Cover element and method for manufacturing a cover element

Abstract

Cover element, in particular for the external cladding of a motor vehicle, comprising: - an injection-molded main body (1) made of a transparent or translucent polymer material (2) and, - a planar supporting structure (3) with at least one heating conductor (4) applied to the supporting structure (3), which can be heated by an electric current or by radiation, wherein the heating conductor (4) is arranged on the supporting structure (3) in a predefined laying geometry, wherein the supporting structure (3) is connected to the main body (1) via an overmolding of the supporting structure (3) or via an overmolding of the supporting structure (3) with the polymer material (2) of the main body (1), characterized by the fact that the supporting structure (3) is a net-shaped surface structure (3) and the heating conductor (4) is connected to the net-shaped surface structure (3) in a materially bonded and / or form-fitting manner, thereby fixing the laying geometry of the heating conductor (4) in position, wherein the polymer material (2) of the main body (1) penetrates the net-shaped surface structure (2).

Description

[0001] The present invention relates to a cover element, in particular for the outer cladding of a motor vehicle, comprising an injection-molded main body 1 made of a transparent or translucent polymer material 2 and a flat support structure 3 with at least one heating conductor 4 applied to the support structure 3, which heating conductor can be heated by current supply or by radiation, wherein the heating conductor 4 is arranged in a predefined laying geometry on the support structure 3, wherein the support structure 3 is connected to the main body 1 via a back-injection of the support structure 3 or via an over-injection of the support structure 3 with the polymer material 2 of the main body 1.

[0002] Examples of generic cover elements can be found in the documents DE 197 24 320 A1, DE 198 29 554 A1, DE 10 2011 107 216 A1, EP 3 565 058 A1, EP 3 252 494 A1, DE 10 2014 214 329 A1, DE 10 2014 002 438 A1 and DE 10 2011 122 345 A1.

[0003] With all of these cover elements known from the prior art, there is a risk that the support structure in the main body remains clearly visible due to the transparent or translucent polymer material of the injection-molded main body, thereby impairing the overall aesthetic impression of the cover element. Since such cover elements are generally used in the visible area, particularly in motor vehicles, this is often unacceptable. In addition, the prior art uses carrier films as the support structure for the heating conductor, whereby visible gas inclusions or phase boundaries arise due to a lack of bond between the polymer material and the carrier film. In addition, the adhesion between the carrier film and the polymer material is then insufficient, and there is a risk of damage, for example from water ingress.

[0004] The object of the present invention is therefore to provide a cover element in which the support structure is almost or not at all visible in the polymer material of the main body and the adhesion of the polymer material and the planar support structure is improved.

[0005] This object is achieved according to the invention by a covering element, in particular for the external cladding of a motor vehicle, comprising: - an injection-molded main body made of a transparent or translucent polymer material and, - a flat support structure with at least one heating conductor applied to the support structure, which can be heated by current supply or by irradiation, wherein the heating conductor is arranged in a predefined laying geometry on the support structure, wherein the support structure is connected to the main body via a back-injection of the support structure or via an over-injection of the support structure with the polymer material of the main body, wherein the support structure is a net-shaped flat structure and the heating conductor is connected to the net-shaped flat structure in a material-locking and / or form-locking manner and as a result the laying geometry of the heating conductor is fixed in position, wherein the polymer material of the main body penetrates the net-shaped flat structure.By designing the support structure as a mesh-like sheet material with a multitude of periodically or aperiodically arranged openings, the polymer material of the main body penetrates the mesh-like sheet material during its manufacture, significantly reducing the visual recognizability of the support structure. At the same time, due to this penetration and the associated partial or complete enclosing of the mesh-like sheet material, a reliable bond is created between the mesh-like sheet material and the polymer material of the main body.

[0006] The heating conductor can comprise a heating wire or be formed by a heating wire. The electrically conductive wire used as the heating wire can preferably be made of copper or a copper alloy, or nickel or a nickel alloy, or iron or an iron alloy, or silver or a silver alloy, or gold or a gold alloy. The wire used as the heating wire preferably has a diameter in the range of 40 µm to 450 µm.

[0007] The net-like sheet structure can preferably be a perforated film or a mesh net. For a mesh net, threads are preferably used, in particular threads made of a thermoplastic material, particularly preferably a translucent or transparent thermoplastic material.

[0008] Typical values ​​for the thickness of the reticulated sheet are in the range of 150 µm to 800 µm, preferably in the range of 200 µm to 500 µm, particularly preferably in the range of 250 µm to 400 µm. The typical wall thickness of the injection-molded main body is in the range of 1.5 mm to 3.5 mm, preferably in the range of 1.8 mm to 2.7 mm.

