一种空实向结构橡胶牵引球铰圆度减小的方法

针对空实向结构橡胶牵引球铰,设计出新型弹性多瓣椭圆孔缩径工装（简称椭圆孔缩径工装）及相应预压缩工艺,以解决空实向结构橡胶牵引球铰圆度过大的问题。试验结果表明：与传统轴向圆孔挤压工艺空实向结构橡胶牵引球铰相比,新型椭圆孔缩径工艺空实向结构橡胶牵引球铰圆度减小82%,径向刚度略微增大,粘合性能和耐疲劳性能未发生明显变化。新型椭圆孔缩径工艺可用于空实向结构橡胶牵引球铰的批量生产。     

弹性球铰胶料配方与性能研究

选用少量反式聚异戊二烯替代天然橡胶、少量白炭黑替代炭黑制备了弹性球铰橡胶胶料,研究了不同配方胶料的弹性球铰径向静刚度、轴向静刚度、扭转静刚度和疲劳性能等。结果表明,选用10份白炭黑替代改性炭黑、10份反式聚异戊二烯替代天然橡胶后弹性球铰2向刚度、静刚度和疲劳性能圴明显提升。     

半沙漏橡胶弹簧低温性能研究

对轨道车辆二系半沙漏橡胶弹簧的低温性能进行研究.结果表明:半沙漏橡胶弹簧低温下的垂向切线刚度变化率受垂向预载影响明显,且小于动刚度变化率;横向静刚度受温度影响较大,与是否预载关系不大;为了更接近实际情况,产品低温试验必须在有预载的情况下进行;橡胶制品在低温下的刚度性能恢复能力取决于制品厚度及受载方式;低温状态下车辆的舒适性下降,但随着车辆的运行,橡胶制品在振动状态下逐渐恢复弹性.     

橡胶轴箱定位器的刚度计算

依照材料力学原理,推导出了橡胶轴箱定位器的垂向,横向和纵向刚度计算公式,推导中考虑了形状函数和压缩对三向刚度的影响,用此公式所得的计算值与实测值基本相近。另外,还通过计算值考察了空穴角对三向刚度大小及变化关系的影响规律。     

预压量对橡胶球铰综合性能的影响

用实验与分析相结合的方法，对圆筒型橡胶球铰预压量与产品各向刚度的关系进行了对比研究，并分析了预压量对产品疲劳寿命的影响。结果表明，适量的周向预压量既能有效满足球铰各向刚度的匹配关系．又能显著提高球铰的疲劳性能，是产品设计的关键要素。     

轨道车辆用橡胶球铰结构快速设计模板的研究

以橡胶球铰几何参数、胶料硬度和球铰预压缩量为设计变量,以球铰刚度为目标函数并基于实验设计方法对整个设计空间进行了采样;根据所采样本的数据库建立了橡胶球铰几何参数-球铰刚度神经网络近似模型;基于该模型并借助Isight软件,编制了橡胶球铰结构快速设计模板;使用该模板可进行球铰刚度快速匹配和结构优化设计。以某型齿轮箱吊杆用橡胶球铰为例,验证了该模板计算精度的可行性。结果表明,使用该模板可大幅缩短橡胶球铰的开发时间并提高其疲劳性能和使用寿命,该模板计算精度的可行性较好,达到工程应用标准。     

橡胶球铰应力作用下的刚度变化研究

通过测试预压缩、多次刚度试验后的橡胶物理性能、动态机械性能和核磁共振交联密度等,分析了橡胶球铰在不同应力作用下的刚度变化。结果表明,应力作用可使橡胶球铰的刚度下降。预压缩过程中的剪切力可使橡胶分子链发生滑移,并有部分分子链发生断裂。在刚度测试过程中主要发生了交联网络内部重排现象,但没有分子链断裂现象发生。炭黑聚集体的破碎效应也是导致球铰产品刚度下降的因素之一。     

