High-speed Roller Bearings Research Articles

An accurate measurement method for center oil film thickness in high-speed roller bearing using ultrasound

A multicycle focal spot mapping method is proposed to design the specific pulse emission frequency and the recorded pulse number. A great number of successive ultrasonic pulses with a specific emission frequency are utilized to examine the lubricant film in the roller bearing so that at least one ultrasonic pulse will interrogate the center of the contact region. Subsequently, the center oil film thickness is calculated by the selected minimum ultrasonic reflection coefficient amplitude. A statistical test analysis and an experimental analysis are performed to validate the proposed method. The results show that the proposed method can be used to accurately measure the center oil film thickness in high-speed roller bearings, which overcomes the speed limitation of the existing method.

High-speed rolling bearing lubrication reliability analysis based on probability box model

An efficient and high-precision method is proposed for the analysis and evaluation of high-speed rolling bearing lubrication reliability based on a probability box (p-box) model. This method expands the application of mixed aleatory and epistemic uncertainties analysis within the realm of bearing lubrication reliability. Initially, the method establishes a reliability model for high-speed rolling bearing lubrication, taking into account the shear thermal effect through the analytical solution of a Γубин-type entrance zone. Subsequently, the uncertainty surrounding lubrication parameters under high-speed conditions is examined, with its mixed aleatory and epistemic uncertainties accurately depicted by using the p-box model. Furthermore, an effective and precise method for analyzing the reliability of rolling bearing lubrication is introduced based on the p-box model, in which the optimization model involved is efficiently solved using a decoupling method. Finally, lubrication reliability analysis and sensitivity analysis of parameter uncertainty levels are conducted for high-speed rolling bearings in this study. The research results demonstrate that the proposed method achieves higher accuracy and efficiency.

Design and Testing of a Measurement Device for High-Speed Bearing Evaluation

The submitted article focuses on the proposal of a testing device for researching alternative methods of lubricating technical systems, specifically high-speed rolling bearings using lubricants containing nanoparticles. The aim of this research is to verify the functionality of the proposed technical device, whose main task is to ensure the measurement of the functional and operational characteristics of high-speed rolling bearings. The proposed technical device allows us to carry out a series of measurements, primarily for the purpose of selecting specific bearings and secondarily for the purpose of conducting technical diagnostic measurements. The results of these measurements are significant in the selection of suitable nano-particle additives for the lubrication of the tested bearings. The tests was carried out using speeds reaching 110,000 rpm. Methods of monitoring vibrational and acoustic diagnostics were chosen for the analysis of the operational processes of loaded technical systems.

Ultrasonic measurement of roller revolution speed for high-speed rolling bearing

The sliding state of the bearing rollers can be identified by measuring the roller revolution speed. At present, the roller revolution speed is mainly approximated by the average speed of the cage, which can be obtained by optical and electric methods. However, there are some bottlenecks in the practical application of these methods. In this study, a non-destructive ultrasonic technique is proposed to measure the high-speed rolling bearings' roller revolution speed. In order to reduce the impact of time-domain noise on the ultrasonic echo pulse signal, autocorrelation analysis and the FFT transform are introduced. The passing frequency of a roller can be more accurately calculated by using the CZT (linear frequency modulation Z transform) spectrum thinning algorithm. This ultrasonic approach's validity is confirmed when compared to the conventional optical method at low speed. Then, in accordance with the theoretical models, the roller slippage at high speed is observed by directly measuring the speed of the roller revolution.

Effect of clearance on the dynamic characteristics of high-speed rolling bearings with multiple defects

Clearance is a pivotal factor in determining the fatigue life of high-speed rolling bearings (HSRBs). As HSRBs naturally experience various defects, their clearance levels tend to rise. However, a clear understanding of the vibration caused by clearance is still lacking. To address this gap, a five-degree-of-freedom dynamics model for HSRBs is proposed. This model accounts for centrifugal force, gyroscopic moment, and time-varying contact angle. In addition, the proposed model incorporates asymptotic theory to describe the defect process and the time-varying contact force derived from the Hertzian point contact theory between rolling elements and raceways. Furthermore, the model considers the variations in load zone and rolling element velocity that arise due to clearance. Applying this model, the dynamic response of HSRBs with different level clearances is calculated. The model's correctness is verified by comparing the dynamic response with the finite element model results and data measured using a test rig built for aero-engine spindle bearing. The results demonstrate that the extent of the load zone shrinks as the clearance increases, although the reduction rate gradually slows down. Since the bearing is loaded only in the load zone, aggravated clearance causes rolling elements to slip in the non-load zone. The effect of clearance on contact force is significantly weaker pronounced than that of defects. These research findings provide a theoretical foundation for the analysis and performance prediction of HSRBs and have important reference values for their optimal design.

