Method for manufacturing a vehicle interior trim part and mold

Abstract

Method for manufacturing a vehicle interior trim part comprising the following steps: - Providing a forming tool (1) comprising a first forming tool element (2), a second forming tool element (3) and a slide (5, 5'), wherein a cavity (4) is formed between the first forming tool element (2) and the second forming tool element (3) and wherein the slide (5, 5') is slidably connected to the first forming tool element (2), - Arranging a decorative skin (7) with a visible side (8) of the decorative skin (7) on the first molding tool element (2) and arranging a carrier (9) on the second molding tool element (3) such that a cavity (13) is formed between the carrier (9) and a back side (12) of the decorative skin (7), - Introducing a foamable mixture (14) into the cavity (13), - Foaming of the mixture (14) such that a foam layer (24) is formed which fills the cavity (13), - Increasing the distance between the first molding tool element (2) and the second molding tool element (3) before and / or during foaming, so that the cavity (13) is enlarged, - Pressing the slider (5, 5') against a side of the decorative skin (7) facing away from the rear (12) during enlargement, such that the cavity (13) is sealed by pressing the decorative skin (7) with its rear (12) against a lateral surface (17) of the carrier (9) and / or against a lateral surface (18) of the second molding tool element (3), wherein the rear (12) of the decorative skin (7) slides along the lateral surface (17) of the carrier (9) and / or the lateral surface (18) of the second molding tool element (3) when the slider (5, 5') is pressed.

Description

[0001] The application relates to a method for manufacturing a vehicle interior trim part. Furthermore, the application relates to a mold for manufacturing a vehicle interior trim part according to the preamble of claim 7.

[0002] Methods for manufacturing vehicle interior trim parts comprising a cover layer, a substrate, and a foam layer arranged between the cover layer and the substrate are known from the prior art. For example, FR 2 979 569 A1 describes a method in which a mold is first provided, comprising a lower and an upper mold part. The previously manufactured cover layer is then placed on the lower mold part, and the previously manufactured substrate is attached to the upper mold part. The mold is typically designed such that the substrate and the cover layer are not in direct contact with each other in the resulting arrangement, so that a cavity is formed between the substrate and the cover layer.The upper mold part and the carrier can each have an opening through which a liquid foamable mixture can be poured into the cavity. The mixture is then allowed to fully foam and harden, forming the foam layer that fills the cavity and bonds the carrier to the surface layer. Typically, the volume of the foamable mixture increases five- to tenfold during foaming. As the foam layer forms, the lower mold part can be moved downwards relative to the upper mold part, increasing the height of the cavity during foaming. Finally, the completed interior trim panel can be removed from the mold.

[0003] The described method is suitable for manufacturing a vehicle interior trim panel with a thin foam layer that has a low foam density. This allows for a significant weight reduction in the vehicle interior trim panel.

[0004] However, inhomogeneities can occur in the foam layer if any air present in the cavity or any gaseous reaction products generated during foaming cannot reliably escape from the cavity. Further related prior art is described, for example, in publications JPH02 155 709A, US 4 793 784 A and US 5 500 169 A.

[0005] The purpose of this application is to propose a method suitable for the simple, fast, and cost-effective production of a lightweight vehicle interior trim component. Furthermore, it is an objective of this application to propose a suitably appropriate mold.

[0006] This problem is solved by a method with the features of the main claim and by a mold with the features of claim 7. Advantageous further developments result from the features of the dependent claims and the exemplary embodiments.

[0007] In the proposed method for manufacturing a vehicle interior trim component, a mold is first provided, comprising a first mold element, a second mold element, and a slide. A cavity is formed between the first and second mold elements. The slide is slidably connected to the first mold element. A decorative skin or layer is then applied to the first mold element with one visible side facing the first mold element, and a carrier is attached to the second mold element. This creates a cavity between the carrier and the back side of the decorative skin. A foamable mixture is then introduced into the cavity. In a further step, the mixture foams up to form a foam layer that fills the cavity.Before or during foaming, the distance between the first and second mold elements is increased, thus enlarging the cavity. During this enlargement, the slide is pressed against a side facing away from the back of the decorative skin, or against the visible side of the decorative skin, in such a way that the cavity is sealed. This occurs when the back of the decorative skin is pressed against a lateral surface of the substrate and / or a lateral surface of the second mold element, or when the back of the decorative skin at least partially touches and slides along the lateral surface of the substrate and / or the lateral surface of the second mold element.

