• Proceedings of the KSME Conference
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• 2003.04a
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• pp.316-321
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• 2003

The spatter and porosity could be occurred during $CO_2$ CW laser welding of Primer-coated Steel for Shipbuilding. This study has suggested an alternative idea by examining of weld-defect formation mechanism. The primer-coated plate has caused the spatter, humping bead and porosity and these are main part of the welding defect, attributed to the powerful vaporizing pressure of primer attached on the base metal. The zinc of primer has a boiling point that is the lower temperature than melting point of steel. Zinc va}X)f will build up at the interface between the two sheets and this tends to deteriorate the quality of the weld by ejecting weld material from lap position or leaving porosity. Therefore introducing a small gap clearance in the lap position, the zinc vapor could escape through it and sound weld beads can be acquired. In conclusion, we suggested the occurred and prevented mechanism of weld defects with searching the factor.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.1
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• pp.109-115
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• 2004

The spatter and porosity could be occurred during$CO_2$CW laser welding of Primer- coated steel for shipbuilding. This study has suggested an alternative idea by examining of weld-defect formation mechanism. The primer-coated plate induced the spatter humping bead and porosity and these are main part of the welding defect. attributed to the powerful vaporizing pressure of primer attached on the base metal The zinc of Primer has a boiling point that is the lower temperature than melting point of steel zinc vapor will build up at the interface between the two sheets and this tends to deteriorate the quality of the weld by ejecting weld material from lap position or leaving porosity. Therefore introducing a small gap clearance in the lap position. the zinc vapor could escape through it and sound weld beads can be acquired. In conclusion, we suggested the occurred and prevented mechanism of weld defects with searching the factor.

• Journal of Welding and Joining
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• v.24 no.2
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• pp.71-78
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• 2006

It has been reported that good quality weld beads are not easily obtained during the $CO_2$ CW laser welding of primer coated plate. However, by introducing a small gap clearance in the lap position, the zinc vapor can escape through it and sound weld beads can be acquired. Therefore, this study examines for keyhole behavior by observing the laser-induced plasma and investigates the relation between keyhole behavior and formation of weld defect. Laser-induced plasma has accompanied with the vaporizing pressure of zinc ejecting from keyhole to surface of primer coated plate. This dynamic behavior of plasma was very unstable and this instability was closely related to the unstable motion of keyhole during laser welding. As a result of observing the composition of porosity, much of Zn element was found from inner surface of porosity. But Zn was not found from the dimple structure fractured at the weld metal. By analyzing of vaporizing element in laser welding, a component ratio of Zn was decreased by introducing a small gap clearance. Therefore we can prove that the major cause of porosity is the vaporization of primer in lap position. Mechanism of porosity-formation is that the primer vaporized from the lap position accelerates dynamic behavior of the key hole and the bubble separated from the key hole is trapped in the solidification boundary and romaines as porosity.

• International Journal of Korean Welding Society
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• v.4 no.1
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• pp.30-37
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• 2004

There have been continuous efforts on automating welding processes. This automation process could be said to fall into two categories, weld seam tracking and weld quality evaluation. Recently, the attempts to achieve these two functions simultaneously are on the increase. For the study presented in this paper, a vision sensor is made, a vision system is constructed and using this, the 3 dimensional geometry of the bead is measured on-line. For the application as in welding, which is the characteristic of nonlinear process, a fuzzy controller is designed. And with this, an adaptive control system is proposed which acquires the bead height and the coordinates of the point on the bead along the horizontal fillet joint, performs seam tracking with those data, and also at the same time, controls the bead geometry to a uniform shape. A communication system, which enables the communication with the industrial robot, is designed to control the bead geometry and to track the weld seam. Experiments are made with varied offset angles from the pre-taught weld path, and they showed the adaptive system works favorable results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.6
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• pp.8-14
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• 2022

In this study reports experiments were conducted to determine the quality of weld beads of different materials, Al and Cu. Among the lasers used to make battery cells for electric vehicles, non-destructive testing was performed using deep learning to determine the quality of beads welded with the ARM laser. Deep learning was performed using AlexNet algorithm with a convolutional neural network structure. The results of quality identification were divided into good and bad, and the result value was derived that all the results were in agreement with 94% or more. Overall, the best welding quality was obtained in the experiment for the fixed ring beam output/variable center beam output, in the case of the fixed beam (ring beam) 500W and variable beam (center beam) 1,050W; weld bead failure was seldom observed. The tensile force test to confirm the reliability of welding reported an average tensile force of 2.5kgf/mm or more in all sections.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2000.06a
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• pp.55-60
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• 2000

Laser welding is an important technology in the assembly of automotive. In this paper, Nd:YAG laser welding of applications for auto body assembly will be introduced. This paper will describe characteristics of the CW Nd:YAG laser lap-joint welding, and laser welding of specific configurations for a Zinc-coated steel. Experimental results indicated that the weld quality of auto body assembly using the CW Nd:YAG laser welding technology.

• Proceedings of the KWS Conference
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• 2000.04a
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• pp.307-309
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• 2000

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.274-276
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• 2000

• Journal of Welding and Joining
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• v.18 no.2
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• pp.170-170
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• 2000

• Journal of Welding and Joining
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• v.18 no.2
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• pp.43-48
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• 2000