Part for a timepiece movement

Patent metadata

Field	Value
Publication number	US-9182742-B2
Application number	US-201414154673-A
Country	US
Kind code	B2
Filing date	Jan 14, 2014
Priority date	Jan 17, 2013
Publication date	Nov 10, 2015
Grant date	Nov 10, 2015

Abstract

A metal pivot pin for a timepiece movement includes at least one pivot at at least one of ends thereof, the metal is an austenitic steel, an austenitic cobalt alloy or an austenitic nickel alloy to limit sensitivity of the pin to magnetic fields, and at least an outer surface of the at least one pivot is hardened to a predetermined depth relative to a core of the pin. A method of fabricating a pivot pin includes forming the pivot pin from a base of austenitic steel, an austenitic cobalt alloy or an austenitic nickel alloy, to limit sensitivity of the pin to magnetic fields, including at least one pivot at one end of the pin, and diffusing atoms to a predetermined depth at least on an outer surface of said at least one pivot to harden the pivot in main areas of stress while maintaining a high roughness.

First claim

What is claimed is:

1. A method of fabricating a pivot pin comprising:
a) forming the pivot pin from a base of an austenitic cobalt alloy or an austenitic nickel alloy, to limit sensitivity of the pin to magnetic fields, including at least one pivot at one end of the pin; and
b) diffusing atoms to a predetermined depth at least on an outer surface of said at least one pivot in order to harden the pivot in main areas of stress while maintaining a high roughness.

2. The method according to claim 1 , wherein the predetermined depth represents between 5% and 40% of a total diameter of the at least one pivot.

3. The method according to claim 2 , wherein the diffusing includes diffusing atoms of at least one chemical element.

4. The method according to claim 1 , wherein the diffusing includes diffusing atoms of at least one chemical element.

5. The method according to claim 3 , wherein the atoms include at least one non-metal.

6. The method according to claim 4 , wherein said at least one non-metal is at least one of nitrogen and carbon.

7. The method according to claim 1 , wherein the diffusing includes a thermochemical diffusion treatment.

8. The method according to claim 1 , wherein the diffusing includes an ionic implantation process which may or may not be followed by a diffusion treatment.

9. The method according to claim 1 , wherein the at least one pivot undergoes a rolling/polishing after the diffusing.

10. A method of fabricating a pivot pin comprising:
a) forming the pivot pin from a base of a metal selected from among a group comprising austenitic chromium-nickel stainless steels including at least 16.5% Cr and 10% Ni, austenitic cobalt steels including at least 39% cobalt, and austenitic nickel steels including at least 33% nickel, to limit sensitivity of the pin to magnetic fields, including at least one pivot at one end of the pin; and
b) diffusing atoms to a predetermined depth at least on an outer surface of said at least one pivot in order to harden the pivot in main areas of stress while maintaining a high roughness.

11. The method according to claim 10 , wherein the metal forming the pin is selected from among a group including X2CrNiMo17-12-2+Su+Cu austenitic steel, K13C20N16Fe15D7 austenitic cobalt alloy, and the austenitic nickel alloy having a composition of 35% Ni, 20% Cr, 10% Mo, 33% Co and a remainder comprised of additives.

Assignees

• Omega Sa
• Omega Sa

Inventors

• Von Gruenigen Cedric
• Charbon Christian
• Verardo Marco

Classifications

• G04B1/16

  Barrels; Arbors; Barrel axles (arrangements facilitating the removal of the mainspring G04B33/14) · CPC title

• Y10T29/49

  Method of mechanical manufacture · CPC title

• G04B1/04

  Mechanisms in which the clockwork acts as the driving weight · CPC title

• G04B13/026

  Physics · mapped topic

• G04B15/14 Primary

  Component parts or constructional details, e.g. construction of the lever or the escape wheel {(assembly and manufacture of the spring G04B1/145; assembly and manufacture of components, e.g. pinions, spindles G04B13/02; lubrication of clockwork bearings G04B31/008; oils for clockwork bearings in general G04B31/08)} · CPC title