• Title/Summary/Keyword: 공기정압 베어링

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A Study on the Positioning Characteristic of Aerostatic Stage (공기베어링 스테이지의 이송특성 연구)

  • 황주호;박천홍;송창규;김중천
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.668-671
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    • 2000
  • An aerostatic stage has frictionless behavior, so it has a advantage of investigation into driven mechanism such as ballscrew. In this paper, fur investigating positioning characteristic of ballscrew and feedback device in aerostatic stage, we compare the positioning characteristic between full-closed(laser scale) and semi-closed(encoder) system. Experimental results show that the aerostatic stage has a 10nm micro step response and repeatability is improved up to 1.00${\mu}{\textrm}{m}$ using laser scale. We confirm the laser scale compensate error motion of ballscrew, so acquire 1.12${\mu}{\textrm}{m}$ positioning accuracy.

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

  • 이종렬;김보언;안지훈;이득우
    • Tribology and Lubricants
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    • v.17 no.1
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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.

Development of a Static Pressure Radial Air Bearing and Estimate of Design Variables (정압형 레디얼 공기베어링 개발 및 설계인자 영향 평가)

  • Kim, Ock-Hyun;Lee, Kyu-Ho
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.21 no.3
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    • pp.502-506
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    • 2012
  • Air bearing is characterized by its extremely low friction and cleanliness such that it is widely used especially for spindles with ultra-high rotational speed at several tens of thousands rpm. This paper contributes to design of a static radial air bearing suggesting numerical analysis to anticipate its performances. The numerical analysis is an iteration method based on finite difference formulation of the Reynolds equation. A prototype air bearing has been designed and manufactured. Its load capacity has been measured and compared with the numerical solutions. The result shows good consistency between the experiment and theory, which informs that the numerical analysis can be used as an useful tool to anticipate the performances. Effects of design variables on the bearing performance have been examined by Taguchi's experimental methods using orthogonal array. Number of holes for supplying pressurized air, clearance between shaft and bearing, the hole diameter and bearing length are chosen for the design variables. The result shows that the clearance and the bearing length are the most influential variables while the others can be considered as almost negligible.

A Study of Micro Machining Using Ultra Precision Machine (초정밀 가공기 제작을 통한 미세가공에 관한 연구)

  • 김석원;김상기;정우섭;이채문;이득우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.97-100
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    • 2004
  • In recent years, a demand for micro-structure machining is increasing by the development of information and optics industries. Micro machining technology is in general well known in the field of lithograghy. However, the requirement of producing micro machine and/or micro mechanism with metal materials will be increased since a variety of workpiece configurations can be easily made. In this paper, ultra precision machine is developed to obtain micro groove and mirror surface using single crystal diamond tool. According to the cutting experiment, no burr was found at the edge of V-grooves, and the surface roughness of copper is about 1~3nm Ra. It is verified that ultra precision machine is effective to high precision machining.

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An Experimental Study on Dynamic Stiffness Measurement of Air Journal Bearing (공기 정압 저어널 베어링에서 동강성 측정에 관한 실험적 연구)

  • 이종렬;이준석;이득우;김태형;박보선
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.04a
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    • pp.429-434
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    • 2001
  • This paper has been presented the dynamic effect by the journal speed, eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing two row sources position of air bearing is different from previous investigations in the side of pressure distribution of air film by the wedge effects. An experimental study was performed to compare theoretical analysis. The dynamic stiffness was measured in actual cutting. It helps predicting of air spindle s characteristic in machining of die more precisely. The results of investigated characteristics was applied to air spindle for high speed milling.

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Influence of the environments on the movement precision of the guide table using externally pressurized porous air bearing (다공질 정압공기 베어링을 이용한 직진 테이블에 있어 주위환경이 움직임 정밀.정확도에 미치는 영향)

  • 한응교;허석환;노병옥
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.4
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    • pp.721-729
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    • 1988
  • Recently, the precision required by precision manufacturing and machinery related to electronics is within the domain of submicron that it is difficult to evaluate them by traditional measuring equipments and methods. Accordingly, precision of sub 0.1.mu.m super precise position-decision-apparatus and straight-guide air bearing have been researched and they are almost ready to be used. In utilizing straight-guide-table for super-precision-measurement which used externally pressurized porous air bearing as a way of externally pressurized air bearing, the high-precision-straight movement is the most crucial. In this study, the researcher conducted the experimental study with trial manufacture to see how the surrounding temperature and support condition influenced the selection and allocation of the machine composing element which is important to the high-precision-straight movement. The researcher finding showed that when the property of the rail part and support part of the semi-closed slider form is different, the heat generation of the working motor and surrounding temperature influence the high-precision-straight movement significantly and the researcher showed the influence of the condition of central load and eccentric load to the straight movement precision when the support stand of the straight-table was supported by numerical values.

Performance Evaluation of Compressor to Develop 500W Class Ultra-Micro Gas Turbine (500W급 초소형 가스터빈 개발을 위한 압축기 성능 평가)

  • Seo, JeongMin;Park, Jun Young;Choi, Bum Seok;Park, Moo Ryong
    • The KSFM Journal of Fluid Machinery
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    • v.15 no.6
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    • pp.51-57
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    • 2012
  • Performance evaluation of a compressor is conducted to develop 500W class ultra-micro gas turbine (UMGT) for power generation. The performance evaluation is essential to check the performance of the components of UMGT, a radial turbine, a centrifugal compressor, an angular combustor and a shaft, which have been already designed in previous researches. The purpose of this study is to introduce the development process of the performance testing equipments of the UMGT and to present the results of compressor performance test. For the performance evaluation of the compressor, two test equipments are developed and the initial test equipment uses commercial static air bearings with long shaft. In the improved test equipment, static air bearing is improved to increase rotating speed and compressed nitrogen gas is used for utility gas of the static air bearing to supply compressed air in a stable and steady way. To increase rotating speed to 320,000 rpm, 80% speed of design speed, compressed air is provided to the turbine. The performance map of the compressor with the 50%, 60%, 70%, 80% speed of design point is presented. The results of the performance test of compressor show a good agreement with the results of 3D CFD.