• Journal of the Society of Naval Architects of Korea
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• v.38 no.2
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• pp.62-70
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• 2001

As the ship hull is a compound-curved structure, plate bending process is indispensible. The process includes press bending process for forming major 1st curvature and heating process for forming the rest curvature. Especially the heating process that is above 50 percents of entire bending work is carried out exclusively by skillful workers. Many researches have been made to automate the heating process but most of these are about line heating process and researches for triangle heating process are rare. This study is a fundamental study to develop a efficient analysis method for triangle heating and focused on clarifying the deformation characteristics of plate by triangle heating. In this paper, we carried out heating experiments and analysed the deformation characteristics of plate to explain the deformation characteristics of plates rationally by showing the phase transformed high temperature region. Also we investigated the heating effect on the hull material properties by mechanical tests.

• Journal of the Korean Ceramic Society
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• v.33 no.6
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• pp.660-664
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• 1996

We have studied the test method for strength of spray dried ceramic powder using manual press and UTM. which is one of the important to influence forming process. We could observe the compaction behavior using manual press. However the measurement of granule strength was only possible with UTM capable of providing the condition of a constant pressing rate. The strength of granule can be measured from the slope change of compaction curve and agrees with the value which is obtained from the combination of saturated tap density and compaction curve. So we proposed the accurate method to measure the strength of granule from the results of this study.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.349-350
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• 2006

PAM-STAMP is a widely used program which deals with press forming analysis. A blanking used in the press process depends on the experience of the workers. Thus it causes some waste material and demands a lot of time and many costs at the manufacturing mold. So we need to optimize of the blanking size. We have studied the optimal blanking size of the Brace Center Pillar using an Inverse module in PAM-STAMP

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1373-1378
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• 2007

Metal forming ins the process changing shapes and mechanical properties of the workpiece without initial material reduction through plastic deformation. Above all, because of hot working carried out above recrystallization temperature can be generated large deformation with one blow, it can produce with forging complicated parts or heat resisting super alloy such as Inconel 718 has the worst forgeability. In this paper, we established optimal variation of hot heading precess of the Inconel 718 used in heat resisting component and evaluated mechanical properties hot worked produce. Die material is SKD61 and initial temperature is $300^{\circ}C$. Initial billet temperature and punch velocity changed, relatively. Friction coefficient is 0.3 as lubricated condition of hot working. CAE is carried out suing DEFORM software before making the tryout part, and it is manufactured 150 ton screw press with optimal condition. It is known that forming load was decreased according to decreasing punch velocity.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.3
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• pp.55-58
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• 2008

Hydroforming is a forming technology in which a steel tube is set in a die and formed to fit a specified shape by applying hydraulic pressure from inside the tube while also applying force in the tube axial direction (axial feed). In present study, the entire design process chain for an automotive cross-member was simulated and developed using hydroforming technology on high-strength steel. The part design stage required a feasibility study. The process was designed using computer-aided design techniques to confirm the actual hydroformability of the part in detail. The possibility of using hydroformable cross-member parts was examined using cross-sectional analyses, which were essential to ensure the formability of the tube material for each forming step, including pre-bending and hydroforming. The die design stage included all the components of a prototyping tool. Press interference was investigated in terms of geometry and thinning.

• Transactions of Materials Processing
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• v.18 no.6
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• pp.488-493
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• 2009

The very big springback of advanced high strength steel(AHSS) sheets invokes undesired shape defects, which can be generally eliminated by die correction or process parameter control. The springback reduction by controlling the forming process parameters is easy for the application, but limited for the bulky achievement. In this study, the effective die correction method, which obtains the modification of tool shape from the relationship between die design variable and springback, is introduced and is applied to the TWB tool of automotive side rail to show the validity and usefulness. Among the die correction trials repeatedly performed, the first trial is carried out by correcting the tool shape to the opposite direction to the springbacks of several tool sections. Next trials are done by extrapolating the springbacks of among the original tool uncorrected and the tools corrected negative amounts of the springback and by finding tool shapes without springbacks. After the angle of side wall and radius of curvature of horizontal bottom floor are chosen as design variables in the tool design of side rail, the tool shape is corrected 3 times. The accuracy of final shape within the assembly limit of 1mm and the springback reduction of 75.8% compared to the uncorrected tool are achieved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.692-696
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• 2017

The shape of press components is becoming increasingly complex due to customer demands, process shortening and cost savings. In addition, the stability of the pressing process frequently varies during mass production due to the influence of many factors. In order to ensure the process stability, it is necessary to establish a process in which reproducibility is realized in tolerance, which is sufficient for advance study of shape, material, press, mold and lubrication. However, unforeseen changes in process parameters cause disruptions in production line shutdowns and production planning. In this paper, we introduce a method to monitor a real time process by applying a sensor to a press mold. A non-contact type sensor for measuring the flow of a sheet material and an example of an experiment using the optical sensor which is highly applicable to mass production are presented. An optical sensor was installed in a cylindrical drawing mold to test its potential application while changing the material, blank holder force, and drawing ratio. We also quantitatively determined that the flow of other sheet materials was quantified locally using a square drawing die and that the measured value was always smaller than the drawing depth due to the material elongation. Finally, we propose a field that can be used by attaching the sensor to the press mold. We hope that the consequent cost reduction will contribute to increasing global mold competitiveness.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.179-188
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• 2003

The objective of our study is to investigate the micro fabric ability by conventional metal forming processes. In the present investigation, micro hole punching was studied. We tried to control punching process at the micro level and scaled down the standard blanking condition for $25{\mu}m$ hole fabrication. To accommodate this, tungsten carbide tooling sets and micro punching press were carefully designed and assembled meeting accuracy requirements for $25{\mu}m$ hole punching. With our developments, 100, 50, and $25{\mu}m$ holes were successfully made on metal foils such as brass and stainless steel of 100, 50, and $25{\mu}m$ in thickness, respectively, and hole sizes and shapes were measured and analyzed to investigate fabrication accuracy. Shear behavior during micro punching was also discussed. Our study showed that the conventional punching process could produce high quality holes down to $25{\mu}m$.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.345-348
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• 2006

In sheet metal forming process using press and draw die some defect can be made because of the high pressure of air pocket between draw die and the product. The purpose of this study is to develop a program to decide an optimal combination of air vent hole size and number to prevent those defect on product. The air inside air pocket is considered as ideal gas and the compression and expansion is assumed as isentropic process. The mass flow is computed in two flow condition: unchocked and chocked condition. The present computation obtains required cross-sectional area of air vent hole for not exceeding the user specified pressure such as the pressure for yielding strength of the product or the pressure for unchocked flow. To validate the program the present results are compared with the results of other researchers and commercial CFD code.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.241-245
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• 2004

Among the various manufacturing processes of composites, the tape lay-up process of thermoset prepreg has many advantages compared to autoclave or hot press forming. It has a high potential to process automation and continuous fabrication .. Fiber placement developed as a logical combination of filament winding and automated tape placement to overcome some of the limitations of each manufacturing method. Fiber placement uses a compaction device to apply direct contact between the incoming materials in the fiber placement head and Heat is added to the materials at the nip point of the compaction roller. This paper will discuss property of thermoset composite as compaction and heat effect in Automated fiber placement