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In‐process gap detection in friction stir welding

Paul Fleming (Welding Automation Laboratory, Vanderbilt University, Nashville, Tennessee, USA)
David Lammlein (Welding Automation Laboratory, Vanderbilt University, Nashville, Tennessee, USA)
D. Wilkes (Welding Automation Laboratory, Vanderbilt University, Nashville, Tennessee, USA)
Katherine Fleming (Center for Intelligent Systems, Vanderbilt University, Nashville, Tennessee, USA)
Thomas Bloodworth (Welding Automation Laboratory, Vanderbilt University, Nashville, Tennessee, USA)
George Cook (Welding Automation Laboratory, Vanderbilt University, Nashville, Tennessee, USA)
Al Strauss (Welding Automation Laboratory, Vanderbilt University, Nashville, Tennessee, USA)
David DeLapp (Welding Automation Laboratory, Vanderbilt University, Nashville, Tennessee, USA)
Thomas Lienert (Los Alamos National Laboratory, Los Alamos, California, USA)
Matthew Bement (Los Alamos National Laboratory, Los Alamos, California, USA)
Tracie Prater (Welding Automation Laboratory, Vanderbilt University, Nashville, Tennessee, USA)

Sensor Review

ISSN: 0260-2288

Article publication date: 25 January 2008

996

Abstract

Purpose

This paper aims to investigate methods of implementing in‐process fault avoidance in robotic friction stir welding (FSW).

Design/methodology/approach

Investigations into the possibilities for automatically detecting gap‐faults in a friction stir lap weld were conducted. Force signals were collected from a number of lap welds containing differing degrees of gap faults. Statistical analysis was carried out to determine whether these signals could be used to develop an automatic fault detector/classifier.

Findings

The results demonstrate that the frequency spectra of collected force signals can be mapped to a lower dimension through discovered discriminant functions where the faulty welds and control welds are linearly separable. This implies that a robust and precise classifier is very plausible, given force signals.

Research limitations/implications

Future research should focus on a complete controller using the information reported in this paper. This should allow for a robotic friction stir welder to detect and avoid faults in real time. This would improve manufacturing safety and yield.

Practical implications

This paper is applicable to the rapidly expanding robotic FSW industry. A great advantage of heavy machine tool versus robotic FSW is that the robot cannot supply the same amount of rigidity. Future work must strive to overcome this lack of mechanical rigidity with intelligent control, as has been examined in this paper.

Originality/value

This paper investigates fault detection in robotic FSW. Fault detection and avoidance are essential for the increased robustness of robotic FSW. The paper's results describe very promising directions for such implementation.

Keywords

Citation

Fleming, P., Lammlein, D., Wilkes, D., Fleming, K., Bloodworth, T., Cook, G., Strauss, A., DeLapp, D., Lienert, T., Bement, M. and Prater, T. (2008), "In‐process gap detection in friction stir welding", Sensor Review, Vol. 28 No. 1, pp. 62-67. https://doi.org/10.1108/02602280810850044

Publisher

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Emerald Group Publishing Limited

Copyright © 2008, Emerald Group Publishing Limited

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