EP3772381A1 - Method for manufacturing a transparent vehicle part - Google Patents

Abstract

In this method of manufacturing a vehicle part (2), the following steps are implemented: - application of a layer of paint (6) on a transparent part (4), - application of a first layer of varnish (12) on the paint layer (6), - partial irradiation of the paint layer (6) and the first varnish layer (12) with laser radiation so as to etch the paint layer (6) and the first layer of varnish (12), - application of a layer of transparent primer (16) on the first layer of varnish (12), and - application of a second layer of varnish (18) on the layer of transparent primer (16).

Description

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

A vehicle comprises several transparent parts intended to transmit light. These are in particular parts used for regulatory lighting purposes, for example those protecting the optical units of high beam and low beam or flashing lights. Furthermore, the vehicle may also have light sources provided for decorative purposes which improve the aesthetics of the vehicle.

For these purposes, it is possible to treat an external surface of the transparent parts in order to improve their appearance. One possibility for this consists in overmolding a film on the external surface of the transparent part, the film having a predefined opaque pattern. In this way, when the light source associated with the transparent piece emits light, the latter is partially blocked by the opacity of the pattern and transmitted by the parts of the piece which are not covered by the pattern. This improves the aesthetics of the light beam transmitted, by the transparent part, from the light source to the external environment. Another possibility consists in decorating the transparent part by painting and marouflage, which makes it possible to obtain a similar result.

These options are interesting but can be problematic. Indeed, a film as described above can pose problems of color match with the paint of the vehicle, which has a negative impact on the aesthetics of the vehicle. In addition, applying the film in one of the ways presented above may not make it possible to obtain a pattern with as high a precision as desired.

The object of the invention is in particular to remedy this problem by proposing a method which does not pose a problem of color matching with the paint of the vehicle and which is more precise than that of the prior art.

• on applique une couche de peinture sur une pièce transparente,
• on applique une première couche de vernis sur la couche de peinture,
• on irradie partiellement la couche de peinture et la première couche de vernis avec un rayonnement laser de manière à graver la couche de peinture et la première couche de vernis,

• on applique une couche de primaire transparent sur la première couche de vernis, et
• on applique une seconde couche de vernis sur la couche de primaire transparent.

To this end, according to the invention there is provided a method of manufacturing a vehicle part comprising the following steps:

• a layer of paint is applied to a transparent part,
• a first coat of varnish is applied to the coat of paint,
• the layer of paint and the first layer of varnish are partially irradiated with a laser radiation so as to etch the paint layer and the first varnish layer,

• a layer of transparent primer is applied to the first layer of varnish, and
• a second layer of varnish is applied to the transparent primer layer.

It is thus possible to apply the paint and the first layer of varnish over the entire surface of the transparent part and then remove them by etching using laser radiation according to a chosen predefined pattern. It will be understood that the laser makes it possible to remove the paint and the first layer of varnish in order to obtain a more precise rendering than by implementing one of the methods of the prior art. In addition, thanks to the fact that the color of the coating is given by paint and not by a film as in the prior art, it is possible to choose a paint which corresponds to that used for the body of the vehicle. As a result, no color matching problem arises.

• dans le cas où elle est réalisée en polycarbonate, la pièce transparente est impossible à traiter pour la protéger des rayonnements ultraviolets, ce qui rend la présence d'au moins une couche de vernis nécessaire.
• une irradiation de la pièce de véhicule qui affecterait la pièce transparente est source de défaut pour la couche de peinture, ce qui nuirait à son aspect et à sa tenue mécanique.
• il est très difficile de faire adhérer une couche de vernis directement sur une autre couche de vernis.
• une couche de vernis appliquée directement sur la pièce transparente peut attaquer chimiquement cette dernière et la fissurer, ce qui nuirait à son aspect de surface.

The arrangement of the different layers and the order in which they are applied also makes it possible to overcome the following technical difficulties:

• in the case where it is made of polycarbonate, the transparent part is impossible to treat to protect it from ultraviolet radiation, which makes the presence of at least one layer of varnish necessary.
• an irradiation of the vehicle part which would affect the transparent part is a source of defect for the paint layer, which would adversely affect its appearance and its mechanical strength.
• it is very difficult to adhere one layer of varnish directly to another layer of varnish.
• a layer of varnish applied directly to the transparent part can chemically attack the latter and crack it, which would adversely affect its surface appearance.

Advantageously, the transparent part is manufactured by molding a plastic, for example polycarbonate, polypropylene or poly (methyl methacrylate).

The transparent part is thus simple to produce and inexpensive.

Advantageously, the laser radiation has a wavelength comprised in the infrared, preferably in the near infrared.

Such laser radiation effectively eliminates the paint layer and the first varnish layer.

Advantageously, the first and second layers of varnish are made from a material which absorbs or reflects ultraviolet radiation.

This protects the transparent part from ultraviolet radiation which could damage it by photodegradation because its entire outer surface is coated with the second layer of varnish and, in part, with the first layer of varnish.

