Dimensional analysis in steel rod rolling for different types of grooves

Sequence design for shape-rolling processes consists of roll pass and profile design, i.e., transforming the billet into a final shape. For the prediction of the mean effective strain of the workpiece during rod rolling, an analytical model by Shinokura and Takai was used. They verified the formula by applying it to a variety of rod-rolling geometries (oval-square, oval-round, square diamond, and diamond-diamond). Today, on the other hand, the finite element (FE) techniques allow analysis of rolling processes in such a way as to simplify the work of design engineers. In this study, a round-oval pass and a round-flat oval pass are analyzed for steel rod rolling. In particular, the analysis of the spread, the surface profile, and cross-sectional area of the workpiece were conducted during rolling. Experimental data such as the maximum spread and the radius are compared with the results of the analytical model and FE analysis.     

三辊行星轧制中轧辊与轧件接触区分布

三辊行星轧制中,轧辊轧件接触区的分布是轧制力和轧制功率计算的基础,是轧辊外轮廓设计的重要依据.研究结合了实际轧制过程中轧辊和轧件的运动特点,引入相应的约束条件,给出接触区分布的解析表达式;在给定轧制工艺参数下,数值分析计算出接触区具体的分布情况.该方法避开了轧辊轧件线接触的假设,可给出接触区分布情况.结果显示,该分布不...     

板带轧制过程的三维耦合有限元分析

对板带轧制过程进行严密的三维分析是研究轧制参数对轧后板带尺寸、板形和机械性能的影响 ,从而实施有效控制的基础。本文简要回顾了板带轧制过程三维数值模拟的研究进展 ,提出了一个分析板带轧制过程的耦合有限元模型 ,其中 ,轧件塑性变形采用刚塑性有限元法计算 ,辊系弹性变形采用弹性有限元法计算。计算实践表明 ,该模型具有良好的精度和较高的效率。     

斜轧钢球辊形曲面分析研究

首次提出将斜轧钢球轧辊的转动与轧件的轴秘移动分开考虑，用画法几何中的图形变换法与微分几何中的包络法分别求出斜轧钢球轧辊轧形曲面的图解解与解析解。进一步分析结果表明，从理论上完整地描述斜轧钢球轧辊辊形曲面仅需要四个独立坐标。     

棒材轧制轧件出口断面形状预测及平均轧辊半径的新计算模型

对圆—椭圆—圆孔型轧制合金钢,提出了接触边界临界点的概念,建立了出口断面形状预测模型,推导出临界点的解和新的等效接触断面面积公式,给出了计算平均轧辊半径的新模型。为验证新模型,完成了棒材轧制试验,并且利用刚塑性有限元法对轧制过程进行了模拟。将不同模型得到的理论结果与实验值和模拟值作比较,证明新模型具有很高的精度,因此可以用于精轧孔型设计和轧制工艺参数的设定。     

三辊行星轧制运动和管坯变形规律的仿真模拟

应用弹塑性大变形有限元法,对连铸铜管坯三辊行星轧制过程进行了三维有限元模拟研究。通过坐标变换的方法建立了三辊行星轧制有限元模型,该模型考虑了轧辊的倾斜角β和偏转角α。模拟分析得出三辊行星轧制过程中管坯断面要经受一个由圆形到三角形再归到圆形的变形过程。得出在三辊行星轧制过程中起到主要作用的是三向压应力状态,有利于坯料的大变形和提高轧制管材性能。同时模拟分析得到三辊行星轧制过程中坯料质点的运动轨迹和相应规律。该模拟计算对探索复杂的三辊行星轧制规律具有重要意义。     

Analytical and experimental study on the spiral marks of the rolled product during three-roll planetary rolling processes

In this study, the effects of various rolling conditions, such as inclined angle, offset angle, roll shapes, etc., upon the depth of the spiral marks on the surface of the rolled product and the rolling forces are discussed numerically by the finite element method. Experiments using a self-designed testing machine with work-rolls of three different kinds of roll shapes were conducted. The depth of the spiral marks was measured. From the comparisons between the analytical and experimental results, it is known that a smoother surface on the rolled product can always be obtained with convex-shaped rolls. Whereas, prominent spiral marks probably appear for two-stage conical rolls and spherical-headed rolls under an ill-set rolling condition. These analytical and experimental results can offer useful knowledge for the design of the roll shapes and the pass schedule during three-roll planetary rolling processes.     

