Hollow Cylindrical Roller Research Articles

Experimental and Theoretical Study on Forming Film Properties of Hollow Cylindrical Rollers

Bending deformation of a hollow cylindrical roller (HCR) was calculated by curve bending theory and slice technology. Furthermore, an elastohydrodynamic lubrication (EHL) model involving hollow rollers was established by coupling the finite line EHL model and bending deformation. Measurements of film thickness for hollow rollers were carried out by using a line-contact optical EHL test rig, and the experimental data and theoretical results agreed well with each other. For a roller with a straight-line profile, the hollow structure could reduce pressure peak at the roller ends, but the edge effect was still present. The film thickness at the ends unfortunately could not be improved by such hollow structures, unless a profile modification for the operating surface is designed.

Efficient Strain Analysis of Radially Loaded Hollow Cylindrical Roller Using Symbolic Regression

Efficient Strain Analysis of Radially Loaded Hollow Cylindrical Roller Using Symbolic Regression

Finite element contact analysis of the hollow cylindrical roller bearings

Finite element contact analysis of the hollow cylindrical roller bearings

Study on Contact Force and Vibration Characteristics of Composite Cylindrical Roller Bearing

The composite cylindrical roller is composed of a hollow cylindrical roller and a filler body and is a new type of structure roller bearing. In order to explore the influence of different parameters on the contact characteristics and vibration characteristics of bearings, finite element models of static contact, modal analysis, and harmonic response analysis of composite cylindrical roller bearings were established based on ABAQUS software. The effects of filling rate, radial force, and the number of rollers on parameters such as contact force, contact stress, and natural frequency were studied. The results show that when the filling rate of the cylindrical roller increases from 0% to 70%, the natural frequency of bearing and the peak frequency of its harmonic response decrease, the force distribution in the contact area is also more uniform, and the maximum contact stress of the roller is reduced by 29.1%; the radial force has no effect on the peak frequency of the harmonic response of the bearing, but the increase of the radial force will increase the peak value of the response displacement, and the contact force and stress of the rollers will also increase. When the number of rollers increases from 11 to 15, the natural frequency and the peak frequency of harmonic response increase, the peak displacement decreases, the contact force distribution of the rollers in the bearing area is more uniform, and the maximum contact stress of the roller is reduced by 21.1%. The research result can provide a theoretical reference for the structural optimization and engineering application of elastic composite cylindrical roller bearings.

Mechanical Properties of Coupled Bending and Contact to Hollow Cylindrical Roller Contacts

A numerical analysis model of the hollow cylindrical roller is established by coupling the bending of the curved beam and elastic half-space contact theory. Slicing technology is applied to solve the bending deformation of every circle slice. Discrete fast Fourier transform (DC-FFT) and a conjugate gradient method are employed to solve the contact deformation and contact pressure, considering the bending effect in both radial and axial directions. The influence of hollowness on deformation, contact pressure, stiffness, and strain energy for a straight roller contacting a flat plane is studied using the numerical model. The results reveal that with the increase of hollowness, the contact pressure decreases at the end, the edge effect weakens apparently, the contact width and contact deformation increase slightly in the middle part, and the stiffness decreases. The bending deformation and strain energy increase sharply as the hollowness reaches 60%. What's more, the profile of the contact region gradually changes from "outer convex" to "inner concave" at the end, which is also validated by photographing the shapes of the static contact region under various hollowness conditions using an optical interference test.

Contact Mechanics Response of Composite Cylindrical Roller Bearings Based on FEM

In response to the increasing demand for the working performance of cylindrical rollers in the industry, in this paper, PTFE and hollow cylindrical roller bearings are combined and improved to form composite cylindrical roller bearings. Establish a numerical calculation model of composite cylindrical roller bearings, which compares with hollow cylindrical rollers, and analyze the influence of filling degree and magnitude of load on various parameters of composite cylindrical rollers. The result shows that the mechanical properties of composite cylindrical roller bearings are better than hollow cylindrical rollers. It can significantly improve the bending stress of the inner wall of the roller; the greater the filling degree, the less obvious the stress concentration phenomenon at the two ends of the roller contacting the bus bar, and the higher the equivalent stress value on the inner wall of the roller. The optimal filling degree is affected by the load, and the optimal filling degree is different under different load conditions. The greater the working load, the more obvious the stress concentration at both ends of the composite cylindrical roller.

