METHOD FOR MANUFACTURING A MOTOR VEHICLE COMPONENT AND MOTOR VEHICLE COMPONENT

Abstract

The invention relates to a method for manufacturing a motor vehicle component (1) in which a multi-layered film composite (2) is back-injected with a plastic on its back side (9), wherein the film composite (2) comprises a cover layer (4) which provides a visible side (8) of the motor vehicle component (1) opposite the back side (9), an elastic foam layer (5) and a protective layer (6) which covers the foam layer (5) towards the back side (9) and provides the back side (9).

Description

Technical area

[0001] The invention relates to a method for manufacturing a motor vehicle component and to a motor vehicle component. State of the art

[0002] When back-injecting foam films, i.e., films with a foam backing, direct injection molding onto the foam can lead to sink marks or imprints due to foam washout and / or foam compaction. Furthermore, in this case, using holding pressure during injection molding to compensate for shrinkage is not possible due to the resulting pronounced imprints at the injection point. This can result in significant component warpage and sink marks on components produced by back-injecting the foam film. Description of the invention

[0003] The object of the present invention is to provide a solution which enables the particularly simple production of a motor vehicle component with a foam layer, the decoration of which is back-injected with a carrier component, wherein the motor vehicle component is produced with particularly few sink marks and imprints on its visible side.

[0004] This object is achieved by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description, and the figures. Features, advantages, and possible embodiments presented in the description for one of the subject matter of the independent claims are to be regarded at least analogously as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0005] The invention relates to a method for manufacturing a motor vehicle component, in particular an interior component, for the interior of a motor vehicle, especially a passenger car. In the method, a multilayer film composite is back-injected with a plastic. The film composite comprises a top layer, an elastic foam layer, and a protective layer. The foam layer is arranged between the top layer and the protective layer. Thus, the film composite has a sandwich structure consisting of the layers stacked one on top of the other in a stacking direction. The top layer provides a visible side of the motor vehicle component opposite the back side. This means that, under intended use, the top layer provides an outer surface of the motor vehicle component.If the automotive component is an interior part, then vehicle occupants can see the outer layer from inside the vehicle. This protective layer covers the foam layer on the reverse side and provides the backing. This means that during injection molding, the plastic is injected onto the protective layer. The protective layer prevents the foam layer from being displaced by the injection-molded plastic, thus avoiding unwanted marks. The protective layer therefore ensures that the foam layer remains in its designated position during back injection molding. Specifically, both the outer layer and the protective layer are provided by films. A film is a homogeneous sheet made of very thin plastic. In particular, the respective film is produced from plastic in sheets and is many times thinner than it is wide or long.

[0006] The elastic foam layer allows the automotive component, which comprises the film composite, to have a soft-touch surface. This elastic foam layer gives the component a supple feel, enabling it to visually and haptically imitate high-quality leather, for example. The process allows the automotive component to be supplied with a soft-touch surface while reducing the risk of foam damage, washout, compaction, and thus sink marks during injection molding, thanks to the protective layer.

[0007] In a possible further development of the invention, it is provided that the film composite is back-injected using a foam injection molding process. Injection molding is a primary forming process mainly used in plastics processing. In this process, the respective material, in this case the plastic, is liquefied and thus plasticized using an injection molding machine and injected under pressure into a mold, the injection mold. In the injection mold, the material transitions into a solid state through cooling or a cross-linking reaction and can be removed as a finished part after the mold is opened. The cavity of the mold determines the shape and surface structure of the finished component. This process allows for the cost-effective production of directly usable molded parts in large quantities. Foam injection molding, in particular thermoplastic foam injection molding, is a collective process within the field of injection molding.In this process, the plastic foams up in the cavity, for example, due to a blowing agent that can be added to the molten material in the injection molding machine. The cavity is initially partially filled to give the plastic the necessary space for its expansion during foaming. In injection molding, blowing agents are used to prevent sink marks, produce thick-walled molds, and / or save weight. The foam injection molding process allows the film composite to be back-injected with low or no pressure, effectively preventing sink marks. In the foam injection molding process, the plastic can be foamed physically or chemically. In physical foaming, a fluid, especially nitrogen or carbon dioxide, is introduced into the molten material. This occurs during melt plasticization.This means that the gas is introduced either directly into a plasticizing cylinder or into a nozzle of the plasticizing cylinder. The gas dissolves in the melt under appropriate pressure and expands as soon as the melt is injected into the mold. Alternatively, plastic granules can be pressurized with gas, causing the gas to diffuse into the individual granules. Once the melt obtained from the plastic granules has been injected into the mold, the gas expands. In volumetric filling, the gas expansion acts as the holding pressure, resulting in a component without sink marks and with minimal warpage. In chemical foaming, a blowing agent in powder or granule form is added to the plastic. This chemical additive decomposes, releasing a gas, usually carbon dioxide, during the plasticizing process as the temperature increases.Here too, the gas dissolves in the melt while maintaining a minimum pressure. The subsequent process sequence is the same as that of physical foaming.

