• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.230-233
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• 2008

Stainless steels are alloy steels with iron as the primary constituent and chromium, nickel, and manganese as principal alloying elements. In addition to automotive, construction, and transportation industries, stainless steels have a variety of applications in the food, chemical, and pharmaceutical industries. Some common products made from stainless steel are sinks, wash basins, kitchen vessels, and cutlery. Among ferritic stainless steels, type 409 can be cold-formed easily and are used for deep-drawn parts such as vessels for the chemical and food industries. In this study, forming analyses and experiments to prevent the occurrence of inferiority such as wrinkles, crack, and neck for automotive muffler part are carried out to save the optimal conditions during forming by modifying the blank size and shape, blank holding force etc.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.375-378
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• 2009

Hot press forming is a new forming process which also names as hot stamping. It can greatly enhance the formability of forming parts. This paper researches the formability of boron steel sheet in hot bending process which is a kind of hot press forming. In the text, the influence of hot press forming processing parameters, such as the heating temperature, blank holding force, punch speed and punch and die radius, on the mechanics properties and microstructure of the hot bending parts was analyzed by tension test and the metallographic observation on the parts with various processing parameters. The relationship between blank holding force and punch load was also presented.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.85-88
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• 2001

Deep drawing process, one of sheet metal forming methods, is used widely. Circular or square shape blanks are currently studied mainly. Especially, circular blank for coating case of chip condenser remains bridges when it is made out of aluminum coil. The bridge reduces Material-withdrawal-rate of aluminum coil to $60\%$. This paper proposes a no-bridge blank instead of circular blank. To get the different values of two cases, comparison circular blank with no-bridge blank is accomplished in the point of thickness strain in the vicinity of flange. In order to find optimal condition in new proposed blank, several process variables - those are blank holder shape, die shape radii, punch shape radii and blank holding force - are changed.

• 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.

• Journal of Power System Engineering
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• v.7 no.2
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• pp.61-65
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• 2003

Sheet metal forming process is a non-linearity problem which Is affected by various process variables, such as geometric shape of punch and die, frictional characteristic, etc.. Therefore, the knowledge of the influence of the process variables is needed in the design of sheet metal working processes. In this paper, deep drawing tests for blank holding force, punch speed and lubrication between sheet material and tool were carried out to investigate the influence upon sheet formability. Experimental results were discussed about the defects on the deformation behaviors during the forming process.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.164-170
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• 2003

To ensure the reliability of DVDR-P and DVD-ROM, it is imperative to remedy the unrecoverable creep deformation and/or relaxation of the holding force of an optical disc holder. To predict the deformation of an optical disc holder, a deformation analysis of an 80 mm optical disc holder considering the creep characteristics of 3 plastic materials has been conducted. Subsequently, the results by this Finite Element Analysis (FEA) are experimentally verified. A disc holder inserted in a cartridge case is kept in a chamber of $60^{\circ}C$ with 90 % humidity for 24 hours. The arm span and the holding force of the disc holder are measured after being left for another 24 successive hours at a room temperature and under normal humidity. The predicted results by FEA are in good agreement with experimentally measured values.

• Transactions of Materials Processing
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• v.3 no.4
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• pp.454-467
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• 1994

The drawbead restraining forces for the various radius of drawbead and die corner are analyzed by the belt theory, and they are compared with the experimental results. During this procedure, the drawing angles are also varied from $0^{\circ}$ to $60^{\circ}$, and the near part of the drawed die corner are divided into fur steps for the theoretical analysis. The stress distributions through the sheet thickness for these steps are also suggested theoretically. The wide range of experimental data of the drawing forces and strain distributions for the various dimension and blank holding forces are presented. It is concluded that the theoretical assumption for the restraining force analysis is very useful from the comparison with the experimental results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.48-52
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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, 100 mm/min), thickness (0.5, 0.8, 1.0, 1.4 mm). 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. 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 of Precision Engineering Conference
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• 2003.06a
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• pp.1593-1596
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• 2003

Sheet metal forming process is a non-linearity problem which is affected by various process variables, such as geometric shape of punch and die, frictional characteristic, etc.. Therefore, the knowledge of the influence of the process variables is needed in the design of sheet metal working processes. In this paper, deep drawing tests for blank holding force, punch speed and lubrication between sheet material and tool were carried out to investigate the influence upon sheet formability. Experimental results were discussed about the defects on the deformation behaviors during the forming process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.19-24
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• 1997

The weld line location and the weld line movement in stamping with laser-tailor welded blanks(TWB) were investigated through square cup deep drawing tests. The step blank holder was introduced to form TWB of different thicknesses without wrinkling, and the non-uniform blank holding force(BHF) was enforced to control weld line movement. Test results of the blanks with shifted weld lines showed that the large portion of the thinner area could result in a large weld line movement. Careful selection of the weld line location and the BHF control should be adapted in TWB design to avoid failures and to ensure its formability.