Number Of Rollers Research Articles

The performance evaluation of hybrid roller bearings under lubricant contamination conditions

Purpose This paper aims to evaluate the dynamic performance of hybrid roller bearings under lubricant contamination. Design/methodology/approach Some steel rollers in traditional cylindrical thrust roller bearings were replaced with ceramic rollers to assemble hybrid roller bearings. Friction experiments were conducted under lubricant contamination using alumina as the contaminant, and simultaneous vibration acceleration signals from the bearings were collected to evaluate their tribological and dynamic performance. Findings Under lubricant contamination, hybrid roller bearings with a sufficient number of ceramic rollers exhibit greater wear resistance compared to traditional all-steel bearings. There is a noticeable suppression of energy in both tangential and normal frequency bands of the bearings, with more pronounced suppression observed in higher frequency bands. Originality/value This study provides valuable insights for the development of hybrid ceramic bearings. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2024-0291/

Evaluation and analysis of abrasive wear resistance of hybrid roller bearings under lubricant contamination

Abrasive wear is a common failure mode of rolling bearings. To enhance the resistance of traditional all-steel bearings to abrasive wear, the structure of traditional all-steel cylindrical thrust roller bearings has been appropriately adjusted, and hybrid roller bearings have been formed by replacing some of the steel rollers in the traditional bearings with ceramic rollers. The frictional performance of hybrid roller bearings under lubricant contamination conditions was analyzed, and the wear reduction mechanism was discussed. The results show that under the condition of lubricant contamination, replacing the appropriate amount of ceramic rollers not only helps reduce friction and decrease wear but also contributes to improving the overall temperature rise of the bearing. Furthermore, when the total amount of contaminants is constant, a specific threshold exists for the impact of replacing the number of rolling elements on reducing mass loss. For a substantial reduction in wear with hybrid roller bearings, the replacement rollers should constitute at least one-fifth of the total number of rollers. The wear reduction observed in hybrid roller bearings results from a combination of crushing and refinement, grinding and finishing, and self-healing mechanisms.

Thermal infrared imaging for conveyor roller fault detection in coal mines.

As a key mechanism of belt conveyor, the health status and working state of its parts have a profound impact on whether the belt conveyor can run normally and safely. In the composition of the standard belt conveyor, the number of rollers is numerous and scattered. At the same time, under the complex environment of the work site, the fault detection of each roller is particularly difficult. In order to solve the above problems, a diagnosis method based on thermal infrared image features is proposed to detect the faults of each roller mechanism in the belt conveyor. Firstly, the position of the idler is identified based on the YOLOv4 identification method, and then the sticking resistance and bearing damage of the idler are detected based on the temperature difference discrimination method. In this paper, the target recognition method based on YOLOv4 is used to identify the position of the roller, and the recognition accuracy is 93.8%, which meets the requirements of the project. The infrared image obtained by the dual-spectrum camera is used to distinguish the fault of the idler in the coal mine. The temperature of the bearing and surface of the normal roller increases rapidly within 10 minutes of operation, and the temperature changes slightly after 10 minutes of operation. The bearing damaged idler has a greater friction effect at the bearing, so the temperature at the bearing rises faster, and there is a temperature difference of about 7°C between the bearing and the normal roller. The surface temperature of the idler in the blocking state is also fast for about 20 minutes, and there will be a temperature difference of about 8°between the surface of the idler and the normal roller. In this paper, it is determined that the temperature rise coefficients of the roller surface and bearing under normal conditions are 24% 28% and 18% 22% respectively. It is determined that the threshold value of the temperature rise coefficient in the blocking state and the damaged state is 30% and 25% respectively, that is, when the surface temperature rise coefficient of the roller is detected to be more than 30%, it is determined that the card resistance fault occurs, when the temperature rise coefficient at the roller bearing is detected > 25%, the bearing damage fault is judged.

