WO2015158631A2

WO2015158631A2 - Method for producing timepieces

Info

Publication number: WO2015158631A2
Application number: PCT/EP2015/057906
Authority: WO
Inventors: Jean-Claude FRÉLY; Ludovic FARRUGGIO; Christophe JOUFFRAY; Xavier LANDREAU; Elmar Mock; Aymeric NIEDERHAUSER; Martin Sigrist
Original assignee: Cartier Création Studio Sa
Priority date: 2014-04-14
Filing date: 2015-04-10
Publication date: 2015-10-22
Also published as: WO2015158631A3; CH711152B1

Abstract

Method for producing a timepiece (2), comprising: providing a mould (1) provided with a precise mould form (10) on an interior surface (11) of the mould, the precise form (10) of the mould corresponding to the negative contours of the timepiece (2) that is to be produced and the mould (1) being made of a mould material (12); spraying a timepiece material into the mould (1); and separating the mould (1) from the timepiece (2); the mould material (12) comprising a salt; the mould temperature (12) being below the temperature at which the salt melts during the spraying step.

Description

Process for producing timepieces

Technical area

The present invention relates to a production process of parts and in particular a production method of timepieces, a production mold of timepieces and a method of manufacturing a mold. The present invention also relates to an apparatus for the production of the timepiece.

State of the art

EP0468467 discloses a method for producing a precision piece of iron or iron alloy, the part being formed of a sintered body obtained by powder molding, said method comprising the steps of forming a homogeneous mixture consisting

essentially iron powder or iron alloy and a binder

organic, shaping the mixture into a molded body of prescribed shape, removing under an inert atmosphere the organic binder of the molded body, reducing said iron powder or iron alloy contained in the molded body to remove the oxygen to form a reduced molded body and to sinter the reduced molded body. In the process described, the molding is made by injection molding and only iron parts are manufactured.

[0003] EP1 172453 discloses a method of manufacturing a final shaped molding tool having a structured mold surface having a uniform surface structure, said method comprising the following steps: a) manufacturing a glass mold or of plastic material having a mold surface for forming the structured surface of the molding tool, b) coating the surface of the glass or plastic mold with at least one material to form a plated body in the glass or plastic mold, c) remove the veneer body having the structured surface of the glass or plastic mold and d) bonding the veneer body to a base body to form the final shaped molding tool with a structured molding surface. The coating of the mold is carried out for example by thermal spraying. The materials used for the plating body are, for example, high-melting metallic or ceramic materials, nickel and chromium alloys, cobalt-based alloys and carbides being included in these materials.

Several processes are known for producing polymer films, for example those disclosed in US200810176034, in which several polymer layers are produced in the form of a film which thus reproduces the surface of a mold with microstructures. Each layer is made of epoxy powder sprayed onto the mold and melted and cured by an infrared or UV source.

[0005] US530141 discloses a method of molding an object by applying segments of complementary material and deposition material so as to form layers of material. The material layers form a block that contains the object made of a deposited material surrounded by a complementary material that serves as a support structure during molding. Then the material

complementary is withdrawn. The additional material is removed by heating the block, whereby the complementary material melts, the deposited material does not melt under the heating conditions. The deposited material and the complementary material are preferably applied by thermal spraying, but they can be applied by welding deposition, from a liquid suspension, by gravity or by any manual means, for example using a manual sieve.

The prior art knows several methods and methods of forming a mold made of a particular material. In addition, methods and methods for coating the surface of a workpiece are also known. These coating processes are used in some conditions of temperature, pressure, etc. The processing conditions depend, for example, on the coating material used.

The post-processing and mechanical finishing of small parts and which must have a precise structure can cause difficulties. These difficulties increase in the case where the part or the surface of the part must meet the demanding requirements in terms of hardness, resistance to abrasion and wear, and tribological characteristics as in the technology of watchmaking. Therefore, there is a need for a method of manufacturing timepieces made of different materials as well as for a corresponding mold and for a method for its manufacture.

summary

In the present text, the term "spray" or the term "projection" is used interchangeably to designate a dry surface treatment technique as defined below. In the same way, the terms sprayed and projected, as well as the terms "spray coat" and "spray coat" are equivalent.

The object of the invention is to provide a method for producing timepieces and a production mold for these timepieces, and a method for manufacturing a mold that makes it possible to manufacture timepieces made of one or different materials.

