Research On Friction Properties Of Micro-textured Tooth Surface Based On Laser Technology

The surface micro-texture has the advantages of improving surface friction and wear performance,increasing surface bearing capacity and "secondary lubrication".It has been actually applied to the conformal contact fields such as piston rings-bushings,sliding bearings,and mechanical seals,and has achieved theoretical support and good results.At present,the research on micro-textured surfaces is gradually developing from conformal contact to non-conformal contact.For example,in the gear transmission process,the contact form of the friction pair is line contact,and it is also required to be able to transmit power.Therefore,the theoretical and experimental researches on the surface micro-texture in non-conformal contact are more demanding.The micro-dimple texture is applied to the rack transmission table as the object of study in this paper,and a simplified model of the gear meshing process is established.From the three aspects of theoretical analysis and simulation calculation,laser processing technology exploration and friction test verification,relevant theoretical and experimental researches on the combination of surface micro-texture and line contact friction pair were carried out.By exploring the application of micro-texture surface optimize tribological performance of rack transmission.The main research contents of the paper are as follows:(1)Theoretical study of micro-texture tooth surface lubrication.Based on the computational fluid dynamics(CFD)method of the N-S equation,a two-dimensional geometric model of tooth surface texture lubrication is established,and the oil film bearing capacity of the textured surface under different surface density,depth-to-diameter ratio,sliding speed and frictional heat conditions is analyzed and studied Influencing laws of various factors,and obtaining optimized texture design parameters.The results show that the surface density of the micro-dimples with the best dynamic pressure performance is between 20%and 50%;the depth-to-diameter ratio is 0.0375 to 0.075;as the sliding speed increases,the bearing capacity of the oil film continues to increase;as the frictional heat increases,the bearing capacity of the oil film increases first and then decreases.(2)Research on laser processing technology of micro-textured surface.Using picosecond laser to micro-texture laser processing 40Cr metal surface,focusing on the study of the influence of laser power,laser scanning speed,laser scanning times and the hatch distance on the micro-texture topography.Combined with three-dimensional surface profiler for surface inspection,explore optimized laser processing parameters.The results show that the optimal laser process parameters are respectively:at a laser power of about 5.72W and a scan speed of about 100mm/s,the texture depth can be increased by increasing the number of scans;the laser ring filling interval can be 0.004mm?0.008mm.(3)Study on tribological properties of micro-textured tooth surface.Based on the picosecond laser process,the micro-texture of circular dimples was prepared,and the ring-block line contact friction and wear experiment was carried out.The friction coefficient and wear morphology of micro-textured surfaces with different areal density,depth-to-diameter ratio and different loads and sliding speeds were studied.The results show that when the load is 50N and the sliding speed is 1.026m/s,the optimal area density is about 20%,and the optimal depth-diameter ratio is about 0.15;the load and friction coefficient have an inversely proportional linear relationship;the sliding speed and friction coefficient have a proportionally linear relationship;the worn surfaces have different degrees of Oxidative wear,adhesive wear and abrasive wear..