【作者】 武斌；

【导师】 石万凯；

【作者基本信息】 重庆大学 ， 机械设计及理论， 2010， 硕士

【摘要】 齿轮传动是机械传动中最重要且应用最广泛的传动形式之一,它的接触强度设计是以hertz弹性接触理论为基础,而这种理论只是光滑表面且无润滑的静态接触,这与实际有很大的差距。然而在齿轮润滑过程中,弹流油膜的厚度通常只有1μm左右甚至更小,而齿面因切削形成的粗糙度和它处于一个数量级,齿面粗糙峰频繁碰撞,造成接触峰点弹塑性变形和金属迁移。大量实验证明,齿面损伤都是因润滑失效引起的,如点蚀、过度磨损以及胶合等,尤其在低速重载齿轮传动中润滑失效占失效的60%以上。因此,对低速重载齿轮传动热弹润滑研究具有较高的理论意义和实际价值,本文具体的研究工作及结论如下:1)首先在齿轮啮合原理、齿面粗糙度效应和非牛顿流体特性的基础上建立了低速重载齿轮传动微观热弹流润滑的数学模型,并针对该数学模型中形式相当复杂的二阶非线性偏微分方程组的特征,运用多重网格法(Multi-Grid Method)求解压力分布时变解、多重网格积分法计算弹性变形、逐列扫描法计算温度分布时变解,并分析了影响低速弹流润滑的几个主要因素,结果表明,在一定的条件下,粗糙度越大,产生的局部压力峰越大,而油膜厚度也相应减小,同时最大温升也有一定程度增加;随着速度的增加,油膜厚度有所增加,油膜平行部分相应缩短,二次压力峰的位置逐渐向入口区方向移动,最大的油膜压力也逐渐降低;润滑油粘度的影响主要体现在油膜形状上,润滑油粘度越高,形成的油膜厚度越大,同时油膜间产生的剪切热也越强烈;当载荷越大时,压力分布逐渐接近于Hertz接触压力分布,而载荷越小时,压力分布和经典润滑理论计算的结果非常相似。2)参照风电增速箱低速级的行星轮传动的参数和受载情况,建立了相应数学模型,得到太阳轮与行星轮、行星轮与齿圈的热弹流润滑完全数值解,分析油膜压力和膜厚形状与损伤和磨损的关系。结果表明齿圈和行星轮在Ra=0.8μm时,油膜比厚小于1.5,处于不正常工作状态,它的齿面损伤度可达10%以上。3)采用在氧化磷化条件下齿轮跑合方案,分析了齿轮在磷化中的化学反应机理:浸入的磷化液使齿轮表面形成结晶型磷酸盐转换膜软化层,在齿轮啮合时产生的摩擦力作用下使齿面粗糙度逐渐降低。通过对比了处理后齿轮和未处理的齿轮在二种不同方案下润滑油温升变化情况,结果表明,降低粗糙度对齿轮啮合时润滑油温度有明显的改善效果。更多还原

【Abstract】 Gear transmission is the most important and most widely used form of transmission. In common, there is great different for contact strength design of gears based on Hertz elastic contact theory, which is just used for static contact as so smooth surface with no lubrication. However, in the process of gear lubrication, elastohydrodynamic oil film thickness is about 1μm or smaller, which is almost in the same order of magnitude with tooth surface roughness formed by cutting. Under this condition, it is an frequency of tooth surface asperity collisions, which is leaded to plastic deformation and metal migration. A large number of experiments show that tooth surface damage is caused by lubrication failure, such as pitting, excessive wear and glue, etc., especially in low speed heavy gear failure in the lubrication failure accounted for more than 60%. Therefore, there is higher theoretical and practical value for low-speed heavy gear lubrication of thermoelastic. These detailed studies are as follows:1) First of all, the mathematical model for micro-thermal elastohydrodynamic lubrication based on gear engagement theory, surface roughness effect and the non-Newtonian behavior is set up. Owe to complexity of second-order nonlinear characteristics of partial differential equations, Some challenging numerical calculation methods are adopted such as multi-grid method (Multi-Grid Method) to solve the pressure distribution of time-varying solution, multiple grid integration method to elastic deformation and the column scanning method to temperature distribution and then several major factors impacting low-speed EHL are discussed. the results show that under certain conditions, the greater the roughness, the greater the resulting local pressure peaks, while the film thickness correspondingly decreases and the maximum temperature rise also increased to some extent; When speed is becoming geater, film thickness is increasing with the corresponding parallel part of the film shortening, the position of the second pressure peak gradually is shifting to the entrance area, and even the largest film pressure is gradually reduced; oil viscosity is mainly reflected in the film shape, The higher the oil viscosity, the greater the formation of film thickness, while oil film shear heat generated by the more strongly; when larger loads, the pressure distribution gradually close to the Hertz contact pressure distribution, while the load is smaller, the pressure distribution is similar with the result calculated by classical lubrication theory. 2) The reference to gear parameters and load conditions of a company’s wind power growth of low-level box planetary gear, a mathematical model is established to solve gear complete thermal EHL numerical solutions for sun gear, planetary gear and ring and then the relationship between film pressure and film thickness of planetary gear system and damage and wear is analyzied. The results show that the ring gear and planet gear with Ra = 0.8μm work in abnormal state, whose degree of tooth injury up to 10% on account of the oil film thickness less than 1.5.3) The papar proposed gear running programs under the oxidation and phosphate conditions, and analyzed chemical reaction of the gears in phosphate solution: gear in reaction with solution is formed on the surface softening membrane of crystalline phosphate conversion layer, which is wiped by friction when gear is meshing. Over and over again roughness peak of gear tooth surface is decreased. Then by comparing the treated and untreated gears in the two kinds of programs, oil temperature of gear with lower roughness is great lower than anothers.更多还原