Threaded watch components

Abstract

To provide a reliable threaded timepiece member made of fragile material.SOLUTION: A timepiece member 10 has a first axis A10 and a first thread 11 intended to cooperate with a second thread 21 provided on a second timepiece member 20, the first thread 11 being configured such that a contact area C between the first thread 11 and the second thread 20 extends less than 50% of the thread height h of the second thread 21 or configured such that the contact area C between the first thread 11 and the second thread 21 extends less than 0.3 times the pitch p of the first thread 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a threaded element for a timepiece. The invention also relates to a watch case having such a threaded element. The invention further relates to a timepiece having such a threaded element and / or such a watch case. [Background technology]

[0002] The watch case is subject to a number of constraints, particularly in terms of sealing, robustness and appearance, which must be implemented to prevent any unintentional and irreversible disassembly, which would result in after-sales service involving seal replacement, cleaning, lubrication and repair.

[0003] For parts with fragile mechanical behavior, such as back covers or bracelet links, which are made of ceramics (zirconia, alumina, composites, etc.), glass, sapphire, etc. and which must provide a seal and / or be able to be assembled and disassembled, traditional assembly methods are considered inappropriate.

[0004] In fact, brittle materials such as ceramics, glass, and sapphire have very good compressive strength but insufficient tensile strength. Therefore, threaded systems made from brittle materials are considered unsuitable for assemblies that are subject to high tensile loads. For example, if the tightening torque is too high, tension and / or shear stresses will be generated in the threads, leading to cracking or fracture of the threads.

[0005] For this reason, their use is essentially limited to areas where mechanical stresses are limited and where other properties of ceramics (chemical resistance, resistance to temperature extremes, magnetic resistance, biocompatibility, etc.) are exploited.

[0006] The known watch cases have one or more sealing elements made of natural or synthetic hard mineral materials, such as sapphire, ceramic, natural or shaped stones, etc. These materials are not ductile and have a limited ability to absorb shocks by deformation. This means that they have a lower resistance to tensile stress than metal parts with the same shape. In principle, this lower resistance to tensile stress is incompatible with the stresses to which the components in question are subjected (assembly, high pressure, etc.).

[0007] As described in particular in Patent Documents 1 and 2, metal back covers are traditionally screwed onto metal barrels. The threads are standardized, and both the internal and external threads comply with the same standard, ensuring the largest possible contact area between the threads.

[0008] To ensure a secure fit and minimize the risk of breakdowns, the metal caseback, combined with the metal body, is generally lubricated and tightened to a torque of between 1 and 6 N⋅m. This type of caseback may be required to withstand even higher pressures, especially when diving.

[0009] To ensure that the same assembly / disassembly tools can be used as for metal backs, the threads of brittle materials must withstand the same tightening torque, i.e., between 1 and 6 N·m. They must also withstand high pressures as a function of the intended tightness (e.g., tightness to 50 m, 100 m, 1220 m or 3900 m).

[0010] If ceramic threads are made to the same conventional standards, the tensile stresses caused by tightening and / or high pressures will exceed the strength of the ceramic, resulting in irreversible deformation, cracking or fracture, especially at the thread height.

[0011] Furthermore, a self-locking screw assembly system is known, as described in Patent Document 3, which has a threaded element with a nominal diameter of 1.5 mm or less and characterized by a second thread with an asymmetrical external pitch. The assembly complies, in particular, with the Swiss Watchmaking Standards (NIHS) and the in-house standards of each watch manufacturer. The continuous abutment between the assembly elements allows the tensile force to be distributed over the entire length of the threads of the abutting threaded parts, thereby reducing fatigue of the nut-screw system.

[0012] Each thread must meet a specific standard to ensure that both parts (inner and outer) of a threaded assembly correspond correctly and can withstand a specific load. Each thread is defined by its profile, which incorporates the diameter of the parts (outer diameter, inner diameter, etc.), the profile angle, pitch, and, if applicable, the helix angle.

[0013] Various standards, such as NIHS 60-30, ISO (e.g., EN 10226-1 or ISO 261), UN (e.g., ASME B1.1), Whitworth, British Standard (BSPT), American National, Pipe Thread, NPT, NPTF, DIN 405, MJ, UNJ, etc., define the shape of a thread, in particular the thread profile angle, pitch, and thread diameter.

