中厚板MAS轧制过程的有限元模拟

采用有限元软件ANSYS／LS-DYNA对MAS轧制过程及随后的展宽和精轧过程进行了模拟计算,分析了各变形阶段钢板的形状变化及不同MAS轧制参数对钢板边部形状的影响。结果表明：MAS轧制可以改善轧后钢板边部形状。钢板边部形状的改变不仅与MAS轧制的补偿面积有关,而且与MAS轧制段长度和压下量的比值有关,若MAS轧制参数选取不当,钢板边部会发生“过补偿”现象。根据计算结果选取MAS轧制参数,在中厚板轧机上进行了现场生产试验,效果良好。     

低碳结构钢中厚板MAS轧制过程有限元模拟

根据低碳结构钢Q235(C≤0.20%)4300 mm中厚板现场轧制工艺,采用有限元软件ABAQUS/Explicit建立弹塑性有限元模型对展宽比1.70、精轧伸长率7.87的中厚板普通轧制过程和MAS(水岛平面形状控制轧制法)轧制过程分别进行了模拟计算,对不同变形阶段进行了对比分析。结果表明,MAS轧制法能明显改善中厚板轧后平面形状,其形状的改变量与MAS轧制段设置参数直接相关,对比不同参数下MAS轧制结果得出MAS轧制最优参数△L×△h为300×3。     

立辊轧边的显式动力有限元模拟

应用有限元分析软件ANSYS/LS-DYNA对3种不同形状立辊的轧边过程进行了模拟计算,并对轧边后板坯断面形状和平面形状参数进行了分析比较.模拟计算结果表明:用孔型立辊轧边可增加变形渗透程度,轧后板坯具有较好的断面形状和平面形状,使用孔型立辊和锥形立辊均可提高轧制过程的稳定性.     

基于神经网络的金属应力状态系数模型

 以4200 mm轧机轧制71块钢板的实测数据为基础,利用Matlab神经网络工具箱,分别建立了轧制变形区的应力状态系数与轧前厚度、轧后厚度及轧辊直径对应关系的Elman神经网络预测模型和RBF神经网络预测模型。结果表明,所建立的两种网络模型均建立了金属应力状态系数输入和输出关系,RBF神经网络模型比Elman网络模型数据稳定,性能更优,实现了与实测结果的高度拟合。并得出不同轧辊直径对神经网络模型精度的影响规律,对轧制工艺规程的制定提出了合理建议。     

不同形状立辊轧边变形的有限元分析

基于弹塑性有限元理论 ,利用有限元计算软件ANSYS/LS -DYNA ,对不同形状立辊轧边变形进行了模拟计算 ,并分析了立辊形状对轧后板坯狗骨形状的影响。通过模拟计算发现立轧后板坯头、尾部存在不同程度的失宽 ,狗骨高度最大值出现在板坯中部 ,采用孔型立辊或锥形立辊可提高轧制过程的稳定性     

“哑铃状”平面形状轧制法在中厚板生产中的应用

中厚板轧制过程中,由于板坯在长度和宽度方向的端部会产生不均匀变形,使轧后的钢板平面形状一般非矩形,从而造成钢板的切头、切尾和切边量增加,严重影响中厚板成材率。根据不同坯料规格和展宽比条件下的塑性变形特点,在轧机负荷和液压系统硬件配置不变的前提下,采用轧件的“哑铃状”轧制法进行平面形状控制,通过长度精准计算模型及打滑因子修正方法,实现轧件长度的精准跟踪;通过多点设定方法,得到更加精细化的平面形状控制曲线,使最终产品达到切头、切尾量最优化要求。“哑铃状”轧制法投入实际应用后,与传统轧制法相比综合成材率平均提高了0.59%。     

MAS轧制法在中厚板3500mm轧机的应用

MAS轧制法是一种中厚板平面形状控制方法,在成形及展宽末道次进行可变压缩,旋转90°后再轧制得到矩形化程度较高的钢板。唐钢中厚板公司对轧机液压及自动化系统改造后,满足了MAS轧制法应用的设备条件。根据现有平面形状控制模型,研究了模型参数的含义,结合现场不同产品规格进行工业试验,优化模型参数,有效地减少了钢板头尾及边部的不规整变形,提高了钢板的矩形化程度,成材率提高0.8%。     

唐钢3500mm轧机平面形状控制的研究与应用

唐钢3 500 mm中厚板生产线产品的钢种和规格较多,展宽比不合适时,钢板的矩形度难以保证,造成切损量多,成材率低。平面形状控制技术就是根据坯料在不同展宽比和延伸比条件下头、尾、边部的不均匀变形程度,在成形、展宽过程中进行变厚轧制,以改善钢板矩形化程度,减少头尾和边部剪切损失,提高成材率。唐钢中厚板材有限公司通过轧机设备改造,实现了轧机的平面形状控制功能。该功能投用后四切成材率提高了0.8%。     

3300mm铝板热轧机角轧的有限元模拟

根据角轧的轧制特点,利用小型重启动技术,借助有限元模拟计算软件ANSYS/LS-DYNA,建立角轧两个道次的显式动力学可逆轧制模型,分析了不同投入角度、压下量和轧件宽度等工艺条件下2024铝合金角轧时展宽量的变化规律。结果表明,展宽量随着投入角、压下量和轧件宽度的增大而增大。可以此计算结果为基础,综合分析如何制定轧制规程以获得不同宽厚比的轧件。     

中厚板边部折叠模拟实验及机理研究

通过对中厚板边部折叠试样的检测分析,对其产生机理和影响因素进行研究.结果显示,中厚板边部折叠现象是板材横轧宽展过程中侧面材料在轧制中受轧辊作用而翻转到板材表面的结果.折叠缺陷处所观察到的微观组织结构,是轧制前板材表面在高温下形成的氧化铁及脱碳层形成的.建立了轧制有限元数值模型,证实折叠缺陷是在轧制过程中由侧面的折叠翻转所造成的.通过实验室实验,得到铸坯边部质量、轧制制度、宽展道次及轧制压下量对中厚板折叠缺陷的影响.实验结果表明横轧宽展导致折叠缺陷的出现,铸坯边部质量对其没有影响,轧制过程中铸坯侧边的折叠经翻平形成表面折叠缺陷,随着横轧展宽的道次及压下量增加,折叠缺陷距边部距离变大.      

