• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.379-381
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• 2009

In designing full vehicle, crash safety, fuel efficiency, exhaust gas, and driving stability are very important factors. Especially, automotive wheel which supports total vehicle weight is a critical component in view of driving stability. Most of automotive wheel have been manufactured for beautiful appearance by using aluminum alloy in domestic industry. However, the amount of automotive steel wheel used are on an increasing trend according to developing the advanced high strength steel with good formability property recently. In this study, the circumferential deviation of rim with various thickness and yield strength was investigated. The formability evaluation of the rim was developed by using a finite element module furnished by Forge software.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.225-228
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• 2003

This paper is concerned with pressure welding, which has been known as a main bonding mechanism for the cold and warm clad forming. Bonding characteristics of pressure welding between the copper and aluminum plates are experimentally investigated. Experiments are performed at the cold and warm temperature range with the variation of important factors such as magnitude of pressure, surface roughness of Cu and Al plates, and pressure holding time. It could be concluded that the bonding criterion might be given as a function of bonding pressure and surface roughness for the cold and warm temperature ranges.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.232-235
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• 1995

A side-extrusion model, meant for deeper understanding of the material flow in the CONFORM (continuous extrusion forming) of trub shaped aluminum profiles is presented. In order to get the desirded straight shape of the extrudate,every part of its cross-section must exit the die with the same velocity. Problem is assumed by plane strain UBET-model to analyze it in a simplified way. This has been done by studying the side-extrusion through a two -hole die face. The flow is balanced by determining the optimum lengths of the bearing lands, i.e., those lengths which result in equal exit velocities of the extrudates. Furthermore, the material flow, as influenced by the punch velocity, has been investigated.

• Transactions of Materials Processing
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• v.6 no.5
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• pp.425-434
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• 1997

A superplastic material, aluminum-lithium alloy 8090, was examined with uniaxial tensile tests to investigate its thermomechanical behavior. The tests were carried out at the strain rate ranging from $2X10^4 to 1X10^2$ and at the temperature from 48$0^{\circ}C$ to 54$0^{\circ}C$. The experiments produced force-dis-placement curves which were converted to stress-strain curves. From the curves, the optimum conditions of superplastic forming were obtained by deteriming the strain rate sensitivety, the optimum strain rate, and the strength coefficient for various forming temperatures.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.902-905
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• 2000

As the manufacturing processes of automotive engine piston, gravity die-casting, squeeze casting, hot forging and powder forging process are generally used for the various specifications. As the semi-solid forming(SSF) is compared with conventional casting such as gravity die-casting and squeeze casting for the characteristics of its process, the product without inner defects such as gas porosity and segregation can be obtained and its microstructure is globular grain. In SSF process, the materials are heated up to the temperature between the solvus and liquidus line at which the materials exists in the form of liquid-solid mixture. In this time, Discussion is given about reheating process of row material and results are presented regarding accurate temperature and process variables controlling for right solid fractions.

• Transactions of Materials Processing
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• v.16 no.6
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• pp.443-446
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• 2007

The semi-solid process has been developed near net-shape components for kinds of methods. Thixo-forming with reheating prepared billet and rheo-forming with cooled melt until semi-solid state. Material is applied electromagnetic stirring system to slurry with aluminum 6061 alloy. An experiment has variation factors which are pressure, solid-fraction, stirring current and stirring time. The mechanical properties are compared to forge sample with to apply heat treatment T6. This study is researched function a virtual pressure and fine shape zone. Optimum pressure is found to prevent defect of porosity.

• Transactions of Materials Processing
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• v.25 no.1
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• pp.5-11
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• 2016

The control of the roll velocities is essential in maintaining stability during ring rolling, but such control is difficult. The determination of the best roll velocities can be helped with the use of FE simulations and processing maps, which give the useful information such as power dissipation and flow instability for hot metal forming processes. In the current study, the workability of 7050 aluminum alloy is evaluated by using processing map. With the developed information, the stability of the ring rolling condition, called the Constant Growth Velocity Condition (CGVC), is evaluated.

• Journal of the Korean Ceramic Society
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• v.23 no.6
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• pp.71-75
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• 1986

The forming reaction processes of magnesium aluminate spinel by a thermal decomposition of sulfate hydrate were studied with DTA, TG. SEM and X-ray powder diffraction methods. The hydrous salt composed of the mixture of the two compounds of $MgSO_4$ $6H_2O$ and ${AL_2}({SO_4})_17H_2O_3$ in which both sulfates were crystalline. On heating the hydrous slat the crystalline magnesium and aluminum sulfate anhydride to amorphous alumina magnesium sulfate anhydride decomposed to amorphous magnesia and these amorphous oxides reacted completely each other to form a spinel at $1000^{\circ}C$ The apparent activation energy of forming reaction of spinel was 36.5 kcal/mole($900^{\circ}C$~$1000^{\circ}C$) The crystallite size of spinel obtained at $1000^{\circ}C$ after 1 h was 380$\AA$.

• Journal of Power System Engineering
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• v.3 no.2
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• pp.89-97
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• 1999

In this paper the forming simulations of ellipse bulge have been researched by using $PAM-STAMP_{TM}$ to estimate the sheet metal forming and the plastic deformation characteristic of ellipse bulge. Thin elliptical diaphragms of brass, copper, aluminum, and mild steel are bulged in elliptical dies having aspect ratios of 1.33 and 2. In order to compare the simulation results with the experiment and ellipse bulge's theory derived by using Johnson and Duncan's theory, the relations of hydraulic pressure and polar height, polar thickness strain and polar height, were compared. According to this study, the results of simulation and ellipse bulge's theory derived by using Johnson and Duncan's theory, and the bursting pressure and the bursting polar height are good agreement to the experiment. So, the results of simulation by using $PAM-STAMP_{TM}$ and the ellipse bulge's theory will give engineers good information to make assessment the formability and plastic deformation characteristic of hydraulic ellipse bulge test.

• Transactions of Materials Processing
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• v.12 no.8
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• pp.693-701
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• 2003

In this paper, the influence of frictional conditions on the backward impact extrusion of aluminum battery casing with large aspect ratio has been investigated. In the simulation, MSC.Superforge, a package based on the finite volume method, is used for the extrusion analysis. The formability and earing problem during the production have been evaluated by studying the sensitivity to frictional effects. During the sensitivity analysis, the friction factor was varied from 0.02 to 0.24. As the friction factor is increased, the forming height of the narrow edge is decreased, and the forming height of the wide edge is increased. When the friction factor becomes 0.2, the earing problem does not occur The experimental results show a good agreement with analytical results.