Two step forging process of spur gear based on rigid parallel motion

To improve the forging process of spur gear,the metal flow rule is investigated in detail,and a hypothesis of radial rigid-parallel-motive (RPM) flow mode is given. Based on the RPM mode a novel specific gear forging technology is put forward by introduced upend forging process and constrained divided-flow technique. Firstly,finite element method is used to simulate the upend forging pre-forming and RPM finish forging,and equivalent stress field and load-stroke curve are investigated. Secondly,a correspondi...     

Microstructure Evolution of Different Forging Processes for 12％Cr Steel During Hot Deformation

Five forging experiments were designed and conducted to investigate the effect of process parameters on microstructure evolution during hot deformation for X12CrMoWVNbN10-1-1 steel.The experimental results indicated that average grain size became finer with the increasing number of upsetting and stretching.Especially,the size of stretching three times with upsetting twice had the most remarkable effect on refinement,and the size was only 27.36%of the original one.Moreover,the stress model was integrated into the software and finite element models were established.Simulation results demonstrated that the strain at center point of workpiece was far larger than critical strain value in each process,so that dynamic recrystallization(DRX) occurred in each workpiece,which implied DRX could occur for several times with the increasing number of upsetting and stretching,and uniform finer microstructure would be obtained.However,the results also showed that higher temperature was an unfavorable factor for grain refinement,so the times of heating should be limited for workpiece,and as many forging processes as possible should be finished in once heating.     

Simulation of large forging flat-anvil stretching process and its optimization

In this paper, a kind of mathematic method for optimizing stretching process of large forgings is proposed. Distributions of effective strain within forged ingots is described by a Gauss function, which is obtained from the simulation of flat-anvil stretching process. Successive stretching is expressed by the superimposing Gauss functions. Optimized stretching process, with both homogeneous and certain strain in the center of forgings, is presented by derivation of this function. The relationship between effective strain and the values of feed is obtained during the successive stretching with a rotation angle of 90° and a feed displacement of 1/2 anvil width. The optimization result is verified by finite element simulation. Optimized value of feed obtained using this method can ensure both uniformity and forging penetration. It provides mathematic model and theoretic basis of optimizing large forging stretching process.     

Coupled Thermo-Mechanical Modeling of Long Cone-Shaped Forging Based on Rigid Visco-Plastic FEM

Based on synthetically considering the coupled thermo-mechanical relations between temperature and deforming,a numerical simulation of the forging process for the special long cone-shaped workpiece of Al-5.44M-2.15L-0.12Zr alloy at high temperature was conducted by using the rigid visco-plastic finite element method.The relations between the total load and the displacement druing the forging ,and the distributions of stress,strain,temperature and strain rate,which can provide useful information for the process design,are obtained.     

辊锻模具设计的理论及试验研究

通过对辊锻模具与锻件的啮合运动分析，推导出由锻件轮廓方程确定模具型槽方程的理论公式，并通过试验对该公式进行了验证。     

Numerical analysis of unconventional forging process of hollowed shaft from Ti-6Al-4V alloy

This paper presents theoretical analysis of unconventional forging process of hollowed shaft from Ti-6Al-4V alloy in a three-slide forging press. This method in comparison with other metal forming methods allows for obtaining of hollowed products. The designed process is verified theoretically by means of numerical simulations based on finite element method with assumption of 3D state of strain. The following factors are considered in the analysis: material flow kinematics, strain distribution, temperature distribution and force of process. On the basis of results, it is stated that the application of designed technology allows for obtaining of a product of assumed quality. A comparison is made between material consumption in analyzed process and material consumption in typical metal forming methods, also in used at present technology of shaft manufacturing by machining only. It is stated that the application of forging in the three-slide forging press allows for a considerable decrease of manufacturing costs due to material savings and decrease of labor consumption of operations at finishing.     

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.     

