轧制60 kg/m高精度重轨半万能和全万能成品孔的研究

 对重轨万能轧制法中，使用半万能成品孔和全万能成品孔轧制高精度重轨产品尺寸和形状精度进行了分析研究，对两者轧制高精度重轨进行了实验对比。并借助有限元分析软件ANSYS/LS DYNA，对采用全万能成品孔轧制60 kg/m高精度重轨的变形情况进行了模拟，验证了全万能成品孔型的可行性。结果表明，轧制高精度重轨的最好方法是使用全万能成品孔。     

60 kg/m高精度重轨的万能轧制及有限元模拟

我国高速铁路的发展要求重轨生产必须实现高精度轧制.对使用半万能成品孔和全万能成品孔轧制高精度重轨产品的尺寸和形状精度进行了分析研究,提出轧制高精度重轨应采用全万能成品孔型.借助有限元分析软件ANSYS/LS-DYNA,对采用全万能成品孔来轧制高精度重轨的变形情况进行了模拟,模拟结果也证实了采用全万能成品孔的可行性.     

三种成品孔轧制高精度重轨尺寸和形状精度的研究

对使用两辊成品孔型、半万能成品孔型和万能成品孔型轧制高精度重轨的产品尺寸精度和形状精度进行了研究,在生产条件下进行两辊成品孔型的轧制实验,在实验室进行半万能成品孔型和万能成品孔型轧制高度重轨的实验,三种孔型均可以轧制出满足200km/h2和300km/h标准要求的高精度重轨,成材率和尺寸精度依次为万能孔型和两辊孔型。     

重轨万能连轧变形计算的数学模型及其应用

分析了重轨万能轧制精轧机组UR、ER/EF和UF三机架的变形特点,并建立了相应的数学模型。对U71Mn钢(%:0.7C、1.0Mn、0.1Cr)60 kg/m重轨的连轧计算结果表明,模拟值接近设计值,轨头和轨底宽度中间道次误差分别为0.13%～0.66%和0.45%～1.3%,较好地反映了轧件轨头和轨底宽度的变化趋势。     

用连铸坯轧制重轨的变形模拟实验

以铅为实验材料，在实验室二辊φ100mm开坯机上采用网格法模拟了以连铸方坯为坯料轧制重轨时轧件的变形规律，研究了压下规程及轧制速度对轧件在不同孔型轧制时变形等效应变分布的影响，发现等效应变分布的基本规律性，为制定合理的重轨压下规程及采用连铸坯轧制重轨提供了实验依据。     

重轨万能连续轧制过程温度预报的数学模型

针对万能可逆连轧重轨轧制过程,选取了适用于轨形孔型、万能孔型轧制阶段合理的温度变化数学模型,编制了预报不同时刻重轨轨头、轨腰、轨底半均温度的计算程序.结果表明,轧制过程轨腰温度最高,轨头其次,轨底最低,轨头、轨腰、轨底温度的预报值与实测值的相比,误差分别为≤11.4℃、≤14.5℃和≤9.8 ℃.     

重轨的高精度轧制技术现状

介绍了国外万能轧制技术的原理，设备配置，孔型设计及对重轨断面尺寸精度的影响；分析了传统轨梁轧机的因有问题及造成重轨几何尺寸超差的根本原因，提出了万能轧机轧制重轨是当代提高重轨轧制精度的有效方法。针对攀钢的实际情况提出了建议。     

BD2四孔打卫板的原因及解决措施

轧制重轨时,由于BD2第四孔特殊的孔型结构,轧件不容易脱槽,这就需要借助卫板将轧件引导出孔型,以免发生缠辊断辊等生产事故。但是由于多种原因,卫板很容易被轧件打断。卫板断后不得不停机处理,处理起来不方便且耗时较长,影响整个生产计划。以50kg/m重轨的轧制为例,从孔型结构、卫板特点、四孔开轧温度等方面介绍了BD2四孔打卫板产生的原因及解决办法。并对其他型号重轨的轧制起到指导作用。希望能大幅减少卫板被打事故的发生机率。     

采用6个轨形孔系统轧制60kg/m重轨

本文在介绍苏联重轨的孔型系统的基础上,着重论述了采用六个轨形孔轧制60kg/m重轨的孔型系统选择、孔型设计特点及轧辊孔型配置方法。同时指出了孔型设计取得的成功经验及改进措施。     

采用6个轨形孔轧制60kg/m钢轨及 UIC60轨孔型设计

6个轨形孔轧制重轨,是重轨断面尺寸稳定的成功经验.本文介绍了轨梁厂研制和其孔型设计,及达到的理想效果.并且初步设汁了国际标准重轨UIC60的孔型.     

