Proceedings of the KWS Conference (대한용접접합학회:학술대회논문집)
- 2002.10a
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- Pages.600-605
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- 2002
CONTROL OF LASER WELD KEYHOLE DYNAMICS BY POWER MODULATION
- Cho, Min-Hyun (Department of Welding Engineering, The Ohio State University) ;
- Dave Farson (Department of Welding Engineering, The Ohio State University)
- Published : 2002.10.01
Abstract
The keyhole formed by high energy density laser-material interaction periodically collapses due to surface tension of the molten metal in partial penetration welds. The collapse sometimes traps a void at the bottom of the keyhole, and it remains as welding defects. This phenomenon is seen as one cause of the instability of the keyhole during laser beam welding. Thus, it seems likely that improving the stability of the keyhole can reduce voids and uniform the penetration depth. The goal of this work is to develop techniques for controlling laser weld keyhole dynamics to reduce weld defects such as voids and inconsistent penetration. Statistical analysis of the penetration depth signals in glycerin determined that keyhole dynamics are chaotic. The chaotic nature of keyhole fluctuations and the ability of laser power modulation to control them have been demonstrated by high-speed video images of laser welds in glycerin. Additionally, an incident leading beam angle is applied to enhance the stability of the keyhole. The quasi-sinusoidal laser beam power of 400Hz frequency and 15