FINITE ELEMENT MODEL AND SIMULATION OF ROTARY FORGING OF A DISC

The rotary forging process of a disc is simulated by 3-D finite element method.The motion of the rotary the is described as the combination of a revolution round the machine axis and a spin round the rotary die axis. Therefore, the workpiece can be loaded and unloaded partly and cyclically by the cone surface of the rotary the continuously, according with the practical rotary forging process. From the siumulation rasults, the causes of center-thinning during rotary forging of discs are that the locally loading of rotary die made the workpiece center get high radial and tangential tensile stresses, and then the shortening in axial direction and the elongating in tangential and radial direction occur continuous- ly.

Modelling and simulation of contact force in cold rotary forging

Cold rotary forging is an advanced and complex metal forming technology with continuous local plastic deformation.Investigating the contact force between the dies and the workpiece has a great significance to improve the life of the dies in cold rotary forging.The purpose of this work is to reveal the contact force responses in cold rotary forging through the modelling and simulation.For this purpose,a 3D elastic-plastic dynamic explicit FE model of cold rotary forging is developed using the FE code ABAQUS/Explicit.Through the modelling and simulation,the distribution and evolution of the contact force in cold rotary forging is investigated in detail.The experiment has been conducted and the validity of the 3D FE model of cold rotary forging has been verified.The results show that: 1) The contact force distribution is complex and exhibits an obvious non-uniform characteristic in the radial and circumferential directions; 2) The maximum contact force between the upper die and the workpiece is much larger than that between the lower die and the workpiece; 3) The contact force evolution history is periodic and every period experiences three different stages; 4) The total normal contact force is much larger than the total shear contact force at any given time.

STUDY ON THE NUMERICAL SIMULATION OF MULTI-STAGE ROTARY FORGING OF A NON-AXISYMMETRIC PART AND THE CAE ANALYSIS OF THE DIE STRENGTH

Traditionally a rotary forging process is a kind of metal forming method where a conic upper die, whose axis is deviated an angle from the axis of machine, forges a billet continuously and partially to finish the whole deformation. For the rotary forging process simulation, more researches were focused on simulating the simple stage forming process with axisymmetric part geometry. Whereas in this paper, the upper die is not cone-shaped, and the billet is non-axisymmetric. So the movement of the punch is much more complicated than ever. The 3D FEM simulation models for the preforming ＆ final forming processes are set up aider carefully studying the complicated movement pattern. Deform-3D is used to simulate the material flow, and the boundary nodal resisting forces calculated by the final stage process simulation is used to analyze the final forming die strength. The CAE analysis of the die shows that the design of the final forming die is not reasonable with lower pre-stress which is easy to crack at the critical corners. An optimum die design is also provided with higher pre-stress, and verified by CAE analysis.

Densification laws and properties of sintered powder compacts in rotary forging process

In order to obtain high property powder metallurgy products, at present rotary forging process has often been used to further densify the sintered powder compact, but the densification law and property analysis have very rarely been studied, therefore the densification laws of sintered powder compacts being composed of Fe 0.8%C 4.0%Cu 0.2% zinc stearate and formed as cylindrical shape by double action pressing, and then further densified as well in a rotary forging process was studied by orthogonal experiment and regression analysis. The experimental results show that the H / D ratio and the rotary forging force are major factors affecting the density of the sintered powder compacts in the rotary forging process. The effect of the H / D ratio and the rotary forging force on the density were discovered. By determining both the density and the hardness of compacts, it was found that the density distributions show no difference from the hardness distributions and that the gradients of the density and the hardness in the axial direction are larger than those in the radial direction.

Prevention of thinning at disc center during rotary forging

Presents the simulation and analysis of the rotary forging of a disc using a finite element method, which reveals the thinning at the disc center is caused by higher radial and tangential tensile stresses resulting from the local loading of a rotary die and acting at the center of a workpiece, and proposes a new design of rotary die with a hole opened in its center to prevent the continuous occurrence of shortening in the axial direction and elongation in the tangential and radial directions, and concludes from simulation results that the rotary die with a hole opened in its center is effective for prevention of thinning or cracking at the center of a disc during rotary forging.

