CH708925A1 - diamond mechanical room to watch movement. - Google Patents

Abstract

Mechanical piece (3) functional diamond watch movement, made entirely of monocrystalline diamond.

Description

Technical area

The present invention relates to a mechanical part for watch movement, for example a wheel, a pinion, an anchor wheel, an escapement anchor, a spiral spring, or another micro-mechanical functional component in the regulating organ, in the cog or in a complication of the movement. The present invention relates in particular to such a piece made of diamond.

State of the art

[0002] Mechanical parts for mechanical watch movements are most often made of metal. The moving parts, for example the axles, the wheels, the gears, the anchor of escape, the escape wheel, the balance and the spiral are frequently made of steel, or steel elinvar for the spiral. The plate and bridges are usually made of brass or steel. Other components are used more marginally, for example rubies for bearings or pallets, or ceramics for some bearings.

[0003] Extensive research has been conducted to replace these conventional materials and to avoid some of their disadvantages. For example, silicon is today used industrially for the manufacture of the bodies of the escapement or spiral in particular. EP 732 635 A1 (CSEM) discloses a micro-mechanical part, for example an anchor for a watch movement, cut in a silicon wafer by etching by means of a plasma gas around a mask formed previously on the face of the plate.

Silicon has the advantage of being easy to machine, reproducibly, with technologies perfectly mastered for the manufacture of integrated circuits or MEMS in particular. However, it has certain disadvantages, including an insufficient tribological surface state and a relatively high coefficient of friction.

[0005] CH 669 109 A1 (The Swatch Group R & D Ltd) suggests improving this surface state by depositing a layer of carbon DLC ("Diamond Like Carbon") on the silicon. Similarly, US 2002/114 225 (Damasko) describes in particular a steel exhaust anchor coated with a DLC ("Diamond Like Carbon") layer. US 2012/0263909 (Diamaze Microtechnology SA et al.) Discloses another example of a diamond coated mechanical part or a DLC layer.

[0006] DLC coatings have some of the properties of natural diamond, although their crystalline structure is very different. In general, these coatings are produced using a method of carbon deposition by plasma, filtered arcs, ion beams, cathode sputtering, and the like. These fast, high energy processes do not allow the carbon atoms to be arranged according to the typical sp3 cubic disposition of the diamond; the arrangement of the atoms is globally amorphous, with an entanglement of crystalline micro-structures oriented differently from each other.

Furthermore, the known DLC coating deposition processes generate a material having significant proportions, greater than 10%, of hydrogen, graphitic carbon or other components.

A piece of steel or silicon coated with a DLC layer thus has tribological surface conditions which are certainly improved, but still far from perfect. The adhesion of the DLC coating to the substrate is also a weak point. In any case, the additional step required for the deposition of this DLC layer complicates the manufacture. Moreover, it is difficult to precisely control the shape of the part after the deposition of the coating.

[0009] Micromechanical parts made of diamond are also known. Thus, WO 2004/029 733 A2 (Fore Eagle Co Ltd) describes watch components made at least partially in this material. This document lists various advantages of diamond, including its hardness, low coefficient of friction, good impact resistance, high mechanical strength, high modulus of elasticity, low coefficient of thermal expansion, transparency and the ability to not get scratched.

[0010] EP 2 407 831 A1 (Rolex SA) describes a hairspring for a watch oscillator which can be made of a low-density material such as silicon, diamond or quartz. The spiral can be made by a process of chemical etching using a plasma ("DRIE, Deep Reactive Ion Etching").

CH 701 155 B1 (Complitime SA) describes a pendulum for a timepiece comprising a board that can be diamond, quartz, silicon or corundum.

[0012] WO 2005/017 631 (Fore Eagle Co Ltd) describes another rocker made of diamond and obtained by chemical etching using a plasma.

EP 2 107 434 A1 discloses a mechanical part, including an anchor wheel for watchmaking, silicon or diamond.

EP 2 233 989 (Ulysse Nardin Le Locle SA) describes a spiral spring diamond obtained by deep etching.

CH 701 369 discloses a diamond barrel spring.

