数值模拟技术在火车轮热成形工艺设计中的应用

通过采用体积成形有限元模拟软件DEFORM-3D对火车轮热成形的镦粗、预成形、压弯工艺进行有限元数值模拟与分析,阐述了DEFORM-3D数值模拟技术在火车轮热成形工艺设计中对确定最佳镦粗高度、轮坯轧制变形量、选用合理镦粗模具、预测压弯成形变形最大部位、分析车轮缺陷与坯料缺陷之间的关系等方面的有效应用.这对车轮热成形工艺的合理设计、提升车轮成形质量控制水平、提高生产效率、减低生产成本都具有重要的意义.     

钛合金大型复杂件预制坯成形工艺模拟研究

通过分析TA15钛合金大型复杂件预制坯的外形特点,确定了采用方坯通过自由锻和胎膜锻成形预制坯的工艺方案。基于DEFORM-3D有限元模拟软件,建立了胎膜锻成形的有限元模型,模拟分析了其成形过程,得到了平砧圆角半径、左凸台宽度、胎膜半径对预制坯成形的影响规律,同时通过试验验证了模型的可靠性。结果表明,应先局部镦粗成形凸台,后进行胎膜锻,两工序不能颠倒;平砧圆角半径越大,凸台高度及两凸台间的高度差越大,但右凸台的倾斜程度越来越小;随左凸台宽度的增大,左凸台高度由小于右凸台高度逐渐转变为大于右凸台高度,但对右凸台的高度影响不大;随胎膜半径的增大,左凸台的高度逐渐增大,右凸台的高度逐渐减小,两凸台的高度差逐渐增大。该研究为大型复杂件预制坯成形工艺方案的制定,及胎膜锻参数的选择,提供了理论指导。     

冷锻过程局部镦粗规则的研究及应用

本文以不同高径比的试样在仿真有限元软件DEFORM中进行三维动态模拟,分析不同的模具结构对圆柱体坯料局部镦粗成形过程的影响,研究冷锻过程中的局部镦粗规则,并以伞齿坯的成形为例证明此规则的合理性.     

汽车前指梁多工步成形模拟及试验研究

基于有限元分析软件eta/DYNAFORM,对汽车前指梁的弯曲成形、预成形及内高压成形工艺过程进行了数值模拟。在弯曲成形工步中,研究了管坯各个弯曲位置在相同弯曲半径、不同弯曲角度下的壁厚分布;在预成形工步中主要分析了预制坯形状对前指梁内高压成形的影响;在内高压成形工步中,研究了优化后的预制坯形状对最终成形零件成形缺陷的影响。基于有限元模拟结果,分别进行了弯曲成形、预成形和内高压成形试验。研究结果表明:预制坯形状是决定前指梁内高压能否顺利成形的重要因素;通过改变预成形模具的结构形式,可以得到合理的预制坯形状,避免内高压成形过程中缺陷的产生。实际成形试验结果与数值模拟结果基本一致。     

基于有限元模拟的锥模局部镦粗工艺研究

以数值仿真技术为依托，建立了基于刚粘塑性有限元法的局部镦粗冷成形工艺有限元模拟模型。利用塑性成形仿真软件Deform-3D对锥模局部镦粗工艺进行模拟，分析了该工艺中锥模的角度对杆件局部镦粗成形过程的影响。建立了基于数值模拟结果的锥模角度与坯料高径比的成形规律曲线，为锥模局部镦粗角度的选择提供了理论依据，也为其他局部镦粗工艺参数的选择提供了参考。同时运用本规律曲线指导高径比为6的杆件局部镦粗工艺，得到了良好的结果。     

不同初始条件下粉末锻造镦粗成形致密过程的数值模拟

运用有限元软件MSC.MARC对多孔体粉末烧结材料锻造镦粗成形致密过程进行了数值模拟,研究了不同初始条件(相对密度、高径比、摩擦因子)对粉末锻造成形致密规律及致密机制的影响,并对其结果进行了分析,为预成形坯和模具的优化设计提供理论依据.     