[0014] The full specification gives the corresponding values ​​for the thread form and tolerances.

[0015] For example, the cross section of threads having NIHS, ISO and UN thread profiles is an equilateral triangle, meaning that each side of the thread (the angle between the sides) is 60°. According to a Whitworth thread, each side of the thread forms an angle of 55°.

[0016] Ceramic components are generally assembled to metal components by means other than a threaded fit within the ceramic, or by incorporating a metal threaded bushing onto the ceramic part to enhance the reliability of the threaded fit.

[0017] Patent document 4 describes a small watch case having a metal body and a ceramic back cover, which is fixed to the body by a screw that passes through the back cover and threads formed in the body.

[0018] Patent document 5 describes a small watch case with a metal body and a ceramic back cover: The ceramic back cover 1 is held to the body by a threaded metal clamping ring.

[0019] Patent document 6 describes an assembly suitable for fastening a ceramic or sapphire case back to a ceramic or metal body, especially a gold body. The article reveals that the very low ductility of ceramic materials precludes the use of conventional fastening methods, particularly direct screwing. To solve this problem, the aforementioned patent proposes a bayonet-type connection with a specific shape that compresses the ring. The choice of ring material determines the maximum tightening torque. For example, an amorphous alloy ring allows a tightening torque of approximately 3.2 N·m, which is typical for case backs screwed onto a body for a similar seal size.

[0020] Apple provides a small watch with a case (e.g., made of aluminum) and a cover (containing the biometric sensor) made of ceramic, sapphire, or tempered glass (ion-x glass). The cover "clips on" and is held in place by a PTFE seal.

[0021] Furthermore, assembly systems using screw threads (or threaded connections), also called "threaded systems", are routinely used to fasten at least two parts together. This type of threaded system is adapted to provide a permanent assembly during its useful life. Its advantages arise in particular from its simplicity (each assembly element forms part of the part to be assembled), its disassembly possibilities and the resulting applications.

[0022] Generally, a threaded system consists of a first threaded element, for example in the form of a screw, and a second threaded element, for example in the form of a nut, whose attachment consists of connecting the screw and the nut by applying a tightening torque during the screwing operation. Tightening the nut onto the screw allows the parts to be assembled in compression. The screw is therefore prestressed. The axial force acting on it is called tension. During screwing, a tightening torque is applied to the screw, allowing it to move helically within the nut, and when the parts come into contact, the screw is forced to stretch, placing it under tension. In this type of screwing method, the tension induced by tightening the nut onto the screw is related to the torque applied to the nut. The relationship between tension and torque is related to a number of parameters.

[0023] As such, each element of the threaded system is subjected to different types of mechanical stress, for example under tension, compression, shear, etc. [Prior art documents] [Patent documents]

[0024] [Patent Document 1] Swiss Patent Application Publication No. 1359773 [Patent Document 2] Swiss Patent Application Publication No. 486059 [Patent Document 3] International Publication No. 2013 / 072389 [Patent Document 4] European Patent Application Publication No. 0520224 [Patent Document 5] European Patent Application Publication No. 1916576 [Patent Document 6] European Patent Application Publication No. 3276432 Summary of the Invention [Problem to be solved by the invention]

[0025] The object of the present invention is to provide a threaded watch element which improves on known prior art elements and makes it possible to alleviate the above-mentioned problems. In particular, the present invention proposes a highly reliable threaded watch element made of brittle material.

[0026] The present invention allows for the easy replacement of a metal component with a ceramic component without requiring a change in the design of the second component with which the ceramic component is intended to cooperate. The present invention also allows for the maintenance of the same assembly / disassembly tools developed for assembling the metal components.

[0027] The timepiece element according to the invention is defined in claim 1.

[0028] Various embodiments of the timepiece element are defined in claims 2 to 5. 10 is defined as follows.

[0029] The watch case according to the present invention is 11 is defined as follows.

[0030] The embodiment of the watch case is as defined in claim 12 and 13 is defined as follows.

[0031] The watch according to the present invention is 14 is defined as follows. The miniature watch according to the invention is defined in claim 15.

