Manufacturing process for a transparent or translucent vehicle part

Abstract

The invention relates to a method for manufacturing a motor vehicle body part (2), characterized in that it comprises the following steps: - deposition of 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, and - creation of a series of micro-perforations (8, 10) in 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 straight path lines (12', 16', 22'). 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 that contributes to the exterior appearance of the vehicle, and a device for carrying out such a method.

[0002] A vehicle includes several transparent or translucent parts designed to transmit light. These include parts used for regulatory lighting purposes, for example, 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 an external surface or an internal face of transparent or translucent plastic parts to improve their appearance. One way to do this is to overmold an opaque film or mask onto the external surface of the part. The opaque film has a predefined pattern that allows light to pass through. In this way, when the light source associated with the part emits light, the light is partially blocked by the opacity of the opaque film and partially transmitted through the parts of the part facing the pattern. This improves the aesthetics of the light beam transmitted from the light source to the external environment through the transparent or translucent part. An opaque film such as the one described above can cause color matching problems with the paint on other parts of the vehicle, which negatively impacts the vehicle's aesthetics.

[0004] It is also known to paint the external or internal surface of a body panel transparent or translucent and then remove a more or less significant portion of the paint layer, for example by creating micro-perforations or larger areas using a laser in the paint layer in order to expose areas of paint and make them transparent or translucent. The aim is to allow light to pass through from the rear of the body panel.

[0005] In the case of micro-perforations, these are sized and distributed on the body panel so as to allow visible light emitted from an inner face of the body panel to pass through to the outside of the body panel, while not allowing visibility when the light source(s) are switched off. through the body panel from outside the vehicle while maintaining an overall appearance close to a painted body part without removing paint from the body part due to the small size of the micro-perforations.

[0006] Microperforations made using a laser are typically substantially circular in shape, and the number of microperforations can be relatively large on a treated surface. Indeed, the areas capable of transmitting light can measure from a few centimeters to several tens of centimeters, and the microperforations can range in size from 20 to 1000 micrometers, preferably between 50 and 700 micrometers, preferably between 100 and 300 micrometers, and can be spaced from each other at 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 approximately equal to twice the size of the microperforations. Making a very large number of circular microperforations presents several drawbacks: The cycle time per micro-perforation is quite long, due to the circular shape of the micro-perforations. Typically, this shape is achieved by creating concentric circles with the laser, or by scanning the circular outline with the laser and then scanning with straight trajectories inside the defined contour. Both of these options result in a significant cycle time per micro-perforation.Given the large number of micro-perforations that can be made on a panel to achieve the desired visual effect (considering the size of the micro-perforations and their spacing on a surface as described above), and which can be at least 4 micro-perforations per mm2, i.e. 40,000 micro-perforations on a square surface of 100 millimeters on each side, the cycle time to obtain the final body panel can be significant (the problem of significant cycle time arises when making at least 5,000 to 10,000 micro-perforations, while knowing that we want 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 large programming files that are therefore difficult for the machine to process.

[0007] The invention aims in particular to remedy these problems by proposing a process to reduce the cycle time for making micro-perforations, and therefore the cycle time for manufacturing the final decorated panel.

[0008] To this end, the invention relates to a method for manufacturing a body part for a motor vehicle comprising the following steps: - application of at least one opaque coating to at least part of a face of a main body part, the main body being made of transparent or translucent plastic material, and - creation of a set of micro-perforations in 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 straight trajectory lines.

[0009] The term “transparent” or “translucent” means that a part is at least transparent or translucent to any light radiation with a wavelength 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 from a surface where the 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" refers to the removal of material through 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 coat 10 to 40 µm thick, and a clear coat 25 to 40 µm thick, for a total thickness between 40 and 100 µm), a metallization coating with a thickness between 1 and 5 µm, a printed ink, a coating applied by pad printing or screen printing, a film applied to the bodywork (including ink, paint, etc.), etc. Laser irradiation makes it possible to remove the coating through its entire thickness (or the coating present on the film in the case of a film application, the film acting as a substrate for the coating), for example, in a thickness range between 1 and 100 µm for the thickness examples above.