The type of diamond used for the above parts is generally not specified in these documents. In practice, it is always polycrystalline synthetic diamond whose cost is 10 to 50% lower than that of natural diamond, and which can be produced in forms suitable for the intended use.

We know different methods of manufacturing synthetic diamond. US 8,088,221 B2 (Z. Shapiro) discloses a low temperature and relatively low pressure synthetic diamond manufacturing process. EP 2 189 555 A2 (Appollo Diamond Inc) discloses another method for producing synthetic diamond. CVD or explosive detonation methods have also been suggested.

Brief summary of the invention

However, there is a need, especially in the mid-range and high-end watch industry, for micromechanical components made of materials offering a better compromise between the desired properties of hardness, mechanical strength, lightness, low expansion. thermal stability, modulus of elasticity, and high precision machining facility.

An object of the present invention is therefore to provide a mechanical part for watch application that offers such a compromise between these different properties.

Another object is to provide a mechanical part in a material that is perceived as more noble than steel, silicon or polycrystalline synthetic diamond.

According to the invention, these objects are achieved in particular by means of a functional mechanical diamond watch movement, made entirely of monocrystalline diamond.

By functional mechanical part is meant in the present application a part that performs a mechanical function, so that it is not possible to remove this part without affecting at least one function of the watch movement. A purely decorative piece, or a piece of watchmaking clothing, is therefore not considered as a functional mechanical part.

A piece is said to be "made entirely of diamond" if it consists of a single diamond crystal, without a substrate in another material, without surface coating and generally without assembly. Small quantities of impurities, for example less than 3%, can at most be present, in particular in the case of natural diamonds, but also of synthetic diamonds. The impurities may for example be constituted by doping.

A diamond is considered monocrystalline if it consists of a single crystal, or essentially a single crystal with the exception of a limited number of distinct crystals, often smaller than the main crystal, unwanted but which result for example from the manufacturing process or imperfect crystallization around impurities or edges.

The invention in particular based on the finding that monocrystalline diamond has many advantages over more widespread polycrystalline diamond, and even more compared to DLC coatings.

In particular, monocrystalline diamonds have the advantage over polycrystalline diamonds to be extremely strong; no split primer exists between the different grains. This strength allows to achieve with the same strength of the finer parts and therefore lighter. For example, it is possible to make monocrystalline diamond parts such as, without limitation, anchor wheels or anchors with a thickness less than 120 microns, preferably less than 100 microns, for example between 20 and 60 microns. Such thicknesses would not be practically achievable with steel, silicon or polycrystalline diamond parts, because these parts would be too fragile and very difficult to mount without breaking them.

With this extreme finesse, it is possible on the one hand to reduce the thickness of the movement, and especially to reduce the inertia of moving parts. This makes it possible to increase the power reserve of the watch, and to increase the frequency of oscillation of the regulating organ.

On the other hand, monocrystalline diamonds generally have a smoother surface finish than polycrystalline diamonds or DLC coatings, whose grain structure does not provide an optimal tribological surface,

The polycrystalline diamonds known in the prior art for the manufacture of mechanical parts are extremely hard, harder than the usual natural monocrystalline diamonds. However, contrary to prejudices, such a high degree of hardness is not always necessary or even advantageous for a watch component. This hardness results in a high polishing cost, and faster wear of the less hard parts in contact.

The mechanical part made of monocrystalline diamond may be a flat piece, for example a part used in the regulating member of a mechanical watch, for example an anchor or an anchor wheel.

The mechanical part may be a flat piece made by cutting from a flat plate.

The cutting of the plates can be performed by laser from a non-flat diamond. The laser can be tilted during cutting. The direction of the laser can be changed by means of a mirror during cutting. Cutting can be done from both ends of the piece.

The cutting of flat parts in a plate can be performed from a laser oriented perpendicularly to the plate. The cutting path can be defined by means of laser path control software. The trajectory can be optimized to minimize the risk of cracking in any direction other than the cutting direction. The trajectory can be optimized by taking into account the shape and size of the laser beam. Polishing thickness indicators can be cut to control the depth to which the part should be polished later.

