工作带长度对分流模模芯稳定性的影响研究

对分流模挤压6061铝合金管材进行了有限元模拟分析,研究了工作带长度对模芯稳定性的影响。结果表明,模芯挤压方向的位移会随着工作带长度的增大而增加;而过小或过大的工作带长度均会造成分流模上模出现等效应力的集中分布。根据模拟分析得到了不同直径焊合室适宜的工作带长度。     

基于HyperXtrude铝型材挤压模具设计和模拟分析

本文针对某公司生产的6063铝合金复杂截面工业型材,在分析铝合金型材挤压分流模的各结构要素的基础上,设计了分流挤压模并对模具强度进行了校核;运用Pro/E绘图软件,建立了模具的三维仿真模型;基于HyperXtrude有限元分析软件平台,对该型材的挤压过程进行了模拟仿真分析,获得了挤压过程中型材和模具的温度、应力、变形分布;通过对模拟结果的分析,预测了挤压时可能产生的弯曲、翘曲等缺陷,并对分流孔、工作带以及工艺等进行了优化,使挤压时金属流动更加均匀。     

中空铝型材用半球型组合模

对铝中空型材用挤压模进行试验分析，为提高分流模的使用寿命，把平面分流模改为半球形，模芯和分流桥交叉处的张应力只有舌型模的１／４左右，从而提高了模具的寿命。     

基于数值模拟的连续挤压铝管竹节纹缺陷的成因探讨

本文针对连续挤压本身金属流动不均匀是否会导致挤压铝圆管时出现竹节纹缺陷这一问题进行了数值模拟分析,并对几种均衡金属流速的方案进行了对比研究.通过去掉凹模以解决模拟过程中网格自接触的问题,使模拟过程得以实现.通过对金属在各分流孔流动均匀性判定参数δ的比较得出结论:连续挤压本身的结构特点所造成的变形金属在腔体进料口处所产生的速度差异,不会导致竹节纹缺陷出现;使用具有3个分流孔的分流组合模时,采用通用的铝材连续挤压腔体,并将凸模的一个分流桥放置在靠近堵头的对称面上,是均衡金属流速的最佳方案.     

基于UGNX的铝型材挤压分流模设计

在铝合金空心型材生产时,平面分流模得到广泛的应用。由于模具结构复杂,应用传统的二维模具设计方法建立模具模型,存在很多不足。实体模型是进行有限元分析和优化设计的基础。以LX0349号型材为例,介绍了UGNX在铝材挤压分流模实体建模中的应用,从而为进一步进行有限元分析和模具优化设计打下了基础。     

铝合金双孔挤压模具设计及仿真模拟分析

本文以6063铝合金空心截面型材为例,通过对铝合金型材的分析,结合平面分流组合模各个组件的结构要素、设计要点,设计了双孔挤压模具并校核了模具的强度;在Pro/E绘图软件上建立模具的三维仿真模型;在HyperXtrude有限元分析软件上对三维仿真模型进行了网格划分,设定边界条件和参数,模拟该型材的挤压过程并收集该型材在工作带处的温度分布、流速差异和变形程度等信息。     

基于有限元模拟的双孔挤压分流模具设计

文章以双模孔挤压模具为分析对象,采用有限元分析的方式,以完全相同的挤压工艺参数对两种不同的模具设计进行分析(上模分别设计为4个分流孔和7个分流孔)。结果显示,7个分流孔的模具设计在挤压过程中会增加挤压力,出现模具断裂及堵模的风险。因此,确定4分流孔为最终模具设计方案,并将最终的设计方法引用到实际生产中。     

铝合金车辆大型材模具的设计与制造工艺研究

大型型材挤压模具设计与制造是现代车辆大型铝合金型材生产的关键技术。本文以典型的、难度较大的底版型材GDX—11为例，对大型模具的结构参数和尺寸设计进行了深入分析，并对模具材料及热处理与模具制造工艺和修模等进行了讨论。分析认为轨道车辆大型材多为扁宽、薄壁复杂的空心型材，一般用平面分流模在80／95MN以上的挤压机，用扁挤压筒进行生产。GDX—11型材所选用的模具结构设计方案，模具材料及其热处理工艺，分流孔的大小和形状以及分流桥、模芯、焊合室的结构设计是合理的。模孔尺寸、工作带尺寸以及制模工艺、挤压工艺的确定都是可行的。修模是一道重要的技术工序，对复杂的大型模具更为重要。     

