高速列车制动盘盘毂锻造工艺数值模拟

基于实测的40CrA钢高温应力-应变曲线和热物性参数,建立了高速列车制动盘盘毂毛坯在模锻过程的有限元模型。运用DEFORM-3D软件,对该盘毂的多步骤锻造过程进行热力耦合模拟,得到了应力、应变和温度随时间的变化规律;研究盘毂成形过程的金属流动机制,模拟了产生折叠缺陷的位置;预测了盘毂完全成形所需的锻锤打击次数;对终锻模具的最大主应力进行分析,预测了模具在实际生产中可能产生的塌陷、开裂缺陷及其位置。根据模拟结果进行了生产试制,验证了工艺的可行性和模拟的准确性。     

汽车盘毂精密锻造工艺仿真研究

汽车盘毂是汽车离合器总成的重要组成零件,要求具有高强、高韧、耐冲击、抗疲劳等综合力学性能。传统的生产工艺由自由锻制坯和机械加工生产,产品力学性能及材料利用率较低,且生产中煤炭炉加热能耗巨大,污染严重。本公司与太原科技大学机械工程学院进行产学研合作,提出汽车盘毂零件的精密闭式模锻成形工艺,并对成形工艺进行计算机仿真计算,通过理论分析和模拟,提出合理的锻造工艺;分析了零件精密闭式模锻变形过程的载荷变化规律、温度变化规律和摩擦系数对零件成形的影响,进一步修正了零件精密闭式模锻工艺。     

锻造工艺对TC11饼材显微组织和性能的影响

采用3 t锤及1250 t压力机两种不同设备及自由锻工艺制取了TC11钛合金饼材,并分别测试了其室温和高温力学性能及超声波杂波水平。研究结果表明:两种锻造工艺所制得的TC11钛合金饼材性能均符合要求,组织均为等轴α+片状α的双态组织或长条α+片状α组织,但后者晶粒较细且组织均匀性较好;在1250 t压力机上生产的TC11钛合金饼材室温和高温抗拉强度分别比3 t锤上生产的分别高出50和20 MPa左右,屈服强度高20 MPa左右,而伸长率、断面收缩率基本持平;在1250 t压力机上生产的TC11钛合金饼材比3 t锤上生产的饼材超声波杂波水平低3 d B。因此在1250 t压力机上生产的饼材性能比在3 t锤上生产的饼材性能更加优越。     

Investigation of dynamic effects during cold upset-forging of sintered aluminium truncated conical preforms

The present paper deals with the upper bound analysis, experimental investigation and computer simulation of upset-forging of sintered aluminium truncated conical preforms, which considers heterogeneous deformation due to barreling of preform slant sides, composite die-workpiece interfacial friction conditions, preform densification along with compression and inertia effects. A generalized theoretical expression for average forging load and preform bulged profile based on the exponential velocity field and strain rate has been established. The upset-forging experiments were conducted using the sintered preforms prepared by compacting aluminium metal powder in the closed dies and various deformation characteristics were measured. Finally, the computer simulation of the upset-forging of the sintered aluminium truncated conical preforms was performed using DEFORM software and the deformation behavior velocity, effective strain and effective stress distribution were critically studied. The effect of die speed, i.e. dynamic effects on average die load has been investigated using energy and load factors. The DOE (Design of Experiment) and RSM (Response Surface Methodology) techniques were also used to investigate and determine interrelationships between important upset-forging characteristics and the results were presented graphically. During the present investigations, it was found that inertia energy dissipation and energy factor increases, where as die load and load factor decreases exponentially with die speed. It is expected that the present work will be useful for effective assessment of various deformation characteristics during processing of sintered materials, especially at high-speed.     

离心风机叶轮盖盘热锻有限元分析

采用热锻工艺方法对离心风机中叶轮盖盘进行成形研究。首先对盖盘常用材料FV520B进行了热模拟性能测试,建立了该材料的本构方程,利用该本构方程在Deform-3D平台下对盖盘热锻成形过程进行了有限元模拟研究,获得了盖盘热锻成形过程中成形力的变化,以及成形工件的应力、应变、温度和损伤分布,为盖盘热锻成形新工艺的实验研究提供了理论依据。     

汽车贯通轴平锻工艺

汽车贯通轴锻件,总长约867 mm,锻件中间局部尺寸粗大.原采用热模锻工艺生产,材料利用率较低,现改进为平锻工艺生产,每根锻件节材3.6 kg.在开发平锻工艺的过程中,发现锻件端头Φ42 mm处很难充满,而中间Φ76 mm的部分因加热质量等因素的影响,质量很不稳定.调试后,对锻件图和平锻工艺又进行了改进,并最终取得了成功.该工艺对类似的长轴类锻件采用平锻机生产,有一定的借鉴作用.     

