• Transactions of Materials Processing
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• v.21 no.6
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• pp.348-353
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• 2012

Micro-drawn parts have received wider acceptance as products become smaller and more precise. The subject of this study was the deformation characteristics of ultra thin sheet metal in micro drawing of a rectangular shaped part. The influence of drawing speed and blank holding force on the product quality was investigated in micro-drawing of ultra thin sheet of beryllium copper (C1720) alloy. The specimen had a diameter of 4.8 mm and a thickness of $50{\mu}m$. Experiments were carried out in which, different blank holding force and drawing speed were considered. The product quality was evaluated by measuring the thickness and hardness along two specified directions, namely, the side and diagonal directions. The distribution of the thickness strain showed severe thinning especially around the punch radius in both directions. In the diagonal direction, thickening occurred in the flange area due to the axi-symmetric drawing mode. The increase of blank holding force and/or drawing speed was found to cause severe thinning around the punch radius. The blank holding force had a greater effect on thinning of the product than the drawing speed.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.68-71
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• 1998

Rectangular deep drawing process is widely used in sheet metal forming. But there are various defects such as earring, wrinkling, tearing, etc. In order to avoid the defects, an optimum blank shape is required. But it has not been generalized to determine the optimum blank shape because deep drawing processes are involved in complex process parameters. So, it is very necessary to do research systematically about determining the optimum blank shape of deep drawing process. In this study a rectangular cup drawing test has been carried out to determine the optimum blank shape for various stainless steel sheets. From the test, a new blank model, which has no earring, is proposed.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.1
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• pp.5-8
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• 2003

The rectangular deep drawing process is widely used in sheet metal forming, but there are various associated defects, such as earing, wrinkling, tearing, etc. In order to avoid such defects, an optimum blank shape is required. Such an optimum blank shape cannot be generalized because deep drawing processes are involved in complex process parameters. So, it is necessary to do systematic research to determine the optimum blank shape for the deep drawing process. In this study, a rectangular cup drawing test has been carried out to determine the optimum blank shape for various stainless steel sheets. From the test, a new blank model, which has no earing, is propsed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.97-100
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• 2000

Today deep drawing and ironing are the major process in manufacturing of battery case used in cellular phone from aluminum. The same technology is utilized in manufacturing of steel or aluminum cans for components of medical instrument, portable PC, walkman and so on. Most of these processes require multi-stage ironing following the deep drawing and redrawing processes. The practical aspects of this technology are well known and gained through extensive experiment and production know-how. However, the fundamental aspects of theses processes are relatively less known. Thus, it is expected that process simulations using FEM techniques would provide additional detailed information that could be utilized to improve the process condition. This paper illustrates the application of process modeling to deep drawing and redrawing operations for High Precision Rectangular Battery Case. A commercially avaliable finite element code LS-DYNA3D was used to simulate deep drawing and redrawing operations.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.05a
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• pp.56-59
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• 1999

In the present study, in order to investigate the effect of the corner filling in the drawing of the rectangular rod from a round bar, the drawing of the square rod from a round bar has been simulated by using rigid-plastic finite element method and artificial neural network has been introduced to reduce the number of simulation. The experimental investigation has been also implemented to verify the efficiency of the application of results of present and previous study. According to the results of present and pervious study, the combination of semi-die angle gives a great effect on the corner filling in case of the irregular shaped drawing process, but, in case of the regular shaped drawing process, the main process variable on the corner filling is reduction in area.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.105-108
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• 2000

Finite element analysis of a multi-stage deep drawing process is carried out for the die design of rectangular cup drawing with the large aspect ratio. Simulation is performed for thorough investigation of unfavorable mechanisms in the initial design. The analysis reveals that the difference of the drawing ratio and the irregular contact condition produces non-uniform metal flow to cause wrinkling and severe extension. In this paper, the modification guideline is proposed in the design of the process and the tool shape. The analysis result confirms that the modified design not only improves the quality of a deep-drawn product but also reduces the possibility of failure.

• Design & Manufacturing
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• v.16 no.2
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• pp.60-65
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• 2022

In the pultrusion process for the CFRP (Carbon fiber reinforced plastic) rectangular pipe, the drawing device is eseential which can continuously produces products and draws the carbon fiber tow. In addition, since the degree of cure changes depending on the temperature and the temperature ditribution of the curing mold changes depending on the pultrusion speed, the temperature distribution of the curing mold under certain conditions must be studied before processing. In this study, in the pultrusion process using a closed impregnation method, which has several advantages compared to the general pultrusion process using a open bath impregnation method, the drawing force required to pull the carbon fiber tows and the temperature distribution of the curing mold was analyzed to design the drawing device and the curing mold efficiently.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1077-1084
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• 2002

Optimum tool design is carried out fur a multi-stage rectangular cup deep-drawing and ironing process with the large aspect ratio. Finite element simulation is carried out to investigate deformation mechanisms with the initial design made by an expert. The analysis considers the deep drawing process with ironing for the thickness control in the cup wall. The analysis reveals that the difference of the drawing ratio within the cross section and the irregular contact condition produce non-uniform metal flow to cause wrinkling and severe extension. For remedy, the modification guideline is proposed in the design of the tool and the process. Analysis results confirm that the modified tool design not only improves the quality of a deep-drawn product but also reduces the possibility of failure. The numerical result shows fair coincidence with the experimental one. After tryouts of the tool shape, the rectangular cup has been produced in the transfer press.

• Transactions of Materials Processing
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• v.17 no.3
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• pp.170-181
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• 2008

The shape of rectangular cup used for Ni-MH(Nickel-coated Metal Hydrogen) battery for hybrid car looks quite simple, but the forming process of extruding and setting up process design are highly difficult. Furthermore, there are few concrete reports on the rectangular deep drawn cup as part of hybrid vehicles till now. In this study, process design for rectangular cup in the multi-stage deep drawing process is carried out, and FE analysis is also preformed based on the result of the process design. From the simulation result, some unexpected problems such as earing, wrinkling and excessive thickness changes of the intermediate blank occurred. To overcome these failures, a series of modification for punch shape in the forming process design are completed and applied. Considering the modified punch shape in the multi-stage deep drawing process, additional FE analysis is also carried out and the simulation result is verified in view of the deformed shape, thickness change and effective strain distribution. The result of FE analysis with the improved process design confirmed not only reducing thinning of wall and possibilities of failure but also improving the quality of drawing product through the modification of punch shape.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.94-97
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• 2001

An inverse finite element approach is employed for more capability to design the optimum blank shape from the desired final shape with small amount of computation time and effort. For multi-stage deep-drawing processes, numerical analysis is extremely difficult to carry out due to its complexities and convergence problem as well as tremendous computation time. In this paper, multi-stage finite element inverse analysis is applied to multi-stage rectangular cup drawing processes to calculate intermediate blank shapes and strain distributions in each stages. Deformation history of the previous stage is considered in the computation. Finite element patches are used to describe arbitrary intermediate sliding constraint surfaces.