Angular Ball Research Articles

Research on Multi-Directional Spalling Evolution Analysis Method for Angular Ball Bearing

The prediction of spalling failure evolution in the lifespan of aeroengine bearings is crucial for en-suring the safe return of aircrafts after such failures occur. This study examines the spalling failure evolution process in bearings by integrating the proposed spalling region contact stress analysis model with the multi-directional subsurface crack extension analysis model. The results elucidate the general pattern of spalling expansion. Utilizing this methodology, the fatigue spalling fault evolution in bearings is thoroughly analyzed. Additionally, a two-dimensional model has been developed to simulate and analyze crack propagation in the critical direction of the spalling region, significantly enhancing the model’s computational efficiency.

Analysis of high-speed angular ball bearing lubrication based on bi-directional fluid-solid coupling

Analysis of high-speed angular ball bearing lubrication based on bi-directional fluid-solid coupling

A contact analysis for unconventional mounting processes of angular ball bearings

AbstractRigorous protocols must be followed when mounting ball bearings to avoid structural damage and subsequent malfunctioning or unexpected failures. Unconventional mounting procedures may produce excessive contact pressures between the elements of the bearing, therefore the whole process must be well-understood and modelled to prevent unwanted effects. Specifically for angular ball bearings, fitting axial forces should always be applied over the raceway subjected to the shrink-fit to avoid contact forces arising on the ball. In the present study, such an axial force is applied unconventionally, such that the axial force is transferred to the shrink-fit raceway through the balls. In this scenario, the evaluation of the contact areas and the pressure distributions is accomplished by exploiting both analytical and FEM approaches, supported by bespoke experimental tests to determine the relevant frictional coefficients and mounting forces. The study demonstrated how analytical methods can successfully replace more demanding FEM-based tools for the evaluation of the bearing mounting force and contact pressure and extent. FEM modelling can, however, be more accurate when dealing with more generic boundary conditions and more intricate geometrical features involved.

Measurement for Lubricant Distribution in an Angular Contact Ball Bearing and Its Influence Investigation

Oil lubrication is widely adopted in rolling bearings, the characteristics of which affect the oil film formation and friction state, and also the heat generation and dissipation characteristics. However, it is difficult to measure the internal lubrication of rolling bearings in practice, which is of great importance for lubrication and structure design. In this work, one measurement system for lubricant distribution was built and installed on a test rig to obtain original pictures of the lubricant in bearings. Grayscale images were obtained by picture processing to characterize the lubricant distribution, and the image pixels were evaluated for the characterization of lubricant volume. Finally, the measurement of the lubricant distribution in the angular ball bearing was carried out under different lubrication and cage groove conditions, and their influences were investigated. The results show that the lubricant distribution is affected by the oil jet nozzle angle, operating speed, and cage structure. The lubricant capacity among balls and the cage pocket in bearings gradually increased with the increase in the nozzle angle and the depth of the cage grooves, but decreased with the increasing operating speed. The experimental results are helpful to provide a basis for the structure and lubrication design of ball bearings.

Grip position affects upper limb kinematic chain during tennis double-handed backhand topspin strokes: considerations for transitioning tennis grip position technique

ABSTRACT The purpose of this study was to compare the upper limb kinematic chain of tennis players using either an eastern or continental non-dominant grip position during the forward swing of the double-handed backhand stroke. Sixteen right-handed tennis players performed backhands using two non-dominant grip positions (eastern and continental), aiming for two cross-court zones (deep and short). Trajectory data were captured using sixty reflective markers attached to the upper limb and racket using a 12-camera Vicon motion capture system (250 Hz). Peak angular velocity was significantly greater for multiple joint rotations at the dominant shoulder and entire non-dominant limb in the eastern grip. Subsequently, greater peak racket head angular velocity and post-impact ball speed were generated by the eastern grip, while shot accuracy was similar between grip types. There was delayed dominant shoulder peak adduction angular velocity for the continental grip, possibly due to a lack of skill familiarity causing changes in coordinative patterns. Collectively, the non-dominant grip position appears to influence proximal and distal upper limb movement. Future research should explore upper limb segment coordination comparing preferred and non-preferred double-handed backhand techniques and complete inter-disciplinary investigations to understand what grip positions are most effective for individuals to learn double-handed backhands.

