Angular Contact Bearings Research Articles

Retraction Note: Adaptive artificial intelligence for automatic identification of defect in the angular contact bearing

Retraction Note: Adaptive artificial intelligence for automatic identification of defect in the angular contact bearing

Fatigue spalling fault evolution analysis of an angular contact bearing of aeroengines

Fatigue spalling fault evolution analysis of an angular contact bearing of aeroengines

Study of the dependence of the natural frequencies of a rotor system with a vertically positioned rotor on the preload

The article discusses the possibility of using a method for determining the preload force for trust and radial bearings of spindle assemblies for high-speed milling. Previously, a method was developed and tested for determining the preload force of bearing supports on high-speed grinding electrospindles with a horizontal spindle.
 The object of study is a support with angular contact bearings 7004 ACD_P4A SKF and a vertical rotor. An information-measuring system has been developed, which consists of PCB 352C34 vibration acceleration sensors, a Vishay 614 force sensor, an NI-cRIO-9056 controller, NI 9250, NI 9237 and NI 9481 modules, and software written in the National Instruments Labview language.
 The system of test actions has been improved due to its automation. Test effects began to be carried out using a solenoid with a core, which was controlled by an NI controller and developed software. Due to this, the same time delay was formed between the test action and the start of recording the vibration acceleration signal.
 Vibration acceleration signals are obtained for the entire preload range. To study the controllability of the unit, two vibration acceleration sensors were used: with a parallel and perpendicular arrangement of the axes of the direction of vibration and test action. For the first and second groups of vibration accelerations, spectral transformations were carried out, and the amplitude-frequency characteristics of the assembly were obtained for the entire range of preload values.
 As a result of the work, it was concluded that the presented methodology and criteria are applicable to high-speed milling spindle assemblies with a vertical rotor. It is also shown that this technique can be automated.

EFFECT OF SPRING STACKING STIFFNESS ON AXIAL FORCE AND DISPLACEMENTS OF ANGULAR CONTACT SPINDLE BEARINGS

Machine accuracy of workpiece is dependent on a number of factors including the machine spindle nose position. Recently, the application of thermal phenomenon especially in electrospindle has been of great interest. Thermal displacement of the spindle nose affects the accuracy of machining and it also depends largely on the amount of power loss in the bearings. This paper presents the angular contact bearing model which takes into account the stiffness of spring stacking. The result show what effect does the stiffness of the spring stacking have on axial force, contact forces and displacements of angular contact bearing. Moreover, omission in the analysis of the stiffness of the spring stacking result in errors in the estimation of the position on the spindle nose due to the deformation of the elastic spring.

Dynamic, thermal, and vibrational analysis of ball bearings with over-skidding behavior

The term “over-skidding” indicates that the cage rotational speed ratio exceeds the theoretical value as ball purely rolls on the raceway. Different from the skidding phenomenon that occurs in low-load and high-speed bearing, over-skidding usually occurs in large-size angular contact bearings, and it is still difficult to suppress under high load conditions. The main forms of damage to the raceway by over-skidding are spinning and gyro slip. To further explore the vibration characteristics and thermal effects of this phenomenon, a set of over-skidding tests of an angular contact bearing with a bore diameter of 220 mm were conducted on an industrial-size test bench. Through the experiment, the influence of axial load, rotational speed, and lubrication conditions on the occurrence of over-skidding were determined. Based on a previous dynamics model, the heat generation and thermal network models were integrated in the present study to predict the over-skidding and its thermal behavior. The model was validated in terms of the measured degree of over-skidding and temperature rise. The results showed that the degree of over-skidding reaches up to 12% of the theoretical value, and the friction power loss of the ball-pocket accounts for 30% of the total power loss. The analysis of the vibration signal showed a strong correlation between the bearing vibration characteristics and over-skidding behavior, thereby providing a way to indirectly measure the degree of over-skidding.

