Abstract
In this study, induced plasma that is created during the CO2 laser lap welding of 6-mm-thick Zn coated steel for shipbuilding were measured through photo-diode and microphone. Then, we compared and analyzed the RMS value of plasma emission signal and spatter generation amount as a function of lap clearances with Zn coated thickness. The results indicated that as RMS values increased depending on the amount of Zn vaporization, and RMS also changed abruptly when defects occurred depending on lap joint conditions. Also, as a result of obtaining FFT value of raw signal by welding conditions, the obtained frequency signal was about 30 Hz at coating thickness 15 μm and about 50 Hz at coating thickness 30 μm in light signal, and in acoustic signal, peak value appeared at about 1 kHz. In addition, it was found that when the frequency value was set as the bandwidth of bandpass-filter, and the RMS values which were obtained after filtering raw signals were matched to weld bead. Thus we have considered that the signals and defects were very closely related.
Similar content being viewed by others
Abbreviations
- D P :
-
penetration depth of weldment
- Gc:
-
gap clearance between lap joint
- f d :
-
defocused distance
- P :
-
laser power
- v :
-
welding speed
- W b :
-
bead width of weldment
References
Kim, J. D. and Kim, Y. S., “The State of In-Process Quality Monitoring Technology in Laser Welding,” Journal of Korean Welding and Joining Society, Vol. 18, No. 4, pp. 433–440, 2000.
Steen, W., “Laser Material Processing,” Springer, 3rd Ed., pp. 351–382, 2003.
Kim, J. D., “Fundamental Study on the Weld Defects and Its Realtime Monitoring Method,” Journal of the Korean Welding Society, Vol. 20, No. 1, pp. 26–33, 2002.
Chen, H. B., Li, L., Brookfield, D. J., and Williams, K., “Laser Process Monitoring with Dual Wavelength Optical Sensors,” Proc. of ICALEO, pp. 113–122, 1991.
Kim, J. D., Tae, G. B., Lee, C. H., Kwag, M. S., and Oh, J. S., “A Study on Shield Gas Behavior by Flow Visualization in Laser Welding,” Proc. of KOSME Conference, pp. 37–38, 2007.
Kim, J. D., Yoon, H. J., Lee, C. H., and Kil, B. L., “A Study on Cast Basalt Encased Pipe for Prolong the Life of Pipeline in a Vessel,” Proc. of KOSME Conference, pp. 275–276, 2007.
Kim, J. D., Lee, C. H., and Kim, Y. S., “The Weldability of Non-Oriented Electric Steel for Laminated Stator Cores by Nd:YAG Laser,” Proc. of KSME Conferencs, pp. 35–40, 2007.
Beyer, E., Gasser, A., Gatzweiler, W., and Sokolowski, W., “Plasma Fluctuations in Laser Welding with CW-CO2 Lasers,” Proc. of ICALEO, pp. 17–23, 1987.
Kamimuki, K., Inoue, T., Yasuda, K., Muro, M., Nakabayashi, T., and Matsunawa, A., “Development of A Monitoring Method in YAG Laser Welding A Study of the Monitoring for YAG Laser Welding (Report 1),” Quarterly Journal of the Japan Welding Society, Vol. 19, No. 3, pp. 457–464, 2001.
Kamimuki, K., Inoue, T., Yasuda, K., Muro, M., Nakabayashi, T., and Matsunawa, A., “Behavior of Monitoring Signals at the Weld Defect Part in YAG Laser Welding. A Study of the Monitoring for YAG Laser Welding. (Report 2),” Quarterly Journal of the Japan Welding Society, Vol. 20, No. 3, pp. 369–377, 2002.
Sokolowski, W., Herziger, G., and Beyer, E., “Spectral Plasma Diagnostics in Welding with CO2 Lasers,” Proc. of SPIE, Vol. 1020, pp. 96–102, 1989.
Garzweiler, W., Maischner, D., and Beyer, E., “On-Line Plasma Diagnostics for Process-Control in Welding with CO2 Lasers,” Proc. of SPIE, Vol. 1020, pp. 142–148, 1989.
Katayama, S., Wu, Y., and Matsunawa, A., “Laser Weldability of Zinc-Coated Steels,” Proc. of ICALEO, pp. 528–536, 2001.
Kim, J. D. and Park, H. J., “The Weldability of 6mmt Primer-Coated Steel for Shipbuilding by CO2 Laser (I),” Journal of Korean Welding and Joining Society, Vol. 23, No. 3, pp. 76–82, 2005.
Park, H. J., Kim, J. D., and Kim, Y. S., “The Weldability of Primer-Coated Steel for Shipbuilding by CO2 Laser,” Proc. of KSME Spring Conference, pp. 316–321, 2003.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Lee, CJ., Kim, JD. & Kim, YC. Study on monitoring of plasma emission signal in lap welding of Zn coated steel sheet using CO2 laser. Int. J. Precis. Eng. Manuf. 16, 495–500 (2015). https://doi.org/10.1007/s12541-015-0067-4
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12541-015-0067-4