三维非轴对称偏心类管件旋压成形时的变形力分析

采用主应力法建立了三维非轴对称偏心类薄壁管件旋压成形时的变形力的理论计算公式,并对旋轮公转角度γ、道次偏移量δ等成形工艺参数对旋压力变化的影响进行了理论分析。结果表明,在偏心类管件旋压过程中,旋压力随旋轮公转角度γ作周期性变化,其变化的幅度取决于道次偏移量δ的大小。对工件道次偏移量δ、旋轮进给比f和名义压下量Δ等主要成形工艺参数对最大旋压力的影响进行了理论分析和试验研究,理论计算结果与试验结果吻合较好。     

ANALYSIS ON THE SPINNING FORCESN IN FLEXIBLE SPINNING OF CONES

Flexible spinning is a new type of spinning process where spin-forming is performed without using a mandrel. Combining shearing and rolling processes, the calculation formulas of the spinning forces in flexible spinning of cones is presented. The effects of the main processing parameters, 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 ro, on the spinning forces are analyzed experimentally and theorelically.     

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.     

旋压成形有限元分析中旋轮被动转动问题的研究

旋压成形中旋轮被动转动是一个重要的边界条件，在有限元分析中需要时实确定旋轮的转速。接触区不同位置摩擦力的大小和方向不一致，旋轮和坯料接触区的摩擦力综合作用引起旋轮被动转动。利用在每个增量步内转矩平衡给出确定旋轮的转速的原则，通过反复迭代求解每个增量步内旋轮的转速，通过事例验证所提方法的可行性。     

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。     

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。     

旋压成形带内筋筒形件的工艺研究及数值模拟

针对旋压成形带内筋筒形件的工艺进行试验研究和数值模拟.依据实际试件的尺寸及成形情况对边界、接触、摩擦以及空间运动等条件进行确定.建立三维有限元数学模型,分析在不同壁厚减薄率和旋轮进给率等工艺参数下内筋的成形情况和应力、应变及旋压力的变化规律.对试件在成形试验时出现的表面剥离、裂纹等缺陷进行预测和初步分析,可提高工作效率并降低研发成本,为进一步深入研究带内筋筒形件旋压工艺的成形机理和变形特点打下了良好基础,为优化工艺参数提供了有效方法和可靠依据.     

ON THE PERFORMANCE ANALYSIS OF FLEXIBLE MAGNETIC ABRASIVE BRUSH

Magnetic abrasive finishing (MAF) of alloy steel workpiece with unbounded magnetic abrasive particles (UMAPs) indicates that the surface finish in the range of nanometer can be achieved. Important controllable four process parameters have been identified which are as current to the electromagnet, machining gap, abrasive size (mesh number), and number of cycles. Experiments have been planned using design of experiments technique. Based upon the results of response surface methodology and analysis of variance (ANOVA), it is concluded that magnetic flux density that depends on current to the electromagnet and machining gap, is most influencing parameter followed by grain size and number of cycles. The surface roughness profile generated during the MAF process has been discussed. To understand the cutting mechanism of magnetic abrasive finishing process, scanning electron microscopy (SEM) and atomic force microscopy (AFM) of the machined surfaces have been carried out. The correlation between surface finish and material removal has also been established.     

ON THE PERFORMANCE ANALYSIS OF FLEXIBLE MAGNETIC ABRASIVE BRUSH

ABSTRACT

Magnetic abrasive finishing (MAF) of alloy steel workpiece with unbounded magnetic abrasive particles (UMAPs) indicates that the surface finish in the range of nanometer can be achieved. Important controllable four process parameters have been identified which are as current to the electromagnet, machining gap, abrasive size (mesh number), and number of cycles. Experiments have been planned using design of experiments technique. Based upon the results of response surface methodology and analysis of variance (ANOVA), it is concluded that magnetic flux density that depends on current to the electromagnet and machining gap, is most influencing parameter followed by grain size and number of cycles. The surface roughness profile generated during the MAF process has been discussed. To understand the cutting mechanism of magnetic abrasive finishing process, scanning electron microscopy (SEM) and atomic force microscopy (AFM) of the machined surfaces have been carried out. The correlation between surface finish and material removal has also been established.     

