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대전류 고속 TIG 용접 특성에 미치는 He 혼합비의 영향
오동수,김영식,조상명,Oh Dong-Soo,Kim Yeong-Sik,Cho Sang-Myung 대한용접접합학회 2005 대한용접·접합학회지 Vol.23 No.3
Tungsten Inert Gas(TIG) welding is today one of the most popular arc welding process because of its high quality welds and low equipment costs. Even if welding productivity increases with welding speed and current, this strategy is limited by the appearance of defects such as undercut and humping bead due to the depressed molten metal. The purpose of this study investigates the effect of He mixing ratio on the characteristics with high current and speed in TIG welding. The conclusions obtained permit to explain the arc start characteristics quantitatively and the maximum welding speed on stable bead formation with He mixing ratio for high current and speed TIG welding observed in experiments. Also through the relation of the maximum arc pressure and surface depression depth at high current and speed TIG welding, it made clear the mechanism of unstable bead formation.
TIG 용접에서의 실드 가스 혼합비에 따른 아크 압력분포 특성
오동수,김영식,조상명,Oh Dong-Soo,Kim Yeong-Sik,Cho Sang-Myung 대한용접접합학회 2005 대한용접·접합학회지 Vol.23 No.1
Arc pressure is one of important factors in understanding physical arc phenomena. Especially it affects on the penetration, size and shape of TIG welding. Some researches were reported on the effect of arc pressure in low and middle current region. But there are not any research in high current region. The purpose of this study is to investigate the arc pressure distribution with mixing ratio of shield gas such as Ar and He gases. A Cu block with water cooling was specifically designed and used as an anode electrode in order to measure the arc pressure in high current region. Then, the arc pressure distribution was measured with change in welding current and mixing ratio of shield gases. The arc force was obtained by numerically integrating the measured results. As the results, it was shown that the arc pressure was concentrated at the central part of the arc in middle and high current regions when a pure Ar gas was used. In case of Ar + He mixing gas, the arc pressure was much lower than that of pure Ar gas. In addition, it was widely distributed to radial direction.
TIG 용접에서 열유속이 용융효율과 용입형상에 미치는 영향
오동수,조상명,Oh, Dong-Soo,Cho, Sang-Myung 대한용접접합학회 2009 대한용접·접합학회지 Vol.27 No.2
The characteristics of arc pressure, current density and heat flux distribution are important factors in understanding physical arc phenomena, which will have a marked effect on the penetration, size and shape of a weld in TIG welding. The purpose of this study is to find out the effect of the heat flux on the melting efficiency and penetration shape in TIG welding using the results of the previous investigators. The conclusions obtained permit to draw a proper method which derived the heat flux distributions by arc pressure distribution measurements, but previous researchers calculated heat flux and current distribution with the heat intensity measurements by the calorimetry. Heat flux of Ar gas arc was concentrated at the central part and distributed low from the arc axis to the radial direction, that of He mixing arc was lower than that of Ar gas, and it was wide distributed to radial direction. That showed a similar characteristic with the Nestor's by calorimetry calculated values. Throughout heat flux drawn in this study was discussed melting efficiency and penetration shape on Ar gas and He mixing gas arc.
[학술강연] MIG 용접에 의한 A1 합금의 필릿 용접 루트부 기공 발생 현상
오동수(Dong-Soo Oh),김영식(Yeong-Sik Kim),조상명(Sang-Myung Cho) 한국마린엔지니어링학회 2002 한국마린엔지니어링학회 학술대회 논문집 Vol.2002 No.-
In this study the porosity generation phenomena in fillet welding root of Al alloy by MIG welding were examined. The results are summarized as follows:<br/> A5052 AI alloys are subjected to certain type of weld defects by MIG welding, especially porosity and pit on root gap in fillet weldment. Porosity and pit were remarkably affected by root gap. Over 2.0mm of root gap in fillet weding is needed to consider a special counterplan.<br/>