Friction stir additive manufacturing systems

1. An additive manufacturing system for depositing an extrudate onto a substrate, the additive manufacturing system comprising a deposition head that comprises:

a stirring tool, rotatable about an axis of rotation A R and comprising a tool distal end and a tool proximal end, axially opposing the tool distal end along the axis of rotation A R , wherein the stirring tool defines a bore, extending from the tool proximal end to the tool distal end, and the bore is configured to receive feedstock, biased toward the tool distal end; and

a die, which is positioned adjacent to the stirring tool, defines a die axis A D1 , and comprises a die distal end and a die proximal end, axially opposing the die distal end along the die axis A D1 , wherein the die axis A D1 is parallel to the axis of rotation A R of the stirring tool, and the stirring tool is rotatable relative to the die about the axis of rotation A R .

2. The additive manufacturing system according to claim 1 , wherein the die distal end axially protrudes a distance D beyond the tool distal end.

3. The additive manufacturing system according to claim 1 , wherein:

the die is moveable relative to the stirring tool along the die axis A D1 between, inclusively, at least a retracted position and an engaged position, and

the die distal end protrudes axially outward a distance D beyond the tool distal end when the die is in the engaged position.

4. The additive manufacturing system according to claim 3 , further comprising a die force applicator, operatively connected to the die to selectively move the die along the die axis A D1 between at least the retracted position and the engaged position.

5. The additive manufacturing system according to claim 1 , further comprising a stirring-tool force applicator, configured to urge the deposition head against the substrate.

6. The additive manufacturing system according to claim 5 , further comprising a stirring-tool rotation device, configured to rotate the stirring tool about the axis of rotation A R while the stirring-tool force applicator urges the deposition head against the substrate.

7. The additive manufacturing system according to claim 1 , further comprising a feed-stock force applicator that biases the feedstock toward the tool distal end.

8. The additive manufacturing system according to claim 1 , further comprising a carriage, connected to the deposition head, and wherein the carriage moves the deposition head relative to the substrate.

9. The additive manufacturing system according to claim 1 , wherein the die comprises an engagement surface that defines at least one shaping feature.

10. The additive manufacturing system according to claim 1 , wherein the die is rotatable about the die axis A D1 .

11. The additive manufacturing system according to claim 10 , further comprising a die-rotation device, operatively connected to the die to rotate the die about the die axis A D1 .

12. The additive manufacturing system according to claim 10 , further comprising a second die, which is positioned adjacent to the stirring tool, defines a second-die axis A D2 , and comprises a second-die distal end and a second-die proximal end, axially opposing the second-die distal end along the second-die axis A D2 , and wherein the second-die axis A D2 is parallel with the axis of rotation A R of the stirring tool.

13. The additive manufacturing system according to claim 12 , wherein the second die is rotatable about the second-die axis A D2 .

14. The additive manufacturing system according to claim 13 , wherein:

the die is rotatable in a first direction R 1 about the die axis A D1 and the second die is rotatable in a second direction R 2 about the second-die axis A D2 ; and

the first direction R 1 and the second direction R 2 are opposite to each other.

15. The additive manufacturing system according to claim 1 , wherein:

the stirring tool comprises an outer surface, and

a shortest distance between the die and the outer surface is at most 3 millimeters.

16. The additive manufacturing system according to claim 1 , wherein:

the stirring tool comprises an outer surface, and

a shortest distance between the die and the outer surface is at most 1 millimeter.

17. The additive manufacturing system according to claim 1 , wherein the feedstock is received in the bore such that rotation of the stirring tool causes corresponding rotation of the feedstock.

18. The additive manufacturing system according to claim 1 , wherein the feedstock comprises a metal or a metal alloy.

19. The additive manufacturing system according to claim 1 , wherein:

the die is formed of a first metallic material, having a first composition;

the stirring tool is formed of a second metallic material, having a second composition; and

the first composition and the second composition are equivalent to each other.

20. An additive manufacturing system for depositing an extrudate onto a substrate, the additive manufacturing system comprising a deposition head that comprises:

a stirring tool, rotatable about an axis of rotation A R and comprising a tool distal end and a tool proximal end, axially opposing the tool distal end along the axis of rotation A R , wherein the stirring tool comprises a bore, extending from the tool proximal end to the tool distal end, and the bore is configured to receive feedstock, biased toward the tool distal end; and

a die, which is positioned adjacent to the stirring tool, defines a die axis A D1 , and comprises a die distal end and a die proximal end, axially opposing the die distal end along the die axis A D1 , wherein the die axis A D1 is parallel to the axis of rotation A R of the stirring tool, and the die distal end axially protrudes a distance D beyond the tool distal end.