• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.101-108
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• 2010

The drum clutch investigated in this study is formed in 5 forming steps, which are 1st deep drawing, 2nd deep drawing, restriking, embossing, and $Grob^{TM}$ processes. Dimensional accuracy of the final products greatly depends upon how much more accurate pre-form is manufactured in the previous forming processes before the $Grob^{TM}$ process. The deep drawing, restriking and embossing processes in which the pre-form is formed are very important and decisive steps. Thus in some cases, excessive strain by these operations causes dimensional inaccuracy and cracks initiated from the base and wall of the product. Process variables such as the punch shapes both of 1st and 2nd deep drawing, and punch angle were selected to evaluate the deformation characteristics. The optimum parameters were determined from forming simulations using commercial FEM codes, DEFORM and Tauchi method, specifically developed for metal forming simulation. Finally, experiments for the whole drum clutch forming processes were carried out to verify the optimized forming parameters and the analytical results.

• Transactions of Materials Processing
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• v.21 no.6
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• pp.341-347
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• 2012

The metallic bipolar plates of the molten carbonate fuel cell(MCFC) are composed of shielded slot plates and a center-plate. The shielded slot plates support the center-plate and the membrane electrode assembly. Compressive forces are applied to the shielded slot plate in order to increase the contact area between shielded slot plates and the membrane electrode assembly (MEA). In the design of the shielded slot plate, it is necessary to predict the mechanical behavior of the shielded slot plate. The shielded slot plates are manufactured by a three-stage forming process consisting of slitting, preforming and the final forming process. The mechanical behavior of the shielded slot plate is largely affected by the forming process. In this study, the simulation of the three-stage forming process was used to predict the mechanical behavior of the shielded slot plate. The present simulation approach showed good agreements with the experimental results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.81-84
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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. In some drawing or stamping simulation with inverse method, it is difficult to apply inverse scheme due to the large aspect ratio or steep vertical angle of inclination. The reason is that initial guesses are hard to make out with present method for those cases. In this paper, a direct mesh marring scheme to generate initial guess on the sliding constraint surface described by finite element patches is suggested for one step inverse analysis to calculate initial blank shape. Radial type mapping is adopted for the simulation of rectangular cup drawing process with large aspect ratio and parallel type mapping for the simulation of S-Rail forming process with steep vertical angle of inclination.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.45-48
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• 1999

A program for initial blank design in sheet forming which contains the capabilities of forward loading simulation by the finite element method and backward tracking simulation has been developed and proved the effectiveness by applying to a square cup stamping process. In the blank design of square cup stamping the backward tracing program can produce an optimum blank configuration which forms a sound net-shape cup produce without machining after forming. Another general application appears in the blank design of a cup stamping with protruding flanges one of typical automobile components. The blank configurations derived by backward tracing simulation have been confirmed by a series of loading simulations. The approach for decision of an initial blank configuration presented in this study will be a milestone in fields of sheet forming process design.

• Transactions of Materials Processing
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• v.6 no.3
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• pp.233-238
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• 1997

The estimation of the forming force required for metal forming process is unavoidable for selecting suitable machine and dimensioning die and punch parts. For this purpose the upper-bound method turns out to be very practical in simple two-dimensional cases under well-known boundary conditions. However, the application of this method for complicated two-or three-dimentional cases is very limited or practically impossible. The modified application of FEM in a manner of applying the upper bound method(the so-called Upper-bound Finite Element Simulation Method) fortunately provides the posibility of getting important information about the forming process in a simple and quick way before realizing the process on the machine. It is expected to function successfully even in three-dimentional cases. The application procedure has been explained for two-dimensional cases and its usefulness shown.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.165-170
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• 1997

The study presents an computer-aided analysis and its design for the forming process of $\Omega$-type bellows tube. Finite element analysis was carried out to perform the process simulation. Based on the analytic results of various conditions, the forming conditions used for angled U-type bellows tube were settled. The 3D modeling was constructed by I-DEAS and PAM-STAMP was used for process simulation. It is concluded that the spring back of formed bellows influences $\Omega$-shape and these results can be used for the process design.

• Transactions of Materials Processing
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• v.3 no.4
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• pp.440-453
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• 1994

The multi-stage deep-drawing processes including normal-drawing, reverse-drawing, and re-drawing are analyzed by use of the rigid-plastic finite element method. Computational results on the punch/die loads and thickness distributions were compared with the experiments of the current drawing processes. Deep-drawing processes of the redesigned shell to improve the specific strength and stiffness were simulated with the numerical method developed. With varying several process parameters such as blank size, corner radii of tools, and clearances, the simulation results showed the improvements in reducing the forming loads. Also forming defects were found during simulation and appropriate blank size could be verified.

• Transactions of Materials Processing
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• v.7 no.6
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• pp.586-593
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• 1998

In recent automotive industries there has been significant increase in applications of computer simulation to the manufacturing of stamping dies for inner and outer body panels which greatly affect durability and aesthetic quality of automobiles. Enhancement of die quality and reduction of total die manufacturing time and consequently manufacturing cost are the visible outcome. However to successfully apply the result of simulation by a commercial package to the die manufacturing development of an optimal die manufacturing process is required upon the completion of analysis of forte and shortcoming of available sheet metal forming softwares. Based on the results of numerical analysis of front door outer panel forming. this paper evaluates the applicability of simulation results to the real die manufacturing for automotive body panels. Also it attempts to select an optimal die manufacturing process including design machining and tryout. Lastly it discusses the expected effects by adopt-ing the selected process in a real stamping die manufacturing facility.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06a
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• pp.33-40
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• 1998

In recent domestic automotive industry, applications of computer simulation to the manufacturing of stamping dies for inner and outer body panels which greatly affect durability and aesthetic quality of automobiles, have been increased. Enhancement of die quality, and reduction of total die manufacturing time and consequently manufacturing cost are the visible outcome. However, to successfully apply the result of simulation by a commercial package to the die manufacturing, development of an optimal die manufacturing process is required upon the completion of analysis of forte and shortcomings of available sheet metal forming softwares in the market. Based on the results of numerical analysis of front door outer panel forming, this paper evaluates the applicability of simulation results to the real die making for automotive body panels. Also, it attempts to select an optimal die manufacturing process including design, machining and tryout. Lastly, it discusses the expected effects by adopting the selected process in a real stamping die manufacturing facility.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.560-563
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• 2008

A condensed model is proposed for the simulation of forming of sandwich sheet with pyramid core. A corresponding finite element analysis for L-type bending is carried out to prove the accuracy and the effectiveness. Simulation results are compared with those of experiment. Deformation shape and post-buckling behavior by simulation are in good agreement with those of experiment for the considerable range of deformation. From the comparison of force-displacement curve, it is shown that the proposed model shows good prediction of the forming force compared to the experiment. Thus, the effectiveness of the proposed method is sufficiently demonstrated.