Process for manufacturing a transparent or translucent vehicle part

Abstract

The invention relates to a method for manufacturing a bodywork part (2) of a motor vehicle, characterized in that it comprises the following steps: - depositing at least one opaque coating on at least a portion of a face (6) of a main body (3) of the bodywork part (2), the main body (3) being made of transparent or translucent plastic material, and - producing a set of microperforations (8, 10) of the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, an irradiation path (12, 16, 22) of the laser beam consisting solely of successive substantially rectilinear path lines (12', 16', 22'). Figure for the abstract: figure 2

Description

Title of the invention: Method for manufacturing a transparent or translucent vehicle part

[0001] The invention relates to a motor vehicle part. More particularly, the invention relates to a method for manufacturing a transparent or translucent vehicle part contributing to the exterior appearance of the vehicle and a device for carrying out such a method.

[0002] A vehicle comprises several transparent or translucent parts intended to transmit light. These include parts used for regulatory lighting purposes, for example those protecting the headlight units for the main and dipped beam headlights or the indicator lights. Furthermore, the vehicle may also have light sources intended for decorative purposes which improve the aesthetics of the vehicle.

[0003] For these purposes, it is possible to treat an external surface or an internal face of the transparent or translucent plastic parts in order to improve their appearance. One possibility for doing this is to overmould an opaque film or mask onto the external surface of the part, the opaque film having a predefined pattern allowing the passage of light. In this way, when the light source associated with the part emits light, the latter is partially blocked by the opacity of the opaque film and partially transmitted by the parts of the part which are opposite the pattern. This makes it possible to improve the aesthetics of the light beam transmitted, by the transparent or translucent part, from the light source to the external environment. An opaque film as described above can cause problems of colour matching with the paint of the other parts of the vehicle, which has a negative impact on the aesthetics of the vehicle.

[0004] It is also known to paint the external or internal face of a transparent or translucent body panel and then to remove a more or less significant part of the deposited layer of paint, for example by making microperforations or larger areas using a laser on the layer of paint in order to clear areas of any paint and make them transparent or translucent. The aim is to allow light to pass through from the rear of the body part.

[0005] In the case of microperforations, the latter are sized and distributed on the body panel so as to allow visible light emitted from an internal face of the body panel to pass towards the exterior of the body panel while not allowing, when the light source(s) are off, to see into the through the body panel from the exterior of the vehicle while maintaining an overall appearance close to a painted body part without removal of paint from the body part due to the small size of the microperforations.

[0006] The microperforations made using a laser are conventionally of substantially circular shape and the number of microperforations can be relatively large on a treated surface. Indeed, the areas capable of letting light pass can measure from a few centimeters to several tens of centimeters and the microperforations can have a size ranging from 20 to 1000 micrometers, preferably between 50 and 700 micrometers, preferably between 100 and 300 micrometers, and can be spaced from each other by a distance of between 1 and 4 times the size of the microperforations, preferably between 2 and 3 times the size of the microperforations, preferably substantially equal to 2 times the size of the microperforations. The production of circular microperforations in very large numbers has several disadvantages: - The cycle time per microperforation performed is quite long, this being due to the circular shape of the microperforations. Conventionally, this shape is obtained by making concentric circles with the laser, or by circular scanning of the contour of the circle with the laser and then scanning by rectilinear trajectories inside the defined contour. These two options lead to having a significant cycle time per microperforation.Given the large number of microperforations that can be made at the level of a panel to obtain the desired visual effect (taking into account the size of the microperforations and their spacing on a surface as described above), and which can be at least 4 microperforations per mm2, or 40,000 microperforations on a square surface with sides of 100 millimeters, the cycle time to obtain the final bodywork panel can be significant (the problem of the significant cycle time appearing when at least 5,000 to 10,000 microperforations are made, while knowing that one wishes to have a cycle time of less than 5 minutes, preferably between 1 and 2 minutes). - Programming the robot carrying the laser is quite complex, which leads to obtaining heavy programming files which are therefore difficult to process by the machine.

[0007] The invention aims in particular to remedy these problems by proposing a method making it possible to reduce the cycle time for producing microperforations, and therefore the cycle time for manufacturing the final decorated panel.

[0008] To this end, the invention relates to a method for manufacturing a motor vehicle body part comprising the following steps: - depositing at least one opaque coating on at least part of one face of a main body of the bodywork part, the main body being made of transparent or translucent plastic material, and - production of a set of microperforations of the opaque coating by removing the opaque coating using a laser beam locally irradiating the coating, an irradiation trajectory of the laser beam consisting solely of successive, substantially rectilinear trajectory lines.