These objects are achieved with a production method of timepieces and a production mold of timepieces and a method of manufacturing a mold according to the respective independent claims. The production method of a timepiece comprises the steps of: providing a mold having a precise shape of mold on an inner surface of the mold, the precise shape of the mold corresponding to the negative contours of the timepiece to be produced and the mold being made of a mold material,

projecting a workpiece material into the mold; and

separate the mold from the timepiece;

wherein the mold material comprises or consists of a salt;

wherein during the spraying step, the temperature of the mold is kept below the melting temperature of the salt.

In an alternative embodiment, the mold material comprises or consists of a material which has a transition between the solid state at a first pressure (mold material in a first state) to a fluid state at a second pressure pressure (mold material in a second state), the first pressure being lower than the second pressure. This allows the mold material to adopt a second state at the second or higher pressure and to flow around a master shape present in a mold. After releasing the pressure to the first pressure, the mold material resolidifies by adopting a first state. Negative contours of the master form are retained on the inner surface of the mold after removal of the master mold.

In one embodiment, the salt is in particular a

alkali metal halide and in particular potassium bromide, potassium iodide, cesium iodide or a mixture of these salts.

In one embodiment, the temperature of the mold (12) is kept below about 600 ° C.

In one embodiment, the method further comprises the steps of: providing a device for evacuating heat; and put the mold in contact with said device so as to maintain the

mold temperature below the melting temperature of the salt during the spraying step.

In one embodiment, the projection operation and / or the material of the part are modified in a spraying step so that the timepiece comprises a plurality of deposited layers having identical or distinct properties. . At least one of the projection layers may be deposited with variable porosity. The porosity of said one of the projection layers may decrease or increase with increasing thickness of the layer. In a variant, the decrease in porosity can be alternated with

the increase in porosity. The porosity of said one of the projection layers can be up to 30% to 40%. A variable porosity of said one of the projection layers can be obtained by varying the pressure during the projection operation.

In one embodiment, the method also comprises the step of providing a projection device comprising a spray gun through which the material is projected; and wherein a variable porosity of said one of the projection layers is obtained by varying the position of the barrel relative to the mold. A variable porosity of said one of the projection layers is obtained by varying the energy of the projection method.

In one embodiment, the piece material in the mold is a ceramic, a pure carbon material, a metal oxide, a metal, in particular gold, a polymer, a fluorinated polymer, a hard metal material, or a metallic glass.

The invention also relates to an apparatus for the production of a timepiece with the method, comprising:

a mold having a precise mold shape on an inner surface of the mold, the precise shape of the mold corresponding to the contours negative of the timepiece to be produced and the mold being made of a mold material, the mold material comprising a salt;

a projection device for projecting a workpiece material into the mold;

a heat dissipating device configured to be in thermal contact with the mold so that the temperature of the mold remains below the melting temperature of the salt when the workpiece material is projected into the mold.

In one embodiment, the heat dissipating device comprises a device for circulating a cooling fluid. The heat removal device may also include means for controlling the temperature of the mold during the projection of the workpiece material into the mold.

In one embodiment, the apparatus comprises means for storing the mold. The mold storage means may be configured to minimize the water content in the mold material, in particular due to the humidity of the environment. The mold storage means may comprise a hermetic chamber under vacuum, or containing a moisture absorber or a shielding gas, in particular dry nitrogen.

The invention also relates to a production mold of a timepiece, wherein an inner surface of the mold comprises a precise structure which corresponds to a precise shape of the mold and intended to be coated by a projection operation and to be separated from a projected coating on the inner surface of the mold; wherein the thermal conductivity of the mold material is greater than about 5 W m ^-1 K ^-1 and preferably 10 W m ^-1 K ^-1 .

In one embodiment, the mold material comprises or consists of a salt and comprises a thermally conductive powder dispersed in salt. The salt may be in particular an alkali metal halide and especially potassium bromide, potassium iodide, cesium iodide or a mixture of these salts.

In one embodiment, the thermally conductive powder comprises a metal powder, in particular copper or aluminum, or a conductive carbon powder. The powder

The conductive material can be dispersed in the salt so that it is not near the inner surface of the mold.

In a variant, the mold comprises an insert of thermally conductive material.

In one embodiment, the mold material further comprises a reinforcing fiber.

The result is the manufacture of precisely structured parts whose contour is defined by the precise molding shape of the inner surface of the mold. The accuracy of the operation is related to the fact that the precise shape of molding is accurately reproduced by the material that fills the mold. Therefore, it is desired a moderate adhesion between the mold material and the material of the timepiece. Similarly, the exterior of the timepiece is in close contact with the inner surface of the mold. The precise form of molding must be maintained during mold filling by means of a spraying operation. Thus, a feature of the mold material is on the one hand its thermal resistance vis-à-vis the conditions that prevail during the spraying of the workpiece material. On the other hand, the mold material must be able to be separated from the timepiece without damaging the precise structure of the timepiece.

