Method for manufacturing watch assembly and watch assembly

Abstract

A watch assembly comprising a first watch part (10) assembled with a separate second watch part (20), the first watch part (10) comprising at least one functional part and a receiving opening (11) capable of constituting a connecting hole separate from the functional part, the walls dividing the receiving opening (11) forming a first connecting surface (12), the second watch part (20) comprising a second connecting surface (22) and being securely assembled to the first watch part by direct or indirect contact between the first and second connecting surfaces (12, 22) of the first and second watch parts (10, 20) respectively at the fixing surface, at least one of the first and second connecting surfaces (12, 22) or the third connecting surface of any intermediate third part (30) being made of silicon which is oxidized by heat treatment so that the first and second watch parts are fixed to each other by the growth of a layer of silicon oxide.

Description

[Technical field]

[0001] The present invention relates to a clock assembly of at least two clock parts. The present invention also relates to a clock movement and a clock comprising at least one such clock assembly. The present invention also relates to a method for manufacturing such a clock assembly. [Background technology]

[0002] In watches, ceramics are increasingly used, for example to form watch stems, because their inherent mechanical properties, in particular their hardness and insensitivity to magnetic fields, are highly advantageous for many watch components.

[0003] Conventional solutions used for assembling watch parts are solutions designed for metallic materials and are not always suitable or optimal for ceramics. In addition to this, silicon is also increasingly used in the manufacture of watch parts, and conventional solutions for assembling watch parts are likewise not always suitable or optimal for silicon due to the brittleness of silicon. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, one object of the present invention is to improve watch assembly and in particular to define a watch assembly solution that is particularly well suited to the use of ceramics.

[0005] More specifically, one objective of the present invention is to define a watch assembly solution that is reliable, durable and easy to implement. [Means for solving the problem]

[0006] For this reason, the invention relates to a watch assembly comprising a first watch part assembled with a separate second watch part, said first watch part comprising a receiving opening or a connecting hole, said wall delimiting said receiving opening or said connecting hole forming a first connecting surface and said second watch part comprising a second connecting surface, and being securely assembled to said first watch part by direct or indirect contact between the first and second connecting surfaces of said first and second watch parts respectively at a fixing surface, at least one of said first and second connecting surfaces or the third connecting surface of any intermediate third part being made of silicon which is oxidized by a heat treatment such that said first and second watch parts are fixed to each other by said growth of a layer of silicon oxide.

[0007] The first watch part may include at least one functional part and a receiving opening separate from the functional part.

[0008] According to a first embodiment, the contour of the receiving opening in the first watch part is closed, said receiving opening or connecting hole having a constant cross section over the entirety of its first connecting surface.

[0009] According to a second embodiment, the contour of the receiving opening opens onto the outer periphery of the first watch part, and the receiving opening or connecting hole may have a constant cross section over its entire first connecting surface, the height of which is comprised between a portion of the total thickness and the total thickness of the first watch part.

[0010] Furthermore, the second watch part may have a portion of variable cross-section, in particular increasing continuously from the interface with the second connecting surface, said portion of continuously increasing cross-section being positioned outside the receiving opening, or the connecting hole, immediately adjacent the end of the receiving opening.

[0011] The present invention also provides a method for manufacturing a watch assembly comprising a first watch part and a separate second watch part, comprising the steps of: Assembling the two watch parts in a minimum-gap intermediate configuration, such that the second watch part is positioned in a connecting hole or receiving opening of the first watch part, a first connecting surface of the first watch part being positioned opposite a second connecting surface of the second watch part, optionally via internal and external third connecting surfaces of a sleeve-type intermediate third part, at least one of the first and second connecting surfaces or the optional internal and external third connecting surfaces being made of silicone; a heat treatment of the timepiece assembly in an intermediate configuration in order to obtain the growth of a layer of silicon oxide on at least one connecting surface made of silicon until a predetermined level of fixation of the two timepiece parts to one another is obtained; The present invention relates to a method for manufacturing a watch assembly, comprising the steps of:

[0012] The invention is more particularly defined by the claims.

[0013] The objects, features and advantages of the present invention will be set forth in detail in the following description of specific embodiments, given by way of non-limiting example with reference to the accompanying drawings. [Brief description of the drawings]

[0014] [Figure 1a] FIG. 1a shows a first step of a watch assembly method according to one embodiment of the present invention. [Figure 1b] FIG. 1b shows a first step of a watch assembly method according to one embodiment of the present invention. [Figure 2a] FIG. 2a shows a second step of a watch assembly method according to an embodiment of the present invention. [Figure 2b] FIG. 2b shows a second step of a watch assembly method according to an embodiment of the present invention. [Diagram 3] FIG. 3 shows a third step of the watch assembling method according to one embodiment of the present invention. [Figure 4a] FIG. 4a shows an enlarged view of a third step of a watch assembly method according to an embodiment of the present invention. [Figure 4b]FIG. 4b shows an enlarged view of a third step of a watch assembly method according to an embodiment of the present invention. [Diagram 5] FIG. 5 shows a change in the tightening of the assembly in the fourth step of the watch assembling method according to one embodiment of the present invention. [Figure 6] FIG. 6 shows a part of a clock movement including a clock assembly according to a first embodiment of the invention. [Figure 7] FIG. 7 shows a part of a clock movement including a clock assembly according to a second embodiment of the invention. [Figure 8] FIG. 8 shows a first modified example of the third step of a timepiece assembling method according to one embodiment of the present invention. [Figure 9] FIG. 9 shows a second modified example of the third step of the timepiece assembling method according to one embodiment of the present invention. [Figure 10] FIG. 10 shows a third modified example of the third step of the timepiece assembling method according to one embodiment of the present invention. [Figure 11] FIG. 11 shows a fourth modified example of the third step of the timepiece assembling method according to one embodiment of the present invention. [Figure 12] FIG. 12 is an enlarged schematic diagram showing an assembly obtained by carrying out the third step and the fourth step of the timepiece assembling method according to the fourth modified embodiment of the present invention. [Figure 13] FIG. 13 is an enlarged schematic diagram showing an assembly obtained by carrying out the third step and the fourth step of the timepiece assembling method according to the fourth modified embodiment of the present invention. [Figure 14] FIG. 14 shows a fifth modified example of the third step of the timepiece assembling method according to one embodiment of the present invention. [Figure 15] FIG. 15 shows a balance wheel provided with a receiving opening for receiving a balance pin. [Figure 16] FIG. 16 shows a balance pin assembled to the balance wheel of FIG. 15 according to one embodiment of the present invention. [Figure 17] FIG. 17 shows a balance wheel provided with receiving openings for receiving impulse pins. [Figure 18]FIG. 18 shows an impulse pin assembled to the balance wheel of FIG. 17 according to one embodiment of the present invention. [Figure 19] FIG. 19 shows a jumper provided with a receiving opening for receiving a jumper spool. [Figure 20] FIG. 20 illustrates a jumper spool assembled with the jumper of FIG. 19 according to one embodiment of the present invention. [Figure 21] FIG. 21 shows a first part including a female portion forming an open receiving aperture according to another embodiment of the present invention. [Figure 22] FIG. 22 shows a second part including a male part assembled with the first part of FIG. 21 according to another embodiment of the present invention. [Figure 23] FIG. 23 illustrates a grooved connecting surface according to various embodiments of the present invention. [Figure 24] FIG. 24 illustrates a grooved connecting surface according to various embodiments of the present invention. [Diagram 25] FIG. 25 illustrates a grooved connecting surface according to various embodiments of the present invention. [Figure 26] FIG. 26 illustrates a grooved connecting surface according to various embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention advantageously relates to a method for manufacturing a watch assembly, the object of which is to reliably assemble at least two separate watch parts to form a firmly connected entity, here called a watch assembly. At least one of the watch parts of the watch assembly is advantageously mainly made of ceramic, i.e. completely or partially made of ceramic and / or advantageously comprises at least 50% by weight of ceramic. The ceramic is advantageously present on the connecting surface of said watch part which is mainly made of ceramic.