火车车轮镦粗工艺理论分析及数值模拟

火车车轮镦粗工艺对火车车轮成形后续工艺影响很大.在对车轮镦粗工步进行理论分析的基础上采用有限元软件DEFORM对镦粗及预成形工步进行了有限元模拟.研究了镦粗工艺对后续预成形工步的影响,为车轮成形工艺设计提供了理论依据.     

摩托车启动齿预制坯镦挤复合成形工艺研究

通过改变摩托车启动齿预制坯连皮位置,设计了两种镦挤复合成形方案,同时成形凸台和内孔.借助有限元分析软件Deform-3D模拟了摩托车启动齿预制坯的成形过程,分析比较了两种方案中金属流动规律.仿真结果显示,连皮位置设计在圆筒中部时,零件成形质量较高,成形力较小.工艺试验表明,试验结果与数值模拟结果一致.     

铝合金控制臂多向挤压制坯及模锻成形工艺

提出了采用多向挤压工艺为复杂枝权类控制臂锻件成形锻造预制坯。选取典型的复杂铝合金控制臂锻件,通过有限元模拟分析,研究了多向挤压成形过程中毛坯温度、材料流动速度、流线及挤压成形力和模锻成形过程中的温度分布及模具充填情况。模拟结果表明:当坯料成形温度为540℃、模具加热保温至200℃时,挤压后两枝权温度为520℃,枝权头部温度约为480℃,无须进行二次加热。模锻成形材料变形均匀,模具充填效果好,飞边较小,表明挤压制坯与锻造型腔较好匹配。最后,通过多向液压机对模拟进行了验证,结果表明,多向挤压制坯成形工艺可以获得高质量的控制臂锻件预制坯,该工艺具有可行性。     

多孔烧结材料锻造镦粗成形致密的特性研究

粉末锻造是一种新型高性能的精密塑性成形技术，但其成形时的特殊性导致目前缺乏完善的、普遍适应的粉末锻造成形理论。通过对还原铁粉烧结多孔体预成形坯锻造镦粗成形致密实验，研究了不同初始相对密度、不同高径比、不同摩擦条件对预成形坯锻造镦粗成形、致密的影响规律。得到了粉末锻造镦粗的断裂极限准则，绘制出了断裂极限应变迹线，并着重分析了初始相对密度、高径比和摩擦因子对镦粗断裂极限的影响，确定了镦粗成形极限工艺参数曲线。实验研究结果为粉末锻造预成形坯与模具的设计、工艺参数的优化奠定了理论基础，并提供了有价值的实验数据。     

Study of ductile fracture and preform design of upsetting process using adaptive network fuzzy inference system

This paper combines adaptive-network-based inference system (ANFIS) and elasto-plastic finite element to predict the ductile fracture initiation and the preform shape of the upsetting process. From the hybrid-learning algorithm in ANFIS, it can efficiently construct rule database and optimal distribution of membership function to solve the punch stroke which causes the ductile fracture, and the preform shape which results a desired cylindrical workpiece after forming in the upsetting process. As a verification of this system, the punch stroke for ductile fracture initiation and the free boundary radius of the billet after forming are compared between ANFIS and FEM simulated results. In the ductile fracture prediction, it is proved that ANFIS can efficiently predict the ductile fracture initiation successfully for arbitrary friction coefficient and aspect ratio. In the preform shape prediction, the simulated cylindrical radius shows good coincidence with the desired radius after forming. From this forward and inverse investigation, the ANFIS is proved to supply a useful optimal soft computing approach in the forming category.     

Process design of high-strength bolt of fully pearlitic high-carbon steel

In this study, fully pearlitic high-carbon steel, known as a higher delayed fracture strength material, with an ultimate tensile strength of 1410 MPa was used for manufacturing a high-strength M8 bolt. Softening behavior was observed by a compression test of the material. The tensile strength of the material was measured after application of several drawings. On the basis of these test results, two multi-stage manufacturing processes were designed by a knowledge-based expert system in order to develop a high-strength bolt using either the upsetting mode or the extrusion mode for the second preform. The load requirement and possible defect formation during the process were predicted by employing a rigid-viscoplastic finite element analysis. When the second preform was made in a laboratory experiment according to the process design on the basis of the upsetting mode, the specimens cracked at the flange in the final stage of forming. However, the bolt was successfully manufactured using the second preform obtained using the extrusion mode and showed extended tool life in the laboratory test. Finally, the manufactured bolt was confirmed via experiments to have tensile strength of 1600 MPa and delayed fracture strength.     