Computer Simulation of Thermal-Mechanical Processing

AlterationIntroductionThereisastrongini6ractionamongtemPetalrefield,strCssfield,andmicrosttuctutulaltOrationinm8terialsduringtheirhotworking[l'2].Especiallyduringthecoolingprocess,inwhichtemPeratorechangnsgreatly,intendionsbecomemorecomplexbecauseoftransformationoccurmnce.Duringthehotdeformation,thingswillaPpearsuchas:a.hotdeformation,relatedtostressfieId,changesessentiallytheshaPeofmaterialsandcausesthevariationofthecontactstatebetWeenthedieandsample,resultinginchangeofthethermalboundnyco…     

Investigation on Zener-Hollomon Parameter in the Warm-Hot Deformation Behavior of CF53

The warm-hot deformation behavior of CF53 steel was studied with hot compression tests at temperature of 1 123 ~1 273 K and strain rate of 0.1~20 s -1 . The activation energy for warm-hot deformation is 274.816 kJ/mol. The influences of Zener-Hollomon parameter, strain and grain size imposing on the flow stress were analyzed in the temperature range of warm-hot forging. Based on the creep theory and mathematic theory of statistics, mathematical models of flow stress were obtained. The results provide a scientific basis for controlling microstructure of forging process through Zener-Hollomon parameter.     

突缘叉模锻件折叠缺陷分析

通过对缺陷的内部结构进行分析,发现突缘叉锻件法兰底面产生缺陷的主要原因是模锻前制坯工艺不合理,造成模锻时金属回流,产生折叠.提出改进制坯工艺消除锻件的缺陷的方案,经工艺和生产验证,消除了锻件缺陷,提高了锻件质量,取得满意效果,该工艺的成功应用,可为同类型产品的生产提供借鉴.     

5CrNiMo钢锻模液态模锻工艺试验

采用液态模银代替自由锻造生产转向螺母5CrNiMo锻模，给出了其下模结构设计参数，介绍了5CrNiMo合金液态模锻工艺参数取位范围，分析了制件的质量。     

Computer Aided Simulation on Precision Cold Forging of Universal Joint Cross

IntroductionThefiwtee1emenmethod(FEM)playsanextrmelyimPortantroleintheanalysesofengineeringproblems.ForalongtimethismethodhasmainlybeenaPPliedinthelinearfieldandshownitsgreatpower.HoweveealOtofnonlinearengineeringPrOblemsWhichcanneitherbesimPlyreducedtolinearonesnorrCPresentedbylinearlyanalogywhichshallchnsethePfacticalconditionsrelativelymuch,havechallengedfiniteelementmethod(FEM).RecentymuchProgresshasbeenmadebothinthemathematicalandmechanicaltheoryandthecomPulertechnologysothatevent…     

消失模液锻中气隙压力和气流速度的计算分析

通过计算分析了消失模液锻制备颗粒增强金属基复合材料中，附带的增强颗粒泡沫载体与金属液作用后产生的气隙压力和气流速度，然后在消失模液锻TiC／ZG270-500实验中测量气隙压力和气流速度值，并探讨液锻工艺参数对气隙压力和气流速度的影响规律．实验结果表明：气隙压力和气流速度随充型速度、浇注温度、内浇口与排气孔横截面积比呈递增趋势，但均不随成形压力变化．此外，气流速度还随排气孔与型腔横截面积比增大而增大，气流速度随工艺参数变化趋势较平缓．     

Finite Element Analysis for Multi-pass Equal Channel Angular Pressing

Equal channel angular pressing (ECAP) is an attractive process method to produce bulk ultra-fine grained materials. There are many experiment evidences showing that the nature of the microstructural evolution in multi-pass ECAP depends on process routes. Isothermal three dimensional FEM simulations for multi-pass ECAP were performed using DEFORM3D finite element code. The material model of 6061Al-T6 was employed. Flow nets, effective strain distribution in the workpiece and loads during multi-pass ECAP using different routes were analysed respectively. The simulations show process routes influence material flow and effective strain distribution in the workpiece obviously but have few influence on loads.     