Experimental investigation of an elastic contact between a layered cylindrical hollow roller and flat plate

A novel roller design, a layered cylindrical hollow roller is suggested for roller type bearings, in which a small hollow cylinder is embedded into another large hollow cylinder with the same percentage of hollowness. This paper deals with a theoretical and experimental investigation for the cylinder-on-flat type contact interaction. In theoretical calculation Hertz theory is used for half contact width calculation. While experimental analysis is carried out with the help of “footprint method” for analyzing a real contact area between elastic solids. In footprint method the indentation of the roller on flat plate with regard to the applied load is measured. The theoretical data is compared for the validation of experimental technique. The test results are very close and similar with the theoretical data. With the help of this experimental technique, contact analysis between hollow roller and flat plate and between layered cylindrical hollow roller and flat plate have been carried out. Finally, in this work, experimentally evaluated contact width values are compared between hollow roller and layered cylindrical hollow roller. The experimental results suggested that the layered cylindrical hollow roller has larger contact width as compared to hollow roller with the same outside dimension and hollowness under same compressive loading conditions.

An Analytical Dynamic Model of a Hollow Cylindrical Roller Bearing

Hollow cylindrical roller bearings (HCRBs) have obtained much attention from design engineers in bearing industries since they can perform better than solid cylindrical roller bearings (SCRBs) in centrifugal forces, contact stiffness, cooling ability, fatigue life, etc. In this study, an analytical dynamic model of a lubricated HCRB is presented to analyze the influences of the radial load, the shaft speed, and the hollowness percentage of the roller on the bearing vibrations, which cannot be formulated by the methods in the reported literature. Both the support stiffness of the shaft and the roller mass are formulated in the presented dynamic model. The hollow hole in the roller is modeled as a uniform one. Numerical results show that the hollowness percentage of the roller has a great influence on the vibrations of the roller and the inner race of the HCRB. Moreover, the vibrations of the components of the HCRB are not only determined by the hollowness percentage of the roller, but also depended on the external radial load and shaft speed. Therefore, during the design process for the hollowness percentage of the roller, the influences of the radial load and the shaft speed on the vibrations of the bearing components should be considered, except for the fatigue life. The results show that this work can give a new dynamic method for analyzing the vibrations of the HCRBs. Moreover, it can give some guidance for the design method for the HCRBs.

Development of a mathematical model to determine optimum hollowness in layered cylindrical hollow rolling element using FE analysis

PurposeThe purpose of this paper is to develop a mathematical model to determine optimum hollowness of a layered cylindrical hollow rolling element when it contacts with a flat plate.Design/methodology/approachIn this work, finite element analysis (FEA) is carried out for different hollowness percentages ranging from 10 to 90 layered cylindrical hollow rolling elements corresponding to five standard NU 22 series bearings, i.e. 2206, 2210, 2215, 2220 and 2224. An experimental investigation is carried out for the NU 2206-layered cylindrical hollow roller bearing (LCHRB) at optimum hollowness under static loading condition.FindingsDifferent parameters, such as bending stress (von Mises stress at the bore of the roller), von Mises stress, contact pressure and deflection in loaded contact are presented here.Originality/valueThe value of this research work is the development of a generalized solution that can be used to find the exact value of optimum hollowness for the layered cylindrical hollow rolling element, which is dependent on the yield strength of the material and the geometry of the roller under static loading condition. A static load test rig is designed to observe the load carrying capacity of the LCHRB as compared to the hollow cylindrical roller bearing.

