润滑剂粘度及齿轮转速对轮齿接触应力的综合影响

发布时间：2018-01-05 16:02

本文关键词：润滑剂粘度及齿轮转速对轮齿接触应力的综合影响　出处：《太原理工大学》2013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的设计基础是Hertz理论,而Hertz理论仅仅适用一对光滑表面之间的静态干接触,这与齿轮传动的实际工况有较大差异,因为齿轮传动大多在润滑状态下运转。为了弥补这一差异,渐开线圆柱齿轮承载能力计算的国际标准(ISO/6336：1996)以及相应的国家标准(GB3840-1997)中分别推荐了润滑系数和速度系数,一些学者也分别探讨了润滑剂粘度和齿轮转速对齿轮传动接触应力的影响。然而,不难理解,润滑剂粘度数值的选择与齿轮转速无不相关。因此,有必要从理论上探讨二者对齿轮传动接触疲劳应力的综合影响。本文首先建立了渐开线圆柱齿轮传动的润滑模型；然后,基于热弹流润滑理论,采用多重网格法、多重网格积分法、逐列扫描法分别求解齿面压力分布、油膜厚度分布和温度分布；在此基础上应用弹性接触理论求解轮齿接触区次表面应力分布；最后,主要针对中、重载尤其是重载齿轮传动,分别从润滑剂粘度η0和齿面综合速度u之乘积η0U固定、定粘度变综合速度、定综合速度变粘度、粘度与综合速度均单调增大四种方式,共进行了588组数值计算。总结数值计算可得如下主要结论： 1.在润滑剂粘度和齿面综合速度之乘积η0U固定不变时,同时改变其中任一量,对齿轮传动接触疲劳应力不会产生影响。 2.当Hertz接触应力pH≥1.0GPa时,无论润滑剂粘度如何变化,轮齿接触区次表面主剪应力最大值τmax均小于Hertz接触的相应值；尤其当PH≥1.3GPa时,τmax随着η0U的增大单调减小,这也从理论上揭示了润滑对降低轮齿接触应力的有利作用。有必要特别指出的是,对于Hertz接触应力pH1.3GPa的载荷工况,当齿轮转速固定时,τmax与润滑剂粘度η0之间呈抛物线关系,即当粘度大于一定值后,轮齿接触应力随着粘度的增大不降反增,这一理论结果已被前人的试验结论验证。然而,如上所述的国际标准(ISO/6336：1996)以及相应的国家标准(GB3840-1997)中所给出的润滑系数均随润滑剂粘度的增大单调增大。因此,有理由认为,该润滑系数一般只适用于重载齿轮传动。 3.主剪应力的最大值τmax的X坐标值随着η0U的增大逐渐向出口区移动；而ττmax的Z坐标位置不随乘积η0u的增大而改变,基本恒定在0.8处。 4.第二压力峰Pmax之值随着η0U的增大波动性增大;载荷越大,增大的幅度就越小；Pmax的位置即牙坐标值随着η0U的增大在减小,即逐渐向入口区移动。 5.应用多元回归理论,建立了重载工况条件下轮齿接触区次表面主剪应力最大值τmax与乘积η0U之间的回归方程。基于此方程,可以在设计重载齿轮传动时定量考虑润滑剂粘度和齿轮转速的综合影响。这对完善齿轮传动接触疲劳强度设计理论、提高设计结果可靠性具有积极意义。本文不足之处是数值计算限于全膜润滑状况下进行,未能考虑由于齿面粗糙度效应所引起的时变性。
[Abstract]:The basic design of the contact fatigue strength of gear transmission is the current Hertz theory, Hertz theory is applicable only to a static smooth surface between the dry contact conditions and the gear transmission are quite different, because most of running gear transmission under lubricating condition. In order to compensate for this difference, calculating the bearing capacity of the international standard of involute cylindrical gear (ISO/6336:1996) and the corresponding national standards (GB3840-1997) are recommended lubrication coefficient and velocity coefficient, some scholars also discussed the influence of gear lubricant viscosity and rotational speed on the gear contact stress. However, it is not difficult to understand, the lubricant viscosity numerical selection and gear speed are related. Therefore, it is necessary to study the comprehensive effect of the two contact fatigue stress of gear transmission in theory.
This paper firstly established the lubrication model of involute cylindrical gear transmission; then, based on the thermal elastohydrodynamic lubrication theory, the multigrid method, multigrid integral method, the column scanning method respectively for tooth surface pressure distribution, oil film thickness and temperature distribution; on the basis of using elastic contact theory to solve the tooth contact surface should be the stress distribution; finally, mainly for heavy load, especially heavy load gear lubricant viscosity and 0 respectively from the tooth surface integrated velocity u 0U product fixed, fixed viscosity variable speed, constant speed integrated variable viscosity, viscosity and velocity are increasing in four ways, a total of 588 groups of numerical calculations summary of numerical calculation. We can get the following main conclusions:
1. in the product integrated speed of lubricant viscosity and tooth surface of 0U fixed, and change any amount of force will not influence on the contact fatigue of gear transmission.
2. when the contact stress is pH = 1.0GPa Hertz, regardless of how to change the lubricant viscosity, tooth contact surface the maximum principal shear value corresponding to Max were less than Hertz contact stress; especially when PH is larger than 1.3GPa, Max decreased with increased 0U, it also revealed the lubrication to reduce the beneficial effects of tooth contact stress is necessary. In particular, for the Hertz contact load force pH1.3GPa, when the gear speed is fixed, Max and lubricant viscosity showed a parabola relationship between the 0, when the viscosity is greater than a certain value, the tooth contact stress with the increase of viscosity does not fall by this theory, experimental results have been verified previous conclusions. However, as mentioned above, the international standard (ISO/6336:1996) and the corresponding national standard (GB3840-1997) in the lubrication coefficient increase with the increase of the lubricant viscosity monotonously, It is reasonable to think that the lubrication coefficient is generally applicable only to heavy load gear transmission.
3. the maximum principal shear X coordinate values with the increase of Max tau ETA 0U moves to outlet zone stress; and change the Z position of Max does not increase with the tau tau ETA 0U product, basically constant at 0.8.
4. second Pmax with the increase of pressure peak value of ETA 0U increased volatility; the larger the load is, the rate of increase is smaller; the Pmax is the position of the teeth coordinate 0U increases with ETA decreases, which gradually moved to the entrance area.
5. application of multivariate regression theory, a heavy load tooth contact surface the maximum principal shear stress regression equation between the max and the product of tau ETA 0U. Based on this equation, can be in the design of gear transmission when considering quantitative effects of lubricant viscosity and gear speed. This will improve the gear contact fatigue strength the design theory is of positive significance to improve the reliability of the design.
The shortcoming of this paper is that the numerical calculation is limited to full film lubrication, and the time variability caused by the tooth roughness effect is not considered.

【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TH132.41

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