• Title/Summary/Keyword: Oil-air Lubrication

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Structural Characteristics Analysis of a High-Speed Horizontal Machining Center with Built-in Motor and Linear Motors (냉장형 모터와 리니어 모터를 적용한 초고속 수평형 머시닝센터의 구조 특성 해석)

  • 김석일;조재완
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2004.10a
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    • pp.326-333
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    • 2004
  • This paper presents the structural characteristics analysis of a high-speed horizontal machining center with spindle speed of 50, 000rpm and feedrate of 120m/min. The spindle system is designed based on the built-in motor, angular contact ceramic ball bearings, oil-air lubrication and oil-jacket cooling method. The X-axis and Y-axis feeding systems are composed of the linear motor and linear motion guides, and the Z-axis feeding system is composed of the servo-motor, ball screw and linear motion guide. The structural analysis model of the high-speed horizontal machining center is constructed by the finite element method, and the validity of structural design is estimated based on the structural deformation of the high-speed horizontal machining center and spindle nose caused by the gravity and inertia forces.

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초정밀 앵귤러 컨택트 볼 베어링 개발

  • 현준수;문호근;박태조
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1998.04a
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    • pp.300-306
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    • 1998
  • A high precision angular contact ball bearing is developed by Hanwha Machinery Co. The developed bearing is 7004C with P4 class. The performance test was succeful until 60,000 rpm.

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이중냉각자켓의 냉각유량에 따른 모터내장형 고속주축계의 열특성

  • 최대봉;황주호;임경진
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.239-243
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    • 1997
  • The heat generation is the most important problem in the motor integrated spindle. Double cooling jacket in necessary to reduce the thermal displacement and to get the stable temperature disribution for the housing. In this study, the effects of temperature distribution and thermal displacement for the spindle system according to the variation of cooling oil flow rate are investigated experimentally on the motor-integrated spindle with double cooling jacket system. The experimental spindel system is composed with the angular contact steel ball bearings, oil-air lubrication, air or oil jacket cooling system.

Evaluation of Machinability of Micro groove by Cutting Environments in High Speed Machining using Ball End Mill (소구경 미세홈 고속가공시 가공환경변화에 따른 가공성 평가)

  • 정연행;이태문;강명창;이득우;김정석
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2002.04a
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    • pp.32-37
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    • 2002
  • High speed machining is one of most effective technologies to improve productivity. It can give great advantage for manufacture of die and Moulds. However, when the high speed machining of materials, especially in machining of micro groove, a severely thermal demage was generated on workpiece and tool. Generally, the cutting fluid is used to improve penetration, lubrication, and cooling effect. In order to rise the performance of lubrication, it contains extreme pressure agents (Cl, S, P). But the environment of work room go bad by those additive Therefore, the compressed chilly air with Oil mist system was developed to replace the conventional cutting fluid system. This paper carried out the tests to evaluate the machinability by the cutting environment in high speed micro groove machining of NAK80 (HRC40). Compressed chilly air with oil mist was ejected on the contact area between cutting edge and workpiece. The effectiveness of this developed compressed chilly air with oil mist system was evaluated in terms of tool life. The results showed that the tool life of carbide tool coated TiAIN with compressed chilly air mist cooling was much longer than with dry and flood coolant when cutting the material.

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Cutting Characteristics of Micro grooving by Cutting Environments in High Speed Machining using Ball End Mill (미세홈 고속가공시 절삭유제 공급방식에 따른 가공성 평가)

  • 배정철;정연행;강명창;이득우;김정석
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.10a
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    • pp.172-175
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    • 2002
  • High speed machining is one of the most effective technologies to improve productivity. It can give great advantage for manufacture of die and Moulds. However, when machining of micro groove in high speed machining a severely thermal damage was generated on workpiece and cutting tool. Generally, the cutting fluid is used to improve penetration. lubrication. and cooling effect. In order to rise the performance of lubrication. it contains extreme pressure agents (Cl, S, P). But the environment of work room go bad by those additive. Therefore, the compressed chilly air with oil mist system was developed to replace the conventional cutting fluid system. This paper carried out the tests to evaluate the machinability by the cutting environment in high speed micro groove machining of NAK80 (HrC40). Compressed chilly air with oil mist was ejected on the contact area between cutting edge and workpiece. The effect of this developed compressed chilly air with oil mist system was evaluated in terms of tool life. The results showed that the tool lift of carbide tool coated TiAlN with compressed chilly air mist cooling was much longer than that of the dry and flood coolant when cutting the material.