Analysis of Mechanical Parameters during Hot Continuous Rolling Process of Titanium Alloy TC11 Rod

将Ф25 mm 的 TC11 钛合金棒材在四机架 Y 型轧机上连轧至Ф17 mm,孔型系统选为平三角-圆-平三角-圆。试验测试了轧件入口温度为 950 ℃时在四机架连轧过程中的温降,以及轧件温度为 750, 850, 950, 1050 ℃时不同压下量对应的轧制力、轧制力矩值;分析了轧件在不同孔型中轧制时的变形区几何形状;修正了轧制力数学模型;计算值与试验值偏差较小。因此,该数学模型计算的轧制力可以为 Y 型三辊轧制钛合金棒材提供理论研究和工程实践基础。     

FEM analysis for V–H rolling process by updating geometric method

Three passes of slab rolling during vertical–horizontal rolling process were simulated with explicit dynamic FEM by updating geometric method. Simulation model of the next pass was built when the rolling geometry model was updated after previous pass was finished, changing roll gap, material attribution and boundary conditions. The calculated results of the slab shape are in good agreement with the experimental ones. It is shown that the explicit dynamic FEM and updating geometric method can be used effectively to analyze the multi-passes of V–H rolling process.     

驱动辊转速对环件轧制工艺影响规律研究

针对环件轧制成形规律,以数值仿真和数学解析相结合的方法,以有限元分析软件ABAQUS为平台,建立弹塑性动态显式有限元模型,研究驱动辊转速对环件成形工艺的影响。研究表明,在环件轧制过程中,随着驱动辊转速的增加,每转进给量减小,外径部分金属轴向流动增加,环件自由端面形状系数FT增加,最大宽展系数增加,环件自由端面质量下降;在驱动辊转速增加过程中,轧制力和轧制力矩减小,对轧环机的力学性能要求降低。同时平均等效应变PEEQa增加,环件塑性变形程度增大,有利于提高环件力学性能,但同时变形不均匀程度也加大,内部质量缺陷的可能性增加。     

滚压有限元模型数值模拟

滚压数值模拟是制定滚压工艺、预测滚压后工件表面残余应力分布,以及判定工件疲劳性能的重要工具。目前的滚压数值模拟主要集中在对曲轴以及回转体的分析,少有的对平面滚压数值模拟中,大多数也只分析了单圈或不到一圈的滚压过程,而且与实际滚压工艺存在较大的区别。为弥补以上不足,该文采用有限元商业软件ABAQUS提供的Explicit模块,并结合python编程语言,开发了更接近于实际的滚压模拟过程;采用该模型研究了滚压力的大小、滚针直径、表面摩擦系数等对于残余应力分布规律的影响,并通过H13钢的滚压实验,对模型模拟结果进行了验证。     

水平上调式三辊卷板机卷圆成形控制系统设计

针对目前三辊卷板机由于液压系统驱动导致的定位精度低、卷圆精度不高、运行过程不稳定等问题,在三辊卷圆成形工艺及水平上调式三辊卷板机结构的基础上,建立下辊上升量与卷制半径、板材厚度与材料属性之间的数学模型。利用该数学模型及光栅尺反馈的下辊位置,建立了下辊定位闭环系统,开发了以西门子S7-1200为主控制器的控制系统。试验结果证明:该控制系统实现了对下辊定位的精确控制,通过伺服电机驱动下辊升降提高了卷圆的成形精度及工作效率。     

Spread Model for TC4 Alloy Rod during the Three-Roll Tandem Rolling Process

为了保证三辊连轧过程中棒材的成型精度,研究了TC4钛合金棒材的宽展。采用正交试验优化设计方法设计数值模拟方案,在Marc有限元平台上,研究轧制工艺参数(轧制温度、轧制速度、孔型内切圆直径、轧辊直径、摩擦系数)对宽展的影响,并分析了各参数的影响显著性顺序。在此基础上,建立了三辊轧制TC4棒材的宽展模型。试验在自行研制的8机架Y型连轧机上进行,孔型系统为平三角-圆。宽展测量结果和模型计算结果吻合较好。     

立辊辊槽磨损对板坯断面形状的影响

针对热连轧粗轧段板坯在线调宽生产中立辊辊槽的磨损对轧制后板坯截面“狗骨”形状的影响,本文基于弹塑性有限元理论,利用有限元软件MSC．Marc,对在不同侧压量下,采用新立辊、磨损中、磨损后立辊和磨损的理想极限平立辊四种轧制条件下对应的板坯截面形状变化进行了仿真分析。得出了立辊辊槽磨损对“狗骨”形状的影响规律,随着磨损加深,立辊辊槽宽度增大,“狗骨”形状明显。     