[0008] In a further possible embodiment of the invention, the film composite is back-injected using a hot runner system with controllable needle opening speed. In the processing of plastics, particularly in the machine injection molding of thermoplastics, a hot runner system refers to a special type of gating system that is thermally insulated from the rest of the injection mold and heated to a higher temperature. In a hot runner system, the gating system is thermally separated from the rest of the mold and heated separately, ensuring that the molten plastic remains permanently fluid within the gating system. This prevents solidification of the plastic within the gating system, leaving no sprue on the component. Furthermore, the hot runner system allows for longer flow paths because the pressure drop at the gating system is not increased by cooling of the melt and the associated increase in viscosity.Especially in cascade injection molding, electrically driven needle valve nozzles allow for the individual, sequentially coordinated, and precise opening and closing of the valve needle at selectable speeds. This enables precise control of the melt flow in the individual hot runner nozzles and the overall volume flow in the cavity. The smooth opening and closing of the needles avoids the pressure drop and the associated pressure drop marking on the molded part, which are common problems in conventional cascade injection molding with its abrupt, sequential activation of the hot runner nozzles. Cascade injection molding is a form of sequential injection molding. It utilizes multiple needle valve nozzles, which make it possible to fill the plastic molded part via several gates. The hot runner system is used to ensure that the thermoplastic molding compound remains liquid.Cascade injection molding makes it possible to produce components with long flow paths and no weld lines, which is particularly important for high-quality components. Due to the low pressure, resulting from the fact that it is a low-pressure injection molding process, the clamping force of the injection molding machine can also be reduced. This allows the automotive component to be manufactured with very few sink marks or defects.

[0009] In another possible embodiment of the invention, a film composite is back-injected, the top layer of which comprises a film made of a thermoplastic polyolefin. Thermoplastic polyolefins are polymer or filler mixtures that typically consist of a proportion of a thermoplastic, an elastomer or rubber, and a filler. The surface of leather, for example, can be particularly well imitated using the thermoplastic polyolefin (TPO) film. Furthermore, TPO is a thermoformable material. This makes it possible to thermoform at least the surface layer in certain areas during the manufacturing of the automotive component.

[0010] In another possible embodiment of the invention, the film composite can be thermoformed into a mold and subsequently back-injected. Thermoforming is the tensile-compressive forming of a hollow body open on one side. Thermoforming the film composite is understood to be a process in which the film composite is formed using heat and compressed air or a vacuum. Due to the surface similarity of thermoforming to deep drawing of metal sheets, thermoforming is also referred to as vacuum deep drawing or deep drawing. Thermoforming allows for the realization of complex geometries of the automotive component. In particular, thermoforming and injection molding can be performed in the same mold.In this process, the film composite can be formed onto one half of the injection mold, for example using a vacuum, and then the plastic is injected onto the back of the film composite. This allows the automotive component to be manufactured particularly easily and quickly.

[0011] In this context, it may be particularly useful to apply a grain pattern to the top layer during thermoforming by placing the top layer against the mold, whose surface contour contains the grain pattern to be applied in negative, and drawing it against the mold using a vacuum. In other words, the automotive component can be manufactured using the so-called in-mould graining process. In-mould graining is a lamination process in which an unembossed thermoplastic polyolefin (TPO) foam film is laminated onto a substrate and receives its grain pattern in the same step. This process allows for greater design freedom than a method using pre-grained films, which could distort their grain during lamination. Since the grain is created during the thermoforming process in in-mould graining, the pattern remains precise even on sharp edges and radii.In in-mold graining (IMG), the grain of the film composite, or the TPO film providing the top layer, is created during the thermoforming process. The grain structure of an IMG shell is transferred to the originally ungrained film, in this case the top layer film, during the laminating / deep-drawing process. The upper mold with the shaping grain can be designed to be porous and thus air-permeable for thermoforming. The skin produced from the film composite by thermoforming can be further processed by back-foaming or back-injection molding. Grain embossing and laminating onto a substrate are thus performed in a single step.

