• Title/Summary/Keyword: Bearing characteristics

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Analysis and Experimental Investigation of Cylindrical Hydrostatic Bearing (진원형 정수압 베어링의 해석 및 실험적 고찰)

  • 문호지;한동철
    • Tribology and Lubricants
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    • v.6 no.1
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    • pp.57-67
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    • 1990
  • For increasing the performance of Machine tools, the improvement of the static and dynamic characteristics of spindle bearing is important. In this paper are the static characteristics, the pressure distribution, friction force and outlet flow rate, and the dynamic characteristics stiffness and damping coefficient, of a cylindrical hydrostatic journal bearing with multi oil pockets are analyzed.

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

  • 정광섭;김병주;송무석;이영제
    • Tribology and Lubricants
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    • v.13 no.3
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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.

A Calculation of Superconductor Bearing Characteristics (초전도 베어링 특성 계산)

  • 윤희중;한영희;한상철;정년호;김경진;박병삼;오제명;성태현
    • Progress in Superconductivity
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    • v.5 no.2
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    • pp.141-143
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    • 2004
  • For designing a flywheel system using superconductor, it is necessary to understand the basic characteristics of the classical superconductor bearing. It is difficult to expect the characteristics of superconductor bearings using models that have been introduced up to now. In the "Frozen image" concept, the farce between the permanent magnet and the superconductor can be divided into two forces between permanent magnet and two imaginary magnets in the superconductor; one represents attraction farce and the other represents a repulsion force. We calculated the characteristics of two superconductor bearings, such as an axial, the radial stiffness and the levitation force. This calculation method was very helpful to expect the characteristics of the superconductor bearings. Using this model, we established the optimum condition for the superconductor bearing.r bearing.

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Effect on the Compliance of Spindle -Bearing System by the Assembling Tolerance (축-베어링계의 컴플라이언스 특성에 미치는 조립공차의 영향)

  • 이강재;서장력;이선규
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.10a
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    • pp.995-999
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    • 1995
  • In spindle-bearing system, the displacement characteristics of the bearing by the load applied on the spindle are affected greatly by the assembling tolerance between the spindle and housing assembled to support the bearing. Also in spindle system of rotational operation, the compliance characteristic of the bearing is expected to be varied frequently by the thermal deformation of the spindle and the housing. To predict the thermal deformation of the spindle including heat generation of the bearing, we need to examine the effect on the compliance of spindle-bearing system by the assembling tolerance. In this paper, we proposed the load-displacement relation expression considering the effect which the variation of contact pressure due to the radial directional assembling tolerance between the bearing and the housing influences on the axial and radial directional displacement characteristics of the bearing. Furthermore, for several assembling systems of bearings and housings having all different assembling tolerances, we proposed a method to predict exactly the variation of the bearing preload which is sensitive to the thermal deformation by showing the propriety with experimental results.

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상부패드의 형상변경을 통한 증기터빈용 Anti-spragging 틸팅패드 저널베어링 개발(2-1)

  • Na, Un-Hak
    • 열병합발전
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    • s.50
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    • pp.18-22
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    • 2006
  • The tilting pad journal bearing has widely used to support high pressure/high rotating turbine rotors owing to their inherent dynamic stability characteristics. However, fatigue damages in the upper unlcaded pads and the break of locking pins etc. by pad spragging were continuously taken place in the actual steam turbines. The purpose of this paper is to develope a new bearing model that can prevent bearing damage problem effectively by pad spragging in a tilting pad journal bearing. A new bearing model which has a wedged groove is suggested from the studies of spragging mechanism performed by previously research works. The spragging characteristics of the upper unloaded pad are studied experimentally in order to verify the reliability of a new bearing model. It can be known that the phenomenon of pad spragging nearly does not occur in the new bearing model under the various experimental conditions. And it is observed that any kinds of bearing failures by pad spragging does not detect in the application of actual steam turbines.

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The Effect of Oil-Starvation on the Lubrication Characteristics of High-Speed Bearing: Part II-Roller Bearing (가스터어빈용 고속 베어링의 Oil-Starvation 윤활특성: Part II-Roller Bearing)

  • Kim, Ki-Tae
    • Tribology and Lubricants
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    • v.13 no.1
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    • pp.76-81
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    • 1997
  • The lubrication characteristics of high-speed roller bearings at oil-starvation have been investigated empirically using the bearings employed in small industrial gas turbine engines. Testing was done by simulating the oil-starvation conditions in engines, such as stopping the oil-supply to the bearing during normal operating, starting without oil-supply at atmospheric temperature, and accelerating with oil-supply at atmospheric temperature. During testing, the temperature of bearing, the power consumption, and the rotating resistance of the bearing were measured. From this study, on the contrary to the ball bearing, it was found that the resistance of the bearing was higher at the regime of without oil-supply than that at the regime of with oil-supply, despite less power consumption.