楔横轧轧件端头凹心影响因素的研究

用ANSYS／LS－DYNA软件对楔横轧轧制过程进行非线性有限元模拟，得到轧件端头凹心的形成原因，总结出模具成形角、展宽角、轧件端头尺寸及轧细长度等因素对轧件端头凹心大小的影响，并将计算结果与实验结果进行比较，其规律一致。本研究对合理确定楔横轧工艺参数、提高材料利用率具有重要的意义。     

FE simulation and experimental research on cylindrical ring rolling

During the conventional ring rolling process, the ring mainly produces the incremental deformation of wall-thickness reduction and diameter expansion, which makes it difficult to manufacture the cylindrical ring with small diameter and large height. In this paper, a new method for manufacturing the cylindrical ring using a ring blank with smaller height, i.e. cylindrical ring rolling, is proposed and its feasibility is verified. For evaluating the cylindrical ring rolling process and to better understanding its deformation characteristics, a 3D elastic–plastic FE model of cylindrical ring rolling is first established. Then, the comparison between conventional ring rolling and cylindrical ring rolling is investigated using this 3D FE model. Finally, the effects of the process parameters, such as the feed rate of the idle roll, diameter of the idle roll and friction coefficient between the rolls and ring, on cylindrical ring rolling are numerically revealed. The experiment is carried out on a vertical NC ring rolling machine and the good agreements between the experimental and simulation results verify the validity of the established 3D FE model of the cylindrical ring rolling.     

圆-椭圆-圆孔型中轧制合金钢棒材时宽展迭代模型的建立

在预测圆-椭圆-圆孔型中轧制合金钢棒材的宽展时,在Shinokura宽展公式基础上进一步考虑了棒材材质对宽展的影响,并且推导出了轧件出口断面等效高度和轧辊平均工作半径公式,对Shinokura宽展公式进行了修正。为得到更精确的宽展值,基于修正后Shinokura的宽展公式用迭代法建立了宽展迭代模型。为验证宽展迭代模型的有效性,进行了GCr15棒材轧制实验,并用刚塑性有限元法模拟了轧制过程,通过比较认为,此迭代模型收敛速度快,并且具有比较高的精度,能用于棒材精轧孔型设计和轧制工艺参数的设定。     

车轮轧制成形过程的有限元模拟

采用DEFORM-3D建立车轮轧制过程三维有限元分析模型,在建立轧制过程的数学模型和开发轧辊运动的控制算法,并与DEFORM软件集成的基础上,模拟了实际轧制过程中轧辊的运动。从轧制力对比与轮坯几何形状的分析两方面验证了模型和控制算法的可靠性;分析了轧制过程中材料的流动规律,为改进轧制工艺提供了参考。     

Effect of roll gap adjustment on exit cross sectional shape in groove rolling—Experimental and FE analysis

We machined work roll with groove worn down as well as groove with no wear. We then performed a pilot hot rod rolling test at temperature of 1000 °C using plain carbon steel (0.1% C) as the roll gap decreases from reference roll gap (6.5 mm) to 3.5 mm. To understand better the effect of roll gap (i.e., section height) adjustment on the exit cross sectional area (ECSA) variation of workpiece in a two-stand groove rolling process with wear is considered, we carried out a series of three dimensional finite element analysis. Results reveal that variation of ECSA is almost linearly proportional to roll gap change while the roll gap decreases from reference roll gap (6.5 mm) to 3.5 mm. In oval groove rolling, the exit cross sectional shape and area predicted by FEA is in a good agreement with those measured. In round groove rolling, however, some deviations between FEA and experiment are observed because of roll groove geometry coupled with cross sectional shape of incoming workpiece. In the two-stand groove rolling, the effect of roll gap adjustment at each stand on the exit cross section of workpiece is somewhat different, in comparison with single-stand groove rolling. The roll gap adjustment at the previous stand has a more influence on the ECSA of workpiece than that of the next stand.     

An analytical approach to asymmetrical cold strip rolling using the slab method

An analytical model for general asymmetrical cold rolling is proposed to investigate the behavior of sheet during asymmetrical rolling using the slab analysis. Neutral points between the upper and lower rolls and the strip, rolling pressure distribution along the contact interface of the roll and strip, and rolling forces, as well as rolling torque, can be calculated easily using this model. Rolling pressure distribution, rolling force, and rolling torque, which are affected by various rolling conditions such as roll speed ratio, thick-ness reduction, front and back tension, etc., are analyzed. Additionally, the limiting rolling conditions be-tween reduction and roll speed ratio, or front and back tension, under which the rolling process can be accomplished successfully, are discussed. By comparing analytical results and experimental measure-ments of rolling force, it is apparent that the proposed model can successfully provide useful knowledge for designing the pass schedule of the asymmetrical cold strip rolling process.