Method for producing a cover panel

Abstract

A method for producing a cover panel (2; 2'), wherein the cover panel (2; 2') has a base body (4) in which at least one ornament (6, 26) is introduced on a first side (10), wherein the at least one ornament (6, 26) is formed as a depression opposite a surface (36) of the first side (10), wherein the base body (4) is coated with a lacquer layer (14), wherein for applying the lacquer layer (14), a transfer lacquer film (44) is applied to the base body (4) such that the transfer lacquer film (44) spans the at least one ornament (6, 26), wherein the at least one ornament (6, 26) is cut free after the application of the transfer lacquer film (44), wherein the transfer lacquer film (44) comprises the lacquer layer (14) and a plastic film as a carrier (46), and the carrier (46) is cut free after the application of the transfer lacquer film (44) to the base body (4) is peeled off to expose the lacquer layer (14), whereby the cutting takes place,before the carrier (46) of the transfer varnish film (44) is removed to expose the varnish layer (14).

Description

[0001] A method for producing a cover panel, in particular as a body component of a motor vehicle, is described.

[0002] Methods for producing a cover panel of the type mentioned above are known in the prior art.

[0003] Motor vehicles with internal combustion engines produce waste heat during operation, which must be dissipated to maintain thermal stability. For this purpose, such internal combustion engines are typically water- or air-cooled. The excess heat energy is directed to large cooling surfaces and then dissipated by the airstream or by fans.

[0004] The front end of motor vehicles with internal combustion engines, especially those with the internal combustion engines located in front of a driver's cab (front-mounted engines), therefore generally features large ventilation openings at the front end of the vehicle. These ventilation openings are typically protected by a grille or louvre structure. A corresponding radiator is typically located behind such a grille or louvre structure.

[0005] Large cooling vents are generally no longer necessary in electric vehicles. Electric motors produce less waste heat.

[0006] Vehicle fronts can therefore be designed differently. However, more modern, more efficient combustion engines also require less cooling, so vehicle fronts can be designed differently and smaller cooling openings must be provided. This means that larger surfaces must be designed as closed ones.

[0007] The number of driver assistance systems in motor vehicles is constantly increasing. Driver assistance systems generally require sensors to provide the necessary input variables to be monitored and / or controlled. Outward-facing sensors are particularly necessary if the driver assistance systems are to monitor the vehicle's surroundings. Therefore, it is known to provide sensors in the area of the front of a vehicle that can monitor the surroundings, in particular the traffic ahead. Such sensors can include, for example, radar sensors, lidar sensors, cameras, or ultrasonic sensors.

[0008] This opens up new possibilities for the design and cladding of a vehicle's front end, but also presents challenges, particularly due to the high mechanical stress to which the front of a vehicle is exposed, for example, due to stone chips, insects, and other abrasive substances. Furthermore, the aforementioned sensors should be integrated as effectively as possible. The design possibilities, in particular, allow for the provision of larger panels and other new design elements.

[0009] From WO 2019 / 076859 A1 a front panel assembly for an electric vehicle is known, the assembly comprising an at least partially optically transparent laminate film with side edges, which comprises an optically transparent thermoplastic substrate and at least one protective layer, and a spacer structure having a base and a peripheral upright wall extending from the base, wherein the upright wall is connected to the laminate at at least a part of the side edges of the laminate, so that a space is created and enclosed between the laminate film and the spacer structure, and wherein the at least one protective layer of the laminate faces away from the spacer structure.

[0010] DE 41 34 271 C1 discloses a method for decorating or inscribing a surface by means of laser radiation, wherein the surface has at least two differently colored color lacquer layers, of which a first lacquer layer is transferred from a carrier to the surface in a transfer process and then a second lacquer layer is applied, which is removed in regions by means of laser radiation to produce the decoration or inscribing and thus exposes the underlying first lacquer layer.

[0011] The object is to further develop methods for producing a cover panel of the type mentioned at the outset so that a cover panel with a high-quality appearance can be produced.

[0012] The object is achieved by a method for producing a cover panel according to claim 1. Further embodiments and developments are the subject of the dependent claims.