Analysis of Influence of the Load Plane Combined with Preload on Durability of Bearing

Angular ball bearings are commonly used whenever there is a demand to increase stiffness of a bearing. The aforementioned increase of stiffness can be achieved by obtaining proper preload in bearings. In common belief, preload has a negative consequence: it increases the load of rolling elements, which must lead to lower durability of bearing compared to the situation before the preload use.

Contact probabilities of an angular ball bearing under a combined axial and radial load

A contact probability model of an angular ball bearing is developed in this study by means of multi-body dynamics and a spherical grid division method. The model is used to analyze the contact probability of a ball surface of a typical angular ball bearing under different loading conditions. It is found that the contact probability of the ball with the inner and outer races of the bearing under a pure radial loading will have the largest probability distribution along the ball's circular profile intersecting the two contact points between the ball and the inner and outer races. Whilst the axial load on the ball bearing plays a decisive role in the stable distribution of the contact probability of the ball under various combinations of axial and radial loads. The study also shows that a steady-state wear will accumulate on the ball surface and the raceways when a large constant axial load is applied to the angular ball bearing.

The impact of vibration response due to rolling bearing components waviness on the performance of grinding machine spindle system

In this research, an analytical model based on a five-degrees-of-freedom nonlinear dynamical system was utilized to investigate the impact of vibration response due to inner race, outer race, and ball bearing waviness on the performance of grinding machine spindle system supported by two angular ball bearings. The waviness of rolling elements is modeled as a sinusoidal function is incorporated along the inner or outer races of bearing and ball surface. The elastic deflection and nonlinear contact force are calculated based on Hertzian contact model, while the shaft has five-degrees-of-freedom motions, three translational and two angular motions. The five–degrees-of-freedom nonlinear governing equations of the spindle system were developed taking into consideration the effect of outer race, inner race, and ball surface waviness, which are included in the kinematic constraints and force equilibrium equations of a ball. The developed model and its results are validated against results found in literature. Results by this paper indicate that the inner race waviness can significantly distort the tolerance and machining quality of grinding spindle-bearing systems more than does waviness in the outer race and ball elements. This is because the inner race waviness generates more complicated vibrations than the outer race and ball waviness. The most severe vibrations caused by the inner race waviness were found to occur when the waviness was of the order that is equal to multiple of number of balls in a bearing set plus or minus one ([Formula: see text]).

Development of two directional beam steering ECH/CD launcher for JT-60SA

Developments of a two directional beam steering electron cyclotron heating/current drive launcher for JT-60SA have been progressed based on a linear motion antenna concept. A full-scale (˜7 m) mock-up of the mirror steering structure with two kinds of bellows structures and an in-vessel support structure has been fabricated and tested in vacuum successfully. The support structure consists of a pair of angular ball bearings made of Si3N4 for rotational motion and a linear guide assembled by a rail and a housing made of non-magnetic stainless steel and Si3N4 balls. Solid lubricant has been used for the linear guide and it results in the improvement of the life time by a factor greater than 10 with respect to the case without lubricant. Considering that the mock-up test results satisfied the requirements for the bellows and support structures (reliable 40 cm linear movement, 105 cycles and angular rotation 30°, 104 cycles), the final design of the launcher is underway targeting the start of its fabrication.

Dynamic Parameter Analysis of Spindle Bearing Using 3-Dimension Quasi-Dynamic Model

Spindle bearing with high rotational speed is the kernel of many rotating machines which plays massive important role in the performance of the whole machine. There are also some deficiencies of the present quasi-dynamic mathematical models of the rolling bearing in analyzing the bearing dynamic parameters. This paper develops the 3D quasi-dynamic model with ball’s 6-DOF, cage’s 6-DOF, and driving ring’s 5-DOF under steady working stage, based on the analysis of the relative position of each component to determine the normal forces between each component and the analysis of the relative velocity of the contacting point to determine the tangential force between each component. This model can analyze the dynamic parameters, such as the spin-to-roll ratio of inner and outer rings, the angular velocity of rolling elements in y-axis of the location coordinate, the normal contact force of cage pocket and ball, the cage angular velocity and ball revolution velocity, and the gyroscopic moment under different working condition. Compared with the numerical calculation results of ADORE program, the results of the proposed model are able to accurately describe the change laws of the spindle bearing parameters.

