• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1996.10a
• /
• pp.185-191
• /
• 1996

The Variation of die bearing is primary way to control the metal flow in hot square die extrusion process. Finite element computations are carried out to assess the influence of die bearing on metal flow and state variables. The finit element method is developed based on ALE description for a rigid-viscoplastic material. Since thermal state computational example, hot square die extrusion with varied die bearing lengths has been analyzed for the profile of a L-section.

• Transactions of Materials Processing
• /
• v.14 no.4 s.76
• /
• pp.351-359
• /
• 2005

The semi-solid processing is now becoming of great interest for the production of various parts by pressure die casting. Also, the rheo-casting has been substituted for thixo-casting, because the rheo-casting can control the solid particles to globular and non-dendritic solid phase. In the rheo-casting process, the important thing is to control the solid particles behavior in semi-solid materials. So in this paper, to control solid particles behavior in semi-solid materials, we experimented about the die filling tests during the semi-solid die casting in 0.3, 0.4, 0.5 and 0, 6 solid fraction. The die filling in semi-solid die casting were simulated by MAGMA soft/thixo module. By the die filling tests and computer simulation, the effect of solid particles behavior in rheology flow had been investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.664-667
• /
• 2004

The semi-solid processing is now becoming of great interest for the production of various parts by pressure die casting. Also, the rheolory casting has been substituted for thixo casting, because the rheology casting can control the solid particles to globular and non-dendritic solid phase. In the rheology casting process, the important thing is to control the solid particles behavior in semi-solid materials. So in this paper, to control solid particles behavior in semi-solid materials, we experimented about the die filling during the semi-solid die casting in 0.3, 0.4, 0.5, 0,6 solid fraction. The die filling in semi-solid die casting were simulated by MAGMAsoft/thixo module. By the die filling tests and computer simulation, the effect of solid particles behavior in rheology flow had been investigated.

• The Journal of Korean Academy of Prosthodontics
• /
• v.37 no.3
• /
• pp.383-394
• /
• 1999

The indirect technique for making cast restoration requires that dies be as accurate and durable as possible. Currently, stone is the most commonly used material for die. However, it has some problems such as the weakness in its strength and low abrasion resistance. Recently, epoxy resin die systems have become available. The purpose of this study was to examine two commercially available resin die systems and evaluate some characteristics for their clinical performance. This study evaluated the dimensional accuracy of epoxy resins and their wettability with impression materials. In this study, the first experiment was about dimensional accuracy of different die materials. The master model was made of stainless steel. 10 models were made of two epoxy resins (Die-epoxy, Tri-epoxy) and a die stone (Fujirock) each. Occlusal diameter (Dimension I), occluso-gingival height (Dimension II), and interabutment distance (Dimension III) were measured in each model. Next, the contact angles of die materials with impression materials were observed. The blocks were made of polyether, hydrophilic additional silicone, polysulfide impression materials. By drop-ping the same amount (0.05ml) of Tri-epoxy, Die-epoxy, and die stone on the blocks, 10 samples of each die material were made. After setting of materials, the contact angles were measured. The results of this study were as follows. 1. The expansion of stone die and the shrinkage of resin dies in occlusal diameter were observed, and stone and Tri-epoxy were expanded and Die-epoxy was shrinked in occluso-gingival height. There was little change among materials in interabutment distance (p<0.05). 2. In comparison with the master model Tri-epoxy had the least variation in measurement of the three die systems examined. Die-epoxy was next, and die stone showed the greatest variation. 3. The compatibility of die stone for polyether, hydrophilic additional silicone, polysulfide decreased in order, wherease epoxy materials had the decreased compatibility for polyether and polysulnde, hydrophilic additional silicone in order. It was not statistically different between polyether and polysulfide (p<0.05). 4. The contact angles of Tri-epoxy, Die-epoxy, die stone were getting bigger in order.

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

• Koreanishche Zeitschrift fur Deutsche Sprachwissenschaft
• /
• v.10
• /
• pp.201-229
• /
• 2004

