Spiral spring for a horological movement

Patent metadata

Field	Value
Publication number	US-11913094-B2
Application number	US-202217654875-A
Country	US
Kind code	B2
Filing date	Mar 15, 2022
Priority date	Mar 16, 2021
Publication date	Feb 27, 2024
Grant date	Feb 27, 2024

Abstract

A spiral spring is configured to equip a balance of a horological movement. The spiral spring is made of an alloy consisting of: Nb, Ti and at least one element selected from V and Ta, optionally at least one element selected from Zr and Hf, optionally at least one element selected from W and Mo, possible traces of other elements selected from O, H, C, Fe, N, Ni, Si, Cu, Al, with the following weight percentages: a total content of Nb, V and Ta comprised between 40 and 85%, a total content of Ti, Zr and Hf comprised between 15 and 55%, a content for W and Mo respectively comprised between 0 and 2.5%, a content for each of the elements selected from O, H, C, Fe, N, Ni, Si, Cu, Al between 0 and 1600 ppm with the sum of the traces less than or equal to 0.3% by weight.

First claim

The invention claimed is:

1. A spiral spring configured to equip a balance of a horological movement, wherein the spiral spring is made of an alloy consisting of:
Nb;
Ti; and
V and/or Ta;
optionally, Zr;
optionally, Hf;
optionally, W;
optionally, Mo; and
optionally O, H, C, Fe, N, Ni, Si, Cu, and/or Al,
wherein a Ti content is at least 15 wt. %,
wherein a total content of the Nb, V, and Ta is in a range of from 40 to 85 wt. %,
wherein a total content of the Ti, Zr, and Hf is in a range of from 15 to 55 wt. %,
wherein a W content is in a range of from 0 to 2.5 wt. %,
wherein a Mo content is in a range of from 0 to 2.5 wt. %,
wherein a content for each of O, H, C, Fe, N, Ni, Si, Cu, and Al in a range of from 0 to 1600 ppm,
wherein a sum of the O, H, C, Fe, N, Ni, Si, Cu, and Al, is less than or equal to 0.3 wt. %, and
wherein the spiral spring has a modulus of elasticity of at least 110 GPa.

2. The spiral spring of claim 1 , wherein the Nb content is greater than 45 wt. %.

3. The spiral spring of claim 1 , wherein the Ti content is greater than or equal to 30 wt. %.

4. The spiral spring of claim 1 , wherein a sum of the V and Ta is in a range of from 5 to 25 wt. %.

5. The spiral spring of claim 1 , wherein a sum of V and Ta is in a range of from 10 to 25 wt. %.

6. The spiral spring of claim 1 , wherein a sum of the V and Ta is in a range of from 15 to 25 wt. %.

7. The spiral spring of claim 1 , wherein the Zr and/or Hf are present, and
wherein a sum of the Zr and Hf is in a range of from 1 to 40 wt. %.

8. The spiral spring of claim 1 , wherein the Zr and/or Hf are present, and
wherein a sum of the Zr and Hf is in a range of from 5 to 25 wt. %.

9. The spiral spring of claim 1 , wherein the Zr and/or Hf are present, and
wherein a sum of the Zr and Hf is in a range of from 10 to 25 wt %.

10. The spiral spring of claim 1 , wherein the Zr and/or Hf are present, and
wherein sum of the content of Zr and Hf is in a range of from 15 to 25 wt. %.

11. The spiral spring of claim 1 , having a microstructure comprising
a beta phase of (i) Nb, and of (ii-a) V and/or (ii-b) Ta, and
an alpha phase of (iii) Ti, and of (iii-a) Zr and/or of (iii-b) Hf when the alloy comprises Zr and/or Hf.

12. The spiral spring of claim 1 , having an elastic limit greater than or equal to 500 MPa.

13. A method for manufacturing the spiral spring of claim 1 , the method successively comprising:
beta type quenching a blank of the alloy, which is at least ternary, so that titanium of the alloy is essentially a solid solution with niobium, and vanadium and/or tantalum in beta phase, zirconium and/or hafnium of the alloy also being essentially a solid solution when the alloy comprises the zirconium and/or hafnium;
applying to the alloy a succession of sequences of deformation followed by an intermediate heat treatment;
winding to form the spiral spring;
applying a final heat treatment.

14. The method of claim 13 , wherein the beta type quenching is a dissolution treatment, with a duration in a range of from 5 minutes to 2 hours at a temperature in a range of from 700 to 1000° C. under vacuum, followed by cooling under gas.

15. The method of claim 13 , wherein the final heat treatment as well as the intermediate heat treatment of each sequence is a precipitation treatment of Ti, and optionally of Zr and/or Hf when the alloy comprises the Zr and/or Hf, in the alpha phase, with a duration in a range of from 1 to 200 hours at a holding temperature in a range of from 300 to 700° C.

16. The method of claim 13 , wherein, when the alloy comprises the Zr and/or Hf, the final heat treatment is carried out at a holding temperature in a range of from 400 to 600° C. for a duration in a range of from 4 to 8 hours.

17. The method of claim 13 , wherein, before the applying of the succession of sequences, a surface layer of ductile material comprising copper, nickel, cupro-nickel, cupro-manganese, gold, silver, nickel-phosphorus Ni—P, and/or nickel-boron Ni—B, is added to the blank to facilitate shaping into a wire, and
wherein, before or after the winding, the wire is chemically stripped of the surface layer of the ductile material.

Assignees

• Nivarox Far Sa

Inventors

• Charbon Christian
• Michelet Lionel
• Verardo Marco

Classifications

• C22C27/025 Primary

  alloys based on vanadium · CPC title

• G04B17/066 Primary

  Manufacture of the spiral spring (locking of the spiral spring by the regulating lever G04B18/026; spiral spring with temperature compensation G04B17/227; fixation of the spiral spring on the collet G04B17/32; mainspring G04B1/14) · CPC title

• C22C27/02 Primary

  Alloys based on vanadium, niobium, or tantalum · CPC title

• C22C30/00

  Alloys containing less than 50% by weight of each constituent · CPC title

• C22C14/00

  Alloys based on titanium · CPC title