共查询到17条相似文献,搜索用时 672 毫秒
1.
多点接触乏油弹流润滑模型及试验研究 总被引:1,自引:0,他引:1
为探讨多点接触乏油弹流润滑机制,基于球与滚道接触区域的排油和补油平衡,建立适用于不同润滑状态的油膜厚度计算模型,可以计算从充分供油、乏油到干涸乏油的中心膜厚以及油膜不平衡时中心膜厚随滚动次数的衰减。利用自制的球-盘接触光干涉弹流试验装置,通过安装双镜筒同时获取相邻球的油膜图像,研究多点接触中相邻球的轨道重合和不重合时前球尾迹对后球油膜图像和中心膜厚的影响。结果表明:乏油润滑条件下,前后球的轨道不重合时轨道之间可相互补油;前后球的轨道重合时,在给定供油条件下,随着滚动线速度增加,入口弯液面逐渐靠近接触区域,中心油膜厚度增加,与相同工况下乏油润滑模型计算的膜厚对比吻合较好,验证了所建乏油润滑模型的正确性。 相似文献
2.
点接触弹流润滑供油条件退化的乏油分析 总被引:1,自引:0,他引:1
在点接触弹流润滑中,如果不能及时补充新油,则接触区的供油条件会随着润滑次数而退化。分析了供油油膜厚度、中心膜厚、最小膜厚和润滑油膜压力区形成位置与润滑次数的关系。结果表明:润滑开始时,由于供油油膜厚度较大,系统处于充分供油状态;随着润滑次数的增加,有一部分油从两侧泄漏,系统逐渐转到乏油状态,供油油膜厚度、中心膜厚和最小膜厚均逐渐变小,压力区形成位置则逐渐向Hertz接触区靠近;最终供油油膜厚度、中心膜厚和最小膜厚趋于定值,压力区趋于Hertz接触区,从而达到一种稳定乏油状态。 相似文献
3.
4.
为研究乏油条件下偏心凸轮副的润滑状态,基于凸轮-挺杆机构建立时变乏油润滑模型,探究一个周期内6个典型瞬时(60°、120°、180°、240°、300°、360°)的压力和油膜厚度变化规律,并分析不同凸轮旋转角度下转速、初始载荷和润滑油黏度等参数对接触区润滑状态的影响。结果表明:当凸轮转至180°时,膜厚最小,压力最大,乏油状况最严重;限量供油下最小膜厚出现在凸轮转角为180°时,但是凸轮转角为0°时乏油速度最快,乏油程度更深;增大凸轮旋转速度时乏油速度更快,乏油程度更深;相同供油条件下,润滑油黏度越高使得接触区乏油情况越严重,乏油速度更快,乏油程度更深;载荷对接触区的润滑状态的影响较小,只在凸轮转角为0°接触区卷吸速度最大时,能够体现出载荷对接触区润滑状态的影响。 相似文献
5.
点接触乏油混合润滑的数值模拟研究 总被引:1,自引:0,他引:1
基于改进的统一Reynolds方程,对点接触乏油混合润滑进行数值模拟,研究供油量、载荷、卷吸速度等对混合润滑性能的影响。分析时将润滑区域分为两部分,在压力区润滑油完全充满间隙,在空穴区润滑油部分充满间隙,这两区域的润滑特性都采用离散化的Reynolds方程求解;采用快速傅立叶变换算法求解弹性变形,采用GaussSeidal低松弛迭代逐行扫描法求解压力。结果表明:随着初始供油量的变化,润滑油油膜压力、油膜厚度以及部分油膜比例都会受到影响;速度对点接触乏油混合润滑的影响主要表现在油膜厚度分布上,而载荷的影响主要表现在压力分布上;随着载荷的升高,油膜压力将增大,而油膜厚度有轻微的减小,随着速度的升高润滑油油膜厚度减小。 相似文献
6.
7.
摆线针轮行星传动啮合过程中供油量变化影响传动效率和接触疲劳特性。引入部分油膜厚度比例,以入口油膜厚度来表征乏油程度,建立摆线针轮有限长线接触乏油润滑数值模型,研究在齿宽方向上入口油膜厚度不均匀分布对压力和膜厚分布的影响。结果表明:乏油条件下,随着入口供油量增加,入口油膜厚度的不均匀分布对齿宽方向上的压力和膜厚分布的影响减小;随着速度的增加,齿宽方向压力和膜厚分布受入口油膜厚度不均匀分布的影响增加;随着载荷的增加,齿宽方向压力和膜厚分布受入口油膜厚度不均匀分布的影响程度减小。 相似文献
8.
乏油条件下圆柱滚子轴承的弹流润滑分析 总被引:1,自引:0,他引:1
基于有限长线接触弹流润滑理论,将等效供油层厚度和轴承相关参数作为输入量,求得乏油条件下圆柱滚子轴承弹流润滑的完全数值解;比较充分供油与乏油条件下轴承的润滑性能,研究乏油条件下供油层厚度、载荷、转速对圆柱滚子轴承润滑性能的影响。结果表明:随着供油量的减小,油膜厚度减小,第二压力峰降低,压力的起始点位置移向Hertz接触区;载荷增加,油膜厚度减小,这将对轴承的润滑产生十分不利的影响;随着转速的增加,压力区变得平坦,油膜颈缩向出口区移动,乏油程度更加严重。 相似文献
9.
10.
11.
