• 제목/요약/키워드: Bearing

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세라믹 볼베어링의 특성해석에 관한 연구 (A Study on the Characteristics of Ceramic Ball Bearing)

  • 김완두;한동철
    • Tribology and Lubricants
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    • 제8권2호
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    • pp.64-72
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    • 1992
  • The recent trends of rotating machinery demand high speed and high temperature operation, and the bearing with new material is required to be developed. Ceramic, especially silicon nitride, have been receiving attention as alternative material to conventional bearing steel. Ceramic ball bearing offers major performance advantages over steel bearing, for instance, high speed, maginal lubrication, high temperature, improved corrosion resistance and nonmagnetic capabilities etc.. In this paper, the mechanical characteristics of ceramic ball bearing (hybrid ceramic bearing and all ceramic bearing) were investigated, and the characteristics of ceramic bearing were compared with that of steel bearing. Deep groove ball bearing 6208 was taken the object of analysis. The main results of analysis were followings: the radial stiffness of hybrid and all ceramic bearing were 112% and 130% that of steel bearing, and the axial stiffness of all ceramic bearing was 110% that of steel bearing. According as rotating speed was up, the ball load, the contact angle, the contact stress and the spin-to-roll ratio between ball and raceway of ceramic bearing were far smaller than these of steel bearing. And there was not a significant difference between the minimum film thickness of ceramic bearing and steel bearing. It is expected that this research is contributed to enhanced fundamental technology for the practical applications of ceramic ball bearing.

그루브를 가진 함유소결베어링의 마찰 및 전기적 특성 (Friction and Electrical Characteristics of Oil-impregnated Sintered-Metal Bearing with Grooves)

  • 정광섭;김병주;송무석;이영제
    • Tribology and Lubricants
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    • 제13권3호
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    • pp.108-114
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    • 1997
  • The electrical and frictional properties of new sintered-metal bearing (S-bearing) with varying loads and speeds were measured. Also those were compared with the same products(J-bearing) made in Japan and the conventionally used ball bearing. The test results show that the frictional values of S-bearing are less than those of J-bearing, and that S-bearing operates in full-hydrodynamic lubrication regime. The values of rating current, starting time and jitter reveal that S-bearing is superior to J-bearing as well as ball bearing.

공기윤활 웨이브 저어널 베어링의 부하 특성에 관한 연구 (A Study on the Load Characteristics of Air-Lublicated Hydrodynamic Wave Journal Bearing)

  • 조성욱;임윤철
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 1999년도 제29회 춘계학술대회
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    • pp.156-161
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    • 1999
  • new bearing concept, the wave journal bearing, has been developed to improve the static and dynamic performances of an air-lubricated hydrodynamic journal bearing. This concept features waves on bearing surface. In this study, we present the solution of the compressible Reynolds equation valid for arbitrary Knudsen numbers. Straight wave journal bearing is investigated numerically. The performances of straight wave bearing are compared to the plain journal bearing over relatively wide range of bearing number and eccentricity. The wave journal bearing offers better stability than the plain journal bearing under a13 bearing numbers covered in this study. The bearing load and stability characteristics are dependent on the geometric parameters such as the amplitude and the starting point of the wave relative to the applied load. Under the condition of Knudsen number)0.01, we can not ignore the effect of slip for journal bearing.

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공기윤활 웨이브 저어널 베어링의 부하 특성에 관한 연구 (A Study on the Lond Characteristics of Air-Lublicated Hydrodynamic Wave Journal Bearing)

  • 조성욱;임윤철
    • Tribology and Lubricants
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    • 제17권1호
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    • pp.28-32
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    • 2001
  • A new bearing concept, the wave journal bearing, has been developed to improve the static and dynamic performances of an air-lubricated hydrodynamic journal bearing. This concept features waves on bearing surface. In this study, we present the solution of the compressible Reynolds equation valid for arbitrary Knudsen numbers. Straight wave journal bearing is investigated numerically. The performances of straight wave bearing are compared to the plain journal bearing over relatively wide range of bearing number and eccentricity. The wave journal bearing offers better stability than the plain journal bearing under all bearing numbers covered in this study. The bearing load and stability characteristics are dependent on the geometric parameters such as the amplitude and the starting point of the wave relative to the applied load. Under the condition of Knudsen number>0.01, we can not ignore the effect of slip for Journal bearing.

