• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.183-184
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• 2007

• Transactions of Materials Processing
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• v.8 no.4
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• pp.356-363
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• 1999

This paper discusses some techniques for the determination of optimum blank size and pre-form design for multi-stepped deep drawing of oval shell. The deep drawing process of oval shape has been regarded as more difficult than that of cylindrical shell because of its complicated behavior of plastic deformation. But there is insufficient information in this area to carry out successful deep drawing work of irregular products such as oval, rectangular, and square shapes. In order to find the optimum conditions, the drawing apparatus for two kinds of pre-form design are built, a series of drawing experiments performed, and thickness stain distributions measured. From the results of thess suggested experiments, various optimum process variables are observed and discussed.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.262-268
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• 1999

This paper reviews the rules for optimizing die design and the process variables such as die shoulder radius and punch to die clearance, which are important factors in drawing the sheet metal without failures during deep drawing. To find the optimum conditions for improving deep drawability, a series of the experiments are performed, and the wall thinning and thickening variations are investigated in each process of deep drawing for a complex cylindrical shell. From the results of this proposed experiment, the optimum values of process variables are examined and discussed, and the usefulness of the present suggestion is shown.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.4
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• pp.460-467
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• 1998

The investigation deals with the manufacturing process design and deformation analysis for seamless pressure vessels Axisymmetric multistage deep drawing is a complex and important sheet metal forming process in the industry. In this study the process design for large size cylindrical shells with various thickness is performed and a general guideline for forming process design of pressure vessels will be suggested. Thus in this paper for the verification of the forming process design the forming analysis of pressure vessels will be carried out by PAM-STAMP which is on the basis of finite element analysis. In this case the formability of pressure vessels is evaluated using the results of computer simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.302-307
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• 2016

The technology of multistage deep drawing has been widely applied in the metal forming industry, in order to reduce both the manufacturing cost and time. A battery can used for mobile phone production is a well-known example of multistage deep drawing. It is very difficult to manufacture a battery can, however, because of its large thickness to height aspect ratio. Furthermore, the production of the final parts may result in assembly failure due to springback after multistage deep drawing. In industry, empirical methods such as over bending, corner setting and ironing have been used to reduce springback. In this study, a bottoming approach using the finite element method is proposed as a practical and scientific method of reducing springback. Bottoming induces compression stress in the deformed blank at the final stroke of the punch and, thus, has the effect of reducing springback. Different cases of the bottoming process are studied using the finite element program, DYNAFORM, to determine the optimal die design. The results of the springback simulation after bottoming were found to be in good agreement with the experimental results. In conclusion, the proposed bottoming method is expected to be widely used as a practical method of reducing springback in industry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.320-326
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• 2017

Multistage deep-drawing technology is used widely in the production of mobile phone battery cases to improve productivity and economy. To ensure adequate capacity and rigidity, such cases are fabricated as a rectangular cup with a high slender ratio. The multistage deep-drawing of a rectangular cup entails a high slender ratio, and the heights of the product sides may be non-uniform because of the complicated deformation mechanisms. This causes problems in product assembly that affects the surface quality of the case. This study examined a blank shape that minimizes the height variations of the product to resolve the aforementioned problems. Optimization design and analysis were performed to identify the shape that yields the least variation. The long and short sides of an oval blank were set as the design variables. The objective function was set to yield the lowest height difference, and the thickness reduction rate of the product was set to the target range. In addition, the height of the final shape was set as a constraint. The height difference was minimized successfully using the optimized design. The design process of the initial blank for all rectangular shapes can be automated in the future.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.195-199
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• 2001

The flow turning process, an incremental forming process, is a cost-effective forming method for axi-symmetric intricate parts to net shape. However, the flow turning process shows a fairly complicated deformation, it is very difficult to obtain satisfactory results. Therefore extensive experimental and analytical research has not been carried out. In this study, an fundamental experiment was conducted to improve productivity with process parameters such as tool path, angle of roller holder($\alpha$), feed rate(v ) and comer radius of forming roller(Rr). These factors were selected as variables in the experiment because they were most likely expected to have an effect on spring back. The clearance was controlled in order to achieve the precision product which is comparable to deep drawing one. And also thickness and diameter distributions of a multistage cup obtained by flow turning process were observed and compared with those of a commercial product produced by conventional deep drawing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1016-1020
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• 2001

The spinning is a very effective manufacturing technology for short production runs in a variety of sizes and shapes, because it can form the cross-section or tubular parts various shapes. However extensive experimental and analytical research has not been carried out. In this study, and fundamental experiment was conducted to improve productivity with process parameter such as tool path, angle of roller holder(a), feed rate(v) and corner radius of forming roller(Rr). These factors were selected as variables in the experiment because they were most likely expected to have and effect on spring back. The clearance was controlled in order to achieve the precision product which is comparable to deep drawing one. And also thickness and diameter distribution of a multistage cup obtained by shear spinning process were observed and compared with those of a commercial product produced by conventional deep drawing.

• Transactions of Materials Processing
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• v.24 no.5
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• pp.323-331
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• 2015

Impact extrusion is an economical and productive process that can replace the multistage deep drawing process for producing deep rectangular cases. In the current work, a three-dimensional finite element analysis of the impact extrusion process of a commercial purity aluminum alloy (AA1070) was performed to predict loads, material flow, and deformed shapes using the Hansel-Spittel rheology law, which describes the flow stress at various temperatures and strain rates. The role of various process parameters such as friction, clearance between punch and die, aspect ratio and thickness of billet on the process and the shapes was analyzed.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.186-191
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• 2001

Spinning process is a chipless metal forming method for axi-symmetric parts, which is more economical, efficient and versatile method for producing parts than the other sheet metal forming process such as stamping or deep drawing. In this study, a fundamental experiment was conducted to improve productivity with process parameters such as tool path, angle of roller holder($\alpha$), feed rate($\gamma$) and corner radius of forming roller(Rr). These factors were selected as variables in the experiment because they were most likely expected to hale an effect on spring back. The empirical results were analyzed to know how much spring back was affected by these factors. And also thickness and diameter distribution of a multistage cup obtained by spinning process were observed and compared with those of a commercial product produced by conventional deep drawing.