Process for producing a balance wheel for a timepiece

Patent metadata

Field	Value
Publication number	US-11640140-B2
Application number	US-202217669476-A
Country	US
Kind code	B2
Filing date	Feb 11, 2022
Priority date	Dec 22, 2017
Publication date	May 2, 2023
Grant date	May 2, 2023

Abstract

A process for producing a metal alloy balance wheel by molding includes a) making a mold in the negative shape of the balance wheel; b) obtaining a metal alloy that has a thermal expansion coefficient of less than 25 ppm/° C. and is able to be in an at least partly amorphous state when it is heated to a temperature between its glass transition temperature and its crystallization temperature; c) putting the metal alloy into the mold, the metal alloy being heated to a temperature between its glass transition temperature and its crystallization temperature so as to be hot-molded and to form a balance wheel; d) cooling the metal alloy to obtain a balance wheel made of the metal alloy; and e) releasing the balance wheel obtained in step d) from its mold. The process also includes a step for over-molding flexible centering components in the hub.

First claim

What is claimed is:

1. A process for producing a balance wheel for a timepiece comprising a serge, a hub and at least one arm connecting the hub to said serge, the serge, the hub and the arm being made of a metal alloy, said process comprising the following steps:
a) making a mold in the negative shape of the balance wheel
b) obtaining a metal alloy that has a thermal expansion coefficient of less than 25 ppm/° C. and is able to be in an at least partly amorphous state when it is heated to a temperature between its glass transition temperature and its crystallization temperature
c) putting the metal alloy into the mold, said metal alloy being heated to a temperature between its glass transition temperature and its crystallization temperature so as to be hot molded and to form a balance wheel
d) cooling said metal alloy to obtain a balance wheel made of said metal alloy
e) releasing the balance wheel obtained in step d) from its mold,
wherein the process includes a step for over-molding flexible centering components in the hub.

2. The process according to claim 1 , wherein it includes a step of over-molding first inertia adjusting components in the serge, said first inertia adjusting components being made of a first material having a density that is greater than the density of said metal alloy.

3. The process according to claim 1 , wherein the serge includes recesses designed to receive second inertia adjusting and/or unbalance compensating components.

4. The process according to claim 1 , wherein the serge includes recesses designed to receive decorative and/or luminescent elements.

5. The process according to claim 1 , wherein said centering components are located on an inside circumference of the hub.

6. The process according to claim 1 , wherein it includes a step to over-mold third flexible inertia adjusting components in the arm.

7. The process according to claim 1 , wherein the mold has microstructures forming a decor or a photonic network.

8. The process according to claim 1 , wherein said metal alloy is based on an element selected from among the group consisting of platinum, zirconium, titanium, palladium, nickel, aluminum and iron.

9. The process according to claim 1 , wherein said metal alloy is based on platinum and has a thermal expansion coefficient of less than 12 ppm/° C.

10. The process according to claim 9 , wherein said metal alloy is based on platinum and has a thermal expansion coefficient between 8 ppm/° C. and 12 ppm/° C.

11. The process according to claim 9 , wherein the metal alloy based on platinum is made, in atomic % values, of
a base of platinum, whose concentration constitutes the balance,
13 to 17% copper,
3 to 7% nickel, and
20 to 25% phosphorus.

12. The process according to claim 1 , wherein said metal alloy is based on zirconium and has a thermal expansion coefficient that is smaller than 12 ppm/° C.

13. The process according to claim 12 , wherein said metal alloy is based on zirconium and has a thermal expansion coefficient between 8 ppm/° C. and 11 ppm/° C.

14. The process according to claim 12 , wherein the metal alloy based on zirconium is made, in atomic % values, of
a base of zirconium, whose concentration constitutes the balance,
14 to 20% copper,
12 to 13% nickel,
9 to 11% aluminium, and
2 to 4% niobium.

15. The process according to claim 1 , wherein said metal alloy is based on palladium and has a thermal expansion coefficient that is less than 20 ppm/° C.

16. The process according to claim 15 , wherein said metal alloy is based on palladium and has a thermal expansion coefficient that is between 13 ppm/° C. and 18 ppm/° C.

17. The process according to claim 15 , wherein the metal alloy based on palladium is made, in atomic % values, of
a base of palladium, whose concentration constitutes the balance,
25 to 30% copper,
8 to 12% nickel, and
18 to 22% phosphorus.

18. A process for producing a balance wheel of a timepiece comprising a serge, a hub and at least one arm connecting the hub to said serge, the hub and the arm being made of a metal alloy, and the serge being made of a second material having a density that is greater than the density of said metal alloy of which the hub and the arm are made, said process including the following steps:
a) making a mold in the negative shape of the balance wheel;
a′) inserting a serge or serge parts made of a material that has a density higher than the density of said metal alloy into the mold;
b) obtaining a metal alloy that has a thermal expansion coefficient of less than 25 ppm/° C. and is able to be in an at least partly amorphous state when it is heated to a temperature between its glass transition temperature and its crystallization temperature;
c) putting the metal alloy into the mold, said metal alloy being heated to a temperature between its glass transition temperature and its crystallization temperature so as to be hot-molded, and over-molding the serge or the parts of the serge so as to mold a balance wheel with inserts;
d) cooling said metal alloy so as to obtain a balance wheel with inserts; and
e) releasing the balance wheel obtained in step d) from its mold,
wherein the process includes a step for over-molding flexible centering components in the hub.

Assignees

• Swatch Group Res & Dev Ltd

Inventors

• Haemmerli Alexandre
• Gueissaz Francois
• Martin Jean-Claude
• Paratte Lionel
• Winkler Yves
• Di Domenico Gianni
• Winkler Pascal
• Helfer Jean-Luc
• Tombez Lionel
• Hinaux Baptiste
• Corson Donald William
• Willemin Michel

Classifications

• G04B18/006

  by adjusting the devices fixed on the balance (construction of the pendulum G04B17/063; balancing G04B17/28) · CPC title

• C22C16/00

  Alloys based on zirconium · CPC title

• B22D25/026

  Casting jewelry articles (B22D13/063 takes precedence) · CPC title

• C22C38/08

  containing nickel {(C22C38/105 takes precedence)} · CPC title

• C22C21/00

  Alloys based on aluminium · CPC title