The importance of bearing stiffness and load when estimating the size of a defect in a rolling element bearing

The change in the static stiffness of a bearing assembly is an important discriminator when determining the size of a defect in a rolling element bearing. In this article, the force–displacement relationships for defective bearings under various static radial loadings at various cage angular positions are analytically estimated and experimentally measured and analyzed. The study shows that the applied load has a significant effect on the static stiffness variations in defective rolling element bearings. The experimental measurements of the effect of the defect size on the varying stiffness of the bearing assembly, which has not been shown previously, provides valuable knowledge for developing methods to distinguish between defective bearings with defects that are smaller or larger than one angular ball spacing. The methods and results presented here contribute to the wider experimental investigation of the effects of loadings on the varying static stiffness of defective bearings and its effects on the measured vibration signatures. A large data set was obtained and has been made publicly available.

Thermo-mechanical behavior analysis of motorized spindle based on a coupled model

This article presents a thermo-mechanical coupled dynamic model for high-speed motorized spindles. The proposed model includes an angular ball bearing model, a thermal model, and a rotor dynamic model. The coupling relationship among these submodels is analyzed, and a solution procedure for the integrated model is designed. Based on the proposed model and solution procedure, the dynamic behaviors of the spindle system and the effects of the thermal displacement of the system on the behaviors are quantificationally discussed. Finally, an integrated dynamic test is carried out on a D62D24A-type motorized spindle, and the good agreement between the mathematical results and the experimental data indicates that the proposed model is capable of accurately predicting the dynamic properties of motorized spindles, and the accuracy of the model is improved when considering the thermo-mechanical coupled factor. The conclusions are useful for the dynamic design and the thermal compensation control of high-speed motorized spindles.

Multi-body Dynamics Analysis of the Axial-direction Vibration of Angular Contact Ball Bearing for Controlling the Infinite Vibration of Satellite Reaction Wheel

For satellite, it is necessary to reduce the vibration of rotating bearings in reaction wheel. In order to investigate the mechanism of the small vibration caused by bearings and its control scheme, we have conducted the multi-body dynamics analysis for angular ball bearing and reaction wheel. We focus on the effect of mechanical factors such as non-circularities of the inner and outer rings and the angle misalignment between them to the rotating secondary vibration component in the axial direction. It was found that the angle-misalignment enhances the rotating secondary vibration component when the inner ring involves second-order waviness. Also, axial-direction vibration is enhanced in the case that the waviness orders of inner and outer rings are coincident each other and angular-direction vibration is enhanced in the case that the difference in waviness orders of inner and outer rings is equal to 1 when the inner and outer rings involve the waviness. These vibrations are caused by the non-linear elastic contact between ball and raceway. Finally, from the parameter design, it was found that the effect of angular misalignment to axial vibration is greater than that of non-circularity of outer rings and these mechanical factors independently affect to the vibration.

The Influence of Preload on the Work of Angular Contact Ball Bearings

Abstract Optimum values of preload can be achieved in well-tried constructions and then applied in similar structures. For new structures, it is recommended to calculate the preload force and to test the correctness of calculation by means of experiments. In practice it may be necessary to introduce corrections, because not all real work parameters can be precisely known. Credibility of calculations depends, first of all, on the consistence between the assumptions concerning temperature conditions during work and elastic deformations of cooperating elements – first of all of a holder – and the real work conditions. The aim of the study is to determine how preload influences the work of a system of angular ball bearings, in relation to durability of bearing, moment of friction and rigidity of the bearing.

THE INFLUENCE OF LOCATION OF THE SURFACE OF LOAD ON THE VALUE OF PRELOAD IN THE SYSTEM OF ANGULAR CONTACT BALL BEARINGS

Angular contact ball bearings are commonly used when high stiffness of the bearing is needed. However, a significant stiffness increase can be achieved only through introducing preload (mounting tightness) to the system of angular ball bearings. The aim of the study is to determine how the location of a plane of a load influences the selection of preload in a system of angular contact ball bearings, and, in consequence, the durability of the bearing.

