Characteristics of Plasma Emission Signals in Fiber Laser Welding for API Steel (Ⅰ) - Variation of Signals by Measuring Conditions

KIM, Jong-Do; LEE, Chang-Je; LEE, Mok-Young

Journal of KWJS 2010;28(6):51-57.
Published online January 10, 2011.

API강재의 화이버레이저 용접시 유기하는 플라즈마의 방사특성 (Ⅰ) - 측정조건에 따른 광신호의 변화

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Characteristics of Plasma Emission Signals in Fiber Laser Welding for API Steel (Ⅰ) - Variation of Signals by Measuring Conditions

Jong-Do KIM, Chang-Je LEE, Mok-Young LEE

Abstract

Fiber laser is a heat source which is introduced recently, and so has a little researched data compare with conventional laser processing. Moreover basic data for welding monitoring are also insufficient. Therefore, in this study, the change of signal with measuring position and angle of plasma emission signals were analysed as a basic experiment for real time monitoring in fiber laser welding. As a result, the signals measured from the side, front and rear had the biggest intensity at 60°, and frequency peak to reflect the behavior of keyhole and swing of plasma by shield gas was detected at 45 ~ 60°. However, both intensity of signal and the result of FFT for monitoring were satisfied at the angle of 45° from the side.

Key Words: Fiber laser, Laser welding, Plasma, Emission signal, Photodiode, RMS, FFT