[0009] The transparent polymer material may comprise or consist of a polycarbonate, polymethyl methacrylate, polyamide, polyolefin, polypropylene, polyethylene or acrylonitrile-butadiene-styrene copolymer.

[0010] Preferably, the cover element forms or is used for a cover for a sensor or a cover for a radar unit (radome) or a cover for a camera or a cover for a lidar unit or a cover for a lighting unit.

[0011] The heating conductor is preferably welded, soldered, or glued to the fabric. Alternatively, or in combination, the heating conductor can be joined to the fabric using a textile method. In particular, the heating conductor can be sewn, woven, knotted, knitted, braided, bobbin-laced, spun, or twisted to the fabric. A corresponding fabric can be easily prefabricated.

[0012] The net-like sheet-like structure preferably also consists of a polymer material, in particular a thermoplastic polymer material. Particularly preferably, the material of the net-like sheet-like structure is compatible, of the same type, or identical to the polymer material of the main body.

[0013] The invention further comprises a method for producing a cover element, in particular for the outer cladding of a motor vehicle, wherein the cover element has an injection-molded main body made of a transparent polymer material and a support structure with at least one heating conductor applied to the support structure.

[0014] The procedure includes the following steps: - Providing a flat support structure with a heating conductor applied to the support structure, which can be heated by current or by irradiation, wherein the heating conductor is arranged on the support structure in a predefined laying geometry, - arranging the support structure in a cavity of an injection moulding tool formed between at least two mould halves and defining a main body, - Injecting a plasticized polymer material into the cavity of the injection mold to form the main body, - Connecting the supporting structure to the main body by back-injecting the supporting structure or by over-injecting the supporting structure with the polymer material of the main body, - cooling and demoulding the cover element thus formed, wherein the supporting structure is a net-shaped sheet-like structure and the heating conductor is materially and / or positively connected to the net-shaped sheet-like structure when arranged in the cavity and the laying geometry is thereby fixed in position, wherein the net-shaped sheet-like structure is penetrated by the polymer material during the injection of the plasticised polymer material.

[0015] The material and mass of the net-shaped sheet can be selected such that the thermal energy of the plasticized polymer material is sufficient to melt or partially melt the sheet. With regard to the material, attention must be paid to the compatibility of the material of the net-shaped sheet with the polymer material of the main body. Furthermore, with regard to the material, the softening temperature or melting range or melting point of the material of the net-shaped sheet must be taken into account. The mass of the net-shaped sheet can be influenced in particular by the thickness of the net-shaped sheet. If threads are used to produce the net-shaped sheet, the mass of the net-shaped sheet can also be influenced accordingly via the thread thickness and / or a mesh size.

[0016] Melting or melting the reticulated sheet material further reduces its visual visibility or makes it largely invisible due to its dissolution into the plasticized polymer material of the base body. If the reticulated sheet material completely dissolves due to the thermal energy of the plasticized polymer material of the base body, the process must be controlled so that the solidification of the plasticized polymer material of the base body occurs immediately after the dissolution of the reticulated sheet material, in order to prevent the laying geometry of the heating conductor from being shifted or destroyed.

[0017] Preferably, at least one of the tool halves of the injection molding tool has additional heating in the region of the net-shaped sheet-like structure, which heating enables a locally elevated temperature of at least one tool half in the region of the sheet-like structure compared to the remaining at least one tool half. Due to the locally elevated temperature of at least one tool half in the region of the sheet-like structure, the viscosity of the plasticized polymer material (i.e. the polymer melt) of the main body in the region of the sheet-like structure is reduced and / or the plasticized polymer material in the region of the sheet-like structure is kept in the plasticized state for longer. This facilitates the penetration of the net-shaped sheet-like structure with the plasticized polymer material. The heating is preferably operated variothermally.

[0018] The at least two mold halves may not be completely closed during the injection of the plasticized polymer material, and the mold halves can only be closed during the solidification process of the polymer material. Alternatively, or in combination, the mold halves can be opened due to the internal pressure that increases during the injection of the polymer material, and the mold halves can only be closed again during the solidification process of the polymer material. Through these process steps, known as injection-compression molding, the visual recognizability of the net-like surface structure within the polymer material of the main body can be further minimized. In particular, if the net-like surface structure dissolves due to the thermal energy of the plasticized polymer material, the risk of shifting the laying geometry of the heating conductor can be minimized by an injection-compression molding process step.

[0019] The invention is explained in more detail using figures which merely represent exemplary embodiments.

