• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1995년도 춘계학술대회논문집
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• pp.19-30
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• 1995

The analysis had been already completed to detect forming defects for the forming processes of C/R bearing rings. But some unpredicted problems were found through the experiments. So expert redesigned new forming processes to prevent the problems and new analysis was began according to the new processes to find faults for the processes. The forming processes consist of 1 for the outer ring. 6 inner ring. The thickness of metal sheet used is changed to 1.5mm from 1.6mm. Elasto-plastric finite element method is applied to involve the effect of spring back . The most representative alteration is forming of two predents to assist later forming . Thining and distribution of high residual stress are derived from the results of simulations. It is confirmed that the industry expert agree the possiblilty of defects dervied from the new FEM results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.15-18
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• 1997

The plane strain stretch test (PSST) developed by POSCO as an activity of customer service was applied to the establishment of the formability criteria and the prediction of failure during the stamping processes. The PSST was applied to the actual parts such as oil pan and shock mount and the criteria of PSST value for each forming parts were established. These value can provide the possibility of prediction of failure before the stamping process. These results show that the PSST can precisely predict the stamping formability of steel sheets.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.529-533
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• 2008

Thick pipes have been used in fields of ocean and industrial plants, and pipe arrangement of oil and water pipelines. Mostly, roll bending process has been used in manufacture of the pipes. Recently, however, studies on the pipe forming processes using brake press have been performed. Normally, the brake press has high aspect ratio, so structural integrity evaluation should be conducted. In this study, finite element analysis of structural integrity for the brake bending press was carried out for thick pipe forming process.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.39.2-39.2
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• 2010

Recently, hot stamping process has been paid attention greatly by automobile makers in accordance with the fuel efficiency and environmental issues as well as crash safety issue. The hot-stamped parts, however, demand extreme mechanical properties such as tensile strength of over 1470 MPa or equivalently Vickers hardness of around 450. In this work, to meet the demand efficiently, a method to predict mechanical property of hot-stamped parts based on numerical phase transformation scheme has been proposed associated with the thermo-mechanical coupled finite element analysis. This work deals with various phase transformation equations and validates them to select appropriate model for 0.2C-0.1Si-1.4Mn-0.5Cr-0.01Mo-0.002B steel sheet. The authors show that an efficient method saving time and cost to develop hot-stamped automobile parts ensuring suitable mechanical properties such as Vickers hardness and strength.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 금형가공 심포지엄
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• pp.8-18
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• 1998

The effect of press warm forming in cylindrical deep drawing of stainless-aluminum clad sheet metals are examined . The temperature of die and blank holder is varied from room temperature to 20$0^{\circ}C$, while the punch is kept cooled during test to increase the fracture strength of workpiece on the punch corner area. Test materials chosen for experiments are STS304-Al050-STS304, STS304-A1050-STS430-, STS304 and Al050 metals and teflon film as a lubricant is used on both sides of a workpiece. The limit drawing ration as well as quality of drawn cups (distribution of thickness and hardness)are investigated and discussed.

• 소성∙가공
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• 제17권4호
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• pp.263-271
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• 2008

Process design is carried out for a press forming of a CTBA in the rear suspension assembly based on the result of the finite element analysis. The analysis simulates the two-stage stamping process with the initial design and it fully reveals the unfavorable mechanism which develops inferiorities during forming. In this paper, a new design guideline is proposed to modify the process and tool shapes for a single-stage forming process. With the improved tool design, prototypes are fabricated after several try-out processes. Results of the durability tests show that the design requirement of the part is satisfied and the effective weight reduction is achieved.

• 소성∙가공
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• 제26권6호
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• pp.372-377
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• 2017

In this paper, an effective design procedure was proposed to design the rib of die structure for auto-body member with ultra-high strength steel (UHSS) having ultimate tensile strength (UTS) of 1.5 GPa. From analysis results of the die structure, structural safety of the die was evaluated with information such as displacement and von-Mises stress. It was concluded that the casting part could be designed in order to reduce tool deformation. A design guideline of the die structure was proposed, especially for the rib structure in the casting part with an optimization scheme and local reinforcement concept. Simulation result following the design guideline fully explained that stability of the tool structure could be obtained simultaneously with weight minimization.

• Design & Manufacturing
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• 제2권4호
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• pp.11-15
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• 2008

In the sheet metal forming using a high speed press machine, driving device, such as crank, link, and knuckle mechanism, has to be designed in consideration of impact at a moment when press die contact with material, because the impact affects a dimensional accuracy of products and a life span of press die. In this study, dynamic analysis was performed using numerical simulation in order to verify the impact reduction effect for proposed double knuckle mechanism by estimating rolling and pitching moment of slide.

• 한국정밀공학회지
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• 제25권7호
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• pp.64-71
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• 2008

Burr generated on plate holder should be removed through additional process, because it has an influence on the function of automotive seat recliner. The process layout to perform simultaneously embossing and half blanking of plate holder has been developed in this study in order to minimize the influence of burr formation. The optimal process condition to satisfy the required dimensional accuracy of plate holder has been determined using Taguchi method and finite element analysis. It has been shown from experimental results that the proposed method is decidedly superior to the previous FCF method from the aspect of sheared surface, roll-over, flatness and burr height.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.450-453
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• 2009

In order to overcome drawbacks of the advanced high strength steel such as inferior formability and large springback, the hot press forming process(HPF) has been being applied for forming of automotive sheet parts. Good formability and dimensional accuracy without springback as well as good crash performance of final products are the advantages of the HPF process. In this work, a method to characterize the mechanical properties of the HPF steel was developed based on the simple tension test at high temperatures and its finite element analysis, while it was applied to obtain strain rate and temperature dependent flow curves of the HPF steel. The final flow curves were represented by utilizing the Johnson-Cook type equation both in uniform and post-uniform deformation regions.