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Friction Stir Welding of Tapered Thickness Welds Using an Adjustable Pin ToolFriction stir welding (FSW) can be used for joining weld lands that vary in thickness along the length of the weld. An adjustable pin tool mechanism can be used to accomplish this in a single-pass, full-penetration weld by providing for precise changes in the pin length relative to the shoulder face during the weld process. The difficulty with this approach is in accurately adjusting the pin length to provide a consistent penetration ligament throughout the weld. The weld technique, control system, and instrumentation must account for mechanical and thermal compliances of the tooling system to conduct tapered welds successfully. In this study, a combination of static and in-situ measurements, as well as active control, is used to locate the pin accurately and maintain the desired penetration ligament. Frictional forces at the pin/shoulder interface were a source of error that affected accurate pin position. A traditional FSW pin tool design that requires a lead angle was used to join butt weld configurations that included both constant thickness and tapered sections. The pitch axis of the tooling was fixed throughout the weld; therefore, the effective lead angle in the tapered sections was restricted to within the tolerances allowed by the pin tool design. The sensitivity of the FSW process to factors such as thickness offset, joint gap, centerline offset, and taper transition offset were also studied. The joint gap and the thickness offset demonstrated the most adverse affects on the weld quality. Two separate tooling configurations were used to conduct tapered thickness welds successfully. The weld configurations included sections in which the thickness decreased along the weld, as well as sections in which the thickness increased along the weld. The data presented here include weld metallography, strength data, and process load data.
Document ID
20040084011
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Adams, Glynn
(Lockheed Martin Michoud Space Systems New Orleans, LA, United States)
Venable, Richard
(Lockheed Martin Space Systems Co. Huntsville, AL, United States)
Lawless, Kirby
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
August 21, 2013
Publication Date
November 1, 2003
Publication Information
Publication: 5th Conference on Aerospace Materials, Processes, and Environmental Technology
Subject Category
Mechanical Engineering
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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