| Researchers often focus on raising the loading capacity of gear surface. Thus this paper, integrating mesh theory and in-situ trbochemical treatmeant, studies a new method---conducting the following research work by the technique of on-line strengthing the components' surface.To make it simpler, a pair of spur gear is chosen to be carefully analyzed on its surface conjugate meshing by means of mesh theory, then a model of equivalent movement is built up. Next, the film thickness between the gears is calculated by using Elasto-Hydrodynamic, and its lubricating state is evaluated by using film parameter. Finally, the gear pair loading capacity is worked out based on 《GB3480-83 Methods for the calculation of load capacity of involute cylindrical gears》.Using inorganic borate as the anti-friction addictive, based on 《GB11144-89 Lubricating fluids—Measurement of extremeprssure properties—Timken method》, we get the OK value of three groups of lubrication oil, among which, No.3 oil, that is, ISOVG68 mineral lubricant+5%Na2B4O7+2%RE nanometer powder+ 1%BOA + 1% T154 is the highest, 222.4N.Self-designed and built gear rig with opened power circulation, No.3 oil is chosen as the lubrication oil for the experiment, an comparative experiment is made with ISOVG68 mineral lubricant as the lubrication oil. The result is: when ISOVG68 mineral lubricant used as the lubrication oil, put in 3000rpm,5.96Nm, the pitch line of the gear surface is found extensively pitting and the gear surface plastically deformed. When No.3 oil is used, put in 3000rpm,8.59Nm, the gear surface has an obvious plastic flow, an obvious groove is found on pitch line of the driving gear (the smaller one), an obvious edge is found on pitch line of the driven gear (the bigger one). The operating surfaces of both driving gear and the driven one is high in smooth finish, no pitting.Through the analysis on the gear surface (only based on the gear in experiment with No.3 oil), it is found that: boron on the gear surface permeates the surface in the process of conjugate meshing and forms the modifying layers totally different from its basic structure and function. The roughness of the gear surface reduces which is caused by much fewer tiny asperity on the gear surface due to running-in. In addition, microhardness of the gear surface has raised due to joint function of processing hardness since the boron on the gear surface permeating the surface forms modifying layers and plastic flow. Through this experiment some problems in the evaluation system of the traditional gear lubricating state and surface damage are pointed out, that is, the first, based on EHL the film thickness between the gears is calculated, the second, the film parameter is calculated, finally its lubricating state is evaluated by using film parameter and thus the surface damage of the gear is worked out. In the above it is ignored that in the state of boundary lubricating, the active atom resolved from the additive permeates the surface and forms the modifying layer totally different from its basic structure, elements and function and thus greatly raises the anti-fatigue strength. The drawback with GB3480-83 Methods for the calculation of load capacity of involute cylindrical gears equivalent to ISO/DP6336/I∽III-1980 is also pointed out: when taking into account lubricating state of gear surface influence on loading capacity of gear surface, In the above it is study on based EHL , and is ignored that in the state of boundary lubricating, as well as favorableness conditions in gear surface conjugate meshing, the active atom resolved from the additive permeates the surface and forms the modifying layer totally different from its basic structure, elements and function and thus greatly raises the loading capacity of gear surface . Idea and design rule of additive correcting coefficient , for correcting lubricant coefficient , is put forward. i.e. additive correcting coefficient mainly is related with load drove by gear pair, rotate speed, center distance, material for... |
PDF Full Text Request