基于有限元的光固化快速成形中零件变形研究

以光固化快速成形过程中的零件变形为研究对象,详细分析了收缩力产生的根源及其作用原理,根据树脂固化时必然产生的收缩及层累加的特点,提出了收缩力、面分布载荷的概念;根据零件在成形过程中结构变化的特点,提出时变刚度的概念。基于此,建立了零件成形过程中的力学模型,利用有限元法分析了零件变形的趋势,揭示了成形过程中零件变形的本质问题。通过试验研究了零件的变形问题,试验结果证明了理论分析的正确性。由此提出了改进扫描工艺的分区域扫描策略,显著的减小了成形过程中零件的变形,提高了成形零件的精度。     

单轮对轮轨蠕滑力试验研究

利用原型尺寸单轮对试验装置和滚振试验台,进行单轮对（货车）运动过程中轮轨之间蠕滑力试验研究,试验中考虑到轮对位置和轮轨表面之间有污染因素影响。试验结果反映了轮轨之间蠕滑力和轮对运动位置（轮对横移和摇头角）之关系,对其进行了详细讨论。并对部分试验结果同Kalker三维弹性体非赫兹滚动接触理论计算的结果作了比较。     

CONSIDERATION OF THE FORM OF THE UNDEFORMED SECTION OF CUT IN THE CALCULATION OF MACHINING FORCES

For the calculation of machining forces in turning processes, the empirical equation of Victor and Kienzle has been established as a common model. However, the model has some constraints. The undeformed chip thickness has to be higher than 0.1 mm and the ratio of undeformed chip width and undeformed chip thickness has to be higher than four. This means that the equation cannot be used for several combinations of process parameters. This paper shows an approach to calculate the machining forces for any form of undeformed sections of cut based on the approach of Victor and Kienzle. In order to achieve this, the undeformed chip thickness and the undeformed chip width are defined in a new way. Furthermore, the direction of chip flow is considered to determine the feed and passive force components.     

ANALYSIS OF CREEP FORCES OF WHEEL/RAIL

ＮＯＴＡＴＩＯＮＳｙ1———Ｌａｔｅｒａｌｄｉｓｐｌａｃｅｍｅｎｔｏｆｃｅｎｔｅｒｏｆｗｈｅｅｌｓｅｔｖ1———Ｌａｔｅｒａｌｖｅｌｏｃｉｔｙｏｆｃｅｎｔｅｒｏｆｗｈｅｅｌｓｅｔφ———Ｙａｗａｎｇｌｅｏｆｗｈｅｅｌｓｅｔω———Ｙａｗａｎｇｌｅｖｅｌｏｃｉｔｙｖ———Ｆｏｒｗａｒｄｓｐｅｅｄｏｆｗｈｅｅｌｓｅｔ,ｏｒｎｏｍｉｎａｌｒｏｌｌｉｎｇｓｐｅｅｄｏｆｗｈｅｅｌｓｅｔｒｉ———Ｒａｄｉｕｓｏｆｉｎｓｔａｎｔｒｏｌｌｉｎｇｃｉｒｃｌｅｏｆｗｈｅｅｌｒ0 ———Ｒａｄｉｕｓｏｆｒｏｌｌｉｎｇｃｉ…     

高精度RV传动的受力分析及传动效率

为了给新型ＲＶ传动的优化设计提供科学依据，论述了其原理和特点，提出了该传动名义力分析计算模型并给出了计算实例，最后进行了效率分析计算。     

柔性结构振动控制的初步分析与试验研究

采用智能结构的原理和方法,对压电元件用于柔性结构振动控控制的有关问题进行了初步探讨。对压电驱动器与结构的匹配关系进行了理论分析,对模态传感－驱动器对在柔性悬臂板结构中的布置数量和位置进行了优化设计,并对结构振动进行了控制试验,验证了该方法的有效性。     

