Optimization Of Process Parameters And Study On Friction And Wear Performance Of Thin Walled Ball Bearings

Compared with ordinary bearings,thin-walled ball bearings have excellent performance such as small size,light weight,low friction torque and high rotation accuracy.They are often used in aerospace,precision machine tools,work turntables,radar communications,industrial robots,semiconductor processing equipment,and medical equipment.In order to improve the design concept of thin-walled ball bearings and meet the needs of special matching bearings for high-precision mechanical systems,the design theory,dynamic characteristics and heat treatment process parameters of thin-walled ball bearings are studied,and the optimization design method of key structural parameters of thin-walled bearings is explored.The optimization of parameters is expected to improve the friction and wear performance of thin-walled bearings.First,according to the structural characteristics and working conditions of the thin-walled ball bearing,a full-parameter geometric mathematical model of the thin-walled bearing is constructed.Based on ANSYS/Workbench finite element analysis software,a hollow shaft-thin-walled ball bearing-base flexible contact model was established,and its dynamic characteristics were analyzed.Discuss the influence of variables such as fit clearance,angular velocity,load and structural parameters on the running conditions of rolling elements,the elastic deformation zone of the outer ring,and the distribution of the maximum contact load between the rolling elements and the inner and outer rings.The structural frequency response law of the bearing system under continuous periodic load is analyzed.The study found that the sliding friction between the cage and the ball first occurs when the bearing is subjected to an instantaneous load until it runs stably.After 0.12 s,the sliding friction turns to rolling friction.The maximum stress value and the location where the elastic deformation occurs will shift over time,not at the line of action of the radial force.As the speed and dynamic load increase,the cage will shift and deform significantly.The maximum contact pressure shows a downward trend as the balls increase and the wall thickness decreases,and the load bearing area increases significantly.The low-order natural frequency of the thin-walled bearing has a great influence on its vibration characteristics.The stress and displacement peaks of the bearing appear at750 Hz,and the two have good consistency.The order of the influence of structural parameters on the dynamic characteristics of thin-walled bearings is: inner groove curvature radius>number of rolling elements>outer groove curvature radius>fitting clearance.Secondly,the fatigue life prediction model of thin-walled bearings is established.Comprehensively considering the experimental requirements and conditions of the rolling bearing fatigue life test,the thin-walled bearing 61830 is used as the experimental object,and the BLT-L1 rolling bearing fatigue life testing machine is selected to carry out the fatigue life test of the bearing.Analyze the factors affecting the fatigue life of the bearing and verify the rationality of the life prediction model.The study found that with the increase of load and speed,the bearing contact fatigue life showed a downward trend.The vibration amplitude and temperature of the bearing change with the viscosity of the lubricant.A more viscous lubricant can reduce the vibration amplitude of the bearing,but it will increase the resistance of the bearing and cause the temperature to rise.Lubricating oil viscosity has a certain influence on bearing life,46# lubricating oil can effectively reduce bearing vibration amplitude.The order of influencing factors on bearing fatigue life is load>speed>lubricating medium.Finally,with the goal of improving the friction and wear performance of thin-walled bearings,the changes in the heat treatment structure of the bearing inner and outer rings from the blank to the finished bearing are analyzed.The thin-walled bearing rings are heat treated with different processes,and the main reasons for the main defects of the microstructure of the samples after quenching and tempering are analyzed in depth.Measure the hardness and tensile strength of each sample after treatment,analyze the influence of different heat treatment processes on the friction and wear performance of the bearing from the angle of friction coefficient,wear volume,wear morphology and surface roughness,and discuss its mechanism.Optimize the heat treatment process parameters to improve the contact fatigue performance of bearing materials.The study found that the salt bath quenching method is the most reasonable for the bearing ring,and the comprehensive mechanical properties of the bearing steel at a quenching temperature of 860 ℃ are the best.The content of acicular martensite in the entire matrix structure is the most,and the distribution is uniform,the large block carbides are dissolved,and the carbides are well distributed.At this time,the friction factor is the smallest,and the organization has good anti-friction properties.As the tempering temperature increases,the carbide particles continue to aggregate and expand.When the tempering temperature reaches 280°C,the supersaturated carbon in the martensite begins to desolubilize,and the precipitated carbides continue to accumulate and grow,producing a small amount of tempered troostite.At this time,the hardness and tensile strength of the sample decreased significantly,and the toughness and elasticity increased significantly.