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주병돈(Byeong-Don Joo),이성문(Sung-Mun Lee),손영명(Young-Myung Son),문영훈(Young-Hoon Moon) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Hydroforming technology draws attentions of automotive industries due to its advantages such as weight reduction, increased strength, improved quality and reduced tooling cost. Hydroformed automotive parts used as structural components in vehicle 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. In this study, hydroforming process for the flanged tubular parts was proposed. Tube hydroforming experiments were conducted at various conditions. Forming characteristics at various pressure conditions were evaluated. With optimized condition flange was sucessfully formed. The results show that flanged automotive parts can be successfully produced with tube hydroforming.
주병돈(Byeong Don Joo),이혜경(Hyae Kyung Yi),장정환(Jeong Hwan Jang),권승오(Seung O Kwon),문영훈(Young Hoon Moon) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.6
Hydroforming is one of the useful processes in the automotive industry and recently for to improve the fuel efficiency, automotive industry focus on weight reduction. Aluminum alloys are light and has high structural rigidity, the need for hydroforming of aluminum alloy is increased. In this study, hydroformability and fracture criteria of FE analysis based on ductile fracture were investigated in warm hydro forming of Al 6061 tube and to evaluate the hydroformability, un i-axial tensile test and bulge test were performed at room temperature and 200℃. The measured flow stresses were used as input parameters for FE analysis, the damage values were calculated by FE analysis based on ductile fracture criteria at maximum radius of free bulged tubes, and damage values were compared of hexagonal shaped hydroformed parts.
김상윤(Sang Yun Kim),주병돈(Byeong Don Joo),전찬후(Chan Hu Jeon),문영훈(Young Hoon) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
Hydroforming is a technology that utilizes hydraulic pressure to form tube or sheet materials into desired shapes inside die cavities. Three-layered tube is assembled with inner, center and outer tube, similar in material or not and deforming simultaneously when internal pressure and axial feed were applied on the tube. Three-layered tube hydroforming is suitable to produce multiple tube joints which can be used in special applications such as automotive, aerospace, piping system and nuclear power plants. The precise control of internal pressure loading path in tube hydroforming process significantly affects on the final product quality. In this study, the effect of the loading path on forming characteristics in the tube hydroforming process is investigated. Free bulging tests were performed to study the expansion ability of the three tubes and tube hydroforming in a closed die was performed to investigate the hydroformability of the tubes. Hydroforming characteristics at various loading paths were analyzed and the loading path was optimized. The results show that final product of three-layered tube can be successfully fabricated by tube hydroforming process under optimized process parametes.
Fe-Cr계 금속 분말의 직접 레이저 용융을 통해 형성된 적층부 특성 분석
장정환 ( Jeong Hwan Jang ),주병돈 ( Byeong Don Joo ),전찬후 ( Chan Hu Jeon ),문영훈 ( Young Hoon Moon ) 대한금속재료학회 ( 구 대한금속학회 ) 2012 대한금속·재료학회지 Vol.50 No.2
Direct laser melting (DLM) is a powder-based additive manufacturing process to produce parts by layer-by-layer laser melting. As the properties of the manufactured parts depend strongly on the deposited laser-melted bead, deposited layers obtained by the DLM process were characterized in this study. This investigation used a 200 W fiber laser to produce single-line beads under a variety of different energy distributions. In order to obtain a feasible range for the two main process parameters (i.e. laser power and scan rate), bead shapes of single track deposition were intensively investigated. The effects of the processing parameters, such as powder layer thickness and scan spacing, on geometries of the deposited layers have also been analyzed. As a result, minimum energy criteria that can achieve a complete melting have been suggested at the given powder layer thickness. The surface roughnesses of the deposited beads were strongly dependent on the overlap ratio of adjacent beads and on the energy distributions of laser power. Through microstructural analysis and hardness measurement, the morphological and mechanical properties of the deposited layers at various overlapped beads have also been characterized.
레이저 직접금속성형기술을 이용한 금형재 표면보수 특성 연구
손영명(Young-Myung Son),장정환(Jeong-Hwan Jang),주병돈(Byeong-Don Joo),임홍섭(Hong-Sup Yim),문영훈(Young-Hoon Moon) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.7
Direct laser metal forming technology was applied to restore the damaged mold surface. In order to estimate melting characteristics of the 20 ㎛ Fe-Cr-Ni powder, single layer experiments were performed at various levels of heat input. The process window of the 20 ㎛ Fe-Cr-Ni powder provided feasible process parameters for the smooth regular surface. The cross hatching scanning strategy on the multiple layer experiment was performed to reduce the thickness non-uniformity of edge portions compared with the one direction scanning. To estimate the coherence between the melted powder and the basematal, the tendency of hardness distribution has been observed. The hardness of the melted and the remelted zone was distributed from 400HV to 600HV. It is over 2 times compared of the hardness of the basemetal. Experimental results show that the mold restoring process using direct laser metal forming can be successfully applied in the mold repair industry.
김수희(Su Hee Kim),전찬후(Chan Hu Jeon),주병돈(Byeong Don Joo),김윤규(Yun Gyu Kim),문영훈(Young Hoon Moon) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5
Double layered tube is assembled with an inner tube and outer tube contacting closely and deforming simultaneously when subjected to external force. For the manufacturing of double layered tube, the hydroforming assembly technology has several advantages. Therefore in this study, hydroforming characteristics of double layered tube was investigated. The X-ray CT measurement and penetration test were performed to measure double layer tube’s gap between inner and outer tube at various hydroforming pressure. The connection force measurement was also performed to estimate the load for characterization of double layered tube.