[0008] Foaming typically involves a volume increase of the mixture, for example, a five- to tenfold increase. Furthermore, the viscosity of the mixture increases significantly during foaming. Because the distance between the mold components is smaller during filling, less air needs to escape from the cavity when the foamable mixture is introduced. The filling distance can be chosen so that the foamable mixture fills at least 50 percent or, for example, almost completely the cavity. Compared to manufacturing processes that use a fixed distance between the first and second mold components, a relatively low density of the foam layer can be achieved.In typical designs, the foam layer has a density of at most 200 g / l, preferably at most 150 g / l or at most 100 g / l.

[0009] This process allows for the production of a comparatively lightweight interior vehicle trim panel comprising the flat substrate, the foam layer, and the decorative skin, with the decorative skin being spaced apart from the substrate. The foam layer is positioned between the decorative skin and the substrate, bonded to both the substrate and the back of the decorative skin. This foam layer, located between the substrate and the decorative skin, creates an aesthetically pleasing, soft feel when a vehicle occupant touches the visible side of the decorative skin.

[0010] In typical designs, the cavity has a height of at least 2 mm, preferably at least 4 mm, and / or at most 15 mm, preferably at most 8 mm, after the mixture has been foamed. However, in undercut areas, the cavity can also have a height of at most 40 mm, preferably at most 20 mm, after the mixture has been foamed. The height of the cavity corresponds to the thickness of the foam layer to be produced.

[0011] The second mold element typically features an opening connected to the cavity for introducing or introducing the foamable mixture into the cavity. The mixture can be introduced using a known filling device, for example, a metering filling device.

[0012] Typically, the foamable or foaming mixture is introduced into the cavity in a liquid or low-viscosity state. This ensures that the foamable mixture is reliably distributed within the cavity, preventing unwanted localized compaction of the mixture during foaming and the formation of unwanted air pockets in the foam layer. It is typically intended that the foamable mixture is located on the reverse side of the decorative skin, away from the visible side, during or after its introduction into the cavity. The first mold element may be positioned below the second mold element. In this case, the liquid foamable mixture can spread across the reverse side of the decorative skin due to gravity.Additionally or alternatively, the liquid foamable mixture can spread on the back of the decorative skin as a result of filling pressure.

[0013] The foamable mixture is typically a reactive mixture, such as a foamable polymer. The mixture may, for example, contain several chemical compounds that react with each other to produce gases that cause foaming. In this case, the mixture could be, for instance, a polyurethane mixture. This could contain, for example, at least one isocyanate, at least one polyol, and water. A reaction between the isocyanate and the polyol can lead to the formation of the polyurethane, while a reaction between the isocyanate and the water releases carbon dioxide.

[0014] The visible side of the decorative skin does not need to be visible at all times and in all areas. The term "visible side" simply means that this side of the decorative skin faces the vehicle interior when the interior trim panel is used as intended.

[0015] The application also relates to a mold for manufacturing the vehicle interior trim part with the decorative skin, the carrier, and the foam layer arranged between the decorative skin and the carrier. The mold comprises the first mold element and the second mold element, with the cavity formed between the first and second mold elements. The carrier can be arranged or attached to the second mold element, and the decorative skin can be positioned on the first mold element with its visible side facing down, such that the cavity is formed between the carrier and the back of the decorative skin. The foamable mixture can be introduced into the cavity, and the second mold element is movable relative to the first mold element so that the cavity can be enlarged before and / or during the foaming of the foamable mixture.Furthermore, the mold includes at least one slide that is slidably connected to the first mold element. The slide is designed to press against the side of the decorative skin facing away from the back, or the visible side of the decorative skin, during movement of the second mold element relative to the first mold element, in such a way that the cavity is sealed by pressing the decorative skin with its back side against the lateral surface of the substrate and / or against the lateral surface of the second mold element.

