Method of manufacturing a vehicle interior trim part and part obtained

Abstract

Method for manufacturing a vehicle interior trim part and part obtained The present invention relates to a method for manufacturing a vehicle interior trim part (1), with a visible composite coating layer (2) and a rear support layer (3), the composite coating layer (2) comprising a surface layer (4), an elastically compressible comfort layer (5) and, optionally, a functional or technical purpose layer (6), said method consisting of producing at least in the surface layer (4) portions of seam lines (7) and / or local, in particular point, topstitching (7').Method characterized in that it consists in providing a comfort layer (5) comprising at least a first underlayer (8) and at least a second underlayer (9), and in that it consists in producing said portions of stitching lines (7) and / or topstitching (7') in such a way that they pass through at least the surface layer (4) and the comfort layer (5), and that they cause localized compressions of said at least two constituent components (8 and 9), these compressions resulting in indentations (10) and in a hollow and bump configuration. Figure to be published with the abstract: Fig. 3.

Description

Title of the invention: Method for manufacturing an interior vehicle trim part and part obtained

[0001] The present invention relates to the field of vehicle interior equipment, and more particularly to the coverings of the trim parts of the interior of vehicles, such as for example dashboard, door panel, central console, door pillar and windows, and their sub-components (opening flaps, armrests, strips, medallions, etc.) with a particular decorative effect sought, giving a "quilted" or "padded" effect. Such an effect gives an aesthetic appearance and a particular style, in addition to providing a luxurious and comfortable impression, and it improves the perceived quality of the coated parts.

[0002] The subject of the invention is a method of manufacturing such a part, as well as the resulting part.

[0003] The state of the art in this field (see for example: JP 2015143067) consists essentially of solutions often implemented in the production of automobile seats. These generally include the production of a foamed form in PU (Polyurethane), fixed on a chassis or a metal structure and on which a textile cover or envelope is fitted with a textile covering comprising a foam as a laminated underlayer, and assembly or decorative stitching.

[0004] However, this is not enough to create the desired quality “quilted” effect and the cost of producing this known solution is very high. Furthermore, this known solution is not suitable for coating substrates, particularly those made of hard and rigid plastic material, which may have any shape, concave and / or convex.

[0005] Methods are also known for producing parts with a “quilted” surface effect, which are more suited to the type of parts referred to herein.

[0006] These manufacturing methods result in the production of a vehicle interior trim or covering part comprising a visible composite covering layer and a rear support layer, assembled together. Such a method essentially consists of providing a composite covering layer comprising a surface or appearance layer, in particular of the skin or textile type, an elastically compressible comfort layer and, optionally, a functional or technical purpose layer, and assembling, then adding or overmolding the support layer with or onto the covering layer at the face of the latter opposite the surface or appearance layer. Said method also consists of producing at least in the surface layer, and optionally in a portion of the comfort layer, portions of sewing lines and / or local topstitching, particularly punctual.

[0007] Nevertheless, the orthogonal feel resulting from the implementation of these known processes is not sufficiently enhanced and does not give the part a feeling of comfort that optimally meets the expectations of users, particularly at the top of the range.

[0008] Furthermore, there is a demand for a solution designed to: - that the technique for producing the quilting is compatible with existing techniques for producing such vehicle interior trim parts. - that the seams or topstitching making up the quilting, visible or not, follow a sought-after and aesthetic pattern, in continuous or discontinuous lines, therefore resulting from continuous or successive and interrupted sewing operations. - that these seams or stitching are placed judiciously and in a sophisticated and aesthetic manner in relation to the shape of the substrate to be coated and the shape of the part to be obtained. - be able to ensure possible alignment and / or harmony with any seams or topstitching of neighboring pieces. - to be able to decline quilted coverings with seams or stitching, in traditional covering without seams, for parts of lower level vehicles, without impact on tools and without additional cost.

[0009] The present invention aims to meet at least certain points of the request expressed above while avoiding the aforementioned drawbacks.