[0012] Thus, creating micro-perforations using only irradiation trajectories consisting solely of substantially straight lines saves time by simplifying the trajectory compared to a prior art trajectory, which is far more complex and mixes straight and curved lines. Furthermore, programming a trajectory consisting only of straight movements is less complex and more easily processed by a machine than programming a prior art trajectory.

[0013] Depending on other optional features of the manufacturing process taken alone or in combination: - the irradiation trajectory includes at least in part the repetition of the same pattern of trajectory lines composed of several successive, substantially straight trajectory lines; - at least one trajectory line is composed of irradiation sections and non-irradiation sections of the opaque coating so as to allow the creation of at least part of several micro-perforations; - a focal distance between a laser beam emission source and the face of the body 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 laser beam emission source and the face of the body part is modified within the irradiation trajectory of the face of the body part; - at least part of the micro-perforations are substantially parallelogram-shaped, preferably substantially square or substantially rectangular; - the width of a laser beam scan band on the face of the body part is between 40 and 200 µm, preferably between 70 and 120 µm, preferably substantially equal to 100 µm - the opaque coating is formed by at least one layer of paint, printed ink, metallization coating, coating deposited by pad printing or screen printing;

[0014] The invention also relates to a device for manufacturing a motor vehicle body part comprising: - at least one deposition device for at least one opaque coating on at least part of a face of a main body of the bodywork component, the main body being made of transparent or translucent plastic material, and - at least one laser beam emitting source configured to perform a set of micro-perforations in the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, the laser beam emitting source being configured to perform a laser beam irradiation path consisting solely of substantially straight successive path lines.

[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 body part during the irradiation of the face of the body part. Brief description of the figures

[0016] 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:

[0017] [Fig. 1] is a view of a body panel comprising micro-perforations made by a process according to the invention,

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

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

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

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

[0022] Figure 1 shows a body part 2 comprising a transparent or translucent main body 3 and micro-perforation zones 4 produced by a process according to the invention, as well as Figure 2 illustrating a portion of a micro-perforation zone 4 comprising a set of micro-perforations (here, second micro-perforations 10 as described later).

[0023] Body part 2 is, in the example illustrated in [Fig. 1], a front bumper. Of course, it could also be any other body part, for example a tailgate, a grille, a rear bumper, etc. It could also be a part attached to a body panel.

[0024] The body part 2 of [Fig. 1] comprises two micro-perforation zones. Of course, the number of micro-perforation zones 4 can vary, as can their size(s). The micro-perforation zones 4 may be the same size or different sizes, comprise a greater or lesser number of micro-perforations, etc.

[0025] The micro-perforation zones 4 can be made on an external face 6 and / or on an internal face (not visible in [Fig. 1]) of the body part 2. The external face 6 is understood to be the face of the body part 2 visible from outside the vehicle when the body part 2 is mounted on a vehicle. The internal face is understood to be the face of the body part 2 opposite the external face 36, and not visible from outside the vehicle when the body part 2 is mounted on a vehicle.

[0026] The microperforations of a zone 4 of microperforations are distributed at the level of zone 4 of microperforations (Fig. 2 illustrates three lines of five microperforations), have different shapes, and a transparency (or translucency) allowing the passage of radiation emitted by a visible light source or infrared radiation emitted from the rear of the part. body panel 2 (i.e., facing the inner face of body panel 2), while preventing visibility through body panel 2, particularly when a visible light source is inactive. As a reminder, "transparent" or "translucent" means that a part is at least transparent or translucent to any light radiation with a wavelength 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 can 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 without limitation: - Polycarbonate (PC), - Polymethyl methacrylate (PMMA), - of acrylonite butadiene styrene (ABS) or styrene acrilonitrile (SAN), acrilonitrile styrene acrylate (ASA) and their mixtures, - amorphous polyolefins such as copolymer cyclo-olefins (COC) or polymer cyclo-olefins (COP), - Polyethylene terephthalate (PET), - Polypropylene (PP), - Polyamide (PA), - Polybutylene terephthalate (PBT), - polyurethane (PU), and - Polyvinyl chloride (PVC).