Extending Hertz equation for an elastic contact between a layered cylindrical hollow roller and flat plate through an experimental technique

PurposeThe purpose of this paper is to extend the Hertz equation for the contact interaction between a layered cylindrical hollow roller and a flat plate through an experimental technique.Design/methodology/approachIn this work, an experimental investigation is carried out for an elastic contact between layered cylindrical hollow rollers of different hollowness, ranging from 30 to 75 per cent hollowness and a flat plate. The footprint method was used for the evaluation of the contact width corresponding to the applied load.FindingsThe contact width for the layered cylindrical hollow roller was evaluated and the Hertz equation was extended on the basis of the experimental results.Originality/valueThe value of this research work is the development of an extended Hertz equation for a cylinder-on-plate configuration for a new kind of cylindrical roller.

A finite element analysis of an elastic contact between a layered cylindrical hollow roller and flat contact

PurposeThe purpose of this paper is to present a finite element analysis (FEA) which shows the comparison between a layered cylindrical hollow roller bearing and hollow roller bearing.Design/methodology/approachIn this work, FEA is carried out to solve the elastic contact between a layered cylindrical hollow roller and flat contact for different hollowness percentages ranging from 10 to 80 per cent. Graphical solution is developed to determine the optimum hollowness of a cylindrical roller bearing for which induced bending stress should be within endurance limit of the material.FindingsDifferent parameters such as von Mises stress, contact pressure, contact width and deformation are shown here.Originality/valueThe value of this research work is the calculation of contact width and other parameters using FEA for layered cylindrical hollow roller bearing.

Current investigation in layered cylindrical hollow roller bearing using elastic finite element analysis

A novel roller form, a layered cylindrical hollow roller is proposed for roller type bearings; with a view to reduce bending stresses occurred in hollow cylindrical roller bearing. The new type of roller has reduced weight, better radial stiffness, higher operating speeds and lower operating temperatures compared to conventional solid roller. Recently the Finite Element Analysis (FEA) has been successfully used to evaluate contact problems for roller bearings. Investigations have been made for layered cylindrical hollow rollers in pure normal loading. Different hollowness percentages ranging from 0% to 80% have been analysed in FEA software to find the optimum percentage hollowness which gives minimum stress and finally longest fatigue life.

Analysis of bearings behaviour with cylindrical rollers with variable center of gravity

This paper consists in analysis of the contact stress and deformations appeared to the cylindrical rollers with variable center of gravity who equips large bearings, with finite elements method. Also it proposed an innovative model of lubrication system mounts in the hollow cylindrical rollers of the large bearings where it is stored the lubricant who is driven to the raceways through holes fitted with closing/opening systems made in the cover, controlled by a command system, monitoring and control, equipped with temperature sensors and wireless command. Elimination of lubricant, in stages, leads to changes in position of center of gravity of roller, thus to change its behavior in functioning. Comparison of deformations occurred in cylindrical rollers, solid, with hollowness, and with variable center of gravity, allow favorable conclusions, on the implementation of the proposed lubrication system.

Mechanical performance analysis of hollow cylindrical roller bearing of cone bit by FEM

Abstract Bearings are key components of cone bit, thus its rapid failure is a major cause of leading to lower life of the bit. To improve the bearing performance and prolong working life, contact mechanics of hollow cylindrical roller bearing of cone bit was simulated. Effects of hollow size, drilling pressure, friction coefficient and fitting clearance on mechanics performance of the bearing were studied. The results show that the maximum equivalent stress of the hollow cylindrical roller bearing appears on the claw journal, and the maximum contact stress appears on the contact pair of the hollow roller. Besides, hollow sizes have a greater impact on the equivalent stress and contact stress of the cylindrical roller, while the influence on the stress of the cone and claw journal is relatively small. With the increasing of the drilling pressure and fitting clearance, equivalent stress and contact stress of bearing parts increase. The friction coefficient has little impact on mechanical performance of the bearing. As the 121/4SWPI517 type hollow cylindrical roller bearing of cone bit an example, the optimal hollow size is 55%, the drilling pressure is 140 kN and the fitting clearance is 0–0.02 mm.

