• Transactions of Materials Processing
• /
• v.11 no.6
• /
• pp.513-518
• /
• 2002

The equivalent boundary conditions have been applied to the front door panel forming process, in order to demonstrate its reliability and validity. The elongation in the bead forming process is applied to the binder wrap process as the equivalent displacement boundary condition and the restraining force in the drawing process is applied to stamping process as the equivalent force boundary condition. The result calculated with the equivalent boundary conditions shows closer coincidence with the experimental result than simulation with different boundary conditions. The numerical result fully demonstrates that drawbead forming simulation for calculation of equivalent boundary conditions is necessary and effective.

• Journal of the Korean Society of Industry Convergence
• /
• v.20 no.2
• /
• pp.141-148
• /
• 2017

A process comprising a hot extrusion process and a warm forging process was designed to form a T-shaped aluminum structural component with a high degree of difficulty by the plastic forming method. A circular cylindrical part was extruded with a hot extrusion process, and then an embossing part was formed with a warm forging process. The formability and the maximum load required for forming were then determined using a forming analysis program. The hot extrusion process was executed at $450^{\circ}C$ under the extrusion speed at 6 mm/s, while the warm forging process was executed at $260^{\circ}C$ under the forging speed at 150 mm/s. For both the processes, a condition by which friction would not be generated between the mold and the material was implemented. The analysis results showed that the load required for hot extrusion was 1,019 tons, while the load required for the warm forging was 534 tons. The T-shaped part was manufactured by using a 1,600 tons capacity press. The graphite lubricant was coated on the mold as well as the material. A forming experiment was performed under the same condition with the analysis condition. The measured values from the load cell were 1,210 tons in the hot extrusion process and 600 tons in the warm forging process.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.1313-1314
• /
• 2011

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.1082-1086
• /
• 2004

Since the sheet forming of Mg alloy has many difficulties due to the low formability, many forming conditions need to be selected properly. Especially, the process variables should be investigated to increase the formability, such as, forming temperature. In this paper, the effects of forming process variables has been investigated using the bending and deep drawing process. A simple U-bending designed for mobile part could be formed in room temperature and springback amounts are surveyed. On the other hand, square cup part couldn't be formed in room temperature due to the low formability. Therefore, the effects of forming temperature are investigated in deep drawing process for square cup part. As a experimental and FEM results, the optimum forming temperature is presence and formability in a higher temperature is less than that of lower temperature. Above experimental results are compared with the FEM analysis and well coincided with the experimental results. Therefore, more detail investigations could be progressed to select more appropriate process conditions by the FEA.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.05a
• /
• pp.445-449
• /
• 2009

With the recent increase in the demand for the net-shape forming, numerical simulations are being commonly adopted to increase the efficiency and effectiveness of design of bulk metal forming processes. Proper consideration of tribological problems at the contact interface between the tool and workpiece is crucial in such simulations. In other words, lubrication and friction play important roles in metal forming by influencing the metal flow, forming load and die wear. In order to quantitatively estimate such friction condition or lubricant characteristic, the constant shear friction model is widely used for bulk deformation analyses. For this, new friction testing method based on the forward or backward extrusion process is proposed to predict the shear friction factor in this work. In this method, the tube-shaped punch pressurizes the workpiece so that the heights at the center and outer of punch (or mandrel) become different according to the friction condition. That is, the height at the center of punch is higher than that at the outer of the punch when the friction condition at the contact interface is severe. From this founding, the proposed friction testing method can be applied to effectively evaluate the friction condition in bulk metal forming processes.

• Journal of the Korean Wood Science and Technology
• /
• v.23 no.4
• /
• pp.74-84
• /
• 1995

Eight types of thin composite panels were manufactured by press-lam and mat-forming process applied to optimum manufacturing condition, studied in former first research by author (1995). They were tested and compared with control boards on dimensional stability, internal bond strength, tensile strength, Screw withdrawal strength, and bending properties. These thin composite panels manufactured by mat-forming process were generally superior to those by press-lam in dimensional stability and mechanical properties. In the dimensional stability and mechanical properties of thin composite panels manufactured by mat-forming process, the thin composite panels (A and E type) composed of particle or sawdust core and veneer face with polyethylene film, were as good as those of common plywood (control board). Internal bond strength showed highest value in the thin composite panel(D type) which composed of particle core and polypropylene screen face with polyethylene film. The thin composite panels(G and H type) composed of sawdust or particle core and polypropylene screen face with polyethylene film by press-lam and mat-forming process, showed most highest value in dimensional stability and water absorption.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.236-239
• /
• 1995

In this paper,Upper bound analysis to predict the formation of corner cavity during the final stage of backward extrusion is used. The critical condition for corner cavity formation is obtained by upper bound analysis. The quantitive relationships between corner cavity formation and process parameters are studied. To broaden forming limit area, driven container and multi-step forming process is proposed. As a result of FEM, forming limit is enlarged. And this results is compared with the analytric results

• Journal of the Korean Society of Industry Convergence
• /
• v.20 no.3
• /
• pp.221-232
• /
• 2017

In this study, bipolar plates in fuel cells are formed using rubber forming process. The effects of important parameters in rubber forming such as hardness and thickness of rubber pad, speed and pressure of punch that compress blank, and physical property of materials on the channel depth were analyzed. In the soft material sheet Al1050, deeper channels are formed than in materials STS304 and Ti-G5. Formed channel depth was increased when hardness of rubber pad was lower, thickness of rubber pad was high, and speed and pressure of punch were high. It was found the deepest channel was achieved when forming process condition was set with punch speed and pressure at 30 mm/s and 55 MPa, respectively using rubber pad having hardness Shore A 20 and thickness 60 mm. The channel depths of bipolar plates formed with Al1050, STS304 and Ti-G5 under the above process condition were 0.453, 0.307, and 0.270 mm, respectively. There were no defects such as wrinkle, distortion, and crack found from formed bipolar plates.

• Transactions of Materials Processing
• /
• v.11 no.6
• /
• pp.503-512
• /
• 2002

The drawbead is used to control material flow into the die during the binder wrap process and the stamping process in the sheet metal forming process. Since the dimension of drawbead is relatively small in comparison with the typical dimensions, it is difficult to include drawbeads in finite element analysis of the sheet metal forming process. It is because the mesh system has to be fine enough to describe the drawbead and the computation time is drastically increased. In this paper, simulation of drawbead forming has been carried out to obtain the equivalent boundary conditions in the binder wrap process and the stamping process. In order to investigate the effect of various die geometries, parameter studies are performed with the variation of parameters such as the blank length, the drawbead depth, the drawbead radius, the inclination of die and the friction coefficient.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1997.10a
• /
• pp.24-27
• /
• 1997

In the present work, rigid-plastic continuum elements employing the shape change and anisotropic effects are derived for the purpose of applying more realistic blankholding force condition in three-dimensional finite element analysis of sheet metal forming process. In order to incorporate the effect of shape change effectively in the derivation of finite element equation using continuum element for sheet metal forming, the convected coordinate system is introduced, rendering the analysis more rigorous and accurate. The formulation is extended to cover the orthotropic material using Hill's quadratic yield function. For the purpose of applying more realistic blankholding force condition, distributed normal and associated frictional tangent forces are employed in the blankholder, which is pressed normal and associated frictional tangent forces are employed in the blankholder, which is pressed against the flange until the resultant contact force with the blank reaches the prescribed value. As an example of sheet metal forming process coupling the effect of planar anisotropy and that of blankholding boundary condition, circular cup deep drawing has been analyzed considering both effects together.