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토사지반 EPB TBM의 굴진성능 및 커팅툴 마모량에 관한 실험장비 개발 및 기초연구
김대영,강한별,신영진,정재훈,이재원,Kim, Dae-Young,Kang, Han-Byul,Shin, Young Jin,Jung, Jae-Hoon,Lee, Jae-won 한국터널지하공간학회 2018 한국터널지하공간학회논문집 Vol.20 No.2
The excavation performance and the cutting tool wear prediction of shield TBM are very important issues for design and construction in TBM tunneling. For hard-rock TBMs, CSM and NTNU model have been widely used for prediction of disc cutter wear and penetration rate. But in case of soft-ground TBMs, the wear evaluation and the excavation performance have not been studied in details due to the complexity of the ground behavior and therefore few testing methods have been proposed. In this study, a new soil abrasion and penetration tester (SAPT) that simulates EPB TBM excavation process is introduced which overcomes the drawbacks of the previously developed soil abrasivity testers. Parametric tests for penetration rate, foam mixing ratio, foam concentration were conducted to evaluate influential parameters affecting TBM excavation and also ripper wear was measured in laboratory. The results of artificial soil specimen composed of 70% illite and 30% silica sand showed TBM additives such as foam play a key role in terms of excavation and tool wear. 쉴드 TBM 공사에서 굴진율 예측과 마모량 예측은 설계 및 시공 단계에서 공사비와 공기를 추정하는데 매우 중요한 요소이다. 암반지반용 TBM의 경우 실험이나 축적된 현장 data를 기반으로 CSM 모델, NTNU 모델 등이 커터 마모량부터 굴진율 예측까지 널리 사용되고 있으나, 토사지반용 TBM은 지반의 복잡성과 정확한 실험방법의 부재로 인해 이를 정확하게 예측할 수 있는 모델이 없는 실정이다. 본 연구에서는 기존에 존재하는 토사지반용 TBM 실험장치들의 단점을 개선하여 TBM 굴착과정을 모사한 실험 장치(Soil Abrasivity Penetration Test, SAPT)를 개발하였다. 회전당 관입 깊이, RPM, 첨가재(foam) 배합비 및 농도 등의 TBM 굴진에 영향을 미치는 주요 변수들에 대한 시험을 실시하여 추력, 토크 등의 변화를 살펴보고 마모량을 측정하였다. 모래(규사) 70%와 점토(일라이트) 30%로 조성된 인공시료에 대한 실험 결과 foam 배합비가 굴진성능과 마모량에 주요한 영향을 끼치는 것으로 나타났다.
구양 釜慶大學校 2002 釜慶大學校 論文集 Vol.7 No.-
In the grinding process, the degree of the sharpness in wheel grain affects the surface roughness and the dimensional accuracy. If a wheel with dull grains is used, the grinding force will be increased and the surface roughness deteriorated. To produce a precise component, the magnitude of parameters related to the wear amount of a grinding wheel has to be limited. In this study, a variation of the grinding force and the surface roughness were measured to get the machining characteristics of the WA and CBN wheels. Using the wear amount of the grinding wheel and the removal rate of workpiece, the grinding ratio was calculated. And also the wheel life was determined at a rapid decreasing point of the grinding ratio. The difference between the surface of wheel-workpiece before grinding and after wheel life was clearly verified with a microscopic photo.
김승택(Seung Taek Kim),김승목(Seung Mok Kim),박태희(Tae Hee Park),이정석(JungSeok Lee),이영제(YoungZe Lee) 한국트라이볼로지학회 2014 한국윤활학회지(윤활학회지) Vol.30 No.5
Multiple additives can help improve the performance of generally used lubricants. These additives include MoS₂, cadmium, chloride, indium, sulfide, and phosphide, which are harmful to both humans and the environment. Thus, researchers in this industry have been trying to reduce the use of these additives by finding alternatives. Nanodiamonds are one of these candidates. Nanodiamond particles are very hard, chemically stable, and highly heat-conductive. This research involved uniformly dispersing nanodiamond particles in marine engine oils via a matrix synthesis method at various concentrations (0, 0.1, 0.3, 0.5, and 1.0 wt). Friction and wear tests involved constant loads on ball-on-disk specimens, where the ball was AISI 51200 steel, the disk was AISI 1020 steel, and the sliding speed was 0.217 m/s. The lowest wear occurred at a suitable concentration of nanodiamonds (0.3 wt). However, excessive amounts of nanodiamonds caused them to act as abrasive debris because of their hardness, which increased the wear amount. The friction coefficient decreased as the nanodiamond concentration increased because their octagonal, almost spherical shape caused them to act as rolling contact elements between two surfaces.
