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http://dx.doi.org/10.3795/KSME-A.2010.34.10.1507

Study on the Relationship Between Emission Signals and Weld Defect for In-Process Monitoring in CO2 Laser Welding of Zn-Coated Steel  

Kim, Jong-Do (Division Marine System Engineering, Korea Maritime Univ.)
Lee, Chang-Je (Graduate School, Korea Maritime Univ.)
Publication Information
Transactions of the Korean Society of Mechanical Engineers A / v.34, no.10, 2010 , pp. 1507-1512 More about this Journal
Abstract
In this study, the plasma induced by $CO_2$ laser lap welding of 6t Zn coated steel used for ship building was measured using photodiodes and a microphone. Then, the welding phenomenon with gap clearance of lap joint was compared with RMS-treated signal. Thus, we found that intensity of the RMS-treated signal increased with Zn vaporization; further, the presence of defects results in rapid variations with the RMS value as a function of lap-joint parameters. Besides, the FFT value of the raw signal with variations of changing welding parameters was calculated, and then the calculated FFT frequency value was set as the bandwidth of digital filter for a more accurate in-process monitoring. The RMS values were acquired by filtering the raw signal. By matching the weld beads and the calculated RMS values, we confirmed that there is a strong relationship between the signals and the defects.
Keywords
$CO_2$ Laser; Zn-coated Steel; Plasma Emission Signal; Weld Defect; FFT;
Citations & Related Records
Times Cited By KSCI : 3  (Citation Analysis)
Times Cited By SCOPUS : 0
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1 Katayama, S., Wu, Y. and Matsunawa, A., 2002, "Laser Weldability of Zinc-Coated Steels," ICALEO
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3 Kim, J. D. and Kim, Y. S., 2000, "The State of In-Process Quality Monitoring Technology in Laser Welding," Journal of KWJS, Vol. 18, No. 4, pp. 433-440.   과학기술학회마을
4 Kim, J. D. and Park, H. J., 2005,"The Weldability of $6mm^t$ Primer-coated Steel for Shipbuilding by $CO_2$ Laser(I)," Journal of KWJS, Vol. 23, No. 3, pp. 288-294.   과학기술학회마을
5 Park, H. J., Kim, J. D. and Kim, Y. S., 2003, "The Weldability of Primer-coated Steel for Shipbuilding by $CO_2$ Laser," Proc. KSME Spring, pp. 316-321.