[0016] The ceramic is in particular zirconia, especially yttria-stabilized zirconia, in particular 3 mol % yttria-stabilized zirconia or 2 mol % yttria-stabilized zirconia, or monocrystalline or polycrystalline alumina or an alumina-zirconia compound. Alternatively, the ceramic may be a nitride, carbide and / or a boride of a refractory metal, alone or in combination with one another, or in combination with the oxides mentioned above, such as zirconia and alumina.

[0017] A method for manufacturing the watch assembly will now be described.

[0018] The first step in the method according to this embodiment is to procure two separate watch components which are assembled to form a firmly connected entity.

[0019] FIG. 1a illustrates a first watch part 10, which in this embodiment is a silicon gear. The first watch part 10 comprises in its center a receiving opening 11, also called "connecting hole", which corresponds to the hub of the gear. According to this embodiment, the receiving opening 11 (connecting hole) has a transverse cross section, i.e. a cross section perpendicular to its central axis, which is circular in shape. As a variant, said cross section may have other shapes, for example elliptical, oval, polygonal, etc., and may have at least one groove along its periphery, which may have a cross section of any type of shape. The at least one groove is provided to facilitate both the growth of the silicon oxide layer and the preliminary assembly of the two watch parts. The walls that delimit said receiving opening form a connection surface 12, which will be described below. The gear additionally comprises a periphery, which includes notches or teeth 13, which are intended to cooperate with other watch assemblies in the watch movement. Said periphery forms the functional part of the first watch part 10. Advantageously, said first watch part 10 may be manufactured in silicon, engraved from a standard silicon wafer by the traditional Deep Reactive In-Etching method (known by the abbreviation DRIE), in which several identical gears are formed simultaneously on the same silicon wafer.

[0020] FIG. 1b illustrates a second watch part 20, which is a ceramic arbour according to an exemplary embodiment, intended for assembly into the hub of the gear of FIG. 1a, separate from the first watch part, so as to allow the gear to be arranged with the ability to rotate in a watch movement. According to said embodiment, the second watch part 20 is intended to be mounted through a receiving opening 11 (connecting hole) of the first watch part 10. For this reason, in said embodiment, the second watch part 20 has a transverse cross section that is circular, i.e. a cross section perpendicular to its axis of rotation. As a variant, said cross section may have other shapes, for example elliptical, oval, polygonal, etc. The two ends 21 of the arbour are intended to be mounted in the watch movement so as to allow the arbour to rotate with minimal friction. The arbour may be manufactured from a bar in ceramic, by a laser turning method followed by friction finishing, which allows to obtain a precise shape and a controlled surface finish. The peripheral surface of the second watch part 20 comprises a second connecting surface 22 intended to be fixed to the first connecting surface 12 of the first watch part 10 in order to form a watch assembly of the two watch parts, as will be explained below. For this purpose, the second watch part 20 has a male connecting surface 22 intended to cooperate with a female connecting surface 22 belonging to the first watch part 10.

[0021] Figure 2a illustrates an intermediate phase of the second step of the assembly method, the phase in which a number of second watch parts 20 are brought close to a support 40 drilled with blind holes 41. Said support 40 is an intermediate element used temporarily in the manufacturing method. The support does not form part of the watch assembly. The support may be made of any material resistant to silicon oxidation temperatures. Advantageously, the support is of a material that has a similar coefficient of thermal expansion to that of the second watch parts 20.

[0022] Each second watch part 20 is inserted into a respective blind hole 41 of the support part 40, the diameter of which corresponds to the diameter of the second watch part 20, so that the second watch part 20 is held in a stable and precise manner by the support part 40 in the position shown in Figure 2b.

[0023] 3 illustrates a third step of the watch assembly method according to an embodiment of the present invention, in which the first watch part 10 is assembled onto the respective second watch part 20. For this purpose, the receiving opening 11 (connecting hole) of the first watch part 10 is placed opposite the upper end 21 of the second watch part 20, and then the first watch part 10 slides downwards along the second watch part 20 until it rests on the upper surface 42 of the support 40.