[0010] For this purpose, it relates to a method for manufacturing a vehicle interior trim or covering part, said part comprising a visible composite covering layer and a rear support layer, assembled together, said method consisting of providing a composite covering layer comprising a flexible surface or appearance layer, in particular of the skin or textile type, an elastically compressible comfort layer and, optionally, a functional or technical purpose layer, and assembling the support layer with the covering layer at the face of the latter opposite the surface or appearance layer, either by sheathing or adhesive or material bonding, or by overmolding the support layer onto the surface or appearance layer, said method also consisting of producing at least in the surface layer portions of seam lines and / or local, in particular point, topstitching,method characterized in that it consists in providing a comfort layer comprising at least two constituent components, namely, at least a first underlayer and at least a second underlayer, this second underlayer being thicker and composed of a material more elastically resistant to compression than the first underlayer, and in that it consists in producing said portions of lines of, sewing and / or stitching in such a way that they pass through at least the surface layer and the comfort layer, and possibly the functional layer, or even where appropriate the support layer, and that they cause localized compressions of said at least two constituent components, these compressions resulting in corresponding indentations at the level of the external face of the covering layer and in local deformations of the surface or flexible appearance layer resulting in a configuration of hollows and bumps.

[0011] The invention will be better understood from the following description, which relates to preferred embodiments, given as non-limiting examples, and explained with reference to the appended schematic drawings, in which:

[0012] [Fig-1] is a partial top view of a piece of trim or covering comprising topstitching and presenting the desired “quilted” or “padded” effect;

[0013] [Fig.2] is a partial perspective view of a piece of trim or covering including portions of seams and presenting the desired “quilted” or “padded” effect;

[0014] [Fig.3] is a detailed sectional view, transverse to a seam and along AA, of the part shown in [Fig.2], in accordance with a first embodiment of the invention;

[0015] [Fig.4A],

[0016] [Fig.4B],

[0017] [Fig.4C] and

[0018] [Fig.4D] illustrate, by partial sectional views along AA and in four successive operating stages, the preliminary production of the complex coating layer forming part of the part, in accordance with the first embodiment of the method according to the invention;

[0019] [Fig.5A],

[0020] [Fig.5B] and

[0021] [Fig.5C] illustrate, by sectional views along AA and in three successive operating stages, the production of a covering or trim part, in accordance with a second embodiment of the method according to the invention;

[0022] [Fig.6A],

[0023] [Fig.6B],

[0024] [Fig.6C], and

[0025] [Fig.6D] illustrate, by sectional views along AA and in four successive operating stages, the production of a covering or trim part, in accordance with a third embodiment of the method according to the invention;

[0026] [Fig.7A] and

[0027] [Fig.7B] are sectional views of two other variant embodiments of a support layer, intended to be assembled with a complex covering layer according to the invention to constitute a cladding or trim part;

[0028] [Fig.8A] and

[0029] [Fig.8B] illustrate in two stages, and in the form of partial sectional views, the assembly of a prepared complex coating layer with a support layer such as that shown in [Fig.7A]

[0030] [Fig.9A],

[0031] [Fig.9B],

[0032] [Fig.9C] and

[0033] [Fig.9D] are partial sectional views illustrating different methods of preparing a complex coating layer according to the invention with a view to its assembly with a part support as shown in [Fig.7A] and figures 8;

[0034] [Fig. 10] is a partial sectional view similar to that of [Fig. 3], according to another variant embodiment (with a transparent protective layer on the surface), and,

[0035] [Fig. 11] is a simplified sectional view of a mold device for carrying out the assembly phase of the coating and support layers of a part according to the invention.

[0036] The invention relates to a method for manufacturing a part (1) of vehicle interior trim or decoration.

[0037] Such a part (1) comprises, as shown in figures 1 to 3, 8 and 10, an apparent composite coating layer (2) and a rear support layer (3), assembled together.

[0038] Said method essentially consists in providing a composite covering layer (2) comprising a flexible surface or appearance layer (4), in particular of the skin or textile type, an elastically compressible comfort layer (5) and, optionally, a functional or technical purpose layer (6), then in assembling the support layer (3) with this covering layer (2) - or vice versa - at the level of the face of the latter opposite the surface or appearance layer (4), either by sheathing or adhesive or material bonding, or by overmolding said support layer (3) onto the surface or appearance layer (4). This method also consists in producing at least in the surface layer (4) portions of seam lines (7) and / or local, in particular point, topstitching (7') to give a particular appearance.