Design optimisation of roadside safety roller barriers

Safety roller barrier (SRB) is an innovative road safety device that utilises foam rollers to absorb and convert shock energy into rotational energy, showcasing its remarkable ability to minimise the risk and severity of casualties in road accidents. In this study, a simulation-based optimisation approach was employed to obtain the optimal design for the SRB. Quasi-static and dynamic mechanical properties of the construction materials were experimentally obtained. SRB finite element (FE) models were then created based on installed systems in multiple Australian cities. The model was validated using full-scale TL4 crash tests according to the specifications outlined in the Manual for Assessment of Safety Hardware (MASH). Subsequently, a parametric study was conducted to explore the influence of design parameters such as post spacing, rail height, and roller number. Finally, a parallel Bayesian optimisation algorithm was applied to re-design the SRB system with enhanced performance and reduced cost. This optimisation process yielded several sets of optimal parameters, paving the way for a more effective and economically viable SRB design.

Contact force and pressure analysis of the three-row roller pitch bearing in a large-scale wind turbine

Pitch bearings are the key components of wind turbines (WTs). The reliability of pitch bearings affects the electric energy output efficiency of WTs. Due to its large loading ability, constant contact angle and high stiffness, the three-row roller slewing bearing (TRSB) is becoming a more attractive choice as a pitch bearing, especially in large-scale WTs. The contact force and pressure distributions significantly affect the fatigue life of a three-row roller pitch bearing (TRPB). Therefore, it is essential to propose a precise calculation method for the contact force and pressure. The present work establishes a quasi-static five degree-of-freedom (DOF) mathematical model for TRPBs, in which the bearing under general loading conditions is considered. The influences of combined external forces, overturning moments and inner ring misalignment angle on the contact force and pressure distributions of TRPBs are comprehensively investigated. According to the analysis results, the overturning moment and axial force can significantly affect the number of load-carrying rollers in each row. Furthermore, a slight variation of the inner ring angular misalignment has a significant effect on the contact force and pressure of TRPBs. Finally, it is more prone to pressure concentration in the non-crowned roller than that in the crowned roller, especially in the case of the inner ring with a misalignment angle. Since the high calculation efficiency and accuracy, the proposed method has remarkable potential applications in the fatigue life prediction and design of TRPBs.

Analysis and evaluation of the synergistic effect of ceramic materials and surface texture on anti-abrasive particle wear under rolling conditions

Damage to mechanical components caused by contaminant ingress is a common failure. In response to this issue, this study introduces a synergistic abrasion reduction method based on the combined application of ceramic materials and surface texturing. Using cylindrical thrust roller bearings as an illustration, circular textures were applied to the raceways, and a small number of steel rollers were substituted with ceramic ones. Moreover, alumina was introduced into the lubricant as a contaminant. The frictional and dynamic performance of the "ceramic-textured surface" combination under lubricant contamination conditions was explored and compared with corresponding single abrasion reduction techniques. The synergistic abrasion reduction mechanism of the "ceramic-textured surface" combination was also examined. The findings reveal that under lubricant contamination conditions, the synergistic abrasion reduction method surpasses individual abrasion reduction methods and demonstrates a certain degree of complementarity. Compared with traditional all-steel bearings, textured bearings with four ceramic rollers have reduced the average frictional force by approximately 56.82 %, and the mass loss of the shaft washer and seat washer has been reduced by approximately 81.01 % and 80.86 %, respectively. Rolling elements treated with the synergistic abrasion reduction method exhibit enhanced resistance to abrasive particle wear. This improvement is attributed to the collaborative effects of various mechanisms, including crushing and refinement, capture and storage, grinding and finishing, as well as self-healing and smoothing.

Determination of Mechanical Power Loss of the Output Mechanisms with Serially Arranged Rollers in Cycloidal Gears While Taking into Account Manufacturing Tolerances

Despite their complex design, cycloidal gearboxes are characterized by high efficiency. Nevertheless, due to friction, some power is lost during gearbox operation. Basically, these losses occur in two structural nodes: the cycloid gearing and the output mechanism. Since the first of these nodes has been well discussed in the literature, the output mechanism will be discussed in this article. The design of the output mechanism has a significant impact on mechanical power losses. There are several mechanism design solutions. One of them is a mechanism with serially arranged rollers. Three solutions that are different in design but work identically will be discussed. Due to this affinity, a single, common mathematical model will be used to determine the value of losses. As will be shown, the value of losses is directly affected by the backlash, number, and diameter of the rollers used in the output mechanism and indirectly by the ratio and eccentricity of the cycloidal gearbox. Sample calculations were carried out using the developed model of mechanical power losses in the output mechanism. This made it possible to analyze the distribution of backlash created by manufacturing tolerances. It was also shown that the backlash has a significant effect on the number of rollers involved in torque transmission, as well as on the distribution of loads, contact pressures, and mechanical power losses.

