CH714775B1 - Piton for fixing a spiral spring of a watch movement and methods of manufacturing such a stud. - Google Patents

Abstract

The invention relates to a stud for fixing by means of an adhesive pad (16) a free end (18) of a last turn outside of a spiral spring for a watch movement, this stud (2) comprising a base (4) which extends in a plane, a first arm (6) and a second arm (8) which extend from this plane and which are free at their end opposite to the base (4), the first and second arms (6, 8) being separated from each other by a gap in which is housed the free end (18) of the last turn outside the spring spiral which is trapped in the hardened adhesive pad (16), at least one of the first and second arms (6, 8) being provided with a stop means arranged to prevent the glue pad (16) cured in which is trapped the free end (18) of the last turn outside the spiral spring to disengage the gap in which is housed this plo t glue (16) hardened when this glue pad (16) no longer adheres to the stud (2). The invention also relates to two methods of manufacturing such a piton.

Description

CH 714 775 B1

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a stud for fixing a spiral spring of a clockwork movement. More specifically, the present invention relates to a stud in which a last turn outside of a spiral spring of a clockwork movement is fixed by gluing. The invention also relates to a method of manufacturing such a peak.

Technological background of the invention In the field of watchmaking, a spiral spring associated with a pendulum forms a time base for mechanical timepieces. As a first approach, the spiral spring is in the form of a very thin spring wound in concentric turns. A first end of the spiral spring, called the first coil on the inside, is fixed to a ferrule, and a second end of the spiral spring, called the last coil on the outside, is fixed to a piton.

More specifically, the time base for mechanical timepieces, also called an oscillating system, includes a balance spring-balance spring and an escapement pair. The pendulum consists of a pendulum axis pivoted between a first and a second bearing and connected to a pendulum clamp by means of radial arms. The spiral spring is fixed via its first turn inside the pendulum axis, for example by means of a ferrule. The spiral spring is fixed via its last coil on the outside to a point of attachment formed by a stud carried by a stud holder if necessary. The exhaust, meanwhile, includes a double tray system consisting of a large tray that carries a tray pin and a small tray in which is provided a notch. The escapement also includes an anchor, an anchor axis of which is pivoted between a first and a second bearing. The anchor consists of a rod that connects a fork to an input arm and an output arm. The fork consists of an input horn and an output horn between which a stinger extends. The travel of the fork is limited by an entry limiting pin and an exit limiting pin which can be made in one piece with an anchor bridge. The input arm and the output arm respectively carry an input pallet and an output pallet. Finally, the anchor cooperates with an escapement wheel comprising an escapement wheel axle pivoted between a first and a second bearing.

The spiral spring takes the form of a spiral wound in a horizontal plane, parallel to the plane of the clockwork movement, it only serves one function: once associated with a pendulum, it must rotate in one direction, then in the other, that is to say oscillate around its equilibrium position at a frequency as constant as possible. It is said that the spiral spring breathes. However, everything contributes to preventing a spiral spring from always oscillating at the same frequency. The spiral spring must in particular resist oxidation and magnetism which stick the turns together and stop the watch. The influence of atmospheric pressure, on the other hand, is weak. For a long time, it was the temperature that was the heart of the problem, because the heat expands the metal, while the cold shrinks it. The spiral spring must also be elastic to deform and still always regain its shape.

The material used for the production of spiral springs is usually steel. Ductile, such an alloy must resist corrosion. Recent developments suggest making spiral springs out of silicon. Silicon hairsprings, especially because they are insensitive to magnetism, are more precise than their steel predecessors. On the other hand, their cost price is higher and they are more difficult to assemble.

A spiral spring must be isochronous. No matter how far the spiral spring rotates, it should always take the same time to oscillate. If the spiral spring contracts only a few degrees, it accumulates little energy and slowly returns to its equilibrium position. If the spiral spring is moved far from its equilibrium position, it goes very quickly in the opposite direction. The important thing is that these two trips are made in the same duration. The underlying idea is that the energy available to the spiral spring is not constant and that it must still work whether the watch is fully wound or whether it is in its last hours of power reserve.

Due to their small dimensions, the spiral springs are difficult to assemble. However, the way in which the two ends of a spiral spring are fixed also greatly influences the precision of the movement of the watch movement. In most mechanical watch movements, the two ends of the spiral spring are inserted into a drilled part and are immobilized by means of a pin manually force-fitted using pliers. There can then occur a slight rotation of the spiral spring, which is detrimental to the precision of the movement. To overcome this problem, the French watch manufacturer Lip, in the 1960s, proposed to stick a spiral spring with a grain of hot-melt glue, that is to say a glue hard at room temperature, but melting under the action of heat.