旋转锻造加工高比重W-Ni-Fe合金的退火工艺研究

使用粉末冶金工艺制备Ni/Fe为7∶3的W-Ni-Fe高比重钨合金,在使用旋转锻造方法进行形变强化后进行热处理。结果表明,锻造态W-Ni-Fe合金经过一定温度的锻后退火,强度有所提高,而塑性下降。样品的强度在一定的退火温度和保温时间范围内能得到提升,更高温度和更高时间的保温会使样品强度下降。不同钨含量的W-Ni-Fe合金,强度提升最大的退火温度和时间条件不同。SEM图像显示,退火前样品钨颗粒因旋转锻造变形呈现长条状织构,退火后钨颗粒的形状无明显变化。这些现象说明,锻造变形的合金样品经过锻后退火发生应变时效现象,使强度得到提升。研究明确了不同钨含量的W-Ni-Fe合金最佳的锻后退火工艺参数。

摆辗机分类及我国摆辗技术发展分析

将摆辗机按摆角是否可调进行分类,并展开分析,指出我国摆动辗压发展的主要技术瓶颈是摆角可调的双偏心套传动机构摆动辗压机没有实现国产化。所以具体从摆动辗压技术的优缺点,摆动辗压机的结构特征、主要技术参数、摆辗力-滑块位移规律以及摆辗工艺参数全方位展开论述,指出摆动辗压理论研究须与生产实际相结合,才能解决生产实际中的问题;锻压设备制造商应积极参与研发摆角可调的双偏心套传动机构摆动辗压机。

立式摆辗机及其摆辗装置的优化设计

摆辗机是回转锻造的重要装备,其主要有摆辗机主体及摆辗台组成,主要分为卧式、立式两种结构,本文所述的立式摆辗机其主传动结构区别于传统的下传动方式,由上传动液压缸驱动运动滑块下安装的摆辗台,通过摆辗台的下压运动,对工件进行垂直压力;对摆辗台内部传动结构进行优化设计,防止摆辗台的偏心轴在进行圆锥运动时产生自转,避免摆辗头因摩擦降低使用寿命且损伤工件的情况发生。

基于Forge的汽车空心EPS转向轴旋锻成形数值模拟及工艺优化

利用Forge软件对08钢汽车空心EPS转向轴旋锻成形进行了数值模拟,通过正文试验研究了锤头相对转角、下压量、进锤速度和坯料轴向进给量对关键部位成形过程的影响。获得了汽车空心EPS转向轴旋锻成形的较优工艺参数:锤头相对转角为18°,压下量为1 mm,进锤速度为5 mm/s,坯料轴向进给量为0.5 mm。最后以优化的参数进行了样品试制,结果表明该组工艺参数所生产出的样品性能优良。

Research on rotary forming mechanism of cartridge bottom by FEM

The rotary forging of a cartridge bottom is simulated by finite element method with DEFORM TM . The analysis of stress and strain rate results indicates that the deformation conditions and the final geometry of a product are not completely axis symmetrical under the partial loading conditions during the rotary forging operations. It is therefore required to have a few more rotary forging cycles at the end of total feeding to eliminate nonuniformity. The results of simulation show that the optimization of rotary forging process conditions can be achieved to avoid the underfill defect resulting from improper process conditions. This technology can be used to manufacture ring components with thin bottoms by properly controlling the working process and the tooling motion.

Plastic forming behavior of axisymmetric bimetal products with rotary swaging

In this paper,an elasto-viscoplastic three-dimension(3D) finite element model is developed to simulate the processing of bimetal tube with rotary swaging. Through simulation,the effects of high-frequency pulse stroking on the distribution and histories of stress,stain and loading are clarified. The stress in inner tube is compressive and higher than the minimum bonding force. Meanwhile,the stiffness of inner tube impacts outer tube extension in length.

含芯棒旋锻芯轴尺寸对坯管几何变形的影响

以某液压缸筒的含芯棒旋锻为实例,研究含芯棒旋锻过程中芯轴尺寸对坯管几何变形的影响。在相同的进给参数下,芯轴尺寸变化会改变模具和芯轴同时参与锻打的总锻打次数。通过软件仿真不同芯轴尺寸下含芯棒旋锻锻打全过程,得到锻件的变形数据,分析芯轴尺寸对坯管变形的影响。结果表明,芯轴尺寸变化会改变锻件内外表面的直线度和圆柱度,但不影响锻件的圆度,且当芯轴尺寸增加到一定值时,锻件的内外表面直线度和圆柱度几乎不发生变化。

