Publication detail

Possibilities in optical monitoring of laser welding process

Horník Petr, Mrňa Libor

English title

Possibilities in optical monitoring of laser welding process

Type

conference paper

Language

en

Original abstract

Laser welding is a modern, widely used but still not really common method of welding. With increasing demands on the quality of the welds, it is usual to apply automated machine welding and with on-line monitoring of the welding process. The resulting quality of the weld is largely affected by the behavior of keyhole. However, its direct observation during the welding process is practically impossible and it is necessary to use indirect methods. At ISI we have developed optical methods of monitoring the process. Most advanced is an analysis of radiation of laser-induced plasma plume forming in the keyhole where changes in the frequency of the plasma bursts are monitored and evaluated using Fourier and autocorrelation analysis. Another solution, robust and suitable for industry, is based on the observation of the keyhole inlet opening through a coaxial camera mounted in the welding head and the subsequent image processing by computer vision methods. A high-speed camera is used to understand the dynamics of the plasma plume. Through optical spectroscopy of the plume, we can study the excitation of elements in a material. It is also beneficial to monitor the gas flow of shielding gas using schlieren method.

English abstract

Laser welding is a modern, widely used but still not really common method of welding. With increasing demands on the quality of the welds, it is usual to apply automated machine welding and with on-line monitoring of the welding process. The resulting quality of the weld is largely affected by the behavior of keyhole. However, its direct observation during the welding process is practically impossible and it is necessary to use indirect methods. At ISI we have developed optical methods of monitoring the process. Most advanced is an analysis of radiation of laser-induced plasma plume forming in the keyhole where changes in the frequency of the plasma bursts are monitored and evaluated using Fourier and autocorrelation analysis. Another solution, robust and suitable for industry, is based on the observation of the keyhole inlet opening through a coaxial camera mounted in the welding head and the subsequent image processing by computer vision methods. A high-speed camera is used to understand the dynamics of the plasma plume. Through optical spectroscopy of the plume, we can study the excitation of elements in a material. It is also beneficial to monitor the gas flow of shielding gas using schlieren method.

Keywords in English

laser welding; process monitoring; autocorrelation function

Released

01.01.2016

Publisher

SPIE-INT SOC OPTICAL ENGINEERING

Location

BELLINGHAM

ISSN

0277-786X

Book

OAM 2016-30

Volume

10151

Number

1

Edition number

1

Pages from–to

1–8

Pages count

6

BIBTEX


@inproceedings{BUT170091,
  author="Libor {Mrňa} and Petr {Horník},
  title="Possibilities in optical monitoring of laser welding process",
  booktitle="OAM 2016-30",
  year="2016",
  volume="10151",
  number="1",
  month="January",
  pages="1--8",
  publisher="SPIE-INT SOC OPTICAL ENGINEERING",
  address="BELLINGHAM",
  issn="0277-786X"
}