简形件强力内旋压有限元模拟

采用动态显式有限元程序LS-DYNA3D对强力内旋压变形过程进行了数值模拟,并对有限元建模提出了一些自己的看法.分析了毛坯周向、轴向、径向的应力应变分布及变化过程,对强力内旋压变形过程建立了整体的认识.分析了工艺参数不合理时产生内表面裂纹的主要原因.     

筒形件强力旋压有限元模拟研究

筒形件强力旋压是一种连续的局部复杂变形过程。采用动态显式有限元程序LS-DY-NA3D对筒形件强力旋压进行了三维有限元模拟,对有限元建模关键问题进行了研究,通过试验验证了有限元模型的合理性。以旋压力和最大等效应力为研究对象,研究了工艺参数和模型参数对模拟结果的影响。模拟结果和实验结果具有较好的一致性。     

ANSYS软件在旋压机设备设计中的应用

采用仿真软件ANSYS对旋压管管口的受力变形情况进行有限元分析,通过建模、加载求解等过程,得到旋压管的受力变形图及工作载荷,为旋压机设备设计提供参数依据,这样可以减少设计成本及周期。     

药筒旋压变形工艺参数选取分析

旋压工艺参数的确定是强力旋压加工的一个关键因素。各种工艺参数的确定、各工艺参数之间如何合理配合以及它们对旋压质量的综合影响都是需要解决的难题,根据实际经验以及旋压仿真模拟结果进行比较,对旋压变形关键工艺参数的选取进行了分析和确定。     

双金属复合管旋压成形力学原理及有限元分析

基于弹塑性力学理论,阐述了双金属复合管旋压成形过程的力学原理,并获得旋压过程中内外管之间残余接触压力最大时的最优径向应力P i*、压头直径D以及进给率f。根据内管外壁和外管内壁周向应变的变形协调关系,确定径向应力P i*和残余接触压力P rc之间的关系。在计算出的理论参数条件下,采用非线性有限元分析软件Abaqus对复合管旋压成形过程进行模拟,模拟结果表明理论分析的准确性,从而为实际生产提供理论参数依据。     

双金属复合管旋压成形力学原理及有限元分析

基于弹塑性力学理论,阐述了双金属复合管旋压成形过程的力学原理,并获得旋压过程中内外管之间残余接触压力最大时的最优径向应力P i*、压头直径D以及进给率f。根据内管外壁和外管内壁周向应变的变形协调关系,确定径向应力P i*和残余接触压力P rc之间的关系。在计算出的理论参数条件下,采用非线性有限元分析软件Abaqus对复合管旋压成形过程进行模拟,模拟结果表明理论分析的准确性,从而为实际生产提供理论参数依据。     

薄壁筒形件错距强力旋压成形的工艺研究

通过双旋轮错距强力旋压成形薄壁筒形件的工艺研究,对错距旋压过程中旋轮轴向错距值的选择、进给比、冷却、润滑进行了讨论,对旋压缺陷进行了分析,解决了旋压过程中出现的问题,达到了工件质量要求。     

筒形件旋压数值模拟及工艺参数优化

本文采用ANSYS／LS—DYNA显式块单元,映射网格划分实体模型,同时也使用了一些有效的加载和处理边界条件的方法,从实际出发建立力学模型对筒形件强力旋压进行弹塑性有限元模拟,分析不同旋轮结构参数对旋压过程中应力应变的影响,对实际生产中优化工艺参数,提高产品质量提供了有力的依据。     

多V型皮带轮旋压成形过程的有限元分析

基于动力显式有限元软件,以电磁离合器皮带轮为侧,开展了两个工序的旋压成形工艺的数值模拟,研究了旋压成形过程中材料变形情况,对成形件的应力应变分布进行了分析。模拟结果表明：采用旋压成形工艺,通过设置合理的进给量、芯模转速等参数,成形出的零件不仅形状和尺寸满足要求,而且芯模和旋轮所受载荷不大,旋轮最大载荷为540kN,芯模最大载荷为19kN。该研究对旋压带轮的非线性有限元分析和实际生产中设备的选择具有一定的参考和实用价值。     