[0024] Fig. 4a shows in an enlarged view the configuration obtained at the end of the third step, forming an intermediate configuration of the assembly of the two watch parts. The two watch parts 10, 20 are positioned in their final relative position with respect to each other, but are not yet fixed to each other. In particular, the respective connecting surfaces 12, 22 face each other, but are separated by a small distance d, which represents the gap between the two parts, as shown in Fig. 4b. At this stage, the two watch parts do not come into contact with each other. The gap allows a relatively easy positioning of the two watch parts while guaranteeing a minimum mobility between them in the unfixed temporarily assembled position. Advantageously, the distance d is less than or equal to 4 μm, or less than or equal to 2 μm. Also advantageously, the distance d is greater than or equal to 1 μm, or greater than or equal to 1.5 μm. For this reason, the depth of the blind hole 41 in the support 40 is selected so that, when the first watch part 10 is positioned, the second connection surface 22 of the second watch part is located immediately above the upper surface 42 of the support so that it can be located opposite the first connection surface 12 of the first watch part 10.

[0025] It is noted that the same support 40, as illustrated in Figures 2 and 3, advantageously allows the simultaneous production of several watch assemblies. This is particularly advantageous when the first watch parts 10 are produced by micromachining from a wafer, in particular a silicon wafer, which are still fixed to the wafer, for example by means of tethers, and assemblies can be produced simultaneously for all or part of the parts connected to the wafer. Of course, the invention is not limited to such an embodiment, but also covers an embodiment in which a single watch assembly is produced.

[0026] The watch assembly method then carries out a fourth step of fixing the two watch parts to each other. For this, the assembly obtained at the end of the third step is subjected to a heat treatment so as to produce the growth of a layer of silicon oxide on the surface of the first watch part 10 made of silicon. For this, the assembly is advantageously placed in an oxidation furnace and heated to a temperature of the order of 1100° C., or more generally to any temperature sufficient to cause oxidation of the silicon. For this, advantageously, the temperature in question is between 800 and 1200° C., preferably in an oxidizing atmosphere (for example water vapor). In addition, the treatment time is selected so as to achieve a sufficient thickness of oxidation to sufficiently fix the two watch parts to each other.

[0027] In particular, when silicon oxidizes, a layer of silicon oxide is formed on the surface of the first watch part, including the connection surface that completely or partially covers the second watch part, which increases the overall volume. Thus, by continuing the operation for a sufficient time, the distance d separating the two respective connection surfaces of the two watch parts is filled with silicon oxide until a sufficient level of clamping is obtained between the two watch parts in direct contact between the respective connection surfaces. This phenomenon is illustrated in FIG. 5, where a first curve 51 shows the change in diameter of the receiving opening 11, in this case a connection hole of circular cross section, with respect to time during the oxidation operation. It can be seen that the diameter is significantly reduced. According to the illustrated embodiment, the diameter is reduced by 2 μm in 10 hours of treatment so that at the connection surface 22 it is equal to the diameter of the second watch part 20, a diameter that is illustrated by the second curve 52 and remains constant.

[0028] The change in thickness of the silicon oxide layer as a function of time follows the following principle.

[0029]

number

[0030] where t is the heat treatment time, e ox represents the thickness of the oxide layer, and A, B, and C are constants. Thus, from FIG. 5 it can be seen that a treatment lasting 40 hours reduces the diameter of the receiving opening 11 by 4 μm.

[0031] It is noted that the ceramic is capable of withstanding the silicon oxidation temperatures and is not affected by the heat treatment carried out, either in terms of its dimensions or its performance. In addition, the support 40 is likewise made of a material capable of withstanding the heat treatment so as to provide constant support for the entity during said heat treatment time.

[0032] Thus, the growth of a layer of silicon oxide on the connecting surfaces 12, which is continued until a sufficiently rigid connection is obtained, compatible with the stresses to which the watch assembly is exposed inside the watch movement, allows a direct fastening of the two connecting surfaces 12, 22 respectively, thus ensuring that the two watch parts remain permanently joined during operation of the watch assembly. It is noted that in this embodiment, the two connecting surfaces contact each other at a fixing surface, which in this embodiment is cylindrical in shape.

[0033] The shape of the parts is advantageously selected so as to allow assembly with minimal gaps in any case, while at the same time allowing sufficient gaps before the heat treatment to achieve sufficient mutual fixation by the heat treatment in an acceptable time. For this purpose, the connecting surfaces made of silicon oxide of the watch assembly after the heat treatment are advantageously selected to include a layer of silicon oxide with an average thickness of 1 μm or more, or 1.5 μm or more, and or 4 μm or less. In a variant, the shape of the parts is selected so that there is no contact between the first and second parts before the oxidative heat treatment, but that sufficient mutual fixation is achieved by the oxidative heat treatment in an acceptable time. In this case, the use of a support 40 is advantageous, as illustrated in figures 2 and 3.

[0034] It is worth noting that the walls delimiting the receiving opening 11 (connecting hole) of the first watch part 10 are connected to the surrounding functional part of said first watch part 10 by a connection, which in the described embodiment is rigid. More specifically, according to the presented example, the gear wheel hub is connected to the functional periphery by four rigid spokes. In other words, the walls of the receiving opening 11 are immovable relative to said functional part. The connection between the receiving opening and the functional part qualifies as a rigid connection, and more generally, such a watch part qualifies as a rigid type watch part. Of course, said rigid connection may be formed by any number of rigid spokes rather than the above mentioned four spokes, or by other connection structures not necessarily in the form of spokes.

[0035] Such a rigid connection offers significant advantages for the implementation of the watch assembly method of the invention, in particular during the final phase of the clamping of the two connection surfaces to one another, via the growth of a layer of silicon oxide. In particular, during said growth, forces are exerted on the two contacting connection surfaces. If the walls of the receiving opening (connection hole) are mounted with the ability to move relative to the remainder of the first watch part, in particular relative to the functional part, the forces exerted during the growth of the oxide may be absorbed by said movement, which may displace said walls of the receiving opening (of the connection hole), thus compromising the desired clamping of the connection surfaces. For this reason, rigid type watch parts within the meaning of the above definition are particularly well suited for the watch assembly according to the invention.

[0036] Figure 6 shows, by way of example, a part of a clock movement including a number of clock assemblies of the rigid type within the abovementioned meaning, more specifically including an escape wheel 2 pivoting about an axis A2 and a locking part 3 including, inter alia, a first locking gear 3a pivoting about a third axis A3a and a second locking gear 3b pivoting about a fourth axis A3b, these three elements being arranged in the same plane P and made of silicon, forming a regulating device 1 assembled with respective arbors made of ceramic using the clock assembly method according to the invention.