Ways to reduce the risk of emergencies on belt conveyors operating in mining enterprises

Since the majority of emergencies on belt conveyors of mining enterprises are associated with the conveyor framework, the article considers the failures of its elements - roller supports. The process of functioning of the framework is presented as a Markovian process of death and reproduction for a system of n parallel connected elements (roller supports) with intensity of failure and recovery λ r and μ r, respectively. The maximum permissible number of non-working roller supports, as well as the required number of roller supports replacement per shift to prevent an emergency on the conveyor, are determined. The value of the risk of conveyor framework failure K was also determined. Thus, for the given operating conditions, load flow characteristics and conveyor parameters, it is possible to calculate the maintenance intensity at which the risk of an emergency is minimal. This allows for efficient planning of belt inspections and repairs. To eliminate the risk of emergencies a patent-pending method for monitoring the technical condition of a belt conveyor framework by automatically monitoring the number of idle rollers on the framework has been developed. This prevents accidents caused by belt breakage and fire, as well as loss of traction of the conveyor drive.

A New Denoising Method for Belt Conveyor Roller Fault Signals.

In the process of the intelligent inspection of belt conveyor systems, due to problems such as its long duration, the large number of rollers, and the complex working environment, fault diagnosis by acoustic signals is easily affected by signal coupling interference, which poses a great challenge to selecting denoising methods of signal preprocessing. This paper proposes a novel wavelet threshold denoising algorithm by integrating a new biparameter and trisegment threshold function. Firstly, we elaborate on the mutual influence and optimization process of two adjustment parameters and three wavelet coefficient processing intervals in the BT-WTD (the biparameter and trisegment of wavelet threshold denoising, BT-WTD) denoising model. Subsequently, the advantages of the proposed threshold function are theoretically demonstrated. Finally, the BT-WTD algorithm is applied to denoise the simulation signals and the vibration and acoustic signals collected from the belt conveyor experimental platform. The experimental results indicate that this method's denoising effectiveness surpasses that of traditional threshold function denoising algorithms, effectively addressing the denoising preprocessing of idler roller fault signals under strong noise backgrounds while preserving useful signal features and avoiding signal distortion problems. This research lays the theoretical foundation for the non-contact intelligent fault diagnosis of future inspection robots based on acoustic signals.

Universal accuracy model for three different types of precision bearings with three basic structures under quasi-static conditions

A universal accuracy model is established under quasi-static conditions to predict motion accuracies and directly compare error averaging abilities among three different types of precision bearings (including fluid hydrostatic, porous air, and cylindrical roller bearings) with three basic structures (including linear (i.e., guideway), journal, and thrust bearing structures) used widely in precision and ultra-precision machine tools. To introduce the universal accuracy model, three types of precision guideways are taken as examples. Uniform generalized coordinate systems are used to evaluate error motions and uniform averaging coefficients are defined to assess error averaging abilities. It is found that the total error averaging abilities consist of basic and layout error averaging abilities characterized by corresponding averaging coefficients. The total averaging coefficients are the products of basic and layout averaging coefficients which are independent of each other. The porous air bearings have strongest basic error averaging abilities, followed by the fluid hydrostatic bearings, and finally followed by the cylindrical roller bearings. The layout averaging coefficients are related to the number and layout of pads or rollers which are working like some structural filters for a certain kind of error motion. A summary of accuracy experiments based on previous studies provides evidence of the existence of layout error averaging abilities. The content discussed in this paper is of significant importance for the selection and design of precision bearings.

