• Title/Summary/Keyword: 초정밀 연삭

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A Study of Optimum Molding Condition of Aspheric Glass Lens(I) ; Annealing Condition Effect (비구면 Glass렌즈 최적 성형조건 연구(I) ; 서냉조건효과)

  • Cha, Du-Hwan;Kim, Hyeon-Uk;Kim, Hye-Jeong;Kim, Jeong-Ho
    • Proceedings of the Optical Society of Korea Conference
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    • 2006.07a
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    • pp.197-198
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    • 2006
  • 본 연구에서 개발하는 성형렌즈는 그림1과 같이 한쪽 면이 비구면인 평볼록 형상이다. Glass렌즈의 고온압축성형을 위해서는 초정밀 가공기술로 제작된 성형Mold가 필요하며, Mold재질에 따른 성형기술의 확립이 필수적이다. 또한, 성형Mold의 표면과 융착반응이 없는 Glass소재가 요구된다. 본 실험을 위한 성형Mold는 코발트(Co) 함량 0.5 %의 초경합금(WC; 일본, Everloy社, 002K)을 초정밀 연삭가공하여 제작하였다. Glass소재는 전이점(Transformation Point; Tg) $572\;^{\circ}C$,항복점(Yielding Point; At) $630\;^{\circ}C$의 열적 특성을 갖는 K-BK7(일본, Sumita社)을 사용하였으며, d선에서 굴절률 및 아베수는 각각 1.51633, 64.1이다. 비구면 Glass렌즈 성형은 GMP(Glass Molding Press; 일본, Sumitomo社, Nano Press-S)장비를 사용하여 성형온도 $625\;^{\circ}C$, 서냉온도 $550\;^{\circ}C$로 고정하고 성형압력를 200-800 N 범위에서 변화시켰다. 표 1에 성형변수로 사용한 서냉속도와 서냉전환온도 조건을 나타낸다. 표1과 같이 각 서냉조건별로5장의 렌즈를 성형 후 특성값이 평균치에 가까운 3장을 선별하여 그 특성을 비교하였다. 각 조건에 따른 성형렌즈의 형상정도(일본, Panasonic社, UA3P, 자유곡면형상측정기), 두께(일본, Mitutoyo社, MDC-25M, 마이크로메터), 굴절률(일본, Shimatus社, KPR-200, 정밀굴절률측정기) 및 MTF[해상도](독일, Trioptics社, Image Master HR, MTF-Field)를 측정하여 각각의 광학적 특성을 비교 평가하였다. 비구면 Glass렌즈 성형장비와 형상측정기를 그림 2, 3에 각각 나타낸다.

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Development of diamond wheel for ultra precision and high performance grinding of difficult-to-materials (난삭재의 초정밀.고능률 연삭가공을 위한 다이아몬드숫돌의 개발)

  • Heo, Seong-Jung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.12
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    • pp.2172-2178
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    • 1997
  • Development of diamond wheel with fine grains and multi-pore structures were newely attempted. Wheels, that are employed for ultra precision and high performance grinding of difficult-to materials such as tungsten carbide alloy using tool and die materials, must have both performances to remove tool marks efficiently and to contact elastically with curved surfaces. Diamond grains were bonded firmly by a melamine resin to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures were developed to increase the flexibility of the wheel, and to induce active self-sharpening by increasing contact pressure between the wheel and work surfaces. In this paper, melamine-bonded diamond wheels are trial manufactured, then the forming method of wheels are suggested, and the grinding characteristics of wheels are also illustrated.

Development of Optimum In-process Electrolytic Dressing System in the UItraprecision Grinding (초정밀 연삭용 최적 연속 전해드레싱 시스템의 개발에 관한 연구)

  • 이은상
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1995.03a
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    • pp.82-103
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    • 1995
  • In recent years grinding techniques for precision machining of brittle materials used in electric optical and magnetic parts have been improved by using superabrasive wheel and precision grinding machine. The completion of optimum dressing of superabrasibve wheel makes possible the effective precision grinding of brittle materials. But the present dressing system cannot have control of optimum dressing of the superabrasive wheel. This study has proposed a new optimum in-process dressing of superabrasive wheel and give very effective control according to gap increase.

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A Study on the Cylindrical Grinding Technology by Electrolytic In-Process Dressing(ELID) Method (전해인프로세스드레싱법에 의한 초정밀 원통 연삭기술 연구)

  • Je, Tae-Jin;Lee, Eung-Suk
    • 연구논문집
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    • s.28
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    • pp.59-71
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    • 1998
  • The ELID(electrolytic in-process dressing) grinding method is a new precision grinding technique with the special electrolytic in-process dressing by metal bonded grinding wheel, fluid, and power supply. It is possible to make a efficient precision machining of hard and brittle materials such as ceramics, hard metals, and quenched steels by using this method, In this study, a new efficient precision grinding method with ELID was attempted for application to the machining and finishing processes of cylindrical structural components. And, we try to develop the cylindrical grinding technique for mirror surface of ceramics, tungsten carbide and SCM steel, and for the high efficiency grinding of machined parts, for example, ball screw shaft. Electrical characteristics of three different wheel grit sizes of #325, #2000 and #4000 were investigated experimentally. ELID grinding method is proved to be useful for mirror surface generation and efficient machining.

