数值模拟在极限规格H型钢工艺优化中的应用

针对HW150mm×150mm极限规格H型钢产品偏心问题,采用有限元方法对粗轧阶段孔型系统进行三维热力耦合数值模拟。基于模拟结果分析金属流动、塑性应变及温度变化,以此为基础,根据变形特点及各孔型轧件尺寸分析偏心产生的原因,优化孔型并进行验证,最后进行现场实践,排除缺陷。结果表明,有限元模拟有助于分析轧制过程中的金属成形,尤其对于型钢轧制过程中的变形规律及缺陷分析具有较高的参考价值和指导意义。     

Experiment and Simulation of Metal Flow in Multi-stage Forming Process of Railway Wheel

To investigate the metal flow during the railway wheel forming process,experiments and finite element method(FEM)simulation were carried out.An axisymmetric modeling for the wheel rolling process was proposed to predict the metal flow in radial direction,by which the whole multi-stage forming process could be simulated in axisymmetric and integral way.The result shows that the axisymmetric simulation method was an effective method to explore the metal flow in radial direction and to analyze the relationships of tools motion during the wheel rolling.The detail information about metal flow in railway wheel forming process was obtained.The metal in the wheel web was from the area near the half radius of the original billet;the chill zone of the billet became an envelope of the rim and part of the web with a maximum thickness of about 6mm below the tread.At the wheel rolling stage,the metal in the rim flowed towards the web;the metal near the surfaces of the conjunction region between the web and rim suffered severe shear deformation.     

TC4合金锥体模锻过程的数值模拟

采用刚塑性有限元法对钛合金锥体的模锻成形进行有限元数值模拟,分析了锥形件模锻过程中的金属流动规律,应力场、应变场、变形区的压力分布,压力的变化规律等。模拟结果表明,锥体模锻成形分为3个阶段:初期变形过程是圆柱体变形为一个小曲率壳体的阶段,应力主要集中在上模的正下方,应变主要发生在此变形区;变形中期是与下模相接触的部分参与变形的体积逐渐增大,直至最后形成所需要的锥体形状;变形后期由于摩擦作用产生严重的不均匀壁厚减薄现象。     

斜轧螺纹过程的数值模拟

对螺旋孔型斜轧螺纹过程进行了非线性有限元分析，得到了轧件内部应力－应变分布情况，为模具的设计和工艺参数的确定提供了重要依据。     

风管共板法兰辊弯成形过程的有限元仿真

利用通用非线性的ABAQUS软件对多道次辊弯成形过程进行建模以及数值模拟,对辊弯成形工艺及成形规律进行了研究,为辊弯成形的工程设计、工艺参数和辊弯设备的调整提供了科学的依据。整个辊弯成形过程基于动力显式算法,建立风管共板法兰多道次辊弯成形的有限元模型。其中涉及了辊弯成形的模型建立、单元选择、边界条件、有效速度质量放大系数的选择等辊弯成形的一般性问题解决方法。     

铜材接触线扩展挤压成形的三维有限元数值模拟

根据有限变形刚粘塑性有限元理论,基于DEFORM-3D软件平台,对接触线在模腔中扩展挤压成形过程进行了三维有限元数值模拟,获得了扩展挤压成形过程的应力场、应变场、温度场和速度场分布,并揭示了金属流动规律,从而为模具设计提供理论依据。     

材料各向异性对板料拉延成形的影响

文章用刚塑性有限元法,开发了一个二维数值模拟程序系统,以厚向异性、平面异性为条件,对圆筒件拉延成形中的法兰变形区进行了数值模拟,给出了法兰变形区的金属流动规律。     

有限元法在板材热轧中的应用

采用弹塑性大变形热力耦合有限元法研究板材热轧过程．利用有限元理论建立了板材热轧模型；应用MSC／MARC软件进行计算，重点分析了轧制过程和变形区中轧件的温度场分布和变化、金属的流动、应力应变的变化趋势，以及轧制力的变化情况．计算结果与实际生产情况相吻合，同时表明有限元理论可以实现对板材热轧过程的数值模拟．     

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.     

Nonlinear Finite Element Analysis of Thin Strip Temper Rolling Process

 To reveal the basic deformation mechanisms under the conditions of high friction, small reduction, and long contact length in thin strip temper rolling process, an elastoplastic finite element analysis of plane strain upsetting was made based on the FEM software Marc. The results indicated that a near flat ‘zero reduction’ region was present in the center of the contact arc. The simulation results about the effect of rolling parameters on the central flat region showed that any change of increasing the rolling force could result in or enlarge the central flat region in the deformation zone. Stress distribution results illustrated that the metal was in triaxial compression state. Although the maximum and minimum principal stresses were all much larger than the yield stress of the strip, the equivalent stress became lower than that, and no further plastic strain, even a small elastic spring back occurred in the central flat region. That was the problem of ‘hydrostatic pressure’ in thin strip temper rolling.     

