• Title/Summary/Keyword: 하이브리드 윤활

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Characteristics of Tool Wear and Surface Roughness using for Hybrid Lubrication in Micro-Milling Process of Flexible Fine Die (플렉서블 양각금형의 마이크로 밀링가공에서 하이브리드 윤활공정에 따른 공구마멸과 표면조도 특성)

  • Kim, Min-Wook;Ryu, Ki-Teak;Kang, Myung-Chang
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.12 no.6
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    • pp.30-36
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    • 2013
  • An FFD(flexible fine die) is an embossed mold that consists of a thin plate ranging from 0.6 to 3 mm in thickness. FFDs are primarily used for cutting LCD films and F-PCB sheets. In the high-speed micro-milling process of flexible fine dies, the lubrication and cooling of the cutting edges is very important from the aspect of eco machining and cutting performance. In this paper, a comparative study of tool wear and surface roughness between cutting fluid and hybrid lubrication for eco-machining of FFD was conducted for processes of high-speed machining of highly hardened material (STC5, HRC52). Especially, the incorporated fluid method for eco machining, in which the cutting performances can be simultaneously measured, was introduced. The machining results show that hybrid lubrication, instead of conventional cutting fluid, leads to excellent tool wear and surface roughness and represents the proper conditions for eco micro-machining of flexible fine dies.

Numerical Simulation of a Two-Stage Hybrid Heat Pump (2단 압축 하이브리드 히트펌프의 특성 시뮬레이션)

  • Jeong, Si-Young;Yun, Han-Gu;Park, Ki-Woong;Park, Seong-Ryong;Kim, Min-Sung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.2
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    • pp.191-196
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    • 2010
  • Hybrid heat pumps, which combine the vapor compression and absorption heat pump cycle, can efficiently produce hot water of $80^{\circ}-90^{\circ}C$ from the low temperature of ${\sim}50^{\circ}C$. In this study, the performance of a two-stage hybrid heat pump (HHP) was compared with a single-stage hybrid heat pump using EES (Engineering Equation Solver). For the same operating conditions, the two-stage HHP showed a slightly higher COP (Coefficient Of Performance) and more stable operating conditions than the single-stage HHP. Moreover, the maximum working fluid temperature of the two-stage HHP was found to be lower than that of the single-stage HHP by about 40 K, which makes the working conditions of the lubricating oil safer. The COPs of both systems decreased with increasing UA-values. However, the heat output of the HHP was increased at the same time.

Wear Properties of Hybrid Metal Matrix Composites (하이브리드 금속복합재료의 마모특성)

  • 부후이후이;송정일
    • Composites Research
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    • v.16 no.3
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    • pp.75-84
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    • 2003
  • The purpose of this study is to investigate the wear properties of Saffil/Al, Saffil/A12O3/Al and Saffil/SiC/Al hybrid metal matrix composites fabricated by squeeze casting method. Wear tests were done on a pin-on-disk friction and wear tester under both dry and lubricated conditions. The wear properties of the three composites were evaluated in many respects. The effects of Saffil fibers, $\textrm{Al}_2\textrm{O}_3$ particles and SiC particles on the wear behavior of the composites were investigated. Wear mechanisms were analyzed by observing the worn surfaces of the composites. The variation of coefficient of friction(COF) during the wear process was recorded by using a computer. Under dry sliding condition, Saffil/SiC/Al showed the best wear resistance under high temperature and high load, while the wear resistances of Saffil/Al and Saffi1/$\textrm{Al}_2\textrm{O}_3$/Al were very similar. Under dry sliding condition, the dominant wear mechanism was abrasive wear under mild load and room temperature, and the dominant wear mechanism changed to adhesive wear as load or temperature increased. Molten wear occurred at high temperature. Compared with the dry sliding condition, all three composites showed excellent wear resistance when lubricated by liquid paraffin. Under lubricated condition, Saffil/Al showed the best wear resistance among them, and its COF value was the smallest. The dominant wear mechanism of the composites under lubricated condition was microploughing, but microcracking also occurred to them to different extents.

