High-speed Ball Bearings Research Articles

Optimization of the lubrication conditions for minimization of the operating temperature of the high-speed ball bearings

Bearing lubrication for high speed application (above 20,000 rpm) has significant influence on the bearing heat generation and consenquently bearing operating temperature. For application in aerospace industry the selection of lubricant type, its amount and lubrication method should be carefuly conducted in order to achieve desired life and minimal weight. In this paper, experimental research was carried out in order to check whether and to what extent an open loop system can achieve similar bearing thermal behaviour as in a closed loop system. Tests were conducted on high-speed bearings of a turbo shaft engine. The experimental results showed that the open loop system, with oil mist lubrication, can achieve similar bearing operating temperature as the closed loop system, which operates with oil circulation, with the advantage of having a significantly lower mass. Also, a variation of lubrication conditions for open loop method, air pressure and oil amount, was carried out in order to minimize the operating temperature of high speed angular ball bearings. It has been shown that there is a combination of these two parameters that gives the least heating of high-speed bearings.

A study on the temperature rise characteristics of high-speed ball bearings under starvation lubrication

PurposeThis paper aims to study the problem of starvation lubrication of high-speed ball bearings due to temperature rise during operation and to avoid thermal failure of bearing lubrication.Design/methodology/approachUnder the quasi-statics model of grease lubrication, both the oil film dragging force and the rolling friction between the balls and raceways collectively counteract the gyroscopic torque. Initially, the static model for grease lubrication is solved, followed by calculating the generated heat using the local heat generation method and ultimately the multinodal thermal network model is solved, and the solved results of the quasi-statics are updated by the temperatures of the grease nodes based on the relationship of the grease temperature and viscosity, as well as the relationship of the viscosity and the film thickness.FindingsBy comparing the numerical calculation results of bearings under different working conditions, the influence of starvation lubrication on the oil film thickness, oil film drag force and rolling friction of bearings is discussed, and it is found that the numerical calculation results of the outer ring temperature of bearings under the starvation lubrication due to the consideration of temperature rise are closer to the experimental values.Originality/valueThis study reveals the dynamic characteristics of bearings under starvation lubrication, which is more practical and engineering guiding significance for the design of bearings, and introduces a new method and basis for the calculation of temperature rise of rolling bearings.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2024-0208/

Optimization of high-speed angular contact ball bearing for aircraft gearbox utilizing an evolutionary multi-objective algorithm, NSGA-III

We develop a program for predicting bearing performance, including the maximum contact stress, bearing power loss, minimum lubricating film thickness, static safety factor, and dynamic life, and an optimal design for high-speed angular contact ball bearings in aircraft gearboxes using optimization algorithms. A program is developed to predict bearing performance by calculating the loads and displacements of individual balls based on the bearing’s kinematic and static equilibrium equations. Next, an optimization program is developed with non-dominated sorting genetic algorithm III (NSGA-III), wherein calculated bearing performance indicators serve as constraints or objective functions. The performance of individuals within the final Pareto front is evaluated using the inter-criteria correlation (CRITIC) and weighted product methods. The optimization performances of NSGA-III and NSGA-II are compared based on their hypervolume indicators. A solution of the kinematic and static equilibrium equations under the load cases and duty cycles of real aircraft gearboxes is obtained, enhancing the prediction accuracy. Furthermore, optimization, including bearing performance metrics rarely considered in previous studies, is performed. Optimal specifications superior to reference bearings employed in aircraft gearboxes are obtained, enhancing all three objective functions or specific objective functions. The optimization performance of NSGA-III is confirmed to surpass that of conventional NSGA-II.

Dynamic characteristics of high-speed angular contact ball bearings considering the coupling of outer race waviness and local defects

This paper proposes a novel four degrees of freedom model of angular contact ball bearings (ACBBs) under high-speed effect, in order to characterize the dynamic behavior of rolling bearings with coupling waviness and local defects on the outer race in detail. Firstly, based on bearing quasi-static model, considering centrifugal force, gyroscope moment, the bearing contact stiffness is calculated. Then, the representation model of outer race waviness and the time-varying displacement excitation expression of the bearing with local defects are put forward respectively. On the basis, a dynamic model of ACBBs with coupling factors is built. Finally, the vibration characteristics of the bearing with faults are investigated, the model is verified by the existing experimental results and the influence of different parameters on the bearing dynamics is analyzed. The results show that the bearing fault characteristic frequency is unchanged when the high-speed effect is considered, but the vibration amplitude is smaller than that without the high-speed effect. With the increase of speed, the bearing fault characteristic frequency and vibration amplitude increase. When considering the coupling of outer race waviness and local defects, with the increase of the two factors, the bearing fault characteristic frequency remains unchanged but the vibration amplitude increase.

