Coaxial monitoring of penetration in CO2 laser welding

Abstract

A system for coaxial monitoring the penetration status in CO2 laser beam welding has been established. Four kinds of penetration statuses, “partial penetration”, “weld pool penetration”, “moderate full penetration (keyhole penetration)” and “excessive penetration” are defined to describe the weld quality, and the status of “moderate full penetration” is as the benchmark of penetration monitoring and control. The experimental results show that a maximum increase slope in the signal intensity occurs at the status of “moderate full penetration” for flat-plate welding; for oblique-plate welding, the signal intensity is maximum at the “moderate full penetration”. In frequency field, FBC (barycenter of frequency spectrum) is presented to describe the characteristic of the frequency spectrum of the plasma optical signal. It is found that the FBC of 2-6 kHz range jumps up to higher frequency at the “moderate full penetration” for flat-plate welding; but for oblique-plate welding, the FBC of 2-6 kHz range is minimum at the “moderate full penetration”.A system for coaxial monitoring the penetration status in CO2 laser beam welding has been established. Four kinds of penetration statuses, “partial penetration”, “weld pool penetration”, “moderate full penetration (keyhole penetration)” and “excessive penetration” are defined to describe the weld quality, and the status of “moderate full penetration” is as the benchmark of penetration monitoring and control. The experimental results show that a maximum increase slope in the signal intensity occurs at the status of “moderate full penetration” for flat-plate welding; for oblique-plate welding, the signal intensity is maximum at the “moderate full penetration”. In frequency field, FBC (barycenter of frequency spectrum) is presented to describe the characteristic of the frequency spectrum of the plasma optical signal. It is found that the FBC of 2-6 kHz range jumps up to higher frequency at the “moderate full penetration” for flat-plate welding; but for oblique-plate welding, the FBC of 2-6 kHz range is minim...