• 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 Materials Processing
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• v.4 no.4
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• pp.302-321
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• 1995

A method of determining an optimum blank shape for the non-circular deep drawing process is investigated. The rigid-plastic finite element method is introduced and the computer program code is developed. The ideal shape of a drawn cup with uniform wall height is assumed and metal flow is traced back-ward step by step to predict an initial blank shape of the ideal cup. For examples of the non-circular deep drawing products, three cases of drawn cup with quadrilateral punch shape are considered and optimum blank shapes for each case are proposed and compared with experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1950-1956
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• 2017

In food-printing field, precise positioning technique for a printing object is very important. In this paper, we propose cup positioning method for a latte-art printer through image processing. A camera sensor is installed on the upper side of the printer, and the image obtained from this is projected and converted into a top-view image. Then, the edge lines of the image is detected first, and then the coordinate of the center and the radius of the cup are detected through a Circular Hough transformation. The performance evaluation results show that the image processing time is 0.1 ~ 0.125 sec and the cup detection rate is 92.26%. This means that a cup is detected almost perfectly without affecting the whole latte-art printing time. The center point coordinates and radius values of cups detected by the proposed method show very small errors less than an average of 1.5 mm. Therefore, it seems that the problem of the printing position error is solved.

• Transactions of Materials Processing
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• v.15 no.7 s.88
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• pp.504-511
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• 2006

The drawability of AZ31B magnesium sheet is estimated at various temperatures($200,\;250,\;300,\;350\;and\;400^{\circ}C$), and forming speed(20, 50, 100mm/min), thickness(0.5, 0.8, 1.0, 1.4mm). The deep drawing process of circular cup and square cup were used in forming experiments. Experimental and FEM analysis are performed to investigate drawability and affection of controlled blank holding force. Through the controlled blank holding force, drawability was improved. Limit drawing ratio is increased from 2.1 to 3.0 in circular cup drawing and change of thickness is decreased from 16.3 to 6.9%. This result is verified by FEM analysis. Through the observation of microstructure, the main cause is investigated as a quantity of the dynamic recrystallization.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.556-559
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• 2008

In this study, the failure in circular cup deep drawing simulation at warm temperature is predicted using forming limit diagram (FLD). The FLD is used in sheet metal forming analysis to determine the criterion for fracture prediction. The simulation with heat transfer of circular cup deep drawing at warm temperature was conducted. To predict the failure, the simulation with heat transfer used FLD at temperature in the vicinity of maximum thinning. The result of the simulation with heat transfer shows that the drawn depth increases with increasing temperature and is in accord with the experimental results above $150^{\circ}C$. The FLD provides a good guide for the failure prediction of warm forming simulation with heat transfer.

• Journal of the Korean Mathematical Society
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• v.34 no.1
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• pp.43-55
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• 1997

Suppose that D is a domain in the extended complex plane $\overline{C} = C \cup {\infty}$. For each $z_0 \in C$ and $C < r < \infty$, we let $B(z_0, r) = {z \in C : $\mid$z - z_0$\mid$ < r}$ and $S(z_0, r) = \partial B(z_0, r)$. For non-empty sets A, $B \subset \overling{C}$, diam (A) is the diameter of A and d(A, B) is the distance of A and B.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.406-411
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• 2003

It is clearly demonstrated that deeper cups could be formed by single and double stretch-drawings from smaller circular blanks due to such wall-thinning action than in the usual deep-drawing of larger blanks. From this fact, it is emphasized that the deep-drawability of a sheet metal Is not evaluated simply by the conventional L.D.R (limiting drawing ratio), but the depth of the drawn cup should also be taken into account. Many experimental data about various metals and thicknesses given in this paper offer a valuable information in this process for more general use which recommends to replace the conventional deep-drawing process by the stretch-drawing process both for single and double operations. In the single stretch-drawing, it is also confirmed that a deeper cup can be produced by raising the blank-holding force at later stage of operation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1129-1137
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• 1990

Based on the formulation which incorporates large deformation and anisotropy, an elastic-plastic finite element code is developed with membrane element to include the contact treatment. For the analysis of the general sheet metal forming process with contact condition, the treatment of contact is considered by employing the successive skew coordinate system. Three kinds of sheet metal forming processes with contact conditions are analyzed; stretching of a square diaphragm with a hemispherical punch, deep drawing of a circular cup and deep drawing of a square cup. Then the computational results are compared with the experiment. The computed loads and the distribution of the thickness strain are in good agreement with the experiment for all cases. However, the computational results of the thickness strain show the effect of bending can not be ignored in the deep drawing process whereas the effect of bending is negligible in stretching.

• Transactions of Materials Processing
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• v.21 no.1
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• pp.49-57
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• 2012

It is difficult to estimate the properties of multilayered sheet because they are composed of one or more different materials. Plastic deformation behavior of the multilayered sheet is quite different as compared to each material individually. The deformation behavior of multilayered sheet should be investigated in order to prevent forming defects and to predict the properties of the formed part. In this study, the mechanical properties and formability of stainless steel-aluminum-magnesium multilayered sheet were investigated. The multilayered sheet needs to be deformed at an elevated temperature because of its poor formability at room temperature. Uniaxial tensile tests were performed at various temperatures and strain rates. Fracture patterns changed mainly at a temperature of $200^{\circ}C$. Uniform and total elongation of multilayered sheet increased to values greater than those of each material when deformed at $250^{\circ}C$. The limiting drawing ratio (LDR) was obtained using a circular cup deep drawing test to measure the formability of the multilayered sheet. A maximum value for the LDR of about 2 was achieved at $250^{\circ}C$, which is the appropriate forming temperature for the Mg alloy. Fracture patterns on a circular cup and thickness of formed part were predicted by a rigid-viscoplastic FEM analysis. Two kinds of modeling techniques were used to simulate deep drawing process of multilayered sheet. A single-layer FE-model, which combines the three different layers into a macroscopic single layer, predicted well the thickness distribution of the drawn cup. In contrast, the location and the time of fracture were estimated better with a multi-layer FE model, which used different material properties for each of the three layers.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.123-128
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• 2000

Fundamental and informative data of axi-symmetric stretch-drawing of several sheetmetals with thicknesses of 0.7-1.0mm are presented both for single and double operations. Very small radius is applied to the die profile (or-shoulder) ion all operations. to induce wall-thinning by the effect of bending-under-tension from which the name 'stretch-drawing' comes. It is clearly demonstrated that deeper cups could be formed by single and double stretch-drawings from smaller circular blanks due to such wall-thinning action than in the usual deep-drawing of larger blanks, From this fact it is emphasized that the deep-drawability of a sheet metal is not evaluated simply by the conventional L.D.R (limiting drawing ratio) but the depth of the drawn cup should also be taken into account./ Many experimental data about various metals and thicknesses given in this paper offer a valuable information in this process for more general use which recommends to replace the conventional deep-drawing process by the stretch-drawing process both for single and double operations. In the single stretch-drawing it is also confirmed that a deeper cup can be produced by raising the blank-holding force at later stage of operation.