[0032] An example of an embodiment of a watch is shown in the accompanying drawings. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 shows a first embodiment of a timepiece. [Figure 2] FIG. 2 shows the evolution of the maximum stress in the back cover (S1max) as a function of the root radius (R) of the back cover thread for different angles of the back cover thread. [Figure 3]FIG. 3 shows the evolution of the maximum stress in the back cover (S1max) as a function of the back cover thread root radius (R) for several assemblies with different characteristics in terms of back cover thread angle and barrel thread. DETAILED DESCRIPTION OF THE INVENTION

[0034] One embodiment of the watch 200 is described below with reference to FIG.

[0035] The timepiece 200 is, for example, a small timepiece, in particular a wristwatch.

[0036] The watch 200 includes a watch case 100. The watch case 100 is intended to receive a movement to protect the movement from the external environment. The case is preferably hermetically sealed.

[0037] The clock movement may be an electronic or mechanical movement, in particular an automatic movement.

[0038] The watch case comprises a first part 10 or first component and a second part 20 or second component, which are intended to be screwed together. In other words, these two parts each have a thread, and one of the two parts is screwed onto the other by the cooperation of two threads. These two threads therefore have the same pitch and, more generally, dimensional features that allow them to cooperate with each other.

[0039] Said first watch member 10 has a first axis A10 and further has a first thread 11 having a pitch p and intended to cooperate with a second thread 21 provided on the second watch member 20. The first thread 11 comprises: - adapted or configured such that the contact area C between the first thread and the second thread extends over no more than 50% of the thread height h of the second thread, or over no more than 30% of the thread height h of the second thread, or over no more than 15% of the thread height h of the second thread, or - adapted or configured such that the contact area C between the first threaded portion and the second threaded portion is over 0.3 times the pitch p, or over 0.2 times the pitch p, or over 0.1 times the pitch p, The range e of the contact area C is measured radially from the thread root 15 of the first thread portion to the first axis A10.

[0040] These geometric features preferably apply to all, nearly all, or the majority of the contacting threads, in other words, they do not apply only at the height of the threaded interface between the first and second members.

[0041] Each thread includes one or more threads and has a generally helical shape around the axis A10. Each thread is a helical portion, and its length measured along the axis is equal to the pitch. The thread root 15 is the junction between two flanks 16 of adjacent threads. The flanks 16 of a thread, i.e., the surfaces on either side of the thread, correspond to the portion located between the crest 14 and the root 15. The crest 14 is the portion where two flanks 16 of the same thread join.

[0042] The first threaded portion 11 preferably has a first thread angle 12 and the second threaded portion 21 preferably has a second thread angle 22, the value of the first thread angle 12 being 2° to 4° greater than the value of the second thread angle 22. The thread angle is defined as the angle formed by the two flanks of the thread at the height of the axial cross section of the threaded portion.

[0043] By adapting the dimensions of the threads of the first and / or second component, it is possible to propose assembling a first component made of brittle material to a second component having a standardized thread.

[0044] Whereas the threads of the prior art are designed to maximize the bearing surfaces of the two threads to better distribute the various forces acting on the interface height during assembly, so that the flanks of the threads of the two members are as parallel as possible, in this embodiment, one of the threads has a thread angle suitable for the flanks of the first thread portion of the first member to bear against or contact the flanks of the second thread portion of the second member at a contact area height that extends as close as possible to the root of the threads of the first thread portion, as described above. The contact area preferably extends over a length (measured radially relative to axis A10) of at most h / 2, or h / 4, or h / 8, where h corresponds to the thread height of the first thread portion or the thread height of the second thread portion.

[0045] The difference in thread angle between the first and second threaded portions must not seriously affect the behavior of the assembly, for example, strength, sealing, seizure, etc.

[0046] The change in the thread angle of the first threaded portion may be determined as a function of the nominal dimension of the second threaded portion so that the contact area between the two threaded portions moves in an appropriate manner (compared to an extended contact configuration where the two thread angles are the same).

[0047] For example, in a thread conforming to the ISO standard, increasing the thread angle of the first thread by 2° to 4° relative to the angle specified in the standard allows for a reduction in tensile stress of approximately 20%, as shown by the inventors' calculations. The thread angle of the first thread is therefore between 62° and 64°. With such dimensions, the contact dimension between the thread flanks of the first and second members is located in the lower part of the flanks of the first thread, near the root of the threads of the first member.