[0016] The proposed method and mold ensure that the cavity is reliably sealed by pressing the slide against the decorative skin. In particular, the cavity can be reliably sealed even as the gap increases. This prevents, for example, foam from escaping the cavity due to volume expansion during foaming. Therefore, the proposed method and mold allow for material savings in the production of vehicle interior trim parts, as a smaller quantity of the foamable mixture can be used. Furthermore, an additional processing step, namely the removal of any foam that may have escaped from the cavity, is eliminated.

[0017] A further advantage of the method, or rather the mold, is that it allows the cavity to be sealed while increasing the distance between the first and second mold elements, provided the decorative skin lies flat against the second mold element. This advantage is not achieved with typical known methods, such as the one described in German publication FR 2 979 569 A1. In the known method, the surface layer necessarily ripples in the edge regions of the cavity if the lower and upper mold parts are close together. Only when the height of the cavity is increased does the surface layer lie flat against the lower mold part. This rippling of the surface layer can negatively affect the quality of the foam layer being formed.

[0018] In the proposed method, the decorative skin is typically positioned with an edge region of the decorative skin between the slide and the lateral surface of the carrier and / or the lateral surface of the second mold element after the decorative skin has been positioned on the first mold element. A direction in one plane of the edge region of the decorative skin generally runs substantially parallel to a direction of movement of the second mold element relative to the first mold element when the slide presses against the decorative skin.

[0019] The slide can be moved, for example, electrically, hydraulically, or pneumatically. In typical designs, the slide pushes in a direction that is essentially perpendicular to the direction of movement of the second mold element relative to the first mold element as the distance increases.

[0020] When the slider is pressed, the back of the decorative skin slides along the side surface of the carrier and / or the side surface of the second molding tool element.

[0021] Multiple sliding gates can, of course, be provided. These are typically arranged in positions around the sides of the cavity. The sliding gates then typically press inwards to seal the cavity. In addition to the sliding gate(s), further sealing elements, which may be elastically deformable, can be provided around the cavity.

[0022] A surface of the slider that comes into contact with the decorative skin when the slider is pressed against the side facing away from the back, or the visible side of the decorative skin, may have raised areas to increase static friction between the decorative skin and the slider. These raised areas may be in the form of prongs or roughened surfaces. Typically, this increases the static friction between the side facing away from the back of the decorative skin, or between the visible side of the decorative skin and the slider, to such an extent that it is greater than the friction between the back of the decorative skin and the lateral surface of the second mold element and / or the carrier. This prevents the decorative skin from shifting due to adhesion to the lateral surface of the second mold element and / or the carrier as the distance between the first and second mold elements increases.

[0023] Typically, the distance between the first molding tool element and the second molding tool element is increased before or during foaming until a resulting height of the cavity corresponds to the thickness of the foam layer to be produced.

[0024] In some designs, the decorative skin may be pressed against the side surface of the carrier, rather than against the side surface of the second mold element, by the slider once the desired height is reached. This is typically achieved by selecting an appropriate size and positioning of the decorative skin on the first mold element. In this case, the sealing effect is provided by the edge of the decorative skin, eliminating the need to remove any protruding areas of the decorative skin, for example, by punching, after the foam layer has formed. This eliminates a production step in the vehicle interior trim panel and also results in material savings.

[0025] The proposed method and mold allow for controlled venting of the cavity in addition to the sealing described above. For example, the cavity can be vented during the introduction of the foamable mixture. This is achieved by moving the slide valve to a retracted position or leaving it in this position. This allows air or gaseous reaction products to escape through a gap or gas-permeable channel that may be formed between the back of the decorative skin and the second mold part or the carrier.

[0026] The decorative skin is typically a slush-formed skin. This can be produced in a visually appealing and relatively inexpensive manner using established methods. However, in other versions, the decorative skin can also be formed by a different layer known from the prior art, for example, a different type of plastic layer (PU spray skin, thermoforming film, IMG film) or a leather layer. The substrate can, for example, be an injection-molded plastic part.