축계 진동 저감을 위한 수직형 안내 베어링의 최적 설계 (An Optimal Design of a Vertical Guide Bearing for Vibration Reduction)

  • 하현천;박철현;김형자
    • 동력기계공학회지
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    • 제5권3호
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    • pp.64-72
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    • 2001
  • This paper describes an optimal design technology in a segment type vertical guide bearing for vertical rotating machinery. Segment type vertical guide bearings have widely used for vertical rotating machinery, however bearing problems, such as excessive vibration and temperature rise, frequently take place in the actual machine. Such excessive vibration magnitude and/or abnormal bearing metal temperature rise result in serious damage and economic losses. Thus the segment type vertical guide bearing should be designed to get optimal characteristics in order to maintain stable operation without bearing failure due to abnormal vibration and/or abnormal bearing metal temperature. The preload ratio is the most important parameter in designing the segment type vertical guide bearing. Because adjustment of the bearing preload by changing the bearing clearance could easily control both the bearing stiffness and the cooling effect. In the paper, the influence of the preload effects on the bearing metal temperature and the bearing stiffness has been investigated both theoretically and experimentally in order to find out an optimum preload ratio. Results show that the segment type vertical guide bearing has an optimum preload ratio at which the bearing stiffness reaches a masimum value while the bearing metal temperature is minimized.

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공기 정압 베어링에서 열의 영향에 따른 베어링 특성에 관한 연구 (A Study on the Bearing Characteristics of Air Bearing System According to the Thermal Effects)

  • 이종렬;김보언;안지훈;이득우
    • Tribology and Lubricants
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    • 제17권1호
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    • pp.10-15
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    • 2001
  • Generally, it is said that the heat generation of air bearing is negligible. But the air bearing using at the built-in spindle is different from the general air bearing itself because of the thermal effects from the spindle motor and high-speed conditions. In this paper, in order to analysis the characteristics of air bearing by the heat, We made easy -heating-bearing-system (EHBS) and hard-heating-bearing-system (HHBS) and could identify the changes between the two bearing systems from the experiments and simulation. When spindle system reached at thermal steady-state, the changes means that the stiffness of air bearing becomes change due to the clearance change between bearing and journal. It is shown that the temperature rise and thermal effects to cause the thormal expansions have to be considered when designing air spindle system.

The Numerical Analysis of Spindle Motor Bearing Composed of Herringbone Groove Journal and Spiral Groove Thrust Bearing

  • Oh, Sang-Man;Rhim, Yoon-Chul
    • KSTLE International Journal
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    • 제2권2호
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    • pp.93-102
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    • 2001
  • Ball bearings have been widely used for the spindle motor bearing in various kinds of information storage devices. Recently many researchers have been trying to replace ball bearings with fluid film bearings because of their superior NRRO(non-repeatable runout) characteristics. In this study, a numerical analysis has been conducted for the complicate bearing system composed of herringbone groove journal bearing and spiral groove thrust bearing for the spindle motor of the information storage device. At first, spindle motor bearing is modeled as journal bearing part and thrust bearing part separately, and then observed various influences of geometric parameters. Previous studies had considered only the translational motion of the journal bearing. However, this study takes the additional 2-degree of freedom rotation into consideration to attempt to describe the real motion of the spindle bearing. As a result, rotational stiffness coefficients and rotational damping coefficients are obtained. In addition, a spindle bearing system made up of four bearings is modeled and interpreted at once and coefficients of dynamic characteristics of each bearing are obtained. Finally, an eigen analysis of bearing system is made with these results. Through this analysis, it is possible to estimate an unstable condition of the system for given geometric parameters and to propose a method which is able to avoid the unstable condition by a proper adjustment of geometric parameters.

