On-line quality monitoring in short - circuit gas metal arc welding

Document type: Journal Articles
Article type: Original article
Peer reviewed: Yes
Author(s): Stefan Adolfsson, Ali Bahrami, Ingvar Claesson, Gunnar Bolmsjö
Title: On-line quality monitoring in short - circuit gas metal arc welding
Journal: Welding Journal
Year: 1999
Volume: 78
Issue: 2
Pagination: 59S-73S
ISSN: 0043-2296
Publisher: American welding society
City: New York,N.Y.
ISI number: 000078532000021
Organization: Blekinge Institute of Technology
Department: Dept. of Signal Processing (Institutionen för signalbehandling)
Dept. of Signal Processing S-372 25 Ronneby
+46 455 780 00
Authors e-mail: Stefan.Adolfsson@isb.hk-r.se
Language: English
Abstract: This paper addresses the problems involved in the automatic monitoring of the weld quality produced by robotized short-arc welding. A simple statistical change detection algorithm for the weld quality, the repeated Sequential Probability Ratio Test (SPRT), was used. The algorithm may similarly be viewed as a cumulative sum (CUSUM) type test, and is well-suited to detecting sudden minor changes in the monitored test statistic. The test statistic is based on the variance of the weld voltage, wherein it will be shown that the variance decreases when the welding process is not operating under optimal conditions. The performance of the algorithm is assessed through the use of experimental data. The results obtained from the algorithm show that it is possible to detect changes in weld quality automatically and on-line.
Subject: Signal Processing\Detection and Classification
Note: Submitted for publication 1997