• Title/Summary/Keyword: 주형충전

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Development of an implicit filling algorithm (암시적 방법을 이용한 충전 알고리즘의 개발)

  • Im, Ik-Tae;Kim, U-Seung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.1
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    • pp.104-112
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    • 1998
  • The mold filling process has been a central issue in the development of numerical methods to solve the casting processes. A mold filling which is inherently transient free surface fluid flow, is important because the quality of casting highly depends on such phenomenon, Most of the existing numerical schemes to solve mold filling process have severe limitations in time step restrictions or Courant criteria since explicit time integration is used. Therefore, a large computation time is required to analyze casting processes. In this study, the well known SOLA-VOF method has been modified implicitly to simulate the mold filling process. Solutions to example filling problems show that the proposed method is more efficient in computation time than the original SOLA -VOF method.

A Study on the Filling and Solidification Process During Gravity Casting Using Implicit VOF Method (암시적 VOF법을 이용한 중력주조에서의 충전 및 응고과정에 대한 연구)

  • Im, Ik-Tae;Kim, Woo-Seung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.1
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    • pp.102-113
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    • 2000
  • In this study, a three-dimensional gravity casting problem has been examined to investigate a coupled phenomenon of the filling and solidification process. This work simultaneously considers the two key phenomena of metal casting : the fluid flow during mold filling, and solidification process. The VOF method is used to analyze the free surface flow during filling and the equivalent specific heat method is employed to model the latent heat release during solidification. The time-implicit filling algorithm is applied to save the computational time for analyzing the mold filling process. The three-dimensional benchmark problem used in the MCWASP VII has been solved using both the implicit and explicit algorithm, and the present results are compared with the benchmark experimental results and the other numerical results.

A Study of a Simultaneous Filling and Solidification During Casting Process (충전과 상변화 현상을 포함한 주조과정에 대한 연구)

  • Im, lk-Tae;Kim, Woo-Seung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.8
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    • pp.987-996
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    • 1999
  • An algorithm for modeling the filling of metal into a mold and solidification has been developed. This algorithm uses the implicit VOF method for a filling and a general implicit source-based method for solidification. The model for simultaneous filling and solidification is applied to the two-dimensional filling and solidification of a square cavity. The effects of the wall temperature and gate position on the solidification are examined. The mixed natural convection flow and residual flow resulting from the completion of a filling are included in this study to investigate the coupled effects of the filling and natural convection on solidification. Two different filling configurations (assisting flow and opposite flow due to the gate position) are analysed to study the effects of residual flow on solidification. The results clearly show the necessity to carry out a coupled filling and solidification analysis including the effect of natural convection.

Improvement of Electrical and Mechanical Property of Epoxy Resin Insulator (에폭시 수직 절연물의 전기적 기계적 특성 향상)

  • Kim, Ji-Hwan;Ha, Young-Kil;Park, Hyun-Deuk;Jeon, Seung-Ik
    • Proceedings of the KIEE Conference
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    • 2001.11a
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    • pp.262-264
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    • 2001
  • 에폭시 수지는 전기적 기계적 특성이 좋기 때문에 전기기기 분야에서 주요 절연 재료로 널리 사용되고 있다. 에폭시 수지는 일반적으로 경화제 및 충전재를 첨가하여 경화반응을 거쳐 최종 주형품을 얻게 되며 첨가되는 경화제 및 충전재에 따라 그 전기적 기계적 특성이 달라지게 된다. 본 연구에서는 충전재의 입도 크기 및 형상 등이 에폭시 수지 절연물의 전기적 기계적 특성에 미치는 영향을 실험하고 분석한 결과 충전재의 입도 크기가 작아짐에 따라 기계적 특성이 매우 우수하고 충전재의 형상이 구상일 경우 전기적 기계적 특성이 향상되는 것을 알 수 있었다.

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Preparation of Molecularly Imprinted Poly(methacrylic acid) and Its HPLC Separation Characteristics of Retinoids (분자각인 Poly(methacrylic acid)의 제조 및 레티노이드 화합물의 HPLC 분리 특성)

  • 남기훈;권영돈;김덕준
    • Polymer(Korea)
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    • v.26 no.6
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    • pp.710-717
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    • 2002
  • Molecularly imprinted polymers were prepared in particle forms by crosslinking methacrylic acid (MAA)) using all trans-retinoic acid as a template. The HPLC column packed with the prepared molecular imprinted polymers showed high capability in separation of retinoid derivatives. The column capacity factor and selectivity increased with increasing MAA to template ratio when the incorporated template amount was fixed, as it statistically generated more binding sites between host molecules and template. Molecularly imprinted polymer particles prepared via an emulsion polymerization method were round-shaped and their sizes were more uniformly distributed, but their separation capability was inferior to those obtained by solution polymerization method. It was presumably because the loss of interaction strength between MAA and the template due to hydrogen bonding either between MAA and water or between template and water during the synthesis of molecularly imprinted polymers.