The method is not limited to the production of timepieces and can also be applied to the production of small parts for any use. Any description in the patent application The current mention of timepieces is therefore also applicable to different parts. Typically, these pieces are small and are precisely structured. For example, they have a combination of properties that is achieved by forming the part from the outside towards the inside. The maximum dimensions of the pieces are in the range of 1 mm to 5 cm. The maximum dimensions of the pieces are, for example, a thickness of 0.2 mm to 1 mm to 2 mm and a diameter of 2 mm to 10 mm to 20 mm.

In one embodiment, the spraying step is performed by a thermal spraying operation, the operation being in particular a plasma spraying operation, a chemical vapor deposition operation (CVD, "chemical vapor deposition"). ") or a plasma-enhanced chemical vapor deposition operation (PECVD). This allows to produce a piece of solid material of high purity and high performance. The CVD operation is capable of producing thin layers by chemical reaction and / or decomposition of a volatile precursor on the mold. Different CVD operations are distinguished by the chemical reaction and the treatment conditions used. In addition, more uniform layers can be produced by modifying the treatment conditions towards a lower pressure (LPCVD) or a lower temperature (PECVD).

In one embodiment, the sputtering step is performed by a physical vapor deposition (PVD) operation, for example by cathodic sputtering or by evaporation.

In one embodiment, the projection operation comprises the use of a cold projection method.

The spraying operations used to produce the first part and the second part of the timepiece. We uses a spraying device with certain parameters that are adjustable. After spraying the first part on the inner surface of the mold, a defined set of parameters is changed and the second part is sprayed. The modified set of parameters may for example include the temperature or the nature of the sprayed material (gaseous, liquid or solid state). This modification of the parameters can be carried out gradually or suddenly. Whatever the method, the modification of the parameters gives rise to a modification of the properties of the material. In the present specification, the material of which the timepiece is made is called the material of the part. In the absence of other indications, the term "material of the part" designates the pulverized material as well as the deposited material, in particular the first sprayed layer and the second sprayed layer, as well as the material of a "raw" part, a sintered material or a material that does not yet have the desired final properties for the timepiece 2.

In one embodiment, at least a portion of the material of the part comprises or consists of a ceramic-type material, a pure carbon material, a metal oxide, a metal, a polymer, a fluorinated polymer or a hard metal material, in particular a carbide or a nitride, or other materials that can be applied by a spraying operation. In the case of a timepiece, it is advantageous to have an outer layer (which corresponds for example to the first spray layer) stable and resistant to wear and abrasion. A hard material has for example these properties. Because of these

properties, these materials are difficult to treat, especially if it is necessary to machine a precise shape. Therefore, it is advantageous to use the first sprayed layer to ensure on the one hand the desired properties of the material of the surface layer of the timepiece. On the other hand, the desired shape can be reproduced from the precise shape of the inner surface of the mold. In one embodiment, the step of separating the mold and the timepiece is based on a chemical process and in particular, it comprises the dissolution of mold material by a solvent, a chemical reaction which decomposes the mold material, the melting or burning of the mold materials and / or an electrochemical operation, in particular a galvanic operation. This makes it possible to remove the mold in a particularly gentle manner, in particular when the precise shape of the mold comprises an element of undercut structure. Moreover, this requires the timepiece to withstand the conditions of a chemical separation.

In one embodiment, the separation of the mold and the timepiece is based on a mechanical process, and it includes in particular the percussion or rupture of the mold. This allows the mold to be removed relatively quickly, particularly if the timepiece is hard and not brittle.

In one embodiment, the mold comprises an undercut structure. This makes it possible to produce timepieces that have a wide variety of complex shape structures.

In one embodiment, the mold comprising a precise shape is formed entirely before the spraying step. This makes it possible to apply a homogeneous and continuous sprayed layer on the inner surface of the mold.

The production mold of timepieces comprises an inner mold surface of precise structure. This structure corresponds to the precise shape of the mold and can be coated by a spraying operation. The mold can be separated from the sprayed coating on the inner surface of the mold. This makes it possible to produce a piece

timepiece that has a precise structure, since the precise shape of the mold corresponds to the desired structure for the timepiece. In one embodiment, the inner surface of the mold withstands the conditions that prevail during the spraying operation, the operation being in particular a plasma spraying method, a chemical vapor deposition process or a method of chemical vapor deposition reinforced with plasma. This makes it possible to use a wide range of materials suitable for being sprayed in a spraying operation.