[0039] According to the invention, this method also consists of:

[0040] - to provide a comfort layer (5) comprising at least two components constituents, namely, at least a first sub-layer (8) and at least a second sub-layer (9), this second sub-layer (9) being thicker and composed of a material more elastically resistant to compression than the first undercoat (8), and

[0041] - to produce said portions of sewing lines (7) and / or topstitching (7') in such a way such that they pass through at least the surface layer (4) and the comfort layer (5), and possibly the functional layer (6), or even where appropriate also the support layer (3), and that they cause localized compressions of said at least two constituent components (8 and 9), these compressions resulting in corresponding recesses (10) at the level of the external face of the covering layer (2) and in local deformations of the surface or flexible appearance layer (4) resulting in a configuration of hollows and bumps.

[0042] Thus, the “quilted” or “padded” rendering is not only visual or superficial, but also physical and volumetric, with a rendering in terms of touch which is pleasant and which presents a resistance which increases progressively with the degree or level of compression (the more one compresses, the greater the resistance). In addition, the depth of the local indentations and the protuberance of the zones not compressed by the seams and stitching are particularly important, providing a very contrasting topography with these two types of structures succeeding one another continuously on the surface, on the visible face of the piece. This results in a plush and comfortable impression, as well as a notable improvement in the perceived quality of the pieces (1).

[0043] The surface layer (4) may for example consist either of a skin, possibly lined on its non-visible face by a backing such as a grid, a textile, a film, a non-woven fabric, or of a textile material.

[0044] In accordance with an advantageous constructive variant of the invention, it may be provided to provide a first sub-layer (8) made of a material of the cellular or foamed type and a second sub-layer (9) made of a material composed of a multitude of elongated flexible elements (9') mutually juxtaposed and oriented in a direction substantially perpendicular to the median plane of said sub-layer (9) in the absence of stress, so as to form a compressible layer, with a compressive strength determined in the aforementioned direction.

[0045] The first underlayer (8) is made of a first comfort material, for example a polyurethane (PU), polypropylene (PP), polyethylene terephthalate (PET) or polyester (PE) foam, with a thickness of 1 to 10 mm (preferably 2 mm to 5 mm), and a density of between 20 and 50 kg / m3 (preferably between 35 and 45 kg / m3).

[0046] The second underlayer (9) is made of a second comfort material, firmer than that of the underlayer (8), at least in the direction perpendicular to the surface of the covering layer (2). It may for example consist of a layer of 3D mesh material, such as a knitted textile of the 3D Raschel type or a felt, made of PE, with a thickness of 1 to 10 mm (preferably 5 mm to 8 mm), and a grammage between 100 and 1000 g / m2 (preferably between 500 and 800 g / m2).

[0047] In accordance with a first variant, it may be provided to provide a functional layer (6) also crossed by said portions of seam lines (7) and / or topstitching (7'), this layer (6) serving as an assembly interface between the composite coating layer (2) and the support layer (3), and also as a rear, tensile-resistant bonding layer for said portions of seam lines (7) and / or topstitching (7').

[0048] The functional layer (6) preferably corresponds to a technical textile backing, for example a non-woven fabric made of PET or PP, or a mixture of these materials, with a thickness of 0.5 to 2 mm (preferably 0.8 mm to 1.5 mm, and advantageously approximately 1.0 mm), and a weight of between 30 and 200 g / m2 (preferably between 50 and 80 g / m2). This layer, which serves as a rear attachment surface for the stitches (7) and the topstitching (7'), may, if necessary, be thermoformed to avoid excessive local deformation and to reduce or eliminate the gap (17) resulting between the layers (2 and 3). This gap may also be reduced by pressure during sheathing or by an element of the mold during overmolding of the layer (3). It also advantageously serves as a bonding layer for the support layer (3) secured by gluing or overmolding.In particular, during such overmolding of the support layer (by injection of plastic resin or by assembly by thermocompression of a felt-mixture of natural fibers and PP fibers for example), the layer (6) ensures cohesion and joining between the layers to be connected (2 and 3), by mechanical and / or thermal attachment and / or by penetration or imprisonment in the material of said support layer (3).

[0049] In an alternative embodiment not shown and not implementing a functional layer (6), it may be provided that the elongated flexible elements (9') are at least partly, preferably entirely, formed in one piece and from the material constituting the support layer (3).

[0050] According to a first embodiment, illustrated by figures 4 and figures 3, 8 and 10 (for the last step), the manufacturing method essentially consists of first assembling (after pre-cutting them to the correct dimensions) the different layers (4, 5, 6) forming the composite covering layer (2), then producing the portions of seam lines (7) and / or the topstitching (7') according to a predetermined implantation pattern (with generation of the corresponding recesses) and finally assembling the support layer (3) with said composite covering layer (2), or forming it on the latter, at the level of the functional or technical purpose layer (6) when it is present.