[0037] Other parts of clockwork mechanisms may benefit from the timepiece assembly according to the invention, for example: 15 and 16, a balance wheel 60 with a balance pin, of the kind encountered in a Swiss lever escapement. In this embodiment, the balance wheel 60, mainly made of silicon, has a receiving opening 62 which receives the balance pin 65. The contour of the receiving opening is closed and its shape complements that of the balance pin 65. The balance pin 65, preferably made of monocrystalline or polycrystalline alumina, is introduced with a very small amount of clearance into the balance wheel 60 perpendicular to its first face, until the fastening end of the balance pin 65 is flush with a second face of the balance wheel 60 parallel to the first face. Now that the two watch parts are positioned relative to each other, they are then assembled using the watch assembly method according to the invention. 17 and 18, a balance wheel 70 with an impulse pin 75, as encountered in types of escapements other than the Swiss lever escapement. In this embodiment, the balance wheel 70, made mainly of silicon with two parallel faces that delimit its height, has a receiving opening 72 for receiving the impulse pin 75. The receiving opening 72 has an open profile and opens into the periphery of the balance wheel 70. The impulse pin 75, preferably made of monocrystalline or polycrystalline alumina, fits in the balance wheel 70, parallel to the face of the balance wheel 70, with a very small amount of clearance. Once the protruding length of the impulse pin 75 has been adjusted to suit, the two watch parts are assembled using the assembly method of the invention. 19 and 20, a shape with an open contour receiving opening 82, like the opening 72 described above, is suitable for the assembly of a jumper spool 85 with a jumper 80, as for example used in a date mechanism.

[0038] Figures 21 and 22 illustrate another solution of assembly between a first part including a female part and a second part including a male part, which provides a seat for the male part protruding from the periphery of the female part. In that embodiment, the assembly involves a receiving opening 92 in the first watch part 90, which is open in profile and does not penetrate through the entire thickness of the first watch part 90. The depth of the receiving opening 92 is limited to a part, which may be 40% of the total thickness of the first watch part 90, to provide a seat 93 for the second watch part 95. In that configuration, the receiving opening is a blind hole and is sealed within the thickness of the first part, so that the second watch part 95 does not pass through the first watch part 90.

[0039] Very surprisingly, the applicant's research has demonstrated that the mechanical strength of the assembly is increased when the connection surface 12, intended to guide the second watch part, is disrupted by inserting at least one groove 110, as shown in figures 17, 18, 19, 20, 23, 24, 25 and 26. The at least one groove 110 is provided for various purposes, such as to simplify the preassembly of the watch parts by reducing the contact area, as well as to simplify the supply of oxygen to the connection surface 12 during the oxidation heat treatment, and, especially in the case of open-contoured receiving openings, to allow the prepositioning of the watch parts to be maintained even after oxidation, by preventing any movement of the male part that could be caused by the growth of a silicon oxide layer. The at least one groove 110 may have any kind of shape, including one that results in a succession of convex projections in the connection opening, as shown in figure 25. The at least one groove 110 may also be formed on the connection surface 22, as shown in figure 26.

[0040] As mentioned above, the cross-section of the receiving opening may be open or sealed, may be a blind hole or a through hole, may be circular or U-shaped, or may have other shapes, such as, for example, elliptical, oval, polygonal, etc.

[0041] As mentioned above, the present invention is particularly well suited for the manufacture of a watch assembly including a ceramic arbour. In addition, the present invention is particularly well suited for assembling said ceramic arbour with a first watch part made of silicon, in particular a silicon gear. In particular, silicon is increasingly being used for the manufacture of watch parts due to its highly advantageous properties. However, silicon has the disadvantage of being weak, in particular brittle, which makes it difficult to assemble with other parts. For this reason, the present invention is particularly advantageous for the formation of a watch assembly between a first watch part made of silicon and a second watch part made of ceramic.

[0042] Of course, in variants of the embodiment, the second watch part, and in particular the stem, can be made of a material other than ceramic, for example of another very hard material that can withstand the abovementioned oxidation temperatures, so that the above-mentioned embodiment, although particularly well suited to ceramics, can also be used in variants with watch parts made of materials other than ceramics.

[0043] For example, the second component may be made of a metal, particularly a metal alloy, capable of withstanding oxidation temperatures, including, but not limited to, Ti, Zr, Nb, Mo, Ta, W, and their respective alloys.

[0044] According to another embodiment, the first and second parts may be made of silicon Si. Such a configuration offers the advantage of reducing the oxidation time (with a simultaneous reduction in the size of the receiving opening of the first part and an increase in the size of the body of the second part) and / or making it possible to work with a larger initial gap.

[0045] Moreover, as mentioned above, the invention is particularly well suited for the creation of a watch assembly of two watch parts of the rigid type. However, it is also advantageous to use watch parts of the flexible type, where the expression "flexible type" is the opposite of the expression "rigid type". For this reason, a second embodiment of the invention relies on a watch assembly including a watch part including at least one flexible type, in particular elastically movable part. In particular, the first watch part may have a receiving opening (connecting hole) wall connected by an elastically movable connection to the functional part. Such a solution according to the second embodiment is less advantageous for the creation of such an assembly, i.e. the function of fixing the two watch parts to each other, but it offers the additional advantage of simplifying the temporary assembly of the configuration of FIG. 3, in which the two watch parts are temporarily assembled. In particular, due to the slight elastic mobility of one or more walls of the receiving opening (of the connecting hole) relative to the functional part of the first watch part, it is possible to move said walls during the temporary assembly of the two watch parts, thus reducing the gap between the respective connecting surfaces and making it possible to reduce the heat treatment time necessary to achieve the fixing to each other.

[0046] For this reason, such an embodiment based on at least one elastic type watch part represents a compromise: its (very small degree of) flexibility is chosen so as to allow a temporary positioning of the two watch parts, while limiting possible movements of the connecting surfaces in order to fully achieve their fixation to one another through the growth of the silicon oxide layer.

[0047] For this reason, Fig. 7 illustrates an embodiment variant of the governor of Fig. 6, including the same watch parts, the same reference numbers being maintained for ease of understanding, but in which the shape of the gears has been modified to introduce flexibility through elastic connections connecting the walls of the connection holes of the gears to their respective surrounding features, the connection holes in which the ceramic arbors are fixed by the watch assembly according to the invention. More specifically, as a preference, each of the gears includes a central receiving opening (connection hole) bounded by elastic spokes, the dimensions of which are defined so as to provide an appropriate holding torque to hold each of the gears on its respective arbors.

