FR2735881A1 - Method for fabricating watch faces. - Google Patents

Abstract

A first part of the periphery of the watch face(10) has a circumference sensibly following the watch housings interior circumference into with the face is to be mounted and a second part whose periphery has a concave shape. The method is to form a series of watch faces by means of an annular hollow tool having an interior diameter(Di) and an exterior diameter(De). In the method a first face is cut, then the tool is displaced a distance lees than the arithmetical mean of the interior diameter(Di) and the diameter(De) before cutting a second face adjacent to the other.

Description

DIAL FOR A TIME INSTRUMENT, ESPECIALLY FOR A
WRISTWATCH, AND METHOD FOR MANUFACTURING SUCH
DIAL.

The present invention relates to a dial for a time instrument, in particular for a wristwatch, intended to be mounted on a circular plate.

It also relates to a method of manufacturing a dial for a time instrument, in particular a wristwatch comprising a housing arranged to receive said dial.

Practically all watches currently in existence have a dial generally bearing indications which facilitate the reading of the time and / or improve the aesthetics of the watch. The materials in which these dials are made can be chosen in particular from metals, plastics, glass, stone, ceramic or silicon. Some of these materials are hard and fragile and their machining is difficult. The waste rate can then be relatively high.

The dials formed in the materials mentioned above, and in particular those produced in hard and fragile materials, generally have an octagonal shape.

 ns are obtained from a plate of the chosen material. The plate is first cut into strips using an appropriate saw, then each strip is cut into squares. The four corners of the squares are then cut at an angle of 45 "so as to form a substantially regular octagon. Watches receiving this type of dial include a plate provided with four spans defining a square enabling the dial to be received and guided. 'it is placed between the spans, the dial is covered with a ring provided with four fixing lugs offset by 90 "with respect to each other. This ring is oriented in such a way that the legs are offset from the bearing surfaces. These legs are then bent downwards so as to make the plate, the dial and the ring integral.

The assembly is then placed in a suitable watch case.

This embodiment has various drawbacks. I1 requires the manufacture of several parts, in particular the plate and the ring, the machining of which is complex.

This results in a high manufacturing cost and a long assembly time. In addition, the use of a ring decreases the visible surface of the dial, which damages the aesthetics of the watch.

Another drawback appears when the dial serves as a support for a photovoltaic cell. For the ring to maintain this dial effectively, it must cover a large part of it. n follows a loss of the useful surface of the cell and consequently a non-negligible loss of energy.

All these drawbacks are resolved by the dial according to the present invention, which can be mounted quickly without the intermediary of complex holding elements, and by the method of manufacturing this dial which is simple and economical from the point of view of time. manufacturing and which allows a particularly easy and fast automatic assembly.

These aims are achieved by a dial as defined in the preamble and characterized in that it is circular in shape and that its diameter is equal to the diameter of the plate and comprises at least two concave cutouts arranged to cooperate with at least two convex elements. fixing and / or positioning integral with said plate.

According to a preferred embodiment, the dial is made of a hard and fragile material.

According to a first embodiment, the dial has two cutouts arranged at 1800 from one another.

According to a second embodiment, the dial has three cutouts arranged at 1200 from one another.

According to a third embodiment, the dial has four cutouts arranged 90 "from each other.

According to a fourth embodiment, the dial has six cutouts arranged at 60 from each other.

According to an advantageous embodiment, the fixing and / or positioning elements are formed from a single component, a lower zone of each element being formed by a positioning lug and an upper zone of each element comprising a hook. fixation.

According to a preferred embodiment, the cutouts which are not adjacent to each other cooperate with the positioning elements, the other cutouts cooperate with the fixing elements.

These aims are also achieved by a method as defined in the preamble and characterized in that a first part of the periphery of said dial is cut along a curve substantially along the inside periphery of the case, and in that a second is cut part of the periphery of said dial so as to form at least two cutouts whose periphery is different from the internal periphery of said housing.

In a preferred embodiment of the method in which several dials are produced in series in a flat plate by means of a hollow annular tool having an inside diameter Di and an outside diameter From above said inside diameter, the hollow annular tool is moved a distance less than the arithmetic mean of the inside diameter Di and the outside diameter De between the cutting of two adjacent dials.

