Elastohydrodynamic Lubrication Study On Multi-body Of Deep Groove Ball Bearing

The rolling element bearing is widely used in mechanical system,whose lubrication performance affects directly the whole performance of the system.However,most of the past elastohydrodynamic lubrication(EHL)studies of ball bearings focused on the lubrication analysis of a single lubricated contact zone,and there are few researches related to the multi-body EHL(MBEHL)which considers the interaction of multiple lubricated contact zones.In the rolling bearing's running process,the rolling elements interact with each other,and the rolling element and the inner/outer rings interact with each other,so it is necessary to carry out the MBEHL research of the ball bearing.Sponsored by the National Key R&D Program of China(No.: 2017YFB1300700)named after "RV reducer digital and efficient precision manufacture" and the National Natural Science Foundation of China(No.: 51775067)named after "Study on multi-body lubrication and thermal performance for a high-speed rolling bearing considering the rotor dynamic effect",the MBEHL performance of the deep groove ball bearing is studied in this paper.The main research contents are stated as follows:Firstly,a MBEHL model with multiple rolling elements(MREs)in contact with the outer ring of the deep groove ball bearing was established and solved with the Fast Fourier Transform(FFT)technique and low relaxation iteration method.Then,the EHL performances for the central rolling element among the MREs were analyzed and compared with the EHL characteristics for the single rolling element(SRE)in contact with the bearing's outer ring.The numerical results show that,compared with the SRE EHL,the central film thickness of the central rolling element among the MREs increases,whose load-carrying capacity decreases by from 5.99% to 9.70% when the radial displacement of the central rolling element increases from 10 to 30 ?m.Secondly,a MBEHL optimization model for the deep groove ball bearing was established,and an optimization algorithm based on the complex method was proposed.The load and moment balance equations of the rolling element were converted into the objective function,the revolution and rotation angular velocities of the rolling element were selected as independent variables,the friction forces between the rolling elements and the inner/outer rings were obtained by solving the EHL model.Finally,the MBEHL parameters,motion parameters and load parameters under the balance of the rolling element and the inner/outer ring are obtained by making the objective function approach zero.After that,based on the MBEHL optimization model,the MBEHL performances of the deep groove ball bearing were studied.The results show that,the increases in the elastic modulus and the arithmetic mean deviation of the surface roughness for the inner ring increases the film thickness between the maximum loaded rolling element and the outer ring.With the increase of oil-gas percentage,the film thickness between the maximum loaded rolling element and the inner ring increases,while the film thickness between the maximum loaded rolling element and the outer ring decreases.With the increase of the number of rolling element,the film pressure between the maximum loaded rolling element and the inner/outer ring decreases.As the radial clearance increases,the film pressures between the maximum loaded rolling element and the inner/outer rings increase and the film thicknesses between the maximum loaded rolling element and the inner/outer rings decrease.As the initial viscosity of the lubricant increases,the film thicknesses between the maximum loaded rolling element and the inner/outer rings increase.As the characteristic shear stress of the lubricant increases,the film thickness between the maximum loaded rolling element and the outer ring increases.Lastly,based on the traditional frictional heat generation model modified,a frictional heat generation model of deep groove ball bearing considering the influence of MBEHL was established,which considers the influence of EHL on the frictions between the rolling element,the inner/outer rings and the cage.It is found that the friction heat generation rate of the deep groove ball bearing calculated by present model is more practical compared with the traditional method.Considering MBEHL,the increase of the oil-gas percentage and initial viscosity of the lubricant both make the friction heat generation rate of the deep groove ball bearing increase.With the increase of characteristic shear stress of the lubricant,the friction heat generation rate of the deep groove ball bearing is reduced.