[0048] Of course, the invention is not limited to the above-described embodiments.

[0049] Thus, according to a first variant of the first or second embodiment, the second watch part 20 comprises a bearing surface 23. In the case of a vertex, said bearing surface 23 may be formed by a large diameter portion of the vertex. Figure 8 illustrates a third step of the manufacturing method for a watch assembly according to this variant embodiment. Comparing this embodiment with Figure 3 corresponding to the first embodiment described above, it becomes clear that the main difference arises from the fact that the first watch part does not rest on the surface 42 of the support 40, but on the bearing surface 23 of the second watch part. The support 40 continues to hold at least one second watch part, but the depth of its blind hole 41 is reduced, since the connection surface of the two respective watch parts is spaced above the upper surface 42 of the support 40. Of course, as a variant, any other shape of the second watch part may be implemented, forming the surface for receiving the first watch part and acting as a bearing surface. The presence of such a bearing surface may facilitate the assembly operations, but is not advantageous for the manufacture of the part, since it requires additional machining operations and a larger volume. It is also noted that the first watch part maintains the same shape as in the embodiment described above. The connection surface of the first watch part is kept as simple as possible, i.e. cylindrical, for example, by preference no countersinks are added to the surface which rests on the bearing surface 23.

[0050] FIG. 9 illustrates a second embodiment variant of the first or second embodiment, in which the temporary assembly of the third step of the watch assembly method is carried out directly on a silicon wafer 5, without a support, for example including at least one rough mold of a first watch part 10, which has not been completely detached from the wafer 5. In this second embodiment variant, the second watch part or parts also have a bearing surface 23, which rests on the upper surface 6 of the wafer 5, the wafer 5 also playing the role of a support in the configuration. It is noted that during the implementation of this second embodiment variant, the assembly resulting from the third step of the method and formed in the configuration shown in FIG. 9 is oxidized in a fourth step of the method. For this reason, the wafer 5 is oxidized in its entirety, and the rough molds of the first watch parts 10 intended to be detached are oxidized before the subsequent step of detaching each of the first watch parts 10 already assembled with the respective second watch parts 20. The oxidation of the entire wafer is not limited to this embodiment and may be carried out in any configuration, in particular in the configuration shown in FIG. 3 and / or 4. As in the above variant, the first watch part maintains the same shape as in the above-mentioned embodiment. The connection surface of the first watch part is kept as simple as possible, i.e. cylindrical. For example, by preference, no countersinks are added to the surface that rests on the bearing surface 23. It is noted that on the bearing surface 23 that forms the contact surface between the two watch parts, there is a growth of silicon oxide, but there is no fixing function at said contact surface between them. Thus, the surface where the two parts are fixed to each other is still a cylindrical surface, the same as in the variant described above.

[0051] Fig. 10 illustrates a third embodiment variant, which is also compatible with the first and second embodiments of the invention and their various variants. This third embodiment variant differs from all the above variants in that it employs an intermediate third part made of silicon, separate from the two watch parts to be assembled, the purpose of which is to join the watch assembly of the two watch parts to be assembled. This intermediate third part comprises a third contact area, which includes an internal third connection surface, which is intended to be in contact with the second connection surface of the second watch part 20 on the one hand, and an external third connection surface, which is intended to be in contact with the first connection surface of the first watch part 10 on the other hand. During the oxidation fourth step of the assembly method, the third connection area of ​​the intermediate third part oxidizes, leading to the growth of two silicon oxide layers, internally and externally, which contact the first connection surface of the first watch part and the second connection surface of the second watch part, respectively, until the three parts are fixed to each other as desired. In this third embodiment variant, the two connection surfaces 12, 22 of the two watch parts 10, 20 are in indirect contact, connected by a material continuation by the connection area of ​​the intermediate third part, respectively, whereas in the above-mentioned embodiment, they were in direct contact. In the illustrated example, the intermediate third part 30 takes the form of a sleeve, which is located on the one hand at and around the connection surface of the second watch part, and on the other hand in the receiving opening (connection hole) of the first watch part, opposite the first connection surface. The intermediate third part is assembled in an intermediate assembly configuration with a gap with each of the two watch parts to be assembled, which has the same dimensions as the gap described above between the two watch parts. In this embodiment variant, the mutual fixing surfaces of the two watch parts are present on each of the outer and inner faces, and are doubled. The two fixing surfaces are cylindrical in this case, but may also have an open contour and may also take other shapes, for example elliptical, oval, polygonal, etc., and / or may be grooved. It is noted that on the bearing surface 23, which forms the surface of contact between the two watch parts, there is a growth of silicon oxide, but there is no locking function at said surface, so that the locking surface of the two parts still remains cylindrical, as in the variant described above.

[0052] This third embodiment variant is suitable, for example, when neither of the two watch parts is made of silicon. Thus, for example, both may be entirely or mainly made of ceramic. As a variant, one of the parts is mainly made of ceramic and the other is made of another material. According to another embodiment, it is also suitable even if the respective connection surfaces of the two watch parts to be assembled do not have directly compatible dimensions, for example, when the receiving opening (connection hole) has a diameter that is too large compared to the second watch part to achieve a direct assembly between the two watch parts.

[0053] 11 to 14 respectively illustrate a fourth and a fifth embodiment in which the second watch part 20 has a variable transverse or radial cross section 25, i.e. a cross section 25 whose surface area is preferably continuously variable, in addition to being located in the immediate vicinity of the connecting surface 22, as will be explained below.

[0054] Figures 11 to 13 illustrate a fourth embodiment, which can be compared to the first embodiment variant of figure 8, in which the bearing surface 23 is replaced by a variable radial cross section 25, which changes continuously between the boundary of the second connecting surface 22 and the enlarged cross section. As illustrated in figures 12 and 13, said variable radial cross section 25 takes the form of a portion of a changing radial cross section, which develops continuously from a minimum radial cross section Se1 at the boundary with the second connecting surface 22 to a maximum radial cross section Se2. In said embodiment, the second watch part comprises as a whole a first cylindrical section of cross section Se1 and a second cylindrical section of enlarged cross section Se2, the two cylindrical sections being connected to each other by a variable radial cross section 25, which is interposed between them. Preferentially, said variation of cross section is linear. Alternatively, the variation may take any other shape. The second connecting surface 22 is located on the first cylindrical section, in the immediate vicinity of the variable radial cross section 25.