The mechanical part may be a multi-level flat part obtained by thermochemical etching from a flat piece at a single level.

The flat mechanical part may be a spiral spring for the regulating member of a mechanical watch. The high rigidity of monocrystalline diamond makes it possible to obtain high oscillation frequencies with small diameter spirals.

The mechanical part can also be a pallet intended to equip an exhaust anchor in another material, for example a steel anchor.

The mechanical part can also be an organ of the escapement or the regulating organ of the watch, for example an anchor, an anchor wheel or a rocker arm.

The piece can be made of natural or synthetic monocrystalline diamond.

Monocrystalline natural diamonds of dimension compatible with the manufacture of mechanical parts have the reputation of being very expensive, so that there was a very important prejudice against their use for the manufacture of such parts. However, it has been found that many natural monocrystalline diamonds are discovered each year with shapes that do not allow to cut them for use in jewelery, for example. Such diamonds are most often split to reduce them to usable smaller diamonds, or reduced to diamond powder for industrial applications. The value of such pieces is therefore much lower than that of diamonds usually used in watchmaking and jewelery.

Synthetic diamonds are in the vast majority of polycrystalline cases; it is generally considered difficult to produce monocrystalline synthetic diamonds, especially large diamonds. It has, however, been observed more recently that the evolution of technologies makes it possible to manufacture monocrystalline synthetic diamonds of more than 1 carat at relatively low costs.

Monocrystalline synthetic diamonds can for example be obtained by growing carbon by CVD deposition around a monocrystalline diamond primer. The monocrystalline diamond primer can be reused to successively grow several monocrystalline synthetic diamonds. It is important that the primer is monocrystalline diamond so that the structure that is deposited is itself monocrystalline. Carbon can be obtained from methane in a CVD reactor.

Monocrystalline synthetic diamond can also be obtained by compression of carbon at high pressure and high temperature. This solution, however, results in higher costs, especially for the manufacture of monocrystalline diamonds of large dimensions.

Polycrystalline diamonds are most often transparent or gray; because of the multiple interfaces between different crystal grains with different orientations, they produce little or no glare, and virtually no iridescence effects.

In contrast, monocrystalline diamonds, especially natural monocrystalline diamonds, exist in a wide variety of colors, including transparent, black, blue, yellow, red, etc. On the other hand, the play of light that is reflected on different faces oriented in various ways produces very popular iridescence effects.

The synthetic monocrystalline diamond can be doped. Natural monocrystalline diamond can be doped.

The doped monocrystalline diamond is obtained by deliberately introducing a doping element into the diamond, either during the growth of a synthetic diamond or in a synthetic or natural diamond already formed.

The doping operation thus makes it possible to produce a diamond that is different from the diamonds found in nature, and different from undoped synthetic monocrystalline diamonds. The difference comes from the type of impurities, their distribution and / or their concentration. The doping is chosen so as to modify the mechanical and tribological properties of the diamond piece.

The doping of the synthetic monocrystalline diamond can be obtained during its manufacture by adding impurities in the gas of the CVD reactor. This doping can be carried out practically without additional cost during the growth of a monocrystalline synthetic diamond.

The doping of synthetic or natural monocrystalline diamond can also be obtained by implantation of ions by means of a high energy beam.

The doping can be homogeneous throughout the volume of the room.

The doping may be limited to the surface, or different in surface and depth. Doping may be chosen to control the hardness and / or color and / or elasticity and / or sensitivity of the Young's modulus to temperature. Different monocrystalline diamond pieces of the same movement can be doped differently.

In one embodiment, the piece is made from a flat plate but in which facets are cut on the upper face and / or lower, in order to lighten and / or create effects of iridescence.

The invention also relates to a watch movement comprising one or more functional mechanical parts in monocrystalline diamond.

Different mechanical parts of the same movement can be made in different varieties of monocrystalline diamond. For example, different mechanical parts of the same movement can be made in different colors of monocrystalline diamond. It has been pointed out in the context of the invention that the color of the monocrystalline diamond, which is due to the impurities, influences its hardness. For example, transparent monocrystalline diamond is less hard than black monocrystalline diamond doped with boron ions. The type or color of monocrystalline diamond chosen for different pieces of the same movement is therefore determined according to the desired hardness, or according to other mechanical properties depending on this color.

