EP2273324A1 - Method for manufacturing a decorated part with raised pattern - Google Patents

Abstract

The method involves partially covering raised patterns (23, 25, 27) with a decorative layer. A body (22) of a part (21) is formed. A surface of the body of the part is selectively structured to locally modify a surface state. The decorative layer is directly deposited on the body. Parts of the deposited decorative layer are removed when the parts of the deposited decorative layer are not adhered to the body of the part. The decorative layer is made of a metallic material. The body of the part is made of plastic.

Description

Field of the invention

The invention relates to a method of manufacturing a decorated relief piece and, more particularly, such a plastic piece whose decorations have a metallic appearance.

Background of the invention

A timepiece dial usually has sconces to decorate it. These appliques may for example represent a time lapse to facilitate the determination of the time relative to the location of the needles of the timepiece. These sconces can also be used to simply bring an aesthetic effect to the dial.

Usually, these sconces are mounted on the dial by successive steps of gluing and possibly masking and / or buffering which, in addition to the price of the sconces, causes additional manufacturing costs due to the positioning accuracy required which is to as much larger than the wall lamp is thick.

Summary of the invention

The object of the present invention is to overcome all or part of the disadvantages mentioned above by more generally proposing a method of manufacturing a decorated part which has fewer steps and consumes less material to make the decorations.

1. a) former le corps de la pièce ;
   caractérisé en ce que le procédé comporte en outre les étapes suivantes :
2. b) structurer sélectivement la surface du corps de la pièce afin d'y modifier localement l'état de surface ;
3. c) déposer sur tout le corps ladite couche de décoration ;
4. d) débarrasser les parties de la couche déposée qui n'ont pas adhérées au corps de la pièce

For this purpose, the invention relates to a method of manufacturing a raised piece, which reliefs are at least partially coated with a decorative layer comprising the following step:

1. a) forming the body of the room;
   characterized in that the method further comprises the following steps:
2. b) selectively structuring the surface of the body of the part to locally modify the surface condition;
3. c) depositing on the whole body said decorative layer;
4. d) rid the parts of the deposited layer that have not adhered to the body of the part

Advantageously according to the invention, it is therefore understood that it is no longer necessary to selectively deposit the decorations. Prior structuring makes it possible to precisely select the zones of adhesion and / or non-adhesion in order to simplify the step of depositing the decor (s).

• l'étape b) est destinée à diminuer localement l'adhérence de la surface du corps afin que, lors de l'étape c), la couche déposée n'adhère pas ou au contraire adhère sur les parties structurées ;
• l'étape a) est réalisée par une injection de matière dans un moule ;
• l'étape b) est réalisée en modifiant localement l'état de surface interne dudit moule ou par rayonnement du type laser ;
• l'étape c) est réalisée par un dépôt physique en phase vapeur ;
• la couche de décoration comporte au moins un matériau métallique ;
• après l'étape d), une galvanoplastie est réalisée afin d'épaissir chaque partie comportant ladite couche de décoration ;
• le corps de la pièce est réalisé à l'aide d'une matière plastique ;
• la pièce en relief est un cadran de pièce d'horlogerie.

According to other advantageous features of the invention:

• step b) is intended to reduce locally the adhesion of the surface of the body so that, in step c), the deposited layer does not adhere or otherwise adheres to the structured parts;
• step a) is performed by injecting material into a mold;
• step b) is carried out by locally modifying the internal surface state of said mold or by laser-type radiation;
• step c) is carried out by a physical vapor deposition;
• the decorative layer comprises at least one metallic material;
• after step d), an electroplating is performed in order to thicken each portion comprising said decorative layer;
• the body of the piece is made using a plastic material;
• the relief piece is a timepiece dial.

Brief description of the drawings

• la figure 1 est un cadran typique de pièce d'horlogerie vu de dessus ;
• la figure 2 est une section schématique selon la coupe A-A de la figure 1 ;
• les figures 3 à 7 sont des représentations d'étapes successives de deux modes de réalisation du procédé de fabrication selon l'invention ;
• la figure 8 est un schéma fonctionnel du procédé de fabrication selon l'invention.