[0055] The first watch part 10 remains unchanged and comprises a receiving opening 11 (connecting hole), which according to an embodiment has a constant cross section.

[0056] FIG. 12 particularly illustrates the advantage of this configuration when implementing the third step of the invention. During the temporary assembly of the first watch part 10 with the second watch part 20, the receptacle 11 (connecting hole 11) slides with a reduced clearance onto the second watch part 20 until its entry end abuts the variable radial cross-section portion 25 of the second watch part 20, in order to achieve the unfixed intermediate assembly configuration illustrated in FIG. 12, where the clearance is within the range described above with reference to FIG. 4b. The contact obtained between the two watch parts is therefore of the linear contact type. It is noted that the variation of the cross-section of the variable radial cross-section portion 25 is such that the maximum cross-section Se2 is greater than the cross-section of the receiving opening 11. Conversely, the minimum cross-section Se1 is such that the receiving opening 11 can cooperate with the minimum cross-section of the second watch part 20 with a minimum clearance, where the clearance is the clearance described in the previous variant between the two connecting surfaces 12, 22.

[0057] In said intermediate assembly configuration, the entity is advantageously positioned on a support 40, as in the first variant illustrated in Fig. 8, which holds, inter alia, the second watch part or parts 20 in a vertical orientation in order to maintain, under the effect of gravity, the line of contact between the two watch parts in a substantially horizontal plane, perpendicular to the axis of the second watch part 20. According to such a fourth embodiment variant, the linear contact between the two parts is of circular shape, but may take any kind of shape, or an aperture contour, and / or may have grooves forming a discontinuous linear contact.

[0058] FIG. 13 illustrates the assembly obtained after carrying out a fourth step, which involves fixing the two watch parts together by a silicon oxidation heat treatment as described above. At the end of said fourth step, a uniform thickness e oxA layer of silicon oxide 15 is formed on the surface of the product made of silicon, in this case the first watch part 10. As mentioned above, the formation of said layer of silicon oxide is accompanied by an increase in volume that moves the first connecting surface 12 of the first watch part 10 until it comes into contact with the second connecting surface 22 of the second watch part 20 in order to fix the two watch parts together. It is noted that the uniformity of the thickness of the layer of silicon oxide 15 is also the reason why the corners of the first watch part 10 made of silicon are rounded, as illustrated by circular arcs in Fig. 13.

[0059] According to this embodiment variant, as the layer of silicon oxide gradually grows on the surface of the first watch part 10, the cross section of the receiving opening 11 (connecting hole) decreases, which causes the first watch part 10 to move relative to the second watch part 20. In particular, the area of ​​linear contact gradually rises as the cross section decreases (moving more generally along the axis of the second watch part in FIG. 12). The variable radial cross section portion 25 of the second watch part 20 thus forms a guiding ramp that guides the relative movement of the first watch part during the fourth step of the method, the oxidation step. The phenomenon continues until the first watch part 10, more particularly the linear contact with the second watch part 20, reaches the boundary between the variable radial cross section portion 25 and the second connecting surface 22. At this point, the growth of the layer of silicon oxide no longer causes the first watch part 10 to move, and ends the fixation of the two respective connecting surfaces 12, 22 to each other according to the final configuration of FIG. 13.

[0060] It is noted that the relative movement of the two watch parts 10, 20 in this fourth embodiment variant facilitates movement in two directions, not only in the axial direction mentioned above, but also in the radial direction, which allows relative re-centering of the two watch parts 10, 20 in the event of any offset in the intermediate configuration.

[0061] Finally, the shape of the second watch part 20 advantageously forms, on the one hand, a means of prepositioning of the first watch part 10, and on the other hand makes it possible to prevent sudden variations in the cross section of the second watch part 10, which would be detrimental in terms of mechanical strength, especially when the material used has low impact resistance and / or when the cross sections involved are small. It is also clear that the embodiment greatly facilitates obtaining a uniform silicon oxide layer 15 and an accurate relative positioning of the two watch parts after the heat treatment. The above-mentioned advantages are particularly noted for configurations that utilize a bearing surface on the second watch part, and more particularly for configurations that combine said bearing surface with a counterbore arranged in the receiving opening 11 of the first watch part 10, as for example shown in figures 8 and 9. The embodiment variant thus optimizes the reinforcement of the robustness of the oxidation shrink fitting method. The advantage of this embodiment variant with linear contact before heat treatment arises, inter alia, from the uniformity of the silicon oxide layer obtained, as mentioned above, which can be explained by the fact that the entire surface of the silicon watch part remains exposed, except for the linear contact, as well as to the oxidizing atmosphere prevailing during heat treatment.

[0062] According to one embodiment, the variable radial cross section portion 25 of the second watch part 20 may be manufactured in a turning operation, as mentioned above, especially when the second watch part is entirely or partly made of ceramic. In addition, said variable deformation direction cross section portion 25 may exhibit a linear variation, in this case a truncated cone shape. According to one embodiment, the variable radial cross section portion may have an opening angle "α" that represents a compromise between a small value, which promotes the mechanical strength of the watch part through the absence of abrupt variations in the radial cross section, i.e. the absence of stress concentrations in said area, in the linear truncated portion, and a larger value, which promotes the relative positioning of the two watch parts due to a low sensitivity to manufacturing tolerances, since the dimensional variations of the receiving opening 11 of the first watch part 10 or the variable radial cross section portion 25 of the second watch part 20 are offset by a small axial movement. Advantageously, the angle "α" is between 10 and 80 degrees, or between 30 and 60 degrees. For example, a choice of an angle "α" of 45 degrees or close to 45 degrees represents a good compromise.

[0063] Figure 14 illustrates a fifth embodiment variant, comparable to the second variant of figure 9, in which, like the fourth variant described above, the bearing surface is replaced by a variable radial cross-section portion 25. The work obtained during the oxidation step is similar to that described in the previous variant, and the advantages obtained are similar.

[0064] The present invention is not limited to the above-described embodiments, for example, the specific embodiment variants described above may be combined with each other to form other embodiment variants.

