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고속 가공기를 활용한 비구면 안경렌즈 유리금형용 세라믹코어 가공기술
류근만(Geun-Man Ryu),김효식(Hyo-Sik Kim),김홍택(Hong-Tek Kim),양순철(Sun-Choel Yang),장기수(Ki-Soo Jang),김동익(Dong-Ik Kim),원종호(Jong-Ho Won),김건희(Geon-Hee Kim) 한국기계가공학회 2012 한국기계가공학회지 Vol.11 No.3
Ceramic core processing technology using 5-axis high-speed cutting machine is applied to make the glass molds for aspherical ophthalmic lenses. In the technology, optimum processing conditions for aspherical ceramic molds are based on minimal experimental data of surface roughness. Such surface roughness is influenced by fabricating tools, cutting speed, feed rate, and depth of cut, respectively. In this paper, we present that surface roughness and shape accuracy of aspheric ceramic mold obtained by optimum processing conditions are Pa 0.6184㎛ and Pt 5.0301㎛ , respectively, and propose that these values are sufficiently possible to apply to making the glass molds for aspherical ophthalmic lenses.
포세린 소성시 냉각속도가 3 mol% 이트리아 안정화 지르코니아의 광학적 특성에 미치는 영향
신혜정,권용훈,설효정 대한치과재료학회 2021 대한치과재료학회지 Vol.48 No.4
This study investigated the effect of the difference in the cooling rates on the optical properties of zirconia during the simulated firing of porcelain, without a porcelain layer on a zirconia core ceramic. No difference was observed in the average transmittance of zirconia with the cooling rate during simulated firing (p>0.05). In all groups, the average transmittance decreased from approximately 44% to approximately 28% (p<0.001) as the thickness increased from 0.51 mm to 2.0 mm. No difference was observed in the translucency and opalescence parameters of zirconia with the cooling rate during the simulated firing of porcelain (p>0.05). In all groups, the translucency decreased from approximately 16 to approximately 5 (p<0.001), while the opalescence increased from approximately 6 to approximately 11 (p<0.001) as the thickness increased from 0.51 mm to 2.00 mm. Thus, the average transmittance and translucency parameter decreased exponentially as the thickness increased in all groups regardless of the cooling rate during simulated porcelain firing, while the opalescence parameter increased in a parabolic manner. Therefore, in this study, even if porcelain is fired at a cooling rate higher or lower than the typical cooling rate when manufacturing a prosthesis with a zirconia core, the optical properties of zirconia are not expected to be significantly affected. 본 연구에서는 지르코니아 코어 세라믹에 포세린을 축성하지 않고 모의 소성 시 냉각 속도의 차이가 지르코니아의 광학적 특성에 미치는 영향을 알아보았다. 그 결과 포세린 모의소성시 냉각속도에 따른 지르코니아의 평균 투과율의 유의차는 나타나지 않았다(p>0.05). 모든 군에서 시편 두께가 0.51 mm에서 2.0 mm로 증가할수록 평균 투과율은 약 44%에서 약 28%로 감소하였다(p<0.001). 포세린 모의소성시 냉각속도에 따른 지르코니아의 반투명도 매개변수의 차이는 없었다(p>0.05). 모든 군에서 시편 두께가 0.51 mm에서 2.0 mm로 증가할수록 반투명 매개변수는 약 16에서 약 5로 감소하였다(p<0.001). 포세린 모의소성시 냉각속도에 따른 지르코니아의 유백광도 매개변수의 차이는 없었다 (p>0.05). 모든 군에서 시편 두께가 0.51 mm에서 2.0 mm로 증가할수록 유백광도 매개변수는 약 6에서 약 11로 증가하였다(p<0.001). 이상으로부터 포세린 모의소성시 냉각속도에 상관없이 모든 시험군에서 두께가 증가할수록 평균 투과율과 반투명도 매개변수는 지수함수적으로 감소하였으며 유백광도 매개변수는 포물선적으로 증가하였다. 따라서 본 연구의 한계내에서 지르코니아 코어를 사용한 보철물의 제작시 제조사에 의해 제공되는 일반적인 냉각속도보다 높거나 낮은 냉각속도로 포세린을 소성하더라도 지르코니아의 광학적특성에는 큰 영향을 주지 않을 것으로 생각된다.
다이아몬드 공구에 의한 세라믹스의 가공 메카니즘에 관한 연구
김광민(Kwang-Min Kim),최성대(Seong-Dae Choi),홍영배(Young-Bae Hong) 한국생산제조학회 2011 한국생산제조시스템학회 학술발표대회 논문집 Vol.2011 No.4
In this study, the wear of diamond tools carried out drilling of sintered alumina ceramics. Thickness were observed by video microscopy equipment multimedia tool wear generated during drilling. Effect of tool wear and tool rotation speed is the speed with increasing speed and processing tools, tool wear rate decreased. The quality of the roundness of the hole, it was getting worse with increasing tool rotation speed, according to the increase in processing speed, the standard deviation of roundness of the hole better.
김광민(Kwang-Min Kim),최성대(Seong-Dae Choi),홍영배(Young-Bae Hong) 한국기계가공학회 2011 한국기계가공학회지 Vol.10 No.2
In this study, the variation of the cutting forces generated in the machining process were evaluated experimentally. A material of Al₂O₃ ceramic and a tool of the dynamometer were used for the measurements of the cutting forces. With the constant rates of the feed and the tool rotation, the cutting forces were measured along three axial directions(X, Y, Z axis) for the various values of the hollow ratio. It was found that the cutting force be increasing linearly along the direction of Z axis, but along X, Y axis be not varied. Also from the viewpoint of the precesses of the hole drilling, the cutting force was found to be increasing sharply at the beginning process, but from the eighth process be increasing smoothly. As conclusions, the cutting force generated by machining for the material of Al₂O₃ ceramic are influenced more significantly by the feed rate and the hollow ratio than by the tool rotational speed.
박상희(Sang-Hee Park),김광민(Kwang-Min Kim),최성대(Seong-Dae Choi),홍영배(Young-Bae Hong) 한국기계가공학회 2011 한국기계가공학회지 Vol.10 No.1
In this study, coring with diamond core drill on the sintered Al₂O₃ ceramic plate were carried out with different coring conditions such as various cutting speed and feed rate to evaluate their effectiveness on the wearing behavior of diamond tool and coring quality. The wearing rate of diamond core drill were getting better with increasing cutting speed and feed rate but the quality of cored hole were getting worse as increasing cutting speed and feed rate.