单工序锻造过程预制坯多目标优化设计的研究

针对单工序锻造在终锻之前一般都需要以镦粗进行预制坯的实际情况，以刚粘塑性有限元为工具，以获得形状和变形均匀性都较好的终锻件为优化设计目标，以镦粗的压下量为优化设计变量，采用黄金分割法对其预制坯工艺进行了多目标优化设计的研究。并对一轴对称锻件的镦粗压下量进行了优化设计，优化取得了明显的效果。     

核电筒体锻件镦粗工艺的云纹法与数值模拟研究

本文用常温云纹法与数值模拟法研究了筒体锻件整体镦粗与局部镦粗工艺的变形规律，得到了整体镦粗工艺的坯料尺寸图。对于在端部内壁处取样的核电筒体锻件，应采用局部镦粗工艺，以锻透取样部位。为避免端部折叠，局部镦粗时单砧压下量应小于１０％。     

火车车轮成形工艺研究及有限元模拟

介绍了火车车轮的成形工艺。采用有限元模拟了车轮成形工艺的镦粗和预成形工步，得出变形过程中材料的流动规律、工件内部的应变场和温度场等信息。通过多次模拟镦粗压下量对预成形的影响，确定了最佳的镦粗压下量。这些信息为变形过程的控制提供了理论依据。     

Analysis of parameters and microcomputer control for the electric upsetting process for forging engine valves

Using both theoretical analysis and practical experiment, it is clearly indicated that the electric upsetting process should be divided into two stages: preform upsetting and finish upsetting. The main process parameters influencing the forming quality of engine valves, balancing and matching of these parameters, and the microcomputer system used to control them are described. By using the microcomputer system to control the whole process automatically, the rate of efficient production could be considerably increased.     

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.     

DETERMINATION OF THRESHOLD PRESSURE FOR INFILTRATION OF LIQUID ALUMINIUM INTO SHORT ALUMINA FIBER PREFORM

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The application of neural networks in the preform design of the upsetting process

Design of the optimum preform for near net shape manufacturing is a crucial step in upsetting process design. In this study, artificial neural networks (ANN) are used to consider different interfacial friction conditions between the top and bottom die and billet interface. Two back propagation neural networks are trained based on finite element analysis results considering ten interfacial friction conditions and varying geometrical and processing parameters, to predict the optimum preform for high strength (HS) steel and commercial aluminum. Neural network predictions were verified for three new problems of both HS steel and commercial aluminum and observed that these are in close match with their simulation counterparts. It was further Experimentally verified with two commercial aluminum specimens and observed that the preform values predicted by ANN are in good agreement with experimental results.     

The Effect of Geometric Parameters of Conical Cups on the Preform Shape in Two-Stage Superplastic Forming Process

A combination of sensitivity analysis and finite element simulation has been developed for the preform design in two-stage superplastic forming process. The aim is to present a simple approach to generate an estimate for the preform shape. In this respect, the commercial finite element software ABAQUS/Standard 6.8 was used as a computational tool and sensitivity analysis was used for preform design by minimizing the mean fractional deviation from the target thickness as an objective function. The predicted preform was verified through comparison with experimental results by investigating the deformation of AA5083 sheet at temperature of 500 °C. The effect of the geometric parameters of conical cups on the preform shape was examined. The results showed that the geometric parameters have a significant effect on the preform shape. By increasing the height and the cone angle of the final cup, the depth of the preform in the inner cavity decreases and the dome region is approached to the center of the preform cup. By increasing the corner radius of the final-die, only the height of the dome region decreases.