However, even the technique of gluing the end of the spiral springs using hot-melt adhesive has shown its limits. It has in fact been observed that due to its viscosity, the hot-melt adhesive, while melting, exerts by capillarity a tensile force on the spiral spring and can press the end of the spiral spring against the walls of the piton in which this end is engaged. The resulting deformation of the spiral spring induces in it mechanical stresses which are very detrimental to the regularity of its progress.

To remedy these problems, the Applicant has already proposed a method of fixing a spiral spring which does not induce mechanical stress in such a spiral spring and does not move it from its rest position. This process

CH 714 775 B1 consists in sticking the last turn on the outside of a spiral spring in a piton by means of a drop of fluid adhesive which can be polymerized, for example by means of ultraviolet radiation. Thus, even if, when depositing the drop of glue, for example by means of a syringe-type glue distributor, the free end of the last turn of the spiral spring moves a little under the effect of the weight of the drop of glue, which induces unwanted mechanical stresses in the spiral spring, the glue is, before hardening, sufficiently fluid to allow the free end of the last turn of the spiral spring to spontaneously return to its rest position. The mechanical stresses induced in the spiral spring when depositing the drop of liquid adhesive therefore disappear on their own, so that the regularity of the running of the spiral spring is not affected by the bonding operation of this latest.

The above solution thus makes it possible to fix a spiral spring by the free end of its last turn on the outside in a piton by totally or at least for the most part eliminating the mechanical stresses which are usually induced in such a spiral spring during its mounting. The regularity of the spiral spring is thus greatly improved. In use, the Applicant has nevertheless realized that the pad of hardened glue formed when the drop of liquid glue is polymerized, which is used to fix the free end of the last turn outside the spring. hairspring sometimes tended to separate from the piton, which, of course, led to the immediate failure of the clockwork movement in which this hairspring spring was installed. Such a situation in which the block of glue in which the free end of the last turn is trapped outside the spiral spring detaches from the piton is in particular due to problems of surface condition of the piton which prevent the stud from glue to adhere perfectly to the peak.

SUMMARY OF THE INVENTION The aim of the present invention is to solve the problems mentioned above as well as others by providing a new type of peg whose geometry makes it possible to guarantee that the adhesive pad in which is trapped the free end of the last turn outside the spiral spring will not dissociate from the piton even if this adhesive pad no longer adheres to the piton.

To this end, the present invention relates to a stud for fixing, by means of a glue pad, a free end of a last turn outside a spiral spring for a movement of horology, this stud comprising a base which extends in a plane and a first arm and a second arm which extend from this plane, the arms being free at their end opposite to the base, the first and the second arms being separated from each other by a gap in which is housed the free end of the last turn outside the spiral spring which is trapped in the pad of hardened glue, at least one of the first and second arm being provided with a stop means arranged to prevent the pad of hardened glue in which is trapped the free end of the last turn outside the spiral spring from emerging from the gap in which it is housed when this pad of hard glue ie no longer adheres to the peak.

According to a particular embodiment of the invention, at least one of the first and second arms is pierced right through with a hole.

According to another particular embodiment of the invention, at least the first arm is free at its end opposite to the base, and it comprises a groove at a distance from its free end, this groove extending in a plane which forms an angle with the plane of the base.

According to yet another particular embodiment of the invention, the stop means protrudes into the gap provided for receiving the pad of hardened glue in which is trapped the free end of the last turn in the outside the spiral spring.

According to yet another particular embodiment of the invention, the stop means is at least one bead which is made of material with the corresponding arm of the peak.

Thanks to these characteristics, the present invention provides a stud used for fixing the free end of the last turn outside a spiral spring for a clockwork movement, this stud being provided with a means d stop intended to prevent the adhesive pad in which the free end of the last turn outside the spiral spring is trapped from coming out of the gap in which this pad is housed when the latter no longer adheres to the stud .

The present invention applies to all types of known spiral springs. This can in particular be metal hairsprings typically made of steel. It can also be spiral springs made of silicon.