Design and application on experimental platform for high-speed bearing with grease lubrication

The experimental platform for high-speed grease is an important tool for research and development of high-speed motorized spindle with grease lubrication. In this article, the experimental platform for high-speed grease is designed and manufactured which consists of the drive system, the test portion, the loading system, the lubrication system, the control system, and so on. In the meantime, the high-speed angular contact ceramic ball bearings B7005C/HQ1P4 as the research object are tested and contrasted in the grease lubrication and oil mist lubrication. The experimental platform performance is validated by contrast experiment, and the high-speed lubricated bearing performance is also studied especially in the relationship among the rotating speed,load and temperature rise. The results show that the experimental platform works steadily, accurate, and reliable in the experimental testing. And the grease lubrication ceramic ball bearings B7005C/HQ1P4 can be used in high-speed motorized spindle in the circular water cooling conditions when the rotating speed is lower than 40,000 r/min or the DN value (the value of the bearing diameter times the rotating speed) is lower than the 1.44 × 106 mm r/min. Grease lubrication instead of oil mist lubrication under high-speed rotating will simplify the structure design of the high-speed motorized spindle and reduce the pollution to the environment.

Toward a 3D dynamic model of a faulty duplex ball bearing

Bearings are vital components for safe and proper operation of machinery. Increasing efficiency of bearing diagnostics usually requires training of health and usage monitoring systems via expensive and time-consuming ground calibration tests. The main goal of this research, therefore, is to improve bearing dynamics modeling tools in order to reduce the time and budget needed to implement the health and usage monitoring approach.The proposed three-dimensional ball bearing dynamic model is based on the classic dynamic and kinematic equations. Interactions between the bodies are simulated using non-linear springs combined with dampers described by Hertz-type contact relation. The force friction is simulated using the hyperbolic-tangent function. The model allows simulation of a wide range of mechanical faults. It is validated by comparison to known bearing behavior and to experimental results. The model results are verified by demonstrating numerical convergence.The model results for the two cases of single and duplex angular ball bearings with axial deformation in the outer ring are presented. The qualitative investigation provides insight into bearing dynamics, the sensitivity study generalizes the qualitative findings for similar cases, and the comparison to the test results validates model reliability.The article demonstrates the variety of the cases that the 3D bearing model can simulate and the findings to which it may lead. The research allowed the identification of new patterns generated by single and duplex bearings with axially deformed outer race. It also enlightened the difference between single and duplex bearing manifestation. In the current research the dynamic model enabled better understanding of the physical behavior of the faulted bearings. Therefore, it is expected that the modeling approach has the potential to simplify and improve the development process of diagnostic algorithms.

The influence of design and performance parameters of an angular ball bearing on the stiffness of gas turbine engine rotor supports

The paper deals with the influence of a radial bearing clearance, frequency rotation, as well as radial and axial forces on the displacement and stiffness of a ball bearing. The influence of the bearing stiffness on that of the support is assessed.

Characterization of Prototype 3MJ Flywheel Energy Storage System for Short-Cycle Electric Power Fluctuation Compensation

This paper describes design optimization and experiment of low-cost flywheel energy storage system (FESS) using the conventional ball bearings under low vacuum condition to compensate short-cycle electric power fluctuation caused by solar and wind power generation systems. To investigate the feasibility of the FESS for electric power compensation, specification of the FESS with 3MJ storage capacity was optimized to minimize mechanical loss including bearing loss, seal loss, and windage loss. Based on the optimization result, a prototype FESS was built and tested. As a result, the prototype FESS, which consists of flywheel rotor with 1m diameter and 0.65m thickness, angular ball bearings, ferrofluidic seal, and general purpose induction motor, achieves charging/discharging efficiency of 75.4%/77.2% in approximately ten minutes charging and discharging cycle. In addition, the prototype FESS reduces by up to 89.9% fluctuation component in the frequency range > 0.0025 Hz of the simulated solar electric power fluctuation pattern. Furthermore, loss characteristic of the prototype FESS was revealed and discussed in detail.

Cage Instabilities in High-Speed Ball Bearings

The dynamic model of the cage in high-speed ball bearing was developed according to the geometry and force relationship between bearing elements. Based on this dynamic model, cage instability was researched through mass center whirl. The effect of clearance ratio, load and bearing rotation speed on cage instability were studied by taking type 7004 angular ball bearing as an example. The results shown that the increase of clearance ratio and radial load makes cage stability lowered, and the cage stability could be enhanced by increasing the axial load and bearing rotation speed.