• Title/Summary/Keyword: Extrusion Die

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Microstructure and High-Cycle Fatigue Properties of High-Speed-Extruded Mg-5Bi-3Al Alloy (Mg-5Bi-3Al 마그네슘 고속 압출재의 미세조직과 고주기피로 특성)

  • Cha, J.W.;Jin, S.C.;Park, S.H.
    • Transactions of Materials Processing
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    • v.31 no.5
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    • pp.253-260
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    • 2022
  • In this study, the microstructural characteristics of a high-speed-extruded Mg-5Bi-3Al (BA53) alloy and its tensile, compressive, and high-cycle fatigue properties are investigated. The BA53 alloy is successfully extruded at a die-exit speed of 16.6 m/min without any hot cracking using a large-scale extruder for mass production. The homogenized BA53 billet has a large grain size of ~900 ㎛ and it contains fine and coarse Mg3Bi2 particles. The extruded BA53 alloy has a fully recrystallized microstructure with an average grain size of 33.8 ㎛ owing to the occurrence of complete dynamic recrystallization during high-speed extrusion. In addition, the extruded BA53 alloy contains numerous fine lath-type Mg3Bi2 particles, which are formed through static precipitation during air cooling after exiting the extrusion die. The extruded BA53 alloy has a high tensile yield strength of 175.1 MPa and ultimate tensile strength of 244.4 MPa, which are mainly attributed to the relative fine grain size and numerous fine particles. The compressive yield strength (93.4 MPa) of the extruded BA53 alloy is lower than its tensile yield strength, resulting in a tension-compression yield asymmetry of 0.53. High-cycle fatigue test results reveal that the extruded BA53 alloy has a fatigue strength of 110 MPa and fatigue cracks initiate at the surface of fatigue test specimens, indicating that the Mg3Bi2 particles do not act as fatigue crack initiation sites. Furthermore, the extruded BA53 alloy exhibits a higher fatigue ratio of 0.45 than other commercial extruded Mg-Al-Zn-based alloys.

Characterization of Color Change in Injection Molding Process Using Hot Runner (핫 러너 사출 공정에서 수지의 색 교체 특성 연구)

  • Hong, Ji Sun;Shim, Hee Soo;Lee, Ji-Hyun;Kwon, Min-Kyung;Chung, Dong-Il;Kim, Sun Kyoung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.1
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    • pp.111-115
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    • 2015
  • In injection molding process using hot runners, color change is a critical issue. This work proposes a method of assessing the color change characteristics of thermoplastics polymers. A method that utilizes a capillary die to measure degree of color change has been devised and implemented. The extrudate from the capillary die has been imaged and quantized to a gray scale value. Based on the gray scale value, the degree of color change has been determined. Under given temperatures and extrusion velocity, its trend along with the number of extrusion has been obtained and analyzed.

Effect of Die Temperature and Dimension on Extract Characteristics of Extruded White Ginseng (사출구 온도와 구조에 따른 압출성형 백삼의 추출 특성)

  • Kim, Bong-Su;Ryu, Gi-Hyung
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.34 no.4
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    • pp.544-548
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    • 2005
  • The objective of this study was to determine the effect of die temperature and dimension on extraction pattern, extract yield, and crude saponin content of extruded white ginseng. The extrusion variables were die temperature $(110\;and\;120^{\circ}C)$ and die dimension (3 holes with 1.0 mm, 2 holes with 2.0 mm, and 1 hole with 3.0 mm diameter). The browness and redness were indicator of active components in ginseng extract. Both were used to evaluate the effect of die temperature and die dimension on release pattern and release rate constant. Browness and redness of extract achieved its lowest value at die temperature $110^{\circ}C$ and 2 holes with 2.0 mm diameter, indicating the lowest extraction rate constant. Extract yield highly increased by extrusion treatment. Extract yield and crude saponin content were the highest at die temperature $120^{\circ}C$ and 1 hole with 3.0 mm diameter. In conclusion, extrusion process has contributed significantly in improvement of release rate of its active components.

