• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a pivot axis having a pivot (3) made of metal at each of its ends. The metal is a non-magnetic aluminum alloy (4) in order to limit its sensitivity to magnetic fields and at least the outer surface (5) of one of the two pivots (3) is hardened in depth with respect to the center of the axis at a predetermined depth to harden the pivot (s) (3). The invention also relates to a movement for a timepiece comprising such an axis and a manufacturing method of said axis.
    公开号:CH712720A2
    申请号:CH00929/16
    申请日:2016-07-19
    公开日:2018-01-31
    发明作者:Charbon Christian；Fussinger Alexandre；Verardo Marco
    申请人:Nivarox-Far S A；
    IPC主号:
    专利说明:

    Description
    FIELD OF THE INVENTION [0001] The invention relates to a piece for a watch movement and in particular to an amagné-tick pivoting axis for a mechanical clockwork movement and more particularly to a balance shaft, a rod of anchor and a non-magnetic exhaust pinion.
    BACKGROUND OF THE INVENTION [0002] The manufacture of a clockwise pivoting pin consists, from a hardenable steel bar, of performing bar turning operations to define different active surfaces (bearing, shoulder, pivots, etc.). and then subjecting the neckline to heat treatment operations comprising at least one quenching to improve the hardness of the axis and one or more incomes to improve toughness. The heat treatment operations are followed by a rolling operation of the pivots of the axes, an operation consisting in polishing the pivots to bring them to the required dimensions. During the rolling operation the hardness as well as the roughness of the pivots are further improved. Note that this rolling operation is very difficult or impossible to achieve with most materials whose hardness is low, that is to say less than 600 HV.
    The pivot axes, for example the balance axes, conventionally used in mechanical watch movements are made in grades of free cutting steels which are generally mar-tensitic carbon steels including lead and sulphides. of manganese to improve their machinability. A steel of this type referred to as AP is typically used for these applications.
    This type of material has the advantage of being easily machinable, in particular to be able to cut and has, after quenching and tempering treatments, high mechanical properties very interesting for the realization of axes of pivoting watchmakers. In particular, these steels exhibit high wear resistance and hardness after heat treatment. Typically the hardness of the pivots of an axis made of steel AP may reach a hardness exceeding 700 HV after heat treatment and rolling.
    Although providing satisfactory mechanical properties for horological applications described above, this type of material has the disadvantage of being magnetic and can disrupt the running of a watch after being subjected to a magnetic field, and in particular when this material is used for producing a balance shaft cooperating with a balance spring 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 susceptible to corrosion.
    Attempts to overcome these disadvantages have been conducted with austenitic stainless steels which have the distinction of being non-magnetic ie paramagnetic or diamagnetic or antiferromagnetic type. However, these austenitic steels have a crystallographic structure that does not allow them to be hardened and to reach hardnesses and therefore wear resistances that are compatible with the requirements required for the realization of clockwise pivot axes. One way to increase the hardness of these steels is work hardening, however this hardening operation does not allow to obtain hardnesses greater than 500 HV. Therefore, in the context of parts requiring high resistance to frictional wear and having pivots having little or no risk of deformation, the use of this type of steel remains limited.
    Another approach to try to overcome these disadvantages has been to deposit on the pivot axes of the hard layers of materials such as the amorphous carbon known as English diamond carbon (DLC). However, there have been significant risks of delamination of the hard layer and therefore the formation of debris that can circulate inside the watch movement and come to disrupt the operation of the latter, which is not satisfactory.
    A similar approach, described in patent FR 2015 873, provides for making a balance shaft at least the main part is made of certain non-magnetic materials. The pivots can be in the same material or steel. It is also possible to provide 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 rocker shaft made entirely of curable bronze. However, no information is given on the manufacturing process of the pivots. In addition, a piece made of curable bronze has a hardness less than 450 HV. Such hardness appears to those skilled in the art as insufficient to perform a rolling treatment.
    EP 2 757 423 also discloses pivoting pins made of a cobalt or nickel alloy of the austenitic type and having an outer surface hardened to a certain depth. However, such alloys can be difficult to machine by chip removal. In addition, they are relatively expensive because of the high price of nickel and cobalt. SUMMARY OF THE INVENTION [0010] The object of the present invention is to overcome all or part of the aforementioned drawbacks by proposing a pivot axis making it possible at the same time to limit the sensitivity to magnetic fields and to obtain an improved hardness compatible with the requirements of resistance to wear and shock in the watchmaking field.
    The invention also aims to provide a nonmagnetic pivot axis having improved corrosion resistance.
    The invention also aims to provide a non-magnetic pivot axis that can be manufactured simply and economically.
    For this purpose, 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 invention, the metal is a non-magnetic aluminum alloy in order to limit its sensitivity to magnetic fields, and at least the outer surface of said at least one pivot is hardened in depth relative to the core of the axis according to a predetermined depth.