[0027] The features mentioned above regarding the method for manufacturing the vehicle interior trim part can be transferred to the mold for manufacturing the vehicle interior trim part. Furthermore, the features mentioned above regarding the mold for manufacturing the vehicle interior trim part can be transferred to the method for manufacturing the vehicle interior trim part.

[0028] An exemplary embodiment is described below with reference to the illustrations. They show Fig. 1 a forming tool, Fig. 2 a schematic view during a process step in the manufacture of a vehicle interior trim part, Fig. 3 a schematic view during a further process step in the manufacture of the vehicle interior trim part, Fig. 4. An enlarged view of an area in Fig. 3, Fig. 5 a schematic view during a further process step in the manufacture of the vehicle interior trim part, Fig. 6. An enlarged view of an area in Fig. 5 and Fig. 7 a schematic view during a further process step in the manufacture of the vehicle interior trim part.

[0029] In Fig. Figure 1 shows a forming tool 1. The forming tool 1 comprises a first forming tool element 2 and a second forming tool element 3. A cavity 4 is formed between the first forming tool element 2 and the second forming tool element 3. The cavity 4 is bounded on a top side by the second forming tool element 3 and on a bottom side by the first forming tool element 2.

[0030] Furthermore, the mold 1 comprises two slides 5, 5', each slidably connected to the first mold element 2. The slides 5, 5' laterally delimit the cavity 4 and, in the illustrated embodiment, are linearly displaceable to the left and right, respectively. The movement of the slides 5, 5' can be driven, for example, by an electric motor (not shown).

[0031] Additionally, the second mold tool element 3 can be moved upwards or downwards relative to the first mold tool element 2, so that the height of the cavity 4 can be increased by moving the second mold tool element 3 upwards.

[0032] The second mold element 3 has a central opening 6, which is provided for introducing a foamable mixture into the cavity 4. For this purpose, a filling device (not shown) can be connected to the second mold element 3 in the area of ​​the opening 6.

[0033] In Fig. Figure 2 shows a process step in the manufacture of a vehicle interior trim part. Recurring features are identified by the same reference numerals in this and the following figures. Here, a decorative skin 7 was arranged on the first mold element 2 such that a visible side 8 of the decorative skin 7 faces the first mold element 2. The decorative skin 7 is, for example, a slush-molded skin.

[0034] Furthermore, a support 9 was attached to the second mold element 3. The support 9 extends horizontally and is manufactured as an injection-molded plastic part. The support 9 has an opening 10 in a central area. The support 9 is designed and positioned such that the opening 10 of the support 9 overlaps with the opening 6 of the second mold element 3.

[0035] The carrier 9 and the decorative skin 7 do not completely fill the cavity 4. Instead, a bottom surface 11 of the carrier 9 and a back surface 12 of the decorative skin 7 are spaced apart from each other, so that a cavity 13 is formed between the carrier 9 and the decorative skin 7.

[0036] A further process step in the manufacture of the vehicle interior trim part is in Fig. Figure 3 illustrates the process. To form a foam layer, a liquid foamable mixture 14 is first injected from above into the cavity 13 between the carrier 9 and the decorative skin 7 via the filling device through the opening 6 of the second mold element 3 and through the opening 10 of the carrier 9. Due to gravity and / or injection pressure, the liquid foamable mixture 14 spreads across the back surface 12 of the decorative skin 7 and fills approximately 65 percent of the volume of the cavity 13. The foamable mixture 14 is, for example, a reactive foamable polymer designed to react to form polyurethane.

[0037] During the filling of the foamable mixture 14 into the cavity 13, the slides 5, 5' are in an open or retracted position, i.e. the left slide 5 is moved to the left and the right slide 5' is moved to the right.

[0038] Fig. Figure 4 shows an enlarged view of an area labelled with reference numeral 15 of the in Fig. The arrangement shown in Figure 3 is as follows. The decorative skin 7 was positioned on the first mold element 2 such that the decorative skin 7 is oriented almost vertically in an edge region 16. The edge region 16 of the decorative skin 7 is laterally surrounded by the slide 5' and a lateral surface 17 of the carrier 9, as well as a lateral surface 18 of the second mold element 3.

