EP0082119B1 - Watch case body and method to manufacture the same - Google Patents

Abstract

1. A wrist-watch case middle with an unscratchable caseband, characterised in that its caseband (14) is provided with protruding protective elements (16, 17, 18; 32) made of practically unscratchable material and which when viewed in section in a plane that is co-axial or parallel with the axis of the middle (1, 28) and perpendicular to the case-band (14) thereof, have at least approximately the shape of a circular segment slightly in excess of 180 degrees, the mean portion of the segment of each of said elements being engaged over at most 180 degrees and fixed in a correspondingly shaped recess (15, 29) formed in the caseband (14) of the middle (1, 28).

Description

The middle parts of known wristwatch cases, the edge of which is scratch-resistant, according to the preamble of claim 1, bear a cap of scratch-resistant material or are made entirely of such material. In the first case, the cap in question is an expensive and delicate workpiece, because of its shape and the shrinkage that hard materials, in principle sintered, undergo. In addition, fixing this cap to the middle part of the box is not easy, if it is to be removable and nevertheless sufficiently strong to avoid accidental separation. In the second case, the manufacture is even more difficult and costly, because the piece of scratch-resistant material must still have means allowing it to fix a watch movement. Furthermore, such a part, made entirely of hard material, is subject to rupture due to impact. It follows that its manufacturer is exposed to having to replace a significant number of whole boxes, to ensure after-sales service worthy of the name.

The invention aims to avoid these drawbacks, by protecting the edge of the middle of a wristwatch case by means that are just as effective as the known means, but clearly simpler and therefore less costly. A middle part having the features defined by claim 1 is suitably protected, because the protective elements which line the edge thereof protrude from the latter. They thus keep foreign objects away from the body of the middle part, which can even be made of a relatively soft material, very easily machinable and inexpensive. This protective effect is already achieved by using relatively protruding protective elements, as is apparent from the shape of these elements, which is defined in the characteristic of claim 1. Protective elements emerging from two tenths of a millimeter from the body of the middle give satisfactory results, in particular in the case where a sapphire crystal completely covers the upper face of the middle, as described in the documents, CH-85-641 313, WD-A1-82 / 04134, and WO -A1-82 / 04135 and where the exposed parts of the body of the middle part, above and below the protective elements have a height equal to at most half a millimeter. Finally, the surface of the protective elements, which is engaged in a housing of corresponding shape of the body of the middle part, is sufficiently large to ensure satisfactory fixing of these elements.

Provision has already been made to garnish the edge of a watch case middle with elements partially engaged in a groove in the middle (CH-A-312654). The separate manufacture of the decorative elements and their subsequent attachment to a body of the middle, which it was possible to obtain simply by turning, made it possible to produce boxes with different decorations more easily, and therefore more cheaply, than by machining a middle with one-piece decorations. The decorative elements could, in fact, be manufactured entirely by stretching, parting off, stamping, folding and polishing, so that after their welding to the neckline of the middle part, the latter was finished.

To submit these decorative elements to the said operations, they had to be made of a malleable metal, therefore relatively soft. This proposal therefore in no way suggested the idea of using elements made of material hard enough to be scratch-resistant and even less that of protecting the sides of a watch case case by occupying only part of their area and barely protruding.

It has also been planned to attach decorative sapphire plates, therefore resistant to friction, by gluing, on the upper face of watch cases, bracelet links or other pieces of jewelry (DE-A-2 921 597).

This proposal does not however suggest the particular shape of these elements, which is defined by the present claims, with the aim of protecting the edge of the middle parts of wristwatch cases and, incidentally, giving these middle parts a noticeably tall appearance. reduced by creating, in the corundum, a central zone of strong luminosity, by reflection of the incident light.

The method of fixing the protective elements defined by claim 2 is particularly simple and very effective. There are, in fact, adhesives on the market which resist most chemical agents, including hydrofluoric acid. They also provide an adhesion of 3.5 to 4.5 kilograms-force per square millimeter.

The special embodiments defined by claim 3 are particularly advantageous in that the protective elements which they comprise are extremely inexpensive and that their installation is as easy as rapid.

The invention is not limited to the protection of the slice of polygonal shoulders, as is apparent from claim 4. Although the implementation of the protective elements is more laborious than in the embodiments defined by the claim 3, these executions are still very interesting because of the reduced cost of said protective elements.

Preferably, the protective elements of the edge of the middle part will be made as defined in claim 5, because they give this middle part a very attractive appearance, especially if its upper face is completely covered by glass, as described in the three documents mentioned above, because, in this case, it is possible to match the appearance of the edge of the middle with that of the edge of the glass.

In these latter embodiments, it is even possible to further refine the appearance of the edge of the middle using the features defined by claim 6. The reflections in the transparent corundum of the incident light create, in fact, a central zone of high luminosity, which gives the middle an appearance of appreciably reduced height, in especially when the protective elements are in the form of rods.

