• Design & Manufacturing
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• v.10 no.2
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• pp.24-28
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• 2016

In this study, relevant to impact extrusion process of the rectangular batter case for electric vehicles, numerical and experimental analyses were conducted to reduce the earring defects induced in the unevenness of metal flow. Since the earring is caused by the non-uniform metal flow induced in the friction and aspect ratio in the bottom section. As a way to reduce the earring, variable land die concept was applied. In order to analyze numerically the complex metal flow by using commercial finite element package, DEFORM 3D, impact extrusion process was simplified in upsetting mode at bottom section and extrusion mode at land section. The impact extrusion experiments were conducted to verify the assessment of process parameter for impact extrusion. As results, variable land die which has longer longitudinal section makes reduce earring defects. In addition, it was confirmed that the effect that slug shape like dog-bone also can reduce the earring. This study is expected to be able to present the useful design guidelines for manufacturing the battery case.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.63-66
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• 2000

This study presents development of an software for process and die design of hot extrusion through square dies. The design of extrusion dies is still an art rather than a science with increasing complexity of shape and thinness of section. Therefore most of the die design is still dependent on personal judgement intuition and experience. The objective of this study is to develop an software system which includes a design rule extracted from literatures and experts in the extrusion industry. The developed system is effectively used to design extrusion processes and dies with reduced lead time and trial extrusion.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.12
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• pp.136-141
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• 1996

In this paper, the design variables of the extruded parts involving flat die through model experiment are investigated to overcome some current problems such as bending and twisting and get more improved quality products. Above all, the deformation behavior is analyzed in experiment and investigated flow charactristics inside container. Finally, the straight extruded product is obtained by modified bearing land width on the basis of the exit velocities distribution from bended and twisted products.

• Transactions of Materials Processing
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• v.9 no.5
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• pp.486-493
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• 2000

Extrusion die-lip buildup has direct and negative impact on the properties of the final product. At the present time there is no absolute method of die-lip prevention. However, a Periodical shut down of extrusion line for the removal has been the general practice throughout the industry in concern. In this study the die-lip buildup was Investigated with a particular attention paid to the influence of die exit geometry and dimensions on the stresses produced at the point of die exit. To demonstrate the relationship between the stress state and the magnitude of the die-lip buildup, a method of virtual manufacturing was performed, assuming elastic-plastic material behavior for the high-density polyethylene under investigation. The overall numerical results suggested that the longer the die-land and/or the smaller the areal reduction of the die would reduce the tendency for the die-lip formation. Similarly, haying a fillet around the circumferential edge of the die exit would be favorable in decreasing the die-lip buildup.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.49-52
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• 1997

The kinematically admissible velocity field is developed for the analysis of the curving of an eccentric extrusion. The curving of product in extrusion is caused by the difference of the linearly distributed longitudinal velocity on the cross-section of the workpiece at the dies exit. The result of the analysis show that the curvature of product increases with the increase in eccentricity of gravity center of the cross-section of the workpiece at the die entrance from that of the cross-section at the die exit. It also increase with the die land dimension. By the DEFORMTM-3D analysis, the curving of T-shaped product in extrusion is changed by the eccentricity, die land length and the friction constant. The result of the analysis by DEFORMTM-3D software shows that the curvature of circular shaped product increases with the eccentricity. The two analysis and one experiment show the curving phenomenon in eccentric extrusion process.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.39-44
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• 2022

Using a CFD (computational fluid dynamics) simulation tool, we have offered a design guideline of a slot-die head having a simple T-shaped cavity through an analysis of the fluid dynamics in terms of cavity pressure and outlet velocity, which affect the uniformity of coated thin films. We have visualized the fluid flow with a transparent slot-die head where poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) is injected. We have shown that the fluid dynamics inside the slot-die head depends sensitively on the cavity depth, cavity length, land length, and channel gap (i.e., shim thickness). Of those, the channel gap is the most critical parameter that determines the uniformity of the pressure and velocity distributions. A pressure drop inside the cavity is shown to be reduced with decreasing shim thickness. To quantify it, we have also calculated the coefficient of variation (CV). In accordance with Hagen-Poiseuille's laws and electron-hydraulic analogy, the CV value is decreased with increasing cavity depth, cavity length, and land length.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.550-553
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• 2006