Advantageously, the first layer of varnish is transparent to any laser radiation having a wavelength included in the near infrared.

The first layer of varnish can thus allow the laser radiation to pass without there being any risk of it being damaged by the laser radiation.

Advantageously, the first and second layers of varnish are made from the same material.

Advantageously, the paint layer comprises an opacifying primer sublayer.

The opacifying primer undercoat opacifies the paint layer and thus improves its appearance. Without an opacifying primer undercoat, it would be necessary to increase the thickness of the paint layer to obtain a similar rendering, which is preferable to avoid for reasons of appearance (sagging, tint), costs and adhesion of the paint layer to the transparent part. In addition, it improves the adhesion of the paint to the transparent part.

Advantageously, after the irradiation step, the vehicle part is polished.

This improves the transparency of the vehicle part by limiting the edge effects of the irradiated areas. Specifically, the stepped shape of the layers covering the transparent part is attenuated, which helps to make its surface appearance more homogeneous. This also helps to promote the transmission of the light beam through the vehicle part so as to maximize its illumination due to the absence of a so-called "magnifying" effect that could be caused by edge effects.

There is also provided according to the invention a vehicle part obtained by the implementation of a manufacturing method as defined in the above.

The manufacturing process improves the overall quality of the vehicle parts thus produced.

Brief description of the figures

• [Fig. 1] la figure 1 est une vue en section d'une première étape de la mise en œuvre d'un procédé de fabrication selon l'invention,
• [Fig. 2] la figure 2 est une vue en section d'une deuxième étape de la mise en œuvre d'un procédé de fabrication selon l'invention, et
• [Fig. 3] la figure 3 est une vue en section d'une troisième étape de la mise en œuvre d'un procédé de fabrication selon l'invention.

The invention will be better understood on reading the description which will follow, given solely by way of example and made with reference to the appended drawings in which:

• [ Fig. 1 ] the figure 1 is a sectional view of a first step in the implementation of a manufacturing method according to the invention,
• [ Fig. 2 ] the figure 2 is a sectional view of a second step in the implementation of a manufacturing method according to the invention, and
• [ Fig. 3 ] the figure 3 is a sectional view of a third step in the implementation of a manufacturing method according to the invention.

detailed description

One represented on the figure 1 a first step of a process for manufacturing a vehicle part 2.

The vehicle part 2 comprises a transparent part 4 intended to protect a light source (not shown). The term “transparent” is understood to mean that it is at least transparent to all light radiation having a wavelength included in the visible spectrum, that is to say between approximately 380 and 780 nm. The transparent part 4 is made here in a plastic having this characteristic, in this case polycarbonate commonly referred to as “PC”. However, provision can be made to produce the transparent part in any other plastic having this characteristic, for example polypropylene (PP) or poly (methyl methacrylate) (PMMA). The transparent part is made by molding. Since such a process is known, it will not be described in more detail in what follows.

The vehicle part 2 comprises a layer of paint 6 which is deposited on the external surface of the transparent part 4. By “external surface” is meant a surface of the transparent part which is not located opposite the source of. light and which is intended to be exposed to the external environment once the vehicle is manufactured. Here, the paint layer 6 comprises a sub-layer of opacifying primer 8 on which is deposited a base coat 10. The base coat 10 makes it possible to color the external appearance of the vehicle part 2. The sub-layer of opacifying primer 8 makes it possible to improve the opacity of the paint layer 6 and to improve the adhesion of the base layer 10 to the transparent part 4.

The vehicle part 2 comprises a first layer of varnish 12 which is deposited on an external surface of the transparent part 4, above the layer of paint 6.

According to the first step of the process for manufacturing the vehicle part 2, the layer of paint 6 is deposited then the first layer of varnish 12 on the transparent part 4.

We have represented in figure 2 a second step of the process for manufacturing the vehicle part 2. In this step, a part of the vehicle part 2 is irradiated with the aid of laser radiation 14 so as to etch the paint layer 6 and the first layer of varnish 12. This etching is carried out throughout the thickness of the layer of paint 6 and of the first layer of varnish 12. This operation is commonly designated by the English terms “laser-etching” which can be translated as “ laser engraving ”. The laser radiation 14 has a wavelength comprised in the infrared, that is to say comprised between 700 nm and 20,000 nm in the context of the invention. An example of such laser radiation is that commonly referred to as a “CO ₂ laser” which has a wavelength of 10600 nm. Preferably, the wavelength of the laser radiation 14 is included in the near infrared, that is to say between 700 and 2000 nm. In this case and if the first layer 12 of varnish is transparent to laser radiation 14, the latter has the advantage of not etching the first layer of varnish. This avoids a risk of damaging the varnish layer.

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 of the external surface of the first layer of varnish 12. It is controlled so that the layer of paint 6 and the first layer of varnish 12 is irradiated, therefore eliminated in the pattern and in all their thickness. Even if the first layer of varnish 12 is made of a material transparent to laser radiation 14, the irradiation of the underlying paint layer 6 makes it possible to eliminate the first layer of varnish 12 in the pattern. After the irradiation, the surface of the vehicle part 2 has two levels.

