Welding head for friction stir welding

A friction stir welding head, comprising:

• a head housing that extends from a top end to an open bottom end and defines a bore extending between the top end and the open bottom end;
• one or more floating components configured to support a friction stir welding tool including a shoulder and a pin that is fixed with respect to the shoulder, the one or more floating components, the shoulder, and the pin being axially movable only as a single unit with respect to the head housing;
• and
• a load cell disposed beneath the open bottom end of the head housing, the load cell being configured to generate load signals in response to axial movement of the one or more floating components, the shoulder, and the pin,
• wherein the friction stir welding head is reconfigurable between a rotating shoulder configuration and a stationary shoulder configuration with a single installation operation.

A method of friction stir welding, comprising:

• providing a head housing that extends from a top end to an open bottom end and defines a bore extending between the top end and the open bottom end;
• installing a floating axle in the head housing, the floating axle including an engagement end that extends beyond the open bottom end, the engagement end supporting a friction stir welding tool that includes a shoulder and a pin that is fixed with respect to the shoulder, wherein the installing secures the floating axle within the head housing so that the floating axle, the pin, and the shoulder are laterally fixed with respect to the head housing and axially movable only as a single unit with respect to the head housing;
• installing a load cell on the open bottom end of the head housing;
• controlling rotating shoulder friction stir welding with the friction stir welding tool based on load signals generated by the load cell;
• and
• transitioning to stationary shoulder friction stir welding by installing a stationary shoulder housing onto the load cell.