Manufacturing process for a vehicle part

Abstract

This process for manufacturing a vehicle part (2) comprises a step of applying a layer of paint (6) to one face of a transparent or translucent part (4), and a step of partially irradiating the paint layer (6) with laser radiation (10) so as to etch the paint layer (6) according to a predefined pattern and within a portion of its thickness. Figure 2 for the abbreviation

Description

Title of the invention: Method for manufacturing a vehicle part

[0001] The invention relates to a motor vehicle part. More particularly, the invention relates to a method for manufacturing a transparent vehicle part that contributes to the exterior appearance of the vehicle.

[0002] A vehicle includes several transparent parts designed to transmit light. These include parts used for regulatory lighting purposes, such as those protecting the optical units of the high and low beam headlights or the turn signals. Furthermore, the vehicle may also have light sources designed for decorative purposes that enhance the vehicle's aesthetics.

[0003] To this end, it is possible to treat the surface of transparent parts to improve their appearance. One way to do this is to overmold a film onto the surface of the transparent part, the film having a predefined opaque pattern. In this way, when the light source associated with the transparent part emits light, the light is partially blocked by the opacity of the pattern and transmitted through the parts of the part not covered by the pattern. This improves the aesthetics of the light beam transmitted, through the transparent part, from the light source to the external environment. Another possibility is to decorate the transparent part by painting and applying a coating, which achieves a similar result.

[0004] These options are interesting but can present problems. Indeed, a film as described above or a masking technique can cause color matching issues with the vehicle's paint, which negatively impacts the vehicle's appearance. Furthermore, applying the film or masking may not allow for a pattern of the desired high precision. In addition, these techniques can lead to problems with aging.

[0005] To remedy these problems, it is known, for example from document FR 1912347 A1, to apply a layer of paint to a transparent part and then engrave it by laser irradiation according to a predefined pattern. The paint layer is then removed to its full thickness in the area of ​​the pattern, which allows light to pass through the transparent part in the pattern area. However, this solution is not entirely satisfactory insofar as a problem remains with the passage of light through the parts of the transparent part that are not covered by the pattern. Indeed, light is transmitted freely through these parts, so that the elements behind the part are visible from the outside if the light source associated with the transparent part is switched off. These are mainly the light source and possibly wiring elements. The exposure of these elements is not not desirable as it detracts from the overall aesthetics of the vehicle, so it is best to avoid it.

[0006] The invention aims in particular to remedy these problems by proposing a method which does not pose a problem of color matching with the vehicle's paint, which is more precise than that of the prior art and which allows the elements located behind the transparent piece to be concealed.

[0007] To this end, the invention relates to a method for manufacturing a vehicle part comprising the following steps:

[0008] - application of a layer of paint to one side of a transparent part or translucent, and

[0009] - partial irradiation of the paint layer with laser radiation in a manner to engrave the paint layer according to a predefined pattern and in a part of its thickness.

[0010] Paint can thus be applied to one face of the transparent part and then partially removed through its thickness by laser engraving according to a predefined pattern. In other words, only a residue of the paint layer remains in the area of ​​the predefined pattern. It is understood that the laser makes it possible to remove the paint to obtain a more precise finish than by implementing one of the prior art processes discussed above. Furthermore, the fact that the coating color is provided by paint and not by a film or a masking as in the prior art allows for the selection of a paint that matches that used for the vehicle's body. Consequently, fewer color matching problems arise.Furthermore, the manufacturing process involves only a single coating application step on the transparent or translucent part, namely the paint layer, so the process requires only one pass through a paint deposition workshop or line (understood here in the broadest sense). This contributes to making the manufacturing process simple and quick to implement and, more generally, to making the manufacturing process more industrially competitive.

[0011] The residual paint layer present in the pattern area prevents visibility through the transparent or translucent part when a light source is connected to the transparent or translucent part and switched off, without preventing the transmission of light emitted by the light source when it is switched on. It is thus understood that the elements located behind the transparent or translucent part do not negatively impact the aesthetics of the vehicle since they are obscured by the paint layer.

[0012] Advantageously, the paint layer is a lacquer layer.

[0013] The term "lacquer" means a paint with a hardener. By way of example, lacquer can be made from thermosetting resins, in particular Alkyd, glycerophthalic, or polyurethane-based lacquers allow for a colored finish with a layer thickness much less than that required with conventional paint.

[0014] Advantageously, the paint layer comprises a transparent primer undercoat. Advantageously, the lacquer layer comprises a transparent primer undercoat.