[0048] Alternatively or additionally, the threads of the first threaded portion may be truncated to reduce the contact area by 0.3 pitches or less in the thread height of the first threaded portion. This configuration prevents "point" bearing of the threads of the first threaded portion, which would cause increased stress due to leverage. In this embodiment, the thread angle between the first threaded portion and the second threaded portion is: - may be identical, or -As mentioned above, they may be non-identical.

[0049] The threads of the first threaded portion may be truncated so that the crest of the threads of the first threaded portion in axial cross section has a straight or convex shape.

[0050] The first threaded portion preferably has a thread root radius r that is greater than 0.2 times the pitch of the first threaded portion or greater than 0.4 times the pitch of the first threaded portion.

[0051] Optimizing the radius r of the thread root 15 can further contribute to reducing the tensile stress in the first member, as shown in the graphs of FIGS.

[0052] For a zirconia case back combined with a stainless steel barrel having standardized threads (ISO standard), Figure 2 shows the effect of the root radius of the thread on the stress experienced by the threads of the case back for various thread angles on the case back.

[0053] Figure 3 shows the use of threads with thread angles different from 60°. The choice of thread standard has only a small effect on the intended performance. Mainly, the use of larger angles, 2° to 4° more than the normal value, on the back thread allows for stress reduction, while developing thread angles of 55° or 65° has only a small effect.

[0054] If the first part is a screw-type part, the first thread is preferably connected to the bearing surface 5 via a connecting fillet 13 having a radius greater than 0.4 times the pitch p of the first thread or greater than 0.8 times the pitch p of the first thread. This bearing surface extends radially outward from the first thread and is intended to bear against a second surface 25 provided on the second watch part. For example, a seal may be arranged between the two surfaces to provide a seal between the two parts.

[0055] For example, the connecting fillet 13 forms part of a groove or recess having two groove walls and a groove bottom, forming a connection between the bearing surface 5 and the first threaded portion 11. On the thread side, the first groove wall may have a straight and / or curved axial cross section, the curvature of which may be defined by a groove radius 18a. On the bearing surface 5 side, the groove may have a straight and / or curved axial cross section, the curvature of which may be defined by a groove radius 18b.

[0056] The groove base may have a "point" axial cross section, i.e., the axial cross section may be the point where the axial cross sections of the two groove walls intersect. Alternatively, the groove base may be more extensive, as shown in Figure 1, which illustrates an example in which two curved sections 18a and 18b are connected by a straight cross section.

[0057] The first member is also subjected to tensile stress in the vicinity of the groove.

[0058] In a watch case-type component, typically a case back-body assembly, the metal first member has a thread groove radius 18a and bearing surface radius 18b that are between 0.06 mm and 0.15 mm, with a nominal value of 0.05 mm.

[0059] The thread groove radius 18a and the bearing surface radius 18b may be the same or different.

[0060] When the thread groove radius 18a increases from 0.1 mm to 0.2 mm, the mechanical stress value decreases by approximately 20%. When the thread groove radius 18a increases from 0.1 mm to 0.4 mm, the mechanical stress value decreases by approximately 40%.

[0061] The connecting angle between the groove and the bearing surface may be right, acute, or obtuse, with or without pitting of material.

[0062] The connection between the groove and the bearing surface may be flat or concave, which does not affect the tensile strength of the groove.

[0063] The second threaded portion 21 is preferably standardized, in particular according to ISO, NIHS, UN, BSPT, NPT, NPTF, DIN, MJ, UNJ or Whitworth profile.

[0064] In the example shown in FIG. 1, the first threaded portion is an external threaded portion, i.e. formed on a protruding surface, for example the surface of a shaft.

[0065] In the example shown in FIG. 1, the second threaded portion is an internal threaded portion, i.e. formed in a concave surface, for example the surface of a hole.

[0066] In the example shown in Figure 1, the first component is a back cover made of a brittle material, in particular ceramic, sapphire, zirconia or glass, the first thread of which is subjected to a tensile load. The back cover is assembled to a second component consisting of a body, which is made of a more ductile material, in particular a metal or metal alloy.

