利用宏程序和成形铣刀加工方形弧面保持架兜孔

介绍某型圆柱滚子轴承自锁实体保持架采用方形弧面兜孔的结构及特点,通过利用宏程序对保持架兜孔方形轮廓进行数控铣削加工,并采用成形铣刀加工出保持架梁侧壁上的弧面部分,成功完成了该类型保持架的加工,各项指标满足要求。     

铝合金矩形截面内高压成形圆角充填行为研究

为了研究铝合金矩形截面内高压成形过程圆角充填行为,设计制造了专用试验装置,测试充填过程中圆角半径与内压的定量关系及其润滑条件影响,分析直边区与圆角区的过渡处开裂的机理,并对内压理论计算值与试验值进行对比。结果表明:充填过程中随圆角半径的减小,所需内压逐渐增大。当相对圆角半径大于5时,圆角半径变化趋势较快;而当相对圆角半径小于5时,变化趋势逐渐平缓。润滑条件对圆角充填影响较大,润滑的改善使成形相同圆角所需内压降低,极限圆角半径减小。从截面直边区的中点到直边区与圆角区的过渡点等效应力逐渐增大,所以过渡点附近最易发生壁厚过度减薄甚至开裂。对于硬化材料,未考虑材料硬化的内压理论计算值明显小于试验值,内压理论计算时必须使用材料硬化后的流动应力。     

盒形件冲压拉深成形数值模拟研究

通过对盒形件冲压拉深成形过程进行数值模拟,得到成形后零件的成形极限图和侧壁厚度分布图,进而研究冲压拉深时压边间隙和凸模圆角半径对盒形件成形质量的影响。研究结果表明,压边间隙为1. 08 mm,凸模圆角半径为6 mm时,能够明显改善盒形件的冲压拉深成形质量。     

推力球轴承保持架冲压成形和回弹的模拟分析

利用有限元软件ANSYS/LS-DYNA的显式-隐式连续求解功能,模拟推力球轴承保持架的冲压成形和回弹全过程,可以直观地观测到保持架板料的弯曲变形情况、板料厚度的变化情况、板料应力分布情况以及最后的保持架回弹情况等等,可以作为优化设计可靠的参考依据,为进一步的结构改进提供合理的技术指导.     

基于Taguchi方法的镍涂层薄板冲压工艺参数研究

从厚度减薄和厚度分布角度出发,结合Taguchi实验设计方法,建立了镍涂层薄板的数值仿真模型,分析研究了凹模圆角半径、压边力、摩擦系数等工艺参数对镍涂层薄板冲压成形性能的影响,最终确定了各个工艺参数对成形质量(厚度变化)的影响及其相对影响程度。同时,通过对比仿真数据与实验结果,验证了该仿真模型的有效性。     

基于ANSYS的球壳开孔接管区应力分析

球壳开孔接管区的应力高且分布状况复杂。利用ANSYS软件,通过获取应力分布云图及线性化处理提取的各类应力,探讨了过渡圆角半径对球壳开孔接管区应力的影响。结果表明,球壳与接管连接处存在明显的应力集中。采用圆角过渡可以降低应力集中系数。只有圆角半径较大时,应力集中系数才会显著降低,并且主要是降低了其中的弯曲应力和峰值应力。当圆角半径增加到一定程度,应力集中系数降低极其缓慢。结果为工程实际中球壳开孔接管区圆角半径的选取提供借鉴。     

深沟球轴承冠形保持架结构参数对其性能的影响

基于滚动轴承动力学理论,建立了冠形保持架深沟球轴承动力学微分方程组,采用预估-矫正变步长积分法对方程组进行求解。以6210深沟球轴承为例,分析兜孔修形半径、爪部长度对保持架运转平稳性和强度的影响,结果表明:保持架运转平稳性随兜孔修形半径增大先增大后减小,随爪部长度增大无变化;保持架应力随修形半径增大先减小后增大,随爪部长度增大先减小后增大;保持架变形量随修形半径增大而增大,随爪部长度增大先增大后减小。     

冲击工况下高速圆锥滚子轴承保持架动力学分析

基于圆锥滚子轴承零件受力模型及润滑理论建立适用于冲击工况的轴承保持架动力学模型,在此基础上,考虑联合载荷和冲击载荷的作用,基于ANSYS/LS-DYNA分析了兜孔间隙和引导间隙对保持架动态特性的影响.结果表明:冲击载荷将使保持架涡动半径增大,质心运动不稳定,保持架应力增大;随兜孔间隙增大,保持架质心运动轨迹的涡动半径增...     