[0009] The term "transparent" or "translucent" is understood to mean that a part is at least transparent or translucent to any light radiation having a wavelength included in the visible spectrum, i.e. between approximately 380 and 780 nm, or to any infrared radiation, i.e. with a wavelength between approximately 780 nm and 1 mm.

[0010] Microperforations are understood to mean the removal of the paint layer of a layer whose largest dimension of the irradiated surface is between 20 and 1000 pm, preferably between 50 and 700 pm, preferably between 100 and 300 pm.

[0011] “Local irradiation” means removal of material over the entire thickness of the coating. The coating may be a paint, for example in three layers (a primer 5 to 20 μm thick, a base 10 to 40 μm thick and a varnish 25 to 40 μm thick, i.e. a total thickness of between 40 and 100 μm), a metallization coating with a thickness that may be between 1 and 5 μm, a printed ink, a coating deposited by pad printing or screen printing, a film applied to the bodywork part (and comprising an ink, paint, etc.), etc. Laser irradiation makes it possible to remove the coating over its entire thickness (or the coating present on the film in the case of application of a film, the film acting as a support for the coating), for example in a thickness range of between 1 and 100 μm for the thickness examples above.

[0012] Thus, producing microperforations solely by irradiation trajectories comprising only substantially rectilinear trajectory lines allows a saving of time by simplifying the trajectory compared to a trajectory according to the prior art which is much more complex and mixes rectilinear and curved lines. In addition, the programming of a trajectory comprising only rectilinear movements is less complex to carry out and more easily processed by a machine than that according to the prior art.

[0013] According to other optional characteristics of the manufacturing process taken alone or in combination: - the irradiation trajectory comprises at least in part the repetition of the same pattern of trajectory lines composed of several successive, substantially rectilinear trajectory lines; - at least one trajectory line is composed of irradiation sections and non-irradiation sections of the opaque coating so as to allow at least part of several microperforations to be produced; - a focal distance between a source of emission of the laser beam and the face of the bodywork part is greater than or equal to between 100 and 1,000 millimeters, preferably between 300 and 700 millimeters, preferably between 400 and 600 millimeters; - the focal distance between the emission source of the laser beam and the face of the body part is modified within the irradiation path of the face of the body part; - at least a portion of the microperforations is substantially parallelogram-shaped, preferably substantially square or substantially rectangular in shape; - a width of a scanning band of the laser beam on the face of the bodywork part is between 40 and 200 pm, preferably between 70 and 120 pm, preferably substantially equal to 100 pm - the opaque coating is formed by at least one layer of paint, a printed ink, a metallization coating, a coating deposited by pad printing or by screen printing;

[0014] The invention also relates to a device for manufacturing a motor vehicle body part comprising: - at least one member for depositing at least one opaque coating on at least part of a face of a main body of the bodywork part, the main body being made of transparent or translucent plastic material, and - at least one source emitting a laser beam configured to produce a set of microperforations of the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, the source emitting the laser beam being configured to produce an irradiation trajectory of the laser beam consisting solely of lines of successive trajectories that are substantially rectilinear.

[0015] Advantageously, the laser beam emitting source is configured to vary the focal distance between the laser beam emitting source and the face of the bodywork part during the irradiation of the face of the bodywork part. Brief description of the figures

[0016] The invention will be better understood on reading the following description given solely by way of example and with reference to the appended drawings in which:

[0017] [Fig-1] is a view of a body panel comprising microperforations produced by a method according to the invention,

[0018] [Fig.2] is a view of a portion of an area comprising microperforations produced by a method according to the invention,

[0019] [Fig.3] is a representation of a microperforation made by a process according to a first embodiment of the invention,

[0020] [Fig.4] is a representation of a microperforation made by a process according to a second embodiment of the invention, and

[0021] [Fig.5] is a representation of a set of microperforations comparable to the microperforation of [Fig.4]. Detailed description

[0022] [Fig. 1] shows a bodywork part 2 comprising a transparent or translucent main body 3 and microperforation zones 4 produced by a method according to the invention, as well as [Fig. 2] illustrating a portion of a microperforation zone 4 comprising a set of microperforations (here second microperforations 10 as described below).

[0023] The body part 2 is, in the example illustrated in [Fig.l], a front bumper. Of course, it can also be any other body part, for example a tailgate, a grille, a rear bumper, etc. It could also be a part added to a body panel.

