• Transactions of Materials Processing
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• v.11 no.8
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• pp.716-723
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• 2002

A systematic investigation 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 desing scheme on the product qualities in cylindrical cup drawing. Three types of process design scheme were chosen in this study. Case 1 is to draw a finished cup of 50mm in diameter in one stage, Case 2 and Case 3 are redrawing the first drawn cups of 55, 65mm in diameter to the final size respectively. Through experiments the maximum drawing force in two-stage cup drawing can be reduced up to 24% as compared with that of one-stage cup drawing. In addition, Case 3 process results in better product qualities than the other two processes in terms of the distributions of thickness and hardness.

• 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 the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1738-1750
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• 1994

Both cylindrical cup drawing and square cup drawing are analyzed using membrane analysis as well as shell analysis by the elastic-plastic finite element method. An incremental formulation incorporating the effect of large deformation and normal anisotropy is used for the analysis of elastic-plastic non-steady deformation. The computed results are compared with the existing experimental results to show the validity of the analysis. Comparisons are made in the punch load and distribution of thickness strain between the membrane analysis and the shell analysis for both cylindrical and square cup drawing processes. In punch load, both analyses show very little difference and also show generally good agreement with the experiment. For the cylindrical cup deep drawing, the computed thickness strain of a membrane analysis, however, shows a wide difference with the experiment. In the shell analysis, the thickness strain shows good agrement with the experiment. For the square cup deep drawing, both membrane and shell analyses show a wide difference with experiment, this may be attributable to the ignorance of the shear deformation. Concludingly, it has been shown that the membrane approach shows a limitation for the deep drawing process in which the effect of bending is not negligible and more exact information on the thickness strain distribution is required.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.1
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• pp.96-105
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• 1994

Cup drawing tests were performed to evaluate the friction characteristics of sheet metals. The linear relationship between drawing force and blank holding force obtained from the cup drawing test was used to calculate the coefficient of friction of the sheet metal. The friction coefficient was compared to that from conventional draw bead friction test. It was clarified that the cup drawing test can be used as a simple and convenient method for evaluating the friction characteristic of the sheet metal and also lubricity of the lubricant used.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.3
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• pp.198-204
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• 1993

The study is concerned with finite element analysis and design of axisymmetric deep drawing by local heating. When the bottom shape of a cup is not flat but in complex-shaped, i.e., hemispherical, the cup cannot be drawn in one or two processes in the conventional deep drawing process and the limit drawing ratio is limited as well. By introducing local heating selectively with regards to the heating position, the formability of the sheet metal can be greatly increased with the reduced number of processes. In the Process analysisthe rigid- viscoplastic finite element method is employed and the temperature effect is incorporated. Bishop's step-wise decoupled method is employed to analyze the thermomechanical interaction between deformation and heat transfer. Axisymmetric deep drawing of a hemisphere-bottomed cup has been analyzed for various combinations of heat application in the punch and the die. At the first stage of deep drawing stretch forming is practically carried out by firmly pressing the blankholder with the punch and the die heated at various levels of temperature. Then at the second stage the same cup is drawn for the saame or different combination of temperature. From the computation, it has thus been shown that the fromability of a cup is greatly increased in two-stage deep drawing with increased limet drawing ratio.

• Transactions of Materials Processing
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• v.20 no.1
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• pp.36-41
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• 2011

Meso-scale or micro-scale forming of sheet metal parts has been recently considered as one of the important forming technologies with growing demand on meso/micro products for electric or medical devices. Experimental investigation on the cylindrical meso-cup drawing with hemispherical punch is carried out to examine the limit drawing ratio and thickness distribution of drawn cups. The working parameters chosen in this study are blank diameter, die-corner radius and blankholding force. It is found from the experiments that the limit drawing ratio of 2.4 can be achieved in the case of hemispherical cup drawing and uniform thickness distribution in wider region can be obtained compared with the results of conventional cup drawing.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.34-39
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• 1999

IN this study when drawing a square cup blank holder pressure necessary for flange wrinkling prevention was experimentally studied. The materials used in the experiment were SPCC and SUS304 and drawing ratio was 1.62∼2.0 Two case for lubrication condition were experimented. One was without lubricant and the other was with lubrication of high viscosity.

• Transactions of Materials Processing
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• v.9 no.4
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• pp.356-361
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• 2000

In this study, when a square cup is under drawing, blank holder pressure necessary for flange wrinkling prevention was experimentally studied. The materials used in the experiment were SPCC steel and SUS304 and the drawing ratio was 1.62∼2.0. Two cases for lubricantion condition were investigated. One was without lubricant and the other was with lubricant of high viscosity.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.333-336
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• 2008

There are many different kinds of forming processes to make a tubular product such as hydroforming and tube drawing. However, we should consider a better forming process in view point of energy consumption and $CO_2$ emission to save our earth. In this paper we have conducted FEM simulations to the various forming processes for sheet and tubular products to compare their energy consumptions. One example is tubular product and the other for drawn cup. From the comparisons of total energy for hydrofroming and tube sinking processes, hydroforming is consumed more energy than tube drawing. Also the cup drawing from sheet metal and tube sinking for the cup with flange indicate that the tube sinking is better than cup drawing of sheet metal in energy consumption.

• 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.