In the area of the predefined pattern, the transparent part 4 is no longer coated. In this area, visible light can be transmitted from the light source to the outside environment, and vice versa.

Outside the zone of the predefined pattern, the transparent part 4 is coated with the layer of paint 6 and the first layer of varnish 12. In this zone, visible light cannot be transmitted from the external environment to the transparent part. 4, and vice versa, because it is absorbed by the paint layer 6.

After this irradiation step, a step of polishing the vehicle part 2 can be provided. It makes it possible to improve the transparency in the zone of the predefined pattern and, more generally, the aesthetics of the vehicle part 2. In addition, this buffing makes it possible to round off the corners formed by the etching carried out during the irradiation step, and therefore to improve the aesthetics of the vehicle part 2.

We have represented in figure 3 a third step of the process for manufacturing the vehicle part 2. In this step, a layer of transparent primer 16 is deposited on the transparent part 4, above the layer of paint 6 and the first layer of varnish 12. As shown in the figure 3 , the transparent primer notably fills the areas in the pattern which have undergone the etching described in the above. This primer being transparent, it does not prevent the transmission of a light beam in the visible spectrum.

Next, a second layer of varnish 18 is deposited on the transparent part 4, above the transparent primer layer 16. The latter makes it possible to deposit the second layer of varnish 18, insofar as it is very difficult to remove. to do adhere a layer of varnish to another layer of varnish, whatever the nature of these two layers of varnish.

The second layer of varnish 18 has the particular function of protecting the transparent part 4 from any ultraviolet radiation to which it may be exposed, in particular from the sun. In addition, the second layer of varnish 18 makes it possible to mechanically protect the transparent part 4, in particular to prevent it from being scratched or deformed by external stresses. Here, the first 12 and second 18 layers of varnish are made from the same material, but it is possible to use two different varnishes to make the two layers 12, 18.

At this time, the coating of the vehicle part 2 has two different structures.

In the area of the predefined pattern, the transparent part 4 is coated with the transparent primer layer 16 and the second layer of varnish 18. In this area, visible light can be transmitted from the light source to the external environment, and vice versa. The transparent primer layer 16 improves the adhesion of the second layer of varnish 18 to the transparent part 4. It also makes it possible to avoid direct contact between the second layer of varnish 18 and the transparent part 4, to which case the transparent part could be chemically attacked by the varnish.

Outside the zone of the predefined pattern, the transparent part 4 is coated with the layer of paint 6, the first layer of varnish 12, the transparent primer layer 16 and the second layer of varnish 18. In this zone, visible light cannot be transmitted from the external environment to the transparent part 4, and vice versa, because it is absorbed by the paint layer 6.

The invention is not limited to the embodiments presented and other embodiments will be apparent to those skilled in the art.

The light source may form part of an optical unit for the low beam and main beam of the vehicle, of an optical unit of flashing lights of the vehicle, or else of an optical unit of decorative lights.

Alternatively, the transparent part can integrate light guides or light sources without an optical unit, by insert molding, overmolding, fixing by gluing, welding, riveting or any other fixing means.

List of references

• 2: vehicle part
• 4.transparent part
• 6: paint coat
• 8: opacifying primer undercoat
• 10: base coat
• 12: first coat of varnish
• 14: laser radiation
• 16: transparent primer
• 18: second coat of varnish

Claims (9)

Method of manufacturing a vehicle part (2), characterized in that it comprises the following steps: - application of a layer of paint (6) on a transparent part (4), - application of a first layer of varnish (12) on the layer of paint (6), - partial irradiation of the paint layer (6) and of the first varnish layer (12) with laser radiation (14) so as to etch the paint layer (6) and the first varnish layer (12), - application of a layer of transparent primer (16) on the first layer of varnish (12), and - application of a second layer of varnish (18) on the transparent primer layer (16). Process according to the preceding claim, in which the transparent part (4) is manufactured by molding a plastic, for example polycarbonate, polypropylene or poly (methyl methacrylate). Method according to any one of the preceding claims, in which the laser radiation (14) has a wavelength comprised in the infrared, preferably in the near infrared. Method according to any one of the preceding claims, in which the first and second varnish layers (12, 18) are made from a material capable of absorbing or reflecting ultraviolet radiation. Method according to any one of the preceding claims, in which the first varnish layer (12) is transparent to any laser radiation having a wavelength comprised in the near infrared. Method according to any one of the preceding claims, in which the first and second varnish layers (12, 18) are made of the same material. Method according to any one of the preceding claims, in which the paint layer (6) comprises an undercoat of opacifying primer (8). A method according to any one of the preceding claims, wherein after the irradiation step, the vehicle part (2) is polished. Vehicle part (2), characterized in that it is obtained by implementing a manufacturing method according to any one of the preceding claims.

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