Syntheses and Properties of Cr-Al-Mo-N Coatings Fabricated by Using a Hybrid Coating System (하이브리드 코팅 시스템을 이용한 Cr-Al-Mo-N 코팅의 합성과 기계적 특성)

  • Choe, Ji-Hwan;Kim, Gwang-Ho
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2009.05a
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    • pp.205-207
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    • 2009
  • 아크이온플래이팅 기술과 스퍼터링 기술이 결합된 하이브리드 코팅 시스템을 이용하여 STS 304와 Si 기판에 4성분계 Cr-Al-Mo-N 코팅을 증착하였다. $N_2$/Ar 혼합가스 분위기하에 아크 타겟은 Cr을 사용하였고 스퍼터링 타겟은 Al과 Mo를 사용하였으며 합성된 Cr-Al-Mo-N 코팅은 주로 치환고용된 (Cr, Al, Mo)N으로 구성되었다. 최고 경도값은 Mo 함량이 24.2 at.%일 때 35 GPa을 나타냈으며 마찰계수는 Mo의 함량이 0에서 33.2 at.%로 증가함에 따라 0.9에서 0.48로 감소하였다. 이는 $MoO_3$가 코팅면과 스틸볼 계면에서 고체 윤활제로 작용한 것으로 사료된다. 그러나 Cr-Al-Mo-N 코팅은 MoN의 낮은 내산화온도로 인하여 Cr-Al-N에 비하여 더 낮은 온도에서 산화되었다.

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SYNTHESIS AND MECHANICAL PROPERTIES OF $CrMoC_xN_{1-x}$ COATINGS DEPOSITED BY HYBRID COATING SYSTE (하이브리드 시스템을 이용한 $CrMoC_xN_{1-x}$ 박막의 제조와 기계적 물성의 변화)

  • Yun, Jun-Seo;Kim, Gwang-Ho
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2008.11a
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    • pp.81-82
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    • 2008
  • 하이브리드 코팅 시스템을 이용하여 $CrMoC_xN_{1-x}$ 박막을 AISI D2와 실리콘 웨이퍼 모재 위에 증착하였다. 박막 내 탄소 함량은 $CH_4/(CH_4+N_2)$ 가스 유량 증가에 비례하여 증가했다. 탄소 함량이 0.33일 때 44GPa의 최대강도 및 -4.4GPa의 잔류응력을 나타내었다. CrMoN 박막의 평균 마찰계수는 0.42이지만, 탄소함량을 증가함에 따라 0.31까지 감소 하였다. 이것은 박막 표면과 스틸볼 사이에서 탄소가 풍부한 층이 형성되어 일종의 고체윤활제 역할을 했기때문이다. 박막의 미세조직은 X-ray diffraction, Scanning electron microscopy, 그리고 X-ray photoelectron spectroscopy를 이용하여 분석하였다.

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Synthesis and mechanical properties of $CrAlC_xN_{1-x}$ coatings by a hybrid coating system (하이브리드 코팅 시스템을 이용한 $CrAlC_xN_{1-x}$ 코팅의 합성과 기계적 특성)

  • Choi, Ji-Hwan;Hong, Yeong-Su;Kim, Kwang-Ho
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2009.10a
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    • pp.200-200
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    • 2009
  • 아크이온플래이팅 기술과 DC 마그네트론 스퍼터링 기술이 결합된 하이브리드 코팅 시스템을 이용하여 STS 304와 Si 기판에 4성분계 CrAlCxN1-x 코팅을 증착하였다. 합성된 CrAlCxN1-x 코팅은 주로 유도결합형로 f구성되었다. CrAlCxN1-x 코팅의 carbon 함량이 0.17 at.%일 때 약 34 GPa을 나타내었으며 마찰계수는 carbon 함량이 0에서 1 at.%로 증가함에 따라 0.82에서 0.38까지 크게 감소하였다. 이는 코팅 표면과 steel 볼 사이에 amorphous carbon layer가 형성되어 고체윤활제로 작용한 것으로 사료된다.

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An Experimental Study on the Micro Friction and Wear Characteristics of Organically Modified Hybrid Ceramic Materials by A Sol-Gel Process (졸-겔 공정에 의한 유기변성 하이브리드 세라믹 물질의 미세 마찰마모 특성)

  • Han, Hung-Gu;Kong, Ho-Sung;Yoon, Eui-Sung;Yang, Seung-Ho
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.05a
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    • pp.215-225
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    • 2002
  • In order to enhance the thermal stability of binder materials of bonded type solid lubricants, several combinations of metal-alkoxide based sol-gel materials such as methyltrimethoxysilane(MTMOS), $titaniumisopropoxide(Ti(Opr^{j})_{4})$, $zirconiumisopropoxide(Zr(Opr^{j})_{4})$ and $aluminumbutoxide(Al(Obu^{t})_{4})$ were chemically modified by epoxy-, acrylic- and fluoro-silane compounds, respectively, in this work. Friction and wear characteristics of these hybrid ceramic materials were tested with a micro tribe-tester where a reciprocating steel ball slid on a test material, and the tribological property was also evaluated with respect to both heat-curing temperature and tile time. Test results generally showed that hybrid ceramic materials modified by epoxy-silane compounds had a low friction compared to others. And the higher heat-curing temperature and the longer heat treatment time resulted in the higher friction and the lower wear. IR spectroscopic analyses revealed that it was caused mainly by the increased metal oxide content in hybrid ceramics when the heat-curing temperature was over $320^{\circ}C$.