The present invention is also not limited to one type of glue in particular. Indeed, the free end of the last turn outside the spiral spring can for example be glued in the interstice of the piton by means of the adhesive well known under its name “shellac” (adhesive known by the same name or under the name “shellac” in English terminology), or else be bonded using a liquid adhesive which can, for example, be polymerized by means of UV radiation. The advantage of shellac lies mainly in the fact that it adheres well and durably to the piton. On the other hand, to the knowledge of the plaintiff, the bonding of hairsprings on the pegs by means of shellac has never been able to be automated and its success remains entirely dependent on the dexterity of the operator responsible for this. surgery. Shellac is a resin and the operator takes a small chip from it and places it in the gap to receive the free end of the last turn outside the spiral spring. After placing this end of the spiral spring in the pit of the piton, the operator briefly heats the shellac chip which melts and traps the free end of the last turn outside the spiral spring. The operator then leaves the gum

CH 714 775 B1 lacquer to cool and, after visual inspection, decides whether to add an additional amount of shellac or whether it can be passed to the next spiral spring / piton assembly. We understand that such a succession of operations is difficult to automate. This is why it has been proposed to bond the spiral springs, in particular those made of silicon, by means of a liquid adhesive which can be polymerized using UV radiation or which is capable of hardening on contact with air. As already mentioned above, the fluidity of such a type of glue is such that after depositing a drop of this glue, the free end of the last turn outside the spiral spring can spontaneously return to its rest position from which it was removed when the adhesive was deposited. Above all, the quantity of liquid glue deposited can be controlled very precisely and entirely automated using a glue dispenser such as a syringe still known by its Anglo-Saxon name "dispenser". After the drop of liquid glue has been deposited, it is cured by sunshine using a UV lamp. It is clear that such a process is easily automated. On the other hand, the drawback of the photopolymerizable glue is that its adhesion to the piton is not very satisfactory and that the risks that the glue pad in which the free end of the last turn outside the spiral spring is trapped detaches from the peak are raised.

It is to address these problems that the present invention proposes to provide a timepiece with a stopper means to prevent the adhesive pad in which is trapped the free end of the last turn to the outside of the spiral spring to detach from this peg. The piton is typically in the form of a base which extends in a plane from which two arms separated from each other by a gap provided to receive the free end of the last turn outside extend. The stopping means can take various forms, among which there may be mentioned, without limitation, a hole which runs right through one at least of the two arms. Once the free end of the last turn outside the spiral spring is positioned in the pit of the piton, the drop of liquid glue is applied. By capillary action, it will in particular diffuse into the hole in which it will remain trapped and harden after exposure by means of UV radiation. Consequently, if, during its life, the glue pad comes to separate from the piton, it will however fail to free itself from the gap in which it is housed, so that this will not be felt on the operation of the watch movement.

The stopping means can also be provided in the form of an element, for example a bead, projecting into the interstice of the piton in which is housed the free end of the last turn outside the spiral spring. In this case too, if the adhesive pad in which the free end of the spiral spring is trapped disengages from the peg, this hardened adhesive pad cannot escape from the gap.

According to yet another particular embodiment of the invention, at least one of the first and second arms of the stud comprises a groove which extends in a plane which forms an angle with the plane of the base. This groove defines a hook which acts as a means of stopping the glue pad.

The invention also relates to a method of manufacturing a stud for fixing a free end of a last turn outside of a spiral spring for a clockwork movement, this stud comprising a base which extends in a plane and a first arm and a second arm which extend from this plane, the arms being free at their end opposite to the base, the first and the second arms being separated one of the other by a gap intended to accommodate the free end of the last turn outside the spiral spring which will be trapped in a pad of hardened glue, the gap being initially produced with a first width, the process comprising step which consists in widening the gap by stamping and in creating, by pushing back material, a stop means formed by at least one bead which projects into the gap provided for housing the pad of hardened glue da ns which will be trapped the free end of the last turn outside the spiral spring.

BRIEF DESCRIPTION OF THE FIGURES Other characteristics and advantages of the present invention will more clearly match the detailed description which follows of an exemplary embodiment of a piton according to the invention, this example being given purely by way of illustration and nonlimiting only in conjunction with the appended drawing in which:

fig. 1A and 1B are views respectively in elevation and in perspective of a first embodiment of the invention in which the first and second arms of the stud according to the invention are pierced with a hole right through;

fig. 1C is a view similar to that of FIG. 1B on which we see a silicon spiral spring whose free end of the last outside coil is fixed on the peg by means of a glue pad;

fig. 2A, 2B and 2C are views in elevation and in perspective of a second embodiment of the invention in which a groove machined in the first and second arms of the stud according to the invention delimits two hooks;

fig. 2D is a view similar to that of FIG. 2C on which we see a silicon spiral spring whose free end of the last outside coil is fixed on the peg by means of a glue pad;