[0024] The bodywork part 2 of [Fig.l] comprises two microperforation zones. Of course, the number of microperforation zones 4 may be different, as may the size(s) of the microperforation zones 4. The microperforation zones 4 may be the same size or different sizes, comprise a greater or lesser number of microperforations, etc.

[0025] The microperforation zones 4 can be made on an external face 6 and / or on an internal face (not visible in [Fig.l]) of the bodywork part 2. The external face 6 is understood to mean the face of the bodywork part 2 visible from the outside of the vehicle when the bodywork part 2 is mounted on a vehicle. The internal face is understood to mean the face of the bodywork part 2 opposite the external face 36, and not visible from the outside of the vehicle when the bodywork part 2 is mounted on a vehicle.

[0026] The microperforations of a microperforation zone 4 are distributed at the level of the microperforation zone 4 ([Fig.2] illustrates three lines of five microperforations), have one or more different shapes, a transparency (or a translucency) allowing the radiation emitted by a source of visible light or infrared radiation and emitted from the rear of the bodywork part 2 (i.e. facing the internal face of the bodywork panel 2) to pass through, while not allowing the passage of light. through the body panel 2, in particular when a visible light source is inactive. As a reminder, the term "transparent", respectively "translucent", means that a part is at least transparent, respectively translucent, to any light radiation having a wavelength included in the visible spectrum, i.e. between approximately 380 and 780 nm, or to any infrared radiation, i.e. with a wavelength between approximately 780 nm and 1 mm. The visible light source is preferably an optical device comprising light-emitting diodes (LEDs). The infrared radiation source may be a LIDAR.

[0027] The bodywork part 2 is made using a material that is transparent or translucent to light, such as, by way of example and non-exclusively: - Polycarbonate (PC), - Polymethylmethacrylate (PMMA), - Acrylonitrile butadiene styrene (ABS) or styrene acrylonitrile (SAN), Acrylonitrile Styrene Acrylate (ASA) and their mixtures, - amorphous polyolefins such as cycloolefin copolymers (COC) or cycloolefin polymers (COP), - Polyethylene terephthalate (PET), - Polypropylene (PP), - Polyamide (PA), - Polybutylene terephthalate (PBT), - polyurethane (PU), and - Polyvinyl chloride (PVC).

[0028] The method for producing the bodywork part 2 (injection or thermoforming for example) or the dimensions and shapes of the bodywork part 2 are known to those skilled in the art and will not be the subject of a detailed description here.

[0029] The manufacturing method according to the invention comprises the following steps: - Deposition of at least one opaque coating on at least a portion of one face of the main body 3 of the bodywork part 2. This may for example be a paint (composed of a single layer or several layers), an ink, etc., as described previously. Generally speaking, this is a coating which does not allow visible light or infrared radiation emitted by the source placed behind the bodywork part 2 to pass through and from which it is possible to locally remove the layer(s) of opaque material by using a laser beam. This deposition may be carried out on the external face 6 or on the internal face of the bodywork part 2. - Creation of a set of microperforations of the opaque coating by removing the opaque coating using a locally irradiating laser beam the opaque coating, an irradiation path of the laser beam consisting solely of successive substantially rectilinear path lines. In the context of the invention, a laser beam irradiates a portion of the opaque coating to effect a total removal, in the thickness (according to the definition provided previously), of the opaque coating at the level of the zone(s) 4 of microperforations of the latter in order to obtain transparent or translucent microperforations as described above. This removal of the opaque coating makes it possible to uncover the main body 3, itself transparent or translucent. Visible light or infrared radiation will therefore be able to pass through the bodywork part 2, here the bodywork panel 2, at the level of the microperforations.

[0030] The sizes of the microperforations and their arrangement relative to each other (for example the distance between two adjacent microperforations) are chosen so as to obtain the desired effect described above, namely to allow the emitted radiation to pass through without seeing through the bodywork part 2 from the outside, in particular when a visible light source is switched off. The source of the laser beam is configured to obtain microperforations of the desired shape(s) and size(s), the desired spacing between the microperforations or even a desired transparency at the microperforations. The parameters set are in particular the following: - The focal distance between the laser beam source and the body part 2. - The power of the laser beam. - The scanning speed of the 4 microperforation zones. - The exposure time of an area to be irradiated using a laser beam. - The overlap or not of trajectory lines, as well as the percentage of overlap between trajectory lines. - The alternation or not of trajectory lines corresponding to irradiation or not, or the presence within the same trajectory line of irradiation and non-irradiation sections. - The frequency of the laser when the laser is a pulsed laser. - The wavelength of the laser source.

