Improving the quality of rolled pipe steel products by minimizing the bending of the ends of plates

The causes of the vertical bending of the front ends of plates during hot rolling are revealed. A finite-element mathematical model is developed to describe the state of stress of the metal in an asymmetric deformation zone with allowance for solving a temperature problem, and the model is adapted to the conditions of the 5000 rolling mill in OAO MMK. It is found that, in rolling with mismatched work roll speeds, the direction of bending of the front strip end is determined by the strip thickness and the deformation zone shape. The main cause of the bending of the front plate end at the stage of finishing stage of rolling is shown to be the difference between the roller bed level and the rolling line. New asymmetric deformation regimes are developed with allowance for the effect of the deformation zone shape on the direction of bending of the front strip end. The developed technological regimes of asymmetric rolling make it possible to decrease the mill downtime because of the bending of the breakdown bar ends and to reduce the metal volume rejected because of violated temperature regimes of the thermomechanical treatment of plates.     

板带轧制过程多参数耦合模拟系统的开发

考虑轧件和辊系间的接触力与变形协调关系，采用一种选代的方案，开发了一个分析三维板带轧制过程的计算机模型。它耦合了计算轧件变形的三维刚塑性有限元法，计算辊系变形的影响函数法和弹性有限元法。该系统可用来精确预报轧制压力横向分布，前后张力横向分布，金属横向流动，以及轧后板带的横向板厚分布，包括板凸度和边部减薄等，并且具有较高的计算效率。     

2250 mm CVC四辊热轧机轧制带钢金属的横向流动

 为了提高2 250 mm CVC四辊热轧机板形控制精度，使用非线性有限元软件MSC Marc建立了动态刚性轧辊-弹塑性轧件耦合模型，分析了带钢金属的横向流动规律。为提高精度，采用静态弹性辊系-弹塑性轧件耦合模型得到有载辊缝形状作为动态仿真的初始辊形。分析发现，金属横向流动值随着距轧件中心距离的增大逐渐增大；摩擦力是影响不同厚度间金属横向流动差别的重要因素；金属的横向流动量与压下率、弯辊力、来料凸度以及窜辊量呈线性关系。为了定量分析各因素与横向流动的关系，建立了各因素的影响系数函数，并进行正交试验及方差分析判断交互关系，最后建立插值计算模型，并通过仿真结果验证了其正确性，为相应轧机的在线板形控制提供参考。     

新型电磁调控轧机弯辊辊型电磁补偿及初始辊缝

 为解决薄带轧制过程中的各类板形问题,以新型电磁调控轧机为研究对象,利用Marc建立三维热-力耦合有限元模型,分析了弯辊和电磁调控轧辊综合作用下弯辊力和轧制力对轧辊辊型状态、板形分布、板坯边部应力、辊间接触应力、承载辊缝形状的影响规律。结果表明,弯辊机制的施加将直接促进电磁调控轧辊的稳定胀形,使电磁调控轧辊胀形凸度得到整体性补偿,并以板形良好为依据,给出新型调控轧机合理的弯辊力施加范围。对比分析了不同弯辊力和轧制力下辊缝函数的变化情况,形成不同的二次、四次凸度,为板形控制及初始辊缝设定提供依据。     

板形理论的进步与应用

金属塑性加工中板形理论的进步分三个阶段轧辊变形理论;轧件变形理论;轧件轧辊统一变形理论.本文推导出了四维轧制差分方程,以厚度为控制量的二维板形差分方程,以轧辊实时凸度和弯辊力为控制量的二维板形差分方程.构造了二次型目标函数,可用贝尔曼动态规划方法求出板形板厚最优控制综合,轧辊实时凸度估计和最佳弯辊力设定.     

热轧带钢金属横向流动及影响因素

提出了一种分析热轧带钢金属横向流动问题的新方法.首先使用ANSYS软件建立辊系-轧件静力学耦合模型,计算并提取变形后工作辊有载辊形曲线;然后使用ANSYS/LS-DYNA建立动力学分析模型,采用己得到的有载辊形曲线,模拟带钢轧制过程,求解得到沿带钢全宽的横向流动状态;并进一步分析了弯辊力、工作辊辊形以及来料凸度变化等因素对带钢金属横向流动的影响,得到基于插值计算的带钢横向流动计算模型.有限元方法验证了计算模型的可靠性.      

宽带钢冷轧机辊系纵向刚度特性对比

针对目前广泛使用的CVC和HC两种主要轧机机型,利用大型有限元软件ANSYS 9.0建立了三维辊系有限元模型,分析了不同机型的四辊和六辊轧机在不同窜辊、弯辊工况下的轧制力纵向刚度和弯辊力纵向刚度的变化情况.在相同工况下的四辊轧机的轧制力纵向刚度要大于六辊轧机.中间辊窜辊或工作辊窜辊对HC轧机的轧制力纵向刚度和弯辊力纵向刚度的影响要大于CVC轧机.      