大口径白铜管偏心扩径的数值模拟

基于Deform-3D有限元软件建立了Φ278mm×9.0 mm大口径白铜管的无外模扩径拉拔模型,研究了芯模偏转对扩径管材变形规律及管形和尺寸的影响。结果表明,偏心扩径过程中,应变在管材周向分布不均是由于管材各部分受力不均引起先变形区产生大变形和后变形区产生小变形导致的;随着芯模偏转角度从0°、2°、4°增大到6°,管材的圆度越来越差,壁厚偏心率也逐渐增大。     

冷挤压有限元分析

详细阐述了杯形反挤压成形的冷挤压过程。通过经典理论算法和ANSYS有限元算法，计算出了挤压力的大小。分析比较可以发现：有限元法能获得更高的计算精度。通过ANSYS的求解后处理，分析得出了挤压件的应力应变的分布情况。和挤压阶段时凸模的压力行程曲线。在此基础上，改用不同的材料特性、凸模的形式、润滑条件以及通过APDL参数化设计语言改变挤压件的尺寸大小进行反复求解。从而获得了这些因素对挤压力的影响规律。     

铝型材挤压成型过程有限元模拟及模具优化设计

应用UGNX建立了平面分流组合模的几何模型,利用有限元软件DEFORM-3D对挤压过程进行有限元模拟,研究了挤压铝合金空心型材时金属的流动情况。模拟结果表明,即便是对称性较好的铝合金窗用光企型材（有一个对称轴）模具,按照常规的设计方法也很难避免金属的流速不均问题,影响型材的成型度。对于绝大多数空心型材来说,其断面往往都是不对称的,仅依靠设计者的经验和判断设计模具是很难避免金属流速不均问题的。而采用有限元模拟的方法,则可以及时发现设计中存在的不足,并通过修改设计方案,达到满意的效果,为设计模具提供科学的依据。     

芯棒直径对楔横轧5Cr21Mn9Ni4 N空心气门壁厚均匀性的影响规律

楔横轧空心轴类件存在壁厚分布不均问题,特别是在小直径大长径比空心件楔横轧成形中更为突出.本文在Gleeble-1500D热模拟实验机上进行了5Cr21Mn9Ni4N耐热钢的热压缩实验,得到了5Cr21Mn9Ni4N的热变形本构方程.通过改变芯棒直径,采用有限元仿真和实验相结合的方法,研究了楔横轧轧制空心气门过程中的壁厚变化规律.研究结果表明,带芯棒轧制时,芯棒直径存在临界值,在该值下进行轧制,空心气门预制坯壁厚均匀性最优;楔横轧空心件时,金属轴向均匀流动是壁厚均匀的必要条件;轧件轴向拉应变减小,径向压应变变大,周向应变在0附近且为拉应变时,壁厚较为均匀.      

CONFORM铝连续挤压机主轴系统研究

本文分析了CONFORM连续挤压机主轴系统工作 时的受力情况，主轴受热伸长时在主轴系统产生很大的轴向力，对设备性能影响非常大。设计出一种新型联轴器联接主轴，此联轴器在受很小轴向力的作用时，允许被联接轴作轴向游动，基本消除了轴向力及春对设备性能的影响，此项设计改进已应用于LJ300连续挤压机，效果十分理想。     

Effects of Anisotropy in Drawing and Extrusion Processes of Bulk Metal Forming

The effects of anisotropy of axisymmetric materials (round bars, tubes) on metal forming processes are discussed. These effects are strongest for thin‐walled hollow materials in metal forming processes when the wall thickness is not predetermined by the die (tube drawing without mandrel, free extrusion of hollow components). Similarly to the normal anisotropy of sheet metal, a high radial anisotropy increases the resistance against a variation of wall thickness in tube drawing. There are also effects in forming solid materials such as forward extrusion of bars whereby the buckling of cross sections is influenced through the variation of radial anisotropy with the distance from the axis. The favourable anisotropy properties depend on the actual priorities. If, for example, for a metal forming process the material anisotropy results in high compressive stresses this may be favourable for increasing the ductility of the material whereas the increase of the load acting on the tool reduces tool life.     