The middle part according to the invention is advantageously manufactured according to the method defined by claim 7. It is, in fact, easy to manufacture cylindrical or spherical elements of hard material with the desired diameter. As the build is raw when they are glued, the manipulations that this last operation involves are not likely to alter it. The same applies to the subsequent grinding of the protective elements. This operation does not affect the body of the middle. Finally, the termination treatments then applied to the body of the middle part, which usually include a final polishing and a surface treatment, no longer affect the protective elements, which are much harder than the body of the middle part and than the means used. to polish the latter.

It has already been planned to eliminate certain parts of pieces glued onto fine stones by grinding to the flower of the stone, in order to leave only encrustations in it (FR-A-1 393 525).

In this case, grinding removes a relatively soft material - gold - to leave only encrustations of this material in a hard part - stone - and not vice versa, a very hard material - corundum -, glued to a relatively soft support, in brass, for example.

The special process defined by claim 8 produces squares conforming to those defined by claim 6 in a particularly simple manner.

• La Figure 1 est une vue en plan d'une montre-bracelet équipée d'une carrure selon la première forme d'exécution ;
• la Figure 2 est une vue en perspective à échelle agrandie d'une partie coupée à la Fig. 1 ;
• la Figure 3 est une vue en élévation à plus grande échelle de la montre de la Fig. 1 ;
• la Figure 4 est une vue en plan semblable à celle de la Fig.1, qui représente une montre équipée d'une carrure selon la deuxième forme d'exécution ;
• la Figure est une vue en élévation de la montre de la Fig. 4, qui est semblable à celle de la Fig. 3 ;
• la Figure 6 est une coupe médiane de la carrure de la Fig. 5, perpendiculairement à son axe ;
• la Figure 7 illustre une étape du mode de mise en oeuvre du procédé selon l'invention, et
• la Figure 8 illustre une autre étape de ce mode de mise en oeuvre.

The drawing shows schematically and simply by way of example two embodiments of the middle part of the wristwatch case according to the invention and it illustrates an example of implementation of the method according to the invention.

• Figure 1 is a plan view of a wristwatch fitted with a middle part according to the first embodiment;
• FIG. 2 is a perspective view on an enlarged scale of a part cut in FIG. 1;
• FIG. 3 is a view in elevation on a larger scale of the watch of FIG. 1;
• Figure 4 is a plan view similar to that of Fig.1, which shows a watch equipped with a middle part according to the second embodiment;
• Figure is an elevational view of the watch of FIG. 4, which is similar to that of FIG. 3;
• FIG. 6 is a middle section of the middle part of FIG. 5, perpendicular to its axis;
• FIG. 7 illustrates a step in the mode of implementing the method according to the invention, and
• Figure 8 illustrates another step in this mode of implementation.

As in the case of the watch cases described in particular in Swiss patent application No. 4228 / 80-0, the middle part 1 (Fig. 2) of the watch case shown in Figs. 1 to 3 has its upper face 2 entirely covered by the sapphire crystal 3, which is fixed to the middle part 1 by force engagement in the opening 4 of the latter, with the interposition of a cuff 5, a central plate 6 , transparent, also made of sapphire or made of tempered mineral glass, which is glued under the glass 3. The periphery of the latter carries an opaque decorative frame 7, which determines the appearance of the upper face of the watch, in conjunction with the dial 8, visible inside the frame 7.

The glass of the watch shown could naturally also be arranged and fixed to the middle part 1 in one or other of the ways described in Swiss patent applications No. 2858 / 81-8 and 2859 / 81-0.

As shown in FIG. 1, the middle part 1 has a rectangular outline with corners 9 cut at 45 °. The lower part of the short sides 10, 11 of the middle part 1, extending respectively opposite “12 o'clock _” and “6 o'clock”, is hollowed out in the manner well known to those skilled in the art, so as to form horns allowing a strap to be attached to the box of the watch shown. On the long rectilinear sides 12, 13 of the box, extending respectively opposite "3 o'clock and" 9 o'clock •, the edge 14 of the middle 1 has semicylindrical recesses 15, which extend from one end to the other of these flat faces of the edge 14 of the middle part.

In electronic watches, the thickness of the usual movements, produced in large series, is currently of the order of magnitude close to 2 mm, the dimensions of the recesses 15 can be chosen so as not to allow them to remain, above and below them, only parts of the long sides 12, 13 of the edge 14 of the middle part 1, the height of which does not exceed a few tenths of a millimeter. It will also be noted that these recesses 15 can be machined without difficulty, using a shaped cutter.