Effect of Preload on the Vibrations of EHL Angular Contact Ball Bearings: Theoretical and Experimental Results

The vibrations of a shaft in rotary mechanical systems supported by angular contact ball bearings are investigated theoretically and experimentally for various preloads in this paper. In the theoretical part of the study, a dynamic bearing model is presented, a rigid shaft supported by EHL angular contact bearing has been modelled as 5 DoF. Non-linear equations of motion are solved numerically by the Runge–Kutta method. In the second part of the study, an experimental setup that enables performing different operating cases has been designed to validate the theoretical results. Theoretical and experimental data are investigated and compared in both time and frequency domains and the results are compared. It is observed from both the theoretical and experimental studies that preload has a significant effect on the vibration behaviour. Results show that the increase in preload reduces the amplitude of the variable compliance frequencies of bearing, the natural frequency of system is shifted to a higher value, and using signal processing with an envelope spectrum gives better results in spectral analysis; small deviations occur between the theoretical and the experimental data due to modulation and noise from machine elements such as gear, motor, misalignment, waviness, etc. Therefore, the presented dynamic bearing model can be used with a reasonable accuracy to examine effect of preload on the vibration of shaft-bearing system.

Interaction of anti‐wear additiveTCPwith advanced bearing steels

AbstractThe quest for high‐performance energy efficient aircraft turbine engines has led to the development of a number of high‐performance rolling element bearing materials and engine lubricants with the aim of providing superior mechanical component durability. The heat treatments/surface treatments used to achieve the desired physical and mechanical properties for these newer alloys can result in altered surface chemistry from currently used materials. Surface chemistry plays an important role during lubricant‐bearing material interactions and the formation of beneficial tribological films during component operation. The objective of this study was to analyse the tribo‐films formed on bearing surfaces and investigate the interaction of lubricant additives, specifically the phosphorus‐based anti‐wear additive tricresyl phosphate (TCP), with different bearing materials under relevant bearing operating conditions. Bearing tests were conducted on 208‐size (40 mm bore) angular contact bearings at 127°C and 154°C using gas turbine engine lubricants conforming to MIL‐PRF‐23699G at maximum Hertzian contact stresses of 3.1 GPa and 3.55 GPa. Bearing materials evaluated included AISI M50, M50NiL, nitrided M50NiL (N) and three variants of Pyrowear 675 with silicon nitride rolling elements. Tribo‐films were analysed using Energy dispersive X‐ray spectroscopy and Auger Electron spectroscopy. Results indicate that phosphorus‐rich anti‐wear tribo‐films form on all of the bearing materials studied. The applied thrust load and heat treatment had a significant effect on tribo‐film thickness. The study also suggests that current gas turbine engine lubricants formulated with TCP should form beneficial tribo‐films that enhance bearing fatigue life and performance.

Modelling and Analysis of High-Speed Angular Contact Ball Bearing

Angular contact bearings are of primal importance in accommodating rotational mechanisms with high-speed characteristics. Their applications are centric to heavy axial and radial loads sustaining thrust loads to a single direction. In high-speed applications, factors such as centrifugal force, gyroscopic moments and relative displacements in various geometric features of the bearings are to be taken into consideration. This study focuses on establishing the contact angles, contact forces and spin speed for angular contact bearing to withstand varied rotational angular velocities. The forces experience a non-linear variation with respect to the body stiffness thus necessitating the involvement of numerical methods to converge at precise solutions through each juncture. The outer raceway of the bearing is accepted to be static with respect to the inner raceway as the input shaft for any application is predominantly affixed to the inner raceway of the angular contact bearing. Geometrical variations are determined under combined load conditions to simulate the natural working of the bearing at accelerated speeds. The analyses involve results for spatial parameters which are iteratively solved for each of the rolling elements in the bearing taken into concern. The spin speeds of the rolling elements are shown to dampen and exponentially increase with respect to their angular positions. The outputs manifested through this work can be utilized to accurately predict shift of salient design attributes of an angular contact bearings through low and high-speed applications.