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Friction and Wear Characteristics of Bonded Film Lubricants of Organically Modified Hybrid Ceramic Binder Materials (유기변성 하이브리드 세라믹 물질을 결합제로 이용한 고체피막윤활제의 마찰마모 특성)

  • 한흥구;공호성;윤의성
    • Tribology and Lubricants
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    • v.19 no.4
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    • pp.203-210
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    • 2003
  • In order to enhance the thermal stability of binder materials of bonded type solid lubricants, several metal-alkoxide based sol-gel materials such as methyltrimethoxysilane(MTMOS), titaniumisopropoxide (Ti(Opr$\^$i/)$_4$), zirconiumisopropoxide (Zr(Opr$\^$i/)$_4$) and aluminumbutoxide (Al(Obu$\^$t/)$_4$) were modified chemically by both epoxy and acrylic silane compounds. Friction and wear characteristics of the bonded solid lubricants, whose binders were of several hybrid ceramic materials, were tested with a reciprocating tribo-tester. Wear life was evaluated with respect to the heat-curing temperature, friction temperature, type of supplement lubricants, and ratio of binder materials. Test results showed that the Si-Zr hybrid ceramic materials modified by epoxy-silane compounds had a higher wear life compared to others. Sb$_2$O$_3$ was the most effective supplement lubricants in the high temperature, and BUS analyses revealed that it was caused mainly by a strong anti-oxidation effect to MoS$_2$ particles. The higher heat-curing temperature resulted in the higher wear life, and the higher friction temperature resulted in the lower wear life.

A Numerical Analysis on the Rotordynamic Characteristics of A Hybrid Journal Bearing with Pair-Type Angled Injection Orifices (짝(Pair)형태의 경사 공급구를 갖는 하이브리드 저널 베어링의 로터 동특성에 관한 수치해석)

  • 김창호;이용복
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1997.04a
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    • pp.111-121
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    • 1997
  • The stability of a rotor-bearing system supported by swirl-controlled hybrid journal bearing with pair-type angled injection orifices is investigated for improvement of the whirl frequency ratio by allowing effective control of the tangential flow inside the bearing clearance, i.e., by achieving more freedom in controlling strength and direction of the supply tangential flow inside the bearing clearance. It is suggested that the system instability can be improved through the change of bearing dynamic characteristic parameters with the swirl control. The orifice diameter d$_0$ and recess injection angle $\alpha$ along with combinations of swirl/anti-swirl supply pressures and directions (3.0-3.0MPa, 4.0-2.0MPa, 2.0-4.0MPa) are selected for design parameters for swirl-controlled effective factors dependent on journal speeds (3000, 9000, 15000, 21000 rpm). It has been found that the orifice diameter do shows strong effects on effective maneuverability of direct-stiffness and direct damping values, while recess injection angle $\alpha$ results in substantial magnitude and direction of cross-stiffness. Specifically, recess injection parameters which are functions of angle of orifice feeding flow and recess dimensions showed very feasible effect on the stability of swirl-controlled rotor-bearing system.

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Lubricated Wear Properties of Hybrid Metal Matrix Composites (하이브리드 금속복합재료의 윤활마모특성)

  • Fu, Hui-hui;Bae, Sung-in;Ham, Kyung-chun;Song, Jung-il
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.10a
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    • pp.135-138
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    • 2002
  • The purpose of this study is to investigate the lubricated wear properties of Saffil/Al, Saffil/$Al_2O_3/Al$ and Saffil/SiC/Al hybrid metal matrix composites fabricated by squeeze casting method. Wear tests were done on a pin-on-disk friction & wear tester with long sliding distance. The wear properties of the three composites were evaluated in many respects. The effects of Saffil, $Al_2O_3$ particles and SiC particles on the wear behavior of the composites under lubricated conditions were elucidated. Wear mechanisms were analyzed by observing the worn surfaces of the composites. The variation of coefficient of friction (COF) during the wear process was recorded by using a computer. Comparing with the dry sliding condition, all three composites showed excellent wear resistance when lubricated by liquid paraffin. Under intermediate load, Saffil/Al showed best wear resistance among them, and its COF value is the smallest. The dominant wear mechanism of the composites was microploughing, but microcracking also occurred for them to different extent.

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