CH 714 775 B1

fig. 3A is a perspective view of a third embodiment of the invention in which a bead formed on each of the internal lateral surfaces facing the first and second arms of the stud according to the invention protrudes into the gap; fig. 3B is a view similar to that of FIG. 3A, on which we see a silicon spiral spring, the free end of the last turn of which is outside, is fixed to the peg by means of a glue pad; fig. 4A and 4B schematically illustrate a first variant of the method of machining the beads on the internal lateral surfaces facing the first and second arms of the piton; fig. 5A to 5D schematically illustrate a second variant of the method of machining the beads on the internal lateral surfaces facing the first and second arms of the piton, and fig. 6A and 6B schematically illustrate the method of bonding the free end of the last turn to the outside of a spiral spring on the stud using a pad of glue.

Detailed description of an embodiment of the invention The present invention proceeds from the general inventive idea which consists in providing a stud intended for fixing a spiral spring with a clockwork movement of a stop means provided to prevent a free end of a last turn outside the spiral spring from decoupling from the stud and causing the immediate stop of the clockwork movement. More specifically, the piton comprises a base which extends in a plane from which extend a first and a second arm separated from each other by a gap. This gap is intended to receive the free end of the last turn outside the spiral spring which will be immobilized by means of a glue pad hardened by ultraviolet radiation. According to the invention, at least one of the two arms of the piton is provided with a stop means provided to prevent the adhesive pad, and therefore the free end of the turn outside the spiral spring, to escape from the gap in case the glue pad comes to separate from the stud. This stop means can be in various forms such as, without limitation, a hole, a bead or even a hook.

In the following detailed description of several particular embodiments of the invention, we will focus on the bonding of a silicon spiral spring by means of a liquid adhesive intended to be polymerized by means of a ultraviolet radiation. It will however be understood that the invention is not limited to this particular embodiment and that it applies in an identical manner to any type of spiral spring such as the metallic spiral springs produced for example by means of an alloy of steel.

Referred to as a whole by the reference numeral 1, a first particular form of execution of a stud 2 according to the invention is shown in FIGS. 1A and 1B annexed to this patent application. As can be seen by examining these two figs. 1A and 1B, the stud 2 comprises a base 4 which extends in a plane P on which stand a first arm 6 and a second arm 8 which are free at their end opposite to the base 4. In the example shown in the drawing, the first and second arms 6 and 8 extend perpendicular to the plane P of the base 4 and are separated from each other by a gap 10 substantially parallelepiped. Still on fig. 1A, 1B, it can be seen that the external surfaces 12 and 14 of the first and second arms 6 and 8, that is to say the surfaces of these two arms 6 and 8 which do not delimit the gap 10, tend to converge towards each other as these two arms 6 and 8 move away from the base 4, so that it is immediately understood that if the gap 10 was filled and the two arms 6 and 8 joined together, these two arms 6 and 8 would be inscribed in an outer frustoconical envelope. This geometry for piton 2 is preferred in particular for dimensions and the ease of adjustment of the racket (not shown) which belongs to the watch movement. However, this geometry is in no way imposed by the needs of the invention and other external shapes of the stud 2 can be envisaged without departing from the scope of the invention defined in the claims.

According to the invention, the stud 2 is provided with a stopping means provided to prevent an adhesive pad 16 in which is trapped a free end 18 of a last turn outside of a spring spiral 20 to escape from the gap 10 in the case where the adhesive pad 16 is detached from the stud 2. According to the first particular embodiment 1 of the invention, this stop means is in the form a hole 22 drilled right through in at least one of the first and second arms 6, 8. In the example illustrated in FIGS. 1 A, 1 B, a hole 22 is drilled in each of the two arms 6 and 8. The example of a spiral spring 20 in silicon more particularly visible in FIGS. 6A and 6B is conventionally constituted by a very thin spring wound in concentric turns and whose section is constant over substantially its entire length. This spiral spring 20 is fixed via a free end 24 of a first turn inside to a pendulum axis of the watch movement (not shown) for example by means of a ferrule 28, and via the free end 18 of its last turn outside at stud 2 according to the invention. To this end, the last turn outside the spiral spring 20, slightly thicker than the other turns over part of its length, can be provided at its free end 18 with a plate 30 made in one piece with the spiral spring 20. The presence of the plate 30 is dictated by considerations specific to the technique of manufacturing the spiral springs 20 in silicon only. It is important to understand that the presence

CH 714 775 B1 of this plate 30 is in no way made necessary by the needs of the present invention and that it is quite possible to fix a spiral spring devoid of such a plate on the stud 2 according to the invention.

