• 제목/요약/키워드: Solidification path

검색결과 14건 처리시간 0.029초

마이크로 광 조형기술에서 수지경화현상을 고려한 레이저 주사경로 생성 (Generation of Laser Scan Path Considering Resin Solidification Phenomenon in Micro-stereolithography Technology)

  • 조윤형;조동우
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 추계학술대회 논문집
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    • pp.1037-1040
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    • 2002
  • In micro-stereolithography technology, fabrication conditions that include laser power, laser scan speed, laser scan pitch, and material property of photopolymer such as penetration depth and critical exposure are considered as major process variables. But the existing scan path generation methods based only on CAD model have not taken them into account, which has resulted in cross-section dimension of low accuracy. Thus, to enhance cross-section dimensional accuracy, the physical resin solidification n phenomena should be reflected in laser scan path generation and stage operating code. In this paper, multi-line experiments based on single line solidification model are performed. And the method for improving cross-section dimensional accuracy is presented, which is to apply the database based on experimental results to laser scan path generation.

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Al-Si-Fe 3원계 조성의 응고경로 예측 및 실험적 검증 (Prediction of Solidification Path in Al-Si-Fe Ternary System and Experimental Verification)

  • 이상환;이상목
    • 한국주조공학회지
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    • 제30권1호
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    • pp.34-45
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    • 2010
  • The effects of alloy elements and cooling rate on the solidification path and the formation behavior of $\beta$ phase in Fe-containing Al-Si alloys were studied based on the thermodynamic analysis and the pertinent experiments. The thermodynamic calculation was systematically performed by using Thermo-Calc program. For the thermodynamic analysis in high alloy region of Al-Si-Fe ternary system, a thermodynamic database for Thermo-Calc was correctly updated and revised by the collected up-to-date references. For the thermodynamic-based prediction of various solidification paths in Fe-containing Al-Si system, liquidus projection of Al-Si-Fe ternary system, including isotherms, invariant, monovariant, bivariant reactions and equilibrium temperatures, was calculated and analyzed as functions of composition and temperature. The calculated results were compared to the experimental results using various casting specimens. In order to analyze various solidification sequences as functions of Si and Fe content, 4 representative alloy compositions, low Fe content in both low and high Si contents and high Fe content again in both low and high Si contents, were designed in this study. For better understanding of the influence of cooling rate on the formation behavior of $\beta$ phase, 4 alloys were solidified under furnace and rapidly cooled conditions. Cooling curves of solidified alloys were recorded by thermal analysis. Various important solidification events were evaluated using the first derivative-cooling curves. Microstructures of the casting samples were studied by the combined analysis of optical microscopy (OM) and scanning electron microscopy (SEM).

역류방지 체크밸브의 응고해석 특성 (Solidification Analysis Characteristics of Back Flow Prevention Check Valve)

  • 윤정인;문정현;손창효;이정진
    • 동력기계공학회지
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    • 제19권3호
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    • pp.69-74
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    • 2015
  • Check valves used in vessels include shock-release function on piping system, aside from basic back flow prevention. However, proper and enough protection of system is not obtainable due to use of high-pressure and bulk fluids, resulting from enlargement of vessels. In this study, casting analysis of check valves protecting systems in flow path from water hammering or back flow is conducted, using Z-CAST program. Also, molten metal filling, flow analysis, solidification analysis and shrinkage cavity analysis are conducted. The main results are as following. Regarding filling of each risering, molten metal showed stable supply condition without being isolated. It was identified that the final solidification exists on risering, but shrinkage cavity possibly might happens at the point of isolation solidification.

