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TWT method for temperature measurement during FSW process
University West, Department of Engineering Science, Division of Automation Systems. (PTW)ORCID iD: 0000-0003-3261-9097
University West, Department of Engineering Science, Division of Automation Systems. (PTW)ORCID iD: 0000-0001-9553-7131
University West, Department of Engineering Science, Division of Automation Systems. (PTW)ORCID iD: 0000-0002-1869-232X
2015 (English)In: The 4th international Conference on scientific and technical advances on friction stir welding & processing, San Sebastian, Spain, 2015, 95-98 p.Conference paper (Refereed)
Abstract [en]

Friction stir weld (FSW) has generated a high interest in many industry segments in the past 20 years. Along with new industrial challenges, more complex geometries and high quality demands, a better control of the welding process is required. New approaches using temperature controlled welding have been proposed and revealed good results. However, few temperature measurement methods exist which are accurate, fast and industrially suitable. A new and simple sensor solution, the Tool-Workpiece Thermocouple (TWT) method, based on the thermoelectric effect was recently developed.This paper presents a calibration solution for the TWT method where the TWT temperature is compared to calibrated thermocouples inside the tool. The correspondence between both methods is shown. Furthermore, a calibration strategy in different aluminium alloys is proposed, which is based on plunge iterations. This allows accurate temperature monitoring during welding, without the need for thermocouples inside the tool.

Place, publisher, year, edition, pages
San Sebastian, Spain, 2015. 95-98 p.
Keyword [en]
Friction stir welding, TWT method, Temperature measurements, Aluminium alloys
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
URN: urn:nbn:se:hv:diva-9122OAI: oai:DiVA.org:hv-9122DiVA: diva2:906841
Conference
The 4th international Conference on scientific and technical advances on friction stir welding & processing October 1-2, 2015
Available from: 2016-02-25 Created: 2016-02-25 Last updated: 2016-10-14Bibliographically approved
In thesis
1. Thermo-electric temperature measurements in friction stir welding: Towards feedback control of temperature
Open this publication in new window or tab >>Thermo-electric temperature measurements in friction stir welding: Towards feedback control of temperature
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Friction Stir Welding has seen a fast uptake in many industry segments. Mechanical properties superior to fusion welding, the ability to weld "unweldable" aluminium alloys and low distortion are often described as the main reasons for the fast industrial implementation of FSW. Most existing applications consist of long straight welding joints. Applications with complex weld geometries, however, are rarely produced by FSW. These geometries can induce thermal variations during the welding process, thus making it challenging to maintain a consistent weld quality. In-process adaptation of weld parameters to respond to geometrical variations and other environmental variants allow new design opportunities for FSW. Weld quality has been shown to be reliant on the welding temperature. However, the optimal methodology to control the temperature is still under development.The research work presented in this thesis focuses on some steps to take in order to reach the improvement of the FSW temperature controller, thus reach a better and consistent weld quality. In the present work different temperature methods were evaluated. Temperature measurements acquired by the tool-workpiece thermocouple (TWT) method were accurate and fast, and thereby enhanced suitable for the controller. Different environmental conditions influencing the material heat dissipation were imposed in order to verify the controller effect on the joint quality. In comparison with no controlled weld, the use of the controller enabled a fast optimization of welding parameters for the different conditions, leading to an improvement of the mechanical properties of the joint.For short weld lengths, such as stitch welds, the initial plunge and dwell stages occupy a large part of the total process time. In this work temperature control was applied during these stages. This approach makes the plunge and dwell stages more robust by preventing local material overheating, which could lead to a tool meltdown. The TWT method was demonstrated to allow a good process control during plunging and continuous welding. The approach proposed for control offers weld quality consistency and improvement. Also, it allows a reduction of the time required for the development of optimal parameters, providing a fast adaptation to disturbances during welding and, by decreasing the plunge time, provides a significant decrease on the process time for short welds.

Place, publisher, year, edition, pages
Trollhättan: University West, 2016. 62 p.
Keyword
FSW, Robotic, Temperature, TWT, Plunge, Control
National Category
Robotics
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-9982 (URN)978-91-87531-43-9 (ISBN)978-91-87531-42-2 (ISBN)
Supervisors
Available from: 2016-11-09 Created: 2016-10-12 Last updated: 2016-11-10Bibliographically approved

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Silva, AnaDe Backer, JeroenBolmsjö, Gunnar
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