Modelling of metal flow during hot forging with regard to microstructural aspects

A mathematical model has been proposed for evaluation of velocity and temperature fields in hot forging operations for axisymmetric parts. The model can be applied to determine forging load, strain rate, strain and temperature distributions. In addition, the effects of temperature and strain rate on metal flow have been considered through simultaneous modelling of dynamic phase transformation within the deforming metal. Hot forging experiments have been carried out under different working conditions and the results have been compared with the predictions. A good agreement between the simulated and experimental results was found.     

GH864合金涡轮盘锻造过程中微观组织的数值模拟

为了预测GH864合金φ1250 mm涡轮盘锻造过程中微观组织的演变规律,将微观组织模型加入到模拟软件MSC Super-form中,实现了高温合金塑性变形-传热-微观组织演变的耦合.研究了不同变形工艺参数对涡轮盘组织分布的影响,包括初始变形温度、变形速率、模具预热温度、摩擦系数及保温措施等的影响.结果表明:实际φ12...     

转轮叶片热模压成形压力中心的动态计算

为确保实际生产中压力中心的波动始终处于设定的公差范围之内,提出一种基于刚塑性有限单元法,通过实时节点力的计算来获取非均匀厚度板料成形压力中心的动态算法.推导了相应的计算列式,采用DEFORM软件二次开发实现了该算法.同时,建立了水轮机转轮叶片热模压成形过程的有限元模型,结合上述算法给出了具体的压力中心坐标值,为压力中心的优化提供了必要的数值基础.     

大锻件锻造过程中温度场测定及其结果分析

大型锻件锻造过程中工件温度场的变化规律对于保证锻件质量具有重要作用,由于锻件受环境温度、保温情况等诸多因素影响,生产中很难准确预测锻件锻造过程中温度变化规律。通过实验模拟实际生产中锻件加热曲线,在不同保温措施下,取锻件芯部至表层不同测控点进行锻造过程中的温度测量,通过数据分析建立了Mn18Cr18N护环钢锻造过程中的温度场,得出锻件的温度差与时间变化曲线及温度变化速率图,描述了工件在一定保温措施下的温度场变化情况,其结论对准确了解Mn18Cr18N护环钢锻造过程中的温度变化规律具有实际指导意义。     

锻造操作机钳杆机构的动态分析

采用SolidWorks和ADAMS软件建立了锻造操作机的虚拟样机模型,用虚拟样机技术对钳杆机构进行了仿真分析,精确得出操作机设计所需的重要参数,计算了夹紧力的大小和驱动力矩的变化规律,合理地减小了夹紧缸的直径,为操作机的其他部分提供了更多的设计空间。在仿真结果的基础上,采用ANSYS软件对钳臂进行了优化设计,降低了节点的最大应力值。     

搅拌摩擦焊中锻压效应的强化与作用

为直观证明倾斜工具能强化搅拌搭接摩擦焊中的锻压效应之事实,提出了一种新的实验方案(采用预先开有小孔的垫板)并获得了预期效果.采用无针柱状搅拌头与预先开有φ4mm小孔的垫板,分别在有/无倾角的两种情况下进行了2 mm厚薄铝板的搭接搅拌摩擦焊.结果表明,在倾角为3°情况下被挤入垫板小孔内的塑化金属的长度(5.3 mm)远大...     