[0013] A method for producing a cover panel is described, wherein the cover panel has a base body in which at least one ornament is introduced on a first side, wherein the at least one ornament is designed as a depression opposite a surface of the first side, wherein the base body is coated with a lacquer layer, wherein for applying the lacquer layer a transfer lacquer film is applied to the base body so that the transfer lacquer film spans the at least one ornament, wherein the at least one ornament is cut free after the transfer lacquer film has been applied.

[0014] In some designs, the lacquer layer primarily serves to conceal technical components located behind the lacquer layer, creating a high-quality appearance for the cover panel. This makes it possible to arrange fastening elements or other components behind the lacquer layer, invisible from the outside.

[0015] The coating layer preferably comprises conventional color pigments and a matrix of a conventional binder. The color pigments can be organic and / or inorganic pigments.

[0016] In preferred embodiments, the paint layer can be an opaque layer. The opaque layer blocks light in the visible wavelength range. The opaque layer can have various colors. Thus, the opaque layer can be adapted to the color scheme of the motor vehicle equipped with the corresponding cover panel.

[0017] It is also possible to make the base body transparent, allowing it to be used unchanged in various configurations. This reduces the number of component variants and thus the logistical effort and, consequently, the associated costs.

[0018] The ornament represents a recess opposite the surface of the cover panel. The first side can be an inner side with respect to the motor vehicle, so that the outer or visible side of the base body represents a smooth surface. The surface of the cover panel can be curved, for example, to enable an aerodynamic contour in the front area of a corresponding motor vehicle. However, a corresponding cover panel can also be used in a side or rear area and can also have a curved contour there. Applications in the passenger compartment of the motor vehicle are also conceivable.

[0019] Particularly preferably, the at least one ornament is at least one star-shaped depression.

[0020] Such ornamentation can fulfill a technical and / or design function, for example, by creating visible structures through light refraction and reflection. Especially when the visible surface of the base body is smooth, the structures appear embedded, which creates a particularly high-quality and aesthetically pleasing appearance.

[0021] Especially, but not exclusively, when a sensor is to be placed behind the ornament, it is important that the technical function of the corresponding sensor is not compromised. Depending on the sensor and layer material used, this could occur due to the opaque layer or due to a contour or layer thickness differences in the layer material. Therefore, with such sensors, it is advisable to keep an area in front of the sensor, in this case the ornament, free of the opaque layer.

[0022] Furthermore, the coating in the area of the ornament may be unclean, especially if it is applied as a foil.

[0023] The application of a lacquer layer using a transfer lacquer film is a technology described, for example, in WO 2010 / 094425 A2 or WO 2014 / 108335 A1. To produce a transfer lacquer film, a lacquer layer is formed on a carrier, in particular a carrier film. To apply the lacquer layer, the transfer lacquer film can be pressed, with the lacquer layer first, against a component to be coated—here, the base body—i.e., brought into contact with the base body so that the lacquer layer adheres to the base body. The carrier can then be removed, leaving the lacquer layer on the component. This is exactly how the application is carried out according to the present invention.

[0024] The transfer varnish film can be designed to be sufficiently stiff in terms of its elastic properties to allow it to be stretched over an ornament without sinking far enough into the ornament(s) to create contact between the varnish layer and the ornamental base.

[0025] Before applying the coating layer to the component, in preferred embodiments, the transfer coating film can be coated with a layer of an adhesion-promoting compound on the coating side. Alternatively or additionally, it is also possible to coat the component to be coated, in this case the base body, with such a compound before application. The adhesion-promoting compound can be UV-curing or thermally curing, for example.

[0026] Applying the lacquer layer using the transfer lacquer film ensures that the surface of the first side is lacquered without the lacquer adhering to a recess formed by the at least one ornament. By cutting out the transfer lacquer in the area of the ornament and removing it, the lacquer layer can be applied around the ornament(s), leaving the ornament(s) themselves unmarked.

[0027] In certain configurations, it is possible to produce the transfer varnish film as a web and unwind it into a roll. The roll can then be transported and cut to size and inserted on-site during the cover panel production process. Application can be performed by lamination.

[0028] Using the transfer varnish process, it is possible to achieve a high-quality surface finish for an ornamental cover panel with low energy consumption.