In order to reduce wear, it is advantageous that the pallets of the escapement anchor, or the complete anchor if the pallets are integrated, are harder than the anchor wheel with which they collaborate; an anchor wheel lasts less than the pallets makes it possible to absorb shocks. In one embodiment, the watch movement comprises, for example, an anchor or pallet of anchor in a hard monocrystalline diamond, and an anchor wheel in a less hard monocrystalline diamond. The anchor or the pallets may be, for example boron-doped black monocrystalline diamond while the anchor wheel may be transparent or yellow monocrystalline diamond.

The mechanical part may comprise upper and lower faces substantially flat and parallel to each other, or inclined to create iridescent reflections.

At least a portion of these upper and lower surfaces can be polished, for example with diamond powder or on a grinding wheel with diamond powder.

The mechanical part may further comprise lateral surfaces. At least a part of these mechanical surfaces can be polished or corrected, for example with a laser beam or an ion beam. Advantageously, at least a portion of these surfaces is corrected in order to have a better tribological state than before the correction. At least one portion may be corrected so that this portion is substantially perpendicular to the lower and upper faces of the part.

The piece can be held by vacuum during polishing. It can thus be positioned very precisely in height, and inaccuracies in the thickness of the part which result from an unmaintained thickness of glue in the methods of polishing glued parts used in the prior art are avoided.

At least one of the surfaces of the part may be heat treated, for example by exposing it to a temperature between 600 ° and 750 ° C., preferably between 650 and 680 ° C., in order to burn the carbon in the form of graphite produced by the cutting of the diamond and which remains possibly on the surface. This heat treatment also makes it possible to polish the diamond, by burning tips on the surface, without however degrading the surface state by a high temperature attack.

At least one of the surfaces may be ground using a laser.

The state of at least one surface of the diamond is advantageously treated both by heat treatment, mechanical polishing and laser grinding.

The piece can be polished until the surface is level with polishing marks previously cut.

The workpiece can be ultrasonically polished. It can be cleaned with gasoline.

Brief description of the figures

Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which:

Figs. 1A to 1E illustrate different successive steps of a method of manufacturing a mechanical part according to the invention.

FIG. 2 illustrates an example of a mechanical part according to the invention.

Figs. 3A to 3B schematically illustrate a polishing or grinding operation of at least a portion of the lateral flanks of a workpiece according to the invention.

Example (s) of embodiment of the invention

Figs. 1 to 3 schematically illustrate a method of manufacturing a functional mechanical part according to the invention.

FIG. 1A illustrates an uncut monocrystalline diamond 1 used to manufacture one or more pieces according to the invention. The monocrystalline diamond may be a natural diamond or a synthetic diamond, with a weight advantageously greater than 1 carat, preferably greater than 3 carats.

In the case of a natural diamond, it may be a diamond having a shape or other properties rendering it unfit for recovery for use in jewelery.

A synthetic monocrystalline diamond can be produced for example by means of a filtered arc to deposit carbon on a monocrystalline diamond primer, without the addition of hydrogen or other materials. Another possibility is to make a CVD deposit of carbon produced from a hydrocarbon such as methane on a monocrystalline diamond primer. The primer can be reused after cutting plates in the mass deposited above the primer.

A third, less advantageous, possibility is to produce a synthetic monocrystalline diamond by subjecting a carbon source to a high temperature and a high simultaneous pressure. Other methods may be used.

The monocrystalline diamond thus formed can be doped. In one embodiment, the doping product can be introduced during the formation of the synthetic diamond, for example by adding traces of dopant in the filtered arc respectively in the CVD reactor. In another embodiment, the dopant is added after formation of the synthetic diamond, for example by means of a high energy ion beam. The doping can be carried out homogeneously throughout the mass of the diamond, and / or only at the surface. A first doping may be carried out in the mass and a different doping, for example with another doping product and / or with another concentration, may be carried out on the surface.

