are divided into sections over the width. The sum of solutions of the Lame equation for individual sections is shown to converge to the solution for the cylinder as a whole. The model permits calculation of the coil’s stress–strain state, taking account of gap formation between adjacent turns as a result of the transverse variation in strip thickness. The modeling results show how the radial and tangential stress formed in strip winding is distributed within the coil. The model permits calculation of the stress–strain state of the coil in the winding of even strip; in the winding of convex even strip with no tension; in the loose winding of convex even strip with tension less than that in tight winding; in tight winding of even convex strip with the correct tension; and in the winding of convex uneven strip without tension. The decrease in distance between contacting rough surfaces is calculated on the basis of a probabilistic approach. An algorithm is presented for calculation of the coil’s stress–strain state. The result obtained for the stress distribution in the coil is typical for the winding of steel strip. The model is verified for the winding of hot-rolled strip, in terms of the size of the region with tight contact of adjacent turns. The tightness of contact is assessed on the basis of the temper color on the edges of the hot-rolled strip. The discrepancy between the calculated and measured size of the region with tight contact is 3%.     

川威950热轧带钢的卷取控制

结合川威950热轧工程卷取区的控制,介绍卷取设备、工艺、自动控制系统组成,详细阐述卷取逻辑控制和张力控制、APC、卷径计算、尾部定位等控制算法及思想。     

A Model Coupling Method for Shape Prediction

 The shape of strip is calculated by iterative method which combines strip plastic deformation model with rolls elastic deformation model through their calculation results, which can be called results coupling method. Because the shape and rolling force distribution are very sensitive to strip thickness transverse distribution′s variation, the iterative course is rather unstable and sometimes convergence cannot be achieved. In addition, the calculating speed of results coupling method is low, which restricts its usable range. To solve the problem, a new model coupling method is developed, which takes the force distribution between rolls, rolling force distribution and strip′s exit transverse displacement distribution as basic unknowns, and integrates strip plastic deformation model and rolls elastic deformation model as a unified linear equations through their internal relation, so the iterative calculation between the strip plastic deformation model and rolls elastic deformation model can be avoided. To prove the effectiveness of the model coupling method, two examples are calculated by results coupling method and model coupling method respectively. The results of front tension stress, back tension stress, strip′s exit gauge, the force between rolls and rolling force distribution calculated by model coupling method coincide very well with results coupling method. However the calculation course of model coupling method is more steady than results coupling method, and its calculating speed is about ten times as much as the maximal speed of results coupling method, which validates its practicability and reliability.     

冷轧卷取机胀缩机构的故障分析

冷轧卷取机胀缩机构在使用过程中轴向斜楔头部的断裂问题是影响板带材连续生产的一个主要技术难题,通过卷取过程钢卷箍紧力计算、胀缩机构的受力及其自锁条件分析及胀缩过程的有限元仿真,合理解释了轴向斜楔头部断裂的原因,同时也为胀缩结构的设计及其润滑条件提供了重要的参考依据。     

热风炉设计不应片面追求蓄热面积

热风炉蓄热室是热交换的主要场所。要想提高热风炉的效率,需按照蓄热交换的基本特性综合考虑,而不应片面追求蓄热面积的增加。