Research and Experimentation on Acoustic Monitoring Technology for Laser Drilling Penetration

To prevent back wall damage in cavity workpieces during laser drilling, it is crucial to monitor hole penetration status in real time. This study proposes a laser drilling penetration monitoring method based on acoustic principles. First, the acoustic module parameters of the system were simulated and calibrated using COMSOL Multiphysics (version 6.1) software, resulting in an optimal sound source frequency of 35 kHz and an incident angle of 30° for the acoustic waves. Next, a nickel-based alloy laser drilling acoustic monitoring platform was designed and constructed, and the system's upper computer control software was developed. Subsequent drilling trials were performed on the validated platform. During the experiments, the threshold for hole penetration signals under the specified experimental parameters was determined, enabling the acquisition of acoustic signals and the identification of hole penetration status. Furthermore, a correlation between the intensity of the acoustic signals and the exit aperture of the drilled holes was established. The results demonstrate the feasibility of using acoustic principles to monitor hole penetration status and measure machining aperture, providing both theoretical and experimental foundations for active laser drilling to prevent back wall damage.