In one embodiment, the material used for the

spraying on the inner surface of the mold comprises or consists of a ceramic material, a metal oxide, a pure carbon material, a pure metal, a hard metal material, in particular a carbide or a nitride, or a fluoropolymer. This makes it possible to form the timepiece by selecting and / or combining materials of different properties.

In one embodiment, the timepiece consists of a single material that has uniform properties.

In general, the conditions that prevail during the spraying of the material of the part are tuned to the desired properties for the timepiece in use. In addition, the mold has good resistance to spraying conditions, the mold can be separated from the timepiece without damaging the timepiece.

Brief description of the figures

The subject of the invention will be explained in more detail hereinafter with reference to preferred embodiments which are illustrated in the accompanying drawings which show schematically:

in Figure 1: a master mold, the mold material being formed in a matrix and the mold material maintaining a master form, in Figure 2: a spraying device (intrinsically) known for coating the mold;

in Figure 3: a series of stages of the production process of a timepiece with a precise structure;

Figures 4a and 4b illustrate the heat removal device, according to one embodiment;

Figure 5 shows a sectional view of a molded door, according to one embodiment; and

Figure 6 shows an enclosure configured to receive one or more mold holders, according to one embodiment.

Example (s) of embodiment

FIG. 1 schematically represents a master mold 3 which comprises at least one die 31 and / or a compression plunger 32. The die 31 and / or the compression plunger 32 comprise a master form 30. The shape master 30 defines the precise structure of a timepiece 2 to be manufactured, and in particular at least a part of the shape of the timepiece 2.

The master mold is filled with a mold material 12, the mold material 12 may be a metallic material, in particular copper, or a polymer material, in particular polyoxymethylene (POM) or polyimide (Kapton), or a solid material at a first pressure and becoming fluid at a second pressure, the first pressure being less than the second pressure. This fluid material at the second pressure may in particular be a mineral salt, in particular a

The mold material 12 is compressed in the master mold 3 by a compressive force 33 (arrows) and flows around the master-form 30 of the master mold 3. The mold material 12 wife therefore the negative contours of the master mold 3 and the future timepiece 2. In the fluid state, the mold material is in a second state 14.

During or after the release of the compression force 33, the state of the mold material 12 passes into a first state 13. The first state 13 of the mold material is a solid state. During the resolidification and after this re-solidification of the mold material in the second state 14 into the mold material in the first state 13, the mold material 12 retains the negative contours of the master mold 3.

In a final step, the mold 1 is removed from the master mold 3, for example by mechanical pressure application possibly in combination with thermal effects to exploit the expansion of the material, the master form 30 corresponding to the shape a piece being reproduced in a precise molded form. The precise molded shape is obtained on the inner surface 11 of the mold. At least a portion of the inner surface 1 1 of the mold is defined by the mold material 12 and resists the conditions that prevail during the continuation of the formation of the timepiece 2. It will be understood that the mold 1 can be made of for example, the mold may comprise a plurality of molded shapes 10 so that a plurality of timepieces 2 may be manufactured with a single mold 1.

In one embodiment, the mold material 12 is a solid material at a first pressure which becomes fluid at a second pressure, the first pressure being less than the second pressure.

When the compressive force 33 which compresses the mold material 12 into the master mold 3 is sufficiently high to reach at least the second pressure, the liquefied mold material 12 flows around the master form 30. Next, the compression force 33 is lowered, the mold material 12 becomes solid and retains the negative contours of the master form 30. In an alternative embodiment, the mold material 12 is a metallic material or a polymeric material. The mold 1 can be made using injection molded ceramic (CIM), injection metal molding (MIM) or plastic injection molding (PIM), mold material 12 fluid (mold material in its second state 14) is compressed in a master mold 3 and the part called "flood" is cooled and demolded. Conventionally, such a "raw part" obtained by a CIM, MIM or PIM operation is fragile and receives its resistance in an additional sintering step. For the application as mold 1, which has a precise shape 10 at the inner surface 1 1 of the mold, it suffices that the "green part" can withstand the conditions that prevail during the formation of the timepiece 2. Therefore, in many cases, the sintering step can be omitted, with the consequence that the mold can be easily destroyed after the formation of the timepiece 2.

In an alternative embodiment, the mold 1 has undercuts. An undercut structure of the inner surface 1 1 of the mold can be achieved by using at least two plungers of

The compression plungers 2 can come into close contact with one another and the molding material 12 is forced up on the sides. The undercut structure of the inner surface 11 of the mold can also be obtained with a mold 1 which comprises at least two mold parts. These mold parts can be combined after re-solidification to form the uniform mold. The undercut structure of the inner surface 11 of the mold can be made in various known ways, for example by using a divisible master mold 3 and / or additional moving moldings which can be removed after re-solidification of the mold. mold material 12 without destroying the precise shape of the mold.