Regression models for predicting plate plan view pattern during wide and heavy plate rolling

Abstract

On the basis of Shagang Group’s 5000 mm heavy plate mills, conventional rolling processes with different broadside rolling ratios were simulated by the three-dimensional rigid plastic thermomechanical finite element (FE) model developed in the author’s previous work. By analysing the simulation results, it was found that the final plate plan view patterns after hot rolling processes were bound closely to the broadside rolling ratio and the finishing rolling ratio. Then, predictive models for plate end edge shapes and side edge shapes were formulated by nonlinear regressive analysis of the simulation results and modified by the lengths of the uneven shapes for higher accuracy. The validity of the prediction models was confirmed by comparing the predicted concavity and convexity lengths with those measured from industrial tests. The predicted plate edge shapes were in good agreement with those of the FE simulation. On the basis of the plate plan view pattern prediction models, methods to improve the plate plan view pattern are discussed.     

Broadside Compensation Rolling Model for Plan View Pattern Control in Wide and Heavy Plate Rolling Process

On the basis of a 5 m plate mill, a 3D rigid-plastic finite element （FE） model was developed to investigate changes of plate plan view patterns during hot rolling process. By analyzing the simulation results of conventional rolling processes, it was found that the plate plan view pattern was closely related to broadside rolling ratio. Then, the prediction models for plate plan view patterns were formulated by nonlinear regressive analysis of the simulation results and modified for high accuracy. Based on these models, the broadside compensation rolling method perform- ing at the last pass of broadside rolling phase was designed to decrease plate end crops. Comparing the plate plan view patterns with and without broadside compensation roiling, reduced plate end crops indicate that the broadside compensation roiling model is effective for plate plan view pattern control.     

Optimisation of edging amount for high accuracy plan view control in plate mill

Algorithm to optimise the edging amount for high accuracy plan view control has been developed to improve plate yield. To produce rectangular shape of rolled plate, the edging amount that can minimise the crop length and width deviation must be determined from the operational analysis of plate mill. For the plan view control, new mathematical models to predict crop length at the top and bottom ends and width deviation at side ends are developed on the basis of statistics and back propagation learning algorithm of neural network. Using new mathematical models, under given rolling conditions of broadside and finishing pass and the permissible tolerance in width deviation, optimised algorithm which can achieve high accuracy plan view pattern is proposed. The application of newly developed algorithm in actual plate mill for plan view pattern control reduced width deviation by 20%, and crop length by 30% on average with a suitable fishtail crop shape.     

Precision Plate Plan View Pattern Predictive Model

 According to the rolling features of plate mill, a 3D elastic-plastic FEM(finite element model) based on full restart method of ANSYS/LS-DYNA was established to study the inhomogeneous plastic deformation of multi-pass plate rolling. By analyzing the simulation results, the difference of head and tail ends predictive models was found and modified. According to the numerical simulation results of 120 different kinds of conditions, precision plate plan view pattern predictive model was established. Based on these models, the sizing MAS (mizushima automatic plan view pattern control system) method was designed and used on a 2800 mm plate mill. Comparing the rolled plates with and without PVPP (plan view pattern predictive) model, the reduced width deviation indicates that the plate plan view pattern predictive model is precise.     

板材轧制头部翘曲的非线性有限元研究

根据宝山钢铁集团公司2050 板材热轧生产工艺,采用弹塑性有限元法建立了热力耦合非对称轧制仿真模型.利用该模型分析了非对称轧制过程的非对称机理,研究了不同轧制工艺下的辊速比、上下表面温差对板材头部翘曲的影响规律,同时实现了通过调整辊速比控制厚向非对称温度分布造成的板材头部翘曲.根据不同工艺参数下控制部翘曲的计算结果,利用Matlab程序回归建立了控制上下表面温差引起板材头部翘曲的辊速比设定数学模型.     

轧机机架辊损坏原因分析及改造

针对邯钢中板轧机机架辊存在的辊径断裂、辊面粘钢等问题,通过辊子载荷计算及辊面粘钢机理的研究,确定了机架辊损坏的原因。提出机架辊改造方案,辊径由~190mm增加到p220mm,提高了承载能力;改用滚动轴承;改进辊面材料提高辊面的耐磨性和强度。经过多次运行证明,改造后其使用寿命及其它综合性能得到大幅度提升,满足中板线生产的需要。     

热塑有限元的理论分析及应用

利用热塑有限元对板材轧制过程进行模拟计算,能够计算轧制力、轧制力矩、辊形、板形等参数,对板材轧制起到定量计算的作用。热塑有限元在板材生产中能计算最佳辊型、板形、弯辊力、串辊位置以及压下制度,达到提高成材率、提高板材质量的目的。热塑有限元是一种三维的弹塑性有限元,它应用的本构方程是由试验数据回归得来的,使用了加工硬化、拉拔效应等计算方法,计算结果精确。     

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。