• 대한기계학회논문집A
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• 제30권4호
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• pp.428-434
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• 2006

Pulse laser welding of AISI 304 stainless steel plate was simulated to find optimal welding conditions by using commercial finite element code MARC. Due to geometric symmetry, a half model of AISI 304 stainless steel plate was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat, mass density and latent heat were given as a function of temperature. A moving heat source was designed on the basis of experimental data. As a result, Nd:YAG laser welding for AISI 304 stainless steel was successfully simulated and it should be useful to determine optimal welding condition.

• 대한기계학회논문집B
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• 제28권10호
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• pp.1202-1209
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• 2004

In this study, numerical investigation has been performed on the evolution of weld pool geometry with moving free surface during low-energy density laser welding process. The free surface elevates near the weld pool edge and descends at the center of the weld pool if d$\sigma$/dT is dominantly negative. It is shown that the predicted weld pool width and depth with moving free surface are a little greater than those with flat weld pool surface. It is also believed that the weld pool surface oscillation during the melting process augments convective heat transfer rate in the weld pool. The present analysis with moving free surface should be considered when We number is very small compared to 1.0 since the deformation of the weld pool surface is noticeable as We number decreases.

• 대한기계학회논문집
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• 제19권4호
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• pp.908-917
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• 1995

The constant .DELTA.K fatigue tests are performed in SS41 and its weldments to investigate crack opening behavior and fatigue crack propagation behavior at each parts of weldment and its boundary layer. The weldments were annealed after welding for the purpose of relieving residual stress. Every weldments has notch at weld metal zone, and fatigue crack propagates from weld metal zone to vase metal zone perpendicular to weld line. The Laser ISDG method is used in order to determine the crack opening ratio, this method is more precise than indirect measurement method, and faster and easier than other direct measurement method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1190-1195
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• 2004

In this study, numerical investigation has been performed on the evolution of key-hole geometry during high-energy density laser welding process. Unsteady phase-change heat transfer and fluid flow with the surface tension and recoil pressure are simulated. To model the overheated surface temperature and recoil pressure considering subsonic/sonic vapor flow, the one-dimensional vaporization models proposed by Ganesh and Knight are coupled over liquid-vapor interface. It is shown that the present model predicts well both the vaporization physics and the fluid flow in the thin liquid layer over the other model.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.203-208
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• 2004

The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. Welding characteristics of Inconel 600 Alloy using a continuous wave Nd:YAG laser are experimentally investigated. The major process parameters studied in the present laser welding experiment were position of focus, laser power, travel speed. The gap and offset maintained as small as possible. Optical microscope were used to investigate the microstructures of the welded zone. The follow conclusions can be drawn the laser power and travel speed have a pronounced effect the fusion zone size and shape.

• 한국공작기계학회논문집
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• 제13권3호
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• pp.119-125
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• 2004

Generally, it is used the compensation spring to compensate the inaccuracy of screen image induced by thermal deformation in CRT monitor. Its mechanism is bi-metallic system made of heterogeneous metals and these is bonded by laser welding. But laser welding induces the non-uniform temperature distribution and locally residual stress is yielded by these temperature deviation. This paper studies residual stress of laser weldment using FEA and hole drilling method. The results are followed. In the case of heterogeneous materials weldment, higher residual stress induced in the weldment region of SUS 304 which have larger CTE than Ni 36 and residual stress on the middle of specimen is higher by 10.9% than that of its surface Measured residual stress of SUS 304 yield 481MPa and that of Ni 36 is 140.5MPa in the vicinity of the welding region. And the residual distribution is very similar in comparison with FEA result.

• 대한기계학회논문집B
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• 제29권10호
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• pp.1111-1118
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• 2005

In this study, a unified numerical investigation has been performed on the evolution of weld pool and key-hole geometry during low-power and high-power density laser welding. Unsteady phase-change heat transfer and fluid flow with the surface tension are examined. The one-dimensional vaporization model is introduced to model the overheated surface temperature and recoil pressure during high-power density laser welding. It is shown that Marangoni convection in the weld pool is dominant at low-power density laser welding, and the keyhole with thin liquid layer and the hump are visible at high-power density laser welding. It is also shown that the transition from conduction welding to penetration welding fur iron plate exists when the laser power density is about $10^6W/Cm^2$.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.169-172
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• 2002

A vision sensor measure range data using laser light source. This sensor generally use patterned laser which shaped single line. But this vision sensor cannot satisfy new trend which feeds foster and more precise processing. The sensor's sampling rate increases as reduced image processing time. However, the sampling rate can not over 30fps, because a camera has mechanical sampling limit. If we use multi line laser pattern, we will measure multi range data in one image. In the case of using same sampling rate camera, number of 2D range data profile in one second is directly proportional to laser line's number. For example, the vision sensor using 5 laser lines can sample 150 profiles per second in best condition.

• 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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.125-128
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• 1995

The remote sleeve repair-welding technology using the pulsed Nd:YAG laser for increasing the lifetime of the steam generator tube in the nuclear power plant has been developed. The laser welding has many advantages on deep penetration depth and narrow heat affect zone(HAZ). The inconel 600 tube and inconel 690 sleeve used high temperature and high pressure service have been welded as round lap welds. It is found that the relation between the connection width and welding parameters. It is found that the shear strength in proportion to the connection width by conducting tensile-shear tests.