FR3089848A1 - Method for overmolding optical fibers in a bodywork part - Google Patents

Abstract

The invention relates to a method of manufacturing a bodywork part (2) comprising a main body (4) made of at least partially transparent or translucent plastic material and at least one bundle of optical fibers (6) capable of diffusing light through the main body, the method comprising the following steps: - the bundle of optical fibers (6) is placed in an injection mold, and - the bundle of optical fibers (6) is overmolded in the main body (4 ) by injecting plastic material inside the mold. Figure for the abstract: Fig. 1

Description

Description

Title of the invention: Method for overmolding optical fibers in a bodywork part

The invention relates to motor vehicle body parts and more particularly the methods of manufacturing such parts, in particular those comprising a light signature.

It is more and more common that motor vehicles include, at their bodywork, light points or light beams forming a light signature constituting an element of personalization of the vehicle.

It is known, to achieve such a light signature, to produce a bodywork part, for example by injection molding. Next, optical fibers, for example a sheet of optical fibers, are attached to the part by fixing it to the latter, for example by gluing.

Such a process has several drawbacks.

First, it is necessary to take the part back after its manufacture, which monopolizes significant human and material resources in a sector of activity having to respect industrial rates. This recovery stage is moreover more complex and less repeatable industrially than the manufacture of the bodywork part.

In addition, the optical fibers are not optimally protected because exposed to external conditions, which leads to anticipated degradation of the latter.

The optical fibers used are optical fibers having undergone a treatment aimed at degrading their surface (sanding or scraping) in order to diffuse light over their entire length. It is therefore not possible to use all types of optical fibers to achieve a light signature.

Finally, the scattering of light through the room is not optimal. In fact, an assembly as described above can allow air to pass between the optical fibers and the part, which leads to a deterioration in the quality of the light signature.

The object of the invention is to provide a bodywork part comprising a durable and quality light signature by means of a simpler process than existing processes.

To this end, the invention relates to a method of manufacturing a bodywork part comprising a main body made of plastic material at least partially transparent or translucent and at least one bundle of optical fibers capable of diffusing the light through the main body, the method comprising the following steps:

The fiber optic bundle is placed in an injection mold, and

The bundle of optical fibers is overmolded in the main body by injecting plastic material inside the mold.

Thus we obtain a bodywork part comprising a light signature without having to perform a recovery step of the part because the latter comprises, from its molding, the means allowing the light signature to be produced.

In addition, the optical fibers are better protected and are not subject to sealing problems which can degrade the quality of the light signature, and the light scattering through the bodywork is of better quality. Optical fibers can in fact be placed near the external face of the part visible from outside the vehicle.

Finally, overmolding makes it possible to at least partially dispense with any prior surface treatment such as those described above. It is therefore possible to use a larger range of optical fibers, in particular cheaper optical fibers than in the prior art thanks to the absence of prior treatment of the latter.

The method according to the invention can also include at least one of the following characteristics:

Using a bundle of optical fibers having not undergone any prior treatment of degradation of a surface of the bundle of optical fibers over at least part of its length;

The optical fiber bundle is capable of diffusing light over the length having not undergone any prior degradation treatment after the overmolding step;

The plastic is injected at a temperature between 200 ° C and 350 ° C;

The pressure inside the mold during overmolding is between 250 bars and

500 bars;

The bundle of optical fibers is placed in the mold in a direction parallel to a direction of flow of the injected plastic;

The method further comprises the following steps:

Placing a first part of the main body comprising at least one groove in the mold,

Placing the bundle of optical fibers in the groove, and

The optical fiber bundle is overmolded in the main body by producing a second part of the main body by injection of plastic material;

The main body is overmolded on another part of the bodywork part after overmolding the bundle of optical fibers; and

The plastic material injected is chosen from: polypropylene, thermoplastic polyurethane, a polyamide, polymethyl methacrylate, a copolyester,

1 acrylonitrile butadiene styrene, Γ acrylonitrile styrene acrylate, styrene-acrylonitrile, a mixture of acrylonitrile styrene acrylate and polycarbonate, a mixture of polycarbonate and polyethylene terephthalate, polycarbonate, cyclo-olefin copolymers or cyclo polymer olefins.

