Classifications

• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B1/00—Driving mechanisms
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B1/00—Driving mechanisms
  • G04B1/10—Driving mechanisms with mainspring
  • G04B1/16—Barrels; Arbors; Barrel axles
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B13/00—Gearwork
  • G04B13/02—Wheels; Pinions; Spindles; Pivots
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B15/00—Escapements
  • G04B15/14—Component parts or constructional details, e.g. construction of the lever or the escape wheel
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B17/00—Mechanisms for stabilising frequency
  • G04B17/32—Component parts or constructional details, e.g. collet, stud, virole or piton
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B43/00—Protecting clockworks by shields or other means against external influences, e.g. magnetic fields
  • G04B43/007—Antimagnetic alloys
• • G—PHYSICS
  • G04—HOROLOGY
  • G04D—APPARATUS OR TOOLS SPECIALLY DESIGNED FOR MAKING OR MAINTAINING CLOCKS OR WATCHES
  • G04D3/00—Watchmakers' or watch-repairers' machines or tools for working materials
  • G04D3/0069—Watchmakers' or watch-repairers' machines or tools for working materials for working with non-mechanical means, e.g. chemical, electrochemical, metallising, vapourising; with electron beams, laser beams

Definitions

• the invention relates to a part for a watch movement and in particular to a non-magnetic pivot axis for a mechanical watch movement and more particularly to a non-magnetic balance shaft, anchor stem and escapement pinion.
• the manufacture of a watch pivot shaft consists, starting from a hardenable steel bar, of carrying out bar turning operations to define different active surfaces (bearing, shoulder, pivots, etc.) and then subjecting the bar turned shaft to heat treatment operations including at least one quenching to improve the hardness of the shaft and one or more tempering operations to improve its toughness.
• the heat treatment operations are followed by a rolling operation of the pivots of the shafts, an operation consisting of polishing the pivots to bring them to the required dimensions. During the rolling operation, the hardness and roughness of the pivots are further improved. It should be noted that this rolling operation is very difficult or even impossible to carry out with most materials whose hardness is low, i.e. less than 600HV.
• Pivot shafts such as balance shafts, typically used in mechanical watch movements are made from free-cutting steel grades, which are typically martensitic carbon steels containing lead and manganese sulfides to improve their machinability.
• This type of material has the advantage of being easily machinable, in particular of being suitable for bar turning and presents, after quenching and tempering treatments, very interesting high mechanical properties. for the production of watch pivot axes.
• These steels have, in particular, high wear resistance and hardness after heat treatment.
• the hardness of the pivots of an axis made of 20 AP steel can reach a hardness exceeding 700 HV after heat treatment and rolling.
• this type of material has the disadvantage of being magnetic and of being able to disturb the running of a watch after being subjected to a magnetic field, particularly when this material is used for the production of a balance staff cooperating with a balance spring made of ferromagnetic material. This phenomenon is well known to those skilled in the art. It should also be noted that these martensitic steels are also sensitive to corrosion.
• austenitic stainless steels which have the particularity of being non-magnetic, that is to say of the paramagnetic or diamagnetic or antiferromagnetic type.
• these austenitic steels have a crystallographic structure which does not allow them to be hardened and to achieve hardnesses and therefore wear resistances compatible with the requirements for the production of watch pivot axes.
• One way to increase the hardness of these steels is work hardening, however this hardening operation does not allow hardnesses greater than 500 HV to be obtained. Consequently, in the context of parts requiring high resistance to wear by friction and which must have pivots with little or no risk of deformation, the use of this type of steel remains limited.
• the pivots can be made of this same material or of steel. It is also possible to provide for the deposition of an additional layer applied galvanically, chemically, or from the gas phase (for example in Cr, Rh, etc.). This additional layer presents a significant risk of delamination.