The doping can be selected in order to modify the hardness of the pieces produced from this diamond; depending on the doping product, it is possible to increase or reduce this hardness. Doping can also be selected to control the color of the diamond. Doping can be chosen to control the Young's modulus of the diamond. The doping can be chosen so as to reduce the sensitivity of the Young's modulus to the temperature, in order to produce parts whose rigidity is as independent as possible from the temperature. The doping can be chosen so as to reduce the coefficient of expansion of the diamond, in order to produce pieces whose dimensions are as independent as possible from the temperature.

The doping product and the concentration of this product are further selected so as not to interfere with the monocrystalline diamond structure, or to minimize this interference. In one embodiment, the diamond is doped with boron ions. Different diamonds used for the production of different pieces in the same watch can be doped differently depending on the desired properties.

The boron doping performed during the organic growth of the synthetic diamond has the advantage of producing a non-radioactive black diamond, unlike doping processes by introducing high energy ions.

Monocrystalline diamond 1 is then cut as shown in FIG. 1B, for example by means of a diamond saw, or slit by means of a hammer and a blade, an electric arc, an ion beam, or preferably cut by means of a laser to obtain a planar surface. The laser is advantageously a pulsed laser, for example a laser pulsed at a frequency of 5 to 40 GHz.

In the embodiment illustrated in FIGS. 4A to 4C, the diamond is sliced from a first side by means of a first laser beam 20. The laser beam is rotated by means of a movable mirror, so as to emit in a cone with an opening angle less than 5 °. The diamond is then etched from the other side by means of another laser beam 21 rotated in a cone (Fig. 4B). It is also possible to use the same laser beam to attack both sides of the room, by turning it between the two cuts. This cone machining allows the ablation zone to be enlarged and to avoid poor surface conditions and the destruction of the crystalline structure which may occur if the ablation is performed in a narrow channel, causing a rise in excessive temperature. The process is comparable, proportionately, to that of a lumberjack cutting a trunk by means of two notches sloping from each side of the trunk.

The convex surface thus produced by this cutting is then rectified or flattened, as shown in FIG. 4C, by means of a laser beam oriented parallel to the surface of the plate that is to be produced. The pulsation frequency of this laser can be for example between 10 and 100 KHz, to obtain a precise cut without the problems of changes in the crystalline structure caused by the high energy lasers pulsed more quickly.

It is possible to scan the rough diamond in advance using a 3D scanner to determine the optimal cutting plane to obtain the maximum of parts 3 and / or facilitate cleavage; for example, a tetrahedral section of the crystal will be preferred because it is faster and provides a cleaner surface.

In a first embodiment, the section plane is determined in order to obtain an active surface of the workpiece oriented along the {111} crystalline plane, which is generally the hardest. In the case of a plate intended for the manufacture of a clockwork spiral spring, the cutting plane is preferably parallel to the {111} plane of the diamond. In the case of a plate intended for the manufacture of pallets for a watch anchor, the plane of section is preferably distinct from the plane {111} and chosen so as to allow the cutting of pallets whose impulse surface, obtained in the slice of the cut plates, is parallel to the {111} crystalline orientation plane.

However, it has been found in the context of the invention that even if the crystalline plane {111} is the hardest, this hardness decreases very abruptly in case of slight deviation from this ideal plane. For example, a piece cut or polished in a plane that deviates even a few degrees from the plane {111} has a significantly reduced hardness and surface condition. However, it is difficult, especially in the context of industrial manufacture, to manufacture parts with surfaces oriented precisely along the {111} plane, without any deviation.

Therefore, in a preferred embodiment, the section plane is determined in order to obtain an active surface of the workpiece oriented substantially along the {001} crystalline plane or along the {011} plane; although less hard than the ideal plane {111}, these planes are less sensitive to deviations from the ideal surface. In the case of a plate intended for the manufacture of a clockwork spiral spring, the cutting plane is preferably substantially parallel to the {001} or {011} plane of the diamond. In the case of a plate intended for the manufacture of pallets for a watch anchor, the cutting plane is preferably chosen so as to allow the cutting of pallets whose impulse surface, obtained in the edge of the cut plates, is substantially parallel to the {001} crystalline orientation plane where {011}. Substantially parallel means here that the deflection after polishing is at most + 5 °.

