| With the national and social requirements for energy saving,emission reduction and high performance of internal combustion engines,the working conditions faced by the cylinder liner and piston ring friction pair in internal combustion engines are becoming more and more severe,and the wear of the piston ring and cylinder liner system has become a key factor in determining the life of internal combustion engines.Micro pit texture processing on the surface of friction pair has become the most effective means of lubrication and wear reduction.However,due to the limitation of processing methods,the micro pit morphology of cylinder liner piston ring is mainly circular micro pit,and the research on special-shaped micro pit,especially elliptical micro pit,is less.In the simulation study,elliptical micro pit has better lubrication and wear reduction performance than circular micro pit.The laser processing technology and friction and wear properties of elliptical micro pits were studied.1.The mechanism of pit texture in laser processing is described.In the process applicability experiment,it is found that the laser texturing process can form micro pits on the surface of typical metal materials.Although the depth of micro pits on the surface of different metal materials is different,the overall profile and geometric characteristics also have good regularity,which proves that the micro pit texture technology of laser processing has good process stability and material applicability.2.The influence law of laser processing micro-pit weaving process is investigated,and the results show that the ring filling process can obtain better micro-pit morphology than the other three filling processes.The maximum depth and area of the long diameter section of the micro pit increase with the decrease of the filling line width,and the maximum depth reaches218 μm.When the filling line width is small,the depth and area first increase and then decrease with the increase of scanning speed,and the inflection point is 400 mm / s.When the filling line width is large,the depth and area of the micro pit are inversely proportional to the scanning speed.The influence of laser frequency on depth and area is limited,and the maximum area change rate is only 5.61%.The main function is that with the increase of frequency,the bottom of the micro pit tends to be more flat.3.From the point of view of driven pressure lubrication,the lubrication model of micro pit array on the surface of friction pair is established by 3D CFD simulation,and the influence of micro pit geometric parameters on lubrication performance is explored.The simulation results show that the values of the parameters of the micro pits are as follows: When the inclination angle of ellipse is 0°,the depth of micro pit is 15 μm,and the area occupancy is13%,the average oil film pressure is the largest,which can effectively improve the oil film bearing capacity.It is found that the larger the initial velocity is,the stronger the oil film bearing capacity is.4.From the point of view of lean oil lubrication,the experimental scheme of friction and wear is designed,and the influence of micro pit array with different density and depth on the wear performance of friction pair is studied.It is found that the wear resistance of any sample with micro pit array texture is better than that of the sample without micro texture.The micro pit texture with 13% area shows better wear resistance.The micro pit depth has little effect on the wear resistance of lean oil lubrication. |
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