[0031] Figures 3 and 4 illustrate two microperforations 8 and 10 of different shapes. [Fig. 3] illustrates a first microperforation 8 according to a first embodiment of the invention, here of any shape. A first trajectory 12, comprising only first trajectory lines 12' (two referenced in [Fig. 3]) which are substantially rectilinear, makes it possible to obtain the first microperforation 8. The first trajectory 12 is made up of several first trajectory lines 12' which may or may not be similar and which make it possible to obtain a first irradiated surface. 14, forming the first microperforation 8.

[0032] [Fig. 4] illustrates a second microperforation 10 according to a second embodiment of the invention. A second trajectory 16, comprising only substantially rectilinear second trajectory lines 16' (two referenced in [Fig. 4]), makes it possible to obtain the second microperforation 10. The second trajectory 16 is made up of several trajectory lines having substantially identical and aligned sections in order to obtain a second irradiated zone 18 of rectangular shape. According to the second embodiment of the invention, the irradiation trajectory (here the second irradiation trajectory 16) comprises at least in part the repetition of the same pattern 20 of trajectory lines composed of several successive rectilinear trajectory lines (here the second trajectory lines 16') (two successive patterns 20 are referenced in [Fig. 1]).Repeating the same pattern makes it even easier to program the movements of the laser beam source.

[0033] [Fig. 5] illustrates a set of second microperforations 10 forming two groups of aligned second microperforations 10. Together, these eight perforations 10 form at least a portion of a microperforation zone 4. In this example, a third trajectory line 22 makes it possible to produce an entire line of second microperforations 10. Of course, the number of trajectories for producing a set of microperforations can vary. It would be possible, for example, to produce all the microperforations illustrated in [Fig. 5] via a single trajectory.

[0034] The third trajectory 22 is composed, like the first and second trajectories 12 and 16, of third rectilinear trajectory lines 22'. However, at least a portion of the third trajectory lines 22' (the horizontal trajectory lines in [Fig. 4]) comprises irradiation sections 24' and non-irradiation sections 24”. In this embodiment, the alternation of irradiation sections 24' and non-irradiation sections 24” allows at least one third trajectory line 22' (the horizontal trajectory lines in [Fig. 4]) to allow at least a portion of several second microperforations 10 to be produced. In the example of [Fig. 4], all the third horizontal trajectory lines 22' participate in producing the second microperforations 10 of the same group of microperforations by alternating the irradiation sections 24' and non-irradiation sections 24”.An alignment of at least a portion of the second microperforations 10 makes it easier to pool the production of said microperforations.

[0035] Preferably, the focal distance between a source of emission of the laser beam and the face of the bodywork part is between 100 and 1000 millimeters, preferably between 300 and 700 millimeters, preferably between 400 and 600 millimeters. The implementation of a high focal length makes it possible to obtain a point of impact of the laser beam on the body part 2 of larger dimensions, and therefore to limit the number and / or the amplitude of movements of the laser beam to be implemented to make one or more microperforations. A long focal length also makes it possible to scan a larger area of ​​the body part 2 by simple movements of the lens(es) of the laser source without having to move the source of the laser beam too often from one area to be scanned to another (movement necessary when the source of the laser beam reaches its spatial limit for treating an area of ​​the body part 2 by simple movements of the lens). An angular movement of the laser beam is therefore preferred while a member carrying the source of the laser beam, for example a robot arm, is fixed.This limits the movements of the said carrier organ by increasing the surface area that can be irradiated by simply moving the lens of the laser beam source. It is even possible to reduce the number of laser beam sources to be used to treat a given surface within a given time limit that must be respected.

[0036] It is possible to make a shape of microperforations easily achievable by a trajectory according to the invention, and this in order to further reduce the manufacturing time of the bodywork part 2. At least a portion of the microperforations has a shape of which at least one side is parallel to a trajectory line. This is the case for the microperforations of Figures 2 to 5. Preferably, at least a portion of the microperforations are substantially parallelogram-shaped, preferably square or substantially rectangular. These are very simple shapes to produce by a method according to the invention, as demonstrated by the simple irradiation trajectories in Figures 3 and 4. As explained previously, it may be advantageous to have a point of impact of the laser beam on the face of the bodywork part that is quite large for the reasons mentioned above (increasing the size of an irradiated surface by simple angular movements of the lens).More generally, it is interesting to determine a size of the impact point allowing to optimize the scanning of an area to be irradiated, while ensuring a size allowing to produce microperforations of the desired shape, while respecting the irradiation speeds, the irradiation times or even the overlap between two irradiation trajectory lines. To do this, the width of a scanning band of the laser beam on the face of the bodywork part is between 40 and 200 pm, preferably between 70 and 120 pm, preferably substantially equal to 100 pm.

