• Title/Summary/Keyword: Bearing race

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Heat Generation Characteristics of Ball Bearing for Operating Conditions (볼 베어링의 운전조건에 따른 발열 특성)

  • 장윤석;나희형;임윤철
    • Tribology and Lubricants
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    • v.13 no.4
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    • pp.26-32
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    • 1997
  • The heat generation of the angular contact and the deep groove ball bearing is studied experimentally and numerically. The temperature variation of the inner and outer races and the temperature increase distribution are measured for the shaft rotational speeds, preloads, viscosities of the lubricant and lubrication methods. The measured temperature distributions are used as the input data of the numerical simulation to estimate the heat generation rate at the bearing. The temperatures of the inner and outer race increase more rapidly and approach faster to their steady values as the rotational speed increases. The optimal viscosity of the oil to minimize the heat generation is 8~10 cSt at 4$0^{\circ}C$ when the oil-air lubrication method is adopted. The heat generation of the bearing increases with the rotational speed and depends more on the lubrication method than on the preload variation.

Evaluation of Boundary Conditions for Structural Analysis of Wheel Bearing Units (Wheel Bearing Unit의 구조해석을 위한 경계조건 설정에 관한 연구)

  • 김기훈;유영면;임종순;현준수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.6
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    • pp.230-237
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    • 2000
  • The wheel bearing in vehicles has been improved to unit module by joining a bearing to a hub in order to achieve weight reduction and easy assembly. Currently, the contact force between a raceway and balls of a bearing is applied as the external force in order to analyse the structure of the unit type bearings. In this paper, simplified boundary conditions are discussed for structure analysis of wheel bearing unit. From the procedure, the contact conditions of balls and race in wheel bearing unit are considered as equivalent non-linear spring elements. The end node of a spring element is constrained in displacement. And the external force of boundary conditions is applied at the contact point between tire and road. For the evaluation of this analysis, its results for the force of spring elements are compared with contact forces of calculated results. and also maximum equivalent stresses of analysis are compared with results of test at the flange of inner ring. The analysis results with proposed boundary conditions are more accurate than results from analysis which is generally used.

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Optimum Crowning Quantity Calculations of the Tapered Roller Bearing which Considers Tilting (Tilting을 고려한 테이퍼롤러 베어링의 최적 크라우닝량 계산)

  • Bae, Jong-Yup;Lee, Sang-Don;Doh, Byoung-Kwon;Cho, Yong-Joo
    • Tribology and Lubricants
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    • v.25 no.6
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    • pp.427-431
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    • 2009
  • When a bearing roller is in contact with race ways. excessive pressure peaks occur at the ends of the contact region. They are called edge loading. In this study, a method to determinate crowning quantity of the tapered roller bearing which considers tilting. This method is based on contact analysis.

A Study on Heat Treatment for Improving Cold Forgeability of a Bearing Steel, SUJ2 (베어링강 SUJ2의 냉간 단조성 향상을 위한 열처리에 관한 연구)

  • Kim, Hae-Ji
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.8 no.1
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    • pp.24-30
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    • 2009
  • In this paper, the effect of heat treatment on forgeability is investigated and an improved heat treatment cycle is proposed for the bearing steel, SUJ2. An application example of a bearing inner race cold forging, which has small cracks in the bottom after backward extrusion and piercing, is found from a cold forging industry. The process is evaluated by finite element analysis and several heat treatment cycles are examined in order to propose an improved heat treatment cycle. The effect of heat treatment on material hardness and tool life, dimensional accuracy and forming load is revealed through experiment.

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NRRO Analysis of HDD Ball Bearings with Geometric Imperfections (기하학적 형상오차를 갖는 정보저장기기용 볼베어링의 NRRO 해석)

  • 김영철;최상규;윤기찬
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.810-816
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    • 2001
  • In this paper, we theoretically analyzed the NRRO(the non-repeatable run-out) of a ball bearing with geometric imperfection. The quasi-static and dynamic analysis of a ball bearing was performed to calculate the displacement of shaft center caused by the form errors while the shaft is rotating. From consideration of the generating mechanism of NRRO, it is found that the waviness of one ball generates vibrations with nf$\sub$b/${\pm}$f$\sub$c/(where n is odd) components. Also it is confirmed that the outer race waviness of the order n = jZ${\pm}$1 generates vibration with jZf$\sub$c/ components. The form errors of ball bearing elements were precisely measured and NRRO of a ball bearing was calculated using the measured data. It is concluded that the ball bearings must has large ball number and small ball diameter to obtain low NRRO.

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A New Approach Increasing the Rotational Accuracy of Ball- Bearing Spindle by Using Proper Bearing Positioning

  • Yegor. A.;Lee, Choon-Man;Chung, Won-Jee
    • International Journal of Precision Engineering and Manufacturing
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    • v.4 no.5
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    • pp.15-21
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    • 2003
  • In order to improve the quality of a spindle unit it is important to increase its rotational accuracy. The rotational accuracy of a spindle unit can be defined as the stability or immobility of its spindle axis while rotating. Spindle rotation in the rolling bearings causes the disturbing influence, which leads to the oscillation of a rotation axis. The purpose of this study is to investigate the oscillation sources and find a way to decrease the runout without additional expenses. The main source of oscillation is the interaction between rolling bodies and ring races. The first oscillation source was the out-of-shape imperfection of inner bearing ring. The mutual compensation of oscillation by proper rings orientation was proposed, which sometimes allow to decrease the radial runout of spindle rotation axis by approximate 40% down. Also the outer ring harmonics were explored as the second oscillation source. The analysis shows the dependency between the number of rolling bodies and the outer ring race harmonics. The conclusion on the orientation of bearing cages and the bearing rings was made, which makes possible to obtain the optimal variant of their mounting in the spindle unit when the rotational accuracy of the spindle is maximal, and the spindle runout considerably less.

