Study On Sealing Performance Of Sealing Unit In Rolling Bearing

Sealed rolling bearing(the rolling bearing with sealing unit)is widely used in rotating machinery,which can simplify the host structure,facilitate installation and maintenance,and eliminate the pollution of the surrounding environment to the rolling bearing.The failure of sealing unit is the main cause of lubricant leakage of the sealed rolling bearing.The research shows that more than 80% of the bearing early failure comes from the lubrication problem of the bearing.Therefore,establishing the sealing performance analysis model of the rolling bearing sealing unit and carrying out the sealing performance research have theoretical guiding significance and important engineering application value for the design and application of the rolling bearing sealing unit.Aiming at the static sealing unit and dynamic sealing unit of rolling bearing,with the support of the enterprise entrusted project "sealing performance analysis of automobile hub bearing unit" and the national scientific and technological research project "localization development of airframe rod end bearing",this paper studies the sealing performance of static sealing unit such as automobile hub bearing and dynamic sealing unit such as the airframe rod end bearing.The main research work and results of this paper are as follows:(1)According to the Mooney-Rivlin constitutive model of the rubber,the relationship between shore hardness and Mooney-Rivlin material constant of the rubber was deduced,which provides the required material parameters for the study of sealing performance.(2)Aiming at the early failure of the static sealing unit such as the automobile hub bearing,a static sealing unit with the combination of nylon retainer and O-ring was designed.A semi-simplified finite element analysis method of rigid-flexible coupling was proposed for such static sealing unit,and its effectiveness was verified.The effects of O-ring compression ratio,O-ring material hardness and sealing structure parameters on the static sealing performance were studied.The three factor and four level orthogonal experimental design was used to improve the efficiency of the static sealing unit.The limit operating pressure of automobile hub bearing static sealing unit was studied,and the limit operating pressure curve was obtained.Finaly,builded a static sealing performance test bench for automobile hub bearing,and carried out relevant test verification.The results show that: the semi-simplified finite element model is more suitable for the sealing performance analysis of static sealing unit with the combination of nylon retainer and O-ring.The static sealing performance test shows that the limit operating pressure curve of automotive hub bearing static sealing unit is basically reasonable.The designed static sealing unit can solve the problem of lubrication failure of automobile hub bearing.(3)Aiming at the early failure of the dynamic sealing unit such as the airframe rod end bearing,a thermal-stress coupling analysis model of dynamic sealing unit based on bearing dynamics was established,and the influence of the sealing unit on the dynamic sealing characteristics was studied.Taking the maximum contact stress between the sealing unit and the rotating ring and the maximum equivalent stress of the sealing ring as the evaluation parameters of the dynamic sealing characteristics,the efficiency increasing design of the dynamic sealing unit was carried out.The results show that: 1)In terms of dynamic sealing unit parameters,the primary and secondary order affecting the maximum contact stress between dynamic sealing unit and rotating ring is: hardness of the sealing ring material,thickness of the sealing ring,inner diameter of the metal skeleton,inner diameter of the sealing ring and axial size of the metal skeleton.The primary and secondary order affecting the maximum equivalent stress of the sealing ring is: hardness of the sealing ring material,axial size of the metal skeleton,thickness of the sealing ring,inner diameter of the metal skeleton and inner diameter of the sealing ring.2)In terms of bearing operating condition parameters,the maximum contact stress between dynamic sealing unit and rotating ring increases with the increase of oscillating frequency and oscillatinga mplitude,and decreases with the increase of bearing cavity temperature.3)The reliability of the dynamic sealing unit of the airframe rod end bearing is improved,the sealing performance is more stable,and the friction torque of the bearing is reduced after the efficiency increasing design.(4)Based on the Archard model,the wear depth was calculated,and a modeling technology of model reconstruction and mesh reconstruction was proposed,and the finite element model of the sealing ring wear characteristics was constructed.The wear characteristics of sealing ring were studied,and the wear evolution process of sealing ring was revealed.The results show that: 1)In terms of dynamic sealing unit parameters,the wear of sealing ring increases with the increase of shore hardness and wear rate of sealing ring material,and is less affected by Poisson’s ratio of sealing ring material.The inner diameter of the sealing ring,the axial size and inner diameter of the metal skeleton have a great and complex influence on the wear of the sealing ring.2)In terms of bearing operating condition parameters,the wear of sealing ring increases with the increase of bearing oscillating frequency and oscillating amplitude,and is less affected by the temperature of bearing cavity.(5)The dynamic sealing performance test bench was built.The dynamic sealing performance test shows that the average grease retention rate of the dynamic sealing unit in the airframe rod end bearing increases by 17.3%,the starting torque of the bearing decreases by 33.3%,and the sealing performance of the dynamic sealing unit is greatly improved after the efficiency increasing design.Due to the special application of sealed rolling bearing,the sealing performance is more important than its fatigue life in a sense.Therefore,it is of practical significance to study the sealing performance of the sealing unit.Theoretically,this paper provides an effective research method for the research on the sealing performance of static /dynamic sealing unit and the efficiency design of sealing unit in rolling bearing,further improves the dynamic model of rolling bearing,and strives to make a theoretical breakthrough in the design of rolling bearing sealing unit.In terms of application,the research results of this paper can solve the problem of early failure of automobile hub bearing static sealing unit and airframe rod end bearing dynamic sealing unit,It is expected to provide reference for the design and application of rolling bearing sealing unit.