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

아연코팅 강판의 CO2 레이저용접시 인프로세스 모니터링을 위한 측정신호와 용접결함과의 관련성 연구

  • 김종도 (한국해양대학교 기관시스템공학부) ;
  • 이창제 (한국해양대학교 대학원)
  • Received : 2010.05.19
  • Accepted : 2010.07.30
  • Published : 2010.10.01


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.


Supported by : 정보통신진흥원


  1. Katayama, S., Wu, Y. and Matsunawa, A., 2002, "Laser Weldability of Zinc-Coated Steels," ICALEO
  2. Kim, J. D. and Lee, C. J., 2009, "A Study on Characteristics of Plasma Emission Signals with Welding Conditions in $CO_2$ Laser," Journal of KSME(A), Vol. 33, No. 11, pp. 1256-1261.
  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.
  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.
  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.