[0015] Advantageously, the laser radiation has the following parameters: wavelength in the infrared, working power between 5 and 10 W, scanning speed between 1800 and 2200 mm / s, pulse frequency between 25000 and 35000 Hz.

[0016] This allows for engraving the paint layer in a part of its thickness in a particularly controlled and reproducible manner.

[0017] Advantageously, the paint layer has a thickness of between 1 and 8 pm in the predefined pattern after partial irradiation.

[0018] Such a thickness corresponds to a good compromise between the transmission of light through the paint layer residue in the pattern area and the concealment of the light source when it is switched off.

[0019] Advantageously, the transparent or translucent part is manufactured by molding a plastic, for example polycarbonate (PC), polypropylene (PP), polyamide (PA), polyethylene terephthalate (PET), polyethylene butylene terephthalate (PBT), polyurethane (PU), polyvinyl chloride (PVC), acrylonite butadiene styrene (ABS), styrene acrilonitrile (SAN), acrilonitrile styrene acrylate (ASA), polymethyl methacrylate (PMMA), cyclo-olefin copolymer (COC) or cyclo-olefins-polymer (COP).

[0020] The transparent or translucent part is thus simple to produce and inexpensive.

[0021] Advantageously, the paint layer is opaque, and preferably colored black or grey.

[0022] The opacity of the paint or lacquer makes it possible to improve the quality of the lighting of the pattern made by a light source placed behind the vehicle part, by preventing the formation of a blurry light halo on the edges of the pattern.

[0023] Advantageously, a light source is installed opposite the paint layer.

[0024] The paint layer is thus intended to be oriented towards the inside of the vehicle when the vehicle part is installed in a vehicle. In this way, it is not necessary to protect the paint layer from external damage, for example from mechanical stress or ultraviolet radiation from the sun.

[0025] The invention also provides for a vehicle part comprising a transparent or translucent piece on which is deposited a layer of paint having a first thickness in a predefined pattern and a second thickness outside the predefined pattern, the first thickness being less than the second thickness.

[0026] Advantageously, the vehicle part has, in the predefined pattern, a haze coefficient, or “coefficient of haze”, greater than or equal to 60%, preferably greater than or equal to 75%, for example about 80%, preferably greater than or equal to 90%.

[0027] Advantageously, the vehicle part has, in the predefined pattern, a transparency greater than or equal to 20%, preferably greater than or equal to 30%, preferably between 35% and 45%.

[0028] These values ​​represent a good compromise between the transmission of light through the paint layer in the pattern area and the concealment of the light source when it is switched off.

[0029] Advantageously, the vehicle part further includes a light source installed opposite the paint layer. Brief description of the figures

[0030] The invention will be better understood upon reading the following description, given solely by way of example and made with reference to the accompanying drawings in which:

[0031] [Fig-1] is a sectional view of a first step in the implementation of a process manufacturing a vehicle part according to an embodiment of the invention,

[0032] [Fig.2] is a sectional view of a second step in the implementation of a method for manufacturing a vehicle part according to an embodiment of the invention, and

[0033] [Fig.3] is a sectional view of a third step in the implementation of a method for manufacturing a vehicle part according to an embodiment of the invention. Detailed description

[0034] Figure [1] shows a first step of a manufacturing process for a vehicle part 2 according to an embodiment of the invention.

[0035] The vehicle part 2 includes a transparent or translucent part 4 intended to protect a light source. "Transparent" and "translucent" respectively mean that it is at least transparent and translucent to all light radiation having a wavelength within the visible spectrum, i.e., between approximately 380 and 780 nm. The part 4 is transparent here and made of a plastic having this characteristic, in this case polycarbonate, commonly referred to as "PC". However, the part can be made of a completely different plastic, for example polypropylene (PP), polyamide (PA), polyethylene terephthalate (PET), polyethylene butylene terephthalate (PBT), polyurethane (PU), polyvinyl chloride (PVC), etc. Acrylonite butadiene styrene (ABS), styrene acrilonitrile (SAN), acrylonitrile styrene acrylate (ASA), polymethyl methacrylate (PMMA), cycloolefin copolymer (COC), or cycloolefin polymer (COP) are all suitable materials. The transparent or translucent part 4 is produced by molding. Since this process is well-known, it will not be described in further detail below.