[0029] In principle, the transfer varnish film's backing can be removed immediately after application, exposing the varnish layer. When cutting out at least one ornament, the preferred laser only needs to penetrate the varnish layer. Cut-off areas of the varnish layer can then be removed.

[0030] However, it's advantageous to initially leave the carrier on the varnish layer. In this case, cutting through not only the varnish layer but also the carrier is severed. Cut-off sections of the transfer varnish film can then be removed.

[0031] In a further embodiment, it can be provided that the transfer lacquer film is applied with a flexible membrane, wherein the flexible membrane serves to press the transfer lacquer film on, and wherein the transfer lacquer film remains dimensionally stable when pressed on such that it does not stretch to a base of the at least one ornament.

[0032] For this purpose, the carrier of the transfer varnish film is preferably a plastic film with a uniform thickness between 30 and 300 µm, in particular between 100 and 150 µm, in particular 120 µm. After drying, the carrier can be punched or cut with a plotter, among other things. The carrier can be made of a non-polar plastic, in particular from the group of polypropylenes or phenolic resins.

[0033] The lacquer layer on the carrier preferably has a uniform layer thickness in the range of 8-28 µm, in particular 15-19 µm. The lacquer layer can be based on a plastic dispersion, in particular polyurethane, polyethylene, or polycarbonate.

[0034] In a further further embodiment, it can be provided that the pressing of the transfer varnish film onto the base body is carried out in a negative pressure atmosphere.

[0035] By pressing in a negative pressure atmosphere, it is possible to achieve higher coating quality and lower waste, as distortions in the paint layer caused by air bubbles are less likely.

[0036] In another further embodiment, it can be provided that the free cutting is carried out using a laser that moves along an ornamental edge of the ornament.

[0037] The laser is able to precisely trace a contour of the lacquer layer and cut the lacquer layer precisely at the edges of the ornament, i.e. the transition from the ornament to the surface.

[0038] In a further embodiment, it can be provided that the laser is guided parallel to a surface normal of the base body.

[0039] By guiding the laser parallel to a surface normal of the base body, it is possible to create clean edges that leave a high-quality impression.

[0040] In a further further embodiment, it can be provided that a position of the at least one ornament is detected by means of an optical detection device and that the laser and cover panel are positioned and moved relative to one another on the basis of the position determined by means of the optical detection device.

[0041] In one variant, it is possible to move the laser relative to the statically fixed cover panel. In another variant, it is possible to move the cover panel relative to the statically fixed laser. In a third variant, both the laser and the cover panel can be moved relative to the surroundings and relative to each other. Using the optical detection device, it is possible to precisely detect the position of at least one ornament. This avoids the laborious positioning of the cover panel relative to the laser.

[0042] In a further further embodiment, it can be provided that the ornament is introduced into the base body by primary shaping, forming or machining processes.

[0043] Appropriate machining processes can include milling, for example.

[0044] In a further further embodiment, it can be provided that the paint layer comprises soot as the only pigment.

[0045] The use of soot is particularly suitable in conjunction with the use of lasers, as soot layers can be easily separated using the laser.

[0046] In a further further embodiment, it can be provided that the cut-off transfer varnish film and / or the cut-off varnish layer is vacuumed off.

[0047] By vacuuming the cut-off transfer varnish film and / or the cut-off varnish layer, mechanical contact of objects with the cover panel can be avoided, thus preventing any impairment of the surface quality.

[0048] Process variant B opens up the possibility of providing at least one ornament with a coating that contrasts with the surrounding lacquer layer, without unintentionally contaminating the uncut areas of the base body, since the carrier acts as a mask. For example, the walls and base of the ornament can be sprayed with a liquid lacquer or metallized, for example, with a metallic, reflective silver layer. The carrier can then be removed. This allows elegant color demarcations to be created.

[0049] In a further further embodiment, it can be provided that the lacquer layer surrounding the at least one ornament and / or the coating of the ornament is painted over.