[0067] For example, consider the following configuration: the first watch part 10 is the back cover and the second watch part 20 is the case or inner case, or the first watch part 10 is a case or inner case and the second watch part 20 is a case back, or - the first watch member 10 is the case and the second watch member 20 is the inner case, or - the first watch member 10 is the inner casement and the second watch member 20 is the casement, or the first timepiece member 10 is the crown and the second timepiece member 20 is the crown tube, or the first timepiece member 10 is a crown tube and the second timepiece member 20 is a crown, or the first timepiece member 10 is a crown and the second timepiece member 20 is a crown cap, or the watch element 10 is a valve tube and the second watch element 20 is a valve, or the clock element 10 is a collector tube and the second clock element 20 is a collector, or the first watch element 10 is a cap and the second watch element 20 is a crown, a crown tube or a central hour wheel, or The first watch member 10 is a screw and the second watch member 20 is a link of a bracelet.

[0068] The present invention can replace any type of screw fastening in which an assembly is produced by cooperating a first part made of a brittle material, in particular ceramic, sapphire, zirconia, or glass, with a second part made of a more ductile material, in particular metal or a metal alloy. The present invention can also replace any type of screw fastening in which an assembly is produced by cooperating a first part made of a brittle material, in particular ceramic, sapphire, zirconia, or glass, with a second part made of a brittle material, in particular ceramic, sapphire, zirconia, or glass. For example, the first and second parts are screwed together and subjected to mechanical stress, and the parts that make up the screw are subjected to, for example, tension as the mechanical stress.

[0069] When arranging or installing a threaded assembly, i.e. when threading a first and a second member together by rotating one of the members about axis A10, it is of utmost importance to apply a tightening torque that produces the appropriate mechanical stress, in particular an appropriate tension that makes it possible to take into account the factors of the first and second members that abut against each other and compensate for any additional forces caused by shock, vibration, pressure, sources of expansion or contraction, temperature or humidity changes, etc.

[0070] The applied tightening torque must be extremely careful, especially in the case of sealed or safety assemblies: if it is too low, the system risks leaking or loosening; if it is too high, the components, especially one of the threads, may be damaged or destroyed.

[0071] Curves for common materials make it possible to determine the limiting values ​​that must be adopted before the nut and screw combination is damaged for a given material and a given standard reference configuration, for a given dimension. However, no such curves exist for material combinations involving metal alloys and brittle materials such as ceramics, sapphire, zirconia or glass.

[0072] When the components of a threaded assembly are tightened together, only a portion of the screw / clamping force contributes to true tightening (deformation of one or both components along the helical connecting axis), while the remaining force is distributed by friction, especially in the threads. Friction is necessary to prevent loosening over time. However, these mechanisms can cause the assembly to seize if the friction is too high.

[0073] The seizure threshold of a material combination is defined by the contact pressure at which material transfer occurs from one surface to the other. For each material combination, there is a seizure threshold. In addition to the surface condition, the threshold depends on the chemical and / or metallurgical properties of the two materials in contact.

[0074] In the case of threaded assemblies, seizure can occur in two stages: micro-seizure followed by full seizure where applicable.

[0075] Microseizure occurs when tension does not increase linearly, but in steps as the tightening torque increases. This is the case, for example, when a microweld forms and is immediately destroyed by the tightening torque ("stick-slip" phenomenon). Relative rotation between the elements is still possible, but tightening is prevented. This phenomenon can be locally limited.

[0076] Micro-seizure generally becomes more pronounced as the tightening torque increases, eventually leading to complete seizure, which prevents all rotation.

[0077] A prestressed threaded assembly can be disassembled as long as no seizure has occurred between the parts after tightening. This means that certain precautions must be taken to ensure that the threaded assembly can be disassembled, especially to prevent micro-seizure during the initial tightening, to prevent any corrosion during use, and to maintain the correct coefficient of friction throughout the life of the assembly.

[0078] It is therefore necessary to find solutions that limit friction in order to make the torque / tension relationship in the assembly as constant as possible. Based on measurements or curves, it is possible to determine at what tightening torque a seizure can occur. Indeed, given that this coefficient of friction must be constant, from a certain torque value a significant increase in said coefficient will reveal the seizure phenomenon. To increase the seizure threshold, it is necessary to influence the friction at the height of each abutting surface of the assembly.

[0079] Stainless steel, aluminum, and titanium threads are particularly susceptible to seizure.