The Friction of Radially Loaded Hybrid Spindle Bearings under High Speeds

Friction losses are an important parameter for evaluating the operational behaviour of high-speed rolling bearings. Specifically, in machine tool applications, the bearings are subjected to high radial loads and high speeds, which lead to increased forces in the rolling contact and, as a result, increased bearing friction. In this high-speed application, hybrid spindle bearings, typically made of ceramic balls and steel raceways, show better frictional behaviour compared to full steel-made bearings. Therefore, precise knowledge of the friction characteristics of high-speed hybrid bearings can improve friction models and generalise them to spindle bearings with different types, geometries, and operating conditions. In this article, a new straightforward and cost-efficient method for measuring the frictional torque in spindle bearings is presented. A rigidly arranged 7008 hybrid spindle bearing pair was tested up to rotational speeds of 24,000 rpm and high radial loads of 3 kN. The effects of oil–air and grease lubrication are discussed in characteristic diagrams of the tested bearings. Then, based on the test results, a friction calculation model is presented and validated for the outer race control and minimised power dissipation regarding the influence of radial forces.

Fault Diagnostics and Faulty Pattern Analysis of High-Speed Roller Bearings Using Deep Convolutional Neural Network

Abstract In this article, vibration-based fault diagnostics and response classification have been done for defective high-speed cylindrical bearing operating under unbalance rotor conditions. An experimental study has been performed to capture the vibration signature of faulty bearings in the time domain and for different speeds of the unbalanced rotor. Two-dimensional phase trajectories are generated by estimating the time delay and embedding dimension corresponding to vibration signatures. Qualitative analysis involves the implementation of a deep convolutional neural network (DCNN) utilizing the phase portraits as input to classify the nonlinear vibration responses. Comparison with the state-of-art classifiers such as artificial neural network (ANN), deep neural network (DNN), and k-nearest neighbor (KNN) is presented based on classification accuracy values. Thus, the values obtained are 61%, 67%, 72%, and 99% for ANN, DNN, KNN, and DCNN, respectively. Hence, the proposed intelligent classification model accurately identifies the dynamic behavior of bearing under unbalanced rotor conditions.

Analysis of Circulation Characteristics and Heat Balance of High-Speed Rolling Bearing under Oil-Air Lubrication

Aiming to solve the problem of oil-air lubrication failure caused by the high working temperature of high-speed rolling bearings, this study proposes a method, based on the theory of gas-solid two-phase flow and bearing tribology, of predicting the dynamic temperature rise of nonlinear high-speed rolling bearings under oil-air lubrication conditions. The accuracy of the fluid–structure coupling model is verified by comparing the temperature rise test results of angular contact ball bearing at different speeds. The characteristics of oil-air lubrication circulation and the relationship between the lubrication parameters and the heat balance of the high-speed rolling bearings have been studied. The results show that the gas supply pressure of the system has a significant influence on the continuity and fluctuation of the oil film in the oil pipe nozzle. The initial rise in temperature of the inner and outer rings of the bearing and the fluid domain has a speed threshold value, and the temperature increases linearly with the bearing speed. With the increase in the oil supply and lube oil viscosity of the system, the temperature rise of the outer ring of the bearing increases first, then decreases, and finally increases again. There is an optimal oil supply 5.5 mL and optimize viscosity 68 cSt for the bearing in the work condition.

Research on Anti-Wear Properties of Nano-Lubricated High-Speed Rolling Bearings under Various Working Conditions

Research on Anti-Wear Properties of Nano-Lubricated High-Speed Rolling Bearings under Various Working Conditions

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.