FIG. 2 diagrammatically represents a spraying device 4, the device comprising a spraying gun 41. The material sprayed by the spray gun 41 and also called pulverized material 42 corresponds to the material of which the timepiece 2 is made (material of the part). The pulverized material 42 is sprayed into the mold 1 which has the precise shape of the mold.

The spraying device 4 is used in particular for a thermal spraying operation, the thermal spraying operation being able in particular to be a plasma spraying method, a chemical vapor deposition (CVD) method or a method of spraying. plasma enhanced chemical vapor deposition (PECVD). The plasma spraying operation is performed at low pressure and is in particular vacuum plasma spraying (VPS) or low pressure plasma spraying (LPPS). It is advantageous to use CVD processes because the layer applied to a surface is very homogeneous and a wide range of materials can be deposited as a pulverized material 42. Timepiece 2 may have to exhibit a certain combination of properties, for example a high mechanical strength (hardness), a high abrasion resistance, a high wear resistance, a low electrical conductivity as well as a high

thermal conductivity. Some of these properties, for example mechanical strength, can pose enormous problems when making the piece conventionally, especially when the structures are small and precise. These problems can be overcome with the method presented here by using a pulverized material 42 which has the desired properties. This pulverized material 42 may be a metal oxide, in particular a ceramic-type material, a pure metal, a pure carbon material, a hard metal material, in particular a carbide or a nitride, or a fluorinated polymer, in particular Teflon. ®.

To form a timepiece 2, the mold 1 comprising the inner surface 1 1 mold of precise shape must withstand the conditions prevailing during the spraying operation. The temperature can reach, for example from 200 ° C to more than 500 ° C during the spray. This implies that the mold 1 and in particular the inner surface 11 of the mold must have a high heat resistance where the pulverized material 42 must reproduce the precise shape of the mold.

It may be advantageous that the pulverized material 42 has a strong adhesion to the mold material 12, so as to allow an exact reproduction of the precise shape of the mold.

The properties that are expected of a timepiece 2 and given above relate mainly to the properties of the surface of the timepiece 2, and can therefore form a timepiece 2 which comprises at least two parts. A first part will correspond for example to a surface layer or the coating of the timepiece 2 and a second part will correspond to the material that fills the interior of the timepiece 2. Therefore, the timepiece 2 will be formed in reverse order, the surface layer being first sprayed into the precise shape of the mold and the inner material will then be deposited on the surface layer, for example by filling the rest of the mold.

Different properties of the first coating layer 21 and the second coating layer can be controlled or manipulated.

coating 22 by changing the type, consistency, flow rate, deposition rate, etc., of the pulverized material 42 and / or the thickness of the deposited layer. One possibility of controlling the thickness and quality of the deposited layer is to use a single spraying device 4 in different modes of operation. For example, the spraying device 4 can be used by feeding it with a gaseous material so as to form a thin layer, but subsequently using a solid material (for example a powder) introduced into the same spraying device 4 to form a thick layer that will fill the precise shape of the mold. The materials supplied in the gaseous state and in the solid state may be identical or different. The flow of Deposition can be regulated and affect the properties and quality of the deposited layer using a single spraying device 4.

In an alternative embodiment, the mold 1 may have undercuts. In this case, it is advantageous that the spraying device 4 and the mold 1 can move relative to each other, for example in a reversal movement. The overturning of the spraying device 4 and / or the mold 1 ensures that the undercut portions of the mold can be coated with the pulverized material 42 and that the precise shape of the mold can be reproduced. FIG. 3 represents a series of steps of the manufacturing operation of a timepiece 2. In the first place (FIG. 3a), a mold is provided which comprises an inner surface 1 1 of a mold of a precise form of mold. The precise shape of the mold corresponds to the negative contours of the timepiece 2. In a following step (FIG. 3b), a first spray layer 21 is deposited on the inner surface 11 of the mold 21, which corresponds to a coating. The mold material 12 must withstand the conditions that prevail during spraying, because the precise shape of the mold must be retained. The first spraying step comprises a spraying operation, in particular a thermal spraying operation and in particular a plasma spraying operation, a chemical vapor deposition (CVD) operation or a plasma-enhanced chemical vapor deposition (PSCVD) operation. ). Low pressure plasma spraying methods can also be used to form the first spray layer 21. The first spray layer 21 or the coating corresponds to the surface of the future timepiece 2 and must therefore have a high quality and high performance in terms of hardness and resistance to wear and abrasion. In a subsequent step (FIG. 3c), a second spray layer 22 is deposited or, in this case, a charge of

filling, on the first spray layer 21. The requirements imposed on the second spray layer 22 can be

different from those imposed on the first spray layer 21. This makes it possible to give the material of the timepiece 2 complementary properties, for example a more elastic filling load and a harder coating. Similarly, depending on the requirements, it will be possible to use a less expensive material for the filler than for the coating. The present example has two spray layers, but of course one spray layer or more than two spray layers with different properties can be applied.