Geometry and Kinematics of the Mecanum Wheel on a Plane and a Sphere

This article is devoted to a study of the geometry and kinematics of the Mecanum wheels, also known as Ilon wheels or the Swedish wheels. The Mecanum wheels are one of the types of omnidirectional wheels. This property is provided by peripheral rollers whose axes are deviated from the wheel one by 45 degrees. A unified approach to studying the geometry and kinematics of the Mecanum wheels on a plane and on the internal or external surface of a sphere is proposed. Kinematic relations for velocities at the contact point of the wheel and the supporting surface, and angular velocities of the roller relative to the supporting surface are derived. They are necessary to describe the dynamics of the Mecanum systems taking into account forces and moments of contact friction in the presence of slipping. From the continuous contact condition, relations determining the geometry of the wheel rollers on a plane and on the internal or external surface of a sphere are obtained. The geometric relations for the Mecanum wheel rollers could help to adjust the existing shape of the Mecanum wheel rollers of spherical robots and ballbots to improve the conditions of contact between the rollers and the spherical surface. An analytical study of the roller geometry was carried out, and equations of their generatrices were derived. Under the no-slipping condition, expressions for rotational velocities of the wheel and the contacting roller are obtained. They are necessary for analyzing the motion of systems within the framework of nonholonomic models, solving problems of controlling Mecanum systems and improving its accuracy. Using the example of a spherical robot with an internal three-wheeled Mecanum platform, the influence of the rollers on the robot movement was studied at the kinematic level. It has been established that the accuracy of the robot movement is influenced not only by the geometric parameters of the wheels and the number of rollers, but also by the relationship between the components of the platform center velocity and its angular velocity. Results of the numerical simulation of the motion of the spherical robot show a decrease in control accuracy in

Detection of movement resistance and friction coefficient in the transport of building materials and construction materials

In the production of building materials and construction materials, continuously operating conveying equipment is commonly used, including roller conveyors. Roller conveyors are devices designed for horizontal, slightly ascending or descending transport of piece products moving on a system of rotating rollers of different shapes (cylindrical, conical, disc, pulley or according to the profile of the conveyed object). The rotating rollers are placed in the track frame (supporting structure), which can be either stable, relocatable or adjustable (height and length adjustable, so-called scissor conveyors). An analogue of the roller conveyor is the pulley conveyor, where instead of rollers, discs - pulleys are mounted on a non-rotating axis. Several discs are installed on the axis with gaps. The pulleys on adjacent axes overlap so that there is no continuous gap. The track is used for handling flat building parts and objects such as metal sheets, glass panes, furniture parts, etc. When transporting item building materials or bulk building materials placed in storage boxes which are transported on a powered roller track on pallets, a driving force is required depending on the angle of inclination of the roller track, the weight of the load, the number of rollers on which the load rests and the coefficient of shear friction during movement. The paper presents a laboratory device that has been designed to detect the adhesion force during the transport of piece loads by a roller conveyor. On the implemented device, it is possible to determine in laboratory conditions the amount of resistance to the movement of the load on the driven roller conveyor depending on the weight of the load. The paper presents measured values of the shear friction coefficient during the movement of a steel storage box on a driven roller track. In this paper, a driven roller track is used for laboratory tests, where the drive of the rollers is implemented by so-called short chains. In addition to horizontal tracks, this chain drive allows you to drive rising tracks with variable gradients or even rising curved tracks.

Влияние микрогеометрических параметров сферической поверхности ролика на звуковое давление и вибрацию подшипника

In a production environment of JSC UPC Volzhsky it is shown how to increase the vibration discharge of bearings with conical rollers due to the use of rollers with the specified microgeometric parameters of the spherical surface made in the general production flow. The sphere is formed under the combination of rough grinding, finish grinding and final grinding using an assembled abrasive tool consisting of three rolls of various characteristics. It was found that in a bearing, with sequential replacement of rollers, where sphere roughness varies in the range of 0.10 Ra ≤ 0,.20 microns for rollers with roughness Ra ≤ 0,10 microns, the average value of the microgeometric parameters of the roller sphere in bearings (Ra, undulation W, deviation of circularity Δ) decreases by 2,4 – 4,3 times. The impact assessment of bearing rollers set having different parameters of the microgeometry of the spherical roller end on the sound pressure and vibration of the bearing was carried out. It was found that with an increase in the number of rollers with microgeometric parameters of the sphere closer to the lower edge of the tolerance field, the values of the overall vibration level, the vibration level in the third frequency band and the sound pressure level of the bearing improved. A statistical analysis of these parameters was carried out. The significance of the analyzed factors and conditions for increasing the vibration discharge of the bearing while ensuring processing modes within the framework of the current technological process are determined. Correlation and functional relationships between the average values of the microgeometric parameters of rollers spheres in bearings and the parameters of sound pressure and vibration were found.