Tribological Characteristics of Nano-Lubricated High-Speed Rolling Bearings Considering Interaction between Nanoparticles and Rough Surface

The embedding situation between various nanoparticles and rough surfaces affects the lubrication characteristics of rolling bearings. If not properly handled, this can easily lead to wear damage of rolling bearings. Therefore, the friction and wear mechanism of nano-lubricated high-speed rolling bearings under various nanoparticle embedded states is studied in this manuscript. Mixed oils containing different sized SiO2 nanoparticles and dispersants are prepared, and then the tribology test of nano-lubricated high-speed rolling bearings considering the interaction between various nanoparticles and the rough surfaces is conducted. The friction and wear properties such as coefficient of friction, wear volume and real-time temperature rise of high-speed rolling bearings under different embedding conditions are revealed, and the anti-wear mechanism of the nano-lubricated high-speed rolling bearings is obtained. The results show that compared to the complete non-embedded state, the complete embedded state of different nanoparticles effectively improves the anti-wear effect of the bearing. When the nanoparticle mixed oil is added, the bearing still has good anti-wear performance under the conditions of high speed and lack of oil. As for the light loaded rolling bearing adopted with nano-mixed oil, the coefficient of friction is appropriately increased, as well as the skid reduced, while the wear of the rolling bearing is effectively reduced. This research will provide theoretical basis and important reference for nano-lubrication and its application in aviation rolling bearings.

Investigation of Oil–Air Flow and Temperature for High-Speed Ball Bearings by Combining Nonlinear Dynamic and Computational Fluid Dynamics Models

Abstract An improved nonlinear dynamic model of high-speed ball bearings with elastohydrodynamic lubrication is adopted to predict the movements of balls and power loss of ball bearings for defining the boundary conditions of a computational fluid dynamics (CFD) model. Then, this method of combining nonlinear dynamic and CFD models is 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.

Data Augmentation and Characterization of Nonlinear Vibration Responses of High-Speed Rolling Bearing

Data Augmentation and Characterization of Nonlinear Vibration Responses of High-Speed Rolling Bearing

Simulation of an Air–Oil Mixture Flowing in the Internal Cavities of a High-Speed Rolling Bearing

A mathematical model of the flow of a lubricant in the internal cavities of a rolling bearing under the conditions of forced lubrication with the use of an oil–air mixture is considered. The computational domain contains movable boundaries that make it possible to take into account the motion of the rolling elements and the retainer. By using the methods of computational flow dynamics, the turbulent flow parameters for an oil–air mixture are calculated, and the frictional power loss in the bearing are estimated. The hydrodynamic forces and moments that act on the bearing parts are calculated based on the distribution of pressure and friction stress at the boundaries thereof.

Tribo-dynamic analysis of high-speed roller bearings for electrified vehicle powertrains

Roller bearings are critical components in electrified powertrains. At high speeds, the critical role of the elastohydrodynamic lubrication (EHL) cannot be ignored, necessitating a tribo-dynamic analysis. This paper investigates the behaviour of roller bearings under operating conditions present in high-speed electrified powertrains. The bearing motion is obtained experimentally using a novel experimental rig. The bearing centre's orbital motion is acquired from the experiment and used as the boundary condition for tribological analysis. Results reveal that the EHL film thickness increases from 0.2 to 1.9 μm across a speed range of 0–15 000 rpm. A comparison with conventional dry contact analysis shows that roller load can be underestimated if the lubricant film is neglected in the roller-race contact deformation.

Validation and application of a numerical approach for the estimation of drag and churning losses in high speed roller bearings

A numerical-based model is proposed to estimate drag and churning losses in high speed roller bearings, which is caused by the rotation and translation of the rollers in the fluid environment inside the bearing. Three existing models for the total hydraulic loss prediction are used to validate the numerical approach, including the SKF model, the Palmgren model, and the Parker model. After that, the validated model is employed to analyze drag and churning losses of counter-rotating roller bearings, having obvious advantage over the other three models. Results show that the numerical model is close to the Parker model and partly similar with the SKF model if the supply of the lubricant oil is sufficient. And the estimated result by the Palmgren model is always the lowest. For the counter-rotating roller bearing, it is demonstrated that the drag and churning losses are rather serious due to its two rings rotating together, and they are related to the bearing supporting design. This is of importance for the intershaft supporting application in turbine engine where precise lubricating system design is a big challenge.