이종 PCM의 선택적 상변화 시의 열전달 해석 (Numerical Study of Heat Transfer with Selective Phase Change in Two Different Phase Change Materials)

  • 김형국;이동규;백종현;강채동
    • 설비공학논문집
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    • 제25권9호
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    • pp.477-483
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    • 2013
  • A numerical analysis of solid-liquid phase change was performed on a heat transfer module which consisted of circulating water path (BRINE), heat transfer plate (HTP) and phase change material (PCM) layers, such as high temperature PCM (HPCM, $78{\sim}79^{\circ}C$) and low temperature PCM (LPCM, $28{\sim}29^{\circ}C$). There were five arrangements, consisting of BRINE, HTP, LPCM and HPCM layers in the heat transfer module. The time and heat transfer rate for melting/solidification was compared to their arrangements, against each other. As results, the numerical time without convection was longer than the experimental one for melting/solidification. Moreover, the melting/solidification with the BRINE I-LPCM-BRINE II-HPCM arrangement was faster(10 hours) than the others; HPCM-BRINE-LPCM, BRINE I-HPCM-LPCM-BRINE II one.

급속응고된 TiAl 금속간화합물의 Al함량 변화에 따른 미세조직변화에 관한 연구 (A Study on the Microstructures of Rapidly Solidified Ti-($45{\sim}58at%$)Al Intermetallic Compound)

  • 김재훈;정태호;남태운
    • 한국주조공학회지
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    • 제18권6호
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    • pp.550-554
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    • 1998
  • The microstructures of rapidly solidified binary Ti-Al alloys containing $45{\sim}58\;at%Al$ have been studied using C/S (carbon/sulfur), N/O (nitrogen/oxygen) analyser, X-ray fluorescence spectrometer (XRF), X-ray diffractometer (XRD), optical microscope (OM) and scanning electron microscope (SEM). The phases present in the alloys and their distribution were found to be a sensitive function of Al content. Essentially single-phase (${\gamma}$) microstructures were observed to alloys with 45 at%Al, 55 at%Al and 58 at%Al. In other content alloys, two phase (${\alpha}_2$, ${\gamma}$) microstructures were observed. The 48 at%Al, 52 at%Al alloys contain (${\gamma}+{\alpha}_2$) phase and ${\alpha}_2$ phase. These results indicate that rapid solidification affect the solidification path, then metastable phase forming during solidification.

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Characterization of Solidification and Microstructure of an Al-Zn-Mg-Si Alloy

  • He Tian;Dongdong Qu;Zherui Tong;Nega Setargew;Daniel J. Parker;David StJohn;Kazuhiro Nogita
    • Corrosion Science and Technology
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    • 제23권2호
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    • pp.104-112
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    • 2024
  • Al-Zn-Mg-Si alloy coatings have been developed to inhibit corrosion of cold rolled steel sheets, and an understanding of the alloy system helps prevent coating defects. We used a Bridgman furnace to characterise the nature and formation mechanisms of the phases present in the quaternary system with 0.4 wt% Fe. In the directional solidification experiments we imposed steep temperature gradients and varied the pull rate. After the samples were quenched in the furnace, detailed characterization of the samples was carried out by electron microscopy (SEM/EDS). From the dT/dt vs T plots of the cooling curves of the alloys, the solidification path was determined to be $Liquid{\longrightarrow[80]^{544-558}}{\alpha}-Al{\longrightarrow[80]^{453-459}}Al/Mg_2Si{\longrightarrow[80]^{371-374}}Al/Zn{\longrightarrow[80]^{331-333}}Zn/mgZn_2$. The formation mechanisms of the Mg and Zn containing phases and their morphology was discussed together with the effects of the cooling rate. Key findings include the lengthening of the mushy zone in directionally solidified samples remelted against a positive temperature gradient, as well as an enrichening of the α-Al phase by Zn through remelting. Mg2Si and other Si based phases were observed to adopt a much finer faceted microstructure in favour of a script-like microstructure when exposed to the higher cooling rate of coolant quenching.

