Cylindrical Roller Research Articles

Method for the consideration of statistically distributed geometrical deviations in the design of cylindrical roller bearing arrangements

Rolling bearings are of great importance in all areas of mechanical engineering due to their precise and low-friction guidance of rotating components at low cost. The design of rolling bearing arrangements is usually based on approximately ideal geometries of bearings and adjacent parts on which the bearing seats are located. However, real components inevitably show statistically distributed deviations from their nominal shapes, which are limited by tolerances. Tight tolerances result in high manufacturing costs while on the other hand their expansion leads to an increase of occurring geometrical deviations which cause changes in the bearing-internal contact and load conditions and can thus impair the operating behavior of the bearing, e.g. with regard to fatigue life, frictional torque or vibration behavior. By taking these effects into account in the design stage, potential problems in operation can be identified early during development and countermeasures can be taken, e.g. by adjusting bearing and seat tolerances. This enables an improvement of overall product quality and a reduction of costs. This paper presents a method for the integration of component deviations in the computation of the fatigue life (Lnmr) and dynamic behavior of cylindrical roller bearing arrangements—both of which are crucial design criteria—based on a combination of statistical tolerance analysis and multi-body simulations. The method is applied to an exemplary use case for illustration.

Modeling of double-row cylindrical roller bearing under combined loads and angular misalignment

Abstract To enhance the reliability of the double-row cylindrical roller bearing (DCRB), a new quasi-static model, which is capable of considering inner ring misalignment and combined loads, has been established. This model was used to calculate the distribution of internal loads and contact pressure. First, the model was verified with published data. Secondly, systematic parameter analyses are conducted to investigate how axial load, inner ring misalignment and roller profile influence the contact performance. The results indicate that when the bearing is subjected to a combined load, the difference between the radial loads borne by the two rows increases with the increase of axial load. The combined load and misalignment of the inner ring would cause significant changes in the numerical value and distribution of contact load and pressure between the rollers and raceways. The roller profile optimization can reduce contact pressure and alleviate the edge effect.

Tribological Behavior of Hydrocarbons in Rolling Contact

In the analysis of tribological contacts, the focus is often on a singular question or result. However, this entails the potential risk that the overall picture and the relationships could be oversimplified or even that wrong conclusions could be drawn. In this article, a comprehensive consideration of test results including component and lubricant analyses is demonstrated by using the example of rolling contact. For this purpose, thrust cylindrical roller bearings of type 81212 with unadditized base oils were tested in the mixed-friction area. Our study shows that by using an adapted and innovative surface analysis, a deeper dive into the tribo-film is feasible even without highly sophisticated analytical equipment. The characterization of the layers was performed by the three less time-consuming spatially resolved analysis methods of µXRF, ATR FTIR microscopy and Raman spectroscopy adapted by Schaeffler. This represents a bridge between industry and research. The investigations show that especially undocumented and uncontrolled contamination of the test equipment could lead to surprising findings, which would result in the wrong conclusions. Simple substances, like hydrocarbons, are demanding test specimens.

Nondestructive testing method of Si3N4 ceramic bearing cylindrical roller surface defects based on depthwise separable convolution coupled with identity block ASPP

Nondestructive testing method of Si3N4 ceramic bearing cylindrical roller surface defects based on depthwise separable convolution coupled with identity block ASPP

Влияние износа инструмента в процессе физического моделирования шевингования-прикатывания цилиндрических зубчатых колес на параметр шероховатости

The main issues related to the results of an experimental study aimed at modeling of the combined (cutting-deforming) finishing process of a gear processing, i.e. cylindrical gear shaving and rolling, under turning with a special combined cutting-deforming tool, which is a single-tip tool of a cylindrical work, divided into equal working areas. Due to the proprietary exploratory procedure used for prototype process, in one operation of a compact cylindrical work, a gear processing of a sufficiently large batch of horisontal wheels-representatives with average parameters, consisting of several thousand pieces, is simulated on a CNC lathe. The analysis of the results of the experiment was treated, allowing us to obtain information about gear processing of a large batch of gears in laboratory conditions. The roughness parameter of the work on workpiece areas is determined, the boundaries of tool degradation for this parameter are revealed. The revealed pattern of tool degradation appears to be the following: the prevailing wear of the tool occurs along the back surface due to its design feature, i.e. zero angle of its back, aggravated by the technological characteristics of the process (shaving - rolling), in which the back is involved in the surface plastic deformation, in particular, crushing a metal layer under the influence of a significant normal load. This results in frictional load taking place between its back surface and the surface of the proccesed workpiece. Tool degradation along the front surface, accompanied by its tool cutter blunting of its cutting edge, contributes to further deterioration of cutting process conditions (when stock removal of about 0.02 mm), and at the same time increases the proportion of surface plastic deformation (when shaving– rolling). This, as a result, increases the workpiece material share, which should be removed not by cutting, but by surface plastic deformation, thereby further redoubling a wear bit in its back surface.