车制实体保持架缓冲槽结构兜孔工艺分析

圆柱滚子轴承保持架的制造精度及精度稳定性是轴承能够适应各种工况要求、平稳运转的关键要素。兜孔是保持架的主要工作部位,车制实体保持架兜孔通常为直兜孔和铣、拉成形兜孔2种结构,根据保持架及兜孔的结构、尺寸范围,一般以拉削、线切割等工艺方法实现兜孔加工。为进一步提高保持架的兜孔位置精度和表面质量,优化了兜孔设计结构,将保持架兜孔4个顶角由过渡小圆弧改为缓冲槽结构,兜孔加工将原工艺"钻、铣孔→拉方孔"工序合并,只需要"钻、铣兜孔"一道工序完成,大幅度提高了保持架制造精度。     

40CrNiMoA外悬梁保持架加工工艺改进

介绍40CrNiMoA钢制外悬梁保持架的结构和加工难点,针对传统圆盘形错齿三面刃铣刀加工无法满足保持架梁宽变动量和兜孔表面粗糙度要求的问题,重新设计了凹R成形铣刀和工装夹具,检测数据表明,改进后工艺满足了加工要求。     

拼焊板弯曲回弹的理论与试验研究

在平断面假设、纯弯曲假设、拼焊板不考虑焊缝等一系列较为合理的假设条件下,推导了拼焊板弯曲回弹解析模型。推导考虑材料有指数硬化特性和中性层的移动及应力应变中性层的不重合性等问题,但没有考虑包辛格效应的影响和中性层的转动问题。针对这个弯曲回弹公式,编程计算差厚(1.6 mm/0.8 mm)拼焊板的回弹值,并采用75°V形自由弯曲试验进行了验证;对拼焊板的弯曲回弹进行了理论分析,提出了拼焊板相对弯曲半径的概念。     

管材拉弯工艺及数值模拟分析

拉弯是管材弯曲成形的重要工艺方法,采用有限元分析软件ANSYS/LS-DYNA对不同工艺参数下的管材拉弯成形过程进行了数值模拟,通过改变相对弯曲半径R/D和相对弯曲厚度t/D,分析了拉弯工艺参数对成形过程的影响。研究结果表明:通过增大相对弯曲半径R/D或增大相对弯曲厚度t/D,降低弯曲件的等效应力,可以有效控制弯曲件壁厚的变化,有助于提高管材拉弯成形的质量。     

重载汽车转向节臂的强度分析及结构优化

重载汽车转向节臂结构复杂,承受弯扭组合变形的作用,强度分析至关重要。通过ANSYS软件对汽车转向节臂在承受非线性载荷时进行模拟分析,采用参数化命令得到了转向节臂的等效应力分布规律。通过修改应力值较大区域处的圆弧半径,对转向节臂进行结构优化设计,模拟显示,改进后的结构应力分布较为合理,最大应力值明显减小,为转向节臂的结构设计提供了理论参考。     

板料成形反向模拟精度修正法

传统的板料成形反向模拟法(Traditional inverse analysis method, TIAM)没有考虑变形历史对成形过程的影响,使得反向模拟法计算的应力值与实际情况有较大偏差。金属在流经凹模圆角时受到强烈的弯曲—反弯曲作用,并且凹模圆角处往往是应力集中的区域,能否较为准确地描述该区域变形历史,关系到反向模拟法应力/应变计算精度。针对反向模拟法无法准确预测成形零件应力分布的缺点,提出一种快速搜索流经凹模圆角区域单元的方法,对该部分单元进行应力修正。采用一种高效的多步加载应力应变本构关系模型,避免了增量有限元法应力应变更新算法的复杂性,同时充分考虑了凹模圆角对金属变形历史的影响。NUMISHEET’93 U形件弯曲的标准考题中,通过与增量有限元分析软件ABAQUS/Standard计算结果的比较,验证了采用所提出的多步加载本构关系模型可以有效地反映变形历史的影响,获得更为接近真实情况的应力分布。     

A study on the bending stress of the hollow sun gear in a planetary gear train

Generally, planetary gear type traveling reduction gear is composed of multiple planetary gear stages and has a hollow sun gear in the last stage planetary gear. In designing reduction gear, it is important to evaluate accurately the bending stress at the tooth root of the sun gear as the sun gear is the weakest component in the reduction gear system. Although bending stress can be calculated easily using gear standard codes such as the American Gear Manufacturers Association (AGMA) and International Organization for Standardization (ISO) 6336 for almost all gears, meticulous calculation is needed for the hollow sun gear because of its low backup ratio (rim thickness divided by tooth height) and comparatively large root fillet radius. In this study, a finite element analysis (FEA) is carried out to investigate the effect of rim thickness and root fillet radius on bending stress at the tooth root of the hollow sun gear. In standard codes, bending stress at the tooth root is calculated linearly with a constant slope for the backup ratio below 1.2. However, the effect of the rim thickness on bending stress is more complex in the planetary gear system. Bending stresses calculated by FEA with various backup ratios and root filler radii are compared with the bending stresses calculated by the standard codes.     