Study on the Effect of Thermal Characteristics of Grease-Lubricated High-Speed Silicon Nitride Full Ceramic Ball Bearings in Motorized Spindles

Grease lubrication is cost-effective and low-maintenance for motorized spindles, but standard steel bearings can fail at high speeds. This study focuses on high-speed full ceramic ball bearings lubricated with grease. The coefficient of friction torque in the empirical formula is corrected by establishing the heat generation model of full ceramic ball bearing and combining it with experiments. A simulation model of grease flow is established to study the influence of grease filling amount on grease distribution. The simulation model of the temperature field of a full ceramic ball bearing is established to analyze the influence of rotating speed on bearing heat generation, and experiments verify the calculation results of the theoretical model. The results show that an optimal grease filling amount of 15~25% ensures even distribution without accumulation. Additionally, when the amount of grease is constant, the outer ring temperature increases with higher rotating speeds. The test results show that when the grease filling is 0.9~1.2 g, it accounts for about 9~12% of the volume of the bearing cavity, and the temperature of the outer ring is the lowest. At a rotation speed of 24,000 rpm, the outer ring temperature of the grease-lubricated bearing is 50.1 °C, indicating a reasonable range for use in motorized spindles. It provides a theoretical basis for the optimization design of macro-structural parameters of full ceramic ball bearings in the future, which can minimize heat generation and maximize bearing capacity.

Visualization of oil-lubrication ball bearings at high rotational speeds

Deep-groove ball bearings for the eAxles of electric vehicles must adapt to higher rotational speed conditions because the speed of eAxle motors have been increasing as the size and weight of the motors decrease. Therefore, understanding the oil-lubricated conditions inside ball bearings at high rotational speeds is essential for optimizing their design for eAxles. To clarify the oil-lubricated conditions inside ball bearings at these high speeds, a new test apparatus was developed. This apparatus is capable of simultaneously measuring the friction torque of deep-groove ball bearings, the oil-film thickness on the rolling balls, and observing the oil distributions inside the bearings at rotational speeds up to 20,000 min-1. The oil-film thickness was measured using three-wavelength optical interferometry, and the oil distribution was observed using fluorescence. It was found that the oil-film thickness became constant at rotational speed conditions exceeding approximately 7,700 min-1. Oil starvations were observed on the raceway around the rolling ball, and these regions increased with increasing rotational speeds. Additionally, in the deep-groove ball bearing with a crown-shaped cage, the oil was mainly supplied to the rolling balls from the inner ring side through the space between the cage claws that held the ball. Moreover, the amount of mixed air tended to increase as the rotational speed increased to approximately 7,700 min-1. Those oil starvations and increasing air in oils were considered to be factors that prevent the increase in oil-film thickness. The findings of the reported study will contribute to the development of multibody dynamic technology for high-speed ball bearings necessary in electric vehicles.

Measurement of Oil-Film Thickness and Observation of Oil Distribution in High-Speed Deep-Groove Ball Bearings

Measurement of Oil-Film Thickness and Observation of Oil Distribution in High-Speed Deep-Groove Ball Bearings

Diagnosis of High-Speed Ball-Bearing Spindles by Data Mining of Dynamic Responses from Various Rotating Elements

Diagnosis of High-Speed Ball-Bearing Spindles by Data Mining of Dynamic Responses from Various Rotating Elements

A thermal assessment simplification exploration for the structural constraint effect on bearing temperature

