工艺参数对三维非轴对称管件缩径旋压成形的影响

以6061T1(挤压态及退火态)铝合金为研究对象,探讨工艺参数对三维非轴对称管件缩径旋压成形的影响。结果表明,当材料状态及其他工艺参数相同时,与轴对称零件相比,偏心及倾斜类零件的极限名义缩径量要小得多;轴对称件所能采取的进给比下限最低,而倾斜件的进给比下限最高;当旋转圆角半径过小时,会使工件表面粗糙度值变大,甚至出现破裂现象;旋轮直径对极限名义缩径量的影响不大。当工艺参数选择不合理时,工件口部或起旋点附近易产生破裂现象,为危险截面所在位置。     

三维非轴对称零件旋压成形机理研究

提出采用旋压技术直接加工各部分轴线间相互平行或成一定夹角的三维非轴对称薄壁空心零件的工艺方法,探讨了该成形技术的工作原理、成形过程的特点及变形机理,并预测了其推广应用前景。提出的旋压成形装置可使旋轮在随机床主轴作回转运动的同时,沿垂直于机床轴线方向作径向进给运动。     

三维非轴对称零件旋压成形工艺及设备

介绍了三维非轴对称零件的旋压成形工艺及设备，利用该设备不但可以加工普通的轴对称零件，还可加工传统旋压成形方法无法加工的三维非轴对称零件。另外，在进行轴对称零件的加工时，既可进行普通旋压，又可以进行强力旋压，还可完成有芯模或无芯模的旋压。     

滚压装配变形力计算与工艺实现

将挤压变形成形方法应用于带式输送机托辊组件的装配中，对托辊组件滚压变形装配原理和工艺实现进行了研究，运用主应力法推导了滚压变形力的计算公式，成功地设计了托辊组件滚压变形装配专用机，在满足装配精度的同时，大大地提高了生产效率。     

转子静偏心时异步电机径向力特性分析

针对异步电机转子静偏心时产生的径向力引起的电机振动和噪声问题,通过有限元软件,采用近似解析法和电磁场数值解相结合的方式,对异步电机的径向力的特性进行了分析.首先,通过麦克斯韦应力求解公式推导出了异步电机转子静偏心时主要径向力的阶次和频率分布;然后利用ANSYS有限元软件求解了异步电机转子静偏心时电机气隙磁场的分布情况,最后利用Matlab结合电机径向力计算公式得出了此时电机径向力的分布特性,结合时空傅里叶分解得到了电机转子静偏心时径向力频率、阶次和幅值的分布情况.研究结果表明,该理论算法与有限元算法相结合的计算方式对异步电机转子静偏心时径向电磁力的分布做出了较为准确的分析.     

倾斜管件多道次缩径旋压成形的数值模拟及试验

以6061T1(退火态)铝合金为研究对象,以MSC.MARC软件为分析手段,采取有限元法对三维非轴对称倾斜管件多道次缩径旋压过程进行数值模拟,并利用网格圆及显微组织的变化从试验的角度验证模拟所得到的应变分布规律。结果表明,倾斜使得工件的应力应变呈不均匀分布规律;等效应力沿轴向呈分层分布的特点,在口部达到最大值;等效应变沿周向0°～180°域逐渐减小,在0°域存在最大值,180°域存在最小值;沿轴向从起旋处到口部,等效应变在0°域具有逐渐增大和在180°域具有逐渐减小的特征。由于返程旋压的明显增厚效应,多道次旋压时,工件变形中间部位壁厚增加。多道次缩径旋压时工件变形中间部位壁厚变化规律的试验结果与模拟结果的相对误差不大于10%,说明所建立的有限元模型是合理可靠的。在理论分析及试验研究的基础上,成功研制出倾斜类汽车排气歧管样件。     

药筒旋压变形工艺参数选取分析

旋压工艺参数的确定是强力旋压加工的一个关键因素。各种工艺参数的确定、各工艺参数之间如何合理配合以及它们对旋压质量的综合影响都是需要解决的难题,根据实际经验以及旋压仿真模拟结果进行比较,对旋压变形关键工艺参数的选取进行了分析和确定。     

薄壁管体缩径旋压变形特性分析

新研制的整体式无心轴托辊是在薄壁管体两端直接缩旋出轴颈得到的,通过托辊缩径旋压试验,本文总结了薄壁管体的变形过程,分析了薄壁管体缩径旋压塑性变形规律,缩径旋压的成形机理,缩径旋压过程中金属性能的变化,以及缩旋中缺陷的产生及控制方法.     

一种筒形薄壁件旋压成形的控制

在生产实践的基础上 ,对旋压成形的薄壁筒形件精度进行了分析 ,并找到了影响其变形的主要因素及其消除变形的工艺方法     

轴对称拉深成形法兰区起皱失稳变形能及临界压边力

在平面应变假设条件下,对轴对称拉深成形法兰区的起皱失稳问题进行了理论分析。首先采用数学方法,将以积分形式表示的应力解析式进行了简化。在此基础上,进一步简化了起皱过程中变形能的计算式。给出的算例表明,对起皱过程中的变形能分别以简化后的计算式和以原积分式进行计算,其结果误差很小,相对误差小于0.8%。该起皱失稳临界压边力的计算和分析简化方法有助于给出简明和符合实际的起皱判据。     

ANALYSIS ON THE SPINNING FORCES IN FLEXIBLE SPINNING OF CONES

Flexible spinning is a new type of spinning process where spin-forming is performedwithout using a mandrel. Combining shearing and rolling processes, the calculation formulas of thespinning forces in flexible spinning of cones is presented. The effects of the main processing parame-ters, such as gripping force G applied to the blank by the inner roller, the feed rate of rollers f and theroundness radius of outer roller r_o, on the spinning forces are analyzed experimentally and theoreti-cally.     

