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 fabrication of an antiferromagnetic and temperature compensated timepiece balance spring, wherein said 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.

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

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

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

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

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

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

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

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

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] 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

[0014] The invention concerns a method for fabrication of an antiferromagnetic and temperature compensated timepiece balance spring.

[0015] According to the invention, the method includes the following steps:

[0016] (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: [0017] from 21.0% to 25.0% of manganese, [0018] from 9.0% to 13.0% of nickel, [0019] from 6.0% to 15.0% of chromium, [0020] from 0.2% to 2.0% of beryllium, [0021] the remainder iron, [0022] the total of nickel and manganese being higher than or equal to 33.0%,

[0023] (11) working said alloy to obtain a blank,

[0024] (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;

[0025] (13) winding said wire on a winder to obtain a spiral spring,

[0026] (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.

[0027] In a particular implementation of this method, the alloy contains, by mass percent, from 10.5% to 13.0% of nickel.

[0028] More particularly, this alloy contains, by mass percent, from 11.0% to 13.0% of nickel.

[0029] In a particular implementation of this method, the alloy contains, by mass percent, more than 7.5% of chromium.

[0030] More particularly, the alloy contains, by mass percent, more than 10.5% of chromium.

[0031] In a particular implementation of the method, the alloy contains, by mass percent, from 21.0% to 23.0% of manganese.

[0032] 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%.

[0033] More particularly, the alloy contains, by mass percent, a total of nickel and manganese greater than or equal to 34.0%.

[0034] More particularly still, the alloy contains, by mass percent, a total of nickel and manganese less than or equal to 35.5%.