高筋薄板构件多自由度摆动辗压成形规律与工艺研究

高筋薄板构件多自由度摆动辗压成形过程中金属流动十分复杂,导致高筋薄板构件筋高分布十分不均匀。根据双偏心套型摆动辗压机运动原理,探究摆动模做圆轨迹和螺旋线轨迹运动时摆动模与坯料的接触模式演化规律,提出了接触区形状数学计算方法。采用有限元模拟仿真技术揭示摆动模做圆轨迹和螺旋线轨迹运动时高筋薄板构件摆动辗压成形金属流动规律以及高筋生长规律,阐明摆动模运动、接触区变化、金属流动和高筋生长之间的关联关系。在此基础上,开展高筋薄板构件摆动辗压成形工艺试验,实现高筋薄板构件摆动辗压成形。研究结果表明,相比圆轨迹运动,摆动模做螺旋线轨迹运动能够减弱金属径向和切向流动,增强金属轴向流动能力,从而有效提高高筋薄板构件摆动碾压成形过程中金属轴向流动的均匀性,获得筋高分布均匀的高筋薄板构件。

某液压缸筒含芯棒旋锻轴向残余应力研究

以某含芯棒旋锻液压缸筒为研究对象,对不同尺寸下旋锻过程中的轴向残余应力分布进行仿真,绘制产品沿径向方向的轴向残余应力,分析不同尺寸毛坯对轴向残余应力影响。研究发现,随着毛坯外径和毛坯厚度增加,其轴向残余应力无论是压应力还是拉应力都呈递增趋势,但并未对任一类尺寸表现出更敏感的变化趋势。进一步通过相同截面积毛坯仿真发现,轴向残余应力具有高度相似性,证明毛坯截面积为影响轴向残余应力分布的关键因素。

铝合金车轮回转碾锻研究

随着汽车工业的迅速发展,对车轮的品质要求也在逐渐提高。车轮作为汽车、摩托车的传动部件,不仅是安全件,还是外观件。为此,本文重点介绍了铝合金车轮的锻造加工成型方式,探讨了回转碾锻这种先进的锻造技术,以更好的提升车轮产品的成形质量与效率。

Simulation and Analysis of Microstructure Evolution of IN718 in Rotary Forgings by FEM

A numerical analysis was performed to study the in?uence of process parameters on the microstruc-ture evolution of IN718 alloy in rotary forging using the finite element method(FEM).For this purpose, a constitutive equation considering the effects of strain hardening and dynamic softening of IN718 alloy was built.The constitutive equation and microstructure models were implemented into the finite element code to investigate the microstructure evolution during rotary forging subject to large deformations.The simulations were carried out in the ratio of initial height to diameter range 0.2-0.8, the angle of the rocker 3°-7° and the relative feed per revolution range 0.01-0.1 r-1.The research results revealed the deformation mechanism and the correlation of process parameters with the grain size evolution of IN718 alloy during rotary forging.These provide evidence for the selection of rotary forging parameters.

螺旋伞齿轮摆动辗压试验

根据汽车后桥从动螺旋伞齿轮的锻件图设计并制造了预制坯和辗压试验模具;铅试件辗压试验结果证明辗压成形工艺和模具设计的可行性;成形试验和网格试验分别显示了齿形的充填过程和内部金属网格的变化趋势,揭示出从动螺旋伞齿轮辗压成形金属流动规律和应变分布状态;测试了螺旋伞齿轮辗压力压下量曲线,提出了消除齿端充填不足的主要措施。

扭转振动摆动辗压精密成形机理研究

介绍了扭转振动摆动辗压的工作原理和实施方法,分析了扭转振动在摆动辗压塑性成形过程中的作用机理,在对模具———工件系统进行运动分析的基础上,确定了摆辗角速度与振动频率之间的关系,建立了扭转振动摆动辗压应满足的速度条件,计算了单周期内扭转振动摆辗的成形时间、沿圆周方向的成形角位移和成形长度等工艺参数;通过本文的理论推导表明,扭转振动摆动辗压的效率与振动频率和进给速度成正比,扭转振动摆动辗压成形的成形效率比纵向振动摆动辗压成形的成形效率高。

精密旋锻技术的研究进展

近年来精密旋锻技术在汽车轻量化方面发挥越来越重要的作用,尤其是空心轴类零件在汽车上的应用。本文从旋锻技术的原理和特点出发,综述了国内外精密旋锻技术的研究进展。重点介绍了旋锻汽车空心半轴的力学性能,简要介绍了旋锻连接技术的应用。

销类件摆辗精密成形及三维有限元模拟

介绍销类件冷拔摆辗精密成形工艺，对工艺参数的确定、产品质量和变形机理的有限元模拟等问题进行了研究。实验表明采用摆辗工艺生产销类件，金属流线不被破坏，表面硬度略有升高，尺寸精度和表面粗糙度达到有关标准要求，综合机械性能有所提高，是一种先进的销类件精密成形工艺。采用三维有限元模拟摆辗变形过程，可以获得接触区和工件内部应力应变场等信息，为控制变形过程，保证产品质量提供理论依据。