[0065] The invention also relates to a watch assembly resulting from the above-mentioned watch assembly method, comprising a first watch part assembled with a separate second watch part, the first watch part comprising at least a functional part and a receiving opening (connecting hole) separate from said functional part, the wall delimiting said receiving opening forming a first connecting surface and the second watch part comprising a second connecting surface, said watch part being securely fixed to the first watch part via direct or indirect contact between the first and second connecting surfaces of the first and second watch parts respectively.

[0066] Indirect contact between the two connecting surfaces is the term used herein for a configuration in which one or more layers of other material, separate from the two watch parts, are interposed between the two connecting surfaces, forming a continuity of material between the two connecting surfaces to enable the two watch parts to be fixed to one another.

[0067] In each case, either the first and second connecting surfaces or one of the inner and / or outer third connecting surfaces of any intermediate third part is made of silicon which is oxidized by heat treatment, so that the first and second watch parts are fixed to one another by the growth of a layer of silicon oxide.

[0068] It is therefore clear that the silicon oxide surface, through its growth, is sufficient to form a sufficient interference fit at the connection surface to fasten the two watch parts to one another by fastening with the corresponding connection surface. As mentioned above, the two watch parts are first positioned in the intermediate assembly configuration before the growth of the silicon layer, which is oxidized by heat treatment, in order to fasten the two watch parts in their final position corresponding to the intermediate assembly configuration. Such a watch assembly is therefore different from a watch assembly that may include parts made of silicon oxide, but which are connected to each other by conventional methods such as gluing or hammering, and not through the intermediation of silicon oxide. In the latter case, the silicon oxide will inevitably break in a detectable manner due to the presence of defects in the mechanical bond that is performed following the oxidation in the connection between the two parts, which, in addition to deformation, leads to the risk of peeling or cracking of the silicon oxide layer. On the contrary, by implementing the present invention, the silicon oxide layer remains defect-free at the watch part connection surfaces, more specifically at the surfaces that are fastened to each other via its surfaces. Furthermore, although the implementation of the present invention does not require the addition of any other means of fastening the two parts to each other, as in prior solutions, the present invention is not incompatible with the optional use of a separate, additional, second fastening means.

[0069] The above mentioned watch parts may be of the gear type, such as an escape wheel, or of the pinion type, such as an escapement pinion, or may be a balance spring, on the one hand, and a stem, on the other hand. Of course, the invention applies more generally to any first watch part of the "female" type that is assembled with any second watch part of the "male" type.

[0070] Moreover, as mentioned above, the invention is particularly well suited for at least one of the watch parts being made of ceramic or being mainly made of ceramic. The watch part may be a first and / or a second watch part. The watch part may be a "female" watch part and / or a "male" second watch part.

[0071] It is noted that at least one connection surface made of silicon oxidized by heat treatment, or more generally a connection surface of a female watch part, may surround a second, male watch part, completely or over at least 70% of its circumference, or over at least 40% of its circumference, considering at least one cross section in a transverse plane, i.e. in a plane substantially perpendicular to the axis or to the direction of the longitudinal extent.

[0072] Furthermore, the mechanical connection between the two parts is achieved over the entire height of the connection surface delimited by the receiving opening of the first watch part. For this reason, the growth of silicon oxide is achieved between the two connection surfaces, i.e. in a lateral direction as defined above, which would also be radial if the second watch part were to take its true shape. The resulting fixing surface, which fixes the two watch parts to each other, extends perpendicularly to said lateral or radial silicon oxide growth on the surface of the receiving opening of the female part.

[0073] Continuing the consideration of the transverse (radial) cross-section of the connection between two watch parts, the receiving opening (connecting hole) of the first watch part may have a circular first cross-section and the connecting surface of the second watch part may have a circular second cross-section, the diameter of the circular first cross-section being strictly greater than or equal to the diameter of the circular second cross-section before oxidation by heat treatment. As a variant, one of the first or second connecting surfaces may have a circular first cross-section and the other may have a non-circular, in particular oval or elliptical or polygonal, cross-section that allows the assembly of the two watch parts to center itself when both are positioned in the intermediate assembly configuration. As a further variant, the two first and second cross-sections of the first and second connecting surfaces, respectively, may have the same non-circular, in particular oval or elliptical or polygonal, cross-section. As a further variant, the first and / or second connecting surface may have a cross-section of discontinuous shape and / or that may or may not be constant over the entirety of the receiving opening. From this it becomes evident that the fixed surface or surfaces of the two watch parts are preferably inscribed in a cylindrical or oval or elliptical or polygonal or cylindrical shape, in the case of one fixed surface being discontinuous or oval or elliptical or polygonal.

[0074] The receiving opening 11 (connecting hole) of the first watch part 10 may be a through opening or a blind opening.

[0075] The connection surface 12 of the first watch part 10, which is complementary to the connection surface 22 of the second watch part 20, may advantageously be disrupted by the insertion of grooves 110, in particular to facilitate the supply of oxygen to the connection surface 12 during the oxidative heat treatment.

[0076] As a variant, the creation of an alternating sequence of guide portions and grooves may be applied to the connecting surface 22 of the second watch part 20, as shown in FIG.

[0077] The connecting surface of one watch part, either the first watch part or the second watch part, which is not made of silicon oxide but is, for example, made of ceramic, may be configured to have increased roughness or may include knurling or grooves or keyways and / or may be flat.

[0078] The connection surfaces of the watch parts, which are mainly made of ceramic, may be subjected to a treatment that makes them chemically compatible with silicon oxide.

[0079] The second watch part may include a supporting bearing surface.

[0080] As a variant, the second part may have a section of variable cross-section, in particular a section of continuously increasing cross-section from its interface with the second connecting surface, said section of continuously increasing cross-section being positioned outside the receiving opening of the first watch part, immediately adjacent to the end of said receiving opening. Said section of variable cross-section has been explained in more detail in the embodiment variant with reference to figures 11 to 14.

[0081] The silicon oxide connecting surface may have an average thickness of 1 μm or more, or 1.5 μm or more. The connecting surface may have an average thickness of 4 μm or less.

[0082] The present invention also relates to a clock movement comprising one or more of the above-mentioned clock assemblies.

