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다수 캐비티에서의 균형 충전을 위한 새로운 러너 시스템
장민규,박태원,정영득,Jang, Min-Kyu,Park, Tae-Won,Jeong, Yeong-Deug 한국금형공학회 2013 한국금형공학회지 Vol.7 No.1
Almost all injection molds have multi-cavity runner system for mass production, which are designed with geometrically balanced runner system in order to accomplish filling balance between cavity to cavity during processing. However, even though geometrically balanced runner is used, filling imbalances have been observed. So, many studies for improving filling balance in the multi-cavities molds are worked up. In this study, the Melt-Buffer which is a new runner system for filling balance has been suggested, and a series of experiment about degree of filling balance in cavity-to-cavity was conducted in the mold with the Melt-Buffer. From the experiment, the filling balance was increased up to 5~6% by using the Melt-Buffer.
장민규,김창진,최해석,정영득,Jang, Min-Kyu,Kim, Chang-jin,Choi, Hea-Suck,Jeong, Yeong-Deug 한국금형공학회 2015 한국금형공학회지 Vol.9 No.2
In injection molding, many kinds of defects have occurred because of a characteristic of plastics injection molding. Weld line is one of the defects is formed when separated melt fronts recombine together during the mold filling stage. That is one of problems in injection molding. Weld lines in the appearance of plastics parts can deteriorate visible quality. And most importantly, the local mechanical strength in the weld line area can be significantly weaker. It could be one of the most problems for structural applications. In this study, the mold available two-shot-molding of same polymers have been designed, and a series of experiment about tensile strength in weld line area has been conducted using Taguchi's design of experiment to optimize injection molding conditions decreasing of weld strength and find out a factors affected weld strength in two-shot- molding.
다수 캐비티를 갖는 핫러너 금형에서의 균형충전을 위한 자동제어시스템
장민규,조일규,이옥성,정영득,Jang, Min-Kyu,Jo, Il-Kyu,Lee, Ok-Seong,Jeong, Yeong-Deug 한국금형공학회 2015 한국금형공학회지 Vol.9 No.1
For mass production of plastics, injection molds have multi-cavities. However, filling imbalance between cavity to cavity always has occurred in multi-cavities mold, and this has caused low quality of plastics part. In this study, the closed-loop-control system which can control temperature of hot manifold and nozzle in hot runner mold for filling balance has been suggested, and a series of experiment about difference of filling time and weight in cavity-to-cavity was conducted. As a result of using closed-loop-control system, a remarkable improvement in reducing filling imbalance was confirmed.
사출금형의 러너시스템 형상에 따른 충전불균형 유동해석 모델
장민규,고승우,김영민,노병수,정영득,Jang, Min-Kyu,Go, Seung-Woo,Kim, Yeong-Min,Noh, Byeong-Su,Jeong, Yeong-Deug 한국금형공학회 2008 한국금형공학회지 Vol.2 No.5
Almost all injection molds have multi-cavity runner system for mass production, which are designed with geometrically balanced runner system in order to accomplish filling balance between cavity to cavity during processing; However, even though geometrically balanced runner is used, filling imbalances have been observed. In these day, the CAE has been used widely in injection molding. However, CAE with fusion mesh can't indicate such as jetting, flow mark and filling imbalance in multi cavity mold. In this study, we investigated the filling imbalance according to runner shapes by CAE analysis. As a result in CAE, in case of binary branch runner system, filling imbalance was indicated between cavity to cavity, but the flow pattern of each cavity uniformed in unary branch runner system.
장민규(Min-Kyu Jang),Yan-Jiating,정영득(Yeong-Deug Jeong),곽재섭(Jae-Seob Kwak) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
BMT turret is an indispensable part in CNC lathe turning center. A good driving ASS'Y in BMT turret can improve productivity by reducing tool changeover time. With this in mind, it is essential to design the BMT driving ASS'Y to meet the ever-increasing demand of precision machine tools. In this study, a simulation-based multi-objective design optimization methodology was implemented to improve the efficiency of BMT driving ASS'Y. First, three-dimensional finite element structural and vibration analysis were performed by using ANSYS/Workbench on the initial geometric models of BMT driving ASS'Y. After analyzing stress and deformation concentration zones, several new geometrical models were designed and evaluated by design of experiment and ANSYS/DesignXplorer. Through a series of analysis-evaluation-modification cycles, it was found that designed geometric models were effectively in determining optimal geometric sizes of BMT driving ASS'Y.