Effect of Extrusion Temperature on Puffing of White and Red Ginseng (압출성형 온도가 백삼과 홍삼의 팽화에 미치는 영향)

  • Kim, Bong-Su;Ryu, Gi-Hyung
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.34 no.7
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    • pp.1109-1113
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    • 2005
  • The objective of this study was to determine the effect of extrusion temperature on puffing of white and red ginseng powder. The extrusion variables were feed material (red and white ginseng powder) and die temperature $(100\;and\;115^{\circ}C)$. The analyzed characteristics of ginseng extrudates were sectional expansion index, microstructure and rheological properties. Most of biopolymer was highly puffed at higher extrusion temperature, but the cross-sectional expansion of white and red ginseng powder was higher at 1000e and longitudinal expansion seems to higher at $115^{\circ}C$. White and red ginseng powder were puffed inconsistently and discontinuously at $115^{\circ}C$. The scanning electron microphotograph of extruded white ginseng was uniform air cell distribution at 100oe, but pore size increased at $115^{\circ}C$ and had fine uniformity due to pore explosion. White ginseng and its extrudate were pseudoplastic. Intrinsic viscosity was lower as a result of increased die temperature. The cross-sectional expansion seems to be inconsistent and decreased due to decrease in melt viscosity at $115^{\circ}C$.

Determination of Elastic Recovery for Axi-Symmetric Forged Products (축대칭 단조공정에서 최종제품의 탄성회복에 관한 해석)

  • Kim, T.H.;Kim, D.J.;Park, J.C.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.9
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    • pp.165-173
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    • 1996
  • The dimensional accuracy of a final product is mainly affected by elastic die deformation during the forging and elastic recovery after the ejection in cold forging process. The investigations on elastic recovery are not so much as those of elastic die deformation. The elastic recovery can be determined by using the elastic-plalstic finite element analysis, but, this method has some limits such as poor conver- gence and long computational time, etc. In this paper, a theoretical analysis for predicting the elastic recovery of a final product in axi-symmetric forging process by using the rigid-plastic finite element method is presented. The rigid-plastic finite element analysis of a cold forward extrusion process involving loading, ejecting process is accomplished by rigid-plastic FE code, DEFORM. The effect of elastic die deformation on the final product dimenmsion is also considered. The calculated elastic recovery is compared is compared with the analysis result of elastic-plastic FE code. ABAQUS.

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Effects of mushroom composition on the quality characteristics of extruded meat analog (버섯 첨가가 압출성형 대체육의 품질 특성에 미치는 영향)

  • Cho, Sun Young;Ryu, Gi-Hyung
    • Korean Journal of Food Science and Technology
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    • v.52 no.4
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    • pp.357-362
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    • 2020
  • This study was conducted to investigate the effects of mushroom composition (0, 4, 8, and 12%) on the quality characteristics of an extruded meat analog. The meat analog blend was isolated soy protein, wheat gluten, and corn starch (50:40:10). The extrusion condition was set to 55% feed moisture, 170℃ barrel temperature, and 150 screw speed by high moisture extrusion using a twin-screw extruder equipped with a cooling die. The integrity index, hardness, cohesiveness, springiness, chewiness, and cutting strength of the meat analog increased with the increasing mushroom content, while its water holding capacity and nitrogen solubility index (NSI) decreased. The protein digestibility decreased with the increasing mushroom content, while the DPPH radical scavenging activity significantly increased. In conclusion, the incorporation of mushrooms into the investigated meat analog enhanced its texture and antioxidant level.

Development of polypropylene-clay nanocomposite with supercritical $CO_2$ assisted twin screw extrusion

