• 소성∙가공
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• 제14권5호
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• pp.444-451
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• 2005

A new extrusion process of the circular section product with helical fins could be developed by rotating extrusion die. The twisting of extruded product is caused by the twisted conical die surface connecting the die entrance section and the die exit section linearly. But, until now, because the process has used fixed extrusion die, it needs high pressure in order to twist billet and form fin shape on the surface of billet. So, during extruding billet, in order not to twist billet, the extrusion die is needed to rotate itself instead of twisting of billet. It is known that it is possible to reduce extrusion load of product with helical fins by analysis and experiments using rotating die. And it is known that, through the extrusion load analysis by $DEFORM^{TM}-3D$ software, optimal rotational velocity of rotating die can be obtained according to reduction ratio of area and twisted angle of die. And experiments and analysis using rotating extrusion die show that the twisted angle of product can be controlled by twisted angle of extrusion helical die and the rotational velocity of extrusion helical die.

• Advances in concrete construction
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• 제9권1호
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• pp.93-102
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• 2020

In this study, we examined the relationship among the rheological properties, workability, and extrudability in the construction of concrete structures using additive manufacturing. We altered the component materials (binder type, water-binder (W/B) ratio, sand ratio) to assess their effect on the rheological properties experimentally. The results indicated that the W/B and sand ratios had the largest effect on the rheological properties. In particular, when the sand ratio increased, it indicated that adjusting the sand ratio would facilitate control over the rheological properties. Additionally, we compared the rheological properties with the results of a traditional workability evaluation, namely the table flow test. This indicated the possibility of inferring the rheological properties by using traditional methods. Finally, we evaluated extrusion quantity according to table flow. The extrusion rate was 350 g/s for a flow of 210 mm and 170 g/s for a flow of 130 mm, indicating that extrusion rate increased as flow increased; however, we concluded that a flow standard of approximately 140-160 mm is suitable for controlling the actual extrusion quantity and rate.

• 반도체디스플레이기술학회지
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• 제15권2호
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• pp.81-86
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• 2016

Moisture vapor transmission rate (MVTR) is an important item for many applications of polymer breathable thin film. To determine the optimum values of the process parameters, it is essential to find their influence on The significance of six important process parameters namely, extruder cylinder temperature, extruder speed, extruder dies temperature, cooling roll temperature, stretching ratio, stretching roll temperature on breathable film strength of polymer extrusion was determined. Moreover, this paper presents the application of Taguchi method and analysis of variance (ANOVA) for maximization of the breathable film MVTR influenced by extrusion parameters. The optimum parameter combination of extrusion process was obtained by using the analysis of signal-to-noise ratio. The conclusion revealed that extruder speed and stretching ratio were the most influential factor on the film strength, respectively. The best results of film MVTR were obtained at higher extruder speed and stretching ratio.

• 한국식품과학회지
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• 제26권1호
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• pp.98-101
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• 1994

가수율을 변화시켜 취반한 밥의 관능검사, extrusion test, 수분함량측정 등의 실험을 통해 질지도 되지도 않은 보통의 밥상태를 만들기 위해 필요한 취반 가수율을 결정할 수 있었다. 밥의 압출력은 밥의 경도에 대한 관능 검사치와 정의 상관, 수분함량과는 부의 상관을 보였다. 관능 검사에서 질거나 되지 않은 보통밥상태로 평가된 밥의 수분함량은 62.3%, 압출력은 59.7kg이었으며, 이때의 가수율은 1.46배였다.

• 한국분말재료학회지
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• 제16권6호
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• pp.438-441
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• 2009

Mg-Cu composites were successively fabricated using a combination of rapid solidification and extrusion processes. In addition, the microstructural variation of the composite was investigated by performing the extrusion repeatedly. It resulted that the composite formed an uniform and dense structure by the extrusion, and the microstructure became fine as the extrusion conducted repeatedly. The microstructural variation was known to be dependent on the number of extrusion and the area reduction ratio. The tensile strength was also measured as a function of the microstructural variation.

• 한국미생물·생명공학회지
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• 제23권4호
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• pp.425-431
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• 1995

A kinetic model of the cyclodextrin formation in a heterogeneous enzyme reaction system using swollen extrusion starch as substrate was derived emphasing the structural features of extrusion starch. The degree of gelatinization, the ratio of accessible and inaccessible portion of extrusion starch, adsorption of CGTase on swollen starch, the structural transformation during reaction, and product inhibition caused by produced CDs were considered in deriving kinetic model. Various kinetic constants were also evaluated. The derived kinetic equation was numerically simulated, which result showed that the derived kinetic equations can be used to predict the experimental data reasonably well under the various experimental conditions. Kinetic model can be utilized for the optimization of enzyme reactor and the process development for CD production from swollen extrusion starch.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.74-77
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• 2000

Porthole die extrusion has a great advantage in the forming of hollow section tubes difficult to produce by conventional extrusion with a mandrel on the stem. Because of the complicated structure of die assembly, extrusion process as a forming of hollow section tubes has been investigated experimentally Therefore, analytic approaches that are useful in profitable die design and in the improvement of productivity are inevitably demanded Welding strength is affected by many parameters, which are such as extrusion ratio, extrusion speed, die shape, porthole number, bearing length, billet temperature and mandrel shape. In this paper, the parameters, which are such as billet temperature, bearing length and tube thickness, are examined. The welding pressures are examined through 3D simulation of non steady state and compared with experimental results.

• 소성∙가공
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• 제18권1호
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• pp.80-86
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• 2009

This paper presents the plastic inhomogeneous deformation behavior of bimetal composite rods during the axisymmetric and steady-state extrusion process through a conical die. The rigid-plastic FE model considering frictional contact problem was used to analyze the co-extrusion process with material combinations of Cu/Al. Different cases of initial geometry shape for composite material were simulated under different conditions of co-extrusion process, which includes the interference and frictional conditions. From the simulation results, the sleeve cladding rate at the core/sleeve interface was recorded as a distribution of diameter ratio and interference conditions, which will be useful for the investigations of the bonding process during co-extrusion process. In addition, the results of the co-extrusion, connected with the results of the variations of diameter rate and average contact pressure, demonstrate a good agreement and present the possibility of describing the parameters of the plastic zones in non-uniform deformation of these type of composite materials.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.718-719
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• 2006

Two different commercial aluminium powder grades have been densified by direct hot extrusion. The extrusion temperature was $425^{\circ}C$, with an extrusion ratio of 1:16. Prior to extrusion, some green compacts were pre-sintered ($500^{\circ}C$). The evolution of the extrusion load during the process and the hardness of the final products have been investigated. Additionally, microstructural characterization by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Backscattered Diffraction (EBSD) was carried out. The obtained results evidence grain refinement. Additionally, inter-metallic precipitation, dynamic recovery and geometric dynamic recrystallization take place depending on some process variables, powder composition, heat treatment, strain $\ldots$

• 소성∙가공
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• 제16권5호통권95호
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• pp.386-390
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• 2007

In order to, simultaneously, synthesize and control the size of microstructure of amorphous/crystalline composites, a repeated extrusion process was performed using the gas atomized $Cu_{54}Ni_6Zr_{22}Ti_{18}$ metallic glass powders and the crystalline brasses. The size of microstructure in the resultant composites was varied depending on the pass of extrusion as well as on the area reduction ratio. The microstructure could be estimated using an equation of $r_n=r_{n-1}/R^{1/2}$, where R is reduction ratio and $r_n$ is the resultant radius of the extruded bar after n pass. Theory of microstructural refinement as well as the relationship between the resultant microstructures and mechanical properties was discussed.