Study On Friction Torque Characteristics Of Rotary Table Bearing YRT

Rotary table bearing YRT is a high-precision three-row roller slewing bearing that can withstand combined loads.It is widely used in the rotating parts of precision instruments such as machine tools,engineering machinery,and aerospace.The rotation accuracy and performance of the rotating component are directly affected by the magnitude and stability of the friction torque.The research on the friction torque characteristics of rotary table bearing YRT has important theoretical value.In order to study the friction torque characteristics,the static analysis model of rotary table bearing YRT is established by the slicing method under combined load.And the load distribution law of the bearing is analyzed in different axial loads,radial loads,overturning moments and axial clearances.The motion state and the lubrication state of the rotary table bearing YRT is analyzed.And the calculation model of friction torque is established from three sides including the rolling friction between the roller and the raceway,the sliding friction between the roller and the raceway and the viscous friction of the grease,by the energy method based on the above research.The effects of working condition parameters,axial clearance and parameter of roller on the friction torque characteristic of rotary table bearing YRT are studied.The result shows that the friction torque is mainly produced by the upper roller when the rotary table bearing YRT is applied axial load,and there is an inflection point in the curve of the total frictional torque which,before and after the inflection point,is basically proportional to the axial load,but ratio coefficients are different;the friction torque of the rotary table bearing YRT increases with the increase of the overturning moment and the increases amplitude is bigger and bigger;Within the low speed range,its friction torque increases gradually with the increase of rotating speed,but the overall variation range is small;the friction torque of the bearing increases with the decrease of axial clearance and the ratio coefficient increases gradually.The friction torque can be effectively reduced by using less number rollers of upper and lower rows and using thinner diameter rollers with full arc profile modification,under the premise of satisfying carrying capacity.The torque test bench used to measure the friction torque of rotary table bearing YRT was independently designed and developed.By comparing the theoretical calculation values and experimental values of the friction torque of the bearing under different rotational speeds and different axial clearances,it can be concluded that the trend of theoretical calculation values is basically consistent with the experimental values and the maximum error is 17.7%,which is within the scope allowed by the project.The rationality of the theoretical model of the friction torque of YRT rotary table bearing is obtained.The research results will provide a theoretical basis for the design of low friction torque rotary table bearing YRT.