基于粗糙齿面的齿轮传动混合弹流润滑研究

发布时间：2018-01-23 19:11

本文关键词： W-M分形函数弹流润滑粗糙齿面重载齿轮传动　出处：《太原理工大学》2012年硕士论文　论文类型：学位论文

【摘要】：现行齿轮传动接触疲劳强度设计基于仅仅适用于光滑表面干接触的赫兹(Hertz)理论。然而,绝大部分齿轮传动都处于混合润滑状态,即在两接触齿面之间既存在着将其分开的润滑油膜又存在着直接碰撞的粗糙峰,这显然与Hertz理论有很大的区别。因此,对齿轮传动进行混合弹流润滑研究既完全必要又有很强的理论意义。在探讨齿轮传动混合弹流润滑时,研究人员往往在齿面上人为设定一个或多个粗糙峰或用正(余)弦函数表征齿面粗糙度分布,这无疑与齿面粗糙纹理真实形状有较大差距。本文采用W-M分形函数模拟齿面粗糙纹理,以生成粗糙度函数并将其叠加到油膜厚度方程中；然后,采用多重网格法计算压力分布、采用多重网格积分法和逐列扫描法分别计算油膜厚度和温度分布；接着,以某矿用重载齿轮传动为例,数值计算了沿啮合线5个特殊点处的齿面压力分布、油膜厚度及轮齿接触区次表面的应力分布。此外,本文还通过多组数值计算,从理论上分别探讨了齿面粗糙度和润滑剂粘度对轮齿接触应力和齿面油膜厚度的影响,并通过回归分析,获得了彼此之间的定量关系。总结本文研究成果,可得如下研究结论： (1)在计入齿面粗糙度效应后,齿面压力分布及接触区次表面应力分布与Hertz分布差异显著。因此,现行以Hertz理论为基础设计齿轮传动接触疲劳强度的做法有待完善。 (2)啮入点是齿轮传动啮合线上的危险点,因为该处的油膜厚度最小且接触应力最大。因此,以节点参数为依据进行齿轮传动接触疲劳强度设计的做法值得商榷。 (3)随着齿面粗糙度的增加,平均油膜厚度几乎呈线性增加,而接触区次表面主剪应力的最大值则是先逐渐降低然后再不断变大,即二者之间呈抛物线关系。因此,当齿面光洁度达到一定值后,再一味提高齿面加工质量并不能达到延长齿轮传动疲劳寿命之目的。 (4)齿面粗糙度会使压力分布与油膜厚度产生锯齿形波动,且润滑剂粘度愈低,波动愈剧烈。在其它参数固定不变的情况下,随着润滑剂粘度的增加,齿轮传动润滑状态从边界润滑历经混合润滑逐渐过渡到全膜润滑。因此,在一定的工矿条件下,提高润滑剂粘度可有效降低齿面接触应力,从而提高齿轮传动接触疲劳寿命。
[Abstract]:The current design of contact fatigue strength of gear transmission is based on Hertz Hertzian theory, which is only suitable for dry contact of smooth surface. However, most gear drives are in mixed lubrication state. That is to say, there is a rough peak between the two contact tooth surfaces that separate the lubricant film and collide directly, which is obviously different from the Hertz theory. It is necessary and theoretical to study the hybrid elastohydrodynamic lubrication of gear transmission. When discussing the hybrid elastohydrodynamic lubrication of gear transmission, researchers often set one or more rough peaks on the tooth surface or use the sine (cosine) function to characterize the roughness distribution of the tooth surface. In this paper, W-M fractal function is used to simulate the rough texture of tooth surface to generate roughness function and superposition it into the oil film thickness equation. Then, the pressure distribution is calculated by multi-grid method, and the oil film thickness and temperature distribution are calculated by multi-grid integration method and row by row scanning method respectively. Then, taking a mine heavy-duty gear drive as an example, the distribution of tooth surface pressure, oil film thickness and the stress distribution in the contact area of gear teeth along five special points of the meshing line are numerically calculated. The effects of tooth surface roughness and lubricant viscosity on contact stress and oil film thickness of tooth surface are discussed theoretically by multi-group numerical calculation, and regression analysis is carried out. The quantitative relationship between each other is obtained. After summarizing the research results of this paper, the following conclusions can be obtained: 1) after the tooth roughness effect is taken into account, the distribution of tooth surface pressure and sub-surface stress in contact area is significantly different from that of Hertz distribution. The method of designing contact fatigue strength of gear transmission based on Hertz theory needs to be improved. Erosion-in point is the dangerous point on the meshing line of gear transmission because the oil film thickness is the minimum and the contact stress is the largest. The design of contact fatigue strength of gear transmission based on joint parameters is debatable. 3) with the increase of tooth surface roughness, the average oil film thickness almost linearly increases, while the maximum of the main shear stress on the subsurface of the contact area decreases gradually and then becomes larger. That is, the relationship between them is parabola. Therefore, when the finish of tooth surface reaches a certain value, it is not possible to prolong the fatigue life of gear transmission by blindly improving the machining quality of tooth surface. The roughness of tooth surface will cause sawtooth shape fluctuation between pressure distribution and oil film thickness, and the lower the lubricant viscosity, the more violent the fluctuation. When other parameters are fixed, the viscosity of lubricant increases with the increase of lubricant viscosity. The lubrication state of gear transmission is gradually transferred from boundary lubrication through mixed lubrication to full film lubrication. Therefore, under certain industrial and mineral conditions, increasing the viscosity of lubricant can effectively reduce the contact stress of tooth surface. Thus, the contact fatigue life of gear transmission is improved.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH132.41

【相似文献】