[0050] Various effects can be achieved by painting over the lacquer layer and / or the coating of the ornament. On the one hand, it is possible to protect the lacquer layer and / or the coating by applying a harder layer, particularly a scratch-resistant layer. If a sensor is arranged in or on the ornament and / or in or on the base body, the scratch-resistant layer can be transparent to the sensor. Visually appealing effects can also be achieved, for example, by using metallic or reflective surfaces.

[0051] A first independent subject matter relates to a cover panel produced according to the method described above.

[0052] A further independent subject matter relates to a cover panel having a base body in which at least one ornament is incorporated on a first side, wherein the at least one ornament is formed as a recess opposite a surface of the first side, wherein the base body is coated with a lacquer layer, wherein the ornament is free of the lacquer layer.

[0053] In a first further embodiment, it can be provided that the ornament is formed into the base body by primary shaping, forming or machining processes.

[0054] The base body can in particular be injection-molded, wherein the at least one ornament is formed in the mold.

[0055] In a further embodiment, it can be provided that the paint layer contains soot as the only pigment.

[0056] In a further embodiment, the at least one ornament can be provided with the coating which contrasts in color with the lacquer layer.

[0057] In another further embodiment, it can be provided that the lacquer layer and / or the coating is painted over.

[0058] The overcoat can have optical effects and / or technical effects, for example a scratch-resistant coating or a reflective or metallic coating.

[0059] According to a further embodiment, it can be provided that the base body is coated on the side opposite the ornament.

[0060] In another further embodiment, it can be provided that a sensor is arranged in or on the ornament or in or on the base body.

[0061] A corresponding sensor can in particular be a radar sensor, lidar sensor or ultrasonic sensor.

[0062] Further advantages, features, and details will become apparent from the following description, which – where appropriate with reference to the drawings – describes at least one embodiment in detail. Identical, similar, and / or functionally equivalent parts are provided with the same reference numerals.

[0063] They show schematically: Fig. 1 a cover panel in an exploded view; Fig. 2 the cover panel Fig. 1 from an outside; Fig. 3 shows a section of a cover panel in a second embodiment; Fig. 4 shows a section of a cover panel in a second embodiment with a sensor; Fig. 5 a section of the cover panel Fig. 1 along the section line BB from Fig. 2; Fig. 6 a first process step for producing a cover panel according to Fig. 1; Fig. 7 a second process step for producing a cover panel according to Fig. 1; Fig. 8 an illustrative third process step for producing a cover panel according to Fig. 1; Fig. 9 a fourth process step for producing a cover panel according to Fig. 1, and Fig. 10 a fifth process step for producing a cover panel according to Fig. 1.

[0064] For better readability, identical or equivalent components are given the same reference numerals in the following embodiments.

[0065] The process step from Fig. 8 does not fall within the wording of the claims, but is considered to facilitate the understanding of the invention.

[0066] Fig. 1 shows a cover panel 2 in an exploded view.

[0067] The cover panel 2 has a base body 4 into which an ornament 6 is inserted. In the base body 4, further Fig. 1 invisible, smaller ornaments added.

[0068] The cover panel 2 has an outer side 8 and an inner side 10. As shown in the Fig. 3 to 10, the ornament is designed as a depression.

[0069] The cover panel 2 further comprises a panel 12 that covers an edge of the cover panel 2. Furthermore, an opaque lacquer layer 14 is provided that covers the base body 4. The lacquer layer 14 has several recesses 16 that are formed around the ornament 6 and the Fig. 1 invisible, smaller ornaments are formed around.

[0070] Behind the lacquer layer 14, a PVD layer 18 is provided, which in turn is covered by a protective layer 20. The PVD layer 18 and the protective layer 20 protect the base body from damage from the inner side 10. The PVD layer 18 and the protective layer 20 are transparent to rays at radar wavelengths.

[0071] Behind the protective layer 20, a radar sensor 22 is provided behind the ornament 6, which senses through the base body 4, i.e. sends and receives radar beams.

[0072] Radar sensor 22 and ornament 6 are arranged one behind the other for different reasons. Radar sensor 22 is technically optimally positioned in the center of the vehicle. For aesthetic reasons, this is also the best location for ornament 6.