Although an extensive research effort on the structural constraint role in bearing heating was done by scholars, often many researchers either neglected the sub structure effect for model simplification or considered more influencing factors to construct a complicated thermal model for higher evaluation precision. As a result, a lightweight and accurate assessment has been not available so far. Furthermore, they usually only made some basic assumptions and qualitative analyses when creating and improving the thermal predictive models to explore the heat transfer of bearings, and hence their findings usually lack sufficient theoretical supports, especially the quantitative bases. For an efficient assessment, this paper devotes to exploring how the structural constraint impact on the heat conduction of bearings, and accordingly present a more practical thermal grid to evaluate bearing heating efficiently. Firstly, the structure and installation notes of bearings were statistically analyzed. Next, a formula was constructed to implement the contrast of the heat transfer capacity between the axial and radial directions of bearing rings, and then a novel radial thermal equivalent resistance was proposed to represent the heat conduction capacity of bearing rings. We accordingly optimized the bearing node setting scheme to develop an efficient semi-empirical thermal grid for high-speed angular contact ball bearings, in which the oil-air separation and gray-box theory was also introduced to describe the heat convection in bearing cavities. Finally the improved thermal network for a motored spindle was planned to verify the above-proposed work, and the simulation results based on the current thermal models of bearings were also obtained and contrasted with the experimental values. For a further validation, the polynomial interpolation on test data, meanwhile, was performed to observe the temperature variation trend. The result of comparative analysis indicates that we show a more proper thermal assessment on bearing temperature.

Numerical and experimental investigation on ball motion with oil rheology and thermal effect in high speed ball bearings

Dynamic behavior of rolling elements determines the performance including the extent of skidding and wear in ball bearings, which are influenced by many factors. A comprehensive investigation of dynamic behaviors of high speed ball bearings has been conducted both numerically and experimentally. The dynamic model of high speed ball bearings applicable to a wide range of shaft speeds has been developed, taking into account rheological behavior of lubricating oil, curvature effect, collision between balls and cage and thermal effect. Analyses of ball speeds and interaction forces, as well as sliding speed within ball-raceway contact ellipse have been carried out. The ball-to-race ratio (BRR) of speed has been studied specifically under various operating conditions to reflect the cage speed with high precision. A set of experiments have accordingly been performed on a test rig where optic fiber transducer was employed to obtain the orbital speed of ball. The increase of orbital speed of ball with shaft speed was observed in experiments under different axial load. Numerical results from dynamic simulations also agree with the experimental results based on the investigated ball bearing. The present model is versatile over a wide range of operating conditions.

An efficient thermal model for high-speed angular contact ball bearings based on oil-air two-phase flow and gray-box model

PurposeFor a lightweight and accurate description of bearing temperature, this paper aims to present an efficient semi-empirical model with oil–air two-phase flow and gray-box model.Design/methodology/approachFirst, the role of lubricant/coolant in bearing temperature was discussed separately, and the gray-box models on the heat convection inside a bearing cavity were also created. Next, the bearing node setting scheme was optimized. Consequently, a novel semi-empirical two-phase flow thermal grid for high-speed angular contact ball bearings was planned. With this model, the thermal network for the selected motored spindle was built, and the numerical solutions for bearing temperature rise were obtained and contrasted with the experimental values for validation. The polynomial interpolation on test data, meanwhile, was also performed to help us observe the temperature change trend. Finally, the simulations based on the current models of bearings were implemented, whose corresponding results were also compared with our research work.FindingsThe validation result indicates that the thermal prediction is more accurate and efficient when the developed semi-empirical oil–air two-phase flow model is employed to assess the thermal change of bearings. Clearly, we provide a more proper model for the thermal assessment of bearing and even spindle heating.Originality/valueTo the best of the authors’ knowledge, this paper introduced the oil–air separation and gray-box model for the first time to describe the heat exchange inside bearing cavities and accordingly presents an efficient semi-empirical oil–air two-phase flow model to evaluate the bearing temperature variation by using thermal network method.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2023-0180/

Dynamic Temperature Prediction on High-Speed Angular Contact Ball Bearings of Machine Tool Spindles Based on CNN and Informer

This study addressed the issues related to the difficulty of determining the operating status of machine tool spindle bearings due to the high rotational speeds and rapid temperature fluctuations. This paper presents an optimized model that combines Convolutional Neural Networks (CNNs) and Informer to dynamically predict the temperature rise process of bearings. Taking the H7006C angular contact ball bearing as the research object, a combination of experimental data and simulations was used to obtain the training dataset. Next, a model for predicting the temperature rise of the bearing was constructed using CNN + Informer and the structural parameters were optimized. Finally, the model’s generalization ability was then verified by predicting the bearing temperature rise process under various working conditions. The results show that the error of the simulation data source model was less than 1 °C at steady state; the temperature error of the bearing temperature rise prediction model was less than 0.5 °C at both the temperature rise and steady-state stages under variable rotational speeds and variable load conditions compared to Informer and Long Short Term Memory (LSTM) models; the maximum prediction error of the operating conditions outside the dataset was less than 0.5 °C, and the temperature rise prediction model has a high accuracy, robustness, and generalization capability.