Rods 16, 17, 18 in transparent monocrystalline corundum are glued into the recesses 15. In section, these rods have the shape of circular segments extending over a little more than 180 °, so as to exit from the recesses 15 and to be presented parts of about two tenths of a millimeter in thickness projecting from the edge 14 of the middle part 1. On a little less than 180 °, the part of the strips 16,17,18, which is glued in the recesses 15, is coated with a thin reflective metallic layer 19. This layer 19 is deposited on the rods 16, 17, 18 by vacuum spraying in a manner well known to those skilled in the art. The adhesion of a layer deposited in this way is remarkable. It is no longer possible to remove it without taking part of the corundum at the same time.

The side of the middle 1 extending opposite "9 am is provided with two rods, 17, 18, to make room, between them, for the crown 20, which is arranged on this side of the box, so that the rod 16, arranged on the other side and visible to wear, is not interrupted. The layer 19 has, in fact, the property of concentrating in a central zone of the rods 16, 17, 18, the rays of an incident light beam, as shown by the arrows a and b (Fig. 2), so that by observing these rods in the light, we see, in the middle of their flat face 21, a “line 22 of very great luminosity compared to the rest of the rods. Oddly enough, this line 22 gives, apparently, first to the middle, but also to the watch itself, the thickness of a watch with case whose middle is about a millimeter thinner.

The chosen location of the crown 20 therefore also has the effect of not interrupting the optical phenomenon mentioned on the side of the edge of the middle turned towards the hand of the watch wearer, which is precisely the one that comes out of the wearer's sleeves. and is therefore the most visible. The described position of the crown 20 is not disadvantageous. On the contrary, in this place, it is less exposed to the risk of being torn off. In a quartz watch, moreover, this crown is only used for setting the time, which is done to the nearest second, by advancing the minute and second hands and stopping them on a specific time, while waiting the corresponding “top •” of the speaking clock. If the watch is equipped with a calendar mechanism, the crown 20 is also used to update the latter, after the months of less than thirty-one days. However, these operations controlled by the crown, which are relatively delicate and must be carried out with great dexterity, are almost never done while keeping the watch on the wrist. When removed, the location of the crown on either of the long sides of the case is clearly irrelevant.

The ends of the strips 16, 17, 18, which are adjacent to the strap fixing horns, are cut at 45 °, so as to be flush with the corners 9 of the box. Furthermore, various metals, such as for example chromium, silver, gold, and certain carbides such, for example, as those of titanium or boron, can be used to form the layers 19. It is thus possible to '' match the appearance of the sticks 16, 17, 18 to the rest of the visible parts of the middle part (platinum, gold, rhodium silver, stainless steel or chrome, nickel-plated, plated) or to the appearance of the frame 7. For the latter purpose, it is also possible to use colored sintered corundum rods. Such rods would then generally be opaque. It would therefore no longer be necessary to deposit a reflective layer on their surface bonded to the middle part. Consequently, the optical effect of the transparent corundum rods, coated with a reflective layer, would no longer occur. On the other hand, the color of these rods could constitute a happy reminder of that of frame 7. If the latter was made of hard metal, such as a titanium carbide, for example, the rods 16, 17, 18 could also be made using the same hard metal.

In order to adequately protect the edge of the middle, in all cases, a virtually scratch-resistant material, that is to say one which does not scratch, when the watch is worn normally, will be chosen for the strips 16, 17, 18. Since the strips 16, 17, 18 protrude from the middle part 1, the parts of the edge of the latter that they reveal are kept away from contact with foreign objects, which could alter the state of area. Given the lack of grip on such objects offered by the rods 16, 17, 18 themselves, they practically do not risk breaking or sagging. It is thus possible to give the edge of the middle of a wristwatch case an extremely neat appearance, which the wearer of the watch will not have the spite of seeing soon deteriorate.

To make the middle part shown in Figs. 1 to 3, cylindrical elements 23 (Fig. 7) are made, plunge rectified without centers and perfectly polished. The length of the elements 23 will somewhat exceed that of the sides of the middle. A number of elements 23 are then placed in the semi-cylindrical cells 24 of a support 25, which are introduced into a vacuum vaporization installation. The exposure of the elements 23 to the vaporization 26, produces on them the layer 19, which extends over a little less than 180 °. As the surface of the elements 23 is perfectly polished, this layer is automatically reflective. It will be noted that the orientation of the elements 23 on the support 25 is indifferent. There is therefore no precaution to take to fill the cells 24 with this support.

The elements 23, filled with the layer 19, can then be glued to the middle part 1 (Fig. 8). In doing so, care should be taken that the metallized part of the elements 23 disappears inside the groove 15 of the middle part. As the metallization extends over an arc of the section of the elements 23, which is a little smaller than 180 °, it is not necessary to use special provisions to orient the elements 23 relative to the middle part 1 so that their metallized part is indeed entirely inside the groove 15. When the adhesive used is fully polymerized, the elements 23 can no longer be separated from the middle part 1 by destroying them.