基于加速度反馈的柔性关节机械臂接触力控制

针对柔性关节机械臂从自由空间运动控制过渡到约束空间力控制的过程中,存在冲击、震荡甚至不稳定等问题,利用加速度传感器反馈控制,为柔性关节机械臂的接触力控制在较宽的带宽内提供阻尼,克服了利用单纯速度反馈控制带宽窄的局限。对柔性关节机械臂的接触力控制进行建模和基于加速度反馈的控制策略分析,并在柔性关节机械臂上进行了接触力控制的试验研究。结果表明,这种方法有效。     

平面柔性并联机器人动力学建模

利用有限元理论研究柔性并联机器人动力学建模的理论和方法,分析各支链的弹性位移及其耦合关系,建立柔性并联机器人系统的运动约束条件和动力约束条件。综合考虑构件的分布质量、集中质量以及杆件的剪切变形、弯曲变形、拉压变形和横向位移的影响,运用运动弹性动力学理论和Lagrange方程,推导出平面柔性并联机器人的动力学方程。以平面3-RRR柔性并联机器人为例,说明该动力学模型能正确反映柔性并联机器人的弹性振动特性,杆件的弹性变形对机器人动平台的位置误差和方向误差具有重要影响。     

考虑油膜惯性力时Jeffcott转子—挤压油膜阻尼器系统的突加不平衡响应特性

转子系统的不平衡呈可能由于偶然的原因而突然增大，转子系统在突加不平衡作用下的响应特性是一个很值得关心的问题。本文首先建立转子系统的微分方程，然后在考虑油膜惯性力的情形下，分析了转子的突加不平衡响应，并和不考虑惯性力的结果进行了比较。研究表明，考虑惯性力后，对常转速下的突加不平衡响应，瞬态响应的时间和振幅都减小了。对加速通过双稳态响应区时的突加不平衡响应，如突加不平衡发生在双稳态响应区之前，响应将沿     

EFFECT OF CRYSTALLOGRAPHIC ORIENTATION ON CUTTING FORCES AND SURFACE FINISH IN DUCTILE CUTTING OF KDP CRYSTALS

In order to investigate the influence of material anisotropy in ductile cutting of Potassium Dihydrogen Phosphate (KDP) crystals, experiments of face cutting of (001) plane of KDP crystals are carried out by using an ultra-precision lathe with a single point diamond tool. The cutting forces, surface finish, and surface roughness in all crystallographic orientations of the machined surface are measured, and a power spectrum analysis method is used to reveal the cutting force patterns. The experimental results show that the cutting forces and surface roughness vary greatly with different crystallographic orientations of KDP crystal, and that amplitude variation of cutting forces and surface finish is closely related with the cutting parameter of the maximum undeformed chip thickness. With the maximum undeformed chip thickness below 30 nm, the amplitude variation of cutting force and surface finish is minimized, and a super-smooth surface with consistent surface finish in all the crystallographic orientations can be achieved. The surface roughness is 2.698 nm (Ra) measured by Atomic Force Microscope (AFM). These findings provide criteria for achieving a large-scale KDP crystal with consistent super-smooth surface using ductile cutting technology.     

柔性耦合系统主动隔振策略研究

针对设备上楼的柔性安装问题,把设备的安装基础建模为柔性基础,建立了柔性基础　上主动隔振系统模型,考虑了设备、隔振器、作动器和柔性基础的耦合作用,用传递导纳来　描述作动器的控制力,采用导纳综合法推求了主被动隔振的统一的功率流传递控制式,探讨　了ＰＩＤ等控制方法的主动控制策略,从而实现了控制ＦＢＲＥ系统若干阶模态振动的目的。