This study used the 3D CAD/CAM system in manufacturing die plates to improve productivity. UG NX 3.0 was used as 3D CAD/CAM software, with the created NC code transmitted to the CNC Milling and Wire Cut Electric Discharge machine. The die plate was then automatically machined.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.59-62
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• 2003

The precision cold forging of helical gear for steering pinion has been studied. Because of the large helix angle, there are many difficult problems to control the material flow and part dimension. The die shape was proposed to improve the flow of workpiece. In order to improve the dimensional accuracy of forged part, a FE analysis was performed. The proposed die shape drives to flow amicably workpiece. The applied load was reduced up to 10 percent, compared to the conventional-shaped-die. The elastic deformation of die has been investigated quantitatively by the 3-dimensional FE analysis. The die-land has been expanded up to $10{\mu}m$ on loading stage, based on the FEM results. Therefore, the elastic deformation amounts should be taken into consideration to improve the dimensional accuracy of forged helical gear.

• Koreanishche Zeitschrift fur Deutsche Sprachwissenschaft
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• v.5
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• pp.375-398
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• 2002

Um von der 'kritischen' Situation des Faches DaF rauszukommen, werden viele Versuche untemommen, durch die Verbesserung des Untenichts in der Richtung nach der Entwicklung der kommunikativen $F\"{a}higkeit$ Deutsch als Fremdsprache wieder attraktiv und $konkurrenzf\"{a}hig$ zu machen. Aber leider sieht die Zwischenbilanz nicht so erfolgreich aus. Eine der Ursachen $daf\"{u}r\;l\"{a}sst$ sich mE. darin sehen, dass die $Ans\"{a}tze,\;die\;haupts\"{a}chlich\;f\"{u}r$ den Unterricht von Deutsch als Zweitsprache entwickelt wurden, ohne $gen\"{u}gende$ Berucksichtigung auf die kulturellen und institutionellen Unterschiede zwischen den Lemsituationen im zielsprachigen Land und im Heimatland der Schuler eingesetzt werden. In diesem Kontext $w\"{a}re\;es\;n\"{o}tig$, auf die Unterschiede zwischen DaF und DaZ und ihre Wirkung auf die Lehrstrategien im DaF-Unterricht zuruckzugreifen, Dabei sind auf einige Faktoren besonders zu achten, die DaF-Untenicht vom DaZ-Untenicht unterscheiden: die Mangel an den $M\"{o}glichkeiten$ der authentischen Kommunikation, die $Homogenit\"{a}t\;der\;Sch\"{u}ler$, die Lemkultur in der schlulischen Institution, das Alter, in dem die Sch\"{u}ler$ mit dem Lemen der Zielsprache beginnen. Daraus lassen sich die folgenden unterrichtlichen Konsequenzen ergeben: Die Lehrer sollten sich bemtihen, den $Sch\"{u}lern\;die\;M\"{o}glichkeiten\;f\"{u}r$ die authentischen Kommunikation besorgen, besonders $au{\ss}erhaib$ des Unterrichts, z.B. durch das Chatting- Projekt, $w\"{a}hrend$ im Unterricht mehr $Anl\"{a}sse\;f\"{u}r$ die Reflexion gegeben sollten. Und dabei sollten die unterrichtlichen Vorteile-die gemeinsame Muttersprache und Kultur, das Alter usw. - aktiv benutzt werden. Die meisten Koreaner beginnen $n\"{a}mlich$ mit dem Lernen der zweiten Fremdsprache erst in oder nach der $Pubert\"{a}t$. In diesem Zusammenhang sollte es auch betont werden, dass sich die Autonomie der Lerner durch den Unterricht richtig entwickelt, damit sie $sp\"{a}ter$ ihre Fertigkeiten autonom entwickeln $k\"{o}nnen$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.98-101
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• 2001

In the present study, several design parameters of the flat-die extrusion process are investigated using the rigid-plastic finite element method. The effect of loaction of extrusion profile, arrangement of multiple extrusion profiles, and design of various die land has been investigated through the analysis. Several numerical examples of flat-die extrusion, such as C-section, multiple U- shape, and window guide extrusion, are analyzed. From the comparative study, the effect of design parameters is investigated. In each example, comparing the velocity distribution with that of the original design, it has been shown that the design modification affords much more uniform distribution of axial velocity