Influence of a Pair of Unequal Rotational Fluxes on Entrained Gaseous Filament

Abstract Efforts are made to elucidate a comprehensive analysis of entrainment dynamics triggered by a couple of unequal rotational fluxes within a viscous pool. Cylindrical rollers are employed to establish the rotational field. The top drum is equally submerged in both phases and also it provides a constant rotational inertia. Concomitantly, the bottom roller is completely submerged in the viscous bath, and it provides an unequal rotational strength in reference to top roller. The average rotational strength of both rollers is measured using average Capillary number (Caavg). The entrainment phenomenon is strongly influenced by both Caavg and gap between the rollers (W/D). Characterization of entrained filament is elucidated by predicting the horizontal distance (L*), radial distance (r*), temporal vertical displacement (Y*), maximum vertical displacement (Ymax*), width (H*), and location of V-shaped diversion (Øs*). Characterization of liquid tip is performed by measuring the travel rate (γ*) along periphery of drum from receding to advancing junction. Air mass ejection from filament tip is analyzed by estimating the first bubble ejection time (t1st*), volume of accumulated of ejected gaseous masses (v*), and ejection frequency (f). Furthermore, the effect of gravitational pull (specified by Archimedes number, Ar) and viscous drag (measured by Morton number, Mo) on the pattern of entrained air filament is described. Lastly, an analytical framework is established to determine the width of the V-junction by balancing the important influencing forces, which are strongly affecting the filament. Analytical observations show a satisfactory agreement with numerical findings.

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.

An IGSA-VMD method for fault frequency identification of cylindrical roller bearing

The number of intrinsic mode function (IMF) and quadratic penalty factor (QPF) are two important parameters in variational mode decomposition (VMD) for fault frequency identification of cylindrical roller bearing, but it is difficult to obtain the optimal values by experiential knowledge. Accordingly, an improved gravitational search algorithm (IGSA) with nonlinear decreasing inertia weight factor is integrated into the VMD, namely as IGSA-VMD, for adaptive selection of the two parameters. Firstly, a target function of minimum envelope entropy is defined in the IGSA to optimize the IMF number and QPF. Secondly, the optimized two parameters are employed to decompose the measured vibration signals into several IMF components by utilizing the VMD. Finally, the feasibility of proposed IGSA-VMD method is validated through the fault frequency identification of cylindrical roller bearing and the benchmark test dataset from Case Western University. Both the simulative and experimental results show that the extracted fault frequencies are highlighted more clearly by utilizing the IGSA-VMD comparing to the PSO-VMD and the traditional VMD. The proposed IGSA-VMD is a more efficient and effective vibration diagnostic approach for outer race and roller fault frequencies extraction from original vibration signals of cylindrical roller bearings in rotary machines.

The acoustic-vibration characteristics of cylindrical roller bearings with raceway failures: Simulation and experiment

This paper presents a mathematical model for cylindrical roller bearings, the precision noise test and simulation investigation are employed, the discussion focuses on the systematic investigation of the vibration characteristics, noise properties, and noise transmission attributes of defective bearings. The findings indicate that severe displacement oscillations of rollers and oil film oscillations can be observed due to the raceway fault, the average slip rate of rollers is seriously affected, resulting in a reduction in the operational stability of the cage. The noise shock is also introduced, which is primarily reflected in the mid-frequency range (670–8000 Hz) of the spectrum, leading to a deviation from the normal distribution of noise data points. This characteristic makes it challenging to detect noticeable shock signals when testing bearing noise at a distance. This research holds the promise of deepening comprehension of faulty bearing dynamics, thereby furnishing richer means for precise fault diagnosis.