Efffects of Synchronous Vibration of Bearing on Stability of Externally Pressurized Air Journal Bearing (베어링의 동기 진동이 외부 가압 공기 저어널 베어링의 안정성에 미치는 영향)

  • Lee, Jeong-Bae;Kim, Kyung-Woong
    • Tribology and Lubricants
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    • v.13 no.1
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    • pp.28-33
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    • 1997
  • Results of theoretical investigations of the stability characteristics of externally pressurized air journal bearing, of which bearing is synchronously vibrate with respect to rotor, are presented. Linearized perturbation method is used to get the dynamic coefficients of air bearing, and the Routh-Hurwitz criterion is used to obtain stability map. The stability characteristics operating at zero steady-state eccentricity is investigated of various phase difference of bearing to rotor. It is shown that stability of air bearing is greatly influenced by synchronous motion of bearing, there exists optimum phase difference which gives maximum stability threshold.

A Study on the Active Control of Air Bearing (공기베어링의 능동제어에 관한 연구)

  • Lee, Jeong-Bae;Kim, Kyung-Woong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.8
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    • pp.2501-2507
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    • 1996
  • In this paper actively controlled air bearing is investigated to overcome the defects of air bearing such as low stiffness and damping coefficients. The actively controlled air beairng is composed of an air bearing, a gap sensor, a controller, and a piezo actuator. By controlling the position of air bearing with piezo actuator, the position of floating object is controlled. In this study the proportional-Integral-Derivative controller is employed. Active air bearing is investigated numerically and experimentally. There is good agreement between the simulation and the experimental results. It is shown that the stiffness and damping characteristics and positioning experimental results. It is shown that the stiffness and damping characteristics and positioning accuracy of air bearing can be improved by means of adopting actively controlled air bearing.

Analysis of a Bydrodynamic Bearing of a BDD Spindle Motor Due to Elevated Temperature (온도변화에 의한 HDD 유체 동압 베어링의 특성 해석)

  • Kim Kwan Soo;Kim Hak Woon;Lee Haeng Soo;Kim Chul Soon;Jang Gun Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.5 s.236
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    • pp.762-769
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    • 2005
  • This paper presents a method to investigate the characteristics of a hydrodynamic bearing of a HDD spindle motor due to elevated temperature considering the variation of the clearance as well as the lubricant viscosity. Iterative finite element analysis of the heat conduction and the thermal deformation is performed to determine the viscosity and clearance of a hydrodynamic bearing due to elevated temperature until the temperature of the bearing area converges. Proposed method is verified by comparing the calculated temperature with the measured one in elevated surrounding temperature as well as in room temperature. This research shows that elevated temperature changes the clearance as well as the lubricant viscosity of the hydrodynamic bearing of a HDD spindle motor. Once the viscosity and the clearance of a hydrodynamic bearing of a HDD spindle motor are determined, finite element analysis of the Reynolds equation is performed to investigate the static and dynamic characteristics of a hydrodynamic bearing of a HDB spindle motor due to elevated temperature. It also shows that the variation of clearance due to elevated temperature is another important design consideration to affect the static and dynamic characteristics of a hydrodynamic bearing of a HDD spindle motor

Analysis of a Hydrodynamic Bearing of a HDD Spindle Motor Due to Elevated Temperature (온도변화에 의한 HDD 유체 동압 베어링의 특성 해석)

  • 김학운;김관수;장건희;이행수;김철순
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.556-563
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    • 2003
  • This paper presents a method to investigate the characteristics of a hydrodynamic bearing of a HDD spindle motor due to elevated temperature considering the variation of the clearance as well as the lubricant viscosity. Iterative finite element analysis of the heat conduction and the thermal deformation is performed to determine the viscosity and clearance of a hydrodynamic bearing due to elevated temperature until the temperature of the bearing area converges. Proposed method is verified by comparing the calculated temperature with the measured one in elevated surrounding temperature as well as in room temperature. This research shows that elevated temperature changes the clearance as well as the lubricant viscosity of the hydrodynamic bearing of a HDD spindle motor. Once the viscosity and clearance of a hydrodynamic bearing of a HDD spindle motor are determined, finite element analysis of the Reynolds equation is performed to investigate the static and dynamic characteristics of a hydrodynamic bearing of a HDD spindle motor due to elevated temperature. It also shows that the variation of clearance due to elevated temperature is another important design consideration to affect the static and dynamic characteristics of a hydrodynamic bearing of a HDD spindle motor.

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