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Optical Properties of Aspheric Glass Lens using DLC Coated Molding Core (성형용 코어면 DLC 코팅에 의한 비구면 Glass렌즈 광학적 특성에 관한 연구)

  • Kim, Hyun-Uk;Cha, Du-Hwan;Lee, Dong-Gil;Kim, Sang-Suk;Kim, Hye-Jeong;Kim, Jeong-Ho;Jeong, Sang-Hwa
    • Korean Journal of Optics and Photonics
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    • v.18 no.5
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    • pp.362-366
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    • 2007
  • In this research, the optimal grinding condition has been obtained by design of experiment (DOE) fur the development of aspheric lens for the 3 Mega Pixel, 2.5x optical zoom camera-phone module. Also, the tungsten carbide (WC) mold was processed by the method of ultra precision grinding under this optimal grinding condition. The influence of diamond-liked carbon (DLC) coating on form accuracy (PV) and surface roughness (Ra) of the mold was evaluated through measurements after DCL coating using ion plating on the ground mold. Also, aspheric glass lenses were molded, some before DLC coating of the mold and some after the DLC coating. The optical characteristics of each sample, molded by the different molds, were compared with each other.

Properties of Friction Coefficient with Re-Ir Coating Surface (Re-Ir 코팅에 따른 표면 마찰 계수 특성 연구)

  • Lee, Ho-Shik;Cheon, Min-Woo;Park, Yong-Pil
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2011.05a
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    • pp.676-677
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    • 2011
  • Rhenium-Iridium(Re-Ir) thin films were deposited onto the tungsten carbide(WC) molding core by sputtering system. The Re-Ir thin films on tungsten carbide molding core were analyzed by scanning electron microscope(SEM) and surface roughness. The Re-Ir coating technique has been intensive efforts in the field of coating process because the coating technique and process have been their feature, like hardness, high elasticity, adrasion resistance and mechanical stability and also have been applied widely the industrial and biomedical areas. In this report, tungsten carbide(WC) molding core was manufactures using high performance precision machining and the efforts of Re-Ir coating on the surface roughness.

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A Study on Ultra Precision Grinding Characteristics of Tungsten Carbide $LCU\_CL$ Core (초경합금 소재 $LCU\_CL$ 코어의 초정밀 연삭 특성에 관한 연구)

  • Jeong Sanghwa;Cha Kyoungrae;Kim Hyunuk;Lee Bongju
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2005.05a
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    • pp.307-312
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    • 2005
  • As the various manufacturing technology of optical glass is developed, the aspherical lenses are applied to many fields. However, It is still very difficult to manufacture glass lens because of the high cost and the short life of core. In recent years, the demands of the aspherical glass lenses increase since it is difficult to obtain the desirable performance in the plastic lens. In the glass mold lens, it has merits of high productivity and reproductivity since lens is manufactured by the only forming with high precision mold. The fabricating conditions for glass mold lens are glass surface that does not cause fusion, viscosity of 108-1013 poise for the $0.2{\mu}m$ accuracy, and viscoelasticity for the roughness less than 100 angstrom. In this thesis, ultra-precision grinding characteristics of tungsten carbide for forming the aspherical glass lens core were studied and the result of it is applied to manufacture the tungsten carbide-base core of the glass lens used to the laser scanning unit and the camera phone.

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SEM and PV Properties of WC Core Surface with DLC Coating (초경합금(WC) 코어면의 Re-Ir 코팅에 따른 표면 조도 특성)

  • Lee, Ho-Shik;Park, Yong-Pil;Cheon, Min-Woo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2010.05a
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    • pp.828-829
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    • 2010
  • Rhenium-Iridium(Re-Ir) thin films were deposited onto the tungsten carbide(WC) molding core by sputtering system. The Re-Ir thin films on tungsten carbide molding core were analyzed by scanning electron microscope(SEM) and surface roughness. The Re-Ir coating technique has been intensive efforts in the field of coating process because the coating technique and process have been their feature, like hardness, high elasticity, adrasion resistance and mechanical stability and also have been applied widely the industrial and biomedical areas. In this report, tungsten carbide(WC) molding core was manufactures using high performance precision machining and the efforts of Re-Ir coating on the surface roughness.

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Molding and Optical Evaluation of Aspheric Glass Lenses for Camera Phone Module (카메라폰 모듈용 비구면 Glass렌즈의 성형 및 광학특성 평가)

  • Kim, Hye-Jeong;Cha, Du-Hwan;Kim, Jeong-Ho
    • Journal of Korea Society of Industrial Information Systems
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    • v.12 no.3
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    • pp.124-131
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    • 2007
  • Aspheric glass lenses was fabricated by glass molding press(GMP), which is a plano-aspheric convox shape and intended for use as an optical design of 3 megapixel and 2.5 magnifications zoom in a camera phone module. Transcription ratio of form accuracy (PV) as well as resolution properties was measured for evaluation the molded lens. Form accuracy (PV) of the mold surface was $0.127\;{\mu}m$ in an aspheric and $0.168\;{\mu}m$ in a plano, in case of the molded lens it shows $0.205\;{\mu}m$ and $0.223\;{\mu}m$, respectively. Resolution of the molded lens was measured as a MTF[Contrast]. The molded lens shows contrast of 32.9% at 80 1p/mm and the value is similar with contrast of 33% obtained simulation.

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