In the example illustrated in Figs. 1A to 1C, a hole 22 is drilled right through in each of the two arms 6 and 8. Thus, when the liquid adhesive is deposited in the gap 10, it diffuses into the holes 22 by capillarity, holes 22 in which the liquid adhesive will remain trapped and harden after exposure by means of UV radiation or else in contact with air. An adhesive pad 16 is thus formed in which the free end 18 of the last turn outside the spiral spring 20 is trapped. Consequently, if, during its lifetime, the adhesive pad 16 comes to separate or come off from the piton 2, it will however not succeed in emerging from the interstice 10 in which it is housed and in decoupling from the piton 2 according to the invention, so that this will not affect the operation of the watch movement. In fact, the adhesive pad 16 will not be able to emerge from the gap 10 in particular in the region where the liquid adhesive has hardened in the holes 22.

In what follows, the elements identical to those described in connection with FIGS. 1A to 1C will be designated by the same reference numbers.

Designated as a whole by the general reference numeral 36, a second particular embodiment of a stud 2 according to the invention is shown in FIGS. 2A to 2C annexed to this patent application. According to this second embodiment 36, a groove 38 which extends in a plane which forms an angle with the plane P of the base 4 is machined in at least one of the first and second arms 6, 8. In the example illustrated in FIGS. 2A to 2C, the groove 38 is machined in the two arms 6 and 8 and extends in a plane perpendicular to the plane P of the base. Thus machined, the groove 38 delimits for each of the first and second arms 6 and 8 a hook 40 which, once the adhesive pad 16 has hardened for example by exposure by means of UV radiation or in contact with air, will retain the resulting adhesive pad 16 and prevent it from emerging from the gap 10 in the event that the adhesive pad 16 detaches from the peg 2. In fact, combined with the clearance formed by the groove 38, the hooks 40 form two bearing surfaces 42 on which the liquid adhesive will deposit by capillary action before hardening to form the adhesive pad 16 and which will prevent any possible removal of this adhesive pad 16.

[0033] FIG. 2D is a view similar to those of FIGS. 2A to 2C on which we see the silicon spiral spring 20 fixed on the stud 2 by the free end 18 of its last turn on the outside by means of an adhesive pad 16.

Referred to as a whole by the general reference numeral 44, a third particular embodiment of a stud 2 according to the invention is shown in FIG. 3A annexed to this patent application. According to this third particular embodiment 44 of the invention, the stop means protrudes into the gap 10 provided for receiving the pad of hardened adhesive 16 in which the free end 18 of the last turn is trapped. the outside of the spiral spring 20. By way of an illustrative and nonlimiting example only, the stop means is in the form of a bead 46 made from one piece with each of the internal lateral surfaces 48 which face the first and second arm 6 and 8. It will be understood that once the adhesive pad 16 in which the free end 18 of the last turn is trapped outside the hardened spiral spring 20, the beads 46 which project into the interstice 10 definitively prohibit the adhesive pad 16 from escaping from this interstice 10 in the event that the latter comes to come off from the stud 2.

[0035] FIG. 3B is a view similar to that of FIG. 3A on which we see the silicon spiral spring 20 fixed by the free end 18 of its last turn outside on the stud 2 by means of a glue pad 16.

One possible technique for producing the beads 46 is illustrated in FIGS. 4A and 4B. This technique consists of providing a peg 2 having a gap 10 whose initial width is d1, then introducing into this gap 10 a stamping tool 50 whose width d2 is greater than the width d1 and corresponds to the final width of the interstice 10 sought. By forcing the stamping tool 50 in the gap 10, the material is pushed back and a bead 46 is created on each of the internal lateral surfaces 48 of the first and second arms 6, 8. It will be noted that the beads 46 correspond to a preferred but non-limiting embodiment of the invention. Indeed, to obtain a stop means protruding into the gap 10, it can also be envisaged, for example, to drill right through one at least of the two arms 6, 8, then to introduce into the orifice thus obtained a pin which projects into the gap 10.