柔性管板计算方法与几何尺寸优化

利用ANSYS 15.0软件对柔性管板进行热-应力耦合分析,得到柔性管板整体应力分布规律,对柔性管板厚度、换热管中心间距、过渡圆角半径进行优化,并对国内外管板计算方法进行对比分析.结果表明:西德AD方法计算出的管板厚度最小;随着柔性管板厚度的增加,薄膜应力先减小后增大,薄膜加弯曲应力逐渐增大;随着换热管中心间距的增大,...     

The pure plastic bending of laminated sheet metals

This paper deals with the pure bending of bonded laminated metals under plane strain conditions. Each laminate is classified by its initial yield strength, work-hardening characteristics and its percentage thickness in relation to the whole sheet. Computer programs have been developed which enable the sheet thickness, the magnitude of the bending moment and the distribution of the radial and tangential stress across the sheet to be calculated as a function of the radius of curvature of the bent sheet. Detailed calculations were performed for rigid non-strain-hardening bi- and tri-metals. The results indicated that the relative position of the strong and weak laminates in the sheet determined whether the overall sheet thickness increased or decreased during bending and whether the bending process was stable, i.e. took place under an increasing moment. Incorporating work hardening into the analysis increased the computation time but generally yielded similar results. A few bending experiments on laminated sheet confirmed the theoretical predictions.Detailed calculations were also performed for a rigid-strain-hardening mono-metal adopting a simple Bauschinger effect. These results were compared with the same material without the Bauschinger effect.     

双圆弧齿轮的弯曲应力分析

基于任意转角位置的双圆弧齿轮齿廓数学模型,运用Pro/E软件对双圆弧齿轮的弯曲应力进行了有限元分析,讨论了双圆弧齿轮各段弯曲应力的分布情况,并着重研究了轮齿的不同构成参数对齿轮弯曲应力的影响。其分析结果将为双圆弧齿轮设计、参数优化选择等提供参考依据。     

Finite element analysis of sided coined-bead technique in precision V-bending process

To fabricate the precision V-bent parts, the bending angle, inner bending radius, and outer bending radius are strictly required. These requirements result in a processing difficulty especially for the difficult-to-bend material, such as high-strength steel. In the present study, the finite element method (FEM) and laboratory experiments were used to investigate the precision V-bending process. An innovation of sided coined-bead technique was proposed for preventing the spring-back and spring-go. The conventional coined-bead technique was also investigated. Based on the stress distribution analysis, the results revealed that the mechanism of the precision V-bending process, conventional coined-bead technique, and sided coined-bead technique were clearly identified. In the precision V-bending process, the conventional coined-bead technique could only prevent the spring-back. In contrast, the sided coined-bead could prevent both the spring-back and the spring-go by setting a suitable geometry and position. The FEM simulation results showed a good agreement with the experimental results with reference to the bending forces and bending angles.     

时变位姿下行星齿轮传动系统动应力计算模型及其参数影响研究

考虑行星轮系内部非惯性和机体时变位姿外部非惯性的综合影响,推导了任意时变位姿下带有机匣的行星轮系构件运动方程,计入时变啮合刚度、啮合误差、侧隙和啮入冲击,建立了时变位姿下行星齿轮传动系统级动力学模型,并采用精细积分时程法（Precision integration method,PIM）求解得到了动态啮合力序列。根据齿间载荷分配关系进一步得到单齿啮合力序列。最后结合修正Heywood公式与Hertz公式构建了时变位姿下行星齿轮传动系统齿根弯曲动应力和接触动应力计算模型,并研究了机体平飞、滚转和筋斗位姿参数对接触动应力、弯曲动应力的影响规律。结果表明：不同时变位姿参数对弯曲、接触动应力影响显著,且对不同齿轮副影响不同,即加剧了齿轮副间承载不均;筋斗运动角速度对动应力影响比平飞加速度、滚转角速度以及筋斗回转半径对其影响复杂;机匣对动应力影响随加速度增大而增加。研究成果为时变位姿下行星齿轮传动动应力计算与高可靠性设计提供了理论依据。