Dynamics-Based Thermal Analysis of High-Speed Angular Contact Ball Bearings with Under-Race Lubrication

The paper mainly studied the temperature rise characteristics of under-race lubricated high-speed angular contact ball bearings under operational conditions from the perspective of dynamics. The steady-state calculation model of the bearing was established using a thermal network method in consideration of the influence factor of friction power consumption in bearing components based on a dynamic model. Following this, the steady-state change characteristics of the bearing were obtained by solving a thermal balance equation. Through this process, the influence laws of bearing rotation speed, oil supply, and environmental temperature on the friction temperature rise of the bearing were analyzed. Finally, the finite element analysis software ANSYS was employed to provide comparative verification. The results showed that the bearing temperature nonlinearly increased with the increase in inner ring rotation speed, and when it approached a certain critical value, the outer ring temperature exceeded the inner ring temperature. It had an obvious effect on controlling the temperature rise of the bearing inner ring by way of increasing the quantity and reducing the temperature of the lubricating oil supply. Comparative verification showed that the speed–temperature variation tendency from the dynamics-based thermal analysis well agrees with that of the finite element analysis.

A numerical study of fatigue life in high-speed angular contact ball bearings with thermal and centrifugal expansion

PurposeFix-position preloading, centrifugal force and higher temperatures cause the bearing units in angular contact ball bearings to expand, changing the contact load and affecting bearing life. This study aims to examine the effect of thermal and centrifugal expansion on the fatigue life of fix-position preloaded angular contact ball bearings in high-speed operating conditions.Design/methodology/approachThe contact loads on the inner and outer bearing rings were resolved according to the thermal and centrifugal expansion factors in the quasi-static position preloading model. The pressure and frictional stress distribution were used to calculate the subsurface stress in the contact area, while the Zaretsky model was used to determine the relative fatigue life of the inner and outer bearing rings.FindingsUnder fix-position bearing preloading, thermal and centrifugal expansion significantly affected the contact load and relative fatigue life. At the same axial preload, the inner ring contact load was higher than the outer ring contact load, with a maximum difference of 132.3%. The decrease in the inner ring relative life exceeded the outer ring contact load, with a maximum difference of 7.5%, compared to the absence of thermal and centrifugal expansion.Originality/valueThis study revealed the influence of thermal and centrifugal expansion on the fatigue life of angular contact ball bearings in high-speed service conditions.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0065/

Modeling and dynamic characteristic analysis of high speed angular contact ball bearing with variable clearance

In this paper, an analytical calculation model based on Jones raceway control hypothesis model was proposed for high-speed ball bearing, clearance, centrifugal displacement and thermal deformation are considered. The validity of the proposed model was verified by comparing with the Jones model, and the fatigue life model of bearing was established. The bearing dynamic characteristics under axial load and combined load are analyzed, and the change rule of each parameter is revealed. In addition, the influence of different clearances on high-speed bearing is studied, and the dynamic characteristics of bearing are further analyzed. The research show that the proposed model can break the limitation of Jones raceway control hypothesis model, and the bearing ball-raceway contact state and fatigue life are greatly affected by the change of working clearance. Therefore, the analytical calculation model in this paper not only meets the dynamic characteristics analysis of ball bearing under different operation conditions, but also has great significance for the design and use of bearing.

Research on the Power Loss of High-Speed and High-Load Ball Bearing for Cryogenic Turbopump

This paper studies the lubrication characteristics of ball bearings for cryogenic turbopumps. First, the frictional coefficients between 440C and a Ag coating, 440C and solid PTFE (polytetrafluoroethylene), and 440C and a PTFE coating in LN2 (liquid nitrogen) are obtained using a ball-on-disk testing machine under a high sliding speed in the range of 0 to 8 m/s and a high contact stress in the range of 2.5 to 3.5 GPa. Dynamic and power loss models of high-speed and high-load ball bearings are established to study the key factors affecting the heat generation characteristics. In order to verify the correctness of these two theoretical models, a coupled fluid-thermal finite element model is built to evaluate the temperatures of the outer ring under different bearing speeds, which are then proved by experiments with ball bearings for cryogenic turbopumps. The results show that the power loss due to the spinning-sliding of the ball and the churning and drag of LN2 account for more than 80% of the total power loss; the spin-roll ratio of the ball on the inner raceway is a key indicator for this type of ball bearing, and the relatively small radial clearance and contact angle are suggested. Both of the proposed theoretical models have sufficient accuracy and can be used in the performance evaluation and optimization design of bearings.