[0037] The invention also relates to a device for manufacturing a vehicle part comprising: - At least one member for depositing at least one opaque coating on at least one part of a face of a main body 3 of the bodywork part 2, the main body 3 being made of transparent or translucent plastic material. It may be a paint application robot, or even means for depositing an opaque film. - At least one source emitting a laser beam configured to produce a set of microperforations of the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, the source emitting the laser beam being configured to produce an irradiation trajectory of the laser beam consisting solely of lines of successive trajectories that are substantially rectilinear.

[0038] Advantageously, the emitting source of the laser beam is configured to be able to vary the focal distance between the emitting source of the laser beam and the face of the bodywork part 2 during the irradiation of the face of the bodywork part 2, and this for reasons mentioned above. List of references

[0039] 2: body part

[0040] 3: main body 4: microperforation zones 6: external face

[0041] 8: first microperforation

[0042] 10: second microperforation

[0043] 12: first trajectory

[0044] 12': first trajectory lines

[0045] 14: first irradiated surface

[0046] 16: second trajectory

[0047] 16': second trajectory lines

[0048] 18: second irradiated surface

[0049] 20: trajectory line patterns

[0050] 22: third trajectory

[0051] 22': third trajectory lines

[0052] 24': irradiation sections

[0053] 24”: non-irradiation sections

Claims

Claims

1. Method for manufacturing a bodywork part (2) of a motor vehicle, characterized in that it comprises the following steps: - depositing at least one opaque coating on at least a portion of a face (6) of a main body (3) of the bodywork part (2), the main body (3) being made of transparent or translucent plastic material, and - producing a set of microperforations (8, 10) of the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, an irradiation path (12, 16, 22) of the laser beam consisting solely of successive path lines (12', 16', 22') that are substantially rectilinear.

2. Manufacturing method according to claim 1, in which the irradiation trajectory (12, 16, 22) comprises at least in part the repetition of the same pattern of trajectory lines (20) composed of several successive trajectory lines (16') which are substantially rectilinear.

3. Manufacturing method according to any one of the preceding claims, in which at least one trajectory line (22') is composed of irradiation sections (24') and non-irradiation sections (24”) of the opaque coating so as to allow at least part of several microperforations (10) to be produced.

4. Manufacturing method according to any one of the preceding claims, wherein a focal distance between a source of emission of the laser beam and the face (6) of the bodywork part (2) is greater than or equal to between 100 and 1000 millimeters, preferably between 300 and 700 millimeters, preferably between 400 and 600 millimeters.

5. A manufacturing method according to any one of the preceding claims, wherein the focal distance between the emission source of the laser beam and the face (6) of the bodywork part (2) is modified within the irradiation path (12, 16, 22) of the face (6) of the bodywork part (2).

6. A manufacturing method according to any one of the preceding claims, wherein at least a portion of the microperforations (8, 10) are substantially parallelogram-shaped, preferably substantially square or substantially rectangular in shape.

7. A manufacturing method according to any one of the preceding claims, wherein a width of a scanning band of the laser beam on the face of the bodywork part is between 40 and 200 pm, preferably between 70 and 120 pm, preferably substantially equal to 100 pm.

8. A manufacturing method according to any one of the preceding claims, wherein the opaque coating is formed by at least one layer of paint, a printed ink, a metallization coating, a coating deposited by pad printing or by screen printing.

9. Device for manufacturing a motor vehicle body part comprising: - At least one member for depositing at least one opaque coating on at least a portion of a face (6) of a main body (3) of the body part (2), the main body (3) being made of transparent or translucent plastic material, and - At least one source emitting a laser beam configured to produce a set of microperforations of the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, the source emitting the laser beam being configured to produce an irradiation trajectory (12, 16, 22) of the laser beam consisting solely of successive substantially rectilinear trajectory lines (12', 16', 22').

10. Manufacturing device according to the preceding claim, in which the emitting source of the laser beam is configured to vary the focal distance between the emitting source of the laser beam and the face (6) of the bodywork part (2) during the irradiation of the face (6) of the bodywork part (2).

Images