Advanced multi-shouldered fixed bobbin tools for simultaneous friction stir welding of multiple parallel walls between parts

A multi-shouldered friction stir welding tool comprising:

• an exterior threaded solid pin having a diameter and a length;
• a shoulder having a threadless inner diameter slightly larger than the diameter of the exterior threaded solid pin and at least one substantially radial threaded set screw hole;
• an monolithic shoulder-shank having a threadless inner diameter slightly larger than the diameter of the exterior threaded solid pin and at least one substantially radial threaded set screw hole;
• a pair of locking nuts having a threadless outer diameter and a threaded inner diameter operably compatible with the exterior threaded solid pin,
• wherein the shoulder and the monolithic shoulder-shank are capable of slidable engagement with the exterior threaded solid pin along the length of the exterior threaded solid pin to set a space slightly larger than a thickness of a work piece to be welded.

A multi-shouldered friction stir welding tool comprising:

• an integral shank-pin unit having a plurality of pin portions on the shank-pin unit,
• wherein the plurality of pin portions for driving into a plurality of joints to perform a friction stir welding operation on the corresponding plurality of joints and,
• wherein a shank portion of the shank-pin unit is for attachment of an optional axial tension rod,
• a plurality of friction stir welding modules, each of the friction stir welding modules comprising:
• a pair of shoulders that is connected to the shank-pin unit where each shoulder has a distal end and a proximal end, where the proximal end of each shoulder faces the pin portion of the shank-pin unit, whereby the shoulder and pin(s) rotate in unison;
• and
• a pair of split collars or a pair of nuts that is connected to the shank-pin unit and faces the distal end of each shoulder;
• wherein the plurality of friction stir welding modules are connected to each other whereby the modules rotate in unison to simultaneously make a plurality of parallel welds.