• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.336.1-336.1
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• 2014

대표적인 TCO 물질인 ITO는 디스플레이 패널이나 태양 전지 등과 같은 소자에 널리 사용되고 있다. 최근에는 대량생산 및 대면적화, 그리고 유연 디스플레이 응용을 위해 롤투롤 스퍼터링(roll to roll sputtering) 공정을 이용하여 플라스틱 기판에 ITO박막을 증착하여 ITO 필름을 제작하고 있다. 롤투롤 방식으로 ITO 필름의 제작 시 공정 변수에 따라 ITO 박막의 전기적 광학적 물성 변화가 매우 크기 때문에, 공정 변수에 따른 ITO 박막의 전기적, 광학적 특성 변화에 대한 연구의 필요성이 매우 높아지고 있다. 따라서 본 연구에서는 롤투롤 스퍼터링 방법으로 PET 기판 위에 다양한 조건으로 ITO 박막을 증착하여 공정변수에 따른 ITO 박막의 물성을 조사 하였다. 이를 위해 ITO (In/Sn=95/5 wt.%) 타겟을 사용하여 DC 파워와 산소 분압비, 열처리 온도 등을 변화시켜 낮은 면저항과 높은 광투과도를 가지는 최적의 ITO 증착 조건을 찾은 후 ITO 박막을 PET 기판 위에 두께 별로 증착 하였다. ITO 박막의 두께와 열처리 온도에 따른 전기적 특성은 면저항 측정기와 홀 측정 장치를 이용하여 분석하였고, 분광광도계와 탁도 측정기를 이용하여 광학적 특성을 관찰하였다. 또한, GIXD를 이용하여 이들 박막의 구조와 결정성에 대한 조사를 수행하였다. 이 결과들로부터 산소 분압비에 따른 ITO/PET 박막의 저항 특성 변화와 ITO 박막의 두께와 열처리 온도에 따른 구조적, 전기적, 광학적 특성을 조사하여, 롤투롤 스퍼터링법에서 공정 조건에 따른 ITO/PET 필름의 물성변화를 보고하고자 한다.

• 대한기계학회논문집A
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• 제36권4호
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• pp.429-435
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• 2012

압연공정 중에 작업롤은 스트립과의 지속적인 마찰에 의해 마모가 발생하여, 질량 불평형이 발생하게 된다. 이러한 작업롤의 질량 불평형을 고려한 압연기의 수학적 모델을 제안하였고, 이 모델은 실험에 의해 검증되었다. 작업롤은 편심을 가진 강체 로터로 가정되어, 질량 불평형의 채터 진동에 대한 영향을 분석하였다. 스핀들의 준평형 해석을 통해 계산된 조인트 힘은 압연기의 작업롤에 외력으로 작용시켰다. 압연기의 운동방정식을 직접적분법으로 풀어 과도 응답을 얻고 주파수 분석을 수행하였다. 편심은 수직 방향의 진동보다 수평 방향의 진동에 더 큰 영향을 끼쳤는데, 작업롤 반경의 1%의 편심거리도 수평 방향 채터 주파수의 진폭을 크게 상승시킬 수 있다는 것을 확인하였다.

• 소성∙가공
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• 제26권1호
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• pp.28-34
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• 2017

Multi-pass shape rolling is performed to produce long products of arbitrary cross-sectional shapes. In the past, the multi-pass shape rolling process has been designed by the trial and error method or the experience of experts based on the empirical approach. Particularly, the design of roll caliber in shape rolling is important to improve product quality and dimensional accuracy. In this paper, the caliber design and pass schedule of multi-pass shape rolling were proposed for manufacturing piston ring wire. In order to design roll caliber, major shape parameter and dimension was determined by analysis of various caliber design. FE-simulation was conducted to verify effectiveness of proposed process design. At first, forming simulation was performed to predict shape of the product. Then, fracture of the wire was evaluated by critical damage value using normalized Cockcroft-Latham criteria. The experiment was carried out and the results are within the allowable tolerance.

• 한국기계가공학회지
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• 제16권1호
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• pp.96-101
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• 2017

We have developed a compact desktop-sized nanopatterning system driven by the Roll-to-Roll (R2R) nanoimprinting (NIL) principle. The system realizes the continuous and high-speed stamping of various nanoscale patterns on a large-area flexible substrate without resorting to ponderous and complicated instruments. We first lay out the process principle based on continuous NIL on a UV-curable resin layer using a flexible nanopatterned mold. We then create conceptual and specific designs for the system by focusing on two key processes, imprinting and UV curing, which are performed in a continuous R2R fashion. We build a system with essential components and optimized modules for imprinting, UV curing, and R2R conveying to enable simple but effective nanopatterning within the desktop volume. Finally, we demonstrate several nanopatterning results such as nanolines and nanodots, which are obtained by operating the built desktop R2R NIL system on transparent and flexible substrates. Our system may be further utilized in the scalable fabrication of diverse flexible nanopatterns for many functional applications in optics, photonics, sensors, and energy harvesters.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.413-416
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• 2007

In general, by means of the electrodepositing technique, a copper foil sample was prepared with a high purity and a high density. But the mechanical properties of the electrodepositing copper foil was lower than it's the rolling copper foil. However, the production of copper foil with approximately 36 microns thick in rolling process was very difficult. This paper describes the outline of the high accuracy cold rolling in 6 high mill which was developed for the purpose of rolling very thin accurate gauge copper foil(36 micron thick), and give several rolling characteristic of 600 mm wide copper foil. a) Large strain can be accumulated pass by pass in industrial multi-pass rolling processing to overcome large critical strain for thickness accuracy through optimization of rolling schedule. b) Also, permissible tension for rolling 0.45 $\sim$ 0.036 mm thick copper strip stably in accordance with the each pass work had been established by FEM simulation results. c) During the plate rolling process, considerable values of the forces of material pressure on the tool occur. These pressures cause the elastic deformation of the roll, thus changing the shape of the deformation region. A numerical simulation of roll deflection during cold rolling is presented in the paper. d) The proposed pass schedule can roll very thin copper foil of 36 micron thickness to a tolerance of ${\pm}1$ microns. The validity of simulated results was verified into rolling experiments on the copper foil.

