EP3080666B1 - Process for making a bi-material shockproof system for a clock piece - Google Patents

Description

The present invention relates to the manufacture of a shock-absorbing bearing for an axis of a mobile of a timepiece. The shaft comprises a beam, comprising a support, said support being provided with a housing adapted to receive a suspended pivot system in which the tigeron is inserted.

The technical field of the invention is the technical field of fine mechanics.

BACKGROUND TECHNOLOGY

The present invention relates to the manufacture of bearings for timepieces, and more particularly of the type for damping shocks. Mechanical watch manufacturers have long designed numerous devices for absorbing the energy resulting from a shock by an axis of a mobile, by abutting against a wall of the hole of the base block through which it passes, while allowing a momentary movement of the tigeron before it is returned to its rest position under the action of a spring.

Requirement EP 2,605,086 describes a shock-absorbing bearing for an axis of a mobile of a timepiece, said axis comprising a tigeron, said bearing comprising a support provided with a housing adapted to receive a pivot system comprising a pivot module in which the tigeron is inserted and resilient means arranged to allow said pivot module to be suspended mounted and to exert on said pivot module at least one axial force. Only one pre-assembly step in which a diaphragm spring is overmoulded on the insert is described.

The figure 1 illustrates a shock absorbing device or shock absorbing bearing 1 comprising a support 2. This support has a housing 3 in which is arranged a pivot system 4 whose purpose is to damp, at least in part, the shocks suffered by the axis 5 of pendulum.

The pivot system 4 comprises elastic means 4a and a pivot module 4b. The elastic means are, in this example, in the form of a membrane. These elastic means are in the form of a base in the form of a disk comprising a lower face and an upper face and having a central orifice, the face bottom facing the bottom of the support that is to say the hole 6 in which the balance shaft terminated by a tigeron 5a passes. In the center of this disc is fixed the pivot module. This disc comprises, at its periphery, a peripheral flange 4c extending in an axial direction, that is to say in a direction tending to move away from the upper face. Preferably, this rim extends so that the surface of the horizontal plane to the disk increases as the height of the rim increases

The pivot system 4 is placed on the bottom of the support and the flange of the elastic means is supported for example on an outgrowth 2a of the support as visible in FIG. figure 1 .

Such a pivot system is made of plastic so that it can be manufactured using injection and molding techniques.

However, a disadvantage of such a shock absorber system is that it does not withstand shocks. Indeed, if the pivot does not break, the plastic is marked by the pivot. This marking of the plastic constituting the pivot system comes from the elastic part which has its Young's modulus which increases during the impact. However, the Young's modulus is also called modulus of elasticity (generally expressed in GPa) characterizes the resistance to the deformation of a material.

Thus, if the Young's modulus increases then the stress required for its deformation increases. Therefore, the resistance of the resilient means of the pivot system which is opposed to the pivot increases and therefore the force between the pivot and the bearing increases. This increase in force during a very short period of time may lead to the local appearance of a plastic deformation. This deformation can then cause a malfunction of the shock absorbing bearing.

SUMMARY OF THE INVENTION

The object of the invention is to overcome the disadvantages of the prior art by proposing to provide a shockproof timepiece system which has constant damping and friction characteristics.

For this purpose, the invention relates to the manufacture of a shock absorbing bearing according to claims 1 and 2. According to one embodiment, the pivoting means is made of a metallic material and comprises a recess in which is inserted an insert. made of a synthetic material and with which the tigeron cooperates.

In a variant, the insert is made of a polymeric material.

In a variant, the material of the insert is loaded.

In a variant, the polymer of the insert is chosen from the group comprising polyoxymethylene, polyamide, polyetheretherketone and polyphenylene sulphide.

In a variant, said pivoting means is a pellet comprising an annular part, a central part and elastic arms connecting the central part to the annular part, the central part comprising a recess so that an insert with which the pivot can cooperate to rotate freely.