[0051] The assembly of the components (8 and 9) of the comfort layer (5) and the assembly of the latter with the appearance and functional layers (4 and 6) can be carried out in different ways known to those skilled in the art, namely, for example: counter-gluing with a polyurethane or other glue, use of a thermoadhesive veil or a double-sided adhesive, surface fusion of the first underlayer (8) to produce a sticky material (complexing by flame) or the like, these different solutions being able to be mixed.

[0052] According to a second embodiment, illustrated by two illustrative variants in Figures 5 and 6, the manufacturing method essentially consists of first assembling the layers (4, 5, 6) to form the composite covering layer (2), then assembling the latter with the support layer (3), and then producing the seam line portions (7) and / or the topstitching (7') according to a predetermined implantation pattern, the latter (7, 7') also passing through said support layer (3).

[0053] According to a third embodiment, the manufacturing method may also consist of superimposing the different layers (4, 5, 6) forming the composite covering layer (2), possibly after cutting to the correct dimensions, and assembling these layers (4, 5, 6) together and simultaneously with the support layer (3) when producing the portions of seam lines (7) and / or the topstitching (7') following a predetermined implantation pattern and crossing these different layers, a pre-assembly by stapling or nailing being able to be carried out if necessary.

[0054] In accordance with an advantageous variant of practical implementation of the invention, it may be provided to secure, by gluing or sheathing for example, the different layers (4, 5, 6) forming the composite covering layer (2), where appropriate pre-assembled in a pre-formed composite covering layer (2), with the support layer (3), this securing being carried out in a mold (11) having a cavity (11') of a shape adapted to that of the part (1), and using a means (12) for applying said layers against said support layer (3), which provides a pressure distributed surface-wise in a substantially uniform manner, positive or negative, for example by vacuum suction or by positioning and inflating an inflatable sheathing pocket or membrane (see [Fig. 11]).

[0055] Of course, the formation of a recess (10) can be concomitant with the creation of a seam or a topstitch.

[0056] Alternatively and according to another embodiment, illustrated in Figures 5B, 6B and 6C, it may also be provided to carry out a preforming or pre-deformation operation of the composite coating layer (2) to generate a recess (10) at the locations of the portions of seam lines (7) and / or the stitches (7'), before their production, for example by the action of a tool (16), possibly hot, or by placing a retention element (16'), such as nailing or stapling, or by combined implementation of these two operations.

[0057] In accordance with a first variant, emerging from figures 6, the method may consist in subjecting the composite coating layer (2), before or after its assembly with the support layer (3), to a hot embossing operation so as to create a pattern printed in the thickness of said coating layer (2), defining at least for some the locations of the local seams made in a subsequent operation. During this embossing operation, points or lines of dummy stitching points may also be formed, at the same locations as the recesses intended to receive the portions of stitching lines (7) and / or the stitches (7'), and / or at different locations.

[0058] More specifically, and with a view to offering wider possibilities for particular visual renderings, the method may also consist of subjecting the composite coating layer (2), before or after its assembly with the support layer (3), or at least the surface or appearance layer (4), to a printing operation aimed at creating a relief pattern imitating sewing lines or topstitching, at least some of these reliefs being completed, during a subsequent operation, by the production of portions of sewing lines (7) and / or real local topstitching (7').

[0059] In the other variant illustrated in Figures 5 as an example, the staple (16) which is anchored in the support layer (3) can temporarily or permanently contribute to the creation of the recess (10). It also constitutes a marking for the subsequent creation of the portions of seam lines (7) and / or the topstitching (7').

[0060] In order to be able to guarantee edges (1') of parts (1) with a high finishing quality and small radii of curvature, in accordance with market demand, the invention provides for providing a covering layer (2) with a comfort layer (5) having a reduced thickness along at least one of the edges (2') of said covering layer (2) intended to form an edge (1') of the part (1), this reduced thickness being obtained by total or partial removal of the second sub-layer (9), or removal of at least part of the thickness of the latter, or even where appropriate of the first sub-layer (8), the resulting strip of reduced thickness (5') of the comfort layer (5) being folded over or folded over the corresponding edge (3') of said support layer (3).