Slipping in cylindrical roller bearings at the simultaneous rotation of inner and outer rings

Slipping in cylindrical roller bearings is investigated at the simultaneous rotation of inner and outer rings. A 6-DOF dynamic model is developed to analyze roller, cage, and ring dynamics, assessing driven and resistance moments, cage rotating speed, and roller-raceway sliding velocities. The results show that if the inner and outer rings rotate inversely, the motion of rollers is relatively stable, which is beneficial for preventing the slipping in the bearing. However, if the inner and outer rings rotate in the same direction, the churning moment of rollers is high. Meanwhile, more rollers have a negative value of the sum of the churning moment and traction moment. This leads to an increase in the slipping of the bearing.

Confirming dark groove microstructural alterations as WEC initiation first stage in cylindrical roller thrust bearings lubricated with WEC critical oil

In a recent work, after conducting disc-on-disc tests under the influence of hydrogen, the authors identified microstructure alterations, the so-called dark grooves, as possible initial stages of WEC formation. In this work, the aim is to investigate whether dark grooves also constitute the initial stages of WEC in cylindrical roller thrust bearings (CRTBs) tested under the influence of WEC-critical oils. BEM simulations of the roller/washer contact were conducted to identify the coordinates of the maximum subsurface shear stresses, the region in which the first stages of failure are likely to start. Subsequently, CRTB tests were carried out, where prematurely stopped bearings were characterized considering the BEM results. The initial signs of failure i.e., the dark grooves consisting of nanopores and nanograins, were found in the maximum subsurface shear stress regions indicated by the BEM simulations.

<b>Application of Cylindrical Roller Bearings with Ribs to Gear Units of Railway Vehicles</b>

<b>Application of Cylindrical Roller Bearings with Ribs to Gear Units of Railway Vehicles</b>

An Experimental Study on the Distribution of Grease in Cylindrical Roller Bearings

The lubrication performance of bearings is greatly influenced by the distribution of the lubricant. In this study, a cylindrical rolling bearing test rig was constructed and presented. The distribution of grease and lubricating oil along the contact region was examined using the laser-induced fluorescence technique, and the thickness of the layer was determined. The lubricating oil and grease layer thickness distribution map was acquired. The effects of supply amount, thickener content, and speed on grease distribution were examined. Mechanisms for replenishing the line contact area were investigated.

Transient characteristics of misaligned roller bearing considering thermal-fluid-solid coupled

Misalignment of roller bearings is a characteristic defect mode, which is accompanied by variations in thermal, mechanical, and lubrication performances. Regarding this aspect, a novel model considering the thermal-fluid-solid coupled effect is proposed to evaluate the performance evolution of lubricated cylindrical roller bearings (CRB) under misalignment states. The proposed model regards structural parameters, contact characteristics, and lubrication status as time-varying variables. By integrating the quasi-static model of CRB with a thermal network model, the influence of internal contact shape and stress on the thermal characteristics of misaligned bearings is reasonably considered. The accuracy of the proposed model is validated through the thermal performance experimental platform. In addition, the influence of thermal and misalignment on time-varying mechanical properties such as contact load, radial stiffness, and clearance loss is assessed. Eventually, the deterioration of the lubrication performance over operational time is quantitatively characterized by the time-varying film thickness at the load region.

Effect of different chemical conversion coatings on the tribological performance of cylindrical thrust roller bearings under conditions of dry friction and solid lubrication

The chemical conversion coating technology, as a surface technique, can effectively reduce surface wear. In this study, the chemical conversion coating technique was implemented to acquire three distinct coating variations on the surface of cylindrical thrust roller bearings (CTRBs). Nanoindentation tests were conducted to analyze the mechanical features of the coatings, specifically targeting the elastic modulus and nanohardness. To evaluate the surface properties of the coatings, a 3D profilometer was employed. Moreover, the tribological behavior of the CTRBs, subsequent to the application of the coatings, was examined under conditions of dry friction and solid lubrication using a vertical friction and wear testing apparatus. A theoretical framework was established to elucidate the initial phase of transfer film spreading and determine the friction coefficient (COF). The impact of mechanical properties, surface characterization, and crystal structure of the coatings on the tribological performance, both under dry friction and polytetrafluoroethylene (PTFE) solid lubrication conditions, was thoroughly investigated. The findings revealed that, when subjected to dry friction, the dominant factor influencing the tribological performance of the coatings was surface roughness. The addition of solid lubricants can effectively improve the friction performance, resulting in a maximum reduction in bearing wear of 83.9 % and a minimum reduction of 13.0 %. By analyzing the worn surfaces and bearing vibration signals, the influence of coating characterization on the wear and anti-friction performance of solid lubricants is discussed.