In a variant, the pivoting means comprises three resilient arms angularly offset by an angle of 120 °.

In another variant, the insert comprises a hole for insertion of the pivot, this hole consisting of an opening having a first straight or rectangular portion followed by a trapezoidal portion.

1. a) Se munir du support et du moyen de pivotement comprenant un évidement puis placer le moyen de pivotement dans le logement du support;
2. b) Se munir de l'axe et de l'insert comprenant un trou permettant audit pivot de s'y insérer ;
3. c) Placer l'insert sur l'axe de sorte que le pivot de l'axe s'insère dans le trou de l'insert;
4. d) Monter le palier amortisseur de choc en manipulant l'axe de sorte que l'insert monté sur l'axe pénètre dans l'évidement.

The invention relates to a method of manufacturing a shock-absorbing bearing of a mobile of a timepiece, said axis comprising a tigeron and a pivot, said bearing comprising a support provided with a housing adapted to receive a suspended pivoting means, characterized in that said method comprises the following steps:

1. a) Bring the support and the pivoting means comprising a recess and then place the pivoting means in the housing of the support;
2. b) Provide the shaft and the insert comprising a hole allowing said pivot to be inserted therein;
3. c) Place the insert on the axis so that the pin of the pin fits into the hole of the insert;
4. d) Mount the shock absorbing bearing by manipulating the shaft so that the insert mounted on the shaft penetrates into the recess.

1. A) Se munir du support et du moyen de pivotement comprenant un évidement puis placer le moyen de pivotement dans le logement du support;
2. B) Se munir de l'axe et surmouler le pivot avec un matériau de sorte à former un insert;
3. C) Monter le palier amortisseur de choc en manipulant l'axe de sorte que l'insert sur l'axe pénètre dans l'évidement.

In a variant of the method, said method comprises the following steps:

1. A) Bring the support and the pivoting means comprising a recess and then place the pivoting means in the housing of the support;
2. B) Get the shaft and overmold the pivot with a material to form an insert;
3. C) Mount the shock absorbing bearing by manipulating the shaft so that the insert on the shaft enters the recess.

BRIEF DESCRIPTION OF THE FIGURES

• la figure 1 représente de manière schématique un système antichoc de pièce d'horlogerie de l'art antérieur;
• les figures 2 et 3 représentent de manière schématique un système antichoc de pièce d'horlogerie selon l'invention ;
• les figures 4 et 5 représentent de manière schématique un système antichoc de pièce d'horlogerie selon une variante de l'invention ;

The objects, advantages and characteristics of the anti-shock system according to the present invention will appear more clearly in the following detailed description of at least one embodiment of the invention given solely by way of nonlimiting example and illustrated by the appended drawings in which: :

• the figure 1 schematically shows a shockproof timepiece system of the prior art;
• the Figures 2 and 3 schematically represent a shockproof timepiece system according to the invention;
• the Figures 4 and 5 schematically represent a shockproof timepiece system according to a variant of the invention;

DETAILED DESCRIPTION

The present invention proceeds from the general inventive idea of providing a shock absorbing or shockproof system having greater reliability and providing better positioning.

The damping bearing or shockproof system 100 is shown in FIG. figure 2 , which illustrates a part of a timepiece provided with bearings according to the invention.

The damping bearing 100 represented at figure 2 comprises a frame comprising a support 103 in which a lower bearing 101 and an upper bearing 102 are mounted. These bearings 101, 102 are mounted in holes in said support 103. A mobile 105, which may be a rocker, is mounted on an axis 120 pivoting in these bearings. This axis 120 is provided at its two ends with tigers 121 carrying pivots 122.