    Therefore, a surface area or the entire surface of the axis is hardened, that is to say that the heart of the axis can remain little or no change. By this selective hardening of portions of the axis, the pivot axis can accumulate advantages such as low sensitivity to magnetic fields, and in the main stress zones, hardness, in addition to good corrosion resistance while maintaining a good general tenacity. Moreover, the use of such a nonmagnetic aluminum alloy is advantageous insofar as the latter have good machinability.
    According to other advantageous features of the invention: the predetermined depth is between 5% and 40% of the total diameter of the pivot, typically between 5 and 35 microns; the deep-hardened outer surface comprises diffused atoms of at least one chemical element; the deep-hardened outer surface has a hardness of preferably greater than 600 HV.
    In addition, the invention relates to a watch movement comprising a pivot axis according to one of the preceding variants, and in particular a balance shaft, an anchor rod and / or a pinion of exhaust comprising an axis as defined above.
    Finally, the invention relates to a method of manufacturing a pivot axis comprising the following steps: a) forming, preferably by bar turning or any other machining process by removing chips, a pivot axis having at least one metal pivot at at least one of its ends, said metal being a non-magnetic aluminum alloy, to limit its sensitivity to magnetic fields; b) diffusing atoms by an ion implantation process at a predetermined depth at least in the outer surface of said pivot to deeply harden the pivot axis at the main stress zones while maintaining high toughness.
    Therefore, by diffusion of atoms in the aluminum alloy, a surface area or the entire surface of the pivots is cured without having to deposit a second material over the pivots. Indeed, the hardening is carried out directly in the material of the pivot axis which advantageously allows according to the invention to avoid any subsequent delamination as may occur in the case of the deposition of a hard layer on the axis .
    According to other advantageous features of the invention; the predetermined depth represents between 5% and 40% of the total diameter of the pivot; the atoms comprise at least one chemical element; the pivots are rolled or polished after step b).
    BRIEF DESCRIPTION OF THE DRAWINGS [0021] Other features and advantages will clearly show the description which is given below, by way of indication and in no way limitative, with reference to the accompanying drawings, in which: FIG. 1 is a representation of a pivot axis according to the invention; and FIG. 2 is a partial section of a rocker arm pivot according to the invention after the dif fusion treatment operation by ion implantation and after the rolling or polishing operation.
    DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present description, the term "non-magnetic" material means a paramagnetic or diamagnetic or antiferromagnetic material whose magnetic permeability is less than or equal to 1.01.
    [0023] An aluminum alloy is an alloy containing at least 50% by weight of aluminum.
    The invention relates to a piece for a watch movement and in particular to a non-magnetic pivoting axis for a mechanical clockwork movement.
    The invention will be described below in the context of an application to a non-magnetic balance shaft 1. Of course, other types of clockwise pivot axes are possible, such as for example axes of watchmakers, typically exhaust gears, or anchor rods. The parts of this type have at the body diameters preferably less than 2 mm, and pivots of smaller diameter preferably 0.2 mm, with an accuracy of a few microns.
    Referring to FIG. 1 can be seen a balance shaft 1 according to the invention which comprises a plurality of sections 2 of different diameters, preferably formed by bar turning or any other machining process by chip removal, and classically defining spans 2a and shoulders 2b arranged between two end portions defining two pivots 3. These pivots are intended to each rotate in a bearing, typically in a hole of a stone or ruby.
    With the magnetism induced by the objects encountered on a daily basis, it is important to limit the sensitivity of the balance shaft 1 under penalty of influencing the operation of the timepiece in which it is incorporated.
    Surprisingly, the invention solves both problems at the same time without compromise and providing other benefits. Thus, the metal 4 of the pivot 3 is a non-magnetic aluminum alloy in order to advantageously limit its sensitivity to magnetic fields. In addition, at least the outer surface 5 of the pivots 3 (FIG 2) is hardened in depth relative to the remainder of the pivot 3 to a predetermined depth advantageously by means of an ion implantation process in order to offer, advantageously according to the invention, a high hardness at said outer surface while maintaining a high tenacity.
    Indeed, according to the invention, the outer surface hardened in depth pivots 3 has a hardness greater than 600 HV.
    Preferably, the non-magnetic aluminum alloy is chosen from the group comprising an aluminum-copper-lead alloy, an aluminum-silicon-magnesium-manganese alloy, an aluminum-zinc-magnesium-copper alloy, the proportions of different elements of the alloys being chosen to give them non-magnetic properties and good machinability.
    For example, the non-magnetic aluminum alloys used in the present invention, designated according to DIN EN-573-3, are: EN AW-2007 of formula AICu4PbMgMn (designated Avional Pb118) EN AW-2011 of formula AICu6BiPb ( designated Decoltal 500) EN AW-6082 of formula AISMMgMn (designated Anticorodal 100/112) EN AW-7075 of formula AIZn5.5MgCu (designated Perunal 215).
