EP0216223B1 - Combined watch middle and movement plate, manufacturing process of the same and watch provided with such a combined watch middle and movement plate - Google Patents

Description

The main object of the present invention is a base plate for a watch, made of brass; this middle plate includes lower and upper faces, at least one being provided with recesses intended to receive components of a watch movement, as well as lateral faces. It is also provided with a coating made of a chemically more inert material than brass which covers at least the side faces.

Watches with middle plates have been described in numerous patents, such as Swiss patents 296, 6502 and 250,700, or in French patent application 2,085,292. However, to date, the number of practical achievements has been extremely reduced, if not zero.

Furthermore, brass is very frequently used in watchmaking, in particular for the production of watch plates and cases. This material has the advantage of being easy to machine. On the other hand, it is very subject to oxidation.

To remedy this drawback, the plates are generally coated with a layer of nickel, itself covered or not with gold. Their total thickness generally does not exceed 2 µm. This is enough to protect the brass, while minimizing the dimensions of the plates.

In the manufacture of watch cases, brass is coated with a layer of chrome, gold, or any other protective material. The protective layer of the box must be much more resistant than that of the plates, because it is subjected to numerous physical and chemical attacks. Consequently, a layer of 2 J.1.m is not sufficient. In practice, the thickness is generally at least 5 µm and can exceed 20 wm. Such thicknesses deposited on the plate would considerably increase the dispersion of the size value, thus making the plates unsuitable for automated assembly of the components.

Thus, to make a watch with a brass middle plate, we are faced with the dilemma of having effective protection, in which case the brass must be coated with a thick protective layer, which makes assembly difficult, or to have a sufficiently thin layer so as not to disturb the assembly, the exterior of the watch can then be very quickly altered.

The Swiss patents 296 and 6,502 ignore this problem.

Swiss patent 250,700 envisages this and proposes to produce the platinum part in brass and the middle part in steel, these two parts being assembled by welding or forcing. If at first glance this way of doing things seems attractive, we also understand that the enormous tensions that it can generate risk deforming the platinum part of the mantle to make it unsuitable for automated assembly.

French patent application 2,085,292 proposes aluminum, copper, metal alloys and synthetic materials as the material which can be used for the production of a base plate, without considering the deposition of a protective layer. None of these materials seems to allow machining of the platinum part sufficiently precise to allow automated assembly, except for an alloy such as brass which, because of its sensitivity to oxidation, must include a protective coating.

US-A-360 477 describes a watch provided with a platinum build, a crystal and a case back. The middle plate is for example brass. It has lateral faces forming the edge of the middle part and therefore exposed to chemical and physical attack when worn. To protect these lateral faces, it is proposed to coat them either with a gold or silver ring, welded to the brass, or with a layer of metal deposited for electro-deposition. In this case, the platinum part is not protected at all.

An object of the present invention is to produce a middle plate as described above, but the middle part of which offers good resistance to chemical and physical attack, without however assembling the movement components. of the watch is complicated. This object is achieved thanks to the fact that the middle plate has the characteristics set out in claim 1.

Thanks to this particular configuration, it is possible to produce a middle plate, in which the plate part can be manufactured without problem with sufficient precision, while having a particularly resistant middle, both to chemical and physical attack.

The present invention also relates to a method for manufacturing square plates.

In the known methods of depositing a protective layer, a large part of the cost is due to the machines they require, by the space they occupy and by the handling.

Another object of the present invention is to reduce these costs.

This object is achieved by the process defined by claim 13.

Furthermore, in known manufacturing methods, the shoulders and more particularly their exposed surfaces are machined piece by piece, which also increases the manufacturing cost. On the other hand, when the periphery of the base plates is machined after the protective layer covering the recesses has been laid, the chips and the machining lubricants risk altering the surface condition of this layer.

Another object of the present invention is to reduce the manufacturing cost while allowing machining after deposition of this layer, without risk of alteration.