It is possible to maintain the diamond 1 during cutting for example by cementing or gluing on a temporary support.

The rough face 10 obtained at the end of this cut is then ground and / or polished so as to obtain a polished flat face 11 as illustrated in FIG. 1 C .

The rectification of the face 11 can be performed, as indicated, by means of a laser, for example a laser pulsed between 10 and 100KHz.

The polishing of the face 11 may be performed on a rotary grinding wheel covered with synthetic diamond powder, for example polycrystalline diamond powder.

The roughness of the face 11 can also be reduced by means of a high energy ion beam parallel to the surface.

The diamond is then cut according to a new section parallel to the first section, so as to obtain a thin plate 2 as shown in FIG. 1D. This delicate cut is advantageously performed by laser to avoid shocks that could break the plate. As the cutting of the upper face, this cutting can be performed according to the method illustrated in Figs. 4A-4C, ie by means of one or two laser beams deflected by a mirror to produce a conical ablation zone.

Depending on the type of part desired, this process makes it possible to cut extremely thin plates in a monocrystalline diamond, for example plates with a thickness of less than 400 microns, for example plates with a thickness of between 100 and 400. microns in the case of plates for machining pallets, and plates with a thickness of between 20 and 80 microns, for example 60 microns, in the case of manufacture of anchor wheels or anchors.

This feature allows to manufacture extremely lightweight parts and thus reduce the energy required to put them in motion.

The lower face 12 of the plate 2 is relatively crude. For many applications, especially in watchmaking, this aspect not perfectly polished is entirely satisfactory since this face is not visible. However, it is conceivable by making a slightly thicker piece to also polish this face 12, for example by mechanical polishing on a grinding wheel and / or laser. In one embodiment, the part is held without glue during polishing, preferably by vacuum. It is thus possible to very precisely control the thickness of the piece after polishing, without this thickness depending on the thickness of the glue.

The plate 2 produced can be visually inspected to eliminate the plates which have too many impurities or non-monocrystalline structure. In one embodiment, this control is performed by illuminating the plate with a polarized light that highlights the imperfections. The control can be manual or done by means of a camera and an image analysis software.

During the step illustrated in FIG. 1E, the piece 3 is cut in the surface of the plate 2. This cut is for example obtained by means of a laser beam perpendicular to one of the surfaces 11, 12 or the median plane of the plate 2. In the example of figs. 1E and 2, the piece 3 thus cut is an escapement anchor for watch movement. It is also possible to make other micromechanical parts using the method described above, for example an anchor wheel or a spiral spring or another wheel. Several different pieces can be cut into a single plate.

FIG. 5 illustrates an example of possible trajectory of the laser beam 6 during the machining of a pallet in a plate 11. The laser beam may have a relatively large size, for example a maximum diameter of the order of 20 microns. The shape of this beam 6 is generally non-circular, for example elliptical. The cutting trajectory is therefore advantageously determined by software designed to determine a trajectory of the light beam which takes into account the size, shape and orientation of this beam with respect to the piece to be cut, so as to obtain a piece after release whose dimensions correspond to the desired dimensions.

The trajectory is preferably initiated at a distance from the part to be produced, on a portion 32 that does not belong to the part produced. This avoids the deformations due to the initial drilling. The trajectory is further preferably optimized, taking into account the crystalline orientation of the diamond, so that any cracks that propagate from the point of ablation have a maximum chance of following the edge of the piece, or move away from this room. For example, in fig. 5, the maximum risk of cracking occurs from the initial piercing point 32; the position of this point is therefore preferably chosen so that the most likely crack direction exactly follows the line followed by the beam.

As indicated above, the workpiece is oriented on the diamond plate 11 so that the active surface of the workpiece is in the {111} crystal plane. In the illustrated case of a pallet, the active surface 31 is that which is intended to be brought into contact with the anchor wheel. The pallet is thus cut in the plate 11 so that this surface 31 is precisely in the {111} plane.

