• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.44-49
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• 2001

Tube hydroforming is a relatively new technology in comparison with conventional stamping process. Thus, there is no large knowledge base to assist the product and process designers, especially from the friction point of view. This paper covers the topic f friction and lubrication with regard to tube hydroforming. It presents the fact that frictional characteristic can have an effect on the formability of specific components. It also presents the results of test about several lubricants which are used in practical press process. The presented concept describes the equipment which is required to determine the friction coefficient.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.317-317
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• 2009

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.54-57
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• 2001

Hydroforming is core production techniques for the super light weight and high safety of the vehicle body. In order to establish and understand hydroforming, the tube hydroforming simulator which could control an axial compression and high internal pressure with computer operation was developed in tube bulging. This paper presents experimental investigation for process parameters, such as Internal pressure and axial compression. In addition, the mechanical properties, such as strain hardening and energy absorption ability of hydroformed part, is discussed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.210-213
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• 2004

Based on plastic instability, analytical prediction of bursting failure on tube hydroforming processes under combined internal pressure and independent axial feeding is carried out. Bursting is irrecoverable phenomenon due to local instability under excessive tensile stresses. In order to predict the bursting failure, three different classical necking criteria such as diffuse necking criterion for sheet and tube, local necking criterion for sheet are introduced. The incremental theory of plasticity fur anisotropic material is adopted and then the hydroforming limit and bursting failure diagram with respect to axial feeding and hydraulic pressure are presented. In addition, the influences of the material properties such as anisotropy parameter, strain hardening exponent on bursting pressure are investigated. As results of the above approach, the hydroforming limit in view of bursting failure is verified with experimental results.

• 소성∙가공
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• 제19권1호
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• pp.32-37
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• 2010

Hydroforming has attracted a great deal of attention in the manufacturing industries for vehicles and transportation systems. Hydroforming technology contributes to weight reduction, increased strength, improved quality and reduced tooling cost. Hydroformed automotive parts used as structure components in vehichle body frame often have to be structurally joined at some point. Therefore it is useful if the hydroformed automotive parts can be given a localized attachment flange. For a given flange shape, a parting plane for the dies is established relative to which the various surfaces of the flange shape, in cross section, have no significant reverse curvature. In this study, hydroforming process for flange forming was proposed. FE analysis to form flanged circular shape and flanged rectangular shape was preformed with Dynaform 5.5. To accomplish successful hydroforming process design, thorough investigation on proper combination of process parameters such as tool geometry and hydraulic pressure has been performed and optimized. The results show that flanged automotive parts can be successfully produced with tube hydroforming.

• 소성∙가공
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• 제16권3호
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• pp.201-209
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• 2007

Generally, the forming process of suspension system parts have been considered only considered with the formability and have not been considered with the durability of suspension system. But the durability of suspension system is very important characteristic for the dynamic performance of vehicle. Therefore, the suspension system should be manufactured to consider the durability as well as the formability. This paper is about an optimum forming process design with the effect of section properties to consider the roll durability of torsion beam type suspension. In order to determine the tube hydroforming process for the satisfaction the roll durability, the stamping and hydroforming simulation by finite element method were performed. And the results from finite element analysis and roll durability examination showed the tube hydroforming process of torsion beam is optimized as satisfying the durability performance.

• 소성∙가공
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• 제15권2호
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• pp.138-142
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• 2006

A tube hydroformability testing system was designed and manufactured to observe the forming steps and to provide arbitrary combination of internal pressure and axial fred. The forming limit diagram of an aluminum tube was obtained from the free bulge test and the T-shape forming test using this system, giving the criteria for predicting failure in the hydroforming process. The hydroformability of aluminum tube according to different conditions of a prebending process was discussed, based on the finite element analysis and the forming limit test. The effects of 2D and 3D pretending on the tube hydroforming process of an automotive trailing arm were evaluated and compared with each other.

• 소성∙가공
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• 제22권5호
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• pp.275-279
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• 2013

The tube hydroforming process has received much attention in the automotive industry because of its advantages compared to conventional manufacturing technologies. A wide range of products such as sub-frames, camshafts, radiator frames, axles and crankshafts are made by hydroforming process. The hydroformed parts often need to be structurally joined to other components during assembly. Therefore, these automotive parts need to be manufactured with a localized attachment flange. In this study, FE forming analyses of a part with a rectangular flanged shape was performed with Dynaform 5.5. Using the optimized conditions determined numerically, hydroforming experiments were performed. Then, the characterization of defects was analyzed. Finally, the accuracy of the optimized internal pressure condition as well as that of the initial ram position were evaluated. The results demonstrated that flanged parts can be successfully produced using the tube hydroforming process.

• 소성∙가공
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• 제9권6호
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• pp.561-566
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• 2000

Recently, the hydroforming technology has been recognized as a general technique in manufacturing industry, especially in automotive industry. Hydroforming is applied to increase strength, and to decrease weight, cost and parts. Hydroforming is based on the inflation of, for Instance, a tube, coupled with axial or radial compression and by subsequent expansion and sizing against the die wall. Expansion, axial feeding, calibration are important parameters in this process. In this paper, the effects of various parameters such as internal pressure, axial feeding and friction on hydroforming of automotive bumper rail have been considered.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.318-321
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• 2006

In this strudy, the free-bulge test and FE analysis have been used to define the fracture criteria based on the cockroft and Latham's criterion in warm hydroforming of Al 6061 tube. Full annealing and T6 treatment for heat treatment of Al 6061 tube ware used in this study. As-extruded, full annealed and T6-treated Al 6061 seamless tubes were prepared. To evaluate the hydroformability, uni-axial tensile test and bulge test were performed between room temperature and $200^{\circ}C$. And measured flow stress was used to simulate the warm hydroforming. A commercial FEM code, DEFORM-$2D^{TM}$, was used to calculate the damage value. A forming limit based ductile fracture criteria has been proposed by the results of experimental and FE analysis. The calculated values for fracture criteria will be efficient to predict the forming limit in hydroforming for real complex shaped part.