• Transactions of Materials Processing
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• v.17 no.6
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• pp.429-435
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• 2008

In this paper, the serrated forming process is analyzed with finite element method. The seal should secure the overlapping portions of ligature, which has teeth for ligature to prevent from slipping each other after clamping. In the simulation, rigid-plastic finite element model has been applied to the serration forming process. Serration or teeth forming characteristics has been analyzed numerically in terms of teeth geometry based on different forming conditions. Analyses are focused to find the influence of different die movements and geometries on the tooth geometry, which is crucial for securing overlapping portions of ligature. Two major process variables are selected, which are the face angle and entry angle of punch, respectively. Extensive investigation has been performed to reveal the influences of different entry and face angles on the geometry of teeth formation in the simulation. Three different face angles of punch have been selected to apply to each simulation of serrated sheet forming process with every case of punch entry angles. Furthermore, tooth geometries predicted from simulation have been applied to the indention process for comparing proper tooth geometries to secure the sealing.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.6 s.183
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• pp.52-56
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• 2006

Punching tools like an electrodes are made by milling or etching or EDM. These methods had time consuming, low efficiency and air pollution. So, we have developed a shearing device which counter punching method for burrless cutting of micro wire. Using the straightened SUS304 wire with $200{\mu}m$ diameter, we confirmed the tendency of the shear plane for punch tools. It was impossible to completely remove the bun in the shearing process. In order to minimize the burr size and fine shear plane, we have accomplished the various experiment conditions such as the U-groove, the effect of the counter punch, shear angle and clearance. The results of the experiments show that indentation, slip plane and bent shape were related to the shear angle and clearance.

• Transactions of Materials Processing
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• v.15 no.3 s.84
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• pp.226-231
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• 2006

The fuel injector is a pa.1 that controls the fuel supply of automotive engine. The housing of the fuel injector supports the rod, the needle valve and the solenoid. In this study, the rigid-plastic FE-analysis by using the design of experiments (DOE) and the response surface methodology (RSM) has been performed to produce the product reducing the under-fill and the maximum effective strain. From the results of DOE, the stem of counter punch and the face angle of punch at the $1^{st}$ process, and the stem of punch at the $2^{nd}$ process were determined as the significant design variables far each response such as the upper under-fill, lower under-fill and the maximum effective strain. From the results of RSM, the optimal values of the design variables have been also determined by simultaneously considering the responses.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.144-149
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• 1996

In this paper, the clamping type forging of helical gears has been investigated. Clamping type forging is an operation in which the product is constrained to extrude sideways through an orifice in the container wall. Punch is cylindrical shaped. The punch compresses a cylindrical billet placed in a die insert. As a consequence the material flows in a direction perpendicular to that of punch movement. The forging has been analysed by using the upper-bound method. A kinematically admissible velocity field has been developed, wherein, an involute curve has been introduced to represent tooth profile of the gear. Numerical calculations have been carried out to investigate the effects of various parameters, such as module, number of teeth, helix angle, friction factor and initial height of billet on the forging of helical gears.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.6
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• pp.56-62
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• 2011

In this study, a method for the press forming of rectangular aluminium tube has been proposed. Rectangular aluminium tube has high stiff as the cold steel which can be lighter over 30% weight. It is increased every year by being recycled over 80%. Press die consists of punch, wing-die and holder for aluminium tube bending. When punch is applied with aluminium tube, holder is operated as same punch and wing-die is rotated through hinge. Stress-strain relations and springback are considered by bending angle of aluminium tube. In this study, the behaviors on tubes of square aluminium and rectangular aluminium with different thickness and area are established by the analysis of $DEFORM^{TM}$-3D program. Reducing fuel consumption is expected by using the aluminium tube deformation and it becomes the lightweight through recycling.