The upper bearing 102 comprises an annular piece 127 in the form of a disc having an inner peripheral wall 128. This annular piece also comprises a flange 129 located on the disc surface and contiguous to the wall. This annular piece 127 is pierced with a central hole 130. The bearing 102 further comprises a pivoting means 126 'disposed in the housing formed by the peripheral wall 128 and the flange 129. The pivoting means 126' is placed on the rim 129 at its periphery so as to be suspended. This pivoting means 126 'is fixed to the annular piece 127, for example by driving, gluing, latching or held by a ring. There is therefore a space between the pivoting means 126 ', and the bottom of the housing formed by the peripheral wall 128 and the flange 129. The pivoting means are therefore in contact with the support 101 only at the level of the fixing with this one. The fact of being suspended allows the pivot means 126 'to be able to refocus perfectly following a displacement due to a shock.

The lower bearing 101 is identical in design to the upper bearing 102, that is to say that it comprises an annular piece 124 in the form of a disk having a peripheral wall. This annular piece also comprises a rim located on the disk surface and contiguous to the wall. This annular piece 124 is pierced with a central hole 125. The bearing 102 further comprises a pivoting means 126 disposed in the housing formed by the peripheral wall and the flange in a suspended manner. This pivoting means 126 is fixed to the annular piece 124 for example by driving, gluing, latching or held by a ring. In the present example, the dimensions of the lower bearing 101 will be smaller than those of the upper bearing 102 to show that the size of the bearing is easily adjustable and can be reduced. Of course, the dimensions of the upper bearing 102 and the lower bearing 101 may be identical.

However, the lower bearing 101 or greater 102, including a first non-visible variant can be arranged so that the pivot means 126, 126 'is directly fixed in the support 103 by driving or gluing or welding or brazing. Said bearing 101, 102 may comprise a piece in the form of a ring which serves to hold the pivoting means 126, 126 'and a piece in the form of a disc having a peripheral rim and pierced in its shape. center of a hole. This pierced disc shaped piece is used as a stop and its flange is used to provide a suspended system. The pivoting means 126, 126 'is thus held radially by the walls of the hole made in the support and axially by the annular piece and the disc-shaped piece pierced.

The pivoting means 126, 126 ', visible at the figure 3 are in the form of a pellet comprising a full annular portion 126a, a central portion 126b and elastic arms 126d. These arms 126d are wound substantially spirally so that they connect the central portion 126b to the annular portion 126a. Preferably, the pivoting means 126, 126 'comprise three arms 126d. The pivoting means 126 'of the upper bearing 102 are mounted in the annular part 127 of said upper bearing 102. The pivoting means 126, of the lower bearing 101 are mounted in the annular piece 124 inserted into the hole of the support 103.

Advantageously according to the invention, the central portion of the pivoting means 126, 126 'has a recess 126e in which an insert 1260 is placed. This insert 1260 is used so as to be provided with a hole 1261 in which the spindle of the shaft is inserted. This configuration makes it possible to have the pivoting means 126, 126 'in the form of a pellet comprising a full annular portion 126a, a central portion 126b and elastic arms 126d, which are made of a first material and the insert 1260 which is made of a second material. The wheel is then pivotally mounted being engaged at its pivots 122 in non-through holes 1261 of the insert 1260 and at its tigger 121 in the holes of the support 103.

This configuration allows the use of a specific material for the pivoting means 126, 126 'that is to say which is suitable for the damping function and a specific material for the insert that is to say a material suitable for a pivot function with a low coefficient of friction. The first material used for the pivot means 126, 126 'is a metallic material while the second material used for the insert 1260 is a synthetic material such as plastic. This plastic material may be a polymer selected from the group consisting of polyoxymethylene, polyamide, polyetheretherketone, polyphenylene sulfide.

The use of a metallic material for the elastic means that is to say the pivoting means 126, 126 'allows to have elastic means whose Young's modulus does not vary with the speed. As a result, the resistance of the resilient means opposite the pivot does not increase and the force between the pivot and the bearing remains stable.
In addition, the metals have a higher Young's modulus than for a plastic type material (for example the Young's modulus of Phynox (Cobalt Co + Chromium Cr + Nickel Ni + Molybdenum Mo) is 203 GPa, that of Titanium of 114 GPa, that of plexiglass of 2.38GPa and that of polyamide from 3 to 5 GPa). This difference in the value of the Young's modulus means that it is necessary to apply a higher stress for the metals so that they deform. Thus, at equal stress by the pivot, the pivoting means 126, 126 'of metal will move less than the pivoting means 126, 126' of plastic. Metals also enable proven assemblies that are difficult to reconcile with polymers, especially by driving (no significant creep), welding or brazing (temperature).