弯辊力对带材板形影响的有限元分析

应用有限元ANSYS/LS-DYNA软件,建立了300mm可逆式冷轧机弯辊模型,模拟了在同一轧制条件下不同弯辊力对板形和工作辊弯曲变形的影响.通过对模拟结果的分析,给出了比较理想的弯辊力值,对以后的生产实践具有一定的指导意义.     

三辊定减径机轧后钢管弯曲的原因分析

无缝钢管经过三辊定减径机轧制生产工序后,有时会产生弯曲,影响产品质量和深加工.通过研究管材纵轧变形机理,从摩擦系数、变形抗力和前滑等几个方面分析了轧辊辊径、轧辊硬度、轧件温度的变化对三辊定减径机轧后钢管弯曲产生的影响.     

层状金属复合材料的发展历程及现状

三十多年来,多种层状金属复合材料的制备方法应运而生,蓬勃发展,包括爆炸复合法、轧制复合法、热压扩散法和沉积复合法等。爆炸复合法在中厚板的制备上具有不可替代的优势,其产品广泛应用于军工、船舶、电力和化工等领域。轧制法可以批量生产大尺寸层压板,应用最为广泛,目前层压板已经广泛用于汽车、船舶和航空航天等领域。真空热压扩散法由于可以避免氧气等气体的污染,几年来在Ti/Al、Ti/TiAl和Ti6Al4V/TiAl层状复合材料的制备上备受关注。沉积复合法制备的层状金属复合材料在作为耐蚀、耐磨涂层,高强导线,人体植入材料方面表现出巨大的潜力。在综述层状金属复合材料发展历程的基础上,介绍了层状金属复合材料的制备方法及各自的优缺点,并对层状金属复合材料目前在国内外的研究现状进行了分析和介绍。      

不锈钢/碳钢复合板平整轧制过程板形翘曲行为

 针对不锈钢/碳钢复合板在平整轧制过程中极易出现不均匀延伸并导致板形翘曲的行为,建立了不锈钢/碳钢复合板平整轧制过程的有限元数值模拟模型,对已实现工业化批量生产的不锈钢/碳钢复合板平整轧制过程的不均匀变形行为及其可能导致的板形翘曲缺陷进行数值模拟研究。在此基础上,对比分析了均质板、非对称不锈钢/碳钢复合板以及对称不锈钢/碳钢/不锈钢复合板平整轧制过程板形的遗传与演变规律,发现仅非对称不锈钢/碳钢复合板在平整轧制过程中极易产生板形翘曲缺陷,同时对比分析了平整和常规轧制对非对称不锈钢/碳钢复合板轧后翘曲缺陷的影响。揭示了不锈钢/碳钢复合板厚向分层特征以及复合板尺寸参数、平整工艺和平整机设备参数等对其板形翘曲缺陷的影响规律,研究表明,对复合板尺寸参数而言,平整过后翘曲高度与厚度比呈正比。对于平整工艺而言,当等张力平整轧制时,平整过后翘曲高度与张力呈正比;当不等张力平整轧制时,前张力的变化对平整过后翘曲缺陷的影响较大;同时平整过后翘曲高度与轧辊和碳钢层表面摩擦因数呈反比。对平整设备参数而言,平整过后翘曲高度与碳钢层表面接触的轧辊辊径、入口侧防皱辊抬起高度以及不锈钢层表面接触轧辊偏向入口侧的距离均呈正比关系。最后,采用轧制试验对数值模拟结果进行了验证,证明了复合板平整轧制模型的准确性。基于上述研究结果,提出了相应的工艺对策,为金属复合板平整轧制过程的板形翘曲控制提供了理论依据。     

Research and Application of Dynamic Substitution Control of Actuators in Flatness Control of Cold Rolling Mill

The work roll bending control has a strong ability to eliminate the symmetrical flatness defects of strip. However, if the incoming strip is coming with severe symmetrical flatness defects, it happens that the position limit of work roll bending is prone to be reached or exceeded during the execution of the displacement, resulting in the residual symmetrical flatness defects without further elimination, as well as a limited flatness control process. Abilities of work roll bending and intermediate roll bending / shifting for flatness control have been analyzed based on the actuator efficiencies for the purpose of solving the problem of work roll bending control reaching threshold. Meanwhile, a self‐learning determination model of actuator efficiency factors, which can be utilized to determine the actuator efficiency factors online accurately, was developed from the measurement data extracted from the rolling mill. Models of intermediate roll bending and intermediate roll shifting substitution control in case of work roll bending control over‐limitation have been developed, in accordance with the practical conditions and the degree of work roll bending over‐limitation. Applications show that the substitution control can play an important role in the residual symmetrical flatness deviation control, which should have been removed completely by the work roll bending control.     