[0039] The visible side 8, or the side of the decorative skin 7 facing away from the reverse side 12, rests in some areas against a surface 19 of the slide 5'. This surface 19 of the slide has raised areas, two of which are marked by reference numerals 20 and 20' as examples.

[0040] A gap 21 is formed between the back 12 of the decorative skin 7 and the side surface 17 of the carrier 9 or the side surface 18 of the second mold element 13. When the foamable mixture 14 is poured into the cavity 13, air escapes from the cavity 13 through the gap 21.

[0041] After a desired quantity of the foamable mixture 14 has been poured into the cavity 13, the slides 5, 5' are moved inwards, as shown in Fig. 5 is indicated by the arrows marked with the reference symbols 22 and 22' respectively.

[0042] An enlarged view of the in Fig. 5, the area marked with reference numeral 23, is in Fig. Figure 6 illustrates this. By moving the slider 5', the edge region 16 of the decorative skin 7 is pressed to the left. This presses the decorative skin 7, with its back side 12, against the lateral surface 17 of the carrier 9 and against the lateral surface 18 of the second mold element 13 in the edge region 16. This closes the gap 21 and seals the cavity 13.

[0043] In a further process step, the previously liquid foamable mixture 14 foams up. During foaming, the second mold element 3, together with the carrier 9, is moved upwards, thus enlarging the cavity 4 and the void 13. It is also possible for the second mold element 3, together with the carrier 9, to be moved upwards before foaming. During foaming, the slides 5, 5' remain in the Fig. Position 6 shown, so that the cavity 13 remains sealed.

[0044] Fig.Figure 7 shows the arrangement at a point in time after the second mold element 3 has been moved upwards in the direction of the arrow with reference numeral 25. The cavity 4 is thus enlarged until the height of the cavity 13 corresponds to the desired thickness of a foam layer 24 to be produced. In this arrangement, the back side 12 of the decorative skin 7 is pressed only against the lateral surface 17 of the carrier 9, but not against the lateral surface 18 of the second mold element 3.

[0045] The foaming process transforms the previously liquid, foamable mixture 14 into a foam layer 24. During foaming, the volume of the mixture 14 increases, so that in the illustrated example, the foam layer 24 completely fills the cavity 13. During foaming, the foam layer 24 bonds to the underside 11 of the carrier 9 and to the back side 12 of the decorative skin 7. The increase in volume of the mixture is accompanied by a decrease in its density, resulting in a comparatively low density of, for example, less than 150 g / l for the foam layer 24.

[0046] As the distance between the first mold element 2 and the second mold element 3 increases, the back side 12 of the decorative skin 7 slides along the edge region 16 of the decorative skin 7 on the lateral surface 17 of the carrier 9 and on the lateral surface 18 of the second mold element 3, with the lateral surfaces 17, 18 moving upwards. The raised areas 20, 20' on the surface 19 of the slide 5' generate sufficient static friction between the slide 5' and the decorative skin 7, so that the latter does not move relative to the slide 5' or moves only to a minimal extent.

[0047] In a further step, the finished vehicle interior trim part, which includes the decorative skin 7, the foam layer 24 and the carrier 9, can be removed from the molding tool 1.

[0048] Only features of the various embodiments disclosed in the exemplary embodiments can be combined and claimed individually.