整体式外圈自润滑关节轴承旋压成形工艺探究

自润滑关节轴承的成形及装配工艺是近年来的热门研究课题。针对旋压成形外圈试验,研究旋压成形试验中内外圈存在较大间隙的原因;探索减小旋压成形产生较大间隙的方法;探究旋压成形方法是否可提高成形加工后内外圈间隙的均匀性同时降低对内圈和衬垫的损伤。使用有限元分析软件LS-DYNA,结合弹塑性力学相关理论及旋压成形变形均匀、成形力小以及易于控制的优点,通过分别优化外圈毛坯及旋轮轮廓曲线,进行旋压整体式外圈自润滑关节轴承的工艺探究。     

MECHANISM RESEARCH FOR 3D NON-AXISYMMETRIC THIN-WALL TUBE OFFSET SPINNING

Difference of offset spinning with conventional symmetric spinning is analyzed. A 3D FEM model for offset tube neck-spinning is established and the spinning process is simulated by means of ANSYS software. Dynamic boundary and contact problems in simulation are solved. Transient stress distribution of contact area, transient strain distribution of nodes in typical section and strain distribution of the workpiece at last are attained, the place and the cause of crack are analyzed. Strain variation curves with time of offset spinning and conventional spinning are compared. It shows the mechanism difference between offset spinning and conventional spinning. In addition, simulation results show how strain distribution of typical section, thickness of some typical nodes, axial extension in left section and force of three rollers change with time. According to the study of the variation curve, material flow law along radial, tangential and axial direction is attained and the whole spinning process is studied. The simulation results discover that offset distance is the key to manufacture offset non-symmetric tube, and process parameters change with spinning angle. Experiment data really reflect different process parameters' influence on conventional symmetric and offset spinning force. Experiments accord well with simulation.     

基于ANSYS技术的铜管空拔过程数值模拟分析

为优化铜管空拔工艺参数和提高工件加工质量,应用大型有限元分析软件ANSYS中的LS-DYNA求解器模拟了某规格铜管的空拔成形过程,得到了管件成形过程中任一时刻主要场量的分布云图,分析了成形过程中管件的变形和应力的特点,研究了摩擦力和模具锥角等因素对空拔力与管件伸长率的影响规律。数值模拟分析表明:在应变分布上,管件轴向和周向的最大塑性变形主要发生在管件与模具初始接触处与减径区;在应力分布上,轴向应力和径向应力随管件在模具中的位置不同而有较大差异,在壁厚方向上由管件的外表面到内表面其应力依次为拉应力和压应力,且最大压应力出现在减径区,而最大拉应力则出现在定径区连接处。在管件拉拔力的变化规律上,降低摩擦力和合理的模具锥角能使拉拔力控制在最小范围内。在管件伸长率的变化规律上,较大的摩擦力和模具锥角能使管件的伸长率增大。     

倾斜管件多道次缩径旋压成形的数值模拟及试验

以6061T1(退火态)铝合金为研究对象,以MSC.MARC软件为分析手段,采取有限元法对三维非轴对称倾斜管件多道次缩径旋压过程进行数值模拟,并利用网格圆及显微组织的变化从试验的角度验证模拟所得到的应变分布规律。结果表明,倾斜使得工件的应力应变呈不均匀分布规律;等效应力沿轴向呈分层分布的特点,在口部达到最大值;等效应变沿周向0°～180°域逐渐减小,在0°域存在最大值,180°域存在最小值;沿轴向从起旋处到口部,等效应变在0°域具有逐渐增大和在180°域具有逐渐减小的特征。由于返程旋压的明显增厚效应,多道次旋压时,工件变形中间部位壁厚增加。多道次缩径旋压时工件变形中间部位壁厚变化规律的试验结果与模拟结果的相对误差不大于10%,说明所建立的有限元模型是合理可靠的。在理论分析及试验研究的基础上,成功研制出倾斜类汽车排气歧管样件。     

ANALYSIS OF MECHANICS IN BALL SPINNING OF THIN-WALLED TUBE

Ball spinning is applied to manufacturing thin-walled tube with high precision and high mechanical properties. On the basis of plastic mechanics, by simplifying ball spinning of thin-walled tube as plane strain problem, slab method is used for the purpose of calculating the contact deformation pressure. The spinning force components, the torsional moment, the deformation power and the deformation work are calculated further as well. The influence of the two important process parameters such as the feed ratio and the ball diameter on the spinning force components is analyzed in order to further control the spinning force components by regulating the two process variables during the ball spinning process. The stress and strain state in deformable zone as well as mechanics boundary conditions in ball spinning are obtained. The effect of the three spinning force components on the formability of the spun part is analyzed and validated through the ball spinning experiments. The theoretical and experimental results show that the radial spinning component plays a significant role in ball spinning of thin-walled tube, and the mechanics situation in backward ball spinning contributes to enhancing the plasticity of the metal material, but that in forward ball spinning contributes to advancing the axial flow of the metal material.     