[0061] The reduction in thickness can be carried out in different ways (for example: adapted pre-cutting, cutting, milling or melting of the second sub-layer) and affect only part or all of the second sub-layer (9), or even where appropriate the first sub-layer (8), as shown in Figures 9.

[0062] To avoid, in the context of the reduction of the thickness of the aforementioned layer (5), a sagging at the edge (1'), it may be provided to provide a support layer (3) with at least one edge (3') having a peripheral rim (3”) in the form of a wing or a rib in one piece and with a rounded edge (13) and / or a body of curved shape in section (see figures 7A and 7B) and to fold down or to re-edge (see figures 8A and 8B) a corresponding lateral edge strip (2') of said covering layer (2) around said rim (3”), preferably an edge strip (2') thinned in thickness over a width determined by partial or total removal or suppression of the second underlayer (9), and where appropriate of the first underlayer (8), to form an edge (1') of the part (1).

[0063] Preferably, and in order to avoid obtaining protruding and hard edges which could constitute risk areas for passengers, especially at the level of contact surfaces with these passengers during impacts (accidents), it is provided to provide a peripheral rim (3”) in the form of an outwardly curved and elastically deformable peripheral wing, with an end edge (13) in the form of a current terminal thickening, a second wing (14) intended for fixing the folded edge (2') of the covering layer (2) being possibly formed opposite the rim (3”).

[0064] In order to achieve a precise assembly between the coating and support layers, it may be provided to provide a support layer (3) provided with positioning means and / or indexing marks and to use these means and / or marks during the operation of assembling the coating layer (2) with this support layer (3).

[0065] Furthermore, to obtain precise and repetitive location of the portions of sewing lines (7) and / or topstitching (7') on the covering layer (2), use may be made, for example, depending on the manufacturing method and means used, of a positioning template system, a laser projection system, a preprogrammed sewing robot or the like.

[0066] Within the scope of the invention, it may also be provided to manufacture several parts (1) of different shapes and intended to dress or cover distinct locations in the interior of a vehicle, these parts (1) being configured, in terms of distribution of the recesses (10) and the portions of sewing lines (7) and / or the local topstitching (7'), to provide a set of parts (1) producing by mutual juxtaposition, in the assembled state, an interior trim with a substantially homogeneous pattern. Such a possibility makes it possible to ensure alignment between the patterns of adjacent parts and / or overall harmony between the renderings of the different parts (1) forming the trim.

[0067] It is also noted that the particular steps of the method according to the invention are harmoniously integrated, as a selectable alternative, into a method of manufacturing parts (1) without recesses (10), nor seams or stitching.

[0068] In the event of a search for a particular visual rendering and / or additional protection, it may also be envisaged to apply, over the surface layer (4) or in appearance, an additional layer (15) of protection and / or decoration, of an opaque, transparent or translucent nature, for example by applying it by thermo-sheathing or simple sheathing (see [Fig. 10]).

[0069] The invention also relates to a part (1) for interior vehicle trim or upholstery, said part (1) comprising a visible composite covering layer (2) and a rear support layer (3), assembled together. Said composite covering layer (2) comprises a surface or appearance layer (4), in particular of the skin or textile type, an elastically compressible comfort layer (5) and, optionally, a functional or technical purpose layer (6). The support layer (3) is assembled, added or overmolded with or onto the covering layer (2) at the face of the latter opposite the surface or appearance layer (4), and the surface layer (4) comprises portions of seam lines (7) and / or local, in particular point, topstitching (7').

[0070] This part (1) is characterized in that the comfort layer (5) comprises at least two constituent components, namely, at least one first sub-layer (8) and at least one second sub-layer (9), this second sub-layer (9) being thicker and composed of a material more elastically resistant to compression than the first sub-layer (8), and in that said portions of sewing lines (7) and / or stitching (7') pass through at least the surface layer (4) and the comfort layer (5), and possibly also the functional layer (6) and / or the support layer (3), and that they produce localized compressions of said at least two constituent components (8 and 9), these compressions resulting in corresponding recesses (10) at the external face of the covering layer (2),said part (1) being obtained by means of the manufacturing process described above and having at least some of the characteristics mentioned above.