    The aluminum alloy 7449 of formula AIZn8Mg2Cu can also be used.
    The composition values are given as a percentage by weight. The elements without indication of composition value are either the remainder (Aluminum) or elements for which the percentage in the composition is less than 1% by weight.
    Of course, other alloys based on nonmagnetic aluminum are possible since the proportion of their constituents gives them non-magnetic properties and good machinability.
    It has been shown empirically that a curing depth of between 5% and 40% of the total diameter of the pivots 3 is sufficient for application to a balance shaft. For example, if the radius d / 2 is 50 pm, the depth of hardening is preferably around 15 pm around the pivots 3. Of course, depending on the application, a different depth of hardening of between 5% and 80% of the total diameter d can be provided.
    Preferably according to the invention, the outer surface 5 hardened in depth pivots 3 comprises diffused atoms of at least one chemical element. For example, this chemical element may be a non-metal such as nitrogen, argon and / or helium. Indeed, as explained below, by interstitial supersaturation of atoms in the nonmagnetic aluminum alloy 4, a superficial zone 5 is cured in depth without having to deposit a second material over the pivots 3. In fact, the hardening is carried out directly in the material 4 of the pivots 3 which advantageously allows according to the invention to avoid any subsequent delamination during use. Therefore, the outer surface 5 of the pivot 3 comprises a hard surface layer but has no additional hardening layer deposited directly on said outer surface 5. It is obvious that other layers having no hardening function can to be deposited. Thus, it is possible to deposit on the outer surface of the pivot a lubrication layer for example.
    权利要求:
    Claims (15)
    [1]
    Pivoting axis (1) for a watch movement comprising at least one metal pivot (3) at at least one of its ends, characterized in that the metal is a non-magnetic aluminum alloy in order to limit its sensitivity to magnetic fields and in that at least the outer surface (5) of said pivot (3) is hardened in depth with respect to the heart of the axis to a predetermined depth.
    [2]
    2. Pivot axis (1) according to claim 1, characterized in that the predetermined depth is between 5% and 40% of the total diameter (d) of the pivot (3).
    [3]
    3. Pivot axis (1) according to one of claims 1 or 2, characterized in that the outer surface (5) cured in depth comprises diffused atoms of at least one chemical element.
    [4]
    4. Pivot axis (1) according to one of the preceding claims, characterized in that the outer surface (5) hardened in depth has a hardness greater than 600 HV.
    [5]
    5. Pivot axis (1) according to one of the preceding claims, characterized in that the ama-gnetic aluminum alloy is selected from the group comprising an aluminum-copper-lead alloy, an aluminum-silicon-magnesium alloy -Manganese, an aluminum-zinc-magnesium-copper alloy.
    [6]
    6. Pivot axis (1) according to one of the preceding claims, characterized in that said outer surface (5) of said pivot (3) has no curing layer deposited directly on said outer surface.
    [7]
    7. Pivot axis (1) according to one of the preceding claims, characterized in that at least the outer surface (5) of said pivot (3) is rolled.
    [8]
    8. Pivot axis (1) according to one of the preceding claims, characterized in that it comprises two pivots.
    [9]
    9. Movement for timepiece, characterized in that it comprises a pivot axis (1) according to one of the preceding claims.
    [10]
    10. Movement for a timepiece characterized in that it comprises a rocker shaft (1), an anchor rod and / or an exhaust pinion comprising an axis according to one of claims 1 to 10.
    [11]
    11. A method of manufacturing a pivot axis (1) for a watch movement comprising the following steps: a) forming a pivot axis (1) comprising at least one pivot (3) made of metal at at least one of its ends, said metal being a non-magnetic aluminum alloy to limit its sensitivity to magnetic fields; b) diffusing atoms by an ion implantation process at a predetermined depth at least in the outer surface (5) of said pivot (3) in order to deepen the pivot axis (1) at the main stress zones while keeping a high tenacity.
    [12]
    12. The method of claim 12, characterized in that the predetermined depth is between 5% and 40% of the total diameter (d) of the pivot (3).
    [13]
    13. Method according to one of claims 12 or 13, characterized in that the diffusion step comprises the diffusion of atoms of at least one chemical element.
    [14]
    14. Method according to one of claims 12 to 15, characterized in that it comprises no deposition step, directly on the outer surface (5) of the pivot (3), a hardening layer.
    [15]
    15. Method according to one of claims 12 to 16, characterized in that the pivot (3) undergoes a rolling / po-smoothing operation after step b).
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    同族专利:
    公开号 | 公开日
    CH712720B1|2020-12-15|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    CH00929/16A|CH712720B1|2016-07-19|2016-07-19|Pivot pin for clockwork movement.|CH00929/16A| CH712720B1|2016-07-19|2016-07-19|Pivot pin for clockwork movement.|
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