Method for fabrication of a timepiece balance spring

Abstract

Method for fabrication of an antiferromagnetic and temperature compensated timepiece balance spring, including the steps of: selecting an amagnetic iron-chromium-nickel-manganese-beryllium compensating alloy, comprising, by mass percent, between and including: from 21.0% to 25.0% of manganese, from 9.0% to 13.0% of nickel, from 6.0% to 15.0% of chromium, from 0.2% to 2.0% of beryllium, the remainder iron, the total of nickel and manganese being higher than or equal to 33.0%, working the alloy to obtain a blank, shaping the blank by casting and/or forging and/or wire drawing and/or rolling and/or drawing, to obtain a blank of spring wire; winding the wire on a winder to obtain a balance spring, subjecting the spiral spring to at least a heat setting treatment, by annealing at a temperature comprised between 540 C. and 650 C., for a duration of 30 to 200 minutes, to obtain a balance spring.

Claims

1. A method for fabricating an antiferromagnetic and temperature compensated timepiece balance spring, the method comprising: (10) selecting an amagnetic compensating alloy comprising, by mass percent, between and including the range limit values: from 21.0% to 25.0% of manganese, from 9.0% to 13.0% of nickel, from 6.0% to 15.0% of chromium, from 0.2% to 2.0% of beryllium, the remainder iron, the total of the nickel and the manganese being higher than or equal to 33.0%; (11) working said alloy to obtain a blank; (12) shaping said blank by casting, forging, wire drawing, rolling, drawing, or any combination thereof, to obtain a blank of spring wire; (13) winding said wire on a winder to obtain a spiral spring; and (14) subjecting said spiral spring to at least a heat setting treatment, by annealing at a temperature comprised between 540 C. and 650 C., for a duration of 30 to 200 minutes, to obtain a balance spring.

2. The method according to claim 1, wherein said alloy comprises, by mass percent, from 10.5% to 13.0% of the nickel.

3. The method according to claim 2, wherein said alloy comprises, by mass percent, from 11.0% to 13.0% of the nickel.

4. The method according to claim 1, wherein said alloy comprises, by mass percent, more than 7.5% to 15.0% of the chromium.

5. The method according to claim 4, wherein said alloy comprises, by mass percent, more than 10.5% to 15.0% of the chromium.

6. The method according to claim 1, wherein said alloy comprises, by mass percent, from 21.0% to 23.0% of the manganese.

7. The method according to claim 1, wherein said alloy comprises, by mass percent, a total of the nickel and the manganese of greater than or equal to 33.0%.

8. The method according to claim 7, wherein said alloy comprises, by mass percent, a total of the nickel and the manganese of greater than or equal to 34.0%.

9. The method according to claim 1, wherein said alloy comprises, by mass percent, a total of the nickel and the manganese of less than or equal to 35.5%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages of the invention will appear upon reading the following detailed description, with reference to the annexed drawings, in which the only FIG. 1 is a block diagram illustrating the steps of the method according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(2) The invention concerns a method for fabrication of an antiferromagnetic and temperature compensated timepiece balance spring.

(3) According to the invention, the method includes the following steps: (10) selecting an amagnetic compensating alloy, of the iron-chromium-nickel-manganese-beryllium type, comprising, by mass percent, between and including the range limit values: from 21.0% to 25.0% of manganese, from 9.0% to 13.0% of nickel, from 6.0% to 15.0% of chromium, from 0.2% to 2.0% of beryllium, the remainder iron, the total of nickel and manganese being higher than or equal to 33.0%, (11) working said alloy to obtain a blank, (12) shaping said blank by casting and/or forging and/or wire drawing and/or rolling and/or drawing, to obtain a blank of spring wire; (13) winding said wire on a winder to obtain a spiral spring, (14) subjecting said spiral spring to at least a heat setting treatment, by annealing at a temperature comprised between 540 C. and 650 C., for a duration of 30 to 200 minutes, to obtain a balance spring.

(4) In a particular implementation of this method, the alloy contains, by mass percent, from 10.5% to 13.0% of nickel.

(5) More particularly, this alloy contains, by mass percent, from 11.0% to 13.0% of nickel.

(6) In a particular implementation of this method, the alloy contains, by mass percent, more than 7.5% of chromium.

(7) More particularly, the alloy contains, by mass percent, more than 10.5% of chromium.

(8) In a particular implementation of the method, the alloy contains, by mass percent, from 21.0% to 23.0% of manganese.

(9) In a particular implementation of the method, the alloy contains, by mass percent, a total of nickel and manganese greater than or equal to 33.0%.

(10) More particularly, the alloy contains, by mass percent, a total of nickel and manganese greater than or equal to 34.0%.

(11) More particularly still, the alloy contains, by mass percent, a total of nickel and manganese less than or equal to 35.5%.