[0020] They show: Fig. 1 and Fig. 2: Examples of a cover element with different geometries of the net-like surface structure; Fig. 3 and Fig. 4: Partial cross-sectional views of examples of a cover element; Fig. 5 to 8: Sequences of individual sub-steps of the method according to the invention; Fig. 9 to 10: further examples of a cover element in the form of a brand emblem, each with different geometries of the surface structure.

[0021] Identical or functionally equivalent elements are provided with the same reference symbols.

[0022] The Fig. 1 and the Fig. 2 each show a cover element, in particular for the outer cladding of a motor vehicle, comprising an injection-molded main body 1 made of a transparent or translucent polymer material 2 and a flat support structure 3 with at least one heating conductor 4 applied to the support structure 3, which can be heated by current or by radiation, wherein the heating conductor 4 is arranged in a predefined installation geometry on the support structure 3. The support structure 3 is connected to the main body 1 via a back-injection of the support structure 3 or via an over-injection of the support structure 3 with the polymer material 2 of the main body 1.

[0023] The supporting structure 3 is a net-shaped sheet 3, and the heating conductor 4 is connected to the net-shaped sheet 3 by a material fit and / or form fit. This fixes the laying geometry of the heating conductor 4 in position, with the polymer material 2 of the main body 1 penetrating the net-shaped sheet 3. The heating conductor 4 comprises a heating wire. The net-shaped sheet 3 is in Fig. 1 and Fig. 2 is shown visibly for clarity, although the surface structure is no longer visible in reality.

[0024] The Fig. 1 and Fig. 3 The surface structure 3 shown schematically in cross-section is designed as a mesh network. Fig. 2 and Fig. 4 schematically illustrated planar structure 3 is designed as a perforated foil.

[0025] For all cover elements described above, the transparent polymer material 2 may comprise a polycarbonate, polymethyl methacrylate, polyamide, polyolefin, polypropylene, polyethylene or acrylonitrile-butadiene-styrene copolymer or consist of one of these materials.

[0026] For the cover elements described above, it may also apply that the cover element forms or is used as a cover for a sensor or a cover for a radar unit (radome) or a cover for a camera or a cover for a lidar unit or a cover for a lighting unit.

[0027] In addition, for all the cover elements described above, the net-shaped surface structure 3 may be made of a material that is compatible, of the same type or identical to the polymer material 2 of the main body 1.

[0028] Furthermore, for all the cover elements described above, the heating conductor 4 can be welded, soldered, or glued to the fabric 3. Alternatively or additionally, the heating conductor 4 can be textile-jointed to the fabric 3, in particular sewn, woven, knotted, knitted, braided, bobbin-laced, spun, or twisted.

[0029] Based on the Fig. 5 to Fig. 8, the method for producing a covering element, in particular for the outer cladding of a motor vehicle, is described below.

[0030] The cover element has an injection-molded main body 1 made of a transparent polymer material 2 and a flat support structure 3 with at least one heating conductor 4 applied to the support structure 3.

[0031] The procedure includes the following steps: In the Fig. 5 shows the provision of a flat support structure 3 with a heating conductor 4 applied to the support structure 3, which can be heated by current supply or by irradiation, wherein the heating conductor 4 is arranged in a predefined laying geometry on the support structure 3.

[0032] In Fig. 6 shows the step of arranging the support structure 3 in a cavity 12 of an injection molding tool 13 formed between at least two tool halves 10, 11 and defining a main body 1.

[0033] In Fig. 7, the injection of a plasticized polymer material 2 into the cavity 12 of the injection molding tool 13 takes place in order to form the main body 1, as well as the step of connecting the support structure 3 to the main body 1 by back-injection of the support structure 3 or by over-injection of the support structure 3 with the polymer material 2 of the main body 1.

[0034] Finally, in Fig. 8 shows the cooling and demoulding of the cover element thus formed.

[0035] Especially in Fig. 3 to Fig. 7 it can be seen that the support structure 3 is a net-shaped sheet 3 and the heating conductor 4 is materially and / or positively connected to the net-shaped sheet 3 when arranged in the cavity 12 and thereby the laying geometry is fixed in position, wherein the net-shaped sheet 3 is penetrated by the polymer material 2 during the injection of the plasticized polymer material 2.

[0036] The material and the mass of the net-shaped sheet 3 can be selected such that the thermal energy of the plasticized polymer material 2 is sufficient to melt or melt the sheet 3.