Another advantage of this choice of materials is that it makes it possible to have a more advantageous material for the pivot function. Indeed, the friction of a metal part on another metal part leads to heating and rapid wear of the pivot, lubrication is necessary to mitigate this heating.

With a 1260 insert in plastic material, the friction with a metal pivot is lower. In addition, there are plastics called self-lubricating. These plastics are known to have particularly favorable friction-related characteristics so that additional lubrication by oil is no longer necessary.

In a variant, the plastic material of the insert 1260 is a charged polymer. Under the general name of charge is meant any inert, mineral or vegetable substance which, added to a base polymer, makes it possible to appreciably modify its mechanical, electrical or thermal properties or its appearance.

In the event of an axial impact, the mobile 105 is subjected to a force that is proportional to the acceleration experienced. This force is transmitted to the bearings by means of the pivots 122. The effect of this force and to deform the elastic arms 126d of the pivoting means 126, 126 'until the axis 120 of the wheel comes to bear , through its tigger 121, against the wall of the holes 1261. In this case, the wheel is then stopped by the axis 120 which abuts on the support 127, 124 serving as a stop. Since the dimensions of the axis 120 are much larger than those of the pivots 122, the energy produced during the impact against the stop is thus transmitted to the axis 120 so as not to damage the pivots 122.

Preferably, the elastic arms 126d are dimensioned so that the tigger 121 come into contact with the annular parts as soon as an acceleration of about 500g is reached.

Preferably, the pivoting means 126, 126 'are formed by three curved arms 126d whose attachment points, respectively to the annular portion 126a and the central portion 126b, are angularly offset by 120 degrees. It is obvious that the elastic function could be ensured with a different number of arms, or with other forms.

It can also be understood that the insert 1260 comprises a hole 1261 conical so that the end of the tigeron can be inserted to allow a difference in amplitude between the different positions of the watch minimized. This conical 1261 hole known from the patent EP 2 142 965 consists of an opening having a first straight or rectangular portion that is to say having a straight or rectangular profile followed by a trapezoidal portion that is to say having a trapezoidal profile. The rounded tip of the pivot 122 is dimensioned so that its rounded surface can bear against the inclined edge of the trapezoidal profile portion.

In a variant of the invention visible to Figures 4 and 5 the invention also relates to a method for mounting such a shock absorbing bearing 100. Such a method consists in separately producing the pivoting means 126, 126 'and the insert 1260.

Then, the insert 1260 is placed on the axis 120 at its two ends of tibernums 121 carrying pivots 122. This arrangement of the insert 1260 serves to protect the pivots 122 so that the latter do not receive of shocks.

Finally, the system is mounted. For this, the pivoting means 126, 126 'are mounted in the supports 103. The axis 120 is then mounted between the lower bearing 101 and the upper bearing 102. For this, the axis 120 is manipulated so that each insert 1260 mounted on the pivots 122 is inserted by force into the recess 126e of the pivot means 126, 126 'to accommodate them.

1. a) Se munir du support 102, 103 et du moyen de pivotement 126, 126' comprenant un évidement 126e puis placer le moyen de pivotement 126, 126' dans le logement du support 102, 103;
2. b) Se munir de l'axe 120 et de l'insert 1260 comprenant un trou 1261 permettant audit pivot 122 de s'y insérer;
3. c) Placer l'insert 1260 sur l'axe 120 de sorte que le pivot 122 de l'axe s'insère dans l'insert 1260;
4. d) Monter le palier amortisseur de choc en manipulant l'axe 120 de sorte que l'insert 1260 sur l'axe 120 pénètre dans l'évidement 126e.

