레이저 강판 용접을 위한 실시간 모니터링 시스템에 관한 연구

Abstract

As non-stationary signal such as welding signal has a widespread observation band, digital low-pass filter (LPF) needs to be set at the frequency that is higher by 10 than the basic frequency of welding signal so as to receive the welding signal without attenuation. Since a momentary vibration signal has a wide frequency band, use of the BPF is not enough to remove only noise from external environment effectively. As a way to resolve such problem, de-noising method with use of fast wavelet transform (FWT) is more effective. In this study, when S45C steel plate was used for bead-on-plate (BOP) welding with change in power of laser beam, the welding signal emitted from key hole was applied to the LPF, and the FWT was performed for only frequency band of the welding signal. This method enables decomposition level to be reduced more significantly than the case where only the FWT is performed, which leads to convenience of realizing a real-time welding monitoring.