Other particularities and advantages will emerge clearly from the description which is given hereinafter, by way of indication and in no way limitative, with reference to the appended drawings, in which:

• the figure 1 is a typical timepiece dial seen from above;
• the figure 2 is a schematic section according to the AA section of the figure 1 ;
• the Figures 3 to 7 are representations of successive steps of two embodiments of the manufacturing method according to the invention;
• the figure 8 is a block diagram of the manufacturing process according to the invention.

Detailed Description of the Preferred Embodiments

The Figures 1 and 2 represent a typical dial 11 for a timepiece. As explained above, the method 1 according to the invention is not limited to the manufacture of a dial but to any type of plastic part decorated in relief. However, a timepiece dial is a good example of application of the method 1 according to the invention.

As visible to Figures 1 and 2 a dial 11 is typically a multi-level body 12. In the example shown in figure 2 it can be seen that the body 12 includes in particular a circular recess 19 capable of forming a secondary display of the timepiece. It is also noted that the upper face of the body 12 comprises one hour lap in the form of indexes 13 regularly spaced. In the same way, the secondary display comprises a second series of indexes 15 which borders on said circular shape. Finally, the upper face comprises a decoration 17 intended to mask the shoulder between said upper face and the recess 19.

As explained above, to make such a dial 11, it is necessary to report these indexes 13, 15 and decor 17 by successive steps of bonding and possibly masking and / or buffering when the reliefs are very pronounced. Advantageously according to the invention, the manufacturing method 1 makes it possible to provide a new type manufacturing which is particularly suitable for plastic parts 21 whose reliefs are very pronounced, that is to say greater than 40 microns.

As illustrated in figure 8 , the manufacturing method 1 comprises a first step 3 for manufacturing the main body 22 of the future plastic part 21 (a dial 21 in the example below). Preferably, step 3 is performed by injecting said plastic into a mold (not shown). Indeed, this type of manufacture allows the precise roughing of the raised portions of the dial 21.

In the example shown in figure 3 , it is possible to distinguish in particular the raised locations 24, 26 and 28 intended to form respectively the future indexes 23, 25 and decor 27. There is also the hollow part 29 intended to form the secondary display. It is therefore understood that in a single step 3, the positions of the different parts of the dial 21 are made very precisely. According to the invention, the plastic material for producing the body 22 may be, for example, thermoplastic resins such as styrene such as acrylonitrile-butadiene-styrene (ABS), acrylic resins such as polymethylmethacrylate (PMMA) and mixtures such as PMMA / ABS, polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamides, polycarbonates (PC), ABS / PC mixtures, an ethylene-vinyl acetate copolymer ( EVA), polyimides or fluorinated resins such as polytetrafluoroethylene (PTFE).

In a second step 5 of the method 1, the surface of the body 22 is structured to locally modify its surface state. According to the invention, step 5 comprises two embodiments according to the adhesion characteristics of the plastic material used. Indeed according to the invention, the decorative layer will be applied directly to the body 22 of plastic.

Thus, in a first embodiment in which the plastic material has a very low adhesion with respect to the decorative layer to be deposited, step 5, as illustrated in FIG. figure 4 , is intended to locally increase the adhesion of the surface of the body 22 to the parts to be decorated, that is to say the elevations 24, 26 and 28.

Conversely, in a second embodiment in which the plastic material has good adhesion with respect to the decorative layer to be deposited, step 5, as illustrated in FIG. figure 5 , is intended to reduce locally the adhesion of the surface of the body 22 at the level of the parts that are not to be decorated, that is to say all parts except the elevations 24, 26 and 28.

Step 5 to selectively structure the surface condition of the body 22 may be destructively or non-destructively contemplated. Indeed, according to a non-destructive alternative, it can be envisaged that the surface condition is "manufactured" at the same time as the body 22 itself, adapting "in negative" the internal surface of the mold used during the step 3. It is then clear that steps 3 and 5 would then be performed at the same time.