The elements 33 in FIG. 5 are cutting indicators used during the subsequent polishing step to define the ideal polishing depth. The polishing will be done precisely until the moment when these marks disappear completely.

Other plates similar to the plate 2 can then be cut in the same diamond 1, in order to make other pieces identical to or different from the piece 3.

In one embodiment, facets are obtained by cutting and / or polishing in one of the upper and / or lower faces 11 or 12, so as to control the direction in which the light passes through the workpiece 3 and the reflections or iridescence produced on the different faces. The room remains however essentially flat; in a preferred embodiment, the ratio between the thickness and the smallest length is greater than 10, advantageously greater than 50, for example greater than 100.

It is also possible to cut into the room 3 a logo, an inscription or a pattern using the laser. This cutout can be through or blind; it allows for example to offer protection against counterfeiting by making copying extremely difficult.

The cutting method in a plate 2 of the part 3 by means of a laser has the disadvantage of producing lateral flanks 13 not perpendicular to the faces 11, 12, as shown in an exaggerated manner in FIG. 3A. The diamond being more or less transparent, the cut is in fact obtained by the attack of the plasma produced by the interaction between the laser light and the air. This results in non-perpendicular flanks and not very smooth. This surface quality is generally not problematic for parts 3 or portions of parts 3 which are not intended to come into contact with other parts. In some cases, however, these irregular surfaces are undesirable either for aesthetic reasons, or because it is necessary to accurately control the shape of the workpiece and the amount of material, for example in the case of a spiral spring. In the case of a part or part portion intended to come into contact with other components of the movement, it is therefore desirable to control the profile and the surface condition of the flanks 13. These requirements are particularly important if the piece 3 is an anchor pallet, a pallet anchor portion, or a tooth of an anchor wheel or other wheel.

In such a case, an optional operation of rectification of the flanks 13, or at least a portion of these flanks, can be performed by means of a laser or a grinding wheel to obtain flanks 14 more. smooth and perpendicular to the surfaces 11, 12, as illustrated in FIG. 3B. In the case of a pallet, at least the active surface 31 can be ground to the depth of the mark 33 by means of a grinding wheel coated with polycrystalline diamond powder. In the case of an anchor wheel, the portion of each tooth intended to be brought into contact with the pallet may be polished or ground by means of a laser beam.

The surfaces of the piece 3 thus obtained are preferably not coated; the monocrystalline diamond has a surface state that is practically ideal both from an aesthetic point of view and with regard to the coefficient of friction or the impact resistance, for example. However, the surfaces 11, 12, 13 or 14 may be covered with traces of graphitized carbon resulting from the destruction of the diamond structure during cutting or polishing operations. In order to eliminate these traces, it is possible in the context of the invention to subject the part 3 to a heat treatment, for example by leaving it for a few seconds or a few minutes in a furnace between 600 ° and 750 ° C., preferably between 650 and 680 ° C; this operation makes it possible to burn the residual graphite at the surface without affecting the carbon in the form of a diamond, and thus to improve the surface state of the part. It also polishes the piece by burning points on the surface.

The piece produced can also be polished by means of an ion beam ("ion etching"), for example an ion beam parallel to the surface to be polished. In one embodiment, this ionic polishing is performed after polishing by heat treatment.

The piece produced can also be polished by means of ultrasound. It can be cleaned with gasoline to improve the appearance of the diamond.

[0108] A mechanical watch movement within the scope of the invention may comprise one or more pieces 3 of monocrystalline diamond. It is possible to choose the hardness of each piece 3 by selecting the type and color of diamond. For example, a part for which maximum hardness is required may be made of synthetic diamond, for example boron doped black synthetic diamond. A part for which such a high hardness is not desired can be made of transparent synthetic diamond, natural diamond, etc. Different diamond pieces of different colors and types can be combined in one movement. For example, it is advantageous to make a pallet or an anchor made of very hard monocrystalline diamond, and a monocrystalline diamond anchor wheel slightly less hard in order to cushion the shocks.