[0012] The invention further relates to a motor vehicle component comprising a film composite consisting of a top layer, an elastic foam layer, and a protective layer. The top layer forms one visible side of the motor vehicle component. The protective layer covers the foam layer on the reverse side opposite the visible side. Furthermore, the protective layer forms the reverse side of the motor vehicle component. A carrier component is injection-molded onto the film composite on the reverse side of the motor vehicle component opposite the visible side. The motor vehicle component is manufactured, in particular, using a method already described in connection with the inventive method for manufacturing a motor vehicle component. The protective layer effectively prevents foam damage, erosion, compaction, and thus sink marks in the foam layer during injection molding.This makes it particularly easy to avoid visible marks caused by shifting foam layers on the visible side.

[0013] In another possible embodiment of the invention, the support component is a foam component. This means that the film composite has been back-injected using a foam injection molding process. The plastic, which is thus injected onto the film composite, is therefore foamed. This allows the required holding pressure when filling the injection mold with the plastic to be kept particularly low, since the foaming process ensures that the plastic completely fills the mold. This significantly reduces the risk of foam damage, washout, compaction, and consequently, sink marks in the foam layer during injection molding, due to the low pressure of the plastic injected on the back side.

[0014] In a further possible embodiment of the invention, the film composite comprises a top layer made of a thermoplastic polyolefin film, providing the visible side, and / or an elastic foam layer made of polypropylene or polyethylene, and / or a protective layer made of a thermoplastic polyolefin film, providing the reverse side. The film composite thus has a sandwich structure consisting of the top layer, the protective layer, and the foam layer arranged between the top layer and the protective layer, wherein the top layer and / or the protective layer are made of the thermoplastic polyolefin film. This ensures that the film composite can be thermoformed particularly well. By providing the foam layer as a polypropylene or polyethylene, the elasticity of the foam layer can be particularly well guaranteed.

[0015] In another possible embodiment of the invention, the automotive component is designed as an interior component. Due to the component's construction with the film composite laminated onto the carrier component, it can be provided with a soft-touch surface, which is particularly well-suited for use in the interior of a motor vehicle, especially to imitate a leather surface. This allows for a high-quality leather look in the interior using non-animal materials. In particular, the automotive component has a reproducible appearance, thus ensuring consistent quality of the interior component for series production vehicles.

[0016] Further advantages, features, and details of the invention may become apparent from the following description of possible embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as those shown below in the figure description and / or in the figures themselves, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention. Brief character description

[0017] The drawing shows in: Fig. 1. A process diagram for a process for manufacturing a motor vehicle component; and Fig. 2 a partial sectional view of the motor vehicle component.

[0018] In Fig. Figure 1 shows a process diagram for a method for manufacturing a motor vehicle component 1. The motor vehicle component 1 could, for example, be a glove box component. This motor vehicle component 1, manufactured within the framework of the method, is in Fig. Figure 2 shows a sectioned view. The motor vehicle component 1 is specifically designed for use as an interior component in the interior of a motor vehicle, particularly a passenger car. The motor vehicle component 1 comprises a film composite 2 and a carrier component 3, which is laminated by the film composite 2. In this case, the carrier component 3 is a foam component manufactured using an injection molding process.

[0019] The film composite 2 comprises a top layer 4, a foam layer 5, and a protective layer 6. The layers of the film composite 2 are stacked on top of each other in a stacking direction 7, giving the film composite 2 a sandwich structure. In the automotive component 1, the top layer 4 provides a visible side 8 of the automotive component 1. The visible side 8 is a visible side of the automotive component 1 when used as intended in the vehicle. The protective layer 6 is located on a side of the foam layer 5 opposite the top layer 4 and provides a back side 9 of the film composite 2 opposite the visible side 8. The foam layer 5 is thus located between the top layer 4 and the protective layer 6. At this back side 9 of the film composite 2, the film composite 2 is in contact with the carrier component 3. This means that the carrier component 3 rests against the back side 9 of the film composite 2.Rib packages can be injection-molded onto the rear side 9 as a support component 3. The protective layer 6 is designed to protect the foam layer 5 from damage. In this case, the cover layer 4 and the protective layer 6 are each provided by a thermoplastic polyolefin film. The foam layer 5 consists of polypropylene or polyethylene. The support component 3 consists of a foamed plastic.