  • Hwang, Tae-Yong;Lee, Sang-Myung;Ahn, Young-Joon;Lee, Jae-Wook
    • Korea-Australia Rheology Journal
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    • v.20 no.4
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    • pp.235-243
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    • 2008
  • The aim of this study is to explore the possibility of incorporating supercritical carbon dioxide ($scCO_2$) into twin screw extrusion process for the production of polypropylene-clay nanocomposite (PPCN). The $CO_2$ is used as a reversible plasticizer which is expected to rapidly transport polymeric chains into the galleries of clay layers in its supercritical condition inside the extruder barrel and to expand the gallery spacings in its sub-critical state upon emerging from die. The structure and properties of the resulting PPCNs are characterized using wide-angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), rheometry, thermogravimetry and mechanical testing. In the processing of the PPCNs with $scCO_2$, optimum $scCO_2$ concentration and screw speed which maximized the degree of intercalation of clay layers were observed. The WAXD result reveals that the PP/PP-g-MA/clay system treated with $scCO_2$ has more exfoliated structure than that without $scCO_2$ treatment, which is supported by TEM result. $scCO_2$ processing enhanced the thermal stability of PPCN hybrids. From the measurement of linear viscoelastic property, a solid-like behavior at low frequency was observed for the PPCNs with high concentration of PP-g-MA. The use of $scCO_2$ generally increased Young's modulus and tensile strength of PPCN hybrids.

A Study on the Creation of Porosity in Al Alloy(AA2014) Large Rod Preforms by Spray Forming (분무성형법에 의한 Al 합금(AA2014) 대형봉상성형체 제조시 기공발생에 관한 연구)

  • Shin, Don-Soo;Yoon, Eui-Park
    • Journal of Korea Foundry Society
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    • v.17 no.5
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    • pp.494-501
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    • 1997
  • In order to manufacture large rod preforms of 2014 Al alloy with a good mechanical property by spray forming method, it was spray-formed at a droplet temperature of $715^{\circ}C$, a droplet flight distance of 400mm, and a spraying angle of $35^{\circ}$. The rod preforms were extruded at $397^{\circ}C$ with the die temperature of $420^{\circ}C$ under the hot extrusion ratio 21:1 and T6 heat treatment was performed. The 2014 Al alloys cast by hot top process were also extruded and heat-treated at the same condition as a reference material. Microstructural observation and tensile test were carried out to investigate the effects of extrusion on microstructure and mechanical property of spray-formed Al alloy. Spray-formed Al alloys had many porosities due to inappropriate process conditions such as long droplet flight distance and low droplet temperature but have fine equiaxed grain. These porosities were reduced with decreasing in grain size by hot extrusion. Ultimate tensile strength and yield strength of spray formed-extruded 2014 Al alloy were inferior to those of the normal cast-extruded 2014 Al alloy, but elongations were superior. The control of porosity was important to get spray formed preform with a good mechanical property.

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Simulation of Coextrusion Process of Cladded Finned Tube by Plasticine (동시 압출법에 의한 핀형 튜브 Cladding 공정의 Plasticine 압출 모사)

  • Lee, Hyun-Woo;Park, Jin-Sung;Kim, Woo-Sik;Shin, Dong-Hyuk;Kim, Yong-Seog
    • Transactions of Materials Processing
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    • v.7 no.1
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    • pp.59-65
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    • 1998
  • In this study an attempt was made to simulate the coextrusion process of the cladded finned tube manufacturing by extrusion of plasticine. The effects of the billet and the plate inserted between the ingot and extrusion die on the variation of clad thickness of the extruded tube were studied. The results showed that cladded tube with uniform thickness can be obtained by a proper combination of clad thickness of billet and the plate. The relative strength of the billet and clad materials did not affect significantly on the variation of the clad thickness of the extruded tubes.

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A Study on Developementof UBST Program for Axisymmetric Metal Forming Process (축대칭 성형공정에 대한 유동함수 상계요소법의 프로그램 개발에 관한 연구)

  • 김영호;배원병;박재우;엄태준
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1995.03a
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    • pp.124-130
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    • 1995
  • An upper-bound elemental stream function technique(UBST) is proposed for solivng forging and backward extrusion problems that are geometrically complex or need a forming simulation . And in the forging problems, this study investigates that layer of elements effects dissipation of total energy and load. The element system of UBSTuses the curve fitting property of FEM and the fluid incompressiblity of the stream function . The foumulated optimal design problems with constraints ae solved by the flixible toerance method. In the closed-die forging and backward extrusion, the result of layer of element by this study produces a lower upper-bound solution than that fo UBET and conventional layer of element . And the main advantage of UBST program is that a computer code, once written , can be used for a large variety problems by simply changing the input data.

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