Finite-element modeling of nonisothermal equal-channel angular extrusion

Deformation during conventional (nonisothermal) hot working of metals via equal-channel angular extrusion (ECAE) was investigated using two-dimensional (2-D) and three-dimensional (3-D) finite-element modeling (FEM) analysis. The effects of material flow properties, die-workpiece heat-transfer and friction conditions, and die design on metal flow were examined. Friction and die design were shown to be the most important parameters governing the formation of dead-metal zones during extrusion. On the other hand, thermal gradients induced by die chill and deformation heating were found to exacerbate the extent of flow localization that arises due to material-flow softening alone. The FEM predictions were validated by ECAE experiments on a Ti-6Al-4V alloy with a colony alpha microstructure. Preforms exhibited minor edge cracking and mild flow localization during extrusion at 985 °C, but severe shear localization and fracture during extrusion at 900 °C. The 2-D FEM simulations predicted deformation detail, including shear localization, that was in good agreement with the experimental results, but 3-D FEM simulations were required to realistically predict die chill. A combined approach, in which thermal data were extracted from 3-D simulations and inserted into 2-D simulations, produced load-stroke and fracture predictions in general agreement with measured values.     

Mathematical modeling of the extrusion of 6061/Al2O3/20p composite

An integrated approach, involving laboratory experiments, extrusion plant trials, and finite element modeling (FEM) has been adopted for the study of the extrusion of the metal matrix composite (MMC) 6061/Al₂O₃/20p. Gleeble compression tests were performed to develop the constitutive equation of the MMC under industrial extrusion process conditions. Extrusion plant trials were conducted to measure load and temperature and to obtain samples for microstructural analysis. Metal flow, with respect to particle behavior in the deformation zone, was examined microscopically. An FEM based on the commercial code DEFORM was adopted for the simulation of the extrusion of the MMC; the constitutive equation developed was incorporated into the model. Using an updated Lagrangian formulation, both the transient and steady-state regions of extrusion were modeled. Load and temperature predictions resulting from this model agree well with the measured values in the upsetting stage and in the steady-state region. Temperature predictions agree to within less than 3 pct of the measured values. The FEM predictions of temperature, stress, strain, and strain-rate distribution were correlated with the particle behavior and low-speed cracking during extrusion: large shear deformation promotes particle fracture in the deformation zone, and tensile stress generation in the die land zone of the billet leads to low-speed cracking of the MMC during extrusion. The latter occurs at low temperature in the front end of the billet at the beginning of the extrusion process due to heat loss to the cold die.     

棒材挤压新工艺

采用空心挤压垫即挤压管材用的挤压垫和穿孔针复合使用的新工艺,解决了在只配备锯的管材挤压机上挤压棒材时压余难以分离的问题。     

AZ61镁合金挤压工艺模拟研究

利用有限元软件对AZ61镁合金挤压工艺进行了研究,通过正交试验设计的方法研究了坯料温度、挤压速度、摩擦条件、模具锥角和模具工作带长度对挤压载荷、等效应力及变形均匀性的影响,根据模拟结果提出最佳的工艺参数,为实验的研究提供了参考.     

Densification of porous materials in rigid conical and cylindrical dies

Conclusions A solution obtained by the FEM is proposed to the problem on the nonsteady-state extrusion of a cylindrical porous blank through a conical die and on the extrustion of a porous and a bimetallic blank of varying cross sections through a conical die. Zones of large and small strains are determined from the distribution of porosity. An analysis is made by the FEM of the stressed-strained state in the double-ended densification of porous blanks in rigid cylindrical dies. Cases of the densification of porous bimetallic blanks are also considered.Translated from Poroshkovaya Metallurgiya, No. 5(233), pp. 22–27, May, 1982.