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스트레인 게이지를 이용한 선박용 추진 축계의 베어링 반력 측정에 관한 연구 (A Study on the Measurement and Analysis of Bearing Reaction Forces of Marine Propulsion Shafting System using Strain-Gauge)

  • 김철우;이용진;조권회;김의간
    • Journal of Advanced Marine Engineering and Technology
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    • 제32권1호
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    • pp.33-41
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    • 2008
  • Bearing damages by shaft misalignment have frequently been happened in marine ships. Specially. after stern tube bearing damage and failure for large crude oil carriers have been reported several times. However. the bearing reaction of the after stern tube bearing cannot be measured by jack-up test due to the hull structure condition. Therefore, when the jack-up test is used for the bearing reaction measurements, the bearing reaction for the after stern tube bearing obtained from the theoretical calculation method have to be used. In this paper, the shaft alignment on the large oil crude carrier is theoretically calculated and the differences between the calculated and actual installed bearing reaction values are compared. The bearing reactions for forward stern tube bearing and intermediate bearing are calculated by the simple formula using the strain gauge bending moments obtained from the measurements. Their reliability is confirmed by comparing the bearing reactions from jack-up test and the bearing reaction for after stern tube bearing is calculated by the same test. Also, the bearing reactions on the after stern tube bearing, forward stern tube bearing and intermediate shaft bearing under all operating conditions are calculated by using the bending moments obtained from the measurements and it is confirmed that the differences of the bearing reaction for all operating conditions are caused from hull deflection. The results of this study should prove useful for the future projects of the alignment calculation including the hull deflection effectiveness.

전자석 바이어스 Diskless반경방향-축방향 일체형 자기 베어링 해석 (Analysis of an Electromagnet Biased Diskless Integrated Radial and Axial Magnetic Bearing)

  • 나언주
    • 한국소음진동공학회논문집
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    • 제22권10호
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    • pp.959-967
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    • 2012
  • The theory for a new electromagnetically biased diskless combined radial and axial magnetic bearing is developed. A typical magnetic bearing system is composed of two radial magnetic bearings and an axial magnetic bearing. The axial magnetic bearing with a large axial disk usually limits rotor dynamic performance and makes assembling and disassembling difficult for maintenance work. This paper proposes a novel electromagnet biased integrated radial-axial magnetic bearing without axial disk. This integrated magnetic bearing uses two axial coils to provide the bias flux to the radial and axial air gaps of the combined bearing. The axial magnetic bearing unit in this combined magnetic bearing utilizes reluctance forces developed in the non-uniform air gaps such that the axial disk can be removed from the bearing unit. The 4-pole homopolar type radial magnetic bearing unit is also designed and analyzed. Three dimensional finite element model for the bearing is also developed and analyzed to illustrate the diskless combined magnetic bearing.

수직축형 플라이휠 시스템을 위한 초전도 하이브리드 베어링의 설계 (Design of Hybrid Superconductor Bearing Set for a Flywheel System with Vertical Axis)

  • 이준성;한영희;한상철;성태현;김상준
    • 한국초전도ㆍ저온공학회논문지
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    • 제3권1호
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    • pp.22-28
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    • 2001
  • A vortical axis flywheel system was conceptualized, which uses a hybrid superconductor bearing set to carry the wheel part load. The multiple designs of magnetic bearing and superconductor bearing were analyzed by using conventional numerical magnetostatic analysis method The best medels were selected among four different types of Permanent magnet bearings for upper bearing and two types of superconductor bearing for lower bearing, respectively These results were discussed in regard of application to the flywheel system with a Passive hybrid magnetic bearing set.

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