However, step 5 for selectively structuring the surface state of the body 22 may also be performed in another alternative in a destructive manner, i.e., by removal of material. Preferably, in this alternative, the structuring of step 5 is performed by laser-type radiation which offers a very high precision for a modification of the surface state. Thus, the body 22 may be demolded and then subjected to said radiation or, alternatively, the mold may comprise transparent parts to said radiation which allows to structure said body "in situ" that is to say without prior demolding.

Following one of these two embodiments of step 5, the method 1 continues with a step 7 for depositing on the entire body 22, a decorative layer 31 as illustrated in FIG. figure 6 . Preferably, step 7 is performed by physical deposition in phase However, other types of deposition can be envisaged, such as electroplating, chemical vapor deposition (CVD), atomic layer deposition (ALD) or even UV printing or lacquering.

Advantageously according to the invention, the last step 9 consists only of ridding the parts of the deposited layer 31 which have not adhered to the body 22 of the part 21. Indeed, thanks to the structuring according to one of the embodiments of step 5, the decorative layer 31 remains, that is to say, adhere, only at the level of the indexes 23, 25 and decor 27 under the effect of step 9. The latter 9 can, for example, be carried out by polishing, by air jet under pressure or by washing in a humid environment.

Preferably, the decorative layer 31 comprises at least one metal material which allows the dial 21 to provide an appearance that can be shiny at its raised portions 23, 25 and 27. However, other types of materials can be envisioned as, for example, metal oxides and / or metal nitrides.

Finally, if the decorative layer 31 is electrically conductive, according to a variant, following step 9, it can be envisaged to electroplate the decorations 23, 25, 27 to thicken each portion comprising said decoration.

On reading the invention above, it is therefore understood that the method 1 uses less material to form the decorative layer 31 than for the usual processes shown in FIGS. Figures 1 and 2 . In addition, the problem of positioning parts 23, 25 and 27 is limited to the quality of implementation of step 3.

Of course, the present invention is not limited to the illustrated example but is susceptible of various variations and modifications that will occur to those skilled in the art. In particular, the body 22 may be made from a material other than a plastics material such as, for example, a composite material or a ceramic. Step 3 can also be carried out by a method other than the injection into a mold presented above, such as, for example, calendering, thermoforming, compression molding, stamping and / or stamping. on press.

On reading the invention above, it is also understood that the flat surfaces of the dial 21, such as in particular the secondary display 29, can also be selectively covered with the decorative layer 31 to give an additional aesthetic effect. It suffices to provide a suitable structuring in step 5 so that said coated portions of the flat surfaces of the dial 21 remain after step 9.

Claims (11)

Method of manufacturing (1) a piece (21) in relief, which reliefs (23, 25, 27) are at least partially coated with a decorative layer (31) comprising the following step: a) forming (3) the body (22) of the workpiece (21);
characterized in that the method further comprises the following steps: b) selectively structuring (5) the surface of the body (22) of the workpiece (21) to locally modify the surface condition therein; c) depositing (7) on the entire body (22) said decorative layer; d) removing (9) the parts of the deposited layer (31) which have not adhered to the body (22) of the part. Method (1) according to claim 1, characterized in that step b) is intended to locally reduce the adhesion of the surface of the body (22) so that, in step c), the layer (31) filed does not adhere to the structured parts. Method (1) according to claim 1, characterized in that step b) is intended to locally increase the adhesion of the surface of the body (22) so that, in step c), the layer (31) deposited adheres to the structured parts. Method (1) according to one of the preceding claims, characterized in that step a) is performed by injecting material into a mold. Process (1) according to claim 4, characterized in that step b) is carried out by locally modifying the internal surface state of said mold. Method (1) according to one of claims 1 to 4, characterized in that step b) is performed by locally modifying the surface state by laser type radiation. Process (1) according to one of the preceding claims, characterized in that step c) is carried out by a physical vapor deposition. Method (1) according to one of the preceding claims, characterized in that the decorative layer (31) comprises at least one metallic material. Method (1) according to claim 8, characterized in that , after step d), an electroplating is performed in order to thicken each portion (23, 25, 27) comprising said decorative layer. Method according to one of the preceding claims, characterized in that the body (22) of the piece (21) is made of a plastic material. Method according to one of the preceding claims, characterized in that the piece (21) in relief is a timepiece dial.

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