• Transactions of Materials Processing
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• v.9 no.6
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• pp.567-573
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• 2000

An analysis system for evaluating the design of dieface of stamping press dies is developed. The die design analysis system interfaced with CATIA via universal or NASTRAN data format provides the design information such as binder-wrap, punch contact status, section length change ratio, wrinkle symptom etc., which are crucial in predicting the defects of initial shape of the sheet in the dieface design stage. The graphic post-processor of developed system which displays 3-dimensional shapes of tool and die and analysis results, helps the interpretation of design evaluation. The dieface design analysis system was tested in draw dies of front floor panel and quarter panel of auto-body in order to verify the usefulness and validity of the system The examples show that the developed system would be a good tool in evaluating dieface designs.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.4
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• pp.79-85
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• 2006

Multi-filament hydrostatic extrusion was developed as a fine wire manufacturing process and wire forming experiments were conducted. Also, single wire stretch forming process was proposed in the possibility of obtaining long wire with constant cross-section. In the multi filament extrusion since the workpiece, die and forming facility are in the macro forming circumstance, fine wire and fine hole structure with less than a few micrometer can be easily obtained. Although stretch forming does not use a die in order to avoid the friction problem between the workpiece and the die, it is necessary to have high level of technology to maintain cross-sectional shape and measure in longitudinal direction.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.493-503
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• 1998

The sectional forming analysis considering bending effects from the geometrically deformed shape of two linear membrane finite elements(called super element) was performed under plane strain assumption for analyzing forming processes of an arbitrarily shaped draw-die. For the evaluation of bending effects, the bending equivalent forces are calculated from the bending moment computed using the changes in the interior angle at the middle node of super element, and are agumented to the membrane stretch forces. In order to verify the validity of the bending formulation, the simulation results for the stretch, draw, and bend sections were compared with membrane analysis results and measurements.

• Journal of Ocean Engineering and Technology
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• v.15 no.2
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• pp.66-71
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• 2001

A sectional analysis of trunk-lid carried out by using the equilibrium approach based on the force balance together with geometric relations and plasticity theory. In computing a force balance equation, it is required to define a geometric curve approximating the shape of sheet metal at any step of deformation from the interaction between the die and the deformed sheet. The trunk-lid panel material is assumed to possess normal anisotropy and to obey Hill's new yield criterion. Deformation of each section of trunk-lid panel is simulated and composed to get the three-dimensional shape by using CAD technique. It was shown that the three-dimensional shape composition of the two-dimensional analysis.

• Design & Manufacturing
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• v.13 no.4
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• pp.17-22
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• 2019

Currently, studies on weight reduction and fuel efficiency increase are the most important topics in the automotive industry and many studies are under way. Among them, weight reduction is the best way to raise fuel efficiency and solve environmental pollution and resource depletion. Materials such as aluminum, magnesium and carbon curing materials can be found in lightweight materials. Among these, research on improvement of bonding technology and manufacturing method of materials and improvement of material properties through study of ultrahigh strength steel sheet is expected to be the biggest part of material weight reduction. As the strength of the ultra hight strength steel sheet increases during forming, it is difficult to obtain the dimensional accuracy as the elastic restoring force increases compared to the hardness or high strength steel sheet. It is known that the spring back phenomenon is affected by various factors depending on the raw material and processing process. We have conducted analytical evaluations and studies to analyze the springback that occurs according to the cross-sectional shape of the ultra high tensile steel sheet.

• Transactions of Materials Processing
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• v.1 no.1
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• pp.66-74
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• 1992

According to the variation of hydrostatic pressure on the central axis of deformable material, the V-shaped central bursting defect may be created in extrusion or drawing processes. The process factors which affect the generation of defects are semi-angle of die, reduction ratio of cross-sectional area, friction factor, material properties and so on. The combination of these factors can determine the possibility of defect creation and the shape of various round holes which have been created inside already. By the rigid plastic finite element method, this paper describes the observations of change in shape of round holes with process conditions such as semi-angle of die, reduction ratio of cross-sectional area and friction factor at the non-steady state of axisymmetrical extrusion process when the round hole is already existed inside the original billet. Also, the effects of process factors are investigated to prevent the possible defects.

• Fibers and Polymers
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• v.1 no.1
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• pp.37-44
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• 2000

A finite element method is employed fer a flow analysis of the melt spinning process of a non-circular fiber, a PET(polyethylene terephthalate) filament. The flow field is divided into two regions of die channel and spin-line. A two dimensional analysis is used for the flow within the die channel and a three dimensional analysis fur the flow along the spin-line. The Newtonian fluid is assumed for the PET melt and material properties are considered to be constant except for the viscosity. Effects of gravitation, air drag force, and surface tension are neglected. Although the spin-line length is 4.5 m only five millimeters from the spinneret are evaluated as the domain of the analysis. Isothermal and non-isothermal cases are studied fer the flow within the die channel. The relationship between the mass flow rate and the pressure gradient is presented for the two cases. Three dimensional flow along the spin-line is obtained by assuming isothermal conditions. It is shown that changes in velocity and cross-sectional shape occur mostly in the region of 1mm from the die exit.

• Design & Manufacturing
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• v.16 no.2
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• pp.53-59
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• 2022

Unlike other press forming processes, ISF (Incremental sheet forming) doesn't require a punch and die set. However, during the ISF processes unwanted bending deformation occurred around the target geometry. This paper is aimed to analyze the effect of the die structure, which is supported by bolts, on the geometric accuracy of the ISF processes. In this research, the ISF processes with Al5052 sheet of 0.5 mm, the tool diameter of 6 mm and the stepdown of 0.4 mm was employed. L-shaped, step-shaped, relief-shaped geometry were employed in experiments. Sectional view and the plastic strain were compared. From this research we find out that the bolt supported ISF processes increases the geometric accuracy of products very effectively.

• Design & Manufacturing
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• v.13 no.1
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• pp.61-67
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• 2019

The cooling unit of the industrial showcase consists of a compressor, a condenser and an evaporator. An axial fan is used to circulate the air to improve the efficiency of the heat exchanger. In the past, aluminum fans have been used, which have problems such as low performance, efficiency, high failure rate, and high noise. This study is to develop high performance, high efficiency plastic fan replacing aluminum fan. A major factor in determining the performance and noise of an axial fan is the angle and cross-sectional shape of the blade, which is suitable for raising the lift force, thereby controlling the vortex, which is the main cause of noise and performance degradation. In order to produce a high efficiency injection molded fan, it is necessary to develop a mold that minimizes the deformation of the injection process for the designed shape. In this study, we developed a high efficiency, low noise plastic injection fan with more than 11% performance improvement and noise reduction compared to conventional aluminum fan.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1992.03a
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• pp.27-46
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• 1992

In this study a new simplified three-dimensional numerical method and the associated computer program have been developed to simulate the non-axisymmetric extrusion processes. The two-dimensional rigid-plastic finite element method under the generalized plane-strain condition, is combined with the slab method. To define the die geometry for non-axisymmetric extrusion, area mapping technique was used. Streamlined die surface was used to miniminze the total extrusion pressure. Extrusion of square, hexagonal and "T" section from round billet have been simulated and experimented with a model material. The computed results were in good agreement with the experiments in cross-sectional grid distortion. Computational results will be valuable for designing tool geometries and corresponding processes.