Study on contact and vibration characteristics of composite cylindrical roller bearings

PurposeThe purpose of this paper is to establish a dynamic analysis model of composite cylindrical roller bearings, investigate the effects of different working conditions on the kinematic characteristics of composite bearings and compare the differences between them and solid roller bearings.Design/methodology/approachThis paper establishes a dynamic analysis model for composite cylindrical roller bearings and proves the correctness of the established model by establishing dynamic vibration experiments and contact theory for composite roller bearings. Comparative analysis was conducted on the effects of coupling changes in rotational speed, load, number of rollers and filling ratio on parameters such as bearing static stiffness, contact stress and vibration acceleration.FindingsThe composite roller can enhance the bearing’s operational stability and minimize contact stress, but that a higher filling ratio is going to increase the bearing’s stiffness. The acceleration degree of bearing vibration, the load on the outer raceway nodes and the bearing stability all decrease as inner ring speed rises.Originality/valueA dynamic calculation model of composite cylindrical roller bearings is established, and the influence of multiparameter coupling changes on bearing vibration and contact is studied, which lays a foundation for the structural improvement of the bearings.

Nonlinear vibration characteristics of rolling bearing considering flexible cage fracture

Rolling bearing is one of the critical parts of the transmission system and has a high demand for operating conditions. Suitable operating conditions can ensure that the rolling bearing has a higher rotation accuracy, which significantly impacts the performance of the transmission system. However, under some unsuitable operating conditions, the rolling bearing in the transmission system is faced with failure and other problems. Cage failure is one of the most common bearing failures. In particular, the cage fracture analysis is the most difficult among rolling bearing failures. In order to research its nonlinear vibration characteristics under cage fracture, a nonlinear model of the rolling bearing (4Nb+4 degrees of freedom) considering cage fracture is established. The contact between bearing rings and the rollers, the circumferential interaction between the flexible cage and the rollers, and the interaction between the rollers under the cage fracture fault are considered. Subsequently, the nonlinear characteristics under cage fracture are analyzed. The nonlinear collision forces of roller and cage under cage fracture and different cage clearances are compared. The results show that the collision force between rollers and the cage is greater when fractured than when the cage is healthy. Under multiple cage fractures (the roller number is odd), more prominent frequency doubling phenomena may occur as the number of fractures increases. More shocks are reflected in the relative angular displacement and waveform. Under multiple cage fractures (the roller number is even), the number and interval of fractures can be determined through the waveform and envelope spectrum. The research in this paper can help the health monitoring and fault diagnosis of bearing cages.

Methods for multi-segment continuous cable analysis

Cables are invaluable members for some applications of engineering. The specialty is due to its behavior under transverse loads. Having almost no rigidity in transverse direction makes cables different from other structural elements. In most applications, cables are assumed to be two force members. However, not only its weight but also its application with roller supports makes them different structural elements. Generally, cables are assembled as single-segmented cables (SSC) where they are fixed at their ends. However, in most of the SSC applications, cables have intermediate supports which can be rollers or sliders. These type of cable applications are called as multi-segment continuous cables (MSCC). In MSCC systems, the cable fixed at its ends and supported by a number of intermediate rollers. Total length of cable is constant, and the intermediate supports are assumed to be frictionless and stationary. In this problem, the critical issue is to find the distribution of the cable length among the segments in the final equilibrium state, so reactions at all supports can be found. Two methods are proposed for the segment length adjustment based on the stress continuity among the cable. These methods are named as direct stiffness method and tension distribution method (relaxation method). Results calculated from the proposed methods are verified by both the reference benchmark problems and commercial finite element program.