Brief description of the figures

We will now present embodiments of the invention given by way of nonlimiting example and with the support of the appended figures in which:

[Fig.l] represents a portion of bodywork part according to the invention comprising a bundle of optical fibers;

[fig.2] shows an embodiment of a main body according to the invention; and [fig.3] shows an example of integration of optical fibers according to the invention.

detailed description

Referring now to Figure 1 illustrating a portion of a bodywork part 2, which could for example be a bumper or a tailgate, comprising a main body 4 and, in the example illustrated, a bundle of optical fibers 6 capable of diffusing light through the main body 4. For this purpose, the main body 4 is made at least partially from a transparent or translucent material. “Transparent” means a material transmitting light by refraction and through which objects are clearly visible. “Translucent” is understood to mean a material transmitting light in a diffuse manner and through which objects appear blurred.

In this example, we deal with a bundle of optical fibers alone (or single bundle). The invention can also be implemented with a sheet of optical fibers, for example composed of aligned fibers.

A portion 8 of the bundle of optical fibers 6 is encapsulated in the main body 4. In the methods according to the prior art, the bundle of optical fibers is attached to the main body with the drawbacks mentioned above. In the method according to the invention, the bundle of optical fibers 6 (the portion 8 in FIG. 1) is molded into the main body 4. Consequently, a step of taking up the bodywork part 2 after molding is avoided, the Optical fibers are better protected and are not prone to leakage problems, and the scattering of light through the bodywork is better. The bundle of optical fibers can for example be composed of glass fibers or of polymethyl methacrylate.

In addition, it has been observed that, unexpectedly, the overmolding of the bundle of optical fibers 6 makes it possible to at least partially dispense with any prior surface treatment such as one of those described above, obtaining a visual effect. identical. The term “surface treatment” is understood to mean any treatment, for example mechanical of the sanding or scraping type, aimed at degrading the outer layer of a bundle of optical fibers in order to allow the diffusion of light over the entire periphery of the bundle of optical fibers, diffusion represented by the arrows 10 in FIG. 1 (referenced only in part for reasons of readability). In other words, injection molding makes it possible to dispense with any surface treatment by constituting an equivalent of the latter, the bundle of optical fibers 6 being capable of diffusing light along its surface after having been molded. Untreated optical fibers are also compatible with more materials and can be exposed to greater pressure and temperature ranges. It is possible to pretreat a portion of the bundle of optical fibers 6 before overmolding the latter, in particular a portion located in a part of the injection mold where the pressure and the temperature are lower during the molding operations.

This finding that there is no need for treatment is contrary to the prejudice inherent in this type of process according to which prior treatment of the bundle of optical fibers 6 is essential for obtaining a good light signature.

Finally, the bundle of optical fibers 6 can be placed near the external face of the part visible from outside the vehicle when the bodywork part 2 is mounted on a motor vehicle.

In order to overmold the bundle of optical fibers 6 in the main body 4, the latter is placed in an injection mold making it possible to produce the main body 4 and then the plastic is injected into the mold. This is, concerning the injection molding process, a process conventionally used by a person skilled in the art, in particular as regards the mold and its operation or even the plastic injection process. “Plastic material” means any plastic material which can be injected into an injection mold, in particular thermoplastic materials.

The plastic material used can for example be chosen from polypropylene, thermoplastic polyurethane, a polyamide, polymethyl methacrylate, a copolyester, acrylonitrile butadiene styrene, acrylonitrile styrene acrylate, styreneacrylonitrile, a mixture of acrylonitrile styrene acrylate and polycarbonate, a mixture of polycarbonate and polyethylene terephthalate, polycarbonate, copolymer cyclo-olefins or polymer cyclo-olefins.

In general, the plastic material chosen allows good diffusion of the light emitted by the optical fiber bundle 6. Indeed, the use of plastic material diffusing light optimally, for example cyclo-olefins copolymers (or COC), reduces the number of interfaces necessary to obtain an optimal visual effect. Certain plastic materials may be chosen preferentially as a function of their capacity to allow a transparent or translucent main body 4 to be obtained and of their capacity to maintain a transparent or translucent appearance over time.

Concerning the copolymer cyclo-olefins, they have the advantage of making it possible to have more flexibility in the design of the body parts produced and to resist shock and ultraviolet rays.

In addition, the translucent or transparent plastic material can be used to make the entire main body 4 or only a part of the latter, for example by implementing a bi-injection process.

The thermoplastic material injected after placing the bundle of optical fibers 6 in the injection mold is injected at a temperature between 200 ° C and 300 ° C and at a pressure between 250 bar and 400 bar.