Determination of Forward Slip Coefficient During Heavy Rail Rolling Using Universal Mill

The forward slip coefficient is one of the most important parameters for heavy rail rolling using universal mill.For simplifying the theoretical model,the vertical roll with box pass was simplified as an equivalent flat roll first.Second,the neutral angle of horizontal roll and vertical roll was represented.Then,the equation of neutral line on the flank of horizontal roll was determined and the forward slip coefficient of the web was derived according to different positions of neutral line.Finally,the forward slip coefficient of the top and base of heavy rail was obtained.The theoretical results were basically in agreement with the experimental data.     

用热定径一定向预弯法轧制高精度高平直度重轨

为了适应铁路提速和高速铁路建设对重轨尺寸精度和平直度的要求，研究了在热定径的同时，利用辊径差和压下量差对重轨进行定向且弯曲量可控的预弯轧法。试验结果表明，该方法可以明显提高重轨轨高的尺寸精度和全长平直度，且进入矫直机之前重轨的弯曲很小，避免了对矫直辊的冲击，矫直咬入平稳。     

3D Thermo-mechanical Coupled Simulation of Whole Rolling Process for 60kg/m Heavy Rail

3D thermo-meehanical coupled simulation of whole rolling process for 60 kg/m heavy rail was accomplished by FEM method. The finite element model, physical parameters of U75V and parameter setting of simulation were introduced in detail. The whole rolling process of 60 kg/m heavy rail was divided into 27 time cells to simulate respectively, and the model rebuilding and temperature inheritance method in intermediate pass were proceeded. Then, based on simulation results, the workpiece deformation result, metal flow, stress and strain of 60 kg/m heavy rail for typical passes were obtained. The temperature variation curves of whole rolling process for section key points of 60 kg/m heavy rail were plotted, and the temperature falling law of whole rolling process for 60 kg/m heavy rail was studied. In addition, temperature distribution of 60 kg/m heavy rail after whole rolling process was analyzed, and the results showed that temperature was highest at center of rail head and lowest at fringe of rail base. Moreover, the simulation results and measured results of rolling force for 60 kg/m heavy rail were compared, and the regularity was in good agreement.     

Theoretical and Experimental Research on the Rolling Force in Rail Hot Rolling by Universal Mill

 In rail rolling by universal mill, a simplified 3-dimention theoretical model has been built firstly. The kinematically admissible velocity field of the web, head and base of rail have been determined respectively, moreover the corresponding strain rate field and the strength of shear strain rate have been also obtained. Then the plastic deformation power of corresponding deformation zone, the powers consumed on the velocity discontinuity surface and the powers generated for backward slip and forward slip have been proposed. According to the upper-bound method, the roll force of horizontal roll and two vertical rolls can be obtained. Moreover, The process of 18kg/m light rail and 60kg/m heavy rail universal rolling have been simulated by rigid-plastic FEM(finite element method) for verifying the theoretical model. And the universal rolling experiments of 18kg/m light rail has been accomplished in Yanshan University Rolling Laboratory. Compared the results of numerical simulation and the experimental data, the roll force from upper-bound method is somewhat greater than experimental data but in general do not exceed them by 20 percent. So, it is reliable and feasible to preset and optimize the parameter of rolling technology according to the upper-bound method.     

轧制变形对重轨脱碳深度的影响

钢厂轧制U75V钢(%:0.71～0.80C、0.50～0.80Si、0.70～1.05Mn、0.04～0.12V、0.23Cu)60 kg/m重轨的铸坯尺寸为380 mm×280 mm,经第2架粗轧后坯料的断面面积为18 015 mm²。通过轧制变形试验和显微镜观察测试,结合生产现场技术参数建立了有限元模型,以研究分析轧制变形对脱碳层影响。得出经第1粗轧机架和第2粗轧机架孔型轧制后,轨头脱碳层从1.2mm降至0.53 mm,轨腰脱碳层从1.5 mm降至0.54 mm,轨底脱碳层从1.5 mm降至0.83 mm。实测成品轨头的脱碳层为0.2 mm。     

连铸坯轧重轨的压缩比及帽形孔和切深孔的应力场分析

对某厂所使用的重轨孔型自切深孔以后的轧件压缩比进行了分析，对帽形孔和切深孔中沿轧件横断面上的应力场分布进行了弹塑性有限元计算机模拟。结果表明，用连铸坯取代初轧坯，如果坯形和孔形不进行相应的改变，轧件轨头和轨底的压缩比小，难以确保重轨的质量。现有的孔型，沿轧件的横断面上，局部位置存在着较大的拉应力。使用初轧坯，这种拉应力对产品质量的影响不大。但对于连铸坯，如果坯形和孔型均与初轧坯相同，轧件有产生内部缺陷的条件。