Effects of Nano-Sized Inorganic Fillers on Polymerization and Thermal Degradation of Polyurethane Composites (나노사이즈 무기분말이 폴리우레탄복합체의 중합 및 열분해반응에 미치는 영향)

  • Lee, Joon-Man;Ahn, Won-Sool
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.3
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    • pp.1027-1034
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    • 2010
  • Effects of inorganic nano-powders on the polymerization and thermal degradation kinetics as well as the mechanical properties of polyurethane nano-composites were studied by both the measurement of polymerization temperature as a function of time and non-isothermal thermogravimetric analysis (TGA) as well as the Instron test. As the results from polymerization studies, the reaction rates of MMT-filled PU composites were faster than those of Ce500-filled ones, and moreover, the activation energies using Kissinger method for the thermal degradation of composites were calculated as 139.34 kJ/mol for the Ce500-filled PU composites and 91.12 kJ/mol for MMT-filled one, respectivel, exhibiting that MMT nano-powder seemed to be acting as the catalyst for both polymerization and degradation of PU composites. UTM result, however, showed that tensile strength at break of MMT-filled composites was much higher than that of Ce500-filled ones above the concentrations range of 5 phr in the composites.

Mold Cavity Filling by Gating Design in Vacuum Molding Process (진공흡입주형 주조법에서 탕구방안에 따른 주형 충전 양상)

  • Kang, Bok-Hyun;Kim, Ki-Young;Kim, Myung-Han;Hong, Young-Myung
    • Journal of Korea Foundry Society
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    • v.27 no.1
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    • pp.42-47
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    • 2007
  • Vacuum molding process(V-process) has several benefits such as a lower total production cost and a high quality casting comparing to the conventional sand molding. Influence of the gating design on the molten metal flow was investigated in this study. General criteria for the gating design of the castings and commercial codes for the flow and solidification analysis were used to attain the optimized gating design in V-process. Though mold cavity was filled smoothly under the low initial velocity of molten metal, molten metal dashed against the upper part of the mold before the completion of the mold filling with higher initial molten metal velocity and fell soon. This phenomenon may affect collapsing the mold shape, however it is thought that the possibility of burning out of the vinyl by the molten metal is not so high because vinyl is coated with refractory material.

VR Visualization of Casting Flow Simulation (주물 유동해석의 VR 가시화)

  • Park, Ji-Young;Suh, Ji-Hyun;Kim, Sung-Hee;Kim, Myoung-Hee
    • 한국HCI학회:학술대회논문집
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    • 2008.02a
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    • pp.813-816
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    • 2008
  • In this research we present a method to reconstruct the casting flow simulation result as a 3D model and visualize it on a VR display. First, numerical analysis of heat flow is performed using an existing commercial CAE simulation software. In this process the shape of the original design model is approximated to a regular rectangular grid. The filling ratio and temperature of each voxel are recorded iteratively by predefined number of steps starting from pouring the melted metal into a mold until it is entirely filled. Next we reconstruct the casting by voxels using the simulation result as an input. The color of voxel is determined by mapping the colors to temperature and filling ratio at each step as the flow proceeds. The reconstructed model is visualized on the Projection Table which is one of horizontal-type VR display. It provides active stereoscopic images.

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Mechanical Properties and Mold Filling Capability of Al-Si-Mg Casting Alloy Fabricated by Lost Foam Casting Process (소실모형주조공정으로 제조한 Al-Si-Mg계 주조합금의 기계적 성질 및 주형 충전성)

  • Kim, Jeong-Min;Ha, Tae-Hyung;Choe, Kyeong-Hwan
    • Journal of Korea Foundry Society
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    • v.36 no.5
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    • pp.153-158
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    • 2016
  • The lost foam casting process was used to fabricate Al-Si-Mg cast specimens, and the effects of the chemical composition and process variables on the tensile properties and the mold filling ability were investigated. Some porosity formation was observed in thick sections of the casting and better tensile properties were obtained for thin sections, presumably because of their lower porosity and the higher cooling rate. Tensile properties were not clearly enhanced by grain refining treatment with Ti; however, the elongation was significantly improved by Sr modification of the Al-Si-Mg alloy. The mold filling distance was generally proportional to the pouring temperature of the melt, and the distance was also increased by the addition of Ti.

Structural Behavior of Flexurally Reinforced FRP-Concrete Composite Compression Member with FRP (FRP로 휨보강된 FRP-콘크리트 합성압축재의 구조적 거동)

  • Park, Joon-Seok;Joo, Hyung-Joong;Nam, Jeong-Hun;Yoon, Soon-Jong
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.1 no.3
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    • pp.10-16
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    • 2010
  • In construction industries, new construction materials are needed to overcome some problems associated with the use of conventional construction materials due to the change of environmental and social requirements. Accordingly, the requirements to be satisfied in the design of civil engineering structures are diversified. As a new construction material in the civil engineering industries, fiber reinforced polymeric plastic (FRP) has a superior corrosion resistance, high specific strength/stiffness, etc. Therefore, such properties can be used to mitigate the problems associated with the use of conventional construction materials. Nowadays, new types of bridge piers and marine piles are being studied for new construction. They are usually made of concrete filled fiber reinforced polymeric plastic tubes (CFFT). In this paper, a new type of FRP-concrete composite pile which is composed of reinforced concrete filled FRP tube (RCFFT) is proposed to improve compressive strength as well as flexural strength. The load carrying capacity of proposed RCFFT compression member is discussed based on the result of experimental and analytical investigations.

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