In summary, the method consists of:

1. a) Bring the support 102, 103 and the pivot means 126, 126 'comprising a recess 126e and then place the pivoting means 126, 126' in the housing of the support 102, 103;
2. b) Bring the axis 120 and the insert 1260 comprising a hole 1261 allowing said pivot 122 to be inserted therein;
3. c) Place the insert 1260 on the axis 120 so that the pivot 122 of the axis fits into the insert 1260;
4. d) Mount the shock absorbing bearing by manipulating the shaft 120 so that the insert 1260 on the shaft 120 enters the recess 126e.

1. A) Se munir du support 102, 103 et du moyen de pivotement 126, 126' comprenant un évidement 126e puis placer le moyen de pivotement 126, 126' dans le logement du support 102, 103;
2. B) Se munir de l'axe 120 et surmouler le pivot 122 avec un matériau de sorte à former un insert 1260;
3. C) Monter le palier amortisseur de choc en manipulant l'axe 120 de sorte que l'insert 1260 sur l'axe 120 pénètre dans l'évidement 126e.

In a variant, the inserts 1260 are directly made on the axis 120. For this, the pivots 122 of the axis 120 are placed in the molds used to make the inserts 1260. The synthetic material used for the inserts 1260 is then injected. in the molds to form the inserts 1260. This variant is advantageous because it allows to have the inserts 1260 and the pivots 122 of the axis 120 which cooperate perfectly. The method therefore consists of:

1. A) Bring the support 102, 103 and the pivot means 126, 126 'comprising a recess 126e and then place the pivoting means 126, 126' in the housing of the support 102, 103;
2. B) Bring the axis 120 and overmould the pivot 122 with a material so as to form an insert 1260;
3. C) Mount the shock absorbing bearing by manipulating the shaft 120 so that the insert 1260 on the shaft 120 enters the recess 126e.

It will be understood that various modifications and / or improvements and / or combinations obvious to those skilled in the art can be made to the various embodiments of the invention set out above without departing from the scope of the invention defined by the appended claims.

Claims (3)

1. Method for fabrication of a shock absorber bearing for an arbor of a timepiece mobile part, said arbor (120) including a pivot-shank (121) and a pivot (122), said bearing including a support (102, 103) provided with a housing arranged to receive a suspended pivot means (126, 126'), characterized in that said method includes the following steps:

   a) Taking the support (102, 103) and the pivot means (126, 126') comprising a recess (126e) and then placing the pivot means (126, 126') inside the housing in the support (102, 103).

   b) Taking the arbor (120) and the insert (1260) comprising a hole (1261) for insertion of said pivot (122) therein.

   c) Placing the insert (1260) on the arbor (120) so that the arbor pivot (122) is inserted inside the hole (1261) in the insert (1260).

   d) Mounting the shock absorber bearing by manipulating the arbor (120) so that the insert (1260) mounted on the arbor (120) penetrates the recess (126e).
2. Method for fabrication of a shock absorber bearing for an arbour of a timepiece mobile part, said arbor (120) including a pivot-shank (121) and a pivot (122), said bearing including a support (102, 103) provided with a housing arranged to receive a suspended pivot means (126, 126'), characterized in that said method includes the following steps:

   a) Taking the support (102, 103) and the pivot means (126, 126') comprising a recess (126e) and then placing the pivot means (126, 126') inside the housing in the support (102, 103).

   b) Taking the arbor (120) and over moulding the pivot (122) with a material so as to form an insert (1260).

   c) Mounting the shock absorber bearing by manipulating the arbor (120) so that the insert (1260) on the arbor (120) penetrates the recess (126e).
3. Method for fabrication of a shock absorber bearing according to claim 1 or 2, characterized in that the pivot means (126, 126') is made of a metallic material and in that the insert (1260) is made of synthetic material.

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