[0036] The vehicle part 2 comprises a paint layer 6 which is deposited on a first transparent or translucent face of the part 4, this first face being intended to face the interior of the vehicle when the vehicle part 2 is installed in a vehicle. The paint layer is here a lacquer layer 6, but the invention can be implemented with a so-called "conventional" paint layer. By "lacquer," we mean a paint with a hardener. By way of example, the lacquer can be made from thermosetting resins, in particular alkyd or glycerophthalic resins, or from polyurethanes. Here, the lacquer layer 6 is opaque. Preferably, it is black or gray. The lacquer layer 6 has a thickness of approximately 25 µm.Optionally, a clear primer undercoat is applied under the lacquer 6 coat; if so, the clear primer undercoat has a thickness of between 25 and 30 µm. In what follows, the term "lacquer coat" will refer to the lacquer 6 coat itself and the clear primer undercoat if present.

[0037] The vehicle part 2 includes a varnish layer 8 which is deposited on a second face of the transparent or translucent part 4 opposite the first face. In other words, the varnish layer 8 and the paint layer 6 are deposited on opposite faces of the transparent or translucent part 4. The varnish layer 8 protects the transparent or translucent part 4 from any ultraviolet radiation to which it may be exposed, particularly from the sun. This is especially advantageous if the transparent or translucent part 4 is made of polycarbonate.

[0038] According to the first step of the manufacturing process for vehicle part 2, the varnish layer 8 and the lacquer layer 6 are deposited onto the transparent or translucent part 4. The lacquer layer 6 has sufficient thickness to completely absorb any beam of light in the visible spectrum. This thickness is between 25 and 50 µm.

[0039] A second step in the manufacturing process of vehicle part 2 is shown in [Fig. 2]. In this step, a portion of vehicle part 2 is irradiated with laser radiation 10 to etch the lacquer layer 6. This operation is commonly referred to by the English term "laser etching." The laser radiation 10 has the following parameters: wavelength in the infrared range, working power between 5 and 10 W, scanning speed between 1800 and 2200 mm / s, frequency of The pulse rate is between 25,000 and 35,000 Hz. As an example, the laser beam 10 has the following parameters: wavelength of 1064 nm, working power of 8 W, scanning speed of 2000 mm / s, and pulse rate of 30,000 Hz. Irradiation by the laser beam 10 burns the lacquer layer 6 in the pattern area, leaving only burnt residue of this layer. The laser beam is parameterized to achieve this result. In the pattern area, some of the residue migrates into the transparent or translucent part 4, forming a thin residual lacquer layer. This layer is low-density, heterogeneous, and has a sparse, grainy appearance, resulting in diffuse light transmission.

[0040] The irradiation is carried out only in a part of the vehicle part 2 in the sense that it is carried out according to a predefined pattern formed on the lacquer layer 6. It is controlled so that the lacquer layer 6 is irradiated in the pattern but only in a part of its thickness, but not the transparent or translucent part 4. If present, the transparent primer undercoat protects the transparent or translucent part 4 from the heat effect of the laser radiation 10 by creating a separation distance between the irradiated lacquer layer 6 and the transparent or translucent part 4. It has indeed been observed that the transparent or translucent part 4 tends to yellow, particularly if it is made of polycarbonate, under the effect of the laser radiation 10 without the presence of the primer undercoat.

[0041] After irradiation, the lacquer layer 6 has two levels.

[0042] In the area of ​​the predefined pattern, the lacquer layer 6 is present in a first thickness equal to a fraction of its original thickness, here between 1 and 8 µm. In this area, the vehicle part 2 has a haze coefficient, or more commonly referred to as the "coefficient of haze" in English, greater than or equal to 60%, preferably greater than or equal to 75% and preferably greater than 90%, and has a transparency greater than or equal to 20%, preferably greater than or equal to 30% and preferably between 35% and 45% (ideally equal to 40%).

[0043] Outside the area of ​​the predefined pattern, the lacquer layer 6 is intact and has a second thickness equal to the thickness of the lacquer layer 6 as deposited. The first thickness is therefore less than the second thickness.

[0044] After the irradiation step, an additional polishing step can be carried out on the transparent or translucent part 4. This improves the transparency in the area of ​​the predefined pattern and, more generally, the aesthetics of the vehicle part 2. In addition, this polishing rounds off the corners formed by the engraving carried out during the irradiation step, and thus reduces light scattering phenomena that could disrupt a light beam passing through the part. vehicle 2.