铁道混凝土枕轨下用50-10-9型橡胶垫板静刚度的初步探讨

研究了橡胶垫板静刚度的影响因素,做了不同配方的橡胶垫板的静刚度试验,研究结果表明:模具沟槽结构的不一致性是垫板静刚度不完全一致的原因之一;微晶蜡与si-1对橡胶垫板静刚度的影响不同,微晶蜡在一定程度上降低垫板的静刚度,而Si-1偶联剂对垫板的静刚度有利。     

金属-橡胶球铰扭转刚度试验研究

针对金属-橡胶球铰扭转刚度试验,分析了2种金属-橡胶球铰的结构与工作原理,设计了球铰水平纯扭转、垂直压缩扭转、组合扭转、系统扭转和组对扭转5种试验方案,并进行了分析对比;研究了不同径向预载荷、扭转速度和扭转方式对球铰扭转刚度的影响。结果表明,试验设计与实际工况一致;水平纯扭转和垂直压缩扭转2种试验方式均适用刚度试验;当增加径向预载荷或增大扭转速度时,球铰扭转刚度变大,单边加载扭转刚度大于正反加载扭转刚度。     

轨道车辆联轴器减振橡胶块试验设计及应用

针对轨道车辆联轴器减振橡胶块压缩性能和疲劳性能，分析了联轴器及减振橡胶块结构与原理，设计新型的导轨式压缩和疲劳性能试验方案，与剪切式方案进行分析对比，并应用新型方案进行了夹紧力、压缩刚度和组对疲劳试验。结果表明，新型试验结构设计合理，满足减振橡胶块夹紧力、垂向刚度和组对疲劳试验要求，且能准确模拟实际应用工况，所测试的夹紧力满足要求且随着疲劳次数增加而变大。     

模腔压力监测技术

模腔压力测量及监测技术已经有40多年历史,非常成熟,在欧美、日本等发达国家得到广泛应用。模腔压力测量数据可以用来进行注塑机开发与性能测试、模具结构设计与改进,以提高注塑制品质量及研究注塑     

Cavity balance for plastic injection molding

Cavity balancing is the process of altering the flow front within a cavity through thickness and design changes such that a desired fill pattern is achieved. This paper reports the preliminary research undertaken in developing an automated method for cavity balancing of two‐dimensional cavities. The aim of the automated cavity balancing routine is to reduce product development time and to improve product quality. This will lower the level of prerequisite expert knowledge necessary for successful mold and part design. The automated cavity balancing routine has been developed using the concept of flow paths. The hill‐climbing algorithm was employed on the cavity fill pattern for generation of the flow paths. Replacing the flow paths generated using the straight flow path assumption in previous work, this method was found to be more versatile and suitable to automation. No special considerations or routines were required to overcome the presence of inserts within the cavity. The method has been implemented in a computer program running as an external loop to the Moldflow software. The models analyzed demonstrate that the proposed method is viable and robust.     

Cavity field for axially symmetric dielectrics

A useful parameter for characterizing drawn polymers is the anisotropy, v, in the average molecular polarizability, α. We examine, for an axially symmetric dielectric, the relation of v to the experimentally measurable anisotropy, u, in the permittivity, ?. The relatively simple limit of negligible electronic polarizability is studied explicitly and the resulting mathematical problem of finding the cavity field in an axially symmetric dielectric is solved to second order in the anisotropy, u. Our result is compared to the ad hoc modifications of the isotropic Onsager equation previously used in the literature and it is found that these formulae give anisotropies that may be in error by up to 10%. This amounts to a few degrees in the equivalent angle for the orientation function.     