Improving Stability of Motor Generator Set of the Power Supply System for CEDM in Korean Standard Nuclear Power Plants (한국표준형 원전 제어봉구동장치 전원공급계통의 전동발전기 세트 안정성 개선)

  • Choi, Il Young;Kim, Jin Weon
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.12 no.1
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    • pp.49-55
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    • 2016
  • This paper analyzed a root cause of abnormality in the temperature and vibration at generator-side bearing of motor generator set (MG Set), which is a power supply system to control element drive mechanism (CEDM) of nuclear power plants (NPPs), and modified the design of roller-type and sealing method to improve the abnormalities. From the inspection of MG Set and analysis of temperature variation during service, it was found that the abnormal temperature transition was basically associated with original design of generator-side bearing, whose roller was axially restrained by inner race, and that the abnormal vibration level was caused by inserting small chips of cage and V-ring, which were generated due to the abnormal temperature transition at roller bearing. Type of bearing and sealing method were modified based on these analyses. The temperature and vibration level measured at roller bearing showed that the modifications clearly improved the operational stability of MG Set.

Stator Current Processing-Based Technique for Bearing Damage Detection in Induction Motors

  • Hong, Won-Pyo;Yoon, Chung-Sup;Kim, Dong-Hwa
    • 제어로봇시스템학회:학술대회논문집
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    • 2005.06a
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    • pp.1439-1444
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    • 2005
  • Induction motors are the most commonly used electrical drives because they are rugged, mechanically simple, adaptable to widely different operating conditions, and simple to control. The most common faults in squirrel-cage induction motors are bearing, stator and rotor faults. Surveys conducted by the IEEE and EPRI show that the most common fault in induction motor is bearing failure (${\sim}$40% of failure). Thence, this paper addresses experimental results for diagnosing faults with different rolling element bearing damage via motor current spectral analysis. Rolling element bearings generally consist of two rings, an inner and outer, between which a set of balls or rollers rotate in raceways. We set the experimental test bed to detect the rolling-element bearing misalignment of 3 type induction motors with normal condition bearing system, shaft deflection system by external force and a hole drilled through the outer race of the shaft end bearing of the four pole test motor. This paper takes the initial step of investigating the efficacy of current monitoring for bearing fault detection by incipient bearing failure. The failure modes are reviewed and the characteristics of bearing frequency associated with the physical construction of the bearings are defined. The effects on the stator current spectrum are described and related frequencies are also determined. This is an important result in the formulation of a fault detection scheme that monitors the stator currents. We utilized the FFT, Wavelet analysis and averaging signal pattern by inner product tool to analyze stator current components. The test results clearly illustrate that the stator signature can be used to identify the presence of a bearing fault.

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Structural Stability Evaluation for Special Vehicle Slewing Bearing using Finite Element Analysis (유한요소해석을 통한 특수차량용 선회베어링의 구조 안전성 평가)

  • Seo, Hyun-Soo;Lee, Ho-Jun;An, Tae-Su
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.1
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    • pp.511-519
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    • 2021
  • Slewing bearing is applied to the transmission of rotational power of the body and turret in a special vehicle for anti-aircraft weapons that overcomes the enemy flight system approaching at low altitudes with rapid response fire. When the turret load and impact load generated when shooting are combined in performing the combat mission of a special vehicle, structural stability must be secured to achieve a successful function. Among the components of the slewing bearing, the stability of the components against the complex loads acting by the turret drive and shooting was evaluated by considering the shape and material characteristics of the ring-gear, roller, and wire-race. As a research method for stability evaluation, based on engineering theory, the strength characteristics of the components were examined by numerical calculations. Finite element analysis was performed on components using the ANSYS analysis program. The results of theoretical analysis and the results of finite element analysis were very similar. A structural stability evaluation for the slewing bearing, which was performed mainly on the analysis, confirmed that the design strength of the slewing bearing determined in the preliminary design in the early stage of localization development was sufficient.

Tribology Characteristics of Bearing Steel (STB2) with Pattern Shape (Pattern 형상이 적용된 베어링 강(STB2)의 트라이볼러지 특성)

  • Song, S.O.;Jang, T.H.;Bae, M.K.;Kim, T.G.
    • Journal of the Korean Society for Heat Treatment
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    • v.34 no.3
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    • pp.130-136
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    • 2021
  • With the development of the industry, bearings that require higher durability and efficiency are required, and various methods to reduce friction and wear of bearings are being studied. In this study, a wear test was conducted for STB2, a bearing steel material, by machining a micro-line pattern on the race surface of the bearing by machining. The pattern pitch of the specimens was processed to 40㎛, 80㎛, and 150㎛, and the coefficient of friction characteristics were investigated for the unpatterned specimen and the specimen with a DLC thin film deposited on the surface. As a result of the wear test, the pattern pitch showed the smallest coefficient of friction at 40㎛, and it was confirmed that the smaller the pattern pitch, the better the tribology characteristics.