Experimental Study on the Effect of Off-Sized Rollers on the Dynamic Load Distribution in a Cylindrical Roller Bearing

Abstract The differences in the roller diameters within a roller bearing are unavoidable in practice, which is known as the off-sized effect. The off-sized effect results in the dynamic variation of the load distribution in bearings and further the abnormal vibration and premature failure of bearings. This paper experimentally investigates the effect of off-sized rollers on the dynamic load distribution in a cylindrical roller bearing. Different configurations of off-sized rollers are given considering the oversized and undersized roller conditions, and the number and position of off-sized rollers. The real-time roller-raceway contact loads distributed in the bearing are measured under these test cases. The results show that a single off-sized roller leads to the loading change directly on itself and further the load rebalances among the adjacent rollers. Under the conditions of multiple off-sized rollers, a stack effect of the competition rule of roller loading dominates the variation range of the dynamic load distribution. As results of the stack effect, among all roller configurations, the configuration of multiple off-sized rollers adjacent to each other leads to the minimum range of the dynamic load distribution, while the configuration of two off-sized rollers separated by a regular roller leads to the maximum one.

Hemolysis performance analysis and a novel estimation model of roller pump system

ObjectiveHemolysis performance is a crucial criterion for roller pumps utilized in life supporting system. In this study, the factor of hemolysis for roller pumps was selected as the target, and an estimation formulation was built to evaluate its hemolysis. MethodsSeveral models were proposed and then simulated with the assistant of Computational fluid dynamics (CFD) framework. The hemolysis performance was calculated using the power law model based on CFD and the estimation model in accordance with geometry parameters proposed in this study. The results of the in vitro experiments were compared with the simulation results. Power law model with the lowest error was utilized in following analysis. ResultsAs indicated by the simulation result, the rotary speed most significantly affected the hemolysis performance of roller blood pumps, followed by roller number and diameter of tube. The index of hemolysis (IH) for roller blood pumps at a rotary speed of 20–100 rpm ranged from 8.73E-7 to 8.07E-5. The relative error of the estimation model (4.93%) was lower than of the power law model (6.78%). ConclusionThe IH led by pumps shows a significant, nonlinear relationship with the rotary speed. The design of multiple rollers design is harmful for hemolysis performance and larger diameter of tube exhibits decreased hemolysis at constant flow rate. An estimation formula was proposed with lower relative error for roller pump with the same shell set, which exhibited reduced computation and elevated convenience. And it can be utilized in hemolysis estimation of roller pumps potentially.

Forest conversion into pasture selects dung beetle traits at different biological scales depending on species pool composition.

The conversion of forests into open areas has large effects on the diversity and structure of native communities. The intensity of these effects may vary between regions, depending on the existence of native species adapted to open habitats in the regional pool or the time since habitat change.We assess the differences in species richness and functional diversity of dung beetle communities (Coleoptera: Scarabaeinae) between native forests and novel pasturelands of the Atlantic Forest and the Cerrado, two biomes with contrasting histories of human occupation in Brazil. We conducted standardized surveys in seven forest fragments and adjacent pastures in each region and measured 14 traits in individuals collected in each type of habitat at each particular site. We calculated functional richness, functional evenness, functional divergence, and community-weighted mean of traits for each area, and analyzed individual variation through nested variance decomposition and Trait Statistics.Communities were richer and more numerous at the Cerrado. We did not find any consistent relationship between functional diversity and forest conversion beyond the changes in species diversity. Although landscape changes were more recent at the Cerrado, the colonization of the new habitat by native species already adapted to open habitats lessens the functional loss in this biome. This indicates that habitat change's effects on trait diversity depend on the regional species pool rather than on time since land conversion.Forest conversion effects were primarily due to internal filtering. The effects of external filtering only appear at the intraspecific variance level, with contrasting differences between the Cerrado, where traits related to relocation behavior and size are selected, and the Atlantic Forest, where selection operates for traits related to relocation behavior and flight. These results evidence the importance of considering individual variance to address the responses of dung beetle communities to forest conversion.

Accuracy prediction and roller number optimization of journal roller bearing based on averaging coefficient considering raceway roundness error

Accuracy prediction and roller number optimization of journal roller bearing based on averaging coefficient considering raceway roundness error