BODYWORK PART COMPRISING A BACKLIT ZONE

Abstract

It is provided a bodywork part made of painted plastic material consisting of a single plastic material, and in one piece, comprising a first zone having a first thickness and a second zone having a second thickness, the first thickness being greater than the second thickness so that the second zone has a higher transmittance than that of the first zone.

Claims

1. Bodywork part made of painted plastic material consisting of a single plastic material, and in one piece, and comprising a first zone having a first thickness and a second zone having a second thickness, the first thickness being greater than the second thickness so that the second zone has a higher transmittance than that of the first zone.

2. Bodywork part according to claim 1, wherein the first zone is opaque or semi-opaque and the second zone is transparent or translucent.

3. Bodywork part according to claim 1, wherein the material is chosen from: translucent natural polypropylene, cycloolefin copolymers (COC), polyethylene (PE), polyamide (PA), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), mixture of polycarbonate (PC), polystyrene (PS), polymethyl methacrylate (PMMA), thermoplastic polyurethane (TPU) and polyester (PET/PETG).

4. Bodywork part according to claim 1, wherein the material is a random polypropylene copolymer, such as Moplen RP340N®.

5. Bodywork part according to claim 4, wherein the second zone has a thickness of between 0.5 and 2 mm, preferably a thickness substantially equal to 1.5 mm.

6. Bodywork part according to claim 5, wherein the first zone has a thickness of between 2.8 and 3.5 mm.

7. Motor vehicle comprising at least one bodywork part according to claim 1.

8. Method for manufacturing the bodywork part according to claim 1, comprising a molding step consisting in injecting the material into a mold to form the bodywork part and a step of painting at least on the first zone.

9. Method according to claim 8, comprising the following steps: masking the second zone; painting the entire bodywork part; removing the masking.

10. Method according to claim 8, comprising the following steps: painting the entire bodywork part; removing the paint located in the second zone using a laser beam.

11. Method according to claim 8, using an insert in the mold to obtain the second zone.

12. Method according to claim 8, wherein the second zone is obtained by removing material from the bodywork part.

13. Method according to claim 12, wherein the painting step is prior to the material removal step.

14. Method according to claim 12, wherein the material is removed by milling.

15. Method according to claim 12, wherein a quantity of material is made to creep out of the region intended to form the second zone, in order to remove the material.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0040] The various embodiments will be better understood on reading the description which follows, given solely by way of example and with reference to the appended drawings in which:

[0041] FIG. 1 is a perspective view of a motor vehicle comprising a bodywork part according to the invention;

[0042] FIG. 2 is a front view of the painted bodywork part showing transparent zones according to one example;

[0043] FIG. 3 is a schematic view of a step of a method for manufacturing the bodywork part of FIG. 2 according to one embodiment of the invention;

[0044] FIG. 4 is a schematic view of a step of a method for manufacturing the bodywork part of FIG. 2 according to another embodiment of the invention;

[0045] FIG. 5 is a schematic view of another step of the method for manufacturing the bodywork part of the embodiment illustrated in FIG. 4.

DETAILED DESCRIPTION

[0046] FIG. 1 shows a motor vehicle 100 comprising a bodywork part 1 which is a bumper according to one embodiment of the invention. The bodywork part 1 is made from a plastic material comprising a first zone 10 and a second zone 11 as visible in FIG. 2. In the illustrated example, the second zone 11 has a longitudinal shape which extends over a large part of the length of the bumper.

[0047] The bodywork part 1 is manufactured using a single-material plastic injection method which can be chosen from the following list: translucent natural polypropylene, cycloolefin copolymers (COC), polyethylene (PE), polyamide (PA), polycarbonate (PC), blend of polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polystyrene (PS), polymethyl methacrylate (PMMA), thermoplastic polyurethane (TPU) and polyester (PET/PETG).

[0048] At the end of the molding, or at the end of subsequent steps in the manufacture of the bodywork part, the first zone 10 has a first thickness and the second zone 11 has a second thickness which is smaller than the first thickness so that the second zone 11 has a better transmittance than that of the first zone 10. According to the aforementioned definitions, the first zone 10 is opaque or semi-opaque while the second zone 11 is transparent or translucent. According to one embodiment, the first thickness is preferably between 2.8 and 3.5 mm.

[0049] According to one embodiment, the bodywork part 1 is made of a material of the polypropylene random copolymer type, preferably with an average melt flow rate (MFR) (for example 11 g/10 min at 230° C./2.16 kg). An example of such a polypropylene random copolymer is Moplen RP340N® (Basell Nev., Hoofdorp, the Netherlands), which has an average melt flow rate for use in injection molding applications. Moplen RP340N is nucleated, for improved productivity and very good optical properties (transparency and gloss).

