Noncontact acoustic analysis monitoring of plasma arc welding

This paper addresses the problems involved in the automatic monitoring of t he weld quality produced by plasma-are keyhole welding. The acoustic signal of plasma are welding was acquired by using a condenser microphone at high speed and analyzed with the aid of computers. It is shown that the overall AC power of the acoustic analysis, especially the low frequency part (0-10 0 Hz) of the acoustic signal power spectra, greatly varies with the variati on of the statuses of the weld pool. A method for detecting the behaviours of the keyhole effect of plasma-are welding was developed. The experimental results indicate that the method is a usable, practical one in the penetra tion quality monitoring of plasma-arc welding for on-line quality control. (C) 2001 Elsevier Science Ltd. All rights reserved.