A friction stir weld (FSW) system for welding and weld repair can be used on the manufacturing floor, as well as in the laboratory environment. This FSW system can be used in a wide variety of welding and weld repair applications. It is capable of handling up to 6,000 pounds (26.7 kN) of axial load while operating within close tolerances.

This FSW system includes seven subcomponents: a base foundation unit (BFU), a hydraulically controlled elevation platform (EP), the hydraulically adjustable pin tool (HAPT), backplate tooling, fixturing, a roller mechanism, and the real-time adaptive computer numerical control (CNC) and process control system (APCS). Together, these subcomponents allow the FSW to be used on the manufacturing floor as a complete welding system.

The Subcomponents of the Friction Stir Weld System for welding and weld repair function as one integrated welding system.

The BFU is unique to accommodate the internal mechanical entities of the system. It is designed to operate under the radial and axial loads associated with the FSW process. The hydraulically controlled EP is the result of novel applications of existing technologies to create an elevation feature with three axes of movement, specially designed to function under operating pressures. This movement is necessary to attain the proper pin tool location with respect to the center of the weld joint. The HAPT is a standalone piece of hardware, which was integrated into the FSW system. (However, the positioning of the a & b axis around the N axis is unique.) The APCS component was specially designed to function as an integrated controller for a variety of functions and data gathering operations.

The novelty of the FSW System for welding and weld repair is the fact that the seven subcomponents act as one integrated welding system. This system has unlimited applications in manufacturing where welded structures are vital to the fabrication cycle. This apparatus provides the capability for initial welding and weld repairs of friction stir welds and fusion welds.

This equipment is extremely energy efficient. A single-pass, 12.5-mm deep weld can be made in 6xxx series alloy using a gross power of no more than 3 kW. Also, the maintenance of this equipment is minimal, requiring no special operation or operator maintenance training. In addition, this machine tool is ideally suited to automation and integration with other machine-tool operations.

Another advantage of this system and its mode of operation is that there is no need for such consumables as filler wire or the shielding gas that is needed for welding aluminum alloys.

With this system, it is possible to make butt- and lap-seam welds between wrought, cast, and extruded materials, leading to simplification of manufacture.

Finally, the FSW process is a clean process, producing none of the health hazards such as welding fumes or radiation.

This work was done by Jeff Ding of Marshall Space Flight Center, Peter L. Romine of Florida International University, and Peter A. Oelgoetz of Boeing North American, Inc. MFS-30125


NASA Tech Briefs Magazine

This article first appeared in the January, 1998 issue of NASA Tech Briefs Magazine.

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