辊锻模型槽与锻件轮廓曲面的几何分析

通过对辊锻模与锻件的啮合运行分析,发现了锻件轮廓也型槽轮廓存在着共轭关系,导出了共轭曲面参数方程,此结果对于精确,高效设计辊锻模具具有重要意义 。     

纯铝的多轴非比例循环塑性行为实验研究

为纯铝材料进行了４种应变路径和２种轴向应力－扭转剪应变组合路径的非比例循环试验,揭示了纯铝在非比例循环加载下塑性应变率方向和塑性模量的演化特征;分析了纯铝的多轴棘轮行为。得到了一些有意义的结果。     

Ⅰ型裂纹稳定扩展裂尖塑性区研究

运用FRANC2D/L软件分别对6.35 mm和2 mm两种厚度Arcan试件的Ⅰ型裂纹稳定扩展进行数值计算,研究了该软件的网格划分技术对计算结果的影响,发现该软件的计算精度主要受裂纹区的网格密度影响（当裂纹面单元与裂纹每步扩展单元尺寸一致时,计算精度好）.通过分析有效应力,研究了材料、裂纹扩展长度及试件厚度对裂纹尖端塑性区尺寸的影响.研究结果表明,材料的屈服应力越大,其裂尖塑性区尺寸越小;塑性区尺寸随裂纹扩展长度的增加,先增大后趋于不变;塑性区的形状与板厚或边界有关,6.35 mm厚的母材及3种焊接板材塑性区成扩散型,2 mm厚的母材成Dugdale模型,25.4 mm以上厚度母材成平面应变模型;裂纹启裂时,塑性区随着厚度的增加而减小,最终不变.     

A method to analyze the voltage-actuation response of a pre-strained circular dielectric elastomer actuator model

Dielectric elastomers (DEs) are the polymers capable of inducing deformation under electrical stimulation. When subject to a voltage across its thickness, the material reduces in thickness and expands in area. This paper presents a new method to analyze deformation and stress distribution response of the dielectric elastomer actuator (DEA) model under different applied voltage. An equal-biaxial pre-strained circular actuator model was built. The Yeoh strain energy potential and the collocation method are used for describing the large strain actuation response and stress distribution. The study in this paper has shown that: the stress and the stretch distributions in the passive region of the DE actuator depend on the radial distance from the center at the calculation point of the passive region and the magnitude of the applied voltage; with the same excitation applied voltage, we can get a larger deformation actuation by choosing an appropriate pre-stretch ratio; the influence of the non-ideal material has seriously affected the actual deformation of the DE actuators. This analytical model has a reference potential for the design optimization of high performance DEA systems and the model-based control of the DEA robot.     

曲面混凝土构件内弧粘贴FRP弦剥离效应

进行了26个曲面构件的FRP-混凝土界面粘贴试验, 研究了混凝土强度、FRP粘贴层数、FRP粘贴长度与构件曲率对粘贴强度、界面应变与破坏机理的影响。研究结果表明: 曲面混凝土构件内弧粘贴FRP易出现3种破坏形态: 弦剥离破坏、FRP在裂缝处被拉断和FRP在试件裂缝一侧发生剥离, 其中构件曲率越大, 越容易发生弦剥离破坏, 小曲率构件多发生FRP拉断破坏; 随外荷载的增大, FRP应变峰值有一个向后传递的变化过程, 说明沿纤维长度方向的FRP并不是全部参与工作, 存在一个有效工作(粘贴) 长度; 对本试验数据采用虚拟零点方法分析得出, 曲面混凝土构件内弧粘贴FRP有效粘贴长度约为14 cm; 曲率对粘贴强度影响显著, 曲率增大, 纤维应变梯度增大, 有效粘贴长度变小, 粘贴强度降低; 曲率相同时, 纤维层数越多, 沿纤维方向应变分布越均匀, 粘贴强度越大, 但是这一增长并非与FRP层数成线性关系, 2层纤维粘贴强度约为1层的1.5倍; 当纤维层数增加时, 粘贴层法向应力增大较快, 试件更易发生弦剥离破坏, 这种破坏是由法向粘贴应力与面内剪应力的耦合效应引起的; 粘贴层应力函数可用内弧曲率圆心角的余弦函数表示, 当矢高分别为30、60、90 mm时, 构件平均误差分别为7.7%、2.4%与8.8%, 因此, 函数精度较高。      

轴对称模锻过程的CAS／CAD系统

本文运用上限元法分析了轴对称水平非对称锻件的模锻过程,建立了相应的计算机模拟系统(GAS);为了获得预成形毛胚的理想形状,作者运用计算机进行工序正向模拟之后,又进行了工序反向模拟,经实验验证,计算数据是正确的。