The Optimal Design of the Press Roller to Improve the Winding Molding Quality of Heat Insulation.

In the heat insulation winding molding process of solid rocket motors, the pressure applied by the press roller directly affects the quality of the winding molding. Insufficient pressure can result in poor bonding quality and may cause defects. This paper aims to provide an optimal design of the press roller to improve the winding molding quality of the heat insulation. The effect of the cylindrical press roller on the pressure distribution was analyzed using the elastic foundation model and a finite element (FE) model, which was assessed by Hertz theory. Subsequently, the press roller was optimized to an elliptical concave design. The effect of the radius of the elliptical concave press roller on the pressure distribution was analyzed. A comparison of the effect of the elliptical concave press roller and the cylindrical press roller on the pressure distribution was conducted using the FE model. The results show pressure uniformity is significantly improved when the elliptical concave press roller is employed on the mandrel with the smallest radius. Additionally, the elliptical concave press roller increases the pressure at the edge of the tape, which reduces the risk of lifted edges and, thereby, improves the winding molding quality of the heat insulation.

Research on transient temperature rise characteristics of composite cylindrical roller bearings

Composite roller bearings have received extensive attention from bearing design engineers because of their good contact and running performance. According to the contact mechanical characteristics of composite cylindrical roller, a bearing heat generation power calculation model is established. Then, using the local heat source analysis method, and considering the heat conduction mode, the transient temperature solution model of bearings is established. The influence of filling ratio, radial force, angular velocity and roller numbers on the heat generation power and steady-state temperature of the bearing components is calculated and analyzed. The calculated results are in good agreement with the experimental results, which verifies the correctness of the model. The model can accurately predict the temperature distribution of bearings, providing new ideas and methods for temperature rise analysis, and laying the foundation for temperature analysis of bearings.

TFC-TFECR feature extraction and state recognition of acoustic emission signal of cylindrical roller bearing

ABSTRACT Rolling bearings are widely used in rotating machinery, such as aero-engine spindles, flying machines, wind turbines, etc. Bearing condition monitoring is of practical importance. The acoustic emission (AE) signal has impact and rapid attenuation characteristics. Most existing research on fault diagnosis is not focused on rapid attenuation characteristics. According to this characteristic, a time-frequency coherent and time-frequency energy change rate (TFC-TFECR) method is proposed to identify the AE signals of bearing faults. This paper investigates the effect of the time-frequency coherent (TFC) method on attenuation coefficient. It also focuses on the deviation of the time-frequency energy change rate of the TFC-TFECR method, which is superior to the time-frequency energy. Feature extraction of AE signals from cylindrical roller bearings is carried out through three typical states of cylindrical roller bearings. The feature values of the TFC-TFECR method are input into the SVM model, and the sparrow search algorithm optimises the SVM model. The experimental results show that the method can effectively realise the feature extraction and state recognition of the AE signals of cylindrical roller bearings, and the accuracy rate reaches 99.3827% at 600 r/min and 98.7654% at 1200 r/min. This paper provides a new method for non-destructive testing of rotating machinery bearings.

Features of hardening of the case parts made of aluminium alloys

The dependence of the hardened layer depth on the modes of superficial treatment is experimentally investigated, with the purpose of evaluation of known laws of initial linear contact of the strengthening part and the tool. The method of the definition of optimum loading on strengthening tool (the steel cylindrical roller) and its radius at static stamping is offered. The technique is examined with the reference to the case parts made of aluminum alloys.

Three-dimensional reconstruction of industrial parts from a single image

This study proposes an image-based three-dimensional (3D) vector reconstruction of industrial parts that can generate non-uniform rational B-splines (NURBS) surfaces with high fidelity and flexibility. The contributions of this study include three parts: first, a dataset of two-dimensional images is constructed for typical industrial parts, including hexagonal head bolts, cylindrical gears, shoulder rings, hexagonal nuts, and cylindrical roller bearings; second, a deep learning algorithm is developed for parameter extraction of 3D industrial parts, which can determine the final 3D parameters and pose information of the reconstructed model using two new nets, CAD-ClassNet and CAD-ReconNet; and finally, a 3D vector shape reconstruction of mechanical parts is presented to generate NURBS from the obtained shape parameters. The final reconstructed models show that the proposed approach is highly accurate, efficient, and practical.