The present invention and its advantages will appear better in the following description of an exemplary embodiment and with reference to the accompanying drawings in which: - Figure 1 illustrates a plate in which dials are produced according to the present invention, - Figure 2 is a view of a dial according to the present invention, - Figure 3 illustrates a dial according to the present invention, mounted in a watch case, - Figures 4 and 5 are sectional views respectively along lines AA and B
B of Figure 3, and - Figures 6 to 10 illustrate different alternative embodiments of dials according to the present invention.

With reference to FIGS. 1 to 5, the dial 10 is produced from a flat plate 11.

Each dial is cut by means of a hollow annular tool (not shown) having an inside diameter Di and an outside diameter De. The tool is positioned above the flat plate vertically above the first dial. n is lowered until it enters the material of the plate and cuts this dial which is held in place after cutting. The tool is then lifted and moved parallel to an edge 12 of the plate, by a distance D1 less than the arithmetic mean of the internal diameters Di and external De of the annular tool, this average being hereinafter called the mean diameter of the annular tool. The tool is again introduced into the material and thus cuts a second dial. This manipulation is repeated until the tool is completely outside the plate.

 fi is then brought into a position offset from the starting position, by a distance D2 less than the average diameter of the cutting tool, in a direction perpendicular to the edge 12 of the plate. This distance D2 can be equal to or different from the distance D1. A new series of dials is cut by moving the tool parallel to this edge 12. All this is repeated until all the dials are cut. This cutting is continued until the cutting tool is entirely outside the plate, which allows cuts to be made in the dials obtained near the edges of this plate. The dials are held in place until they are all cut out.

Moving the tool with distances D1 and D2 smaller than its average diameter, generates four cutouts 13 in each dial. These cutouts are arranged 90 "from one another and are used for positioning and maintaining the dial, as is explained in more detail with reference to FIGS. 3 to 5.

In these Figures 3 to 5, the dial 10 is placed on a plate 14 having two positioning lugs 15. Each lug is provided with a curvilinear zone 16 arranged to serve as a guide for the dial. The plate 14 also comprises two fixing hooks 17 mounted in an elastic manner.

The setting up of the dial is done by pushing it down while leaning against the curvilinear zones 16 of the positioning lugs 15. The hooks 17 deviate slightly so as to let the dial pass, then place themselves over and keep it in position.

This embodiment allows the production of a larger number of dials on a single plate. According to a concrete embodiment, the plate 11 typically has a square shape with a side of 300 mm. The diameter of the dials is 25.2 mm. The inside diameter of the annular tool is also 25.2 mm and its outside diameter is 27.6 mm. In this embodiment, the tool is moved 26 mm in a direction parallel to the edge 12 of the plate and 26.25 mm in the direction perpendicular to this edge. fi is thus possible to form eleven rows and eleven columns, which corresponds to 121 dials in a plate. Using the methods of the prior art, it is only possible to produce ten rows and ten columns, that is to say 100 dials. The space saving corresponds to approximately 20%, which makes it possible to correspondingly reduce the manufacturing cost.

FIG. 6A illustrates an embodiment of dials 20 according to the present invention, in which the different dials are produced in a strip 21 of material. The dials are held in place until they are all cut out, so that cutting out a dial allows a cutout 22 to be made in the adjacent dial, previously machined.

FIG. 6B illustrates the dial 20 obtained after having been removed from the strip of material. This dial has two cutouts 22 arranged at 1800 from one another.

In the embodiment illustrated in FIGS. 7A and 7B, the dials 30 are cut from a strip 31 of material and include four cutouts 32 separated by 90 ". The cutouts arranged parallel to the longitudinal direction of the strip are made as in the case illustrated by FIG. 1. To make the cuts in the direction perpendicular to the longitudinal direction of the strip, the cutting tool only partially attacks the material of the strip.

With reference to FIGS. 8A and 8B, the dials 40 are produced in a strip 41 of material whose width is less than their diameter. This makes it possible to form two concave cutouts 42 in a longitudinal direction relative to the strip and two rectilinear zones 43 in a perpendicular direction. These two rectilinear zones have the same function as the cutouts 42.