These elements 23 are then subjected to the action of a grinding wheel 27, which will remove their outer segment up to line c in phantom, located about two-tenths of a millimeter from the edge 14 of the middle 1. The ends of the elements 23, adjacent to the strap attachment, are also ground at this time flush with the corners 9 of the middle.

If, instead of elements 23 in transparent monocrystalline coridon, opaque elements are used, in sintered corundum or in hard metal, the procedure will be the same, with the step illustrated in FIG. 7 being omitted.

The second embodiment (Fig. To 6) is essentially distinguished from the first by the fact that the long sides of the case and therefore also of the middle part are arched. Instead of milling a continuous groove in these arched faces of the edge of the middle part 28, there are formed in these faces rows of hemispherical cells 29, as close as possible to each other and whose diameter is approximately equal to the width of the grooves 15 of the first embodiment.

This middle part is manufactured as described above, with reference to Figs. 7 and 8. However, we start with balls, instead of cylindrical elements 23. After having glued these balls into the cells 29 of the middle part 28 and having removed a part a little less than half by grinding, it is a chain of spherical caps which garnishes the edge of the long sides of the middle part 28.

If the balls used in this embodiment are made of transparent monocrystalline corundum, then coated with a reflective layer, as illustrated in FIG. 7, an optical phenomenon analogous to that which has been described with reference to FIGS. 2 and 3, also occurs in this second embodiment. However, instead of a “line” of high light intensity, a series of dots 30 appears, each of them being in the center of the flat face 31 of the protective elements 32.

As the optical effect in question is much less marked in the case of the protective elements in the form of spherical caps, than in that of the elements in the form of cylindrical segments, the former will be avoided as far as possible. In many cases, a camber such as that shown in Figs. 4 and 6, could be replaced by two or three flat faces, so as to create a polygonal contour middle with rectilinear sides. The parts of the edge of such a middle part, to be filled with protective elements, would then comprise as many elements in the form of cylindrical segments as there are flat faces.

Given the degree of protection conferred on the edge of the middle by the elements described, it is not necessary that it be made of a particularly hard material. To facilitate machining, the body should preferably be made of brass.

Claims (8)

1. A wrist-watch case middle with an unscratch- able caseband, characterised in that its caseband (14) is provided with protruding protective elements (16, 17, 18 ; 32) made of practically un- scratchable material and which when viewed in section in a plane that is co-axial or parallel with the axis of the middle (1, 28) and perpendicular to the case-band (14) thereof, have at least approximately the shape of a circular segment slightly in excess of 180°, the mean portion of the segment of each of said elements being engaged over at most 180° and fixed in a correspondingly shaped recess (15, 29) formed in the caseband (14) of the middle (1, 28).

2. A middle as in claim 1, characterised in that the portion of each of said elements (16, 17, 18 ; 32) that is engaged in a recess (15, 29) in the caseband (14) of the middle (1, 28) is fixed with adhesive to the walls of said recess over its entire area.

3. A middle as in claim 1 or 2, characterised in that its outline is polygonal and that only the sides thereof extending from the horns of one pair to those of the other are provided with unscratch- able elements (16, 17, 18) said elements having the shape of cylindrical segments and being engaged in longitudinal recesses (15) of semicylindrical configuration in each planar face of the caseband (14) of the middle (1).

4. A middle as in claim 1 or 2, characterised in that the sides there-of that extend from one pair of horns to the other are arcuate and in that said elements (32) have the shape of spherical segments somewhat larger than a hemisphere and the central hemisphere of each element is housed in a hemispherical recess (29) in said sides of the middle (28), with said sides presenting a string of protective elements (32) extending over the entire length of said sides.

5. A middle as in any preceding claim, characterised in that said protective elements (16, 17, 18 ; 32) are transparent or coloured, sintered or monocrystalline, corundum.

6. A middle as in claim 5, characterised in that a portion of the surface of the transparent protective elements (16, 17, 18 ; 32) slightly less than that engaged in the recess (15, 29) of the caseband (14) of the middle (1, 28), is coated with a reflecting metallic layer (19).

7. A method of producing the middle of claim 1, characterised by forming cylindrical or spherical elements (23) from a hard material to the required diameter, fixing them with adhesive in semicylindrical or hemispherical recesses (15, 29), respectively in the caseband (14) of a rough, machined, middle (t, 28), grinding the protruding portion of these elements such as only to leave a small part, and then subjecting the middle to finishing operations.

8. A method as in claim 7, characterised in that said elements (23) being formed are made of transparent corundum and, before fixing them with adhesive to the middle (1, 28), a little less than half their area is coated with a reflecting layer (19) by vaporization in vacuo, by depositing them in semicylindrical or hemispherical cavities (24) in a support (25).

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