원통형 중공롤러의 응력 및 변형거동에 관한 유한요소해석

본 연구에서는 원통형 중공롤러의 응력과 변형거동 안전성을 FEM으로 해석하고, 그 계산결과를 기초로 과도 설계 여부를 고찰하였다. 중공롤러의 강도에 관련된 응력해석 결과에 따르면, 중공롤러를 지지하는 베어링을 설치한 인근에서 발생한 최대응력 39.8MPa은 구조용 강재의 항복강도인 250MPa 대비 15.9% 수준으로 과도한 설계로 평가될 수 있다. 또한, 원통형 중공롤러의 전체 길이 대비 중간 스팬부에서 발생한 최대 변위량 0.032mm는 중공롤러의 전체 길이와 두께에 견주어 볼 때 충분히 안전하다할 수 있다. 결국, 강도와 변형거동에 대한 FEM 해석결과에 의하면, 현재의 원통형 중공롤러 FEM 해석모델은 과도하게 설계되었다고 분석된다. The stress and deformation behavior safeties of cylindrical hollow rollers have been analyzed by the finite element method, and investigated for over design capability based on the computed results. According to the stress analysis result which is related to the strength of a hollow roller, the maximum stress of 39.8MPa in which is operated near the bearing for supporting a hollow roller structure is overestimated design as 15.9% level compared with a yield strength, 250MPa of a steel material. And the maximum deformation of 0.032mm in which is operated at the middle span of a total length of cylindrical hollow rollers is very small and sufficiently safe compared with a total length and a thickness of a hollow roller. Thus, the FEM computed results for a stress and deformation indicate that a current FEM analysis model of cylindrical hollow rollers is over designed.

Study on the Performance of Wollastonite Modified PTFE Composite Material

In the research, Polytetrafluoroethene (PTFE) is applied in a newly elastic composite cylindrical roller bearing, i.e. PTFE is modified into the traditional hollow cylindrical roller bearing so as to improve the vibration, wearing properties and life span of the roller bearing. The results show that bearing capacity of the same dimension of WF/PTFE composite materials is higher than that of WP/PTFE composite materials. Small dimension of WF-PTFE composite materials has the best wearing properties under light load conditions; large dimension of WF-PTFE composite materials has better bearing capacity and wearing properties than small dimension of WF filler under heavy load conditions. Compare to traditional method, Rolling stress improves by filler PTFE materials using our method reduces by 17.1% under light load conditions and reduces by 27.7% under heavy load conditions. The research provides basis for the modified material of the elastic composite cylindrical roller bearing.

와이어 소 머신용 중공롤러의 변위량과 응력해석에 관한 연구

본 연구에서는 원통형 중공롤러를 갖는 와이어 소 머신에 대한 변위와 응력강도 안전성 해석결과를 제시하고 있다. 유한요소법을 사용하여 세 개의 튜브 사이에 Y형상의 편위형 컬럼과 수직형 컬럼을 설치한 중공롤러에서 변형거동과 응력강도 안전성을 높인 중공롤러를 개발하고자 한다. 동일한 직경과 길이를 갖지만, 중량을 달리하는 중공롤러 모델에서 Y 형상의 편위형 및 수직형 중공롤러에 작용하는 변위거동 안전성은 중공롤러의 전체길이에 의해 더 많은 영향을 받는 것으로 나타는데, 이것은 중공롤러의 굽힘 모멘트와 밀접한 관련이 있다. 그러나, 중공롤러의 응력강도는 중량 차이가 크지 않을 경우 절단면의 형상에 의해 더 큰 영향을 받는 것으로 나타났다. 따라서, 중공롤러의 강도안전성을 높이고, 총중량을 낮추기 위해서는 Y형상을 갖는 중공롤러를 사용하는 것이 바람직함을 알 수 있다. In this paper, the displacement and stress strength safeties have been presented for cylindrical hollow rollers of a wire saw machine. Using the finite element method, the hollow roller with Y-shaped shift and vertical columns between three tubes has been developed to analyze the displacement behavior and stress strength safeties. For the same diameter and length of hollow roller models with a different weight, the displacement behavior safety of Y-shaped shift column and vertical column models is heavily depending on the total length of a hollow roller, which is closely related to the bending moment of a hollow roller structure. But, the stress strength of a hollow roller is more influenced by the cross sectional area of a hollow roller for the similar weight. Thus, this paper recommends Y-shaped hollow roller for increasing the roller strength safety and decreasing a total roller weight.

