Patent ID: 7641096

Claim:
A friction stir welding apparatus comprising: a friction stir welding pin tool having a length with opposite proximal and distal ends and a center axis extending through the pin tool length; a friction stir welding shoulder tool having a length with opposite proximal and distal ends and a center bore extending through the shoulder tool; the pin tool being mounted in the shoulder tool bore for independent rotational and linear movement of the pin tool relative to the shoulder tool in the shoulder tool bore; a pin tool rotation source operatively connected to the pin tool for rotating the pin tool independently of the shoulder tool; a shoulder tool rotation source operatively connected to the shoulder tool independent of the pin tool rotation source, for rotating the shoulder tool independently of rotation of the pin tool, the shoulder tool rotation source being separate from the pin tool rotation source and the shoulder tool being movable linearly independently of said pin tool and in either a common rotational direction with said pin tool or an opposite rotational directional of a rotation of said pin tool; a shoulder tool holder for holding the shoulder tool stationary relative to the shoulder tool rotation source, the shoulder tool have an enlarged end portion forming a cavity; and a pin tool holder for holding the pin tool stationary relative to the pin tool rotation source, the pin tool holder being shaped and of dimensions such that a portion of the pin tool holder is housed within the cavity of the shoulder tool holder and concentrically with the shoulder tool holder, and such that the pin tool extends concentrically through the shoulder tool holder and the shoulder tool.