Existence of a Tunnelling Component of Electrical Drift Current through a DielectricFilm in High Frequency Knots with a Liquid and BoundaryFriction

In particular functioning of high-speed rolling bearings with use of lubricant with rather big viscosity can happen without destructions of a high-resistance lubricant film. At the same time the annex of tribovoltage to rolling bearings leads to emergence of electric current caused in particular by tunneling effect of a charge across a film. Control of technical condition of frictional units has to be exercised according to electric parameters of the lubricant film which is implemented in friction zones. Values of these parameters depend on a condition of a lubricant film, and in particular on her temperature which is caused by degree of wear of details of frictional units which function under the influence of mechanical tension. The model can be used for technical diagnostics, and also for decrease of speed of process of wear. In practice the developed model can be used for those productions, vehicles, control systems where failure of frictional pieces can lead to failure of an expensive production inventory, the emergency cessation of production of goods, accidents of means of transportation of goods and people, loss of management of technical systems and also control systems of human activity.

Study on the Thermal Distribution Characteristics of High-Speed and Light-Load Rolling Bearing Considering Skidding

Skidding, which frequently occurs in high-speed rolling bearings, has a significant effect on the thermal distribution and service reliability of the bearings. An improved theoretical model of friction power loss distribution in high-speed and light-load rolling bearings (HSLLRBs) considering skidding is established, and the effects of various operating parameters on the friction power loss are investigated. The results show that the friction power loss of the inner ring and outer ring as well as the total friction power loss of the bearing increase as the slip ratio increases, but that the friction power loss of the cage guide surface and roller oil churning show a reverse trend. In addition, the increase in inner ring speed and kinematic viscosity leads to an increase in bearing friction power loss. The steady and transient temperature field distribution of HSLLRBs is obtained by the finite element method (FEM), and the results show that the inner ring raceway has the highest temperature, whereas the cage has the lowest. The temperature distribution test rig of a full-size roller bearing is constructed, and the influence mechanism of the slip ratio, rotation speed, load, lubrication, and surface topography on the bearing temperature distribution are obtained. The experimental results are consistent with the theoretical results, which also validates the theoretical method.

Numerical investigations on drag coefficient of circular cylinder with two free ends in roller bearings

Abstract In high speed roller bearings, the drag force due to the oil-air mixture present in the bearing cavity – that is acting against the roller movement – is usually computed with a two-dimensional model of flow around a cylinder of infinite length. However rollers are of finite length, and the flow is perturbed by the two free ends, the surrounding rings, the cage and other rolling elements. In this article, the Computational Fluid Dynamics (CFD) method is employed to analyze first the flow around one finite-length circular cylinder with two free ends in an open space. Then the model is changed to one finite cylinder and then several in-line circular cylinders sandwiched by two flat walls, which represents a simplified approach. The results indicate that both the flow pattern around the cylinder and its drag coefficient are modified in comparison with the two-dimensional model. Finally a relationship between the drag coefficient and the Reynolds number suitable for circular cylinder in roller bearings is proposed.

Bubble Flow Analysis of High Speed Cylindrical Roller Bearing under Fluid-Solid Thermal Coupling

Heat generation model of high speed cylindrical roller bearing is constructed by calculating the local friction in the bearing. Bubble flow calculation model of roller bearing considering fluid-solid thermal coupling is constructed based on two-body fluid model and k-ε turbulent model, in which diameter and size of bubbles, breakup, and coalescence model of bubbles are considered. Using dynamic mesh method, a new method for evaluating bearing temperature is set up treating the rolling elements as moving heat sources. Based on these models and finite element method, bubble flow of a high speed roller bearing is studied based on FLUENT software. The numerical study reveals the relationship between velocity of bearing, air volume fraction, and velocity and pressure of oil-air flow. An increase of air content in the oil produces a lower pressure at the bearing outlet while the exit fluid velocity increases. When fluid-solid thermal coupling effect is considered, velocity and pressure at outlet of the bearing both become larger, while temperature of bearing is lower than that without coupling. In comparison, the coupling effects on flow pressure and temperature are obvious. For a given rotating speed, there is an optimal value for air volume fraction, such that temperature rise of the bearing reaches the lowest value. Experiments verify the outcomes of the method presented in this paper.