원통형 중공롤러의 변형거동 안전성에 관한 연구

본 연구에서는 원통형 중공롤러의 변위거동 안전성에 대한 해석적 연구를 수행하였다. 세 개의 튜브들 사이에 Y형상을 갖는 컬럼 구조물을 설치한 중공롤러를 개발하여 유한요소법으로 변형거동 안전성을 해석하였다. 동일한 크기와 중량을 갖는 두 개의 중공롤러 모델에 대한 해석결과에 의하면, 기존의 중공롤러는 세 개의 튜브 사이에 새로이 설계된 Y형상을 갖는 컬럼을 설치한 중공롤러에 비해 4~6.6% 낮은 변형거동 안전성을 보여주고 있다. 따라서 본 연구에서는 중공롤러의 강도 안전성을 높이고, 전체적인 중량을 낮춰 소비되는 전기에너지를 줄이기 위해서는 Y형상 컬럼을 설치한 새로운 중공롤러를 사용하는 것이 바람직함을 알 수 있다. This paper presents an analytical study on the displacement behavior safety of cylindrical hollow rollers. Using the finite element method, the hollow roller with Y-shaped column structures between three tubes has been developed to analyze the displacement behavior safety. For the same dimension and weight of two hollow roller models, the displacement behavior safety of a typical hollow roller is lower 4~6.6% than that of the newly designed hollow roller with Y-shaped column structures between three tubes. Thus, this paper recommends Y-shaped hollow roller for increasing the roller strength safety and decreasing a total roller weight, which may save a consuming electrical energy.

Theoretical Research on the Radial Stiffness of Pre-Loaded Hollow Cylindrical Roller Bearings

For solving the problems of classical mechanics on the stiffness of hollow cylindrical roller bearings, the radial stiffness of pre-loaded hollow cylindrical roller bearings is analyzed with finite element method and the elastic deformation of inner and outer rings is also taken into account. The effects of load, interference magnitude, and hollow ratio on the bearing stiffness are researched fatherly. The results show that the bearing stiffness correlates not only with the interference magnitude and hollow ratio, but also with load, which offers the references for designing and using the pre-loaded hollow cylindrical roller bearings.

Predicting optimum hollowness of normally loaded cylindrical rollers using finite element analysis

Fatigue life investigations have been made for hollow rollers in pure normal loading. Different hollowness percentages between 20 and 80% have been tested to find the optimum percentage hollowness that gives the longest fatigue life. Two main models were built for this purpose: model 1 with two identically sized rollers and model 2 with two non-identically sized rollers. In each model, two cases have been studied: when both rollers are hollow and when one roller is hollow while the other one is solid. The Ioannides–Harris (IH) theory was used to calculate the relative fatigue life of the hollow rollers with respect to solid rollers under the same loading. Investigations have been made for five different materials: CVD 52100, carburised steel, VIMVAR M50, M50NiL and induction hardened steel. The finite element package ABAQUS has been used to study the stress and deformations in the loaded rollers. In general, the optimum hollowness percentage with the longest fatigue life ranges between 60 and 70% based on the kind of the material, whether the rollers are of the same or different size and whether one or both rollers are hollow. Using the IH theory for fatigue life calculation resulted in having infinite fatigue life for those rollers made of induction hardened steel that relatively has high fatigue limit value. Rollers in the optimum range are flexible enough to get the best redistribution of stress in the contact zone. For models of a hollow cylindrical roller in contact with a solid roller, the optimum hollowness is around 70%. When both cylindrical rollers are hollow, the optimum hollowness decreases between 60 and 65%. At the optimum hollowness, small differences in the fatigue life have been found between models of one hollow roller and models of two hollow rollers, even though having both hollow rollers means less weight, thus saving more material and more stability for the system.