It is possible to obtain a modification of the properties of the spray layers by adapting the coating conditions, for example the temperature, the deposition rate, the deposited material and / or the pulverized material 42 introduced into the spraying device 4 in the same manner. passing from a gaseous material to a solid material (powder). The composition of the successive spray layers may vary gradually or abruptly. The second spray layer 22 may be formed by filling the mold 1 at least until reaching a level of

filling.

In a subsequent step (Figure 3e), the excess material that may be present at the outer surface of the mold or exceed the level of filling is ground or abraded. The excess material may comprise a portion of the second spray layer 22 but may also include a portion of the first layer of

spraying 21. The grinding or abrasion used to remove the excess material can be carried out at a stage at which the timepiece 2 is still present in the mold 1 and is thus maintained mechanically and stabilized by the mold 1. In a subsequent step (not shown), an additional layer is sprayed on the ground ground or abraded. The pulverized material may be the material of the first spray layer 21, the material of the second spray layer 22 or a different material.

In another step (FIG. 3e), the mold 1 and the timepiece 2 are separated from one another. The separation step comprises a chemical process or a mechanical process for removing the mold. 1. The chemical process comprises in particular the dissolution of the material 12 of the mold by a solvent, a chemical reaction which decomposes the material 12 of the mold, the melting or the combustion of the material 12 of the mold and / or an electrochemical operation, in particular a galvanic operation . The mechanical process comprises in particular the percussion or rupture of the mold 1. The timepiece 2 or at least the outer surface of the timepiece 2 will have to withstand the conditions that prevail during the separation step.

In one embodiment, the production method of the timepiece 2 comprising the steps of:

providing the mold 1 wherein the mold material 12 comprises or consists of a salt;

projecting a workpiece material into the mold 1; and

to separate the mold 1 from the timepiece 2,

wherein the temperature of the mold 12 is lower than the melting temperature of the salt during the spraying step. The mold material 12 may comprise or consist of a salt in the solid state at a first pressure and in a fluid state at a second pressure, greater than the first pressure. In this case, the first pressure is greater than the pressure prevailing during the projection step. The mold material 12 may comprise an alkali metal halide and in particular potassium bromide, iodide of

potassium, cesium iodide or a mixture of these salts.

The production process can be carried out with a production apparatus comprising:

the mold 1 made of mold material 12 comprising a salt; the projection device 4 for projecting a workpiece material into the mold 1; and

a heat dissipating device 101 configured to be in thermal contact with the mold so that the temperature of the mold 1 remains lower than the melting temperature of the salt when the workpiece material is projected into the mold.

FIGS. 4a and 4b illustrate the heat evacuation device 101 comprising means 102 for circulating a cooling fluid, in the form of a coil, and for supplying this fluid to the device. evacuation of heat 101. The fluid circulation means 102 and supply 103 can be integrated in this device 101.

In FIG. 4b, molds 1 are mounted in storage means 104. In the example illustrated, the storage means takes the form of a mold gate 104 in which several molds 1 are arranged, the mold gate 104 contacting the heat dissipating device 101 (Fig. 4b).

FIG. 5 shows a sectional view of the mold carrier 104 comprising a first disk 105 intended to come into contact with the heat-removal device 101. The first disc 105 comprises through cavities 107 arranged to receive the molds 1. These are fixed in the cavities 107, between a thermally conductive pad 109 and a second disk 106. Once fixed, the lower surface 1 10 of the mold 1 bears against a stud 109 intended to come into contact with the heat-removal device 101. The heat stored in the mold 1 during the projection operation can be dissipated to the heat dissipating device 101. It goes without saying that other configurations for the heat removal device 101 are possible.

The second disc 106 has openings 108 so that the molded mold form 10 is accessible to the projection.

The production apparatus may comprise control means (not shown) for the temperature of the mold during the projection of the workpiece material in the mold 1.

Still in an embodiment illustrated in Figure 6, the storage means 104 comprise a housing 1 1 1 preferably hermetic and configured to receive one or more mold holders 104. The enclosure 1 1 1 can transport the molds 1, for example between production steps of the moldings 2, under conditions where the water content in the mold material 12 is minimized. For this purpose, a vacuum may be made in the chamber 1 1 1, or it may contain a moisture absorber (not shown) or a shielding gas,

especially dry nitrogen.