Analysis of Dynamic Characteristics and Skidding State of Angular Contact Bearing by Thermo-hydro-elasto-dynamic Coupling Model

Analysis of Dynamic Characteristics and Skidding State of Angular Contact Bearing by Thermo-hydro-elasto-dynamic Coupling Model

Analysis of the dynamic characteristics of the cage of high-speed angular contact bearings under preloaded load

First, the law of motion of the bearing cage, inner ring, and ball are theoretically analyzed. Combining the nonlinear contact and deformation relationship between the various elements of the bearing, an explicit dynamic model of the high-speed angular contact bearing is established. Second, the stability and motion characteristics of the cage are analyzed from four aspects: the three-dimensional center of mass motion track of the cage with time, the deviation ratio of the center of mass vortex velocity, the angular velocity, and the linear velocity. The dynamic characteristics of the cage during the start-up phase of unsteady operation have been emphatically studied. The research results show that during the start-up phase, the greater the preload, the later the circle of the center of mass motion track of the cage expands outward, and the better the stability. The higher the rotation speed, the earlier the vortex trajectory circle of the center of mass of the cage expands outward, and the motion stability first strengthens and then weakens. Finally, the simulated value of the linear velocity of each bearing element changes with time are compared with the theoretical value, the correctness of the established explicit dynamic model was verified.

Experimental and theoretical approaches for determining cage motion dynamic characteristics of angular contact ball bearings considering whirling and overall skidding behaviors

Cage stability is an essential indicator of the guaranteed efficiency and reliability of the rolling element bearing. Moreover, cage instability can greatly shorten the bearing’s service life. The whirl characteristics of the cage caused by ball–cage collisions are closely related to the overall bearing skidding degree. To explore the stability and skidding characteristics of self-lubricated cages used in spacecraft angular contact bearings, a comprehensive bearing dynamic model focused on cage characteristics is proposed. The cage was divided into Nb (number of balls) segments owing to the low stiffness of the cage material (porous polyimide). The model comprised ball self-rotating and revolution motions with 4*Nb degrees of freedom (DOF) and cage motions with Nb + 3 DOF. In the latter, 3 represents the cage whirling motion in the translational and axial directions. The ball-pocket normal and tangential forces, ball-pocket axial collisions, the ball-raceway traction force and moment, imbalances, centrifugal force, and thin oil film lubrication are included in the model. A test bench for exploring the cage motion with a high-speed camera to capture cage images was developed. Three experimental case studies investigating the effects of operating speed and applied load validated the effectiveness and accuracy of the model. Several indicators describing cage stability and cage skidding degree were proposed based on the experimental and theoretical results. It was found that the rate of increase of the whirl radius reduced with a linear increase in the rotation speed. The whirling radius displayed an approximate hyperbolic downward trend with increasing axial force. The skidding results suggested that applying a large axial load to the bearing may have been counterproductive in preventing bearing skidding. In addition, the cage was prone to instability as the radial load increased owing to intensive cage-guide ring rubbing.

Recent Patents on the Angular Contact Ball Bearing of High-Speed Motorized Spindle

Background:: Angular contact ball bearings are the most popular bearing type used in the high speed spindle for machining centers, The performance of the bearing directly affects the machining efficiency of the machine tool, Obtaining a higher value is the direction of its research and development. Objective:: By analyzing the research achievements and patents of electric spindle angular contact bearings, summarizing the development trend provides a reference for the development of electric spindle bearings. Methods:: Through the analysis of the relevant technology of the electric spindle angular contact ball bearing, the advantages and disadvantages of the angular contact ball bearing are introduced, and the research results are combined with the patent analysis. Results:: With the rapid development of high-speed cutting and numerical control technology and the needs of practical applications, the spindle requires higher and higher speeds for bearings. In order to meet the requirements of use, it is necessary to improve the bearing performance by optimizing the structure size and improving the lubrication conditions. Meanwhile, reasonable processing and assembly methods will also have a beneficial effect on bearing performance. Conclusion:: With the continuous deepening of bearing technology research and the use of new structures and ceramic materials has made the bearing's limit speed repeatedly reach new highs. The future development trend of high-speed bearings for electric spindles is environmental protection, intelligence, high speed, high precision and long life.