圆管二次辊弯成形过程中的大变形有限元法模拟

应用弹塑性三维大变形有限元理论，同时考虑材料和几何双重非线性，基于Ｐｒａｎｄｔｌ－Ｒｅｕｓｓ流动规律和Ｍｉｓｓ屈服准则，并采用Ｕｐｄａｔｅｄ－Ｌａｒｇｒａｎｇｉａｎ增量叠加法分析了不同压下量成形过程中金属由非稳态到稳态的流动规律，然后通过有限元程序实现了计算机模拟。模拟结果为ＣＡＤ（计算机辅助设计）及ＣＡＭ（计算机辅助制造提供了重要理论依据，同时还可以指导实际生产过程，对提高产品的质量和经济效益有     

Analysis of Metal Forming in Two-Roll Cross Wedge Rolling Process Using Finite Element Method

A simulation model for two-roll cross wedge rolling (CWR) was presented by using three-dimensional rigid-plastic finite element method (FEM).The whole forming process of CWR,including knifing zone,guiding zone,stretching zone,and sizing zone,was simulated using the model in which dynamic adaptive remeshing technology for tetrahedral solid elements was used to fix element distortion.Based on the simulation results,the distributions of metal flow field,strain field,and damage field,and the geometry of the workpiece's end were analyzed.These results could provide theoretical guidance for realizing net shaping and reasonable design of tools.     

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。     

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。     

Elastic‐Plastic Finite Element Analysis of Sheet Rolling Using Co‐Rotational Formulation

A new elastic‐plastic finite element analysis for rolling processes is proposed. This analysis is based on a co‐rotational formulation with finite deformation theory. It enables to perform an accurate characterization of the rolling process in a short computation time, as it allows a large increment in plastic strain and the direct implementation of the neutral point into the analysis. The basic mathematical formulation of the proposed analytical model is described first, and its application to the simulation of sheet rolling with large and small thickness reductions is presented. Through this investigation, it has become clear that the proposed model is capable of analysing the elastic‐plastic deformation characteristics of a sheet under rolling, which is indispensable for the design of a rolling process for the manufacture of sheets with accurate flatness and profile.     

Analysis and Simulation of Parallel Tubular Channel Angular Pressing of Al 5083 Tube

Severe plastic deformation (SPD) is divided to a number of branches. One of the most important branches of SPD of tube materials is parallel tubular channel angular pressing (PTCAP). The PTCAP process is more complicated than another SPD process for metal tubes. The PTCAP process includes two half cycles for obtaining the desired product. There are some factors, which affect the PTCAP process. For instance, deformation ratio, clamping force, channel angles, and curvature angles. In this paper, the PTCAP process for aluminum alloy (Al 5083) was simulated through the finite element ABAQUS software in order to investigate the effect of die parameters. Thus, the influences of deformation ratio, channel angles, and curvature angles on the PTCAP process were examined numerically. In addition, to verify the finite element method (FEM) results, the PTCAP process was done experimentally. To some extent, good conformity was observed between the FEM calculations and experimental results.     

A finite element method on the basis of texture components for fast predictions of anisotropic forming operations

This paper introduces a novel method of including and updating texture‐based elastic‐plastic anisotropy during large‐strain metal forming operations. The approach is particularly designed for industrial use since it can be assembled by integrating existing software solutions from crystallography and variational mathematics. The approach is based on feeding spherical crystallographic texture components directly into a non‐linear finite element model. The method is used to perform fast simulations of industrial‐scale metal forming operations of textured polycrystalline materials including texture update. Instead of yield surface concepts or large sets of discrete grain orientations, a small set of discrete and mathematically compact Gaussian texture components was used to map the orientation distribution function discretely onto the integration points of a viscoplastic crystal plasticity finite element model. This method drastically enhances the computing speed and precision compared to previous crystal plasticity finite element approaches. The publication gives a brief overview of the different anisotropy concepts, provides an introduction to the new texture component crystal plasticity finite element method, and presents examples.     

Coupling Thermomechanical and Microstructural FE Analysis in Plate Rolling Process

Using three-dimensional rigid-viscoplastic finite element method （FEM）, a coupling multivariable numerical simulation model for steel plate rolling has been established based on the physical metallurgy microstructural evolution rule and experiential equations. The effects of reduction, deformation temperature, and rolling speed on the deformation parameters and microstructure in plate rolling were investigated using the model. After a typical rolling process of steel plate 16Mn is simulated, the strain, temperature, and microstructure distributions are presented, as well as the ferrite grain transformation during the period of cooling. By comparing the calculated ferrite grain sizes with measured ones, the model is validated.     

FEM Simulation of Large Diameter Pipe Bending Using Local Heating

 With the aid of elastic plastic large deformation finite element method (FEM), an elastic plastic and coupling thermo mechanical model was built to calculate the bending process of the bent pipe, combining with local heating or cooling of the bent pipe. Based on the FEM simulation, the metal deformation during the bending process was analyzed in detail. The thinning and thickening ratio of the pipe wall thickness, the ovality of the cross section of the pipe and the spring back angle, etc, are presented.     

连铸板坯矫直过程应力应变的有限元模拟

采用弹塑性有限元分析法,对拉速1.0m/min、厚度230mm的板坯,在3套不同的辊列布置的单点矫直、四点矫直、连续矫直进行应力应变的有限元模拟。结果表明:铸坯等效VonMises应力值和铸坯水平方向应力按单点矫直、四点矫直、连续矫直依次减小;与单点矫直相比,四点矫直减小了每次矫直的变形量和应变速率;连续矫直时,在变形区内等效应变沿长度方向呈线性变化,最大值为1.11%,等效塑性应变速率较低,约为5.5×10^-5s^-1,其应变速率最低,是比较理想的矫直方式。