# US 11,898,225 B2 · Spiral spring for a horological movement

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- Number: US 11,898,225 B2
- Document ID: US11898225B2
- Status: Granted
- Kind: B2
- Application number: 17/654,870
- Filed: 2022-03-15
- Published: 2022-09-22
- Granted: 2024-02-13
- Earliest claimed: 2021-03-16
- Assignees: Nivarox-FAR S.A.
- Applicants: Nivarox-FAR S.A.
- Inventors: Christian Charbon; Lionel Michelet; Marco Verardo
- Web page: https://patentgrep.com/patent/US11898225B2

## CPC

- C22C 27/02: Alloys based on vanadium, niobium, or tantalum
- C22C 14/00: Alloys based on titanium
- C22C 16/00: Alloys based on zirconium
- C22F 1/18: High-melting or refractory metals or alloys based thereon
- C22F 1/183: {of titanium or alloys based thereon}
- C22F 1/186: {of zirconium or alloys based thereon}
- G04B 17/066: {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)}
- G04B 17/227: {composition and manufacture of the material used (composition and manufacture of hairsprings G04B17/066; of springs G04B1/145; anti-magnetic alloys G04B43/007; ferrous alloys C22C; non-ferrous alloys C22C, B22F)}
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- C22F: CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass, C23F17/00)
- G04B: MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS (spring- or weight-driven mechanisms in general F03G; electromechanical clocks or watches G04C; electromechanical clocks with attached or built-in means operating any device at pre-selected times or after predetermined time intervals G04C23/00; clocks or watches with stop devices G04F7/08)

## Abstract

A spiral spring intended to equip a balance of a horological movement, wherein the spiral spring is made of an alloy consisting of Nb, Ti and 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, Ta, C, Fe, N, Ni, Si, Cu, Al, with the following weight percentages: a content of Nb comprised between 40 and 84%, a total content of Ti, Zr and Hf comprised between 16 and 55%, a content for W and Mo respectively comprised between 0 and 2.5%, a content for each of said elements selected from O, H, Ta, C, Fe, N, Ni, Si, Cu, Al comprised between 0 and 1600 ppm with the sum of said traces less than or equal to 0.3% by weight. The method for manufacturing the spiral spring is also disclosed.

## Claims

### Claim 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 in a range of from 40 to 84 wt. %;
Ti in at least 15 wt. %; and
Zr and/or Hf;
optionally, W;
optionally, Mo; and
optionally, O, H, Ta, C, Fe, N, Ni, Si, Cu, and/or Al,
wherein a total content of the Ti, Zr, and Hf is in a range of from 16 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 the O, H, Ta, C. Fe, N, Ni, Si, Cu, and Al is in a range of from 0 to 1600 ppm,
wherein sum of the O, H, Ta, 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.

### Claim 2 (depends on 1)

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

### Claim 3 (depends on 1)

The spiral spring according to claim 1, wherein the Ti content is greater than or equal to 15 wt. %.

### Claim 4 (depends on 1)

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

### Claim 5 (depends on 1)

The spiral spring of claim 1, wherein a sum of the Zr and the Hf is in a range of from 1 to 25 wt. %.

### Claim 6 (depends on 1)

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

### Claim 7 (depends on 1)

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

### Claim 8 (depends on 1)

The spiral spring of claim 1, wherein the Zr is present at least 5 wt. %.

### Claim 9 (depends on 1)

The spiral spring of claim 1, wherein the Zr and the Hf are present.

### Claim 10 (depends on 1)

The spiral spring of claim 1, having a microstructure comprising
Nb in the beta phase, and
Ti as well as Zr and/or Hf in the alpha phase.

### Claim 11 (depends on 1)

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

### Claim 12 (depends on 1)

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

### Claim 13 (depends on 12)

The method of claim 12, 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° C. to 1000° C., under vacuum, followed by cooling under gas.

### Claim 14 (depends on 12)

The method of claim 12, wherein the beta type quenching is a dissolution treatment lasting 1 hour at 800° C. under vacuum, followed by cooling under gas.

### Claim 15 (depends on 12)

The method of claim 12, wherein the final heat treatment and the intermediate heat treatment of each sequence is a precipitation treatment of (i) Ti and of (ii-a) Zr and/or (ii-b) Hf in the alpha phase with a duration in a range of from 1 hour and 200 hours at a holding temperature in a range of from 300° C. to 700° C.

### Claim 16 (depends on 12)

The method of claim 12, wherein the final heat treatment is carried out at a holding temperature in a range of from 400° C. to 600° C. for a duration in a range of from 4 and 8 hours.

### Claim 17 (depends on 12)

The method of claim 12, 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 step, the wire is chemically stripped of the surface layer of ductile material.