ANALYSIS OF MECHANICS IN BALL SPINNING OF THIN-WALLED TUBE

Ball spinning is applied to manufacturing thin-walled tube with high precision and high mechanical properties. On the basis of plastic mechanics, by simplifying ball spinning of thin-walled tube as plane strain problem, slab method is used for the purpose of calculating the contact deformation pressure. The spinning force components, the torsional moment, the deformation power and the deformation work are calculated further as well. The influence of the two important process parameters such as the feed ratio and the ball diameter on the spinning force components is analyzed in order to further control the spinning force components by regulating the two process variables during the ball spinning process. The stress and strain state in deformable zone as well as mechanics boundary conditions in ball spinning are obtained. The effect of the three spinning force components on the formability of the spun part is analyzed and validated through the ball spinning experiments. The theoretical and experimental results show that the radial spinning component plays a significant role in ball spinning of thin-walled tube, and the mechanics situation in backward ball spinning contributes to enhancing the plasticity of the metal material, but that in forward ball spinning contributes to advancing the axial flow of the metal material.     

MECHANISM RESEARCH FOR 3D NON-AXISYMMETRIC THIN-WALL TUBE OFFSET SPINNING

Difference of offset spinning with conventional symmetric spinning is analyzed. A 3D FEM model for offset tube neck-spinning is established and the spinning process is simulated by means of ANSYS software. Dynamic boundary and contact problems in simulation are solved. Transient stress distribution of contact area, transient strain distribution of nodes in typical section and strain distribution of the workpiece at last are attained, the place and the cause of crack are analyzed. Strain variation curves with time of offset spinning and conventional spinning are compared. It shows the mechanism difference between offset spinning and conventional spinning. In addition, simulation results show how strain distribution of typical section, thickness of some typical nodes, axial extension in left section and force of three rollers change with time. According to the study of the variation curve, material flow law along radial, tangential and axial direction is attained and the whole spinning process is studied. The simulation results discover that offset distance is the key to manufacture offset non-symmetric tube, and process parameters change with spinning angle. Experiment data really reflect different process parameters' influence on conventional symmetric and offset spinning force. Experiments accord well with simulation.     

碟形容器封头冷旋压过程三维有限元数值分析

依据有限元理论,对冷旋压碟形封头的变形机理进行了分析,应用ANSYS软件对其变形过程进行了数值模拟研究,得出了封头在不同位置成形时应力、应变的分布规律。分析了应力、应变对变形的影响,计算了旋压力,为优化工艺参数提供了有效方法和可靠依据。     

内压作用下波纹换热管应力分析

用有限元法和实验应力分析法对波纹换热管在内压作用下的应力分布规律进行探讨。结果表明,光管加工成波纹换热管后,在波峰过渡处与波谷过渡处均产生了较严重的应力集中现象,最大应力出现在波谷过渡处附近,比相应条件下光管中的应力大许多,且在管的厚度方向有应力梯度存在。通过分析指出影响波纹管上最大应力强度值的因素,并得出最大应力强度值最小时的优化波形。     

Finite element simulation and experimental investigation on the forming forces of 3D non-axisymmetrical tubes spinning

3D non-axisymmetrical tube (NAT) spinning is a kind of new spinning technology, which breaks through the restriction that only axisymmetrical hollow parts could be produced by traditional spinning technology. The research on the spinning force aims to optimize the machine design and the processing parameters selection. The neck-spinning process of the 3D NAT is simulated by 3D elastic–plastic finite element software, MARC. The characteristics of the neck-spinning force of 3D NAT are compared with that of the axisymmetrical tube (AT) spinning. The effect of the main forming parameters, such as offset amount, oblique angle, nominal reduction of blank radius, feed rate and path direction, on the spinning forces have been studied theoretically and experimentally. It shows that during 3D NAT spinning, the spinning forces varies periodically with the revolution angle of the roller around the blank; the spinning force during backward path spinning is greater than that of forward path spinning. The simulation results conform well to the experimental ones.     

液-固挤压Al2O3sf /LY12复合材料管材成形过程的数值模拟

针对液-固挤压复合材料管材的成形过程,采用热刚塑性准耦合有限元法进行了数值模拟,以揭示其塑性变形行为.通过自行开发的有限元模拟系统软件,利用网格重新划分技术,得到了复合材料液-固挤压变形过程中的应力场、应变场及变形力,并对有关问题进行了分析.与试验结果相比较,验证了该系统的可靠性,为保证制件成形质量和合理选择工艺参数提供了理论依据.     

三维体积成形过程的并行无网格法仿真分析

将显示无网格法引入三维体积成形仿真过程,设计了基于再生核质点法(Reproducing kernel particle method, RKPM)无网格法理论的并行算法。在前处理过程中,采用了多层次二分法对几何模型进行分区;在仿真计算过程中,设计基于消息传递机制的粗粒度并行程序,针对接触搜寻算法的特点,提出了接触问题并行化的新策略。并编制了相应的程序,成功地对三维体积成形问题进行了求解,准确地处理了网格严重畸变的问题,并验证了该算法的准确性和有效性。     

摆线针轮行星传动的齿形修正及受力分析

B.H.库德略夫采夫提出的关于摆线针轮行星传动中摆线轮与针齿啮合时的受力分析方法,由于未考虑摆线轮齿形修正的影响,在工程计算中带来极大的误差。本文在讨论摆线轮齿形合理修正方式的基础上,提出了一种能适用于修正齿形进行有隙啮合,因而符合工程实际条件的较准确的力分析方法和计算公式。