Based on dynamic analysis of rolling bearings, the nonlinear dynamic differential equations of a cylindrical roller bearing with a trilobe-raceway were established and solved by the GSTIFF（gear stiff） integer algori...Based on dynamic analysis of rolling bearings, the nonlinear dynamic differential equations of a cylindrical roller bearing with a trilobe-raceway were established and solved by the GSTIFF（gear stiff） integer algorithm with a variable step. The influences of structural parameters and the tolerance of the trilobe-raceway, working conditions of the bearing, and the outer ring installation method on cage slip characteristics were investigated. The results show that：（i） The cage slip ratio and bearing rating life of a cylindrical roller bearing with a trilobe-raceway would reduce when the low-radius（radius of the outer raceway contour at the lowest point） and D-value（difference value between the high and low points of the outer raceway contour） decrease, and the former（low-radius） contributes more significantly.（ii） The cage slip ratio of a cylindrical roller bearing with a trilobe-raceway rises with the increase of the bearing speed, and decreases with the increase of the radial force; the variation range increases with the increase of the low-radius.（iii） When the installation angle of the outer ring increases in a period, the cage slip ratio remains unchanged while the bearing rating life rises up a little. Therefore, when installing a cylindrical roller bearing with a trilobe-raceway, the location of the maximum radius shall be under that of the radial force to improve the bearing rating life.（iv） With the increase of the roundness of the base circle where the radius of the lowest points of the trilobe-raceway contour locates, the cage slip ratio rises gradually and the bearing rating life decreases.展开更多
This study presents a method for measuring the imbalance in a small-sized cylindrical roller.The roller imbalance was calibrated on the built static-pressure-air flotation measurement machine.The impact of the roller ...This study presents a method for measuring the imbalance in a small-sized cylindrical roller.The roller imbalance was calibrated on the built static-pressure-air flotation measurement machine.The impact of the roller imbalance on the dynamic characteristics of a cage were then studied on the aero-bearing test rig.The displacement spectrums with different roller imbalance of the obtained cage orbits under various bearing speed and radial load were used to evaluate the cage stability.The results show that the cage cannot form a stable operating state at a lower bearing speed with or without the unbalanced rollers.The cage with balanced rollers gradually develops stable motion with the increase of the bearing speed.The existence of a small roller imbalance causes the stability of the cage to deteriorate.With an increase in the bearing speed and radial load,the cage with the unbalanced rollers runs unsteadily accompanied by a high-frequency vibration when the roller imbalance is large enough.The vibration amplitude of the cage in the horizontal direction is greater than that in the vertical direction during an unstable operation,which is similar in the stable status.展开更多
This paper explores an analytical model for Elastic Ring Squeeze Film Damper(ERSFD) with thin-walled ring and turbulent-jet orifices, and uncovers its Oil Film Pressure Performance(OFPP). Firstly, the ring deformation...This paper explores an analytical model for Elastic Ring Squeeze Film Damper(ERSFD) with thin-walled ring and turbulent-jet orifices, and uncovers its Oil Film Pressure Performance(OFPP). Firstly, the ring deformation is addressed by using the Fourier series expansion approach and the orifice outflow rate is characterized with the Prandtl boundary layer theory. Secondly, applying finite difference scheme, the influence of elastic ring flexibility, orifice diameter, and attitude angle on the OFPP is analyzed. Finally, Outer chamber pressure was measured experimentally at different rotor speeds. The results indicate that the outer chamber pressure coats an individual load-carrying region and spreads symmetrically pertaining to the attitude angle. Its amplitude drops as the elastic ring flexibility decreases but boosts with the reduction of the orifice diameter.For inner chamber pressure, the orifice diameter effects a similar trend to the outer cavity, but exhibits more stable distribution regarding the attitude angle. Minimizing the elastic ring flexibility causes an increase in amplitude. The model is validated by the test results giving that the outer chamber pressure shifts synchronously and periodically with the variation of the attitude angle,while the pressure amplitude increases slightly at higher rotor speeds.展开更多
