Compressible friction stir welding tool for conventional machining equipment

1. A tool having a longitudinal axis, the tool comprising:

a friction stir welding (FSW) tool;

a first body configured to be connected to a tool holder and rotated about the longitudinal axis;

a second body mounted to the first body and rotatable therewith about the longitudinal axis;

a plurality of projections of one of the first and second bodies slidably received in axially elongated recesses of the other of the first and second bodies, the projections and recesses configured to permit relative axial movement of the first and second bodies and fix the first and second bodies against relative rotational movement; and

stop surfaces of the projections and the recesses extending transverse to the longitudinal axis and limiting axial movement of the first and second bodies relative to one another;

a releasable connection between the second body and the FSW tool;

the second body axially and rotationally fixed relative to the FSW tool with the second body connected to the FSW tool so that the second body moves axially and rotationally together with the FSW tool; and

a plurality of biasing elements positioned longitudinally between at least a portion of the first body and at least a portion of the second body, the biasing elements applying a restorative force upon relative axial movement of the first and second bodies toward one another.

2. The tool of claim 1 , wherein the first body is an arbor.

3. The tool of claim 1 , wherein at least one of the biasing elements of the plurality of biasing elements comprises a spring.

4. The tool of claim 1 , wherein at least one of the biasing elements of the plurality of biasing elements comprises a compressible fluid.

5. The tool of claim 1 , wherein the projections include mechanical fasteners.

6. The tool of claim 1 , wherein the first body and second body are rotationally fixed to the plurality of biasing elements.

7. The tool of claim 1 , wherein at least two of the biasing elements of the plurality of biasing elements are rotationally fixed relative to one another.

8. The tool of claim 7 , wherein the biasing elements of the plurality of biasing elements are at equal angular intervals around the longitudinal axis.

9. The tool of claim 1 , at least one of the biasing elements of the plurality of biasing elements being displaced in a perpendicular direction relative to the longitudinal axis.

10. The tool of claim 1 , at least one of the biasing elements of the plurality of biasing elements being selectively replaceable to adjust a restorative force of the tool.

11. The tool of claim 1 wherein the plurality of biasing elements include Belleville springs.

12. The tool of claim 1 wherein one of the first body and the second body includes an outer, tubular wall defining at least a portion of an interior cavity of the one of the first body and the second body; and

wherein the biasing elements are received at least partially in the cavity.

13. A friction stir welding (FSW) system, the system comprising:

a tool holder moveable at least in a longitudinal direction and rotatable about a rotational axis;

a FSW tool configured to rotate about the rotational axis; and

a load head configured to connect the FSW tool to the tool holder and rotate with the tool holder, the load head having a longitudinal axis and including:

a first body configured to be connected to the tool holder;

a second body mounted to the first body;

a plurality of projections of one of the first and second bodies slidably received in axially elongated recesses of the other of the first and second bodies, the projections and recesses configured to permit relative axial movement of the first and second bodies and fix the first and second bodies against relative rotational movement;

stop surfaces of the projections and the recesses extending transverse to the longitudinal axis and limiting axial movement of the first and second bodies relative to one another;

a releasable connection between the second body and the FSW tool;

the second body rotationally and axially fixed relative to the FSW tool with the second body connected to the FSW tool; and

a plurality of biasing elements positioned longitudinally between at least a portion of the first body and at least a portion of the second body.

14. The system of claim 13 , wherein the first body is an arbor.

15. The system of claim 13 , wherein the plurality of biasing elements responds to displacement of the first body and second body relative to one another according to Hooke's Law.

16. The tool of claim 13 , wherein the stop surfaces are configured to abut and limit axial movement of the first and second bodies away from one another.

17. The tool of claim 13 wherein one of the first and second bodies includes an outer, tubular wall defining at least a portion of an interior cavity of the one of the first and second bodies; and

wherein the biasing elements and a portion of the other of the first and second bodies are in the interior cavity.