3 차원 형상의 미소제품 제작을 위한 마이크로 광 조형시스템의 개발 (Development of micro-stereolithography system for the fabrication of three-dimensional micro-structures)

  • 이인환;조윤형;조동우;이응숙
    • 한국정밀공학회지
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    • 제21권2호
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    • pp.186-194
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    • 2004
  • Micro-stereolithography is a newly proposed technology as a means that can fabricate a 3D micro-structure of free form. It makes a 3D micro-structure by dividing the shape into many slices of relevant thickness along horizontal surfaces, hardening each layer of slice with a focused laser beam, and stacking them up to a desired shape. In this technology, differently from the conventional stereolithography, scale effect is dominant. To realize micro-stereolithography technology, we developed the micro-stereolithography apparatus which is composed of an Ar+ laser, x-y-z stages. controllers. optical devices and scan path generation software. Related processes were developed, too. Using the system, a number of micro-structures were successfully fabricated. Some of these samples are shown for prove this system. Laser scan path generation algorithm and software considering photopolymer solidification phenomena as well as given 3D model were developed. Sample fabrication of developed software shows relatively high dimensional accuracy compared to the uncompensated result.

냉열잠열축열조의 성능해석 (Performance of the Cold Latent Storage System)

  • 윤호식;노승탁
    • 대한설비공학회지:설비저널
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    • 제17권4호
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    • pp.456-465
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    • 1988
  • The performance of the cold latent heat storage is investigated by experiment and by a simplified analytic approach. The heat storage tank has eight horizontal circular tubes and one path of refrigerant evaporating tube. The phase change material in the heat storage tank is water which is frozen by evaporating refrigerant of refrigeration system and melts by the warm air in the heat storage tank. In the experiment, the performance has been studied by the various conditions including the initial water temperature on solidification and flow rate and temperature of air. The rate of recovered heat has been simulated by a simplified model and the results shows a good agreement. In solidification process, initial water temperature causes time delay corresponding to the sensible heat and it is found that the shape of evaporator is important. In melting process, the recovered heat rate from the heat storage tank is proportional to $Re^{0.8}(T_{bi}-T_f)$ of air where $T_{bi}$ and $T_f$ indicate temperatures of inlet air and phase change, respectively. And the deminishing rate of the recovered heat is higher for the higher heat rate.

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주형의 전산기 원용 설계 II -팅구계와 주형캐비티의 설계- (Computer Aided Design of a Mold Cavity with Proper Rigging System for Casting Processes(II))

  • 박종천;이건우
    • 대한기계학회논문집
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    • 제14권2호
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    • pp.376-381
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    • 1990
  • An interactive computer program to design a mold cavity with the proper rigging system has been developed. In addition to the pattern and the risers generated in part 1 of this work, the various components of the gating system are generated in complete three dimensional models by a rational approach. Then they are laid interactively by the user, and united together with the pattern and the risers to result in the three dimensional model of the mold assembly. Finally, the vents and the mold box are constructed following the user's interactive specification and then the mold cavity is completed in a three dimensional geometric model by subtraction the mold assembly and the vents from the mold box. The three dimensional model of a mold cavity is useful for many related applications such as the solidification simulation for mold evaluation and the NC tool path generation for mold production.

Fe-Co-W 소결체와 탄소강의 레이저 용융부 결함형성에 미치는 공정변수의 영향 (The effect of welding parameters on the formation of discontinuities in the laser fusion zone between Fe-Co-W sintered segment and mild steel)

  • 김성욱;윤병현;정우광;이창희
    • 한국레이저가공학회지
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    • 제7권3호
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    • pp.25-36
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    • 2004
  • This study was performed to clarification of the formation of weld discontinuities in the dissimilar laser fusion zone. Welding parameters were beam power of 1300, 1430, 1560, and 1700 W and travel speed of 1, 1.3, and 1.7 m/min. Most cavities in the fusion zone were observed near the tip. Cavities in the fusion zone observed to be formed and grown from pores in the tip. More cavities were formed as the beam position moves to the tip side. Small cavities were decreased but large cavities were increased when the energy input increased. W content in the fusion zone was increased with heat input and as the beam position close to the tip. In the fusion zone, W content in the dendrite boundary was increased with heat input. Considering the propagation path and fracture morphology, cracks were solidification cracking, and were initiated and propagated along the dendrite boundaries. The formation of cracks might be related with the W rich ${\mu}$ phase which was formed in the grain boundaries and dendrite boundaries.

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