[0020] The motor vehicle component 1 is part of the in Fig.The film composite 2 is produced according to the method shown in Figure 1. In a first process step V1, a robotic device picks up a stacked blank of the film composite 2 and moves the film composite 2 to a heating device. For picking up and moving the film composite 2, the robotic device can have a robot arm with a gripper at its end. The gripper can pick up the film composite 2 and hold it during transport. This robotic device is, in particular, an industrial robot. An industrial robot is a universal, programmable machine for handling, assembling, or processing workpieces. The industrial robot generally consists of the manipulator, which can also be called the robot arm, the controller, and an effector, which is a tool, gripper, or similar device.

[0021] In the second process step V2, the film composite 2 is heated by means of the heating device. For this purpose, the heating device can include an infrared radiator array, allowing the film composite 2 to be heated via infrared radiation. In a third process step V3, the heated film composite 2 is transferred to an injection mold. This means that the film composite 2 is placed into the injection mold. In a subsequent fourth process step V4, the film composite 2 is thermoformed by drawing it onto the injection mold, for example, by applying a vacuum, to create a textured embossing. The area of ​​the injection mold where the film composite 2 is drawn onto the visible side 8 of the film composite 2 forms a negative impression of the structure to be introduced into the film composite 2, in this case, a textured surface.The film composite 2 is thus thermoformed in the mold of the injection mold. During thermoforming, the top layer 4 is provided with the textured surface by applying the top layer 4 to the mold, whose surface contour has the textured surface in negative, and drawing it against this mold using a vacuum.

[0022] In a fifth process step V5 of the process, the injection mold is closed and the film composite 2 is back-injected on its rear side 9. This means that the plastic is injected onto the rear side 9 of the film composite 2 during the injection molding process. In this case, the film composite 2 is back-injected using a foam injection molding process. To enable the plastic to be injection molded with particularly low post-injection pressure, the film composite 2 is back-injected during injection molding using a hot runner system with controllable needle opening speed of the respective needles of a needle valve system within the hot runner system. The plastic foams up in the injection mold, creating the support component 3 from the foamed plastic.

[0023] In a sixth process step V6, the manufactured automotive component 1 cools in the injection mold. Subsequently, at least one edge area of ​​the film composite 2 can be folded over by means of a slide. Alternatively or additionally, a die-cut trimming of the automotive component 1 can be performed, in which at least one edge of the film composite 2 is cut off. This die-cut trimming is carried out in particular after forming the film composite 2 including the fold-over formation, whereby a slide is retracted, the mold is closed, the slide is advanced, and the trimming occurs against a mold core. Following this, the automotive component 1 is released by opening the injection mold. In a seventh process step V7 of the process, the automotive component 1 is removed from the injection mold.

[0024] Alternatively, the film composite 2 can be fed to the heating unit as a roll and heated section by section. Subsequently, the film composite 2 can be back-injected section by section in the injection mold, whereby the finished automotive component is separated from the remaining roll material during the die-cutting process.

[0025] This involves a combination of a three-layer foam film, in this case the film composite 2, with a deformable or deep-strength film made of a thermoplastic polyolefin, approximately 0.1 to 0.4 millimeters thick, which provides the protective layer 6. This film protects the foam layer 5 from sink marks. The foam injection molding process uses chemical or physical foaming, allowing for particularly low pressure and minimal warpage. This design is especially advantageous when the carrier component 3 is directly injection molded onto the protective layer 6. The foam layer 5 can have a thickness of one to three millimeters in the stacking direction 7. The top layer 4 can have a thickness of 0.5 to 0.7 millimeters in the stacking direction 7. The thickness of the protective layer 6 in the stacking direction 7 can be 0.1 to 0.4 millimeters.In particular, the support component 3 can have a wall thickness of two to three millimeters in the stacking direction 7.

[0026] To prevent shear wrinkles during cascade filling in injection molding, a hot runner system with controllable needle opening speed is used. This ensures a uniform pressure and shrinkage distribution, thereby reducing component warpage and preventing sink marks. To avoid pronounced marks at the injection point, no holding pressure is applied to compensate for shrinkage. During the process, the visible side 8 is embossed using a laser-etched contour in the injection mold. Vacuum holes in the embossed mold ensure particularly secure contact of the visible side 8 of the film composite 2 with the mold for reliable embossing. The film composite 2 can be trimmed by overcutting at a mold edge, or undercut slides can be used to create a fold.