微张力减径过程热力耦合有限元模拟

根据某厂十机架微张力减径机组轧制工艺,采用大变形弹塑性有限元法建立了管坯连轧三维热力耦合计算模型,并对实际工艺过程进行数值计算,得到了连轧过程中轧件的温度场、应变场和应力场分布规律。基于计算结果,分析了管坯壁厚分布规律、机架力能参数分布。所得结果与现场设定、实测结果吻合良好,表明了该计算模型的有效性。该模型可为现场张力减径工艺过程离线分析提供有力帮助。     

Finite element analysis on neck-spinning process of tube at elevated temperature

Tube spinning process is a metal forming process used in the manufacture of axisymmetric products and has been widely used in various applications. Finite element analysis has been successfully applied to the tube spinning processes, but no temperature effects have been considered on neck-spinning. For this reason, the aim of this research is to investigate numerically the neck-spinning process of a tube at elevated temperature. The commercial software Abaqus/Explicit was adopted in the simulation. For the construction of the material model, special uniaxial tensile tests were conducted at elevated temperature and various strain rates, since the material is sensitive to strain rates at high temperature. Comparisons between experimental and simulation results on thickness distribution and the outer contour of the spun tube are discussed. During the final stage, the average deviations between the simulation and experiment were 10.65% in thickness and 3.03% in outer contour. Good agreement was found between experimental and simulation results. The influence of the coefficient of friction, roller translation speeds, and the tip radius of the rollers were also investigated through numerical simulation.     

Study on compound spinning technology of large thin-walled parts with ring inner ribs and curvilinear generatrix

Given their rapid development, aerospace and other high-tech industries are in urgent need of process technology for large complex thin-walled shells represented by large thin-walled parts with ring inner ribs and curvilinear generatrix. To make up for the deficiency in existing forming methods, this paper presents a compound spinning process that integrates counter-roller spinning, multi-neck spinning, and hot spinning. The finite element models for the counter-roller spinning and multi-neck spinning forming of such parts are established, and these models can simulate the influences of different spinning process parameters on workpiece maximum equivalent stress and maximum ovality. The 2A12 aluminum alloy tube blank is used in this paper. The process parameters for obtaining the counter-roller spinning for such parts are as follows: a feed ratio of 1.0 mm/r and a roller nose radius of 8 mm. The process parameters of multi-neck spinning are as follows: a feed ratio of 3.0 mm/r and a roller nose radius of 80 mm; and the forming temperature of hot spinning is 200–250 °C. Verification by a compound spinning test found that the numerical simulation results are consistent with the process test results. The process parameters can be used for guiding the actual production of large thin-walled parts with ring inner ribs and curvilinear generatrix.     

Plastic Deformation Mechanism in Double-Roller Clamping Spinning of Flanged Thin-Walled Cylinder

Double?roller clamping spinning(DRCS) is a new process for forming a thin?walled cylinder with a complex surface flange. The process requires a small spinning force,and can visibly improve forming quality and production e ciency. However,the deformation mechanism of the process has not been completely understood. Therefore,both a finite element numerical simulation and experimental research on the DRCS process are carried out. The results show that both radial force and axial force dominate the forming process of DRCS. The deformation area elongates along the radial direction and bends along the axial direction under the action of the two forces. Both the outer edge and round corner of the flange show the tangential tensile stress and radial compressive stress. The middle region shows tensile tangential stress and radial stress,while the inner edge shows compressive tangential stress and radial stress. Tan?gential tensile strain causes a wall thickness reduction in the outer edge and middle regions of the flange. The large compressive thickness strain causes material accumulation and thus,an increase in the wall thickness of the round corner. Because of bending deformation,the round corner shows a large radial tensile strain in addition. The inner edge of the flange shows small radial compressive strain and tensile strain in thickness. Thus,the wall thickness on the inner edge of the flange continues to increase,although the increment is small. Furthermore,microstructure analysis and tensile test results show that the flanged thin?walled cylinder formed by DRCS has good mechanical properties. The results provide instructions for the application of the DRCS process.