The thermal conductivity of a mold 1 made with an alkali metal halide such as potassium bromide, potassium iodide or cesium iodide may be insufficient to sufficiently evacuate the heat produced during the process. a projection operation. For example, the thermal conductivity of potassium bromide is approximately equal to 5 W m ^-1 K ^-1 , or more particularly about 4.68 W m ^-1 K ^-1 , and the formation of part 2 with a projection method thermal could lead to a local or global melting of the mold 1 during the thermal spraying phase. It therefore appears advantageous to carry out the manufacture of the part 2 in a mold 1 having a higher thermal conductivity allowing greater heat exchange per unit of time. For example, a thermal conductivity value of the mold 1 may be greater than about 5 W m ^-1 K ^-1 , or even greater than about 10 W m ^-1 K ^-1 . In one embodiment, the mold material 12 contains a thermally conductive powder mixed with the salt. In particular, the thermally conductive powder may comprise a metal powder, especially copper or aluminum, a conductive carbon powder or any other powder of a conductive material or a combination of these powders. The mold 1 obtained from this mixture should have a thermal conductivity which is greater than about 5 W m ^-1 K ^-1 or 10 W m ^-1 K ^-1 . The mold material 12 may also include one or more reinforcing fibers.

Preferably, the conductive powder or the mixture of conductive powders, is dispersed in the salt so that it is not close to the inner surface 1 1 of the mold. Indeed, the absence of conductive powder on the inner surface 1 1 of the mold avoids a possible contamination of the part 2 by this powder.

In a variant, the mold 1 comprises an insert of thermally conductive material. The insert may take the form of a plate or a metal film affixed to the lower face 1 of the mold 1 so as to facilitate the conduction of the heat of the mold 1 towards the heat-removal device 101.

During the projection operation, the mold 1 is brought into contact with the heat-removal device 101 so as to

mold temperature 12 is lower than the melting temperature of the salt during the spraying step.

In another embodiment, the modification of the properties of the projection layers comprises the deposition of a plurality of layers having identical or distinct properties. It is possible that at least one of the projection layers 22 is projected with variable porosity. For example, the porosity of at least one of the projection layers 22 may decrease or increase with increasing thickness of the layer 22. The decrease in porosity can be alternated with the increase of the porosity . It is also conceivable to ensure that the porosity of said at least one of the projection layers 22 can reach up to 30% to 40%. Variable porosity of the at least one of the projection layers 22 can be obtained, for example, by varying the pressure during the projection operation. A variable porosity of said at least one of the projection layers 22 can also be obtained by varying the position of the gun 41 relative to the mold 1, or by varying the energy of the projection method.

In yet another embodiment, the piece material in the mold 1 is a ceramic, a pure carbon material, a metal oxide, a metal, especially gold, a polymer, a fluorinated polymer, a material hard metal or a metal glass.

In yet another embodiment, the workpiece material in the mold 1 is porous gold. In another embodiment, the projection operation is a cold spray process.

The cold spraying method is a cold metallization process, in that the metal powders are sprayed at a very high speed by a pressurized gas (up to 50 bar and heated to a temperature of 50.degree.

maximum temperature of 1100 ° C), the impact force ensuring the quality of the deposit. A convergent-divergent nozzle allows expansion of the gas to ambient pressure, causing its acceleration to a supersonic velocity and cooling to a temperature below 100 ° C. The powders, injected into the convergent part of the nozzle, are accelerated at a speed of up to 1200 m / s, allowing a strong adhesion at the point of impact and therefore a coating of very high quality, very weakly oxidized.

The cold spraying process has many advantages over more traditional metallization processes, in particular, a density of the deposit very close to the theoretical density of the material; a deposit having a low porosity and roughness while allowing to deposit thick (several mm).

However, the most interesting advantage of the cold-spraying method here is the fact that the material is sprayed at a low temperature, making it possible to avoid the problem of evacuation of the heat during the projection operation in the salt mold.

Claims

claims

1. A method of producing a timepiece (2), comprising the steps of:

providing a mold (1) having a precise mold shape (10) on an inner surface (1 1) of the mold, the precise shape (10) of the mold corresponding to the negative contours of the timepiece (2) which must be produced and the mold (1) being made of a mold material (12), projecting a piece material into the mold (1); and

separating the mold (1) from the timepiece (2);

wherein the mold material (12) comprises or consists of a salt;

characterized in that

during the projection step, the temperature of the mold (12) is kept below the melting temperature of the salt.