• This document also describes a balance shaft made entirely of hardenable bronze. However, no information is given on the manufacturing process of the pivots.
• a part made of hardenable bronze has a hardness of less than 450 HV. Such hardness appears to the skilled person to be insufficient for rolling treatment.
• the aim of the present invention is to overcome all or part of the drawbacks mentioned above by proposing a pivot axis which makes it possible both to limit sensitivity to magnetic fields and to obtain improved hardness compatible with the requirements of resistance to wear and shocks in the watchmaking field.
• the invention also aims to provide a non-magnetic pivot axis having improved corrosion resistance.
• the invention also aims to provide a non-magnetic pivot axis which can be manufactured simply and economically.
• the invention relates to a pivot axis for a watch movement comprising at least one metal pivot at at least one of its ends according to the characteristics of claim 1.
• the pivot shaft can combine advantages such as low sensitivity to magnetic fields, and in the main stress areas, hardness, in addition to good corrosion resistance while maintaining good general toughness. Furthermore, the use of such a non-magnetic copper alloy is advantageous insofar as they have good machinability.
• the predetermined depth represents between 5% and 40% of the total diameter of the pivot, typically between 5 and 35 microns.
• the deep-hardened external surface comprises diffused atoms of at least one chemical element.
• non-magnetic material means a paramagnetic or diamagnetic or antiferromagnetic material, the magnetic permeability of which is less than or equal to 1.01.
• the invention relates to a part for a watch movement and in particular to a non-magnetic pivot axis for a mechanical watch movement.
• a balance shaft 1 which comprises a plurality of sections 2 of different diameters, preferably formed by turning or any other machining technique by chip removal, and conventionally defining bearing surfaces 2a and shoulders 2b arranged between two end portions defining two pivots 3. These pivots are intended to each pivot in a bearing, typically in an orifice of a stone or ruby.
• the metal 4 of the pivot 3 is a non-magnetic copper alloy in order to advantageously limit its sensitivity to magnetic fields.
• at least the external surface 5 of the pivots 3 ( Figure 2 ) is hardened in depth relative to the rest of the pivot 3 according to a predetermined depth in order to offer, advantageously according to the invention, a hardness high at the level of said external surface while maintaining high toughness.
• the deep hardened external surface of the pivots 3 has a hardness greater than 600 HV.
• the non-magnetic copper alloy is chosen from the group comprising a brass (Cu-Zn) or a special brass (Cu-Zn with Al and/or Si and/or Mn), a copper-beryllium, a bronze (Cu-Sn), an aluminum bronze, a copper-aluminum (optionally comprising Ni and/or Fe), a copper-nickel, a nickel silver (Cu-Ni-Zn), a copper-nickel-tin, a copper-nickel-silicon, a copper-nickel-phosphorus, a copper-titanium, the proportions of the different elements of the alloys being chosen to give them non-magnetic properties as well as good machinability.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Metallurgy (AREA)
• Optics & Photonics (AREA)
• Plasma & Fusion (AREA)
• Sliding-Contact Bearings (AREA)
• Heat Treatment Of Articles (AREA)
• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
• Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)
• Electric Clocks (AREA)

Priority Applications (8)

Applications Claiming Priority (1)

Publications (2)

Family

ID=56464141

Family Applications (1)

Country Status (6)

Families Citing this family (8)

Family Cites Families (22)

• 2016
  • 2016-07-19 EP EP16180223.6A patent/EP3273303B1/fr active Active
• 2017
  • 2017-07-11 JP JP2017135239A patent/JP6857096B2/ja active Active
  • 2017-07-17 US US15/651,318 patent/US20180024500A1/en not_active Abandoned
  • 2017-07-18 CN CN202111361414.3A patent/CN114035413A/zh active Pending
  • 2017-07-18 RU RU2017125552A patent/RU2752292C2/ru active
  • 2017-07-18 CN CN201710584248.0A patent/CN107632509A/zh active Pending
• 2018
  • 2018-07-06 HK HK18108784.3A patent/HK1249199A1/zh unknown
• 2019
  • 2019-06-26 JP JP2019118342A patent/JP7018040B2/ja active Active

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