US 12,248,277 B2
Spiral spring for a horological movement and manufacturing method thereof
Lionel Michelet, Fleurier (CH); Christian Charbon, Chezard-St-Martin (CH); and Marco Verardo, Les Bois (CH)
Assigned to Nivarox-FAR S.A., Le Locle (CH)
Appl. No. 17/779,659
Filed by Nivarox-FAR S.A., Le Locle (CH)
PCT Filed Nov. 27, 2020, PCT No. PCT/EP2020/083622
§ 371(c)(1), (2) Date May 25, 2022,
PCT Pub. No. WO2021/105352, PCT Pub. Date Jun. 3, 2021.
Claims priority of application No. 19212457 (EP), filed on Nov. 29, 2019.
Prior Publication US 2022/0413438 A1, Dec. 29, 2022
Int. Cl. G04B 17/06 (2006.01)
CPC G04B 17/066 (2013.01) 24 Claims
OG exemplary drawing
 
1. A method for manufacturing a spiral spring suitable to equip a balance wheel of a horological movement, the method comprising:
(b) beta-quenching a blank comprising an Nb—Ti core consisting of titanium, one or more trace elements, and a remainder of niobium, so that the titanium of the Nb—Ti core is in the form of a solid solution with the niobium in beta-phase, the trace elements being O, H, C, Fe, Ta, N, Ni, Si, Cu, and/or Al, each of the trace elements being present in a range of from 0 to 1600 ppm by weight, a total amount of all of the elements being in a range of from 0 to 0.3 wt. %;
(c) deforming the blank in at least two sequences;
(d) winding in order to form the spiral spring; and
(e) final heat treatment on the spiral spring;
wherein either (i) the blank in the beta-quenching (b) comprises, around the Nb—Ti core, a layer of X with a material X comprising Cu, Sn, Fe, Pt, Pd, Rh, Al, Au, Ni, Ag, Co, and/or Cr, or (ii) the method comprises supplying the material X around the Nb—Ti core to form the layer of X anytime between before the beta-quenching and the deforming (c),
wherein the method further comprises a transformative heat treatment for a time period in a range of from 15 minutes to 100 hours, at a temperature in a range of from 200 to 900° C., to partially transform the layer of X into a layer of X,Ti intermetals around the Nb—Ti core, the blank thus successively comprising the Nb—Ti core, the layer of X, Ti intermetals, and part of the layer of X, the transformative heat treatment being carried out between the beta-quenching (b) and the deforming (c) or between two sequences of the deforming (c),
wherein the layer of X,Ti intermetals has a thickness in a range of from 20 nm to 10 μm, and
wherein the method further comprises removing the part of the layer of X, the removing being carried out between the beta-quenching (b) and the deforming (c), between two sequences of the deforming (c), or between the deforming (c) and the winding (d).