• Tribology and Lubricants
• /
• 제18권2호
• /
• pp.153-159
• /
• 2002

This paper describes a durability characteristics of an air-lubricated bump foil journal bearing for high speed turbomachinerys at room temperature. At first, lift-off test and load capacity test were performed to understand the general characteristics of an air-lubricated bump foil Journal bearing. A 52 N weighted bump foil bearing sleeve was lilted off from a rotating Journal at about 3,000 rpm, and produced a load capacity of 500 N at an operating speed of 15,000 rpm. The next was 500 cycles lift-off test with an air-lubricated bump foil journal bearing that had a molybdenum disulfide(MoS$_2$) solid lubricant coated top foil. Data from measuring bearing torque and temperature and the observation of rubbing surfAce were included in results. Therefore the results of this work will aid in proving durability of air-lubricated bump foil journal bearings.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 한국윤활학회 2001년도 제34회 추계학술대회 개최
• /
• pp.212-219
• /
• 2001

This paper describes a durability characteristics of an air-lubricated bump foil journal bearing for high speed turbomachinerys at room temperature. At first, lift-off test and load capacity test were performed to understand the general characteristics of an air-lubricated bump foil journal bearing. A 52N weighted bump foil bearing sleeve was lifted off from a rotating journal at about 3,000rpm, and produced a load capacity of 500N at an operating speed of 15,000rpm. The next was 500 cycles lift-off test with an air-lubricated bump foil journal bearing that had a molybdenum disulfide(MoS$_2$) solid lubricant coated top foil. Data from measuring bearing torque and temperature and the observation of rubbing surface were included in results. Therefore the results of this work will aid in proving durability of air-lubricated bump foil journal bearings.

• Tribology and Lubricants
• /
• 제17권4호
• /
• pp.290-296
• /
• 2001

Lift-off means that the rotating journal surface separates from the leaf surface in an air-lubricated multi-leaf foil journal bearing. Lift-off builds up minimum film thickness which will provide load capacity between leaves and journal. In this paper an analysis of air-lubricated multi-leaf foil journal bearing was performed with effects of multi-leaf foil deflection and compressible lubrication equation simultaneously. Minimum film thickness built up versus journal speed predicts the lift off characteristics and these results will be useful in designing and selecting the proper speed of the air-lubricated multi-leaf foil journal bearing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 한국소음진동공학회 2003년도 춘계학술대회논문집
• /
• pp.567-570
• /
• 2003

In recent years, the demand of mobile device, such as digital camera, camcorder and PDA, increases remarkably. So, requirements of the mobile information data storage used in the mobile devices increase noticeably also. 1" micro data storage is a kind of mobile storage. which has a CF type II form factor, and the similar structure of the general 3.5" HDD. In this paper, we developed the self acting air-lubricated ceramic bearing for the 1" micro data storage. The self acting air-lubricated ceramic bearing Is superior to the fluid bearing and the ball bearing on power consumption.

• KSTLE International Journal
• /
• 제2권1호
• /
• pp.46-54
• /
• 2001

The herringbone groove journal bearing (HGJB) has chevron type grooves on stationary or rotating member of the bearing so that they pump the lubricant inward the grooves when journal rotates. As a result, the pressure is generated around the journal so that the radial stiffness and dynamic stability are improved comparing to the plain journal bearing (PJB) when the bearing operates near the concentric condition. The narrow groove theory, conventionally adopted to simulate the concentric operation of HGJB, is limited to the infinite number of grooves. A numerical study of air-lubricated HGJB is presented for the finite number of grooves. The compressible isothermal Reynolds equation is solved by using Finite Element Method together with the Newton-Raphson iterative procedure and perturbation method. The solutions render the static and dynamic performances of HGJB. Comparison of present results with a PJB validates previously published finite difference solution. The HGJB's geometric parameters influence its static and dynamic characteristics. The optimum geometric parameters are presented for the air-lubricated HGJB in particular conditions.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 한국윤활학회 1999년도 제29회 춘계학술대회
• /
• pp.325-330
• /
• 1999

The dynamic behavior analysis of air-lubricated tilting pad journal bearing which considers start-up, running and shutdown Process were performed. By carrying out the experiment of shaft vibration, measurement of the vibration amplitudes supported by air lubricated tilting pad bearing and analysis of the result, we found more accurate dynamic behavior of the system. There were many investigations in these bearings, but dynamic behavior of startup, shutdown and running process were lacked. By using the experimental data we found the accurate dynamic behavior of the system.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• 제24권6호
• /
• pp.1520-1528
• /
• 2000

This study presents a method for determining bearing stiffness and damping coefficients of air-lubricated slider bearing, and shows influences of air-bearing surface geometry(recess depth, crown an d pivot location) on flying attitude and dynamic characteristics. To derive the dynamic lubrication equation, the perturbation method is applied to the generalized lubrication equation which based on linearized Boltzmann equation. The generalized lubrication equation and the dynamic lubrication equation are converted to a control volume formulation, and then, the static and dynamic pressure distributions are calculated by finite difference method. The recess depth and crown of the slider show significantly influence on flying attitude and dynamic characteristics comparing with those of pivot location.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• 제12권12호
• /
• pp.5412-5419
• /
• 2011

The need is growing for high-speed spindle because various equipment are becoming more precise, miniaturization and high speed with the development of industries. Air-lubricated dynamic bearings are widely used in the optical lithographic manufacturing of wafers to realize nearly zero friction for the motion of the stage. Air-lubricated dynamic bearing can be used in high-speed, high-precision spindle system and hard disk drive(HDD) because of its advantages such as low frictional loss, low heat generation, averaging effect leading better running accuracy. In the paper, numerical analysis is undertaken to calculate the performance of air-lubricated dynamic bearing with herringbone groove. The static performances of herringbone groove bearings which can be used to support the thrust load are calculated. Electrochemical micro machining($EC{\mu}M$) which is non-contact ultra precision machining method has been developed to fabricate the air-lubricated dynamic bearing and optimum parameters which are inter electrode gap size, concentration of electrolyte, machining time are simulated using numerical analysis program.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
• /
• pp.353-362
• /
• 2000

Herringbone groove journal bearing (HGJB) is developed to improve the static and dynamic performances of hydrodynamic journal bearing. In this study, static and dynamic compressible isothermal lubrication problems are analyzed by the finite element method together with the Newton-Raphson iterative procedure. This analysis is introduced for prediction of the static and dynamic characteristics of air lubricated HGJB for various bearing configurations. The bearing load characteristics and dynamic characteristics are dependent on geometric parameters such as asymmetric ratio, groove depth ratio, groove width ratio and groove angle.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 한국윤활학회 1998년도 제27회 춘계학술대회
• /
• pp.235-240
• /
• 1998

The inlet pressure build-up at the leading edge of bearings and its effects on the static performances are investigated theoretically. The performance analyses of air-lubricated tilting pad bearings are carried out considering the inlet pressure which is obtained by means of momentum conservation method. The results show that inlet pressure is above atmosphere pressure in front of leading edge of tilting pad bearing and there is a significant influence of the inlet pressure on the performance of bearings.