Analytical And Experimantal Investigation On The Tribological Properties Of Friction Pairs With Micro-Grooves Surface Textures

Surface texturing is a new technology for improving the contact and lubrication state of friction pairs by processing certain patterns with defined sizes, shapes and arrays on frictional surfaces. It's been shown that the tribological performance of mechanical components can be significantly improved by choosing suitable geometrical parameters of surface texture. At present, most researches focus on the textures of micro-dimples, however, there are only few studies paying attention to the textures of micro-grooves, especially in lubrication theoretical research. For this reason, by solving the dimensionless Reynolds equation with the multi-grid method, investigations on the hydrodynamic pressure of fully or partially textured surfaces with regular linear grooves, fully textured surfaces with regular micro V-grooves were systematically studied.For fully textured surfaces with regular linear grooves, groove width, depth, spacing and orientation angle have significant effect on the load carrying capacity of the lubricating oil film. Optimum values of geometrical parameters such as groove depth, spacing and orientation angle can be found which correspond to maximum load carrying capacity. It is also noted that the load carrying capacity increases monotonically with increasing groove width. The results show that the hydrodynamic effect can be improved by employing optimized surface texturing design.For partially textured surfaces with regular linear grooves, groove depth, spacing and orientation angle have significant effect on the load carrying capacity of the lubricating oil film. However, groove width has little or no effect on the load carrying capacity. Optimum values of geometrical parameters such as groove depth, orientation angle and textured fraction can be found which correspond to maximum load carrying capacity. It is also noted that the load carrying capacity increases monotonically with increasing area density. The results of the study show that the hydrodynamic lubrication performance can be equivalent to a Rayleigh step slider by optimizing the partial surface texturing according to the operating parameters of the mechanical components.For fully textured surfaces with regular V-grooves, V-groove angle has significant effect on the load carrying capacity. Optimum values of geometrical parameters such as groove depth and transverse spacing can be found which correspond to maximum load carrying capacity. It is also noted that the load carrying capacity increases monotonically with increasing groove width and length, decreases with increasing longitudinal spacing.Based on the investigation of lubrication theories, experimental investigations of laser processing of micro-groove surface texture and tribological performance of V-grooves has been performed.Processing of the surface texture of micro grooves on 45* steel has been performed with a Q switched diode-pumped Nd:YAG laser. Effects of process parameters on the quality of micro-grooves have also been analyzed. It has shown that pumping current, repetition rate and scanning speed have significant effect on the geometrical parameters and quality of micro grooves.UMT-2 tribometer with a pin-on-disk friction pairs has been used to test the tribological performance of V-grooves. The result shows that the laser textured specimens with regular V-grooves exhibited lower friction coefficient than untextured specimens. Especially under the conditions of low loads and high speeds, the tribological performance can be improved greatly by V-grooves. It is basic anastomotic between the theoretical simulation and the experiment results. The causes of these differences have also been analyzed.The results obtained in the research diversify surface texture tribological theory, and provide a reference for the micro-groove design and its application.