基金financially co-supported by the National Natural Science Foundation of China (U1404514)Henan Outstanding Person Foundation in China (144200510020)the Collaborative Innovation Center of Major Machine Manufacturing in Liaoning, China
文摘Based on dynamic analysis of rolling bearings, the nonlinear dynamic differential equations of a cylindrical roller bearing with a trilobe-raceway were established and solved by the GSTIFF（gear stiff） integer algorithm with a variable step. The influences of structural parameters and the tolerance of the trilobe-raceway, working conditions of the bearing, and the outer ring installation method on cage slip characteristics were investigated. The results show that：（i） The cage slip ratio and bearing rating life of a cylindrical roller bearing with a trilobe-raceway would reduce when the low-radius（radius of the outer raceway contour at the lowest point） and D-value（difference value between the high and low points of the outer raceway contour） decrease, and the former（low-radius） contributes more significantly.（ii） The cage slip ratio of a cylindrical roller bearing with a trilobe-raceway rises with the increase of the bearing speed, and decreases with the increase of the radial force; the variation range increases with the increase of the low-radius.（iii） When the installation angle of the outer ring increases in a period, the cage slip ratio remains unchanged while the bearing rating life rises up a little. Therefore, when installing a cylindrical roller bearing with a trilobe-raceway, the location of the maximum radius shall be under that of the radial force to improve the bearing rating life.（iv） With the increase of the roundness of the base circle where the radius of the lowest points of the trilobe-raceway contour locates, the cage slip ratio rises gradually and the bearing rating life decreases.
基金supported by the National Science Foundation for Young Scientists of China(No.51905152)。
文摘This study presents a method for measuring the imbalance in a small-sized cylindrical roller.The roller imbalance was calibrated on the built static-pressure-air flotation measurement machine.The impact of the roller imbalance on the dynamic characteristics of a cage were then studied on the aero-bearing test rig.The displacement spectrums with different roller imbalance of the obtained cage orbits under various bearing speed and radial load were used to evaluate the cage stability.The results show that the cage cannot form a stable operating state at a lower bearing speed with or without the unbalanced rollers.The cage with balanced rollers gradually develops stable motion with the increase of the bearing speed.The existence of a small roller imbalance causes the stability of the cage to deteriorate.With an increase in the bearing speed and radial load,the cage with the unbalanced rollers runs unsteadily accompanied by a high-frequency vibration when the roller imbalance is large enough.The vibration amplitude of the cage in the horizontal direction is greater than that in the vertical direction during an unstable operation,which is similar in the stable status.
基金supported by the National Natural Science Foundation of China(No.52005158)。
文摘This paper explores an analytical model for Elastic Ring Squeeze Film Damper(ERSFD) with thin-walled ring and turbulent-jet orifices, and uncovers its Oil Film Pressure Performance(OFPP). Firstly, the ring deformation is addressed by using the Fourier series expansion approach and the orifice outflow rate is characterized with the Prandtl boundary layer theory. Secondly, applying finite difference scheme, the influence of elastic ring flexibility, orifice diameter, and attitude angle on the OFPP is analyzed. Finally, Outer chamber pressure was measured experimentally at different rotor speeds. The results indicate that the outer chamber pressure coats an individual load-carrying region and spreads symmetrically pertaining to the attitude angle. Its amplitude drops as the elastic ring flexibility decreases but boosts with the reduction of the orifice diameter.For inner chamber pressure, the orifice diameter effects a similar trend to the outer cavity, but exhibits more stable distribution regarding the attitude angle. Minimizing the elastic ring flexibility causes an increase in amplitude. The model is validated by the test results giving that the outer chamber pressure shifts synchronously and periodically with the variation of the attitude angle,while the pressure amplitude increases slightly at higher rotor speeds.