[0050] A description of this copolymer can be consulted for example in the following document: https://www.lyondellbasell.com/en/polymers/p/Moplen-RP340N/927a459e-9beb-4eb6-a995-cdb7ec73d5a0.

[0051] According to one example of this first embodiment, the first thickness is preferably between 2.8 and 3.5 mm, and the thickness of the second zone 11 is between 0.5 and 2 mm, preferably approximately 1.5 mm. Such a thickness allows the second zone 11, a thinned zone with respect to the first zone, to have a better transmittance, which can reach up to 81% transmittance for a thickness of approximately 1.5 mm.

[0052] The method for manufacturing the bodywork part consists in implementing a molding step during which the chosen material is injected into a mold to form the bodywork part 1. The resulting part is then painted. To do this, a masking is first carried out in the second zone 11. For example, a masking film is placed in the second zone 11 and is held by an adhesive. The covered part of the film corresponds to a predefined zone 12 which is intended to be unpainted and transparent. A paint is applied to the bumper 1 before the film is removed from the bumper.

[0053] As illustrated in FIG. 2, after painting and removing the film, a painted bumper 1 is obtained, except at the predefined zone 12, which remains transparent.

[0054] In an embodiment which is not shown, the second zone 11 is obtained by using an insert in the mold.

[0055] In another embodiment, the second zone 11 is obtained by removing material from the bodywork part 1.

[0056] In a variant of the embodiment by removal of material, shown in FIG. 3, the material is removed by milling. The figure shows part of the bodywork part 1 seen in section, at the end of the milling step. The part 1 comprises an outer face 102 and an inner face 104. In the example shown in FIG. 3, the outer face 102 is coated with a paint coating 112, and the inner face 104 is coated with a paint coating 114. Thus, in this example, the bodywork part 1 is painted both on its outer face 102 and on its inner face 104. The bodywork part 1 has been cut on its inner face 104 using the cutter 20, which has, by abrasion, removed material. As a result, the second zone 11 has a thickness (E) which is less than the thickness of the part 1 in the first zone 10. In this example, the painting step was prior to the material removal step. Thus, in a simple step of removing material, the second zone 11 and a precise outline of the transparent zone, which is precisely framed by the paint 114 which has remained in place, have been obtained. In a similar variation, the injected material and the paint are removed by laser scraping, rather than milling. In this case, the element 20 is a laser beam.

[0057] In another variant of the material removal embodiment, shown in FIGS. 4 and 5, a quantity of material is made to creep out of the region 13 intended to form the second zone 11. In the illustrated example, the creep is achieved using a heating means 15, such as a heating punch (which directly emits heat) or an ultrasonic punch (which emits ultrasounds which heat the material). The heating means 15 thus makes it possible to melt a quantity of plastic material from the region 13, and to cause it to creep out of the region 13.

[0058] In this example, the following steps are carried out:

[0059] The bodywork part 1 is placed on a support 14 as shown in FIG. 4,

[0060] A heating means 15 is placed near region 13 intended to form the second zone 11 or in the region 13 intended to form the second zone 11 so as to melt a quantity of material from the region 13.

[0061] The molten material 17 is made to creep into the first zone 10 so as to obtain the second thickness (E) of the second zone 11, as shown in FIG. 5.

[0062] The heating means 15 in this example consists of an ultrasonic punch having a contact surface 16 intended to come into contact with the region 13 to melt a quantity of material from this region 13 and define the shape of the second zone 11 by the creep of the molten material 17 in the first zone 10. The heating means 15 can also be a heat emitting device.

[0063] It will be understood that the second thickness (E) is precisely defined by the distance to be traveled by the heating means 15 and the pressure between the heating means 15 and the support 14. To do this, a control unit can be set up to control the movement of the heating means 15 as a function of the desired second thickness (E).

[0064] The invention is not limited to the embodiments described here, and other embodiments will become clearly apparent to a person skilled in the art. In particular, the transparency in the predefined zone 12 can also be obtained by laser scraping in this zone after the bumper has been painted in its entirety.

LIST OF REFERENCES

[0065] 1: bodywork part [0066] 10: first zone [0067] 11: second zone [0068] 12: predefined zone [0069] 13: region intended to form the second zone [0070] 14: support [0071] 15: heating medium [0072] 16: contact surface [0073] 17: molten material [0074] 20: cutter or laser beam [0075] 100: motor vehicle [0076] 102: outer face of the bodywork part [0077] 104: inner face of the bodywork part [0078] 112: outer paint coating [0079] 114: inner paint coating [0080] (E): second thickness