[0080] To minimize or prevent these losses, stainless steel assemblies are commonly treated, for example with lubricants or "anti-seize" coatings. These treatments are subject to deterioration over time.

[0081] For stainless steel backs assembled to stainless steel cases without lubrication, seizure problems are already evident at tightening torques of 3 N·m or less.

[0082] It has been found that ceramic components, such as zirconia components, according to the present invention have a lower likelihood of seizure than the metal components they replace. Even without any treatment of the metal parts, no seizure or deformation was observed in the zirconia components at a tightening torque of 5 N·m.

[0083] The above solution makes it possible to prevent seizure between the elements of the threaded system, especially during tightening, and ensures that the assembly can be disassembled.

[0084] The system can also withstand higher tightening torques without seizing: for example, when a torque of 10 N·m is applied to a zirconia back cover according to the present invention assembled to a stainless steel body, the component does not begin to seize or deform, even when the metal parts are not treated.

[0085] Alternatively, instead of a thread made of a brittle material, the thread may be a ceramic-coated metal thread, i.e., the threaded surface of the thread is made of a ceramic coating. The ceramic coating may be obtained by ceramic spraying, surface treatment, heat treatment, or other suitable techniques. In this case, the present invention makes it possible to minimize the risk of cracking or chipping of the ceramic layer and seizure of the assembly. The substrate may be, for example, stainless steel, titanium, etc. The ceramic layer may be, for example, an oxide ceramic (zirconia, alumina, aluminum titanate, etc.) or a non-oxide ceramic layer, such as a nitride or carbide (aluminum nitride, silicon nitride, silicon carbide, tungsten carbide, etc.).

[0086] Thanks to the invention, it is possible to provide interchangeable back covers made of brittle materials or metal alloys that have the same or substantially the same geometric shape and that cooperate with the same body, in particular the same metal body, and these back covers can be installed without modifying the manufacturing or after-sales tools for installing and removing the back covers, regardless of the material from which they are made.

[0087] Thanks to the invention, it is possible to produce a hermetically sealed watch case with a metal back cover replaced by a brittle material, in particular ceramic, sapphire, zirconia or glass, without having to adapt the metal body.

[0088] Thanks to the invention, it is possible to modify the threads of a back cover made of brittle material in order to maintain the same integrity as a metal back cover during screwing, tightening and use, and furthermore, the seizure problems faced by metal back covers are avoided, even when higher tightening torques than are normally used for metal alloy back covers are used.

[0089] Thanks to the invention, it is possible to determine dimensions of threads, especially those made of brittle materials, that allow the threads to withstand the same range of stresses as the metal part they replace and that are compatible with standard threads, such as threads according to the Swiss Watchmaking Standards (NIHS).These dimensions take into account the magnitude of the stress field and the possibility of fracture of the brittle material component.

[0090] With the intention of being able to provide a ceramic back cover, there are in fact advantages to solutions for dimensionally determining threads made of brittle materials, in particular ceramic materials, that are compatible with standard threads and allow parts made of brittle materials to be assembled by screwing. A ceramic back cover mounted on a metal barrel with threads having increased strength offers one example of such advantages, especially in relation to stresses induced by assembly and / or the environment, for example compression of the assembly during diving.

[0091] The design advantageously allows a metal back to be easily replaced with a ceramic back without having to change the design of the metal parts that receive the back and / or the tools that attach / remove the back, while ensuring a compatible seal, reliable assembly and minimal risk of seizure.

[0092] On the contrary, according to the prior art, the male and female threads are machined according to the same class and with the same tolerances so as to fit together and to maximize the contact area between the male and female threads. When the male and female threads are machined according to the same class, taking into account the tolerances, the flanks of the female thread and the male thread contact each other over the largest possible area, and the flanks are as "flat" as possible. Based on these dimensions, the prior art aimed to assemble, in particular to suppress the phenomena of stripping and seizing of the threads, and to optimize the strength of the assembly.

[0093] According to another aspect of the invention, an assembly, in particular a watch case, comprises: a first part 10 made of a brittle material, in particular ceramic or sapphire or zirconia or glass, or having a threaded surface made of a brittle material coating, in particular ceramic or sapphire or zirconia or glass coating, and a second member 20, in particular made mainly of metal or metal alloy;

[0094] The first and second members are advantageously connected by a threaded connection or screwed together.