In der vorliegenden Albeit wird die funktionale $Dom\"{a}ne$ der Konkomitanz unter funktional-typologischen Gesichtpunkten untersucht. Dabei wird ein funktionales Rahmenwerk fur die Untersuchungen $\"{u}ber$ die verschiedenen komitativen und intrumentalen Relationen entwickelt. Es gibt eine Reihe von Partizipantenrelationen in der funktionalen $Dom\"{a}ne$ der Konkomitanz, $\n\"{a}mlich$ 'Partner', 'Companion', 'Vehicle', 'Tool', 'Material' und 'Manner'. Diese Partizipanten $k\"{o}nnen$ als Konkomitant bezichnet werden. Sie bilden ein Kontinuum $bez\"{u}glich$ der Empathiehierarchie sowie der Kontrollhierarchie. Konkomitanten $k\"{o}nnen$ bei ihrer syntaktischen Kodierung $gem\"{\a}{\ss}$ den spezifischen Typen der konkomitanten Relationen und ihren absoluten Eigenschaften variieren. Es werden sieben verschiedene Typen der Kodierungsstrategien vorgestellt, d.h. konkomitante $Pr\'{a}dikation$, adpositionale Markierung, Kasusmarkierung, Verbderivation, inkorporation, Konversion und lexikale Fusion. In einer gegebenen Sprache kann es $nat\"{u}rlich$ feinere Variation, die z.B. mit den Graden der Grammatikalisierung und Lexikakisierung dieser Kodierungsstrategien zu tun hat, geben. Die Distribution der strukturellen Apparaturen auf der funktionalen $Dom\"{a}ne$ der Konkomitanz ist innerhalb einer Sprache nicht einheitlich. Dies gilt auch $f\"{u}r$ den Sprachen (z.B. Deutsch und Englisch), die gewohnlich als ein typisches Beispiel fur den Synkretismus zwischen Komitativ und Instrumental angesehen werden. Die $Pr\"{a}position$ mit im Deutschen $dr\"{u}ckt$ nur eine Teilmenge der verschiedenen konkomitanten Relationen aus. Tlansportrnittei' und Material' werden also nicht durch die $Pr\"{a}position$ mit $ausgedr\"{u}ckt$. Beim Ausdruck der konkomitanten Relationen verwendet Deutsch konsistent die Strategie der adpositionalen Markierung. Andere $m\"{o}gliche$ Strategien $k\"{o}nnen$ als ein minimaler Sonderfall angesehen werden. Koreanisch $verf\"{u}gt$ hingegen auf zwei Ausdrucksstrategien, $n\"{a}mlich$ konkomitante $Pr\"{a}dikation$ und Kasusmarkieriing. Die Auswahl zwischen den beiden Strategien ist meistens von den Empathieeigenschaften der Konkomitanten $abh\"{a}ngig$. Auch innerhalb einer Ausdrucksstrategie spielt die Empathie der Konkomitanten eine wichtige Rolle bei der Auswahl der Strukturmittel. Einen Synkretismus weisen im Koreanischen 'Partner' & 'Companion' einerseits und 'Vehicle' & 'Tool' & 'Material' andererseits auf, Die Ersteren werden durch die auditive Kasusmarkierung und die Letzteren durch die instrumentale Kasusmarkierung ausgedruckt. Ein Synkretimus beim Ausdruck der verschiedenen konkomitanten Relationen ist in den Sprachen, die nur konkomitante $Pr\"{a}dikation$ aufweisen, nicht zu erwarten, denn ein konkomitantes $Pr\"{a}dikat$ gibt die Art der Beteiligung der Konkomitanten an der Situation lexikalisch mehr oder weniger explizit wieder

• Design & Manufacturing
• /
• v.17 no.3
• /
• pp.15-20
• /
• 2023

In the fine blanking process, which is a press operation known for producing parts with narrow clearances and high precision through the application of high pressure, die roll often occurs during the shearing process when the punch penetrates the material. This die roll phenomenon can significantly reduce the functional surface of the parts, leading to decreased product performance, strength, and fatigue life. In this research, we conducted an in-depth analysis of the factors influencing die roll in the curvature area of the fine blanking process and identified its root causes. Subsequently, we designed and experimentally verified a die roll reduction process specifically tailored for the door latch manufacturing process. Our findings indicate that die roll tends to increase as the curvature radius decreases, primarily due to the heightened bending moment resulting from reduced shape width-length. Additionally, die roll is triggered by the absorption of initial punch energy by scrap material during the early shearing phase, resulting in lower speed compared to the product area. To mitigate the occurrence of die roll, we strategically selected the Shaving process and carefully determined the shaving direction and clearance area length. Our experiments demonstrated a promising trend of up to 75% reduction in die roll when applying the Shaving process in the opposite direction of pre-cutting, with the minimum die roll observed at a clearance area length of 0.2 mm. Furthermore, we successfully implemented this approach in the production of door latch products, confirming a significant reduction in die roll. This research contributes valuable insights and practical solutions for addressing die roll issues in fine blanking processes.

• Transactions of Materials Processing
• /
• v.10 no.3
• /
• pp.214-222
• /
• 2001

The homogeneous distribution of solid region without liquid segregation is important in terms of high quality component during thixoforming process. In closed die semi-solid forging process, liquid segregation is strongly affected by injection velocity than solid fraction because the material has to travel relatively long distance to fill the cavity through a narrow gate. The designed die by computer simulation data was used to thixoforging process. The thixoforming velocity to prediction the liquid segregation had been determined with strain rate associated with multistage velocity control during compression test of semi-solid material. The optimal forging velocity and die temperature were investigated to produce the near-net-shape compressor component. The mechanical properties of thixoformed component were tested with various die and material temperatures before and after heat treatment.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1513-1516
• /
• 2003

A crank throw, which is one of the crankshaft part for a large diesel engine is manufactured by closed die forging or open die forging. For the purpose of improvement of productivity the open die forging is usually adopted these days. However it has disadvantage of low yield ratio compare to closed die forging. To overcome this problem, the material properties for hot top and bottom zones of ingot are investigated to utilize them to the product and a modified forging process to reduce the material loss of ingot body through forging analysis according to forging factors(a , R, Ø$\sub$B/, Ø$\sub$D/) is suggested.

• Design & Manufacturing
• /
• v.2 no.2
• /
• pp.43-47
• /
• 2008

This paper is concerned with the analysis of material flow characteristics of stepped rod forming. The analysis in this paper concentrated on the evaluation of the design parameters for deformation patterns of tube forming, load characteristics, extruded length, and die pressure. The design factors such as punch nose radius, die corner radius, friction factor, and punch face angle are involved in the simulation. The stepped rod forming is analyzed by using a commercial finite element code. This simulation makes use of stepped rod material and punch geometry on the basis of punch geometry recommended by International Cold Forging Group. As radius ratio is large, forming load was reduced but extruded length ratio was increased.