Claims (37)

1. Mechanical piece (3) functional diamond watch movement, characterized in that it is made integrally monocrystalline diamond. 2. Part according to claim 1, consisting of a flat part. 3. Part according to claim 2, comprising a lower face (12) and an upper face (11) parallel to each other. 4. Part according to claim 2, wherein facets are cut on an upper face (11) and / or lower (12). 5. Part according to one of claims 3 to 4, comprising a pattern or a laser-cut inscription in one of said faces. 6. Part according to one of claims 2 to 5, characterized in that it is produced by cutting a plate (2) of monocrystalline diamond. 7. Part according to one of claims 1 to 6, characterized in that the thickness of the plate (2) is between 300 and 500 microns, and in that the part consists of an anchor pallet, the pulse surface of said pallet being cut in the edge of said plate. 8. Part according to claim 7, said impulse surface being substantially parallel to the {001} or {011} crystalline plane. 9. Part according to one of claims 1 to 6, characterized in that the thickness of the plate (2) is less than 120 microns, preferably less than 100 microns, for example between 20 and 60 microns. 10. Part according to claim 9, consisting of an anchor, an anchor wheel, or a spiral spring. 11. Part according to claim 10, said part being flat with an upper surface and a lower surface substantially parallel to the {001} or {011} crystalline plane. 12. Mechanical part according to one of claims 1 to 11, the diamond being natural. 13. Mechanical part according to one of claims 1 to 11, the diamond being synthetic. 14. Mechanical part according to one of claims 1 to 13, the diamond being doped. 15. Mechanical part according to claim 14, the diamond comprising at most 3% doping impurities, without affecting its monocrystalline structure. 16. Mechanical part according to one of claims 14 or 15, the doping being homogeneous in the mass of the workpiece. 17. Mechanical part according to one of claims 14 or 15, the doping being different in surface than in the depth of the part. 18. Mechanical part according to one of claims 1 to 17, the diamond being a black diamond doped with boron. 19. Watchmaking movement comprising at least one piece according to one of claims 1 to 18. 20. The movement according to claim 19, comprising a boron-doped black monocrystalline diamond anchor or pallet. 21. The movement according to one of claims 19 or 20, comprising an anchor or an anchor pallet in a first type of monocrystalline diamond and an anchor wheel in a second type of monocrystalline diamond softer than said first type. 22. The movement according to one of claims 18 to 20, comprising several pieces of monocrystalline diamond of different hardnesses. 23. A method of manufacturing a mechanical part (3) functional diamond, for example a piece according to one of claims 1 to 18, comprising the steps of: cutting a monocrystalline diamond (1) in a first plane (10); cutting the monocrystalline diamond (1) in a second plane parallel to the foreground so as to produce a plate (2) of monocrystalline diamond; by means of a laser, cutting in said plate (2) of said mechanical part. 24. The method of claim 23, wherein the cutting in the first plane is performed by means of a laser. 25. The method of claim 23, wherein the cutting according to said first plane is performed by means of a diamond saw. 26. Method according to one of claims 24 or 25, comprising a polishing step of the first cutting plane (10), so as to obtain a polished surface (11). 27. Method according to one of claims 23 to 26, wherein the cutting in the second plane is performed by means of a laser. 28. The method of claim 27, comprising a step of polishing the second cutting plane (10). 29. Method according to one of claims 23 to 28, comprising a step of polishing a surface by heat treatment at a temperature between 600 ° C and 750 ° C, preferably between 650 ° C and 680 ° C. 30. Method according to one of claims 23 to 29, comprising a step of polishing a surface by ion beams. 31. Method according to one of claims 23 to 30, comprising a step of mechanical polishing of a surface. 32. Method according to one of claims 23 to 32, the diamond being natural. 33. Method according to one of claims 23 to 32, the diamond being synthetic. 34. Method according to one of claims 23 to 33, the diamond being manufactured by carbon deposition by means of a filtered arc or by CVD method on a monocrystalline diamond primer. 35. The method of claim 34, comprising a step of introducing doping impurity during the deposition of carbon. 36. Method according to one of claims 23 to 35, comprising a surface doping step by injection of surface doping ions by means of an ion beam. 37. Method according to one of claims 23 to 36, the diamond being a black diamond doped with boron.