• 대한기계학회논문집A
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• 제35권1호
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• pp.33-37
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• 2011

디스플레이, 광학, 에너지 분야 부품의 미세형상화, 대면적화, 저가격화 요구에 대응하기 위하여 대면적 롤금형의 미세형상 가공기술개발에 대한 필요성이 대두되고 있다. 롤금형은 기존의 평판금형에 비해서 금형의 납기가 빠르고, 대면적화에 용이하며, 연속성형이 가능하다는 장점을 갖고 있다. 본 연구는 롤금형에 미세형상을 가공할 때 발생하는 형상오차의 원인을 규명하는 것을 목적으로 하고 있으며, 가공 현장에서 개선 가능한 요소로서 롤금형의 동적밸런싱 보정방안을 제시하고 있다. 기존보다 정밀한 동적밸런싱 보정을 통하여 롤금형의 질량불평형이 최대 90%까지 감소되었고, 롤금형의 진동량이 0.044 mm/sec (RMS)에서 0.004mm/sec (RMS)로 감소하였으며, 결과적으로 미세패턴의 형상정밀도가 개선되는 것을 확인할 수 있었다.

• Advances in materials Research
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• 제4권4호
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• pp.215-226
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• 2015

Experiment on roughness and micro pit defects of SUS 430 ferrite stainless steel was investigated in laboratory. The relation between roughness and glossiness with reduction in height, roll surface roughness, emulsion parameters was analyzed. The surface morphology of micro pit defects was observed by SEM, and the effects of micro pit defects on rolling reduction, roll surface roughness, emulsion parameters, lubrication oil in deformation zone and work roll diameter were discussed. With the increasing of reduction ratio strip surface roughness Ra(s), Rp(s) and Rv(s) were decreasing along rolling and width direction, the drop value in rolling direction was faster than that in width direction. The roughness and glossiness were obtained under emulsion concentration 3% and 6%, temperature $55^{\circ}C$ and $63^{\circ}C$, roll surface roughness $Ra(r)=0.5{\mu}m$, $Ra(r)=0.7{\mu}m$ and $Ra(r)=1.0{\mu}m$. The glossiness was declined rapidly when the micro defects ratio was above 23%. With the pass number increasing, the micro pit defects were reduced, uneven peak was decreased and gently along rolling direction. The micro pit defects were increased with the roll surface roughness increase. The defects ratio was declined with larger gradient at pass number 1 to 3, but gentle slope at pass number 4 to 5. When work roll diameter was small, bite angle was increasing, lubrication oil in micro pit of deformation zone was decreased, micro defects were decreased, and glossiness value on the surface of strip was increased.

• 소성∙가공
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• 제23권2호
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• pp.103-109
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• 2014

Flexibly-reconfigurable roll forming (FRRF), which is a sheet forming process for multi-curved sheet metal, may solve both the economic and technical problems incurred in using a conventional die forming process. In the FRRF process, the multi-curved sheet metal is formed by different strain distributions on the sheet metal, and the reconfigurable rollers are used as tools during the forming. Therefore, a thorough investigation focused on the reconfigurable rollers is required for the realization of the FRRF process prior to the fabrication of FRRF machine. In the current study, a series of finite element simulations were conducted to study the load distributions experienced by the reconfigurable roller. In order to verify the shape design variables, the effect of the metal thickness on the curvatures of sheet is also presented.

• 열처리공학회지
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• 제36권6호
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• pp.359-366
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• 2023

Changes in microstructure and mechanical properties of Mg-1.0Al-1.0Zn-0.2Mn-0.5Ca (AZMX1100) alloy sheet manufactured by normal casting and twin roll casting process, were studied according to process and heat treatment. Non-uniform microstructure was observed in the initial sheet produced through both processes, and in particular, tilted dendrites and shifted central segregation were observed in the twin roll casting sheet. It was homogenized through hot rolling and heat treatment, and heat treated at 350℃ and 400℃ to compare the effect of heat treatment temperature. Both sheets were homogenized by the hot rolling process, and the grain size increased as the heat treatment temperature and time increased. It was confirmed that the grain size, deviation, and distribution of the second phase were finer and more homogenized in the TRC sheet. Accordingly, mechanical properties such as hardness, formability, and tensile strength also showed better values. However, unlike other previously reported AZMX alloy systems, it showed low formability (Erichsen value), which was judged by the influence of Al2Ca present in the microstructure.

• 한국정밀공학회지
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• 제33권2호
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• pp.115-119
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• 2016

Winding is one of the major processes in roll-to-roll systems. Taper tension profile in a winding determines the distribution of stress in the radial direction, i.e., the radial stress in the wound rolls. Maximum radial stress is major cause of material defect, and this study has been actively proceeded. Traditional models of radial stress model were focused on flexible and light substrate. In this study, we developed an advanced radial stress model including effects of both these parameters(weight and stiffness) on the radial stress. The accuracy of the developed model was verified through FEM(Finite Element Method) analysis. FEM result of maximum radial stress value corresponds to 99 % in comparison to result with the model. From this study, the material defects does not occur when the steel winding. And steel industry can be applied to improve the winding process.