[0028] The process for manufacturing the body part 2 (injection or thermoforming for example) or the dimensions and shapes of the body part 2 are known to those skilled in the art and will not be described in detail here.

[0029] The manufacturing process according to the invention comprises the following steps: - Application of at least one opaque coating to at least part of one face of the main body 3 of the body part 2. This could be, for example, paint (composed of a single layer or several layers), ink, etc., as described previously. Generally, it is a coating that does not allow visible light or infrared radiation emitted by the source located behind the body part 2 to pass through, and from which the layer(s) of opaque material can be locally removed using a laser beam. This application can be carried out on the external face 6 or on the internal face of the body part 2. - Creation of a series of micro-perforations in the opaque coating by removing the opaque coating using a laser beam that locally irradiates the opaque coating. The laser beam irradiation path consists solely of successive, substantially straight lines. In the context of this invention, a laser beam irradiates a portion of the opaque coating to completely remove it through its thickness (as defined above) at the level of the micro-perforation zone(s) 4, thereby obtaining transparent or translucent micro-perforations as described above. This removal of the opaque coating exposes the main body 3, which is itself transparent or translucent. Visible light or infrared radiation can then pass through the bodywork component 2, in this case, the bodywork panel 2, at the level of the micro-perforations.

[0030] The size of the microperforations and their arrangement relative to each other (for example, the distance between two adjacent microperforations) are chosen to achieve the desired effect described above, namely, to allow the emitted radiation to pass through without preventing visibility through the bodywork part 2 from the outside, particularly when a visible light source is switched off. The laser beam source is configured to obtain microperforations of the desired shape(s) and size(s), the desired spacing between the microperforations, and the desired transparency at the microperforations. The parameters set include, in particular, the following: - The focal distance between the laser beam source and the bodywork part 2. - The power of the laser beam. - The scanning speed of the 4 micro-perforation zones. - The exposure time of an area to be irradiated using a laser beam. - Whether or not trajectory lines overlap, 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 segments. - 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 micro-perforations 8 and 10 of different shapes. Figure 3 illustrates a first micro-perforation 8 according to a first embodiment of the invention, here of arbitrary shape. A first trajectory 12, not including that first lines of trajectories 12' (two referenced on the [Fig.3]) substantially straight, allows obtaining the first microperforation 8. The first trajectory 12 is made up of several first lines of trajectories 12' which may be similar or not and which allow obtaining a first irradiated surface 14, forming the first microperforation 8.

[0032] Figure 4 illustrates a second micro-perforation 10 according to a second embodiment of the invention. A second trajectory 16, comprising only second trajectory lines 16' (two referenced in Figure 4) that are substantially straight, provides the second micro-perforation 10. The second trajectory 16 consists of several trajectory lines having substantially identical and aligned segments to obtain a second irradiated area 18 of rectangular shape. According to the second embodiment of the invention, the irradiation trajectory (here the second irradiation trajectory 16) includes at least part of the repetition of the same pattern 20 of trajectory lines composed of several successive straight trajectory lines (here the second trajectory lines 16') (two successive patterns 20 are referenced in Figure 1).Repeating the same pattern makes it even easier to program the movements of the laser beam source.

[0033] Figure 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 create an entire line of second microperforations 10. Of course, the number of trajectories required to create a set of microperforations can vary. For example, it would be possible to create all the microperforations illustrated in Figure 5 using a single trajectory.

[0034] The third trajectory 22 is composed, like the first and second trajectories 12 and 16, of third lines of straight trajectories 22'. However, at least part of the third trajectory lines 22' (the horizontal trajectory lines in [Fig. 4]) includes irradiation segments 24' and non-irradiation segments 24”. In this embodiment, the alternation of irradiation segments 24' and non-irradiation segments 24” ensures that at least one third trajectory line 22' (the horizontal trajectory lines in [Fig. 4]) allows for the creation of at least part of several secondary microperforations 10. In the example of [Fig. 4], all the horizontal third trajectory lines 22' participate in the creation of the secondary microperforations 10 of the same group of microperforations by alternating the irradiation segments 24' and non-irradiation segments 24”. An alignment at least part of the second micro-perforations 10 makes it possible to facilitate the pooling of the production of said micro-perforations.

