US Patent 7641096 Friction stir welding apparatus

A friction stir welding apparatus has a novel tool-in-tool construction where a friction stir welding pin tool extends through a center bore of a friction stir welding shoulder tool and is moveable axially and rotationally relative to the shoulder tool. The pin tool and shoulder tool both have their own dedicated tool holders and spindles that enable the tools to rotate and move axially relative to each other and enable easy replacement of each of the tools.