• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.129-133
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• 2000

It is reasonable to use the stereo vision and image processing technique to digitize 3D coordinates of grid points and to evaluate surface strains on a sheet metal parts. However this method has its intrinsic problems such as the difficulty in enhancement of bad images inevitable error due to digital image resolution of camera and frame grabber unreliability of strains and thickness evaluated from coarse grid on the corner area with large curvature and the limitation of the area that can be measured at a time. Therefore it is still hard to measure strain distribution over the entire surface of a medium,- or large-sized stamped part at a time even by using an automated strain measurement system. In this study the curvature correction algorithm based on the grid refinement and the geometry assembling algorithm based on the global error minimization (GEM) scheme are suggested. Several applications are presented to show the reliability and efficiency of these algorithms.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.231-234
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• 2001

Shearing, including blanking, trimming, piercing, etc, is one of the most frequently used processes in sheet metal manufacturing. In this paper, an individual set of tooling with an in-die sensor was designed and precisely fabricated to carry out the experiment for the shearing process investigation. Through various experiments, it has been examined the influence of process parameters such as clearance, edge material properties and pad configuration. Since the tension between the part and the scrap increases when the clearance increases, the clearance should be selected properly in order to reduce the burr height. Also removal of the lower pad makes the sheared surface worse and the shearing system unstable. The shearing force increases when the clearance decreases and the friction of the tooling material decreases. Dynamic reaction force is also important to obtain the fine sheared surfaces.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.06b
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• pp.185-194
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• 1999

This paper suggests the new techmology to control metal flow in order to reduce the number of preforming and machining for the cold forged product with complex geometry. This technology can be summarized the complex forming, which consists of bulk forming and sheet forming, and multi-action forging, which be preformed double action dies. To analyze the process, finite element simulation has been performed. The proposed technology is applied to hub which is part of air conditioner clutch. According to the result of this study, the relative velocity of mandrel and punch is primary process variable.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.287-291
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• 2001

In this study, we designed and constructed a multi-forming progressive die with a bending, embossing on the multi-stage and performed through the try out. Out of the characteristics of this paper that nothing might be ever seen before such as this type of research method on the all of processes of thin and high precision production part.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.80-85
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• 2002

The progressive die for U-bending production part is a very specific division. This study reveals the Sheet metal forming process with multi-forming die by Center Carrier type feeding system. Through the FEM simulation by DEFORM it was accepted to u-bending process as the first performance to design in strip process layout design. The next process of die development was studied according to sequence of die development.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.06a
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• pp.163-172
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• 1994

The Aerospace and automobile industries have need to avoid sheet-metal forming problem such as incorrect springback after forming and trimming process, excessive thinning/tearing, wrinking/perkering. It is common practice to use costly trial-and-error experimental methods to develop tooling and manufacturing process parameters. Experimentation should be complemented with computer simulation to reduce cost and leadtime in manufacturing and to influence the design of components. In this study, firstly we solved the springback problem after drawing and trimming process of KFP(F100-229) engine airsealing bearing support part(53H00) forming and studied on the effect of several process parameters on the gap between the formed blank and punch shape using the implicit F.E.M code(ABAQUS). Secondly by the three dimensional dynamic analysis using the explicit. F. E. M code (LS-DYNA3D), we studied on the effect of several process parameters which can be used for avoid tearing and wrinking during the drawing process.

• 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.

• Design & Manufacturing
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• v.14 no.4
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• pp.65-70
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• 2020

Partial reinforcement of sheet metal parts with CFRP patch is a technology that can realize ultra-lightweight body parts while overcoming the high material cost of carbon fiber. Performing these patchworks with highly productive press equipment solves another issue of CFRP: high process costs. The A-pillar is the main body part and has an undercut shape for fastening with other parts such as roof panels and doors. Therefore, it is difficult to bond CFRP patches to the A-pillar with a general press forming tool. In this paper, a flexible system that applies uniform pressure to complex shapes using ceramic particles and silicone rubber is proposed. By benchmarking various A-pillars, a reference model with an undercut shape was designed, and the system was configured to realize a uniform pressure distribution in the model. The ceramic spherical particles failed to realize the uniform distribution of high pressure due to their high hardness and point contact characteristics, which caused damage to the CFRP patch. Compression equipment made of silicone rubber was able to achieve the required pressure level for curing the epoxy. Non-adhesion defects between the metal and the CFRP patch were confirmed in the area where the bending deformation occurred. This defect could be eliminated by optimizing the process conditions suitable for the newly developed flexible system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.632-635
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• 2008

Concurrent engineering concept is used in factory automation recently. In this paper, described instance that apply concurrent engineering production concept in sheet metal cutting process. Automation system to produce metal parts designed by Client/server structure, and designed NC postprocessor on inside. Also, in this paper, when handled all justices of part production by breakup design of concurrent engineering, proved can shorten tine required in product manufacture than system past.

• Transactions of Materials Processing
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• v.9 no.6
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• pp.574-581
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• 2000

A vertically-walled auto-body part is one of the most difficult stamping parts because of angle change, wall curl, and twisting of the blank after springback as well as fracture and wrinkle. In this study, computational simulations of the vertically-walled auto-body part are carried out focusing on angle change, wall curl, and twisting after springback. Binderwrap blank shape is used in forming analysis for precise initial contacts between punch and blank. An adaptive mesh method is used in springback analysis for precise calculation of bending moments. In springback analysis, the differences of 2 and 3 dimensional analysis are compared and the effects of blank holdig force and friction coefficient are evaluated. In order to verify the validity of simulation results, they are compared with measured ones. The predicted thickness distribution and formed shape are agreed well with those of the measurement. The Predicted springback amount is less than that of the measurement.