P. M. Cann 《摩擦学汇刊》2013,56(4):867-873
Many grease lubricated roller bearings operate in the starved elastohydrodynamic (EHL) regime where there is a limited supply of lubricant to the contact (1). Under these conditions the film thickness drops to a fraction of the fully flooded value (2) and, thus, it is difficult to predict lubrication performance, or bearing life, from conventional EHL models. In this regime film thickness depends on the ability of the grease to replenish the track rather than the usual EHL considerations. The conventional view of grease lubrication is that base oil bleeds from the bulk reservoir close to the track, replenishing the inlet and forming a fluid EHL film (3). Resupply, under starved conditions, will thus depend on both operating conditions and grease parameters. The aim of this paper is to evaluate the influence of these parameters on starved lubrication in a rolling contact. Starved film thickness has been measured for a series of greases and the results have been compared to the fully flooded values. These show that the degree of starvation increases with increasing rolling speed, base oil viscosity and thickener content but decreases at higher temperatures. In many cases an increase in absolute film thickness is obtained when moving from high viscosity base oil to a low one, this result is the reverse of normally accepted EHL rules. Taking the fully flooded film thickness as a guide to lubrication performance is therefore not valid as grease film thickness in the starved regime is determined by local replenishment rather than bulk rheological properties. 相似文献
12.
13.
针对核主泵、船用轴系等特定工况下推力轴承润滑油的进水问题,以46润滑油和68润滑油为例研究润滑油水侵对推力轴承润滑性能的影响。通过黏度测试获得润滑油中水分质量分数为0、0.5%、1.0%时的运动黏度,采用黏温曲线对润滑油含水前后的动力黏度进行表征。将润滑油的黏温关系代入推力轴承的润滑计算当中,获得不同含水量下轴承的最小油膜厚度、温升、流量及功耗等静态特性参数,并分析含水量对推力轴承起飞转速的影响。研究结果表明:润滑油含水后对最小油膜厚度和功耗影响较大,对温升和流量影响较小;随着润滑油含水量的增加最小油膜厚度和功耗均降低,而温升增大,流量减小;使用2种润滑油在不含水和水分质量分数为0.5%时的起飞转速都在50 r/min以下,水分质量分数为1.0%时起飞转速都在50 r/min以上,表明随着含水量的增加起飞转速增大。 相似文献
14.
15.
Improving knowledge on the film forming behavior of greases is essential to be able to develop efficient greases. This article examines how operating conditions (e.g., temperature, lubrication condition [fully flooded/starved]) and base oil viscosity influence the film forming properties of greases by comparing the behavior of two lithium-based greases and their respective base oils in rolling point contact. It is found that the onset and degree of starvation is controlled by speed (u) × viscosity (ν)/load (W) factor (uν/W) and temperature and that low uν/W values promote entrainment of thickener into contact. Thus, grease with low base oil viscosity shows significant thickener entrainment in the low speed region compared to the one with high base oil viscosity, which leads to the formation of thickener-rich viscous material during extended running with the low base oil viscosity grease. The results suggest that the shape of the film thickness versus speed curve is viscosity and uν/W range dependent. Furthermore, for the test conditions used in this study, grease-lubricated contacts appear to shift from the initial fully flooded condition to starved condition over a prolonged running of 2 h. The results from this study concur with those reported in the literature that fully flooded oil elastohydrodynamic lubrication (EHL) theory or film thickness cannot be directly applied or taken as a guideline in grease-lubricated contacts. 相似文献
16.
为了探究氧化石墨烯(GO)添加剂在不同润滑状态下对基础油成膜特性的影响,利用原子力显微镜(AFM)和傅里叶变换红外光谱仪(FTIR)分别对GO的厚度、层数和表面官能团进行表征,选用聚α-烯烃(PAO10)和聚醚(PAG)为基础油,利用球-盘点接触光干涉油膜厚度测量试验台,研究GO添加剂在弹流润滑和混合润滑状态下对不同基础油润滑成膜性能的影响。结果表明:在全膜润滑状态下,GO对PAO10和PAG基础油的成膜能力影响很小,添加GO前后基础油的最小膜厚相差并不大;在混合润滑状态下,GO可有效地提高PAO10基础油的最小膜厚,减缓接触区内的乏油状况,而对PAG基础油成膜性能的影响很小。 相似文献
17.
Lubricant starvation of the contact can occur in high-speed oil or grease lubricated bearings resulting in reduced elastohydrodynamic (EHL) film thickness (Lubricat. Sci. 11 (1999) 227). To achieve optimum bearing performance and component life, it is obviously desirable to be able to predict when starvation will occur and the resulting level of surface protection. For both oils and greases, the transition between fully flooded and starved behaviour is determined by lubricant loss and replenishment of the track (ASME Trans. J. Tribol. 120 (1998) 126; Cann PME, Chevalier F, Lubrecht AA. Track depletion and replenishment in a grease lubricated point contact: a quantitative analysis. Proceedings of the 23rd Leeds–Lyon Symposium on Tribology. 1996. p. 405–14). The current paper develops a criterion for the fully flooded and starved transition of an oil-lubricated contact based on four primary factors controlling lubrication level; these are volume of oil, contact dimensions, oil viscosity and speed. Experiments have been carried out using an optical EHL device to investigate the effect of each of these parameters on starvation. The results show how the boundary between the fully flooded and the starved regime and the film thickness in the starved regime depend on these parameters. A single dimensionless parameter (SD), based on replenishment local to the contact, has been established between the operating parameters and the transition from the fully flooded to starved regime.In this paper, the starvation criterion has been developed for an oil-lubricated contact with a fixed volume of oil present. The next stage is to extend the analysis to grease and the prediction of lubrication failure in bearings. 相似文献