탄소 및 탄소화합물이 도핑된 $MgB_2$ 초전도체의 볼밀링 효과
안중호,장민규,오상준,Ahn, Jung-Ho,Jang, Min-Kyu,Oh, Sang-Jun 한국초전도학회 2008 Progress in superconductivity Vol.10 No.1
We have examined the effect of ball-milling on the superconducting properties of $MgB_2$ doped with C. The ball-milling of pre-reacted $MgB_2$ powder was carried out in dry or wet state using C or diethylenetriamine ($C_{4}H_{13}N_3$) as additives. The diethylenetriamine, whose chemical formula contains no oxygen, was chosen to avoid an excess oxidation during doping. The superconducting transition temperature (Tc) of the ball-milled or doped $MgB_2$ powders was only slightly smaller than that of undoped $MgB_2$. The critical current density (Jc) of the highly ball-milled $MgB_2$ was higher than that of C-doped $MgB_2$. The addition of diethylenetriamine was detrimental to Jc, although Tc was almost unchanged.
안중호,장민규,Ahn, Jung-Ho,Jang, Min-Kyu 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.3
Carbon nanotube (CNT)/$Mg_2Ni$ composites were synthesized to enhance the hydrogen storage properties. The emphasis was made on the effect of different shortening methods of CNTs on the open-tip structure and the resulting properties. The use of open CNTs as a starting material resulted in an enhanced hydrogen properties of CNT/$Mg_2Ni$ composites. Among the employed methods for the shortening of CNTs, wet milling using ethanol was the most efficient, while ultrasonic acid treatment or thermal decomposition resulted in a less hydrogen storage capacity.
노건철,장민규,제덕근,최윤식,정영득,Noh, Keon-Cheol,Jang, Min-Kyu,Je, Deok-Keun,Choi, Yoon-Sik,Jeong, Yeong-Deuk 한국금형공학회 2014 한국금형공학회지 Vol.8 No.1
Plastic products are producted more than 70% of total processes by the injection molding. The injection molding process has 4 processes such as filling, packing, cooling and ejecting. It spends most of times in the cooling process. Therefore, it is important to control the mold temperature in producing plastic products. The time and system of cooling affect the product's quality and productivity. Especially, cooling time has about 60% of total injection cycle time. Therefore, we can improve a productivity by shortening cooling time. This study shows comparative study about cooling efficiency of spiral channel and baffle and observed the variation of time to freeze of molding As the result of CAE experiments, cooling rate by spiral channel had faster than baffle and as freeze time was decreased. Results of this study will be used widely to design for cooling system of injection mold.
김영모,박영민,장민규,정영득,Kim, Young-Mo,Park, Yeong-Min,Jang, Min-Kyu,Jeong, Yeong-Deug 한국금형공학회 2012 한국금형공학회지 Vol.6 No.2
Weld line in injection molded part is one of the defects in injection molding process. Weld line deteriorates not only appearance quality but mechanical property. In this study, ABS and PP were used as experimental materials. And weld line length, depth and strength have been examined according to the injection molding conditions. As the results of experimental studies, weld line length increased as flow rate increases for all materials. And the flow rate is most influenced to the creation of weld line length. Also weld line strength increased, as flow rate and melt temperature increase for all materials. The whole experiment results was similar to CAE analysis results.
노건철,이규호,장민규,정영득,Noh, Keon-Cheol,Lee, Gyu-Ho,Jang, Min-Kyu,Jeong, Yeong-Deug 한국금형공학회 2015 한국금형공학회지 Vol.9 No.1
The injection molding is used in more than 70% of total production of plastic products. Weld line in injection molded part is one of the defects in injection molding process. Weld line deteriorates not only appearance quality but also mechanical property. In this study, tensile strength about material such as ABS, PP, PA and PS was tested. as the results, the first result appears that weld's strength retention ratio's are 0.90, 0.84, 0.85, 0.76 and the second result apeears that weld depth decrease as processing temperature increased.