This object is achieved by the process defined by claim 13.

The present invention also relates to a watch provided with a middle plate according to one of claims 1 to 12. As has been said above, the industrial manufacture of watches provided with a middle plate has so far been impossible because Difficulties in achieving a satisfactory compromise, both the dimensional constraints specific to automated assembly and the requirements relating to the resistance to attack to which a watch is subject differ.

Another object of the present invention is to solve this problem.

This object is achieved thanks to the characters specific to the watch which is the subject of claim 17.

• - la figure 1 représente, en plan, avec arrachement partiel, une montre munie d'une platine carrure selon un premier mode de réalisation de l'invention;
• - la figure 2 est une vue en coupe suivant la ligne II-II de la montre de la figure 1;
• - la figure 3 représente, de manière agrandie, une partie de la vue en coupe de la figure 2;
• - les figures 4 et 5 montrent, en coupe, la périphérie de deux autres modes de réalisation de montres selon l'invention; et
• - les figures 6 et 7 illustrent des empilements de platines carrures en cours de fabrication.

The invention will be better understood on reading the description which follows, made with reference to the drawings in which:

• - Figure 1 shows, in plan, with partial cutaway, a watch provided with a middle plate according to a first embodiment of the invention;
• - Figure 2 is a sectional view along line II-II of the watch of Figure 1;
• - Figure 3 shows, in an enlarged manner, part of the sectional view of Figure 2;
• - Figures 4 and 5 show, in section, the periphery of two other embodiments of watches according to the invention; and
• - Figures 6 and 7 illustrate stacks of middle plates during manufacture.

In these drawings, the same elements have the same references. In addition, the thickness of the protective coatings has been exaggerated in order to facilitate understanding.

The watch shown in FIGS. 1 to 3 comprises a middle plate 10 carrying different components of the watch movement, a crystal 12 and a base 14 which protect these components, as well as a bracelet 16.

More specifically, the middle plate 10 comprises a first part 18 forming the middle part, of annular shape, and a second part 20, surrounded by the part 18 and forming the plate.

The part 18 forming the middle part comprises an upper face 22, a lower face 24 on which the glass 12 and the base 14 respectively bear, and lateral faces 26.

The face 22 has a peripheral groove 28 in which is housed a seal 30 which seals between the middle plate 10 and the crystal 12. The face 24 has a peripheral groove 32 in which is housed a seal 34 which seals between the middle plate 10 and the base 14.

The lateral faces 26 comprise, in opposite positions, two ears 36 each provided with a support surface 38 and a groove 40. The support surfaces 38 are parallel to the faces 22 and 24. They act as support to claws 42 intended to fix the glass 12, by pressing a spout 42a which cooperates with a bevel 12a of the glass 12 (Fig. 2). The claws 42 are made integral with the holes 36 by screws 44 each engaged in a cylindrical hole 46 which the ears 36 have and clamped in tapped holes 48 which are each provided with the claws 42.

A bar 50, serving as attachment to the bracelet 16, is engaged in each of the grooves 40 and held by the claw 42.

The part 20 forming a platinum, includes recesses 52, which define clearances, in which various components of your watch are housed. Among these components, the display means formed by needles 54 can be noted, as well as the parts constituting the drive, control and correction means of the display means, shown diagrammatically at 58.

If, for some of these grooves, the accuracy can be relatively low, for others, such as the groove 52a (Fig. 3), which has a hole 52b, the precision required is much greater. This is due to the fact that the hole 52b, which takes the place of pivoting to a mobile 58a, must have a perfectly defined diameter and position to guarantee a good meshing of the various mobiles of the watch.

Also, to make a brass plate in which even the tightest tolerances are respected, and whose surface is protected, the latter is covered by means of a layer 60 of a noble or passivable material, such as for or the nickel, whose thickness is between 0.5 and 3 µm, typically 2 µm.

