Plasma Plume Oscillations Monitoring during Laser Welding of Stainless Steel by Discrete Wavelet Transform Application

The plasma optical radiation emitted during CO2 laser welding of stainless steel samples has been detected with a Si-PIN photodiode and analyzed under different process conditions. The discrete wavelet transform (DWT) has been used to decompose the optical signal into various discrete series of sequences over different frequency bands. The results show that changes of the process settings may yield different signal features in the range of frequencies between 200 Hz and 30 kHz. Potential applications of this method to monitor in real time the laser welding processes are also discussed.

[1]  Peng Zhao,et al.  Quality assessment of aluminum alloy resistance spot welding based on wavelet and statistic analysis , 2009, 2009 International Conference on Information and Automation.

[2]  Amara Lynn Graps,et al.  An introduction to wavelets , 1995 .

[3]  Antonio Ancona,et al.  A Real-Time Spectroscopic Sensor for Monitoring Laser Welding Processes , 2009, Sensors.

[4]  Isamu Miyamoto,et al.  Characterizing keyhole plasma light emission and plasma plume scattering for monitoring 20 kW class CO2 laser welding processes , 2002 .

[5]  J. Jones,et al.  Optical techniques for real-time penetration monitoring for laser welding. , 2005, Applied optics.

[6]  John Dowden,et al.  Theory of the oscillations of an ellipsoidal weld pool in laser welding , 1991 .

[7]  Pietro Mario Lugarà,et al.  Real-time monitoring of laser welding by correlation analysis: The case of AA5083 , 2007 .

[8]  Eckhard Beyer,et al.  On-Line Plasma Diagnostics For Process-Control In Welding With CO2 Lasers , 1989, Other Conferences.

[9]  Martin Vicanek,et al.  Oscillations of the keyhole in penetration laser beam welding , 1994 .

[10]  Ajit S. Bopardikar,et al.  Wavelet transforms - introduction to theory and applications , 1998 .

[11]  Radovan Kovacevic,et al.  Wavelet transform analysis of acoustic emission in monitoring friction stir welding of 6061 aluminum , 2003 .

[12]  M Vicanek,et al.  Forced oscillations of the keyhole in penetration laser beam welding , 1996 .

[13]  H. Zeng,et al.  Wavelet analysis of acoustic emission signals and quality control in laser welding , 2001 .

[14]  Pietro Mario Lugarà,et al.  Correlation spectroscopy as a tool for detecting losses of ligand elements in laser welding of aluminium alloys , 2006 .

[15]  Hao Zeng,et al.  Application of artificial neural network in laser welding defect diagnosis , 2005 .

[16]  Phiroze Kapadia,et al.  Capillary waves on the weld pool in penetration welding with a laser , 1989 .

[17]  Pietro Mario Lugarà,et al.  Correlation analysis in laser welding plasma , 2005 .

[18]  P. M. Lugarà,et al.  Optical Sensor for real-time Monitoring of CO(2) Laser Welding Process. , 2001, Applied optics.

[19]  Pietro Mario Lugarà,et al.  A study of the shielding gas influence on the laser beam welding of AA5083 aluminium alloys by in-process spectroscopic investigation , 2006 .

[20]  M. Vicanek,et al.  Dynamic behaviour of the keyhole in laser welding , 1993 .

[21]  A. Ancona,et al.  11 – Monitoring laser welding , 2008 .

[22]  H. S. Wolff,et al.  iRun: Horizontal and Vertical Shape of a Region-Based Graph Compression , 2022, Sensors.

[23]  Junfei Fang,et al.  Wavelet analysis of plasma optical signals at pool penetration in laser welding , 2004, SPIE/COS Photonics Asia.