Experimental investigation on time-domain features in the diagnosis of rolling element bearings by acoustic emission

Inspired by previous achievements, different time-domain features for diagnosis of rolling element bearings are investigated in this study. An experimental test rig is prepared for condition monitoring of angular contact bearing by using an acoustic emission sensor for this purpose. The acoustic emission signals are acquired from defective bearing, and the sensor takes signals from defects on the inner or outer race of the bearing. By studying the literature works, different domains of features are classified, and the most common time-domain features are selected for condition monitoring. The considered features are calculated for obtained signals with different loadings, speeds, and sizes of defects on the inner and outer race of the bearing. Our results indicate that the clearance, sixth central moment, impulse, kurtosis, and crest factors are appropriate features for diagnosis purposes. Moreover, our results show that the clearance factor for small defects and sixth central moment for large defects are promising for defect diagnosis on rolling element bearings.

Research and optimization of axial gas forces in turbines of turbojet bypass engines with afterburner combustion chamber

The paper presents the results of research and analysis of the efficiency of the power systems of the rotor of the gas generator of modern bypass engines with an afterburner. It was revealed that the gas axial forces, which are the difference between the axial forces of the rotors of the high-pressure compressor and its turbine, acting on the front angular contact bearing of the gas generator, can be significantly reduced in order to increase their reliability and service life.

Study on Simplified Model and Numerical Solution of High-Speed Angular Contact Ball Bearing

For the calculation model of high-speed angular contact bearing has many variables, the large root difference exists, and the Newton iterative method solving the convergence depends on the initial value problems; thus, the simplified calculation model is proposed and the algorithm is improved. Firstly, based on the nonlinear equations of variables recurrence method of the high-speed angular contact ball bearing calculation model, it is proved that the ultimate fundamental variables of calculation model are the actual inner and outer contact angles, the axial and radial deformations. According to this reason, the nonlinear equations are deformed and deduced, and the number of equations is reduced from 4Z + 2 to 2Z + 2 (Z represents the number of rolling bodies); a simplified calculation model is formed. Secondly, according to the small dependence of the artificial bee colony algorithm on the initial value, an improved artificial bee colony algorithm is proposed for the large root difference characteristics of high-speed ball bearings. The validity of the improved algorithm is verified by standard test function. The algorithm is used to solve the high-speed angular contact ball bearing calculation model. Finally, the deformations of high-speed angular contact ball bearings are compared and verified by experiments, and the results of improved algorithm show good agreement with the experiments results.

Experimental Investigation of the Diagnosis of Angular Contact Ball Bearings Using Acoustic Emission Method and Empirical Mode Decomposition

Early detection of angular contact bearings, one of the important subsets of rolling element bearings (REBs), is critical for applications of high accuracy and high speed performance. In this study, acoustic emission (AE) method was applied to an experimental case with defects on angular contact bearing. AE signals were collected by AE sensors in different operating conditions. Signal to noise ratio (SNR) was calculated by kurtosis to entropy ratio (KER), then acquired signals were denoised by empirical mode decomposition (EMD) method, and optimal intrinsic mode function (IMF) was selected by the proposed method. Finally, envelope spectrum was applied to the denoised signals, and frequencies of defects were obtained in different rotating speeds, loadings, and defect sizes. For the first time, a small defect with width of 0.3 mm and loading of 475 N was detected in early stage of 0.04 KHz. Moreover, a comparison between theoretical and extracted defect frequencies suggested that our method successfully detected localized defects in both inner and outer race. Our results show promise in detecting small size defects in REBs.

