• 제목/요약/키워드: Hearing Lubrication

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공기베어링에서의 선단압력발생에 관한 연구 (A Study on Inlet Pressure Build-up of Air-Lubricated Bearings)

  • 김성국;김경웅
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 1999년도 제29회 춘계학술대회
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    • pp.127-132
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    • 1999
  • The inlet pressure build-up at the leading edge of bearings which have discontinuous lubrication surface is analyzed theoretically. The analyses of Inlet pressure build-up is obtained by means of full Navier-stokes equations. Beam-warming method is used to solve navier-stokes equations. The results show that inlet pressure is above atmosphere pressure in front of leading edge of hearing.

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공기 혼합오일에 대한 고속 저어널 베어링 열유체 윤활 해석 (Thermohydrodynamic Bubbly Lubrication Analysis of High-Speed Journal Bearing)

  • 전상명
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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    • pp.201-211
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    • 2001
  • The influence of aerated oil on high-speed journal bearing is examined by classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of aerated oil in fluid-film bearing. Convection to the walls, mixing with supply oil and re-circulating oil, and some degree of journal misalignment are considered. The considered Parameters for the study of bubbly lubrication are oil aeration level, air bubble size, shaft misalignment and shaft speed. The results show that deliberate oil aeration can more clearly bring on the increasing load capacity under high-speed operation of plain journal hearing than previous normal speed operation. And the load capacity may be increased more by oil aeration under the conditions of shaft misalignment and the increasing speed.

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최적 베어링 윤활 그리이스의 합성과 특성연구 (A Study on Synthesis and Characteristics of The Optimum Rolling Bearing Greases)

  • 김상근;박창남;한종대;손관수
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2003년도 학술대회지
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    • pp.129-138
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    • 2003
  • Rolling bearings are classified one of the most important machine elements. The various function of bearings are greatly influenced by grease, and higher performance of rolling bearing greases is required in improve bearing lubrication. Three urea/ether oil greases with identical composition were synthesized to compare the performance of these greases according to the thickener content of grease. The typical grease physical properties were investigated. And life test of these greases was conducted by FE-9 grease life tester. The characteristics of the greases before and after life test were investigated using FT-IR, microscope, OIT and TAN meter. Large differences in the grease performance depending on the content of the thickener were observed. The grease with higher content of the hickener showed higher performance such as long life time and low TAN value. After preliminary test, twelve greases were synthesized and evaluated the performance of dropping point and OIT, then optimized two greases were selected by SSRED (Six Sigma Robust Engineering Design) using dropping point and OIT data. Characteristics of the optimized two greases were on the same level with estimated value. The optimized grease by means of OIT value showed longer grease life in comparison with optimized grease by dropping point. However two greases showed higher performance than typical urea/ether oil.

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기체분자운동론을 이용한 박막 베어링 해석 (Kinetic Theory Analysis for Thin-Film Bearings)

  • 정찬홍
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2004년도 학술대회지
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    • pp.162-170
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    • 2004
  • A kinetic theory analysis is used to study the ultra-thin gas flow field in gas slider hearings. The Boltzmann equation simplified by a collision model is solved by means of a finite difference approximation with the discrete ordinate method. Calculations are made for the flow field inside stepped and straight slider bearings. The results are compared well with those from the DSMC method. Special attention has been paid to the effect of the pressure build-up in front of a hearing, which has never been assessed before. It has been shown that the pressure build-up at the inlet is about $4.5\%$ of the operating pressure and the resulting load capacity is about $25\%$ higher for the case considered in the present study.

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자동차용 깊은홈 볼베어링의 조기파손 : 1보 - 파손기구의 규명 (Premature Failure of Deep Grooved Ball Bearing for Automobiles : Part 1 - A Failure Mechanism)

  • 현준수;박태조
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2003년도 학술대회지
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    • pp.388-394
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    • 2003
  • This paper deals with a premature failure mechanism of deep grooved ball bearing for automobiles. A close examination of used bearings revealed that the premature failure could be arose by dents on the ball. Universal testing machine with specially designed tools is used to simulate the practical dents on the ball and test bearings are assembled with dented balls and new hearing components. The endurance test results showed that the dents on the balls were printed on the races and these phenomena come to premature failure.

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