Study On Anti-friction And Life-saving Technology Of Spherical Plain Bearing By Laser Composite Texturing

As an important part of modern mechanical equipment,spherical plain bearing is widely used in aviation equipment,rail transit,construction machinery,automobile manufacturing and other mechanical fields.As a kind of spherical sliding bearing,its characteristics include: simple mechanical structure,impact resistance,wear resistance,strong bearing capacity,self-aligning and so on.With the rapid development of modern industry,the demand for spherical plain bearing is increasing,higher requirements are put forward for the working performance and service life of spherical plain bearings.As an important joint of mechanical equipment,the friction and lubrication performance of the spherical surface of the spherical plain bearing is directly related to the normal operation of the whole equipment.Under heavy load,high speed,high temperature and other harsh working conditions,the traditional lubrication and wear reduction technology has been unable to meet the requirements of spherical plain bearing regular work.Starting from improving the tribological characteristics of the spherical plain bearing surface,the friction lubrication and wear characteristics of spherical plain bearings in different lubricating media were systematically investigated,by combining laser micro-texture technology,solid/liquid/grease lubrication technology and self-lubrication technology.In this paper,the laser processing method is firstly used to study the surface micro-texture structure on the surface of bearing steel GCr15 material,focusing on the impacts of laser single pulse energy,laser pulse repetition times and laser frequency on the shape and size(depth,diameter,etc.)of bearing steel surface dimple,the corresponding relationship between micro-molding processing parameters and micro-texture dimple morphology was summarized,and the better parameters of micro molding were selected to prepare for the later friction test.Secondly,the friction performance test of poly tetra fluoroethylene(PTFE)self-lubricating liner and micro-textured specimen surface under solid lubrication conditions was carried out to study the effect of different surface treatment,different solid lubricant,different density of micro-texture and micro-texture depth on the friction characteristics of sample surface,on this basis,the surface frictionproperties of the samples under different working conditions(load,reciprocating movement frequency)were also explored and analyzed.Finally,grease is used as the lubricating medium to compare the friction characteristics of the self-lubricating liner and the micro-textured surface under different surface treatment conditions,and the friction and lubrication properties of samples with different micro-texture densities was studied in oil/grease lubricated medium,in addition,the variation of the surface friction characteristics of the sample was studied by changing the test conditions.The conclusions are as follows.The results of laser process test show that: in the single pulse mode,the diameter parameters of micro-textured circular dimple on the surface of bearing steel are mainly affected by the laser single-pulse energy through using Nd:YAG laser,the larger the single-pulse energy is,the larger the diameter of the dimple is.The number of pulse repetitions has a significant effect on the micro-texture depth,the more repetition times,the deeper texture depth.With the increase of laser frequency,the micro-texture parameters increase,and then decrease.The results of solid lubrication test show that: compared with the single lubrication technology,the combination of PTFE,micro-texture and solid lubrication technology can effectively improve the lubrication performance of bearing steel sample surface.The lubricating effect of nano-level solid lubricant is better than that of micron lubricant.The micro-texture density becomes larger,and the friction coefficient on the surface of the sample decreases and then rises,when the texture density is 20%,the effect of lubrication is best.The friction coefficient decreases first and then increases with the increase of texture depth,and the friction performance is best at the depth of 9 um.With the increase of reciprocating frequency,the friction coefficient on the surface of the sample first decreases and then increases.The friction coefficient decreases with the increase of load.The friction test of lubricating oil/grease shows that: the use of PTFE self-lubrication technology can effectively reduce the friction coefficient of the sample surface.Under the condition of oil/grease lubrication,the friction coefficient of the sample decreases first and then increases with the increase of texture density,medium texture density is beneficial to the effect of lubrication.And in oil/grease lubrication medium,the friction coefficientdecreases with the increase of load.By increasing the reciprocating motion frequency,the friction coefficient on the surface of oil-lubricated sample increases,and the friction coefficient on the surface of grease-lubricated sample first increases and then gradually decreases.By comparing the samples with different surface treatments,it is found that PTFE self-lubricating technology combined with micro-texture technology can improve the friction performance of friction pair to the greatest extent.