The bundle of optical fibers 6 can be placed in a direction parallel to a direction of flow of the plastic in the mold. This makes it possible to avoid a phenomenon of drift of the bundle of optical fibers 6 during the flow of the plastic material and consequently obtaining a main body 4 in which the bundle of optical fibers 6 would not be at the desired location.

In order to prevent the drift of the optical fiber bundle 6, it is also possible, for example in addition to placing the optical fiber bundle 6 in a direction parallel to the direction of flow of the injected plastic, implementing the process steps illustrated in FIGS. 2A to 2C.

For this, first place in the mold a first part 12 of the main body 4. This first part 12 can be made of a transparent, translucent or even opaque material. This first part 12 comprises a groove 14 in which it is possible to place the bundle of optical fibers 6.

Once the bundle of optical fibers 6 is placed in the groove 14 of the first part 12 of the main body 4 inside the mold, the plastic is injected, for example a transparent or translucent thermoplastic, in order making a second part 16 of the main body 4 and overmolding the first part 12 / bundle of optical fibers 6.

The main body 4, at least partially made of a transparent or translucent material, can constitute the entire body of the bodywork part 2. It is also possible that the main body 4 is only a part of the body of the bodywork part 2.

In this case, and after overmolding the bundle of optical fibers 6 in the main body 4, this assembly is used to produce a part of the body of the bodywork part 2.

We can for example consider that this assembly is molded in another room to obtain the bodywork part 2. We could also consider bringing this assembly by clipping, bonding or any other conventional means known to those skilled in the art. job.

Figures 3A to 3C illustrate this case in which the main body 4 / optical fiber bundle 6 assembly is present on the periphery of a part 18 of a bodywork part after overmolding or after having reported this together on part 18, all of these two elements forming the bodywork part 2, a portion of which is shown in FIGS. 3A to 3C. The bundle of optical fibers 6 can then diffuse light laterally in the part 18 from the periphery of the latter.

The invention is not limited to the embodiments presented and other embodiments will be apparent to those skilled in the art. It is in particular possible to modify the shape of the groove produced in the first part of the main body, or even its direction of extension.

List of numerical references

2: bodywork part: main body: optical fiber bundle: portion of the optical fiber bundle: directions of the light rays: first part of the main body: groove: second part of the main body: part of the bodywork part

Claims (1)

Claims [Claim 1] Method for manufacturing a bodywork part (2) comprising a main body (4) made of at least partially transparent or translucent plastic material and at least one bundle of optical fibers (6) capable of diffusing light through the body main, the method being characterized in that it comprises the following stages: - the bundle of optical fibers (6) is placed in an injection mold, and - the bundle of optical fibers (6) is overmolded in the main body (4) by injecting plastic material inside the mold. [Claim 2] Method according to claim 1, in which an optical fiber bundle (6) is used which has not undergone any prior degradation treatment of a surface of the optical fiber bundle (6) over at least part of its length. [Claim 3] Method according to any one of the preceding claims, in which the optical fiber bundle (6) is capable of diffusing light over the length which has not undergone any prior degradation treatment after the overmolding step. [Claim 4] Method according to any one of the preceding claims, in which the plastic material is injected at a temperature between 200 ° C and 350 ° C. [Claim 5] Method according to any one of the preceding claims, in which the pressure inside the mold during overmolding is between 250 bars and 500 bars. [Claim 6] Method according to any one of the preceding claims, in which the bundle of optical fibers (6) is placed in the mold in a direction parallel to a direction of flow of the injected plastic. [Claim 7] Method according to any one of the preceding claims, further comprising the following steps: a first part (12) of the main body (4) is placed in the mold comprising at least one groove (14), the fiber optic bundle (6) is placed in the groove (14), and - The bundle of optical fibers (6) is overmolded in the main body (4) by producing a second part (16) of the main body (4) by injection of plastic material. [Claim 8] Method according to any one of the preceding claims, in which the main body (4) is overmolded on another part (18) of the bodywork part after overmolding of the optical fiber bundle (6). [Claim 9] Process according to any one of the preceding claims, in which the plastic material injected is chosen from: polypropylene, thermoplastic polyurethane, a polyamide, polymethyl methacrylate, a copolyester, acrylonitrile butadiene styrene, 1 ' acrylonitrile styrene acrylate, styrene-acrylonitrile, a mixture of acrylonitrile styrene acrylate and polycarbonate, a mixture of polycarbonate and polyethylene terephthalate, polycarbonate, copolymer cyclo-olefins or polymer cyclo-olefins.