FIGS. 9A and 9B illustrate an embodiment in which each dial 50 has six cutouts 51 offset by 60 ". To allow this to be done, a first series of dials is cut by moving the cutting tool on a line parallel to a edge 52 of the plate. A second series of dials is cut along a second line parallel to the first line, the centers of two adjacent dials in two different lines being spaced apart by a distance D4 less than the average diameter of the cutting tool The centers of each dial are arranged on a regular hexagon whose length of the sides is less than the average diameter of the cutting tool. This type of dial can for example be mounted on a plate comprising three positioning pins arranged at 1200 from each other and three fixing hooks offset by 60 relative to the positioning pins.

In the embodiment illustrated by FIGS. 10A and 10B, each dial 60 has three cutouts 61 spaced 1200 apart. Each dial is surrounded by three other dials whose centers form the vertices of an equilateral triangle, the dimension of the sides of this triangle being less than the average diameter of the cutting tool. In this embodiment, it is possible to use a cutout for positioning the dial and the other two for its maintenance. fi is also possible to use members having a guide zone in their lower part and a holding zone in their upper part, these members thus ensuring two distinct functions.

In all cases, the cut dials must remain in place while the other dials are cut, so that all cutouts can be made. This is generally done by gluing several plates on top of each other so as to form a stack and by cutting cylinders in this stack by means of the annular tool. The cutting is not carried out over the entire height of the stack so that the cylinders remain in position throughout the cutting time.

The arrangement of the pieces on the plate or strip of material allows easier machining and space saving, therefore faster and more important production for each plate or strip.

The present invention is not limited to the embodiment described, but extends to any modification obvious to a person skilled in the art. The dial can be of any material such as plastic or wood, or in particular of a hard and / or fragile material such as glass, mother-of-pearl, stone or silicon. This dial can also constitute a photovoltaic cell or an electroluminescent disc.

 fi is clear that the dial according to the present invention can equip a wristwatch, but it can also be mounted in any other time instrument such as for example an alarm clock, a pendulum or a pendulum.

Finally, although the process has been described using a hollow annular cutting tool, the same result can be obtained by other machining methods such as molding, stamping, stamping, laser cutting, with a water jet or by means of an abrasive jet, drilling and cutting by ultrasound, by plasma process, by circular cutting with diamond or with a wheel or by combining several of these processes. Generally, the method used will be chosen according to the material constituting the dial.

Claims (10)

Claims 1. Dial for a time instrument, in particular for a wristwatch, intended to be mounted on a circular plate, characterized in that it is circular in shape and that its diameter is equal to the diameter of the plate and comprises at least two concave cutouts arranged to cooperate with at least two convex fixing and / or positioning elements integral with said plate. 2. Dial according to claim 1, characterized in that it is made of a hard and fragile material. 3. Dial according to claim 1, characterized in that it comprises two cutouts (22, 42) arranged at 1800 from one another. 4. Dial according to claim 1, characterized in that it comprises three cutouts (61) arranged at 1200 from each other. 5. Dial according to claim 1, characterized in that it comprises four cutouts (13, 32) arranged 90 "from each other. 6. Dial according to claim 1, characterized in that it comprises six cutouts (51) arranged at 60 from each other. 7. Dial according to any one of the preceding claims, characterized in that the fixing and / or positioning elements are formed from a single component, a lower zone of each element being formed from a positioning lug and a upper area of each element with a fixing hook. 8. Dial according to claims 5 or 6, characterized in that the non-adjacent cutouts cooperate with the positioning elements, the other cutouts cooperating with the fixing elements. 9. Method for manufacturing a dial for a time instrument, in particular a wristwatch comprising a housing arranged to receive said dial (10, 20, 30, 40, 50, 60), characterized in that a first part is cut out of the periphery of said dial along a curve substantially along the inner periphery of the housing and in that a second part of the periphery of said dial is cut so as to form at least two cutouts (13, 22, 32, 42, 51, 61) whose periphery is different from the internal periphery of said housing. 10. The method of claim 9, wherein several dials are produced in series in a flat plate by means of a hollow annular tool having an inside diameter (Di) and an outside diameter (De) greater than said inside diameter, characterized in that between the cutting of two adjacent dials (10, 20, 30, 40, 50, 60), the hollow annular tool is displaced by a distance (dol, D2, D4) less than the arithmetic mean of the internal diameter ( Di) and the outside diameter (De).