• Title, Summary, Keyword: rheology

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The Manufacture of Aluminum Rheology Materials by Spiral Stirring Equipment (나선형 기계 교반 장치를 이용한 Al 합금 레오로지 소재의 제조)

  • Han, S.H.;Bae, J.W.;Kang, C.G.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.397-400
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    • 2007
  • Recently, rheology forming technology has been interested in industrial and academic for light weight materials and to solve environmental issues. In this study, the rheology material production equipments were used to be made spiral shape by special design. And the experiment variables established stirring time 0 $\sim$ 1200 sec, stirring velocity 0 $\sim$ 100 rpm and several material temperature of semi - solid states. The rheology materials were made for established experiment conditions then measured mechanical properties. Sequence-production equipments were appended to fabrication system of rheology material for make rheology materials continually. Therefore, the development of sequence-production equipments were demanded for fine grains and for uniform globule shape rheology materials by a specially designed spiral stirrer machine.

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High-pressure rheology of polymer melts containing supercritical carbon dioxide

  • Lee Sang-Myung;Han Jae-Ro;Kim Kyung-Yl;Ahn Young-Joon;Lee Jae-Wook
    • Korea-Australia Rheology Journal
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    • v.18 no.2
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    • pp.83-90
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    • 2006
  • Supercritical carbon dioxide ($scCO_2$) has advantages of being incorporated in polymer with high solubility and of being recovered easily by depressurizing. $scCO_2$ reduces the viscosity of polymer melt and it is expected to be use as a plasticizing agent. In this work, we studied on the effect of $scCO_2$ on the rheological properties of polymer melts during extrusion process. Slit die attached to twin screw extruder was used to measure the viscosity of polymer melts plasticized by supercritical $CO_2$. A gas injection system was devised to accurately meter the supercritical $CO_2$ into the extruder barrel. Measurements of pressure drop within the die, confirmed the presence of a one phase mixture and a fully developed flow during the measurements. The viscosity measurement of polypropylene was performed at experimental conditions of various temperatures, pressures and $CO_2$ concentrations. We observed that melt viscosity of polymer was dramatically reduced by $CO_2$ addition.

Research Trends of Rheology Forming and Their Solutions to Mass Production (금속레오로지 소재성형의 연구동향 및 대량생산을 위한 해결 방안)

  • 강충길
    • Transactions of Materials Processing
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    • v.11 no.2
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    • pp.123-131
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    • 2002
  • The rheology process is net shape manufaturing technology to high of automobile part and improve the mechanical properties. For the rheology forming process, Phase and globular microstructure are very important. The equipments to make a rheology alloys with slurry statement have been introduced. Therefore, the Problems to Produce a rheology alloyas with continuous process had also been investigated to make Production in industries. The validity of the introduced rheology Process is investigated by comparing the reported thixoforming results. Therefore, the many advantage of rheology process to be reduced the reheating Process and billet fabrication method has been expressed in terms of mass production, in the future.

Development of Rheology Forming Technology of Wear Resistance Al-Si Materials (I);Filling Behavior and Defect Evaluation (내마모계 Al-Si 재료의 레오로지 성형기술 개발 (I);충진거동 및 결함분석)

  • Jung, Hong-Kyu;Kang, Sung-Soo;Moon, Young-Hoon;Kang, Chung-Gil
    • Journal of Korea Foundry Society
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    • v.20 no.6
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    • pp.368-376
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    • 2000
  • Rheology forming technology has been accepted as a new method for fabricating near net shaped products with lightweight aluminum alloys. The rheology forming process consists of reheating process of billet, billet handling, filling into the die cavity and solidification of rheology formed part. The rheology forming experiments are performed with two different die temperatures ($T_d$ = $200^{\circ}C$, $300^{\circ}C$) and orifice gate type. The filling behavior and various defects of Al-Si materials with wear resistance (A357, A390 and ALTHIX 86S) fabricated in rheology forming process are evaluated in terms of alloying elements and surface non-uniformity. Finally, the methods to obtain the rheology formed products with high quality are described by solutions for avoiding the surface and internal defects.

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A review on viscocapillary models of pre-metered coating flows

  • Youn, Suk-Il;Kim, Su-Yeon;Shin, Dong-Myeong;Lee, Joo-Sung;Jung, Hyun-Wook;Hyun, Jae-Chun
    • Korea-Australia Rheology Journal
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    • v.18 no.4
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    • pp.209-215
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    • 2006
  • Recent research results on viscocapillary models of various pre-metered coating flows such as curtain, slide, and slot coatings have been reviewed in this paper. Such one-dimensional models have been simplified from two-dimensional Navier-Stokes equations for viscous coating flows with free surfaces, using integral momentum balances and lubrication approximation. It has been found that these viscocapillary models is capable of predicting flow dynamics in various coating systems, providing the good agreement with results by 2-D models.

In-line measurement of residence time distribution in twin-screw extruder using non-destructive ultrasound

  • Lee, Sang-Myung;Park, Jong-Cheol;Lee, Sang-Mook;Ahn, Young-Joon;Lee, Jae-Wook
    • Korea-Australia Rheology Journal
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    • v.17 no.2
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    • pp.87-95
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    • 2005
  • In this study, we performed RTD measurement at the die exit of co-rotating twin-screw extruder using a non-destructive ultrasonic device. The ultrasonic device was attached at slit die and was composed of a steel buffer rod and 10 MHz longitudinal piezoelectric ultrasonic transducer. This in-line ultrasonic monitoring method is based on the ultrasonic response of $CaCO_3$ filled in polymer. The RTD is evaluated by variation of ultrasonic attenuation with time caused by change of the tracer concentration during extrusion. The ultrasonic tracer, pellet type of compounded $CaCO_3$ in polymer was used in this study. The effects of tracer concentration on RTD and flow patterns were studied. Evaluation for the residence functions at different screw speeds, feeding rates and screw configurations were also carried out.