重型锻压机刚柔耦合系统动力学分析

为对锻压装备优化设计、制造、故障诊断提供理论依据,采用刚柔耦合动力学模型,以315t液压机实验平台为研究对象,研究其动力学性能。基于有限元模态分析,得出了预应力结构的工程意义。应用动力学分析软件ADAMS,提出了创建液压机刚柔耦合模型的研究方法,揭示了系统动力学特性与时变负载的关系。数值仿真结果表明:预应力结构能够有效地增加系统刚度,减小结构弹性变形;同时,平衡系统能够显著地降低偏载的不利影响。     

The effect of nitrogen on the cold forging properties of 1020 steel

We have studied the effect of nitrogen on the cold forging properties of a low carbon steel as a function of temperature. Five AISI 1020 steels with nitrogen contents from 12 to 180 ppm were examined by tensile testing from 25 to 371 °C. Yield strength, tensile elongation (ductility), ultimate tensile strength (UTS), strain hardening exponents and strength coefficients were determined. The influence of nitrogen on the mechanical property behavior of this low carbon steel exhibits trends as expected—when nitrogen content increases, the strength of the steel increases and the ductility decreases. Likewise, as the temperature increases, the strength of the steel generally decreases; however, the ductility initially decreases, then exhibits an increasing trend. Additionally, there is an intermediate temperature range for these alloys where anomalous behavior is observed. Serrated stress–strain curves seen in this temperature range are indicative of dynamic strain aging. It is probable that this anomalous mechanical property trend is due to dynamic strain aging.     

基于楔横轧预制坯的中空气门终锻凸模设计

对中空气门楔横轧-模锻成形工艺终锻成形过程中的凸模形状尺寸进行研究。根据预成形毛坯终锻过程的成形特点,设计3种不同初始尺寸的终锻成形凸模,采用实验与模拟相结合的方法研究其对预成形毛坯终锻成形过程的影响。模拟结果表明,终锻成形过程中凸模芯轴太短,将出现凸模芯轴前端聚料的现象,导致无法成形出终锻件的盘部型腔尺寸;而实验结果表明,凸模芯轴太长会在实际生产中导致成形后终锻件难以脱模。通过综合模拟与实验结果的分析,获得了凸模芯轴的设计原则,确定了合适的凸模芯轴长度,并且依据该凸模设计原则,进行终锻成形,获得了形状尺寸合理的终锻件。     

Prediction of recrystallization behaviors in a steel billet during hot forging

Multi-recrystallizations occurring in a steel billet during hot forging were predicted. The prediction was obtained by coupling rigid thermoviscoplastic finite element analysis and recrystallization modeling equations. The finite element analysis was preformed for nonisothermal deformation as well as heat transfer for the entire forging process. As a result, it was predicted that three or four times of recrystallizations occurred in the billet and that resulting grains varied in size for different locations. The final grain sizes at the locations in the billet were measured and compared with predicted ones. It was found that they were in good agreement.     

一级涡轮盘锻造开裂原因分析

根据GH4 133B高温材料试验结果 ,应用数值模拟技术对高温合金一级涡轮盘锤锻工艺进行了数值模拟 ,模拟结果揭示出 :初锻温度较低、锤的间隔时间和运料时间较长可能是引起开裂的重要原因。根据对开裂原因的分析 ,提出了避免开裂的工艺方案。后续的数值模拟工作和锻造实验证明 ,应用改进的方案可以制造出合格的高温合金涡轮盘锻件     

基于ANN的涡轮盘等温成形过程模拟电路模型

为提高锻件质量和成品率,有必要建立一种适合于实时控制的锻件成形过程模型.利用有限元模拟技术对涡轮盘的等温成形过程进行了虚拟正交试验,通过对成形过程的载荷--行程曲线的分析,建立了粉末高温合金涡轮盘件等温成形过程的人工神经网络(ANN)模型,并将其映射成模拟电路模型.以此模拟电路模型为参考模型,应用于模型参考自适应控制(MRAC)系统,对涡轮盘件等温成形过程进行控制.结果表明,所建立的ANN模型及其模拟电路模型对粉末高温合金涡轮盘件等温成形过程的拟合精度很高,且控制参数始终与模型输出相吻合,为实现盘件成形过程的实时控制奠定了基础.     

轻合金汽车轮毂的生产方法

以铝合金和镁合金为例,简要介绍目前生产轻质合金轮毂的主要方法,仍以传统的铸造法为主,锻压法为辅,并在此基础上开发出了各种新的成形技术。评述了各种生产方法的优缺点。     

Fracture behaviors of AZ80 magnesium alloy during multiple forging processes

1 Introduction Pure magnesium and magnesium alloys are the lowest density metals used as structural materials and have excellent specific strength and stiffness, machinability, dimensional stability, and excellent recycling capability. They are, therefor…