Fault dynamic model of high-speed rolling bearing by a compound displacement excitation function considering the effect of defect roughness

Most of bearing fault dynamic models use simple displacement excitation functions to characterize the fault excitations from defects, and do not consider the influence of high-speed, dynamic radial clearance and transmission path, which brings the simulation signal a big gap with the measured signal. To solve these issues, this paper proposes a compound displacement excitation function by considering the influence of defect roughness, then constructs a new fault dynamic model of high-speed angular contact ball bearing (ACBB) by using the proposed displacement excitation function and introducing the effects of high-speed, dynamic radial clearance and transmission path. The proposed ACBB fault dynamic model is numerically solved for obtaining the dynamic responses under different fault sizes and speeds, then their characteristics in time and frequency domains are analyzed. The comparative results indicate that the simulation signals generated by the proposed model are closer to the measured signals, compared with those obtained by the typical bearing fault dynamic models. Finally, the correctness and superiority of the proposed model are verified by the experiments on faulty high-speed ACBBs.

A new approach for analyzing internal load and fatigue life of deep groove ball bearing in high-speed gearbox system

The study of the bearing fatigue life in high-speed gearboxes is an integral part of high-speed gear transmission research. There is still a lack of research on the analysis and calculating the bearing internal dynamic load and fatigue life considering gear engagement and centrifugal force simultaneously. Therefore, the paper proposes a new approach to acquire the internal load and fatigue life of the deep groove ball bearing in a high-speed gearbox system. Firstly, the modeling method of the gear mesh, flexible shaft, high-speed deep groove ball bearing, and housing is established, constructing the gearbox system dynamic model, which has the ability to calculate the bearing internal load. Then, the calculation method for analyzing the fatigue life of bearings is given based on the linear damage theory. The results show that the gear engagement and centrifugal force have meaningful effects on bearing internal loads and fatigue life, especially at high speeds. Both of them should be considered when evaluating the bearing life. The calculation method and model proposed in this paper provide a new technical approach for service performance evaluation and reliability design of high-speed deep groove ball bearing.

Simulation sudden oil supply in starved high-speed angular contact ball bearing

Many high-speed angular contact ball bearings work without sufficient lubrication in the contact area. A dynamic model including starved thermo-elastohydrodynamic lubrication (TEHL) was proposed to investigate starved ball bearings. For the bearings subjected to axial and radial loads, the inlet film thickness suddenly increases, the friction coefficient drops rapidly, and the ball skids severely as it passes through the low load region. When the location of the change occurs in the low load region, the degree of skidding is significantly reduced. Furthermore, the outer contact zone mainly determines whether or not to skid. Therefore starved high-speed bearings need to avoid a sudden increase in the inlet film thickness in the outer contact zone.

Dynamic characteristics of elastic ring squeeze film damper coupled high-speed ball bearings

This paper explores an elastic ring squeeze film damper (ERSFD) model incorporating high-speed ball bearings to study the journal dynamics at different rotor operating speeds and squirrel cage stiffness. Firstly, dynamic model of the ERSFD is established. The journal works under ball-outer raceway excitation rather than rotor unbalance force. Bearing high-speed characteristics including ball centrifugal force, contact angle change and heavy thrust-applied load are outlined in quasi-static model when deriving bearing force. Oil film pressure is governed by the Reynolds equation and solved iteratively using the central finite difference scheme. Flow performance through the orifice and its effect on the oil film pressure are analyzed using computational fluid dynamics (CFD) technique. Elastic ring deformation is addressed using a thin-walled ring model. Secondly, squirrel cage stiffness and rotor operating speeds were chosen as influence parameters to numerically examine the journal steady-state and transient dynamics, and finally the center orbit and vibration of the journal were experimentally measured. The results demonstrate that an increase in squirrel cage stiffness enables the journal to orbit at small size but leads to higher transmissibility. Small squirrel cage stiffness and rotor operating speed result in high amplitude and velocity oscillations and destabilize the journal; alternatively, higher squirrel cage stiffness is ineffective in transmissibility attenuation regardless of rotor operating speed. It was concluded that a small squirrel cage stiffness cooperating with high rotor operating speed contributes to stabilize journal and attenuate vibration effectively.