[0071] Of course, the invention is not limited to the embodiments described and shown in the attached drawings. Modifications remain possible, in particular from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

Claims

1. Method for manufacturing a part (1) of vehicle interior trim or upholstery, said part (1) comprising a visible composite covering layer (2) and a rear support layer (3), assembled together, said method consisting of providing a composite covering layer (2) comprising a flexible surface or appearance layer (4), in particular of the skin or textile type, an elastically compressible comfort layer (5) and, optionally, a functional or technical purpose layer (6), and assembling the support layer (3) with the covering layer (2), at the face of the latter opposite the surface or appearance layer (4), either by sheathing or adhesive or material bonding, or by overmolding the support layer (3) onto the covering layer (2), said method also consisting of producing at least in the surface layer (4) portions of seam lines (7) and / or local topstitching (7'),in particular punctual, method characterized in that it consists in providing a comfort layer (5) comprising at least two constituent components, namely, at least one first sub-layer (8) and at least one second sub-layer (9), this second sub-layer (9) being thicker and composed of a material more elastically resistant to compression, that is to say firmer, than the first sub-layer (8), and in that it consists in producing said portions of sewing lines (7) and / or topstitching (7') in such a way that they pass through at least the surface layer (4) and the comfort layer (5), and possibly the functional layer (6), or even where appropriate the support layer (3), and that they cause localized compressions of said at least two constituent components (8 and 9),these compressions resulting in corresponding indentations (10) at the level of the external face of the coating layer (2) and in local deformations of the surface or flexible appearance layer (4) resulting in a configuration of hollows and bumps.,

2. Method according to claim 1, characterized in that it consists of providing a first sub-layer (8) made of a cellular or foamed type material and a second sub-layer (9) made of a material composed of a multitude of elongated flexible elements (9') mutually juxtaposed and oriented in a direction substantially per- pendicular to the median plane of said sub-layer (9) in the absence of stress, so as to form a compressible layer, with a compressive strength determined according to the aforementioned direction.

3. Method according to claim 2, characterized in that the elongated flexible elements (9') are at least partly, preferably entirely, formed in one piece and from the material constituting the support layer (3).

4. Method according to any one of claims 1 to 3, characterized in that it consists in providing a functional layer (6) also crossed by said portions of seam lines (7) and / or topstitching (7'), and advantageously made of a non-woven fabric, for example PET or PP, this layer (6) serving as an assembly interface between the composite coating layer (2) and the support layer (3), and also as a rear, tensile-resistant bonding layer for said portions of seam lines (7) and / or topstitching (7').

5. Method according to any one of claims 1 to 4, characterized in that it consists of first assembling the different layers (4, 5, 6) forming the composite covering layer (2), then producing the portions of seam lines (7) and / or the topstitching (7') according to a predetermined implantation pattern and finally assembling the support layer (3) with said composite covering layer (2), or forming it on the latter, at the level of the functional or technically purposed layer (6) when it is present.

6. Method according to any one of claims 1 to 4, characterized in that it consists of first assembling the layers (4, 5, 6) to form the composite covering layer (2), then assembling the latter with the support layer (3), and then producing the portions of seam lines (7) and / or the topstitching (7') according to a predetermined implantation pattern, the latter (7, 7') also passing through said support layer (3).

7. Method according to any one of claims 1 to 4, characterized in that it consists of superimposing the different layers (4, 5, 6) forming the composite covering layer (2), and assembling these layers together and simultaneously with the support layer (3) when producing the portions of seam lines (7) and / or the topstitching (7') following a predetermined implantation pattern and crossing these different layers, a pre-assembly by stapling or nailing being able to be carried out if necessary.

8. Method according to any one of claims 5, 6 or 7, characterized in that it consists of securing, by gluing or sheathing for example, the different layers (4, 5, 6) forming the composite covering layer (2), where appropriate pre-assembled in a pre-formed composite covering layer (2), with the support layer (3), this in a mold (11) having a cavity (11') of a shape adapted to that of the part (1), and using a means (12) for applying said layers against said support layer (3), providing a pressure distributed surface-wise in a substantially uniform manner, positive or negative, for example by vacuum suction or by positioning and inflating an inflatable sheathing pocket or membrane.

9. Method according to any one of claims 1 to 8, characterized in that it consists of carrying out an operation of preforming or predeforming the composite coating layer (2) to generate a recess (10) at the locations of the portions of seam lines (7) and / or the stitches (7'), before their production, for example by the action of a tool (16), possibly hot, or by placing a retention element (16'), such as nailing or stapling, or by combined implementation of these two operations.