Minimum Energy Hypothesis in Quasi-Static Equilibrium Solutions for Angular Contact Ball Bearings

The commonly used quasi-static model for angular contact bearings is enhanced by coupling contact mechanics and bearing kinematic analyses with traction or friction behavior in ball–race contacts. The points of pure rolling in the contacts, which constitute the primary inputs in the kinematic equations, are determined by minimizing the frictional dissipation based on a prescribed elastohydrodynamic traction model. Such an intricate coupling between contact mechanics, bearing kinematics, and lubricant behavior provides significant enhancement of simple quasi-static model for greatly improved prediction of traction behavior and heat generation in ball bearing contacts. The predictions are in close agreement with those obtained by much more sophisticated dynamic analysis based on integration of classical differential equations of motion of bearing elements. The enhanced quasi-static model can therefore be effectively used as a design tool for optimizing thermal dissipation in ball–race contacts in ball bearings. To facilitate immediate evaluation and implementation of the model to practical problems, a standalone software, containing the enhanced quasi-static model, is made freely available at www.PradeepKGuptaInc.com/AdoreQS.html.

Dynamic characteristics of drilling spindle supported by radial permanent magnet bearings

This paper presents the drilling spindle dynamic and harmonic characteristics supported by radial permanent magnet bearings (PMBs).Initially, multi-ring radial PMB is designed in proportionate to the dimensions of drilling spindle using Coulombain model and vector approach. Dynamic analysis of spindle is carried out for three different combinations between conventional angular contact bearings (ACBs) and PMBs. First, the spindle was supported by only ACBs. Second, ACBs were completely replaced by radial PMBs and one ACB was used in between two PMBs making it as a hybrid bearing set (HBS) in the last case. The effect of bearing preload, bearing span and cutting force on the spindle natural frequency, harmonic frequency and critical speed of drilling spindle system was investigated through rotor dynamic analysis. This analysis focuses on the feasibility of successful usage of HBS in drilling machine spindles with higher critical speeds and maximum amplitudes produced due to chattered vibrations and tangential cutting forces.

Stress Analysis and Safety Factor of Shaft on Pepper Peeler Machine to Reduce Environmental Pollution

Manually, pepper peeling uses water flowing in the river for 8-14 days that cause the river to become polluted by pepper peel and cause a bad smell. A pepper peeling machine is a tool to peeling pepper that has a system using two dishes consisting of a fixed top dish and a rotating bottom dish. A shaft is used to rotate the bottom dish with 14.58 rpm rotation, and it requires 1 kW electric motor with 1400 rpm rotation that is transmitted by reducer ratio of 23.3:1 and a bevel gear ratio of 1.6: 1. The shaft must be analyzed to determine its ability where the material is carbon steel material that has yield strength 350 MPa and is supported by two angular contact bearings which function as pin constraints and frictionless constraints. The shaft was analyzed using stress analysis with static analysis method using Autodesk Inventor Version 2019 software. Based on the analysis results, a minimum von mises stress of the shaft is 0.00 MPa and a maximum of 826.57 MPa on the diameter of 25 mm, minimum safety factors of 0.42 on the diameter of 25 mm and a maximum of 15. In Von-Mises stress and safety factor, the diameter of a shaft is not strong enough to withstand the load. To be able to meet the determined yield strength with a minimum safety factor of 1, the minimum diameter needed is 34.05 mm with a safety factor of 1.1. Using this machine, pepper peeling that done in the river can reduce river pollution.

An extended contact model of the angular bearing

The article presents a new contact model of an angular bearing, called the extended model. The model takes account of the effects of centrifugal load caused by thr rotating ring of the bearing and the issue of elasticity. Present models, encountered in literature and referred to in the article as classical, consider the centrifugal force caused by the rotating ball only. Results of analytical research on the extended model and of FEM simulation show explicitly that the contact angles of bearings, and thus contact loads, differ very much from those values obtained in the classical model. These differences are disadvantageous for designing bearing assemblies, since contact loads are greater than those obtained in the classical model. This means, among others, that the present structures with angular contact bearings are in reality subject to greater loads than the constructor has envisaged. The motto of the article is to design analytical calculation models in such a form which would enable the constructor to estimate contact loads, just using a standard scientific calculator or MS Excel type applications; so that there would be no need for solving complex models using numerical methods.