2. Method according to claim 1,

wherein the salt is in the solid state at a first pressure and a fluid state at a second pressure, greater than the first pressure.

3. Method according to claim 2,

wherein the salt is in particular an alkali metal halide and especially potassium bromide, potassium iodide, cesium iodide or a mixture of these salts.

4. Process according to claim 3,

wherein the temperature of the mold (12) is kept below about 600 ° C.

5. Method according to one of claims 1 to 4,

further comprising the steps of: provide a device (101) for heat removal; and placing the mold (1) in contact with said device (101) so as to maintain the temperature of the mold (12) lower than the

melting temperature of the salt during the projection step.

6. Method according to one of claims 1 to 5,

wherein the projection operation comprises the use of a cold spray method.

7. Method according to one of claims 1 to 6,

wherein the projection operation and / or the material of the workpiece are modified in a spraying step such that the timepiece (2) comprises a plurality of deposited layers having identical or different properties.

8. Process according to claim 7,

wherein at least one of the projection layers (22) is deposited with variable porosity.

9. Process according to claim 8,

wherein the porosity of said one of the projection layers (22) decreases or increases with increasing thickness of the layer (22).

10. Process according to claim 9,

wherein the decrease in porosity is alternated with the increase in porosity.

1 1. Method according to one of claims 8 to 10,

wherein the porosity of said one of the projection layers (22) can be up to 30% to 40%.

12. Method according to one of claims 8 to 11, wherein a variable porosity of said one of the projection layers (22) is obtained by varying the pressure during the projection operation.

13. Method according to one of claims 8 to 12,

comprising the step of providing a projection device (4) comprising a projection gun (41) through which the material is projected; and wherein a variable porosity of said one of the projection layers (22) is obtained by varying the position of the barrel (41) relative to the mold (1).

14. Method according to one of claims 8 to 13,

wherein a variable porosity of said one of the projection layers (22) is obtained by varying the energy of the projection method.

5. Process according to one of claims 1 to 14,

wherein the workpiece material in the mold (1) is a ceramic, a pure carbon material, a metal oxide, a metal, especially gold, a polymer, a fluoropolymer, a hard metal material, or a metallic glass .

Apparatus for producing a timepiece (2) with the method according to one of claims 1 to 15, comprising:

a mold (1) having a precise mold shape (10) on an inner surface (1 1) of the mold, the precise shape (10) of the mold

corresponding to the negative contours of the timepiece (2) to be produced and the mold (1) being made of a mold material (12), the mold material comprising a salt; a projection device (4) for projecting a workpiece material into the mold (1);

a heat dissipating device (101) configured to be in thermal contact with the mold so that the temperature of the mold (1) remains below the melting temperature of the salt when the workpiece material is projected into the mold .

17. The apparatus according to claim 16,

wherein the heat dissipating device (101) comprises a circulation device (102) for a cooling fluid.

18. Apparatus according to claim 16 or 17,

further comprising means for controlling the temperature of the mold during the projection of the workpiece material into the mold (1).

19. The apparatus according to one of claims 16 to 18, further comprising storage means (104) of the mold (1).

20. The apparatus according to claim 19,

wherein the storage means (104) of the mold are configured to minimize the water content in the mold material (12), in particular due to the humidity of the environment.

21. Apparatus according to claim 20,

wherein the mold storage means (104) comprises a sealed enclosure (1 1 1) under vacuum, or containing an absorber

moisture or a shielding gas, especially dry nitrogen.

22. Production mold for a timepiece (2), in which an inner surface (1 1) of the mold comprises a precise structure which corresponds to a precise shape (10) of the mold and intended to be coated by an operation projection and to be separated from a projected coating on the inner surface (1 1) of the mold;

characterized in that

the thermal conductivity of the mold material (12) is greater than about 5 W m ^-1 K ^-1 and preferably 10 W m ^-1 K ^-1 .

23. The mold according to claim 22,

wherein the mold material (12) comprises or consists of a salt and comprises a thermally conductive powder dispersed in the salt.

24. The mold according to claim 23,

25. The mold according to claim 23 or 24,

wherein the thermally conductive powder comprises a metal powder, especially copper or aluminum, or a conductive carbon powder.

26. The mold according to one of claims 23 to 25,

wherein the conductive powder is dispersed in the salt so that it is not in proximity to the inner surface (1 1) of the mold (1).

27. The mold according to one of claims 23 to 26,

wherein the mold (1) comprises an insert of thermally conductive material.

28. The mold according to one of claims 23 to 27,

wherein the mold material (12) further comprises a reinforcing fiber.