[0073] An electric heater 24 is provided in the base body 4, viewed from the outer side 8, which is necessary to heat the outer side 8 so that it remains free of ice so that the radar sensor 22 functions properly even at low outside temperatures.

[0074] In the exploded view after Fig. 1 shows some layers, which may, however, be supplemented by further layers, for example primer layers and scratch-resistant protection layers.

[0075] Fig. 2 shows the cover panel 2 from Fig. 1 in a view from the outside 8.

[0076] In addition to the ornament 6, further ornaments 26 are incorporated into the base body 4, which primarily create optical effects, e.g., display a symbol. The cover panel 2 is arranged on the front of a schematically illustrated motor vehicle 28.

[0077] The Fig. 3-5 show sections through various cover panels 2, 2' generally along a section line corresponding to the section line BB of Fig. 2.

[0078] Fig. 3 shows a second embodiment of a cover panel 2'.

[0079] The outer side 8 is shown at the top, the inner side 10 at the bottom. Viewed from the outer side 8, the base body 4 is coated with a primer layer 30, which creates a smooth surface. The primer layer 30 is covered with a scratch-resistant protective layer 32. The scratch-resistant protective layer 32 is particularly hard and protects the cover panel 2 from damage, for example, from stone chips.

[0080] The lacquer layer 14 is coated with a primer layer 34, followed by a PVD layer 18. The PVD layer 18 is coated with a protective layer 20.

[0081] The ornament 6 is formed as a recess opposite a surface 36 of the base body 4. The lacquer layer 14 is cut out at an ornament edge 6.1 of the ornament 6. This ensures that the ornament side surfaces 6.2 and an ornament base 6.3 are free of the lacquer layer 14. Thus, negative influences on the function of a radar sensor due to reduced transparency for radar beams by the lacquer layer 14 can be prevented.

[0082] Fig. 4 shows the cover panel 2' from Fig. 3 with radar sensor 22 arranged behind it.

[0083] The ornament 6 is potted with a potting compound 37. This creates a composite plug 38 that fills the ornament 6. The composite plug 38 ensures a uniform material thickness and prevents interference caused by reflections and refractions of radar beams on the ornament. The radar sensor 22 is mounted behind the potting compound 37 on a vehicle body (not shown).

[0084] The composite plug 38 made of potting compound 37 creates a radar-transparent area 40 through which the radar sensor 22 can transmit and receive radar beams.

[0085] Fig. 5 shows the cover panel 2 from Fig. 1 along the section line BB from Fig. 2.

[0086] Regarding the basic structure, please refer to the description of the cover panel 2' from the Fig. 3 and Fig. 4.

[0087] In addition to the embodiment in Fig. 4 is the Fig. 1, the heater 24 is arranged in the base body 4 and coated with the primer layer 30 and the scratch-resistant protective layer 32.

[0088] The heater 24 is inserted into a corresponding mold and back-injected during injection molding of the base body 4.

[0089] The Fig. 6 to Fig. 10 show various process steps for producing the cover panel 2.

[0090] The base body 4 is to be coated from the inside 10 with a transfer varnish 44.

[0091] The transfer varnish film 44 consists of the opaque varnish layer 14, which is supported by a plastic film 46. The plastic film 46 is made of polypropylene with a thickness of approximately 120 µm. Polypropylene is non-polar and therefore well suited for transferring the opaque varnish layer. The opaque varnish layer 14 is manufactured as a plastic dispersion with carbon black particles incorporated into a polyurethane base.

[0092] The transfer varnish film 44 is placed on the base body 4.

[0093] In Fig. 7 shows that the transfer varnish film 44 is applied to the base body 4 using negative pressure.

[0094] The transfer lacquer film 44 spans the ornament 6, whereby a cavity 48 is created between the ornament edge 6.1, ornament sides 6.2 and ornament base 6.3 on the one hand and the transfer lacquer film 44 on the other hand.

[0095] The rigidity of the plastic film 46 is such that it does not penetrate into the ornament 6 and does not stick to the ornament base 6.3.

[0096] After applying the transfer varnish film 44, the plastic film 46 is removed. A continuous varnish layer 14 remains on the base body 4, covering the entire base body 4 including the ornament 6.