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Experimental investigation of frictional resistance reduction with air layer on the hull bottom of a ship

  • Jang, Jinho;Choi, Soon Ho;Ahn, Sung-Mok;Kim, Booki;Seo, Jong Soo
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.6 no.2
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    • pp.363-379
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    • 2014
  • In an effort to cope with recent high oil price and global warming, developments of air lubricated ships have been pursued to reduce greenhouse gas emissions and to save fuel costs by reducing the frictional resistance. In this study, reduction in the frictional resistance by air lubrication with air layers generated on the lower surface of a flat plate was investigated experimentally in the large water tunnel of SSMB. The generated air layers were observed, and changes in the local frictional drag were measured at various flow rates of injected air. The results indicated that air lubrication with air layers might be useful in reducing the frictional resistance at specific conditions of air injection. Accordingly, resistance and self-propulsion tests for a 66K DWT bulk carrier were carried out in the towing tank of SSMB to estimate the expected net power savings.

Parametric Study on the Design of Turbocharger Journal Bearing - Aeration Effects

  • Chun, Sang-Myung
    • KSTLE International Journal
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    • v.7 no.2
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    • pp.35-44
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    • 2006
  • Turbocharger bearings are under the circumstance of high temperature, moreover rotated at high speed. It is necessary to be designed overcoming the high temperature. So the type of oil inlet port, the inlet oil temperature and the sort of engine oil should be designed, controlled and selected carefully in order to reduce the bearing inside temperature. In this study, the influence of aerated oil on a high-speed journal bearing is also examined by using the classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of air-oil mixture in fluid-film bearing. Convection to the walls and mixing with supply oil and re-circulating oil are considered. The considered parameters for the study of bubbly lubrication are oil inlet port's type, oil aeration level and shaft speed. It is found that the type of oil inlet ports and shaft speed play important roles in determining the temperature and pressure, then the friction and load of journal bearing at high speed operation. Also, the results show that, under extremely high shaft speed, the high shear effects on aerated oil and the high temperature effects are canceled out each other. So, the bearing load and friction show almost no difference between the aerated oil and pure oil.

Aeration Effects on the Performance of Turbocharger Journal Bearing under Constant Load Operating Condition (일정하중 운전조건 하에서 공기혼입이 터보챠져 저어널베이링의 성능에 미치는 영향)

  • Chun, Sang-Myung
    • Tribology and Lubricants
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    • v.23 no.5
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    • pp.207-218
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    • 2007
  • Turbocharger bearings are under the circumstance of high temperature, moreover rotated at high speed. It is necessary to be designed overcoming the high temperature. So the type of oil inlet port, the inlet oil temperature and the sort of engine oil should be designed, controlled and selected carefully in order to reduce the bearing inside temperature. In this study, the influence of aerated oil on a high-speed journal bearing is also examined by using the classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of air-oil mixture in fluid-film bearing. Convection to the walls and mixing with supply oil and re-circulating oil are considered. The considered parameters for the study of bubbly lubrication are oil inlet port's type, oil aeration level and shaft speed. It is found that the type of oil inlet ports and shaft speed play important roles in determining the temperature and pressure distribution, then the friction in a journal bearing at high speed operation. Also, the results show that, under extremely high shaft speed, the high shear effects on aerated oil and the high temperature effects are canceled out each other. So, the bearing load and friction show almost no difference between the aerated oil and pure oil.

The Effect of Eccentricity on Aerated Oil in High-Speed Journal Bearing

  • Chun, Sang Myung
    • KSTLE International Journal
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    • v.2 no.1
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    • pp.1-11
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    • 2001
  • The influence of aerated oil on a high-speed journal bearing is examined by classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of air-oil mixture in fluid-film bearing. Convection to the walls and mixing with supply oil and re-circulating oil are considered. With changing eccentricity ratio, it is investigated the effects of air bubbles on the performance of a high-speed plain journal bearing. Just at the moderate eccentricity ratios, even if the involved aeration levels are not so severe and the entrained air bubble sizes are not so small, it is found that the bearing load and friction force may be changed so visibly for the high speed bearing operation.

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Evaluation of Oxidation Stability for Diesel Engine Oil by Hot-Tube Oxidation Test (Hot-Tube Oxidation Test에 의한 디젤엔진오일의 산화안정성 평가)

  • 정근우;조원오;김영운;서인옥;임수진
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1998.10a
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    • pp.175-180
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    • 1998
  • This paper describes evaluation of oxidation stability for diesel engine oils by Hot-tube oxidation tester at high temperature. Evaluation was rated by visual inspection of lacquer in capillary glass tube and TAN determination of used oil. Air, NO$_2$-air and SO$_2$-air mixed gases were used as oxidizing gas. One oil which has low oxidation stability is selected and reformulated by addition of some additives such as antioxidant, detergent and disperant to improve oxidation stability. As a results of reformulation, antioxidant and detergent was effective for improvement of high temperture oxidation stability on diesel engine oil.

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