[0035] Preferably, the focal distance between a laser beam emission source and the face of the bodywork part is between 100 and 1,000 millimeters, preferably between 300 and 700 millimeters, and preferably between 400 and 600 millimeters. Using a high focal length allows for a larger laser beam impact point on the bodywork part 2, thus limiting the number and / or amplitude of laser beam movements required to create one or more micro-perforations.A long focal length also allows for scanning a larger area of ​​the bodywork part 2 with simple movements of the laser source lens(es), without having to frequently move the laser beam source from one area to another (a movement necessary when the laser beam source reaches its spatial limit for treating an area of ​​the bodywork part 2 with simple lens movements). Therefore, an angular movement of the laser beam is preferred, while a component carrying the laser beam source, for example, a robot arm, remains fixed. This limits the movement of the carrying component by increasing the area that can be irradiated by simply moving the laser beam source lens. It is even possible to reduce the number of laser beam sources required to treat a given surface within a specified timeframe.

[0036] It is possible to create a micro-perforation pattern easily achievable by a trajectory according to the invention, thereby further reducing the manufacturing time of the body part 2. At least some of the micro-perforations have a shape in which at least one side is parallel to a trajectory line. This is the case for the micro-perforations in Figures 2 to 5. Preferably, at least some of the micro-perforations are substantially parallelogram-shaped, preferably square or substantially rectangular. These are very simple shapes to produce by a process according to the invention, as demonstrated by the simple irradiation trajectories in Figures 3 and 4. As explained previously, it can be advantageous to have a relatively large laser beam impact point on the face of the body part for the reasons mentioned above (increasing the size of an irradiated surface by simple angular movements of the lens).More generally, it is important to determine an impact point size that optimizes the scanning of an area to be irradiated, while ensuring a size that allows for the creation of micro-perforations of the desired shape, respecting irradiation speeds, irradiation times, and the overlap between two irradiation path lines. To achieve this, the width of a laser beam scan band on the... 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 device for depositing at least one opaque coating on at least part of a face of a main body 3 of the bodywork component 2, the main body 3 being made of transparent or translucent plastic. This may be a paint application robot, or means for depositing an opaque film. - At least one laser beam emitting source configured to perform a set of micro-perforations in the opaque coating by removing the opaque coating using a laser beam locally irradiating the opaque coating, the laser beam emitting source being configured to perform a laser beam irradiation path consisting solely of substantially straight successive path lines.

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

[0039] 2: body part

[0040] 3: main body 4: Micro-perforation zones 6: outer face

[0041] 8: first micro-perforation

[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 lines of trajectory

[0052] 24': irradiation sections

[0053] 24”: non-irradiation sections

Claims

Demands

1. A method for manufacturing a motor vehicle body part (2) characterized in that it comprises the following steps: - deposition of at least one opaque coating on at least a part 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 - making a set of micro-perforations (8, 10) of the opaque coating by removing the opaque coating with a laser beam locally irradiating the opaque coating, each micro-perforation forming a removal of the opaque coating whose largest dimension is between 20 and 1,000 pm, preferably between 50 and 700 pm, preferably between 100 and 300 pm, an irradiation path (12, 16, 22) of the laser beam being made up solely of successive substantially rectilinear path lines (12', 16', 22').

2. A manufacturing method according to claim 1, wherein the irradiation trajectory (12, 16, 22) includes at least in part the repetition of the same pattern of trajectory lines (20) composed of several successive substantially straight trajectory lines (16').

3. A manufacturing method according to any one of the preceding claims, wherein 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 the creation of at least a part of several micro-perforations (10).

4. A manufacturing method according to any one of the preceding claims, wherein a focal distance between a laser beam emission source and the face (6) of the body part (2) is greater than or equal to between 100 and 1,000 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 laser beam emission source and the face (6) of the body part (2) is modified within the irradiation trajectory (12, 16, 22) of the face (6) of the body part (2).

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

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

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, printed ink, metallization coating, pad-printed coating or screen-printed coating.

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