10. Method according to any one of claims 1 to 9, characterized in that it consists of subjecting the composite coating layer (2), before or after its assembly with the support layer (3), to a hot embossing operation so as to create a pattern printed in the thickness of said coating layer (2), defining at least for some the locations of the portions of seam lines (7) and / or local topstitching (7') carried out in a subsequent operation.

11. Method according to any one of claims 1 to 9, characterized in that it consists of subjecting the composite coating layer (2), before or after its assembly with the support layer (3), or at least the surface or appearance layer (4), to a printing operation aimed at creating a relief pattern imitating sewing lines or topstitching, at least some of these reliefs being completed, during a subsequent operation, by the production of portions of sewing lines (7) and / or real local topstitching (7').

12. A method according to any one of claims 1 to 11, characterized in that it consists in providing a covering layer (2) with a comfort layer (5) having a reduced thickness along at least one of the two sides of the coating layer (2). at least one of the edges (2') of said covering layer (2) intended to form an edge (1') of the part (1), this reduced thickness being obtained by total or partial removal of the second sub-layer (9), or removal of at least part of the thickness of the latter, or even where appropriate of the first sub-layer (8), the resulting strip of reduced thickness (5') of the comfort layer (5) being folded over or folded over the corresponding edge (3') of said support layer (3).

13. Method according to any one of claims 1 to 12, characterized in that it consists in providing a support layer (3) with at least one edge (3') having a peripheral rim (3”) in the form of a wing or a rib in one piece and with a rounded edge (13) and / or a body of curved shape in section and in folding or folding back a corresponding lateral edge strip (2') of said covering layer (2) around said rim (3”), preferably an edge strip (2') thinned in thickness over a width determined by partial or total removal or suppression of the second sub-layer (9), where appropriate of the first sub-layer (8), to form an edge (1') of the part (1).

14. Method according to any one of claims 1 to 13, characterized in that it consists in providing a support layer (3) provided with positioning means and / or indexing marks and in using these means and / or marks during the operation of assembling the covering layer (2) with this support layer (3).

15. Method according to claim 14, characterized in that it consists in providing a peripheral rim (3”) in the form of an outwardly curved and elastically deformable peripheral wing, with an end edge (13) in the form of a common terminal thickening, a second wing (14) intended for fixing the folded edge (2') of the covering layer (2) being optionally formed opposite the rim (3”).

16. Method according to any one of claims 1 to 15, characterized in that it consists of manufacturing several parts (1) of different shapes and intended to dress or cover distinct locations in the interior of a vehicle, these parts (1) being configured, in terms of distribution of the recesses (10) and of the portions of sewing lines (7) and / or of the local topstitching (7'), to provide a set of parts (1) producing by mutual juxtaposition, in the assembled state, a covering interior with a substantially uniform pattern.

17. Method according to any one of claims 1 to 16, characterized in that it consists of applying, over the surface or appearance layer (4), an additional protective and / or decorative layer (15), of an opaque, transparent or translucent nature, for example by applying it by thermo-sheathing.

18. Part (1) for interior vehicle trim or upholstery, said part (1) comprising a visible composite covering layer (2) and a rear support layer (3), assembled together, said composite covering layer (2) comprising a surface or appearance layer (4), in particular of the skin or textile type, an elastically compressible comfort layer (5) and, optionally, a functional or technical purpose layer (6), the support layer (3) being assembled, attached or overmolded with or onto the covering layer (2) at the level of the face of the latter opposite the surface or appearance layer (4), and the surface layer (4) comprising portions of seam lines (7) and / or local, in particular point, stitching (7'), part (1) characterized in that the comfort layer (5) comprises at least two constituent components, namely, at least one first sub-layer (8) and at least one second undercoat (9),this second underlayer (9) being thicker and composed of a material more elastically resistant to compression, i.e. firmer, than the first underlayer (8), and in that said portions of sewing lines (7) and / or topstitching (7') pass through at least the surface layer (4) and the comfort layer (5), and possibly also the functional layer (6) and / or the support layer (3), and that they carry out localized compressions of said at least two constituent components (8 and 9), these compressions resulting in corresponding recesses (10) at the level of the external face of the covering layer (2), said part being obtained by means of the manufacturing method according to any one of claims 1 to 17.,

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