The effect of lubricant viscosity on the performance of full ceramic ball bearings

As a new high-end bearing product, full ceramic ball bearings are favoured in a variety. However, there have been few studies on the lubrication of full ceramic ball bearings. The purpose of this study is to reveal the relationship between the vibration and temperature rise of full ceramic angular contact ball bearings and the lubricant viscosity, and to improve the service life of the bearings. In this study, the effects of lubricant viscosity on the vibration and temperature rise of silicon nitride full ceramic angular contact ball bearings under different axial loads and rotation speeds were tested. Herein, a mathematical model of oil lubrication suitable for full ceramic ball bearings is established and the relationship between the lubricant viscosity, lubricant film thickness, outer ring vibration and temperature rise of the bearing is analyzed. It was found that the vibration and temperature rise first decrease and then increase with the increase of lubricant viscosity. In this range, there is an optimal viscosity value to minimize the vibration and temperature rise of the full ceramic angular contact ball bearing. The contact surface wear of the full ceramic angular contact ball bearing varies greatly under different lubricant viscosities. There is no obvious wear on the contact surface under optimal viscosity, and the service life of the bearing is greatly improved. These results can play an important role in revealing the lubricant mechanism of full ceramic ball bearings and improving their service life under optimal lubrication.

Experimental Investigation of Clearance Influences on Cage Motion and Wear in Ball Bearings

Clearances of cages in ball bearings, including pocket and guiding clearances, play a vital role in the stability and reliability of bearings. In this paper, experiments on the cage motion and wear were carried out to investigate the influence of clearances in ball bearings. Firstly, the cages with a series of pocket and guiding clearances were specially designed and tested for prescribed operating conditions on a bearing test rig in which the cage motions were measured, and corresponding wear was also observed. Then, the normalized trajectory, waveform, and spectra of cage motion were constructed and compared to illustrate the effects of clearances on the cage motion and then to establish the relationship between cage motion and wear. Results reveal that the cage motion and wear are both significantly affected by its clearances. The increment of cage guiding clearance makes the whirl trajectories of the cage regular and the motion frequency of cage motion significantly change. However, the increment of cage pocket clearance make the whirl trajectories change from well-defined patterns to complicated ones, and the frequency of cage motion apparently changes. Additionally, the bearing wear is closely related to the cage motion. If the inner ring frequency is of domination for the cage motion, the cage guiding surface will wear seriously. While cage motion is dominated by two times cage frequency in spectrum domain, the cage pocket will wear more seriously.

Review on the Thermal Performance on the Basis of Different Types of Material used in Ball Bearings

Bearing is a movable object, so frictional forces must be overcome in terms of moving the Bearing. To decrease the friction force on the movable methodology, different kinds of bearings have been used. The bearing gets its characterized by the fact that it is used to support a rotating axle or shaft. Because rolling bearings utilize balls or rollers, they are referred to as "rolling components." one can measure bearing expected lifespan depending on the material exhaustion if one can understand the operations and maintenance of loads and speeds. These computations should be based on the assumption that now the bearing is appropriately installed, lubricated, and moreover treated. It is unable to account for the impact of detrimental operating environment. Damaged bearing has a significant economic and industrial implications. Numerous substance are used in the bearing sector to several bearing elements. To achieve maximum bearing performance and durability, the products are deposited to obtain intended characteristics. The components listed in this are the most frequently used. The different materials used in ball bearings are discussed in this paper.

A geometric calibration approach for industrial cone-beam CT system based on low-rank phantom

Precise alignment of the system scan geometry is crucial to ensure the reconstructed image quality in the cone-beam CT system. A calibration method that depends on the local feature of ball bearings phantom and point-like markers is probably affected by local image variations. Besides, multiple projections with circular scanning are usually required by this type of method to derive misaligned parameters. In contrast to previous works, this paper proposes a method that depends on the global symmetric low-rank feature of a novel phantom, which can accurately represent the system geometrical misalignment. All the misaligned parameters of the cone-beam CT system can be estimated from a single perspective direction without circular scanning. Meanwhile, since the global low-rank feature of the phantom is utilized, the proposed method is robust to the noise. Extensive simulations and real experiments validate the accuracy and robustness of our method, which achieves better performance compared to an existing phantom-based method.

Bearing life calculations in rotating and oscillating applications

This paper begins by describing standard bearing life models in continuous rotation before going on to explain how the bearing life can be calculated for roller and ball bearings in oscillatory applications. An oscillation factor a_osc is introduced which accounts for the oscillating and stationary ring. This can be calculated numerically as a function of the oscillation angle θ and load zone parameter ε as well the parameters γ =D·cos(a)/dm and the ball-race osculation factors. Critical angles as used by Rumbarger are also employed at low θ values. Appropriate curve-fitted relationships for both roller and ball bearings are then given for a simple calculation of aosc with an accuracy of approximately 10%. Finally, several methods are suggested for estimating the ε parameter using a real case with a Finite Element Analysis load distribution accounting for structural ring deformation and ball-race contact angle variations. The results derived in this paper allow the lifetime of any arbitrary oscillating ball or roller bearing to be calculated.

Investigation of oil-air flow and temperature for high speed ball bearings by combining nonlinear dynamic and CFD models

An improved nonlinear dynamic model of high speed ball bearings with elastohydrodynamic lubrication (EHL) is adopted to predict the movements of balls and power loss of ball bearings for defining the boundary conditions of computational fluid dynamics (CFD) model. Then, this method of combining nonlinear dynamic and CFD models is are validated through the experimental verification. Subsequently, oil-air flow and temperature distribution inside the bearing chamber are studied at low and high speeds, and light and heavy loads. The effect of nozzle's position on the formation of oil film and heat dissipation is revealed under combined loads. The research results provide a theoretical basis for engineering application of high speed rolling bearings.