SiC<SUB>f</SUB>/SiC 복합재의 마모 및 마찰에 의해 발생된 탄성파 특성
문창권(Chang-Kwon Moon),남기우(Ki-Woo Nam) 한국비파괴검사학회 2014 한국비파괴검사학회지 Vol.34 No.1
SiCf/SiC 복합재를 제작하여, SiCf/SiC 복합재의 섬유배향 방향에 따르는 마모 특성을 평가하고, 마모시에 발생하는 탄성파를 검출하고 분석하였다. SiCf/SiC 복합재는 섬유의 종?횡방향에 의한 마찰계수와 마모 손실은 비슷하였으나, 섬유의 수직방향은 가장 작은 값을 나타내었다. 이것은 섬유의 취성 특성 때문이라 판단되며, 마모손실과 마찰계수는 정비례의 관계를 나타내었다. SiC 단상재의 탁월주파수는 58.6 kHz를 나타내고, SiCf/SiC 복합재의 탁월주파수는 117.2와 136.7 kHz였다. The wear characteristics of SiCf/SiC composites were evaluated according to the alignment direction of the fibers, and the elastic wave-generated friction was detected and analyzed in wearing. The friction coefficient and wear loss were similar in the longitudinal and the transverse direction of the fibers. However, these values were lower in the vertical direction of the fibers because of the brittle nature of the fiber. The friction coefficient and the wear loss were directly proportional to each other. The dominant frequencies were 58.6 kHz for monolithic SiC and 117.2 and 136.7 kHz for SiCf/SiC composites, respectively.
장정환(Jeong-Hwan Jang),허철수(Zhezhu Xu),김해지(Hae-Ji Kim),김남경(Nam-Kyung Kim),류성기(Sung-Ki Lyu) 한국기계가공학회 2011 한국기계가공학회지 Vol.10 No.2
The purpose of this study is to show the friction and wear characteristics on the vapor deposited coating layers on the SCM415 steel. In this research, frictional wear characteristic of coating materials such as Ti-series, Cr-series & WC/C and TiAlN+WC/C multilayer coating was investigated under room temperature, normal air pressure and no lubricating condition. Therefore, this study carried out research on the friction coefficient, micro hardness(Hv), surface roughness and wear quantity on the vapor deposited coating layers on the SCM415 steel. As the wear experimental result, the excellence of TiAlN+WC/C multilayer coating has been proven by high micro-hardness, low friction coefficient and wear quantity.
이종형(Jong Hyung Lee),윤성훈(Sung Hun Yoon) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.8
This study investigates the characteristics of the metal powders which are used for the friction elements after mixing, compacting, and sintering. The powders with the proper size were selected to be mixed in the V-mixer for four hours, and to be compacted by 36 tons of the load. The initial density of the compacted specimen(green body) was measured, and the body was back plated by the SM20C which was electro plated by copper using the paste to give the improved bending strength. Then the back plated bodies are fully dehydrated, and were sintered in the hot press at 850℃ for two hours. Mechanical properties such as density, hardness, porous rate, coefficient of friction, and wear rate were measured for the sintered bodies to investigate the possibility of obtaining the sintered friction element with the improved characteristics.
철도차량용 금속계 소결마찰재의 조성에 따른 트라이볼로지 특성
양용준(Yong Joon Yang),이희성(Hi Sung Lee) 한국트라이볼로지학회 2014 한국윤활학회지(윤활학회지) Vol.30 No.6
Sintered metallic brake pads and low alloy heat resistance steel disks are applied to mechanical brake systems in high energy moving machines that are associated with recently developed 200km/h trains. This has led to the speed-up of conventional urban rapid transit. In this study, we use a lab-scale dynamometer to investigate the effects of the composition of friction materials on the tribological characteristics of sintered metallic brake pads and low alloy heat resistance steel under dry sliding conditions. We conduct test under a continuous pressure of 5.5 MPa at various speeds. To determine the optimal composition of friction materials for 200 km/h train, we test and the evaluate frictional characteristics such as friction coefficients, friction stability, wear rate, and the temperature of friction material, which depend on the relative composition of the Cu-Sn and Fe components. The results clearly demonstrate that the average friction coefficient is lower for all speed conditions, when a large quantity of iron power is added. The specimen of 25 wt% iron powder that was added decreased the wear of the friction materials and the roughness of the disc surface. However when 35 wt% iron powder was added, the disc roughness and the wear rate of friction materials increased By increasing the amount of iron powder, the surface roughness, and temperature of the friction materials increased, so the average friction coefficients decreased. An oxidation layer of Fe₂O₃ was formed on both friction surfaces.