Another possible technique for creating an annular collar 52 is illustrated in FIGS. 5A to 5D. This technique consists of providing a piton 2 having a gap 10, then introducing into this gap 10 a drilling tool 54 whose end is conical. By advancing the drilling tool 54 in the gap 10 from the free end of the arms 6, 8 towards the base 4, a first hole 56 is created in the stud 2 (fig. 5B). Conversely, a second hole 58 is machined in the stud 2 from the base 4 towards the free end of the first and second arms 6, 8 (fig. 5A). The machining is carried out so that the second hole 58 partially opens into the first hole 56, locally retaining the annular flange 52 on the internal lateral surfaces 48 of the first and second arms 6 and 8 (fig. 5C). After having engaged the spiral spring 20 through the free end 18 of its last turn on the outside in the gap 10 and having deposited a drop of liquid glue, the latter is hardened so as to form a glue pad 16 (fig . 5D). The adhesive pad 16 thus formed is retained by the annular collar 52, so that even if this pad 16 detaches from the stud 2, it will be retained inside the gap 10 from which it cannot escape. .

It goes without saying that the present invention is not limited to the embodiment which has just been described and that various modifications and simple variants can be envisaged by those skilled in the art without departing from the scope of the invention Phone

CH 714 775 B1 as defined by the appended claims. In particular, in connection with FIGS. 6A and 6B, a diagrammatic illustration is given of the method for bonding the free end of the last turn to the outside of a spiral spring on a peg according to the invention. In fig. 6A, the free end 18 of the last turn outside the spiral spring 20 is disposed by its plate 30 in the gap 10 of the peg 2 and is bonded by means of a drop of liquid glue 32 capable of being polymerized by means of a source of ultraviolet radiation 34. This drop of liquid glue 32 is for example deposited by means of an automated dispensing device 60 such as a syringe still known by its Anglo-Saxon name "dispense". The exposure of the drop of liquid glue 32 to ultraviolet light allows its polymerization and its complete hardening. It will be noted that the example of liquid adhesive polymerizable by exposure to ultraviolet light is given by way of example only, and that other types of liquid adhesives such as an adhesive hardening in contact with air can be envisaged. .

Nomenclature [0039]

1.1 First particular form of execution

2. Piton

4. Sub-base

P. Plan

6. First arm

8. Second arm

10. Interstice

12.14. Outdoor surfaces

16. Glue pad

18. Free end outside

20. Spiral spring

22. Hole

24. Free end inside

28. Ferrule

30. Brochure

32. Glue drop

34. Ultraviolet radiation source

36. Second particular form of execution

38. Groove

40. Hooks

42. Support surfaces

44. Third particular form of execution

46. Beads

48. Internal side surfaces

50. Forging tool d1. Initial width d2. Final width

52. Annular collar

CH 714 775 B1

54. Drilling tool

56. First hole

Claims (5)

58. Second hole 60. Glue dispenser Claims 1. Piton for fixing, by means of a glue pad (16), a free end (18) of a last turn outside a spiral spring (20) for a clockwork movement , this peak (2) comprising a base (4) which extends in a plane (P) and a first arm (6) and a second arm (8) which extend from this plane (P), the arms (6, 8) being free at their end opposite to the base (4), the first and second arms (6, 8) being separated from each other by a gap (10) in which is housed the free end (18) of the last turn outside the spiral spring (20) which is trapped in the hardened adhesive pad (16), at least one of the first and second arms (6, 8) being provided with a stop means arranged to prevent the hardened adhesive pad (16) in which is trapped the free end (18) of the last turn outside the spiral spring (20) from coming off the gap (10) da ns which is housed this hardened adhesive pad (16) when this hardened adhesive pad (16) no longer adheres to the peg (2). 2. Piton according to claim 1, characterized in that at least one of the first and second arms (6, 8) is drilled right through with a hole (22). 3. Piton according to claim 1, characterized in that at least the first arm (6) comprises a groove (38) at a distance from its free end, this groove (38) extending in a plane which forms an angle with the plane (P) of the base (4) and which delimits for at least the first arm (6) a hook (40) forming a bearing surface (42) retaining the adhesive pad (16) hardened. 4. Piton according to claim 1, characterized in that the stop means protrudes into the gap (10) housing the adhesive pad (16) hardened in which is trapped the free end (18) of the last turn outside the spiral spring (20). 5. Piton according to claim 4, characterized in that the stop means is at least one bead (46) which is made of material with the arm (6, 8) corresponding to the piton (2).