[0097] As in the illustrative example after Fig. 8, a part of the lacquer layer 14 spanning the ornament is cut off using a laser 50.

[0098] The laser 50 emits a laser beam 52, which is guided along the ornamental edge 6.1. Optical detection methods can be used to position and guide the laser 50 relative to the base body 4. The optical detection methods can, for example, detect edges of the base body 4.

[0099] The laser beam 52 is oriented essentially parallel to the surface normal n of the base body 4 in the area of the ornamental edge 6.1, creating a clean, locally vertical cutting edge.

[0100] Laser 50 and base body 4 are positioned relative to each other using a camera 53. A laser control system (not shown) uses image recognition methods to detect edges in and / or on the base body 4 and, from this, to determine the position and orientation of base body 4 and laser 50 relative to each other.

[0101] As in Fig. As shown in Figure 9, a layer residue 54 which remains in the ornamental base 6.3 after cutting by means of laser 50 is sucked off by means of a suction device 56.

[0102] What remains is, as in Fig. 10, a base body 4 with a lacquer layer 14, which forms a clean recess 16 around the ornament 6. List of reference symbols 2, 2' cover panel 4 basic bodies 6 Ornament 6.1 Ornamental border 6.2 Ornament side 6.3 Ornamental background 8 Outside 10 Inside 12 aperture 14 coats of paint 16 recess 18 PVD layer 20 protective layer 22 radar sensor 24 heating 26 Ornament 28 Motor vehicle 30 primer layers 32 Kraftfest protective layer 34 Primer layer 36 Surface 37 Potting compound 38 potting plugs 40 radar-transparent area 44 transfer varnish foil 46 plastic film 48 cavity 50 lasers 52 laser beam 53 Camera 54 shift residue 56 Extraction device n surface normal

Claims

[1] Method for producing a cover panel (2; 2'), wherein the cover panel (2; 2') has a base body (4) in which at least one ornament (6, 26) is introduced on a first side (10), wherein the at least one ornament (6, 26) is formed as a depression opposite a surface (36) of the first side (10), wherein the base body (4) is coated with a lacquer layer (14), wherein for applying the lacquer layer (14) a transfer lacquer film (44) is applied to the base body (4) so that the transfer lacquer film (44) spans the at least one ornament (6, 26), wherein the at least one ornament (6, 26) is cut free after the application of the transfer lacquer film (44), wherein the transfer lacquer film (44) comprises the lacquer layer (14) and a plastic film as a carrier (46), and the carrier (46) after the application of the transfer lacquer film (44) to the base body (4) is peeled off to expose the lacquer layer (14), whereby the cutting is carried out,before the carrier (46) of the transfer varnish film (44) is removed to expose the varnish layer (14). [2] Method according to claim 1, characterized by that the transfer lacquer film (44) is pressed onto the base body (4) when it is applied thereto, the plastic film (46) remaining so dimensionally stable when pressed on that it does not extend to a base (6.3) of the at least one ornament (6, 26). [3] Method according to claim 1 or 2, characterized by that the pressing of the transfer lacquer film (44) onto the base body (4) is carried out in a negative pressure atmosphere. [4] Method according to one of the preceding claims, characterized by that the free cutting is carried out by means of a laser (50) which scans an ornamental edge (6.1) of the ornament (6, 26). [5] Method according to claim 4, characterized by that the laser (50) is guided parallel to a surface normal (n) of the base body (4). [6] Method according to claim 4 or 5, characterized by that a position of the at least one ornament (6, 26) is detected by means of an optical detection device (53) and the laser (50) and cover panel (2; 2') are positioned and moved relative to one another on the basis of the position determined by means of the optical detection device (53). [7] Method according to one of the preceding claims, characterized by that the introduction of the ornament (6, 26) into the base body (4) is carried out by primary shaping or forming or machining processes. [8] Method according to one of the preceding claims, characterized by that the lacquer layer (14) uses soot as the only pigment. [9] Method according to one of claims 1 to 8, characterized by that the at least one ornament (6, 26) is provided with a coating after cutting free and before removing the carrier (44). [10] Method according to one of claims 1-9, characterized bythat the paint layer (14) is painted over.

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