内凹模具内腔加工方法的探讨

内凹模具,就是型腔的内部尺寸大于型腔边缘尺寸的模具。本文以内凹模具的加工为例,介绍了参数化程序在模具型腔铣削中的应用,提出了使用单刃螺纹铣刀,由参数化程序中某参数变量的规律变化驱动程序相应值的改变,从而获得满足实际加工需要轮廓轨迹的一种内凹模具内腔加工方法,在实际应用中达到加工精度要求。     

Energy Variations in Diffusive Cavity Growth

The assignment of boundary values for the chemical potential and the calculation of energy-release rates for the growth of creep cavities along grain boundaries by self-diffusion are discussed. For simplicity, it is assumed that the boundaries are flat and that surface and grain-boundary diffusion are the dominant transport mechanisms. As matter diffuses from the void surface into and along the grain boundary, misfit residual stresses are induced to alleviate the high stress concentration ahead of the cavity apex. As a result, the contribution of strain-energy terms to the chemical potential can be neglected in typical cases. Also, contrary to the Griffith crack-extension model, the energy dissipation incurred by diffusive removal of material from the cavity surface and deposition in the grain boundary is a major term in the energy transfers associated with cavity growth. The primary energy "sink" in diffusive cavity growth is shown to arise from the work done by the grain-boundary normal stress when matter is inserted in the near-tip region by diffusion, not from the loss of strain energy of matter that is removed from the cavity at its tip or from the work of bond separation. Thermodynamic restrictions on the angle formed by the void surfaces at their apex, where they join the grain boundary, are considered. Boundary values for the chemical potential are derived in a manner appropriate for arbitrarily large but elastic distortions of material near the cavity tip and, in contrast to most previous work in the area, the effects of surface tension (i.e. of "surface stress," as distinct from surface energy) are included.     

采用型腔压力控制转压点

介绍注射成型过程中采用型腔压力作为转压信号的转压方式控制转压点对注射成型制件质量的影响.并且通过实验与传统的注射时间、螺杆位置的转压方式进行比较,结果显示:采用型腔压力控制比其它转压方式得到的制件质量重复误差相对较低.     

塑料注射模模腔尺寸的计算

本文从实际生产中出现的两种极端状态出发推导了模腔尺寸计算的新公式，给出了塑件尺寸公差与塑件名义尺寸，收缩率波动范围，模具制造误差定量关系式，并以此为依据提出了判断塑件及成型尺寸精度的准则、提出了将塑件产量与模具尺寸计算相结合的模具设计思想。     

离心泵的空泡与汽蚀损伤

水泵广泛应用于工农业、国防及人们的日常生活中．但是汽蚀问题严重危害着水泵系统的安全运行。而汽蚀对材料的损伤机理至今还未完全弄清。本文利用涂漆法对离心泵开式叶轮进行汽蚀损伤试验，利用闪频仪观察叶轮内空泡的分布情况和形态，弄清了不同流量的3％扬程下降点状态下叶轮内发生汽蚀损伤的部位和引起损伤的空泡形态特征。另外对叶轮的叶片外端间隙和平衡孔对空泡形态和汽蚀损伤的影响进行了观察。     

Cavity formation on elongation in filled elastomers

Experiments were conducted on samples of crosslinked rubbers filled with poly(tetrafluoroethylene) powder or small glass beads. Volume changes on elongation were measured in a dilatometer. Slow deformation cycles showed considerable hysteresis, the volume on elongation being smaller than on contraction. There is much less hysteresis if the sample is degassed before the experiment. These observations suggest that, to a large extent, the volume of the cavities is determined by the availability of gases dissolved in the elastomer matrix. When the samples were saturated with carbon dioxide, nitrogen, and helium, it was indeed found that the degree of cavitation increased in order with the solubility of these gases. The initial rate of cavitation is high. After about 1 min, dilatation is proportional to the logarithm of time. This rate is inversely related to the solubility of the gas present. When a sample is subjected to a constant tensile stress under vacuum and the external pressure is suddenly brought to atmospheric, the elongation at first decreases due to compression of the cavities and then increases slowly as gas diffuses into them. Even unfilled compounds mixed mechanically contain submicroscopic holes. These enlarge on deformation thus causing dilatation. Only for samples prepared by evaporation from solution is there no pressure dependence of the apparent modulus. It is demonstrated that the relation between the volume of vacuum cavities and the external pressure resembles that of volume and inflation pressure of a spherical hole in an infinite elastic medium.