[0037] In variations of the illustrated method steps not shown in detail, the at least two mold halves 10, 11 may not be completely closed during the injection of the plasticized polymer material 2, and the mold halves 10, 11 may only be closed during the solidification process of the polymer material 2. Alternatively, or in combination, the mold halves 10, 11 may be opened due to the internal pressure increasing during the injection of the polymer material 2, and the mold halves 10, 11 may only be closed again during the solidification process of the polymer material 2.

[0038] In the Fig. 9 and Fig. 10 are analogous to those in Fig. 1 and Fig.2, wherein these cover elements are designed as brand emblems. For this purpose, the cover elements additionally have a brand logo applied to the main body 1 or injected into the main body 1. The net-like surface structures 3 are only indicated in outline, as they are no longer recognizable in reality.

Claims

[1] Cover element, in particular for the external cladding of a motor vehicle, comprising: - an injection-molded main body (1) made of a transparent or translucent polymer material (2) and, - a flat support structure (3) with at least one heating conductor (4) applied to the support structure (3), which can be heated by current or by radiation, wherein the heating conductor (4) is arranged in a predefined laying geometry on the support structure (3), wherein the support structure (3) is connected to the main body (1) via a back-injection of the support structure (3) or via an over-injection of the support structure (3) with the polymer material (2) of the main body (1), characterized by , that the supporting structure (3) is a net-shaped surface structure (3) and the heating conductor (4) is connected to the net-shaped surface structure (3) in a material-locking and / or form-locking manner and as a result the laying geometry of the heating conductor (4) is fixed in position, wherein the polymer material (2) of the main body (1) penetrates the net-shaped surface structure (2). [2] Cover element according to claim 1, characterized by that the heating conductor (4) comprises a heating wire. [3] Cover element according to claim 1 or 2, characterized by that the net-like surface structure (3) is a perforated foil or a mesh net. [4] Cover element according to one of the preceding claims, characterized by that the transparent polymer material (2) comprises a polycarbonate, polymethyl methacrylate, polyamide, polyolefin, polypropylene, polyethylene or acrylonitrile-butadiene-styrene copolymer or consists of one of these materials. [5] Cover element according to one of the preceding claims, characterized bythat the cover element forms or is used for a cover for a sensor or a cover for a radar unit or a cover for a camera or a cover for a lidar unit or a cover for a lighting unit. [6] Cover element according to one of the preceding claims, characterized by that the heating conductor (4) is welded, soldered or glued to the surface structure (3). [7] Cover element according to one of the preceding claims, characterized by that the heating conductor (4) is textile-joined to the fabric (3), in particular sewn, woven, knotted, knitted, braided, bobbin-lacquered, spun or twisted. [8] Cover element according to one of the preceding claims, characterized by that the net-shaped surface structure (3) consists of a material which is compatible, of the same type or identical to the polymer material (2) of the main body (1). [9] Method for producing a covering element, in particular for the outer lining of a motor vehicle, wherein the covering element has an injection-molded main body (1) made of a transparent polymer material (2) and a flat support structure (3) with at least one heating conductor (4) applied to the support structure (3), comprising the following steps: - Providing a flat support structure (3) with a heating conductor (4) applied to the support structure (3), which heating conductor can be heated by current supply or by irradiation, wherein the heating conductor (4) is arranged in a predefined laying geometry on the support structure (3), - arranging the support structure (3) in a cavity (12) of an injection moulding tool (13) formed between at least two tool halves (10, 11) and defining a main body (1), - injecting a plasticized polymer material (2) into the cavity (12) of the injection mold (13) to form the main body (1), - connecting the support structure (3) to the main body (1) by back-injecting the support structure (3) or by over-injecting the support structure (3) with the polymer material (2) of the main body (1), - Cooling and demoulding the cover element thus formed, characterized by that the support structure (3) is a net-shaped surface structure (3) and the heating conductor (4) is materially and / or positively connected to the net-shaped surface structure (3) when arranged in the cavity (12) and the laying geometry is thereby fixed in position, wherein the net-shaped surface structure (3) is penetrated by the polymer material (2) during the injection of the plasticized polymer material (2). [10] Method according to claim 9, characterized bythat the material and the mass of the net-shaped sheet structure (3) are selected such that the thermal energy of the plasticized polymer material (2) is sufficient to melt or melt the sheet structure (3). [11] Method according to claim 9 or 10 characterized by that the at least two tool halves (10, 11) are not completely closed during the injection of the plasticized polymer material (2) and the tool halves (10, 11) are only closed during the solidification process of the polymer material (2) or due to the internal pressure increasing during the injection of the polymer material (2), the tool halves (10, 11) are opened and the tool halves (10, 11) are only closed again during the solidification process of the polymer material (2).

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