HYPERELASTIC SHAPE SETTING DEVICES AND FABRICATION METHODS

• US 20110226379A2
• Filed: 11/22/2010
• Published: 09/22/2011
• Est. Priority Date: 12/03/2007
• Status: Active Grant

• Current Assignee: Ormco Corporation (Envista Holdings Corporation)
• Original Assignee: Ormco Corporation (Envista Holdings Corporation)
• Inventors: Johnson, Alfred
• Granted Patent: US 8,382,917 B2
• Time in Patent Office: Days
• US Class Current: 140/071.00R
• CPC Class Codes: A61C 2201/007 using shape memory effect
• CPC Class Codes: A61C 7/20 Arch wires A61C7/28 takes precedence
• CPC Class Codes: C22C 9/01 with aluminium as the next major constituent
• CPC Class Codes: C22F 1/00 Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working apparatus for mechanical working of metal B21, B23, B24
• CPC Class Codes: C22F 1/006 Resulting in heat recoverable alloys with a memory effect
• CPC Class Codes: C30B 29/52 Alloys
• CPC Class Codes: C30B 33/02 Heat treatment C30B33/04, C30B33/06 take precedence

Abstract

Shape-setting methods for fabricating devices made of single crystal shape memory alloys. In particular the methods described may be used to fabricate dental arches of single-crystal shape memory alloys. The methods include drawing a single crystal of a shape memory alloy from a melt of the alloy. This is followed by heating, forming, and quenching the crystal sufficiently rapid to limit the formation of alloy precipitates to an amount which retains hyperelastic composition and properties of the crystal.

Claims

1. A method of shape-setting a wire of single-crystal shape memory alloy into an arched wire shape so that it is comprised of a single-crystal shape memory alloy, the method comprising the steps of:

heating the wire to a first temperature sufficient for annealing the alloy;

forcing the wire into an arched shape while the wire is held at the first temperature, wherein the heating and forcing steps are performed in less than 10 seconds; and

rapidly cooling the alloy to room temperature sufficiently quickly to cause the alloy to form a single-crystal.

2. The method of claim 1, wherein the steps of heating and forcing the wire are performed for less than 1 second before the cooling step.

3. The method of claim 1, wherein the step of rapidly cooling comprises cooling the wire to room temperature from the first temperature in less than about 0.5 second.

4. The method of claim 1, wherein the steps of heating, forcing and cooling are all performed in less than about 5 seconds.

5. The method of claim 1, wherein the step of forcing the wire into an arched shape comprises rapidly contacting the heated wire with a mandrel.

6. The method of claim 5, wherein the step of forcing the wire into an arched shape comprises dropping the mandrel against the heated wire.

7. The method of claim 6, wherein the step of rapidly cooling the wire comprises dropping the heated wire and mandrel into a cooling bath.

8. The method of claim 1, wherein the step of forcing the wire into an arched shape comprises forcing the wire into a dental arch shape having a round diameter of between about 0.013 to about 0.026 inches.

9. The method of claim 1, wherein the step of forcing the wire into an arched shape comprises forcing the wire into a dental arch shape having rectangular dimensions of between about 0.016 by 0.016 inches and about 0.020 by 0.030 inches.

12. A dental arch formed by the method of claim 1.

10. A method of shape-setting a wire of single-crystal alloy into a dental arch so that it is comprised of a single-crystal shape memory alloy, the method comprising the steps of:

heating the wire to an annealing temperature sufficient for annealing the alloy;

forcing the heated wire into a dental arch shape by forcing the wire against a mandrel, wherein the steps of heating and forcing the wire against the mandrel are performed in less than 10 seconds; and

rapidly cooling the wire by quenching to a cooling temperature sufficiently quickly to cause the alloy to remain a single-crystal in the dental arch shape.

13. A dental arch formed by the method of claim 10.

11. A method of shape-setting an alloy into a dental arch so that it is comprised of a single-crystal CuAlNi shape memory alloy, the method comprising the steps of:

heating a wire of CuAlNi alloy to a first temperature sufficient to place the Cu, Al and Ni in solution;

rapidly quenching the alloy to a second temperature to prevent precipitation of the Cu, Al and Ni so that the alloy remains as a single-crystal of CuAlNi;

constraining the alloy into a dental arch shape;

heating the alloy to a third temperature for a first time period, wherein the third temperature and first time period are sufficient to cause the alloy to lose its strength; and

cooling the alloy to a fourth temperature for a second time period, wherein the fourth temperature and second time period are sufficient to cause the alloy to remain a single-crystal in the shape.

14. A dental arch formed by the method of claim 11.

15. A dental arch comprising a hyperelastic, single-crystal shape memory material, the dental arch having an elongate, curved length that is configured to fit within a human mouth.

16. The dental arch of claim 15, wherein the curved elongate length has a round diameter of between about 0.013 to about 0.026 inches.

17. The dental arch of claim 15, wherein the curved elongate length has a rectangular cross-section with dimensions of between about 0.016 by 0.016 inches and about 0.020 by 0.030 inches.

18. The dental arch of claim 15, wherein the single-crystal shape memory alloy comprises a CuAlNi single crystal material.

19. The dental arch of claim 15, wherein the single-crystal shape memory alloy is selected from the group consisting of:

CuAlMb single crystal material;

CuAlMn single crystal material, CuAlBe single crystal material, and CuAlNb single crystal material.

20. The dental arch of claim 15, wherein different regions along the length of the dental arch have different material properties.

21. The dental arch of claim 15, wherein the ends of the dental arch wire are in the martensitic phase at body temperature.

22. An apparatus for forming a wire of shape memory alloy into a dental arch while preserving the single-crystal nature of the wire, the apparatus comprising:

a power source for heating the wire to above an annealing temperature of the shape memory alloy;

a holder for holding the ends of the wire so that the wire may be heated by the power source;

a mandrel for shaping the wire;

a driver for driving the mandrel against the heated wire held by the holder; and

a quenching sub-assembly for rapidly quenching the wire connected to the mandrel to room temperature within less than about 1 second.

23. The apparatus of claim 22, wherein the power source is an electrical power supply configured to apply power to the wire to heat the wire to a temperature above the annealing temperature of the shape memory alloy forming the wire.

24. The apparatus of claim 22, wherein the power source is a variable voltage source.

25. The apparatus of claim 22, wherein the power source is configured to heat the wire to a temperature of greater than 600 degrees.

26. The apparatus of claim 22, wherein the holder comprises a pair of clamps configured to electrically connect the wire to the power source.

27. The apparatus of claim 22, wherein the mandrel comprises an arced shape configured to form a dental arch.

28. The apparatus of claim 22, wherein the mandrel is connected to the driver and configured to drop against the wire secured by the holder, dropping the wire into the quenching sub-assembly.

29. The apparatus of claim 22, wherein the driver comprises a plunger.

30. The apparatus of claim 22, wherein the quenching sub-assembly comprises a bath configured to hold salt water.

31. An apparatus for forming a wire of shape memory alloy into a dental arch while preserving the single-crystal nature of the wire, the apparatus comprising:

a voltage source for heating the wire to above an annealing temperature of the shape memory alloy;

a pair of conductive holders for holding the ends of the wire in electrical communication with the voltage source so that the wire can be heated by the power source;

a curved mandrel for shaping the wire;

a plunger above the mandrel for driving the mandrel against the heated wire held by the holder; and

a quenching sub-assembly comprising a bath positioned below the mandrel and plunger and configured to receive the mandrel and wire to rapidly quench the wire to room temperature within less than about 1 second.