This protective layer 60 is more than sufficient to maintain the appearance of the part 20, which is protected from external attack by the glass 12 and the bottom 14. On the other hand, it is not at all suitable for protecting the lateral faces 26 , which are subjected to physical aggressions such as abrasion or shocks and to chemical aggressions, for example by sweat. To solve this problem, the lateral faces 26, as well as the parts of the lower face 24 not covered by the bottom, are coated with a layer 62 of a material chemically more inert than brass and more resistant to chemical and physical attack. than layer 60. This material can be chromium, gold, titanium, aluminum or carbide or nitride of a metal chosen from titanium, vanadium, tungsten, or even a layer of organic material such as paint or rubber. When the layer 62 is made of one of these metals or metallic compounds, its thickness is advantageously between 5 μm and 30 μm, typically 10 μm. It gives exposed areas a resistance far greater than that which can be expected from a brass part, even protected by means of the layer 60 of nickel or gold, as is the case with the platinum part.

When the layer is made of gold, its thickness generally exceeds 8 µm to be able to benefit from the designation "gold plated".

When the layer is made of galvanically deposited aluminum, it has a thickness of taken between 20 and 30 pm. This layer is then oxidized, also galvanically, to harden and color it.

The deposition of the aluminum layer can be carried out according to the method described by U. Landau: report of the conference "INTERFINISH EUROPE" Berlin 1985, pages 317 to 324.

When the layer 62 is made of rubber, its thickness is advantageously between 0.5 and 1 mm. In this case, the seals 30 and 34 can advantageously be molded in one piece with the protective layer 62.

It is also possible to produce layer 62 by means of paint, generally enamel paint, advantageously deposited by electrophoresis.

In the variant shown in Figure 4, the middle portion 18 of the middle plate 10 projects beyond the glass 12 and the bottom 14, and has peripheral bevels. In this embodiment, the part 18 of the middle projecting from the bottom 14 and the crystal 12 is entirely covered with the protective layer 62, represented by a thick line. As will be seen below, the glass and the bottom are advantageously aligned vertically with respect to each other.

In the variant shown in FIG. 5, it can also be seen that the part 18 projecting from the glass 12 and the bottom 14 is entirely covered by the protective layer 62. In this embodiment, the lateral face 26 is connected to the faces upper 22 and lower 24 by rounded 63.

The forms that part 18 can take are very numerous. For each, however, the brass must be provided with the protective layer 62 in the parts not covered. It goes without saying that this layer may overflow onto the parts covered by the bottom or the glass for example; but it is necessary that the surfaces of the recesses 52 are free of it for the reasons mentioned above.

The manufacture of turntables such as those shown in Figures 1 to 5 is done starting from a brass band in which are cut plates, any shape, preferably round or rectangular and whose dimensions are greater than those of the turntables completed. These plates are thick and machined so as to produce the clearances 52 intended to receive the components and holes such as the working holes making it possible to position the plate during the manufacturing operations or the holes intended to form the bearings of the mobiles. .

The machining of the plate forming part 20 having been completed, as well as that of the upper 22 and lower 24 faces, the middle plates are then cleaned and coated, generally by galvanic means, with the protective layer 60. The part 20 and the faces 22 and 24 thus have their final surface state. Against by the side faces 26 are still in the rough. They must be machined to define the periphery of the part forming the middle part 18 and to make means for fixing the bracelet. These operations differ significantly from those during which the platinum part is machined. If the required precision is less, the surface condition on the other hand must be without imperfection. In addition, the shape must be easily changed from one room to another, so as to increase the possibilities of aesthetic creation.

To perform this machining, and to the extent that the side faces 26 are perpendicular. on the lower 24 and upper 22 faces, it is possible to stack the middle plates on a support such as that shown in FIG. 6. This support comprises a base 64, positioning rods 66, only one of which is visible at drawing, an upper plate 68 and screws 70. The base 64 and the plate 68 each further comprise a lug 71, visible only on the plate 68 and intended to fix the stack on the machining machine.