[0083] The invention also relates to a timepiece including at least one of the above-mentioned timepiece assemblies or including said timepiece movement.

Claims

1. A first watch part (10), and A second watch part (20) separate from the first watch part (10), the separate second watch part (20) assembled with the first watch part (10), and including, The first watch part (10) includes a receiving opening (11) or a connection hole, and the wall separating the receiving opening (11) or the connection hole forms a first connection surface (12), The second watch part (20) includes a second connection surface (22), and is a watch assembly that is securely assembled to the first watch part by direct or indirect contact between the respective first and second connection surfaces (12, 22) of the first and second watch parts (10, 20) on a fixing surface, At least one of the first and second connection surfaces (12, 22) or the third connection surface of any intermediate third part (30) is made of silicon oxidized by heat treatment so that the first and second watch parts are fixed to each other by the growth of a silicon oxide layer. Watch assembly.

2. The receiving opening (11) of the first watch part (10) has a constant cross-section over the entire first connection surface (12). The watch assembly according to claim 1.

3. The second watch part has a portion (25) of a variable radial cross-section that continuously increases from the boundary with the second connection surface (22), and the portion (25) of the variable radial cross-section is positioned outside the receiving opening (11) in the immediate vicinity of the end of the receiving opening (11). The watch assembly according to claim 1.

4. At least one of the first and second watch parts (10, 20) is mainly made of ceramic. The watch assembly according to claim 1.

5. The fixing surface or plurality of fixing surfaces of the first and second watch parts (10, 20) are cylindrical, oval, elliptical or polygonal, or are inscribed in a cylindrical, oval, elliptical or polygonal shape. The timepiece assembly according to claim 1.

6. At least one of the first and second timepiece components (10, 20) is mainly made of silicon, The first connection surface (12) of the first timepiece component (10) and the second connection surface (22) of the second timepiece component (20) are in direct contact, The connection surface of the component mainly made of silicon is made of silicon oxidized by heat treatment, The timepiece assembly according to claim 1.

7. The assembly includes an intermediate third component (30) mainly made of silicon having a sleeve shape, including a connection area that forms an external third connection surface and an internal third connection surface oxidized by heat treatment. The internal third connection surface is in direct contact with the second connection surface (22) of the second timepiece component (20), and the external third connection surface is in direct contact with the first connection surface (12) of the first timepiece component (10). The timepiece assembly according to claim 1.

8. The first timepiece component (10) includes at least one functional part separate from the receiving opening (11), The wall separating the receiving opening (11) of the first timepiece component (10) is connected to the functional part of the first timepiece component (10) by (i) a rigid connection or (ii) a flexible connection so as to remain substantially stationary with respect to the functional part. The timepiece assembly according to claim 1.

9. The fixing surfaces of the first and second timepiece components (10, 20) surround the second timepiece component (20) over at least 40% of its circumference. The timepiece assembly according to claim 1.

10. The first and second timepiece components (10, 20) have a shape in which the first and second timepiece components (10, 20) are assembled with a minimum gap before oxidation of at least one silicon connection surface by heat treatment. The timepiece assembly according to claim 1.

11. The receiving opening (11) of the first timepiece part (10) has a circular first cross-section, The connecting surface (22) of the second timepiece part (20) has a circular second cross-section, the diameter of the circular first cross-section being strictly larger than the diameter of the circular second cross-section before said oxidation by heat treatment, or one of said first and second connecting surfaces has a circular cross-section and the other has a non-circular cross-section so as to enable self-centering of said assembly of said first and second parts, or said two first and second cross-sections of said first and second connecting surfaces (12, 22) each have the same non-circular cross-section, The timepiece assembly according to claim 1.

12. The receiving opening (11) of the first timepiece part (10) is a through-opening or a blind opening, The timepiece assembly according to claim 1.

13. Said assembly includes at least one connecting surface (12, 22) of a timepiece part, either the first timepiece part (10) or the second timepiece part (20), structured so as to increase its own roughness, or including a knurling, a groove, a keyway, and / or a flat surface, and / or The second timepiece part (20) includes a support bearing surface (23). The timepiece assembly according to claim 1.

14. The connecting surface made of silicon oxide includes an oxide layer with an average thickness of 1 μm or more. The timepiece assembly according to claim 1.

15. The second timepiece part (20) is true so as to enable said timepiece assembly to be mounted with the ability to rotate within a timepiece movement. The timepiece assembly according to claim 1.

16. The first timepiece part (10) is a gear, or a pinion, or a hairspring. The timepiece assembly according to claim 1.

17. A timepiece movement comprising at least one timepiece assembly according to claim 1.

18. A timepiece comprising the timepiece movement according to claim 17.

19. A method for manufacturing a timepiece assembly, comprising a first timepiece part (10) and a separate second timepiece part (20), the method comprising: assembling the first and second timepiece parts (10, 20) in a minimum-gap intermediate configuration such that the second timepiece part (20) is positioned within a receiving opening or connection hole (11) of the first timepiece part (10), wherein a first connection surface (12) of the first timepiece part (10) is positioned opposite a second connection surface (22) of the second timepiece part (20) via internal and external third connection surfaces of an intermediate third part (30) optionally having a sleeve shape, and at least one of the first and second connection surfaces (12, 22) or the optional internal and external third connection surfaces is made of silicon; heat-treating the timepiece assembly in the intermediate configuration to obtain growth of a silicon oxide layer on the at least one connection surface made of silicon until a predetermined level of mutual fixation of the first and second timepiece parts (10, 20) is obtained; A method for manufacturing a timepiece assembly.

20. In the intermediate configuration, a radial gap between the first and second timepiece parts (10, 20) is 2 μm or less, and / or the second timepiece part (20) is inserted and held within an opening (41) of a support part (40) capable of withstanding the temperature of the heat treatment for holding the second timepiece part (20), or a plurality of second timepiece parts (20) are each assembled with a plurality of rough forms of the first timepiece part (10) temporarily joined on a wafer (5) used in the manufacturing. The method according to claim 19.

21. In the intermediate configuration, one end of the receiving opening (11) of the first watch part (10) abuts linearly, continuously or discontinuously, against a portion of the variable radial cross-section of the second watch part (10). The method according to claim 19.

22. The heat treatment is carried out at a temperature in the range of 800 to 1200 °C. The method according to claim 19.

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