• Transactions of Materials Processing
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• v.13 no.1
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• pp.78-83
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• 2004

High-temperature superconduction materials(Bi2223) possess electrical/electronic and magnetic properties. Because high-temperature superconduction materials is a ceramic powder, that cannot be produced singlehandedly. So Ag sheathed Bi-2223 wire was produced by drawing process using powder-in-tube(PIT) method. This superconductor has many difficulties to produce. The main difficulty is that the mechanical properties of the ceramic powder are very different from those of the Ag sheath. And by these properties, Bi2223 high-temperature superconductor, which has a single filament drawing process and multi-filament drawing process, has a defect like sausaging and bursting at a center. This study analyzed multi-filament drawing process by FEM, and a defect generated during multi-filament drawing was studied by FEH. Specially, in order to prevent a bursting at a center, this study presented a method that inserts a pure Ag at a center of multi-filament wire

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.205-209
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• 1998

Unlike the drawing of round section from round bar, the shaped drawing like polygonal section is known to have influence not only drawing stress but also comer filling. Therefore, this study analyze the drawing process of suqare rod from round bar using nonsteady state rigid-plastic FEM. To investigate effects of process variables of the drawing process of square rod from round bar, FE-simulations with variety of reduction in area and semi-die angle for a given frictional condition have been conduction. By this results, it has to suggest optimal process condition on the drawing stress and the comer filling. In addition, it has determined forming limit considering necking and bulging.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.82-85
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• 2002

A systematic investigation for process design in deep drawing is necessary for quality improvement of drawn cups. This study has been concentrated mainly on the influence of process design scheme on product qualities in cylindrical cup drawing. Three types of process design scheme were chosen in this study. That is, Case 1 is to finish drawing a cup of 50m in diameter in one stage, Case 2 and Case 3 are redrawing the drawn cups of 55, 65 mm in diameter to the final size respectively. Though experiments the maximum drawing force in two-stage cup drawing could be reduced up to 35% as compared with that of one-stage cup drawing. In addition, the Case 2 and Case 3 processes showed better product qualities than the Case 1 process when comparing distributions of thickness, hardness, dimensional accuracy.

• Transactions of Materials Processing
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• v.3 no.4
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• pp.440-453
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• 1994

The multi-stage deep-drawing processes including normal-drawing, reverse-drawing, and re-drawing are analyzed by use of the rigid-plastic finite element method. Computational results on the punch/die loads and thickness distributions were compared with the experiments of the current drawing processes. Deep-drawing processes of the redesigned shell to improve the specific strength and stiffness were simulated with the numerical method developed. With varying several process parameters such as blank size, corner radii of tools, and clearances, the simulation results showed the improvements in reducing the forming loads. Also forming defects were found during simulation and appropriate blank size could be verified.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.242-245
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• 2007

In the present investigation, the multi-stage warm drawing process was applied to the magnesium alloy AZ31 sheet to examine the feasibility of multi-stage forming process as a high formability product making process. For that purpose, a multi-stage drawing die system with heating module was developed, and the AZ31 sheets of different sizes were consecutively drawn by the multi-stage drawing die. The obtained drawn cups of AZ31 showed that the multi-stage drawing provided the better formability than the single stage drawing in terms of drawing depth without cup defects such as wrinkles or fractures. The sheet formability improvement by using the multi-stage drawing die system against the single stage was also analyzed in terms of the finite element analysis of material state variables evolution.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.2936-2948
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• 1993

Multi-stage deep drawing is an important sheet metal forming process. The deformation mechanisms of sheet metals during forming processes are complicated mainly due to the geometry and the lubrication of tools involved, the formability and the anisotropic behaviour of the material. The multi-stage deep-drawing processes including normal-drawing, reverse-drawing, and re-drawing are analyzed by use of the rigid-plastic finite element method. The anisotropic behaviour represented by r-value can be incorporated into the formulation. Punch/die loads and thickness distributions were obtained as results of simulating axisymmetric deep drawing processes. The computed results showed good agreements with experiments.

• Transactions of Materials Processing
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• v.7 no.6
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• pp.562-569
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• 1998

The limit drawing ratio (LDR) is a major process parameter in the process design of deep drawing. If the actual drawing ratio is greater than the LDR for a particular stage then an intermediate stage has to b added the process sequence to avoid failure during the drawing operation and the optimal process design considering for the first-drawing and redrawing by using finite element method combined with ductile fracture criterion. From the results of finrte element analysis the optimal value of drawing ratio is obtained which contributes to the more uniform distribution of thickess and the smaller values of the ductile fracture infinal cup.

• Transactions of Materials Processing
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• v.12 no.7
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• pp.647-653
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• 2003

A systematic approach for the process design in deep drawing is necessary to improve the quality of drawn cups. This study concentrates mainly on the influence of process design strategy on the product quality. Different types of process design were chosen from initial blank of 100mm in diameter to make final cup of 50mm in diameter. In order to make this cup, we used 2-stage deep drawing. Forming analyses are carried out to find out better design in terms of drawing force. It is proposed that the process design, in which maximum drawing forces during successive operations are equal, is a more desirable one. Through experiment, it is found that the proposed case shows equivalent values in terms of maximum drawing force during successive operations in real process and can achieve the best product quality in terms of dimensional accuracy. Thus, it is shown that proposed design is very effective in the improvement of quality in drawn cups and may be extended to deep drawing with more stages.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.145-151
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• 1998

Unlike the drawing of round section from round bar, the shaped drawing like polygonal section is known to have influence not only drawing stress but also corner filling. Therefore. this study analyze the drawing process of suqare rod from round bar using nonsteady state rigid-plastic FEM. To investigate effects of process variables of the drawing process of square rod from round bar, FE-simulations with variety of reduction in area and semi-die angle for a given frictional condition have been conducted. By this results, it has to suggest optimal process condition on the drawing stress and the corner filling. In addition, it has determined forming limit considering necking and bulging.

• Journal of the Korean housing association
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• v.27 no.6
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• pp.137-144
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• 2016

In modular architecture, manufacturing drawing which includes whole information for modular unit production is essential since works for modular unit have to be performed in manufacturing factory not construction field. Although the manufacturing drawing is important as known it is insufficient to utilize the manufacturing drawing in modular architecture project and this makes modular unit low-quality with re-work and work time delay. To prevent low-quality modular unit caused by insufficient manufacturing drawing, in this research firstly manufacturing drawing's current situation and error cases in manufacturing phase of past modular housing project were analyzed, and correlation between reduction of errors occurance frequency and improving manufacturing drawing was verified. Secondly manufacturing drawing improvement factors were deducted in interior, furniture, mechanical work phase which errors' occurance rate is high and the way of deducting manufacturing drawing lists and contents were suggested with light-weight work as an example in case of new type of errors occurance. A series of research process can contribute to good-quality modular unit by errors reduction. As a result of research, about half of errors occurance can be reduced with suggested manufacturing drawing improvement factors. And the manufacturing drawing process can contribute to modular production which have uniform quality.