The base 64 and the plate 68 are advantageously made of brass and of dimensions equal to those of the base plates 10 before machining. The middle plates 70 are threaded on the rods 66, each rod having a position corresponding to a working hole that the middle plate comprises. The free end of each rod 66 has a tapped hole intended to receive one of the screws 70.

After the stack of middle plates 10 is stiffened by tightening the screws 70 in the rods 66, the assembly is mounted on the machine tool, a numerically controlled milling machine for example. The periphery is then defined by milling. The surface finish can be refined by brushing, sanding or polishing for example. The stack is then cleaned. After which it is placed in an enclosure allowing the deposition of the coating material by chemical vapor phase, known by the abbreviation CVD or by physical vapor phase known by the abbreviation PVD. It is obvious that a person skilled in the art will take all the necessary precautions to guarantee maximum adhesion of the coating and thus to provide it with good abrasion resistance. This maximum adhesion can, in certain cases, be obtained by depositing successive layers. For example, it is common to deposit an underlying layer of nickel.

As a variant and when the layer covering the middle part is made of gold, aluminum or chromium for example, it can be deposited galvanically, the middle plates 10 being stacked in the same manner as that just described.

This procedure allows the external shape of the parts forming the middle part to be machined and the protective coating to be deposited on a large number of parts at the same time, the adjacent faces of two neighboring plates being mutually masked, while the external faces of the plates. ends are covered by the base 64 and the plate 68.

It is quite obvious that if one wishes to have a more elaborate external shape of the middle, such as those represented in FIGS. 4 and 5, it is necessary to machine each middle plate one after the other. During this operation, shavings are projected onto the platinum part, which risks damaging the layer 60. It is therefore preferable to complete the machining operations before the deposition of this layer 60. In this way, the lateral faces 26 are also covered. Depending on the material used to make the layer 62, it may be appropriate to remove, for example by chemical attack, the layer 60, to improve the bonding of the layer 62. This operation is carried out after stacking the middle plates. In this way, the platinum part is spared.

In the case where the upper 22 and lower 24 faces must also be partially covered in their periphery by the layer 62, the middle plates 10 are no longer simply stacked one directly above the other, but spacers 72 are interposed between them as can be seen in FIG. 7. These spacers cover the zones which, after assembly of the watch, are protected by the crystal 12 and the bottom 14. As we said previously, if the bottom 14 is aligned with the glass 12, it suffices to make spacers 72 having a surface identical to that of the glass and the bottom.

In the case where the surface covered by the ice is greater or less than that covered by the bottom, one could make two kinds of spacers 72, one of which has an area identical to that of the ice and the other to that the bottom. In this case, it would suffice to place the turntables 10 upper face against upper face and lower face against lower face, by inserting a spacer having the same surface as the glass, respectively as the bottom.

The thickness of the spacer 72 is chosen to be as small as possible, but sufficient however to guarantee a deposit of material up to the bottom of the groove formed by two superimposed plates 10. This result can be obtained when the depth of the groove is substantially equal to the thickness of the spacer.

It goes without saying that the layer 62 can overflow under the bottom 14 or the glass 12, without disturbing the proper functioning of the watch. It suffices for this that this layer 62 does not protrude into the plate forming part 20 of the middle plate 10.

In FIGS. 1 to 5, the crystal is directly fixed to the middle plate 10. It could also be secured to a bezel, this bezel itself being fixed to the middle plate 10.

It should also be noted that because the lower and upper faces of the middle plate 10 are flat, those adjacent to the crystal and the bottom can also be. The cost is therefore minimal.

Furthermore, in an embodiment not shown in the drawing, the lower and upper faces could be of any shape, adapted to receive a bottom and a glass of more complex structure. In this case, the shape of the spacers should be chosen so as to be complementary to the shape of the surfaces with which they collaborate.

