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휨 변형 최소화 근접 냉각 금형을 통한 고성능 고효율 플라스틱 축류팬 개발
신광호,김미애,채보혜,박상욱,김용대 한국금형공학회 2019 한국금형공학회지 Vol.13 No.1
The cooling unit of the industrial showcase consists of a compressor, a condenser and an evaporator. An axial fan is used to circulate the air to improve the efficiency of the heat exchanger. In the past, aluminum fans have been used, which have problems such as low performance, efficiency, high failure rate, and high noise. This study is to develop high performance, high efficiency plastic fan replacing aluminum fan. A major factor in determining the performance and noise of an axial fan is the angle and cross-sectional shape of the blade, which is suitable for raising the lift force, thereby controlling the vortex, which is the main cause of noise and performance degradation. In order to produce a high efficiency injection molded fan, it is necessary to develop a mold that minimizes the deformation of the injection process for the designed shape. In this study, we developed a high efficiency, low noise plastic injection fan with more than 11% performance improvement and noise reduction compared to conventional aluminum fan
폴리머코어 게이트 크기 변화가 두께 방향 수축률에 미치는 영향에 대한 연구
최한솔,정의철,박준수,김미애,채보혜,김상윤,김용대,윤경환,이성희,Choi, Han-Sol,Jeong, Eui-Chul,Park, Jun-Soo,Kim, Mi-Ae,Chae, Bo-Hye,Kim, Sang-Yun,Kim, Yong-Dae,Yoon, Kyung-Hwan,Lee, Sung-Hee 한국금형공학회 2020 한국금형공학회지 Vol.14 No.1
In this study, the variation of the shrinkage in the thickness direction of the molded parts according to the gate size of the polymer core fabricated through the 3D printer using the SLS method was studied. The polymer cores are laser sintered and the powder material is nylon base PA2200. The polymer cores have lower heat transfer rate and rigidity than the metal core due to the characteristics of the material. Therefore, the injection molding test conditions are set to minimize the deformation of the core during the injection process. The resin used in the injection molding test is a PP material. The packing condition was set to 80, 90 and 100% of the maximum injection pressure for each gate size. The runner diameter used was ∅3mm, and the gates were fabricated in semicircle shapes with cross sections 1, 2, and 3 ㎟, respectively. Thickness measurement was performed for 10 points at 2.5 mm intervals from the point 2.5 mm away from the gate, and the shrinkage to thickness was measured for each point. The shrinkage rate according to the gate size tends to decrease as the cross-sectional area decreases as the maximum injection pressure increases. The average thickness shrinkage rate was close to 0% when the packing pressure was 90% for the gate area of 1mm2. When the holding pressure was set to 100%, the shrinkage was found to decrease by 3% from the standard dimension due to the over-packing phenomenon. Therefore, the smaller the gate, the more closely the molded dimensions can be molded due to the high pressure generation. It was confirmed that precise packing process control is necessary because over-packing phenomenon may occur.
사출금형코어 및 성형수지 변화에 따른 두께 방향 수축률에 관한 연구
신성현,정의철,김미애,채보혜,손정언,김상윤,윤경환,이성희 한국금형공학회 2019 한국금형공학회지 Vol.13 No.2
In this study, selective laser sintered 3D printing mold core and metal core were used to investigate the difference of the thickness shrinkage from the gate of the injection molded part at a constant interval. SLS 3D printing mold core was made of nylon-based PA2200 powder and the metal core was manufactured by conventional machining method. As the PA2200 powder material has low strength, thermal conductivity and high specific heat characteristics compared with metal, molding conditions were set with the consideration of molten temperature and injection pressure. Crystalline resin(PP) and amorphous resin(PS) with low melting temperature and viscosity were selected for the injection molding experiment. Cooling time for processing condition was selected by checking the temperature change of the cores with a cavity temperature sensor. The cooling time of the 3D printing core was required a longer time than that of the metal core. The thickness shrinkage of the molded part compared to the core depth was measured from the gate by a constant interval. It was shown that the thickness shrinkage of the 3D printing core was 2.02~4.34% larger than that of metal core. In additions, in the case of metal core, thickness shrinkage was increased with distance from the gate, on the contrary, in the case of polymer core showed reversed aspect.
스마트폰용 Mg판재 온간 드로잉 외장 케이스에서 금형 열변형과 판재 스프링백이 제품 치수 정밀도에 미치는 영향
김흥규,송민재,정대근,채보혜,임태홍,엄요섭 한국표면공학회 2010 한국표면공학회 학술발표회 초록집 Vol.2010 No.5
온간 프레스 금형을 사용하여 마그네슘 합금 AZ31판재 재질의 스마트폰 외장 케이스를 드로잉 성형하였다. 외장케이스 제품도에 따라 가공된 금형 성형 제품의 치수는 제품도 설계 치수와 차이가 발생하였다. 치수 오차의 원인을 분석하기 위해 150℃와 250℃의 온도 조건에서 금형 가열로 인한 금형 치수 변화와 각 온도 조건에서 성형후 판재의 스프링백을 고려하였다. 유한요소해석에 의해 예측된 치수와 실제 성형 제품의 측정된 치수의 비교를 통해 열변형과 스프링백이 제품 치수 변화에 미치는 영향에 대해 고찰하였다.
자동차 시트 리클라이너 기어의 파인 블랭킹 성형에서 다이 챔퍼 형상에 따른 다이 롤 높이의 변화에 관한 연구
김종덕(Jong Deok Kim),김흥규(Heung Kyu Kim),장성호(Sung Ho Chang),채보혜(Bo Hye Chae),김미애(Mi Ae Kim) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
In this paper, the relation between die roll height and die chamfer shape was studied by fine blanking experiments for special gear. The three die inserts with different shapes of die chamfer were machined, and fine blanking tool was manufactured. Using the fine blanking tool, three experiments were conducted on the 650 ton fine blanking press. Each die roll height was measured, analyzed and we found the tendency of die roll heights on special gear to increase with increasing die chamfer angle, when the horizontal distance of die chamfer was constant. This result can be used to minimize the die roll height of fine blanking automobile parts when designing die chamfer.