• Korean Journal of Applied Biomechanics
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• v.13 no.3
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• pp.293-309
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• 2003

The purpose of this study was to analyze the kinematic variables of the right-straight punch(RSP) in boxing with three-dimensional analysis technical methods. The subjects are boxers who have been playing in national boxing representative team and the RSP is their special favorite technique, The right-straight punches were filmed on 16mm video cameras(30frames/sec.) The kinematic variables were temporal, postural and center of gravity(COG). The mean and the standard deviation of variables have been obtained and used as basic factors for examining characteristics of the RSP by out-boxers. From the data analysis and discussion, the following conclusions have been drawn. 1) Temporal variables It is a significant characteristic that LDJ and KDM s' the amount of elapsed time(EF) needed for both an attack and a defense were similar : ET for stretch-out of attack-arm was $0.52{\pm}0.04\;sec$. and return was $0.54{\pm}0.01\;sec$. Therefore, a defense motion is as important as an attack motion. 2) Posture variables When the subjects performed a RSP, the significant characteristic of the ankle angle was that it wasn't completely returned to the original position after stretching-out. Therefore it is necessary to do supplementary exercises, such as side steps, to move the center of gravity more effectively. The hee angle was not fully stretched either. In regard to the hip angle, it should be rotated with all strength to harmonize with the direction of movement. 3) Center of Gravity(COG) variables When both LDJ and KDM performed a RSP, a significant characteristic was the transformation of sagittal view rather than transverse or frontal views.

• Transactions of Materials Processing
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• v.25 no.1
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• pp.29-35
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• 2016

In the current study, finite element analysis was conducted for the press hemming of automotive panels in order to predict various hemming defects such as roll-in and turn down. The analysis used the exact punch movement based on the cam location and considered the sealer between the inner and outer panels with an artificial contact thickness. The analysis results quantify the hemming defects especially at the flange edge in the matching region of the head lamp. A design of experiments along with the parameter study was used to obtain the optimum process parameters for minimizing hemming defects. The optimization process selects the intake angle, bending angle of the hemming punch, and the flange height of the outer panel. The optimum design process determines an appropriate tool angle and flange height to reduce the roll-in and turn-down as compared to the initial design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4057-4064
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• 2014

In this paper, attempts were made to design a preform for a final punch inexpensively using the proposed approximate optimization method or metamodel-based simulation optimization. The design objective of this work is to achieve a uniform distribution of effective strains, the angle dimension of the preformed punch is chosen as a design variable, and maximum underfill ratio is used as a constraint. For this optimization, a computer simulation of a practical punch forging process is run using DEFORM software, in which a preformed punch(workpiece), a master punch(upper die), and a bottom die are dealt with. A validation method is introduced to determine if the simulation results match the actual forging process. In addition, this work presents the detailed design optimization procedure consisting of (i) generation of an initial metamodel, (ii) metamodel optimization, (iii) validation of metamodel-predicted optimum, and (iv) metamodel improvement.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.277-280
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• 2003

It was investigated that the "ㄱ" type angle product could be bended with a curvature during extrusion by extru-bending process. The bending process for the "ㄱ" type angle product can be developed by the hot metal extru-bending machine with the two punches moving in the different velocity. Because of non-symmetry of product, it is important to design the ruled surface contour of dies cavity for the welding and bending with two billets. So it is designed that the multi-hole container has two non-symmetric holes and non-symmetric contour of dies entrance. The results of the experiment show that "ㄱ" type angle product can be bended by the extrusion process and that the curvature of the product can be controlled by the velocity of punch and that the defects such as the distortion of section and the thickness change of the product and the folding and wrinkling of the product did not happen after the bending processing by the extrusion bending machine.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.11a
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• pp.23-32
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• 2002

The torsional forward extrusion is the process that is executed by punch travel and die rotation. The advantages of having the die rotation on this process are that forming load can be reduced and optimal die angle can be increased. This provides a possibility to extrude cold-worded material where a large extrusion force and die angle are required. Also, this process can improve the material properties owing to the high deformation and uniform strain distribution. The forming load and optimal die angle of this process are determined by the upper bound analysis using stream function and the optimization technique. To verify the theoretical result, we have carried out experiments and FE simulations using DEFORM3D.