As we have just seen, it is thus possible to produce a watch comprising a middle plate in which all the parts forming the frame and the box are adequately protected. It is also possible to achieve a significant reduction in the cost price of the finished watch, without having to make concessions in terms of the quality of the finished product.

Claims (18)

1.Awatch middle cum plate (10) made of brass comprising bottom (24) and top (22) faces with at least one formed with recesses (52) for receiving components (50) of the watch, and side faces (26) and provided with a coating (60, 62) made of a material that is chemically more inert than brass and which protects the latter at least on said faces (26) characterized in that said coating includes two parts, a first part (60) that protects the brass in the regions of the middle cum plate that are formed with said recesses (52) and a second part (62) that protects the brass at least over said side faces (26) and in that the thickness and the resistance to chemical and physical attacks of the second part (62) are better than the ones of the first part (60).

2. A middle cum plate according to claim 1, characterized in that the periphery of at least one of said bottom (24) and top (22) faces is covered by the second part (62) of said coating.

3. A middle cum plate according to one of claims t and 2, characterized in that the first part (60) of said coating consists of a layer of metal selected from the group consisting of gold and nickel

4. A middle cum plate according to claim 3, characterized in that the thickness of said layer ranges from 0.5 to 3 µm.

5. A middle cum plate according to anyone of claims 1 to 4 characterized in that the second part (62) of said coating consists of a layer of metal selected from the group consisting of gold, chromium, titanium and aluminium.

6. A middle cum plate according to claim 5, characterized in that the thickness of the metal layer of coating in its second part (62) exceeds 8 µm.

7. A middle cum plate according to anyone of claims 1 to 4, characterized in that the second part (62) of said coating consists of a layer of carbide or nitride of a metal selected from the group consisting of tungsten, vanadium and titanium.

8. A middle cum plate according to claim 7, characterized in that the thickness of the coating layer in its second part (62) exceeds 5 µm.

9. A middle cum plate according to anyone of claims t to 4, characterized in that the second part (62) of said coating consists of a layer of organic material.

10. A middle cum plate according to claim 9, characterized in that said organic material is an organic paint.

11. A middle cum plate according to claim 9, characterized in that said organic material is rubber-

12. A middle cum plate according to anyone of claims to 11, characterized in that at least one bonding sub-layer is provided between said brass defining the middle cum plate (10) and said coating t60, 62).

13. A method of making watch middles cum plates (10e) according to claim 1, from flat brass blanks, each having bottom (24), top (22) and side (26) faces, wherein the central portion of at least one of said top and bottom faces comprises recesses (52) for receiving components of a watch movement (58), characterized in that the middles cum plates are coated with a layer of metal that is chemically more inert than brass to form a first part (60) of a protective coating, the middles cum plates are stacked and assembled such that at least the central portions with the recesses (52) are masked and in that the visible regions of the middles cum plates are coated with a protective layer forming a second part (62) of said coating.

14. A method according to claim 13, characterized in that the adjacent top and bottom faces of a pair of contiguous middles cum plates mask each other.

15. A method according to claim 14, characterized in that the side faces (26) of the middles cum plates once stacked and assembled are machined collectively to define the outer shape of their middle-forming portions before applying the second part (62) of the coating.

16. A method according to claim 13, characterized in that a spacer (72) is provided between each of the middles cum plates while being stacked, said spacer only partly covering the top and/or bottom adjacent faces.

17. A watch having a middle cum plate according to anyone of claims 1 to 12 a glass (12) and a back (14), characterized in that the first part (60) of the coating is completely covered particularly with the glass (12) or the back (14).

10. A watch according to claim 17, characterized in that the bottom (24) and top (22) faces of the middle cum plate are flat and parallel around their peripheral portion and in that said glass (12) and back (14) have flat parallel faces and overlay said top (22) and bottom (24) faces of the middle cum plate (10).

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