Search

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The stability analysis of spherical hybrid sliding bearings includes exploring its dynamic characteristics and critical speed, its stiffness and damping coefficient have an important impact on the stability of the bearing-rotor system, and the study of critical speed can effectively avoid whirl instability in the bearing-rotor system. The boundary slip conditions are considered to analyze the stability of spherical hybrid sliding bearings. Taking the flow of the small hole restrictor into the oilcavity equal to the flow out of the oil sealing edge as the boundary condition, the Reynolds equation in the boundary slip state is solved to obtain the oil cavity pressure and the oil sealing edge pressure. For the transient Reynolds equation in the boundary slipstate, the equation uses the small perturbation method to derive the partial differential equation of the perturbation pressure, and combines the finite difference method and the relaxation iterative method to solve the equation to obtain the stiffness and damping coefficient of the ball bearing under the state of boundary slip, and then establish the shafting trajectory equation to solve the instability speed. The influence of slip coefficient, oil supply pressure, rotor speed on the dynamic characteristics of the bearingand the variation law of the instability speed on the slip coefficient are discussed. The results show that the increase of the slipcoefficient will lead to the decrease of the four stiffness coefficients and the cross damping coefficients, and the increase of thedirect dampings. The increase of the oil supply pressure will lead to the increase of the eight dynamic characteristic coefficients, and the increase of the rotational speed will lead to the increase of the stiffness and the decrease of the dampings, and the occurrence of slip effect does not affect the above rules. The instability speed decreases with the increase of slip coefficient, so the system stability decreases.

Copyright of Journal of Mechanical Strength / Jixie Qiangdu is the property of Zhengzhou Research Institute of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The oil film temperature of the spherical hybrid sliding bearings would increase due to the friction and shear of the lubricating oil at high speed or super high speed, which leads to the thermal deformation of bearing and rotor. As a result, the deformation seriously affects the rotation accuracy of the spindle, because it is in the same order of magnitude as the oil film thickness. Therefore, the fluid lubrication mathematical model is established by taking the spherical hybrid sliding bearings with orifice throttling mode as the research object, and the Reynolds equation and energy equation of lubricating oil film are derived. The pressure distribution and temperature distribution of oil film of the spherical hybrid sliding bearings are calculated by combining the finite difference method and relaxation iteration method. The influence of working parameters on bearing capacity and oil film temperature rise was investigated. The results show that the oil film shear effect is stronger and the temperature rise increases with the increase of rotating speed and the decrease of oil film thickness. When the speed is 3 000 r/min and the oil film thickness is 28 μm, the maximum temperature rise of the bearing is 18.65 K higher than that of 1 000 r/min. When the speed is 3 000 r/min and the oil film thickness is 20 μm, the maximum temperature rise of the bearing is 27.685 K higher than that of the oil film thickness of 28 μm.

Taking the spherical sliding bearings with orifice throttling as the research object, the mathematical model of lubrication of spherical hybrid sliding bearings is established and the Reynolds equation under laminar flow state is deduced from this model. The pressure distribution of the oil chamber and oil edge are calculated according to the flow conservation principle of the orifice throttle. Combining with the finite difference method and relaxation iterative method to solve the disturbance pressure control equation which is derived by means of perturbation method. The stiffness coefficient and damping coefficient of spherical sliding bearings are used to study the influence of supply pressure, rotating speed, average oil film clearance and other parameters on the dynamic characteristics coefficient of the bearing through numerical analysis. The results show that as the oil film clearance decreases and the oil supply pressure increases, the stiffness coefficient and damping coefficient will increase accordingly. As the rotating speed increases, the changing trend of the direct stiffness is small while the decreasing trend of the direct damping is obvious. When the oil film clearance is 20 μm, the stiffness coefficient and damping coefficient of spherical hybrid sliding bearings reach the maximum. The increasing of rotating speed has little effect on the stiffness while the damping coefficient will be significantly reduced.

Copyright of Journal of Mechanical Strength / Jixie Qiangdu is the property of Zhengzhou Research Institute of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Mechanical Strength / Jixie Qiangdu is the property of Zhengzhou Research Institute of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Analyzing the influence of bearing parameters on the dynamic characteristics of spherical sliding bearings, which provided theoretical guidance for the operating stiffness, damping and stability of liquid spherical bearings. Taking spherical hybrid sliding bearings as the research object, established the mathematical model of lubrication analysis of spherical sliding bearings, the dynamic liquid lubrication equation under laminar flow was derived by the perturbation method, the partial differential equation of disturbance pressure was solved by the finite difference method, and the liquid was calculated numerically. The stiffness coefficient and damping coefficient of the spherical bearing were used to study the influence of the bearing speed, eccentricity, average oil film clearance and other parameters on the dynamic characteristic coefficient of the bearing through numerical analysis. The results show that the speed、 eccentricity and average oil film clearance have an important influence on the stiffness and damping of the oil film.

Aiming at the lubrication characteristics of spherical hybrid sliding bearings（ SHSBs） for an ultra-high precision grinding machine,the Reynolds equations often adopt more assumptions,and the calculation accuracy cannot meet the design requirements of ultra-high precision bearings. The pressure and temperature field distribution characteristics of SHSBs was analyzed by CFD software based on N-S equations. And the variation law of structural parameters and working parameters on load capacity,flow and temperature rise,as well as the coupling effect between various parameters was explored. Based on this,the orthogonal experimental design method was used to obtain the optimal parameter combination of SHSBs under the premise of meeting the multi-objectives of high load and low temperature rise. The results show that these parameters significantly affect the bearing capacity and temperature rise of the bearing,and there are also cross-coupling effects. The analysis results are instructive for further research on the design of SHSBs.