• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 춘계학술발표대회 개요집
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• pp.68-70
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• 2002

A CCD camera with a laser strip was applied to realize the automation of welding process in GMAW. The Hough transformation was used to extract the laser stripe and to obtain specific weld points. In this study, a neural network based on the generalized delta rule algorithm was adapted for the process control of GMA, such as welding speed, arc voltage and wire feeding speed.

• Journal of Welding and Joining
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• 제11권1호
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• pp.52-61
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• 1993

Laser welding of ASTM no. 1060 Al plate with a pulsed Nd: YAG laser of 200W average power was performed for end capping of KMRR nuclear fuel elements In this research, we performed basic welding experiments. Firstly, laser output parameters which affect laser welding parameters were studied by changing laser input parameters for effective welding of 1060 Al plates. We found that laser power density and pulse energy are important parameters for smooth bead shape. Secondly, welding parameters which affect weld width-to-depth ratio were studied by changing power density and pulse energy, shielding gas, and defocusing. We found that power density must be higher than 0.3 Mw/cm$^{2}$ pulse energy must be higer than 3 J. travel speed must not exceed 200mm/sec, laser focus must be existed beneath 2-3mm from plate surface and helium is proper shielding gas. Thirdly, we studied the weld defects of Al-1060 such as crack and porosity in lap-joint welding. We designed new welding geometry for crack free welding of Al-1060 plates, and obtained crack free weldment but with lack of fusion. However, with Ti, Zr grain refiner elements, we can weld Al plates without solidification hot crack. Finally, we studied the origin of porosity by changing shielding gas. And we found that porosity was resulted from entrapment of shielding gas by the collapsing keyhole.

• 한국레이저가공학회지
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• 제2권3호
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• pp.11-18
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• 1999

This paper describes the weldability of carbon steel and stainless steel using 5㎾ $CO_2$ laser system with nearly multi-mode beam and a parabolic focusing mirror. In the laser welding of steels, major welding parameters are focal point, travel speed, beam power, shield gas and gap tolerance, etc.. Two kinds of gases(Ar, He) were used as a assist gas and supplied through the external nozzle. It is very important for optimum condition to remove plasma plume which absorbs laser beam and to obtain deep penetration and sound weld bead. Bead-on-plate welding tests were carried out for the experiments. Penetration data were obtained with various welding parameters and the effects of welding parameters were discussed. Butt welding tests were performed with various conditions. Only the optimum laser parameters assured good weld quality As a result of this study, We achieve the fundamental weldabilities using a high power $CO_2$ laser for carbon steel and stainless steel.

• 한국정밀공학회지
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• 제11권1호
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• pp.201-210
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• 1994

A theoretical heat-flow model incorporating with a constant moving CO$_{2}$ laser beam has been analyzed to predict depth and the shape of bead section during last beam welding. The laser beam is exponentially attenuated with an abosrption coefficient in the material. The solution can be expressed in terms of normalized variables. The experimental data were generated by usint CW 2 CO$_{2}$ laser with multi beam mode and CW 3 kW CO$_{2}$laser with Gaussian mode. The specimens were made as bead-on-plate welds for SM 10C, STS 304, STS 316, STS 420 and pure Nickel. The maximum possible penetration depth and the shape of beas section for given sources of laser power, travel speed and beam spot size can be prdicted with this model in a given material.

• Journal of Welding and Joining
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• 제34권5호
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• pp.26-32
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• 2016

In this study, Hot-wire laser welding (HWLW) without keyhole which deposits filler material by feeding hot wire into the process zone has been performed to increase process performance. From the analysis of High Speed Imaging (HSI), for higher voltage, the process is prone to arc formation and drop transfer, which is disagreeable transfer mode. It is necessary that arc formation and drop (globular) transfer should be avoided by lower voltage. Therefore, continuous wire melting and transfer mode is preferred when adopting this process. The HWLW technique has high potential in terms of performance, precision, robustness and controllability for thick section of narrow gap.

• Journal of Welding and Joining
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• 제29권1호
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• pp.107-114
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• 2011

CP steel was developed to reduce the weight and increase the strength of car body. When it was welded using state-of-the-art disk laser welding, the effected of boron on the microstructure and hardness were investigated. Welding power was fixed at 3.5kW and welding speeds were 4,8 and 12m/min. Full penetration occurred in welding speed of 12m/min and weld bead was almost unchanged with boron contents. But the welding speed increased, the upper and lower bead were narrowed. In a welding speed of more than 8m/min, underfill defects were formed on the bead bottom. The hardness of weld zone was somewhat fluctuation in fusion zone and HAZ showed the highest hardness values. The hardness of each region showed little change with the boron contents, and softening phenomenon occurred in the HAZ near the base metal regardless of the boron contents.

• 한국생산제조학회지
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• 제20권4호
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• pp.484-489
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• 2011

Nowadays, the automobile manufactures make a great efforts to reduce manufacturing cost, body weight and to develop eco-environmental parts in order to be more competitive and solve global warming. For these reasons, materials of automobile's parts are changed over from general carbon steel and stainless steel to plastic and Aluminum. And, laser welding technology is introduced to apply welding between aluminum parts. In this paper, the data of laser welding parameters is collected through lots of the experiment according to the material, welding speed and laser power to apply laser welding in Aluminum fuel filler neck assembly. After manufacturing prototype of aluminum fuel filler neck, vibration durability test, tensile strength test and salt water test are applied to verify product's satisfied function.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 2006년도 춘계학술발표대회 논문집
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• pp.35-40
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• 2006

Laser welding is high power density welding method which is higher speed and productivity, lower thermal deformation, without material restrictions for car body welding. But, in case of zinc coated sheet metal welding, the gap is needed $0.1{\sim}0.2mm$ to avoid weld bead blowup. This paper describe that it used dimple and pressure roller tool to improve laser welding quality for 3-layer zinc coated sheet metal.

• Journal of Advanced Marine Engineering and Technology
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• 제36권8호
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• pp.1076-1082
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• 2012

오늘날 LNG선의 용접에는 아크와 플라즈마가 사용되고 있으나 아크용접은 에너지 밀도가 낮아 후판에 대해서 다층용접이 불가피하며, 고밀도 열원인 레이저 용접에 비하여 용접속도에도 한계가 있다. 따라서 후판 용접시 다층용접에 의한 용접부의 조직적 결함이나 과대 입열로 형성된 열영향부 등의 문제를 해소하기 위하여 키홀용접에 의한 원패스 용접이 고려되고 있다. 키홀용접이 가능한 열원은 레이저, 전자빔, 플라즈마가 있으며, 현재 플라즈마 용접이 아크를 대체하여 LNG선 카고탱크의 멤브레인 용접에 적용되고 있다. 최근에는 멤브레인의 용접에 레이저를 적용하기 위한 많은 연구가 진행 중에 있다. 본 연구에서는 LNG선용 스테인리스강에 대한 파이버 레이저 및 플라즈마 아크 용접의 용접성, 기계적 성질 및 미세조직을 비교하였다. 그 결과 레이저 용접이 더 빠른 용접속도에서 좁은 용접부와 열영향부를 얻을 수 있었다. 따라서 LNG선의 용접에서는 파이버 레이저가 보다 우수한 용접법이라는 것을 알 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1302-1308
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• 2003

Welding characteristics of austienite 304 stainless steel and SM45C using a continuous wave Nd:YAG laser are experimentally investigated. Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. This paper describes the weld ability of SM45C carbon steel and austienite 304 stainless steel for machine structural use by Nd:YAG laser.