[0095] According to this other aspect of the invention, a timepiece comprises an assembly as described above.

[0096] The alternative aspects of the invention described above may include any combination of the features described in this specification, unless there is a logical or technical incompatibility. [Explanation of symbols]

[0097] 5 Support surface 10 Watch components A10 1st axis 11 First screw part 12 First thread angle 13 Connecting Fillet 15 base 20 Second watch component 21 Second screw part 22 Second thread angle 100 watch cases 200 watches

Claims

1. A watch element (10) having a first axis (A10) and a first thread (11) with a pitch (p) intended to cooperate with a second thread (21) provided on a second watch element (20), said first thread being configured such that the contact area (C) between said first thread and said second thread extends over less than 50% of the height (h) of the thread of said second thread, or such that the contact area (C) between said first thread and said second thread extends over less than 0.3 times said pitch (p), said extent (e) of said contact area being measured radially from the root (15) of the thread of said first thread to said first axis (A10). Clock element (10).

2. The first threaded portion (11) has a first thread angle (12), and the second threaded portion (21) has a second thread angle (22), and the value of the first thread angle (12) is 2° to 4° greater than the value of the second thread angle (22).

2. The timepiece member according to claim 1.

3. The height of the thread of the first threaded portion is less than 0.3 pitches.

3. A timepiece member according to claim 1 or 2.

4. the first threaded portion has a thread root radius (15) greater than 0.2 times the pitch of the first threaded portion or greater than 0.4 times the pitch of the first threaded portion; A timepiece member according to any one of claims 1 to 3.

5. the first threaded portion is connected to the bearing surface (5) by a connecting fillet (13), the connecting fillet (13) having a radius (18b) greater than 0.4 times the pitch of the first threaded portion or greater than 0.8 times the pitch of the first threaded portion; A timepiece member according to any one of claims 1 to 4.

6. The second thread portion is a standardized thread.

6. A timepiece member according to any one of claims 1 to 5.

7. The second thread portion has a thread conforming to ISO standard, NIHS standard, UN standard, BSPT standard, NPT standard, NPTF standard, DIN standard, MJ standard, UNJ standard, or Whitworth profile. A timepiece member according to any one of claims 1 to 5.

8. The clock element (10) is made of a brittle material, or the clock element (10) is made primarily of a metal or metal alloy and the first threaded portion has a surface made of a brittle material coating. A timepiece element according to any one of claims 1 to 7.

9. The clock member (10) is made of ceramic, sapphire, zirconia, or glass. A timepiece element according to any one of claims 1 to 7.

10. The watch member (10) is a case back and the second watch member (20) is a case or inner case; or said watch element (10) being a case or inner case and said second watch element (20) being a case back; or said watch member (10) being a case and said second watch member (20) being an inner case; or said watch member (10) being the inner casement and said second watch member (20) being the casement; or The timepiece member (10) is a crown and the second timepiece member (20) is a crown tube; or The timepiece member (10) is a crown tube and the second timepiece member (20) is a crown; or said timepiece member (10) being a crown and said second timepiece member (20) being a crown cap; or said timepiece member (10) is a valve tube and said second timepiece member (20) is a valve; or said timepiece member (10) being a collector tube and said second timepiece member (20) being a collector; or The timepiece member (10) is a cap and the second timepiece member (20) is a crown, a crown tube or a central barrel; or The watch member (10) is a screw and the second watch member (20) is a bracelet link. A timepiece element (10) according to any one of claims 1 to 9.

11. A case (100) for a watch part (200), comprising a first watch member (10) which is a watch member described in any one of claims 1 to 10, another watch member (20), and / or another watch member which is screwed onto or within the first watch member.

12. A watch having a case (20) and a back cover (10) that is a timepiece component according to any one of claims 1 to 10. Case (100) of a watch (200).

13. A case back (20) and a watch body (10) that is a watch component according to any one of claims 1 to 10. A case (100) for watch parts (200).

14. A case (100) for a timepiece component according to any one of claims 1 to 10 or a timepiece (200) according to any one of claims 11 to 13, Clock (200).

15. A case (100) for a timepiece component according to any one of claims 1 to 10 or a timepiece (200) according to any one of claims 11 to 13, Small clock.

Images