芯辊直径对异形环件热轧变形影响的有限元研究

采用Simufact软件建立了大型异形截面环件辗扩过程的三维有限元模型,模拟计算并揭示了芯辊直径对环件热辗扩过程中的等效应变、轧制力、环件尺寸的影响规律。结果表明:随着芯辊直径的增大,在径向孔型中,会导致金属在环件内表面流动阻力增大,从而使环件内表面等效应变减小,而在轴向方向,上下表面等效应变并没有明显变化;芯辊与环件内表面接触面积变大,使更多金属发生塑性变形,使径向轧制力逐渐增大,而轴向轧制力的变化趋势并无明显变化;在环件尺寸方面,芯辊直径的变化对环件尺寸的影响并不明显。     

A kinematic analytical approach to predict roll force,rolling torque and forward slip in thin hot strip continuous rolling

Abstract

A kinematic analytical approach has been developed to predict the roll force, rolling torque and forward slip in thin hot strip continuous rolling under various rolling conditions. The approach is based on formulating a velocity field in the roll bite zone that expresses the effect of interfacial friction on the distribution of axial velocity and longitudinal stresses across the strip thickness. The results obtained from the proposed approach are in fair agreement with finite element simulation results, whereas available analytical methods, which are usually valid for billets and thick plates, have given considerable error in the results. The proposed approach is applied to study the effect of thickness reduction ratio, coefficient of friction, work roll diameter and front and back tensions on the roll force, rolling torque and forward slip in thin hot strip rolling. The main merit of the proposed analytical approach, as compared to finite element simulation, lies in the drastic reduction in the computational time required in finite element simulation, which favours its use in online control of rolling thin strips.     

六辊冷连轧机板形前馈控制模型的研究

冷连轧过程中,轧制力波动对板形的影响很大,需要采用弯辊力进行实时的补偿。针对六辊冷连轧机,分别研究了仅用工作辊弯辊和采用工作辊与中间辊弯辊相结合的板形前馈控制模型。实际控制效果表明,这两种板形前馈控制模型都能有效消除轧制力波动对板形产生的不利影响;采用工作辊弯辊的板形前馈控制模型只能控制由于轧制力波动产生的二次板形,而对四次板形几乎不产生影响;而采用工作辊与中间辊弯辊相结合的板形前馈控制模型则对二次和四次板形均具有很强的控制能力。     

平整机辊系变形的有限元分析

通过对辊系变形的模拟,分析了轧制条件下对工作辊弯曲变形、支撑辊弯曲变形及接触应力的影响,借助大型有限元分析软件ANSYS的手段,对辊系进行了弹性力学结构分析,得出了在轧制过程中辊系的变形情况及载荷分布等详细直观的分析结果。     

方矩形管端部成型机制

 利用非线性有限元方法,结合实际生产中方矩形管辊压成形过程,建立了有限元仿真模型。基于该模型对7机架实际辊压成型过程进行了模拟运算,得到了成形过程中稳定段处节点位移矢量、应力和应变的分布情况。通过对仿真计算结果的分析,得到管头端面上在角部和边部的过渡区存在着“位移中性面”,在端面上角部和边部的中心处伴有明显的金属“外翻”和“内翻”的情况,仿真结果与现场轧制结果相符。     

FEM Analysis of Rolling Pressure Along Strip Width in Cold Rolling Process

 Using 3 D elastic plastic FEM, the cold strip rolling process in a 4 high mill was simulated. The elastic deformation of rolls, the plastic deformation of the strip, and the pressure between the work roll and the backup roll were taken into account. The distribution of rolling pressure along the strip width was obtained. Based on the simulation results, the peak value of rolling pressure and the location of the peak were analyzed under different rolling conditions. The effects of the roll bending force and the strip width on the distribution of rolling pressure along the width direction were determined.     

四辊平整机辊系与带材耦合变形有限元分析

 采用大变形弹塑性有限元法将辊系弹性变形与带材弹塑性变形耦合在一起建立四辊平整机三维模型。研究了不同宽度和厚度下工作辊弯辊力对辊系变形、辊缝形状及轧件出口厚度的影响规律。计算结果对平整机设备设计和生产工艺制定具有实际参考价值。所建模型也为轧制过程离线分析提供了一种有力的手段。     

Electrical rolling of a metal powder in roll electrodes with a high-density current

The effect of roll electrode voltage on the electrical rolling of metal powders is considered. Formulas for voltage computation during electrical rolling are derived. The breakdown voltages of powder materials are determined experimentally. The optimum values of voltage during the electrical rolling of widespread metal powders are established.