Claims

[1] Method for manufacturing a vehicle interior trim part comprising the steps: - Providing a forming tool (1) comprising a first forming tool element (2), a second forming tool element (3) and a slide (5, 5'), wherein a cavity (4) is formed between the first forming tool element (2) and the second forming tool element (3) and wherein the slide (5, 5') is slidably connected to the first forming tool element (2), - Arranging a decorative skin (7) with a visible side (8) of the decorative skin (7) on the first molding tool element (2) and arranging a carrier (9) on the second molding tool element (3) such that a cavity (13) is formed between the carrier (9) and a back side (12) of the decorative skin (7), - Introducing a foamable mixture (14) into the cavity (13), - Foaming of the mixture (14) such that a foam layer (24) is formed which fills the cavity (13), - Increasing the distance between the first molding tool element (2) and the second molding tool element (3) before and / or during foaming, so that the cavity (13) is enlarged, - Pressing the slider (5, 5') against a side of the decorative skin (7) facing away from the rear (12) during enlargement, such that the cavity (13) is sealed by pressing the decorative skin (7) with its rear (12) against a lateral surface (17) of the carrier (9) and / or against a lateral surface (18) of the second molding tool element (3), wherein the rear (12) of the decorative skin (7) slides along the lateral surface (17) of the carrier (9) and / or the lateral surface (18) of the second molding tool element (3) when the slider (5, 5') is pressed. [2] Method according to claim 1, characterized by, that the slider (5, 5') pushes in a direction (22, 22') which is oriented essentially perpendicular to a direction of movement (25) of the second molding tool element (3) relative to the first molding tool element (2) during the enlargement of the distance. [3] Method according to one of claims 1 or 2, characterized by , that when the slider (5, 5') is pressed against the side of the decorative skin (7) facing away from the rear (12) the surface (19) of the slider (5, 5') which is in contact with the decorative skin (7) has elevations (20, 20') to increase static friction between the decorative skin (7) and the slider (5, 5'). [4] Method according to any one of claims 1 to 3, characterized by , that the distance between the first molding tool element (2) and the second molding tool element (3) is increased during foaming until a resulting height of the cavity (13) corresponds to a thickness of the foam layer (24) to be produced. [5] Method according to claim 4, characterized by , that the decorative skin (7) with its back side (12) is pressed by the slider (5, 5') against the side surface (17) of the carrier (9) and not against the side surface (18) of the second molding tool element (3) as soon as the resulting height is reached. [6] Method according to any one of claims 1 to 5, characterized by the step: - Venting the cavity (13) during the introduction of the foamable mixture (14) into the cavity (13) by moving the slide (5, 5') into a retracted position or leaving it in a retracted position. [7] Molding tool (1) for producing a vehicle interior trim part with a decorative skin (7), a carrier (9) and a foam layer (24) arranged between the decorative skin (7) and the carrier (9), comprising a first molding tool element (2) and a second molding tool element (3), wherein a cavity (4) is formed between the first molding tool element (2) and the second molding tool element (3), wherein the carrier (9) can be arranged on the second molding tool element (3) and the decorative skin (7) with a visible side (8) can be arranged on the first molding tool element (2), such that a cavity (13) is formed between the carrier (9) and a rear side (12) of the decorative skin (7), wherein a foamable mixture (14) can be introduced into the cavity (13) and wherein the second molding tool element (3) is movable relative to the first molding tool element (2),that the cavity (13) can be enlarged before and / or during foaming of the foamable mixture (14), characterized by at least one slide (5, 5') which is slidably connected to the first mold element (2), wherein the slide (5, 5') is configured to press against a side of the decorative skin (7) facing away from the rear (12) during movement of the second mold element (3) relative to the first mold element (2) such that the cavity (13) is sealed by pressing the decorative skin (7) with its rear (12) against a lateral surface (17) of the carrier (9) and / or against a lateral surface (18) of the second mold element (3), wherein the mold (1) is configured such that the rear (12) of the decorative skin (7) slides along the lateral surface (17) of the carrier (9) and / or the lateral surface (18) of the second mold element (3) when the slide (5, 5') is pressed. [8] Forming tool (1) according to claim 7, characterized by , that the slider (5, 5') has a surface (19) with elevations (20, 20') to increase static friction between the decorative skin (7) and the slider (5, 5') when the slider (5, 5') is pressed against the side of the decorative skin (7) facing away from the rear (12). [9] Forming tool (1) according to one of claims 7 or 8, characterized by , that the second molding tool element (3) has an opening (6) connected to the cavity (4) for introducing the foamable mixture (14) into the cavity (13). [10] Forming tool (1) according to any one of claims 7 to 9, characterized by , that the slide (5, 5') is arranged to push in a direction (22, 22') which is oriented essentially perpendicular to a direction of movement (25) of the second molding tool element (3) relative to the first molding tool element (2) during an enlargement of the cavity (13).

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