[0045] A third step in the manufacturing process of the vehicle part 2 is shown in [Fig. 3]. In this step, which occurs after the irradiation step, a light source 12 is connected to the transparent or translucent part 4. Here, the light source 12 is positioned opposite the lacquer layer 6, so that the latter faces the interior of the vehicle when the vehicle part 2 is installed in a vehicle. In other words, the lacquer layer 6 is deposited on the side of the transparent or translucent part 4 (first side) opposite the side of the transparent or translucent part 4 visible from the outside (second side) when the vehicle part 2 is installed in the vehicle. This configuration is generally referred to as the lacquer layer 6 being located on side B, or "B-side." The varnish layer 8 is deposited on side A, or "A-side."Thus, the first and second faces previously introduced correspond respectively to face B and face A.

[0046] When the light source 12 is switched off, so that it does not emit light, it is not visible through the transparent or translucent piece 4 due to the presence of the lacquer layer 6, over its entire thickness outside the pattern area and over the partial thickness in the pattern area.

[0047] When the light source 12 is switched on, so that it emits light towards the transparent or translucent part 4, the light is transmitted through the partial lacquer layer 6 in the pattern area and blocked by the lacquer layer 6 outside the pattern area. Because the lacquer layer 6 is opaque, and moreover black or gray in color, it does not alter the color of the transmitted light very much, and the light transmission occurs without the formation of a blurry halo of light at the edges of the pattern area.

[0048] The invention is not limited to the embodiments shown and other embodiments will be obvious to a person skilled in the art.

[0049] The light source may be part of a vehicle's low beam and high beam optical unit, a vehicle's turn signal optical unit, or a decorative light optical unit.

[0050] The paint or lacquer can be made from a colored material. In this way, the diffusion of light, emitted by the light source, through the partial layer of lacquer is accompanied by a coloring of the light, which gives it a certain aesthetic effect.

[0051] An alternative embodiment can be envisaged in which the paint or lacquer layer is deposited on face A of the transparent or translucent part. In this case, the varnish layer is deposited above the paint or lacquer layer, and face B of the transparent or translucent part, in front of which The light source is placed there, it can be left bare. List of references

[0052] 2: vehicle part 4: transparent or translucent piece 6: coat of paint / coat of lacquer 8: layer of varnish 10: laser radiation 12: light source

Claims

Demands

1. A method for manufacturing a vehicle part (2), characterized in that it comprises the following steps: - application of a layer of paint (6) on one face of a transparent or translucent part (4), and - partial irradiation of the layer of paint (6) with laser radiation (10) so as to engrave the layer of paint (6) according to a predefined pattern and in a part of its thickness.

2. Method according to the preceding claim, wherein the paint layer (6) is a lacquer layer.

3. A method according to any one of the preceding claims, wherein the laser radiation (10) has the following parameters: wavelength in the infrared, working power between 5 and 10 W, scanning speed between 1800 and 2200 mm / s, pulse frequency between 25000 and 35000 Hz.

4. A method according to any one of the preceding claims, wherein the paint layer (6) has a thickness of between 1 and 8 pm in the predefined pattern after partial irradiation.

5. A method according to any one of the preceding claims, wherein the transparent or translucent part (4) is manufactured by molding a plastic, for example polycarbonate, polypropylene, polyamide, polyethylene terephthalate, butylene terephthalate, polyurethane, polyvinyl chloride, acrylonite butadiene styrene, styrene acrilonitrile, acrilonitrile styrene acrylate, polymethyl methacrylate, cyclo-olefin copolymer or cyclo-olefins-polymer.

6. A method according to any one of the preceding claims, wherein the paint layer (6) is opaque, and preferably black or grey in color.

7. A method according to any one of the preceding claims, wherein a light source (12) is installed opposite the paint layer (6).

8. Vehicle part (2), characterized in that it comprises a transparent or translucent part (4) on which is deposited a layer of paint (6) having a first thickness in a predefined pattern and a second thickness outside the predefined pattern, the first thickness being less than the second thickness.

9. Vehicle part (2) according to claim 8, having, in the predefined pattern, a haze coefficient, or “coefficient of haze”, greater than or equal to 60%, preferably greater than or equal to 75%, preferably greater than or equal to 90%.

10. Vehicle part (2) according to claim 8 or 9, having, in the predefined pattern, a transparency greater than or equal to 20%, preferably greater than or equal to 30%, preferably between 35% and 45%.

11. Vehicle part (2) according to any one of claims 8 to 10, further comprising a light source (12) installed opposite the paint layer (6).

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