[0027] By manufacturing the automotive component 1 using the described method, the component 1 can be produced particularly cost-effectively, exhibits a particularly distinctive and uniform grain pattern, and can be manufactured with exceptionally low carbon dioxide emissions, since no adhesive is used and the foamed support component 3 results in a particularly low weight. Within the framework of this method, the automotive component 1 is manufactured in a single process in which the film composite 2 is pre-formed in the injection mold using an in-mold graining process – including the fold – grained, back-injected, and trimmed. Thus, the finished automotive component 1 is manufactured in a so-called one-shot process.

[0028] The automotive component 1 features an in-mold graining texture on its surface, specifically on the visible side 8, for particularly good grain definition. This graining is created by laser-etched grains in the mold, which is a structure introduced by a laser device, and additional laser-etched vacuum holes in the mold. The foil composite 2 is drawn onto the structured surface of the mold through these holes. As an alternative to the mold with the laser-etched grain, electroplated shells or steel shells with an etched hub can be used for the graining. In this case, the steel shell can be milled and etched with the negative for the graining of the foil composite 2. The steel shell can also be provided with vacuum holes. The electroplated shells are typically made of nickel, which is inherently porous. Therefore, providing vacuum holes in the electroplated shells is unnecessary.A folded edge on automotive component 1 can be produced using undercut slides. This process enables the production of a smooth, high-quality surface in a single process step. This eliminates processes such as adhesive application, lamination, and folding. Consequently, factory space and carbon dioxide emissions are reduced.

[0029] To prevent shear wrinkles, a cascade filling process using a hot runner system with controlled needle movement speed is employed during injection molding. The particularly lightweight automotive component 1 produced using this process is also especially well-suited for recycling due to the minimal number of different materials used.

[0030] Overall, the invention shows what a manufacturing process for producing a soft-touch component using a one-shot injection molding process can look like. REFERENCE MARK LIST V1 to V7 respective process steps 1 motor vehicle component 2 foil composite 3 Support component 4 Top layer 5 foam layers 6 protective layer 7 Stacking direction 8 Viewing side 9 Back

Claims

[1] Method for producing a motor vehicle component (1), in which a multi-layer film composite (2) is back-injected with a plastic on its rear side (9), wherein the film composite (2) comprises a cover layer (4) which provides a visible side (8) of the motor vehicle component (1) opposite the rear side (9), an elastic foam layer (5) and a protective layer (6) which covers the foam layer (5) towards the rear side (9) and provides the rear side (9). [2] Method according to claim 1, characterized by that the film composite (2) is back-injected in a foam injection molding process. [3] Method according to claim 1 or 2, characterized by that the film composite (2) is back-injected by means of a hot runner system with controllable needle opening speed. [4] Method according to one of the preceding claims, characterized bythat a film composite (2) is back-injected, the cover layer (4) of which comprises a film made of a thermoplastic polyolefin. [5] Method according to one of the preceding claims, characterized by that the film composite (2) is thermoformed into a tool mold and then the thermoformed film composite (2) is back-injected. [6] Method according to claim 5, characterized by , that the cover layer (4) is provided with a grain embossing during thermoforming by the cover layer (4) is applied to the tool mold, the surface contour of which has the grain embossing to be introduced in negative, and is pulled onto the tool mold by means of a vacuum. [7] Motor vehicle component (1), with a film composite (2) which comprises a cover layer (4) which provides a visible side (8) of the motor vehicle component (1), an elastic foam layer (5) and a protective layer (6) which covers the foam layer (5) towards a rear side (9) opposite the visible side (8) and provides the rear side (9), wherein a carrier component (3) is injection-molded onto the film composite (2) on a rear side (9) opposite the visible side (8). [8] Motor vehicle component (1) according to claim 7, characterized by that the carrier component (3) is a foam component. [9] Motor vehicle component (1) according to claim 7 or 8, characterized bythat the film composite (2) comprises a cover layer (4) made of a thermoplastic polyolefin film providing the visible side (8) and / or an elastic foam layer (5) made of a polypropylene or a polyethylene and / or a protective layer (6) made of a thermoplastic polyolefin film providing the back side (9). [10] Motor vehicle component (1) according to one of claims 7 to 9, characterized by that the motor vehicle component (1) is designed as an interior component.

Images