The Research On Synergistic Effects Of Ultrasonic Surface Rolling Process And Surface Texture For Aviation Spherical Plain Bearing

As the key fundermental parts of the aircraft landing gear,actuators and other important components,aviation spherical plain bearings often undergo unidirectional loads,heavy shock loads and neglected lubrication intervals.In such extreme ambient conditions,they are prone to appear abrasion failure.In order to meet the requirements of increasing high wear resistance of aviation spherical plain bearings,a compound method of ultrasonic surface rolling process and surface texture was proposed.This strengthening method greatly enhance the surface quality and the micro hardness of the specimen.At the same time,lubrication condition is improved.The synergy effects of surface strengthening and surface texture can significantly improve the wear resistance and extend the service life.The friction pairs of aviation spherical plain bearings are 304 stainless steel and 9Cr18stainless steel.The surface topography,surface roughness and micro hardness of the 304stainless steel plates were observed by changing the machining parameters of ultrasonic rolling strengthening.After the friction and wear experiment,the friction coefficient between9Cr18 stainless steel balls and 304 stainless steel plates strengthened by different parameters were compared.The abrasion loss and the morphology of wear zone were also analyzed.Finally,ultrasonic rolling and surface texture were used to strengthen the 304 stainless steel plate synergistically.According to the results,the rule of the mechanical properties and the friction and wear properties of specimens is influenced by ultrasonic rolling strengthening parameters,such as static pressure,rolling times and spindle speed,and different forms of surface texture.The experimental observation and research show that the parameters of ultrasonic surface rolling process has different influence on the surface topography,the surface roughness and the hardness of the specimens.Increasing the static pressure,rolling times and spindle speed within limits can improve the surface quality and the micro hardness,however,the effects of surface strengthening may be hardly reached with too low process parameters,and the hardened layer may be damaged with too high process parameters.At the same time,the surface quality,the surface roughness and the hardness affect the friction and wear properties directly.The specimens with low surface roughness and high micro hardness have better wear resistance and longer service life.The synergistic effect of ultrasonic rolling and surface texture is better than the single effect of ultrasonic surface rolling.Compared with the smooth surface without texture,the wear volume and the friction coefficient between the surface with a square pit texture of 304 stainless steel and the 9Cr18 stainless steel ball is lower.The friction coefficient is about 0.1,and the wear volume is about 2.7×10~5μm~3.The wear volumeloss of the 9Cr18 stainless steel ball is also smaller than others.In addition,it is proved that graphene lubricating oil can further improve the lubrication effect between friction pairs of spherical plain bearings.