FR3087700A1 - PROCESS FOR PRODUCING A SKIN - Google Patents

Abstract

Process for manufacturing a skin (1), comprising the following steps: production of a lower layer (2) by an additive technique, preferably by 3D printing, and molding of an upper layer (3), directly on the layer lower (2).

Description

Method of manufacturing a skin The present invention relates to the dressing and production of a skin, intended to form a surface coating so as to produce a decorative and neat finish.

Such skins are typically used in the home, or even in the automobile, both indoors and outdoors, to produce a protective and aesthetic finish.

In the field of decorative covering, it is known practice to mix materials, most often plastic, in order to obtain decorative effects.

However, the technologies used for these materials all employ molds and the need for demoulding entails so-called undercuts constraints which greatly limit the decorative possibilities.

The object of the invention is to release these constraints in order to broaden the possibilities offered to skin designers.

For this the invention proposes a method of manufacturing a skin comprising the following steps: production of a lower layer by an additive technique, preferably by 3D printing, and molding of an upper layer, directly on the lower layer.

According to another characteristic of the invention, the upper layer is made of a translucent material, preferably transparent.

According to another characteristic of the invention, the molding step is carried out by low pressure technology.

According to another characteristic of the invention, the upper layer has an upper surface substantially parallel to the plane of extension of the skin, preferably smooth.

According to another characteristic of the invention, the lower layer comprises at least one protuberance comprising at least one undercut.

According to another characteristic of the invention, the lower layer comprises at least one protuberance comprising at least one passage along at least one axis substantially parallel to the extension plane of the skin.

According to another characteristic of the invention, the lower layer comprises at least one protuberance having at least one negligible cross section in front of the longitudinal extension of the protuberance.

According to another characteristic of the invention, the method further comprises a step of adding a substrate layer under the lower layer.

According to another characteristic of the invention, the substrate layer comprises stiffeners and / or fixing means.

The invention also relates to a skin obtained by such a process.

Other characteristics, details and advantages of the invention will emerge more clearly from the detailed description given below by way of indication in relation to the drawings in which: FIG. 1 is a front view of an embodiment possible of a lower layer, - figure 2 is a side view of the lower layer of figure 1, - figure 3 is a front view of the lower layer of figure 1 covered with an upper layer, 10 - Figure 4 is a front view of the skin of Figure 3 associated with a substrate, - Figure 5 is a front view of another possible embodiment of a lower layer.

The object of the invention is to make it possible to produce a skin while freeing itself from the constraints conventionally associated with the use of plastics in an industrial manner.

These constraints include what are called draft stresses which force the molded parts to present angles, called draft angles, which are strictly positive, relative to a direction of release from the mold.

These constraints also include minimum thickness constraints so that demolding does not destroy too fragile parts.

In order to overcome these constraints, the method of manufacturing a skin 1 according to the invention produces a lower layer 2 without resorting to any technique requiring a mold.

Thus, since said lower layer 2 is not subject to release from the mold, it can be shaped while forgetting all the restrictive restrictions of the prior art, thus freeing the imagination of designers.

Figures 1, 5 show two examples among almost endless possibilities.

In these figures 1, 5 the skin 1 is presented in sectional front view.

The extension plane of the skin 1 is horizontal in the plane of Figures 1, 5.

In order not to resort to demoulding, said lower layer is produced by an additive technique.

Such an additive technique can be of any kind.

It is thus possible to produce the lower layer 2 by depositing, gluing or projecting, like a plaster, components, such as nodules or protuberances 21, on a support suitable for receiving them.

According to a preferred embodiment, the lower layer 2 can also be produced by 3D printing.

The lower layer 2, thus freed from the constraints of the prior art of plastic processing techniques, makes it possible to produce new, original patterns, offering original optical effects and thus carries most of the decorative function of the skin 1.

3 This release can lead to unsuspected shapes and in particular to protrusions 21 which, depending on their shape and / or their embodiment, may exhibit weaknesses and advantageously benefit from protection in order to increase their durability.

To this end, an upper layer 3 is produced, during a second step, preferably by molding, directly on the lower layer 2.

The lower layer 2 is advantageously used as (wall of a) mold for producing the upper layer 3.

The upper layer 3 thus has a mainly protective function.

FIG. 3 illustrates an upper layer 3 deposited on top of a lower layer 2.

The terms "lower" and "upper" characterize the layers relative to each other.

The bottom layer should be understood as the layer closest to a support, while the top layer is the topcoat, closer to the outside.

The top layer is closer to the visible side of the skin than the bottom layer.

These terms in no way presuppose a relative height of the 15 layers: in a skin to ceiling mounting, the lower layer would be above and the upper layer would be below.

Advantageously, so that the decorative effects produced by the shapes of the lower layer 2 are visible from the outside, the upper layer 3 is made of a translucent material, preferably transparent.

A transparent material 20 promotes the direct decorative expression of the lower layer 2.

A more or less translucent material completes the decorative effect by one or more “blur” effect (s) in which the upper layer 3 participates in the decorative effect.

Likewise, the lower layer 2 can also be made, at least partially, in a translucent material, preferably transparent.

This advantageously makes it possible to provide backlighting.

Such a material is advantageously PC, PMMA, TPU, polyester, vinyl ester, epoxy, polyurethane, silicone, resin or any other transparent / translucent thermoplastic material suitable for being molded.

The molding technology can be any technology capable of carrying out such an overmolding.

It can be cited: high pressure injection, low pressure resin overmolding, etc ...

However, and particularly if the lower layer 2 comprises patterns that are fragile or have little or no fixed, low pressure technology is preferred, in that it is less damaging to the lower layer 2.

Low pressure technology can be, for example, RTM (resin transfer molding) or RIM (reaction injection molding).

In the case of low pressure technology, the materials are preferably: polyester, vinyl ester, epoxy, polyurethane, silicone or resin.

Advantageously, the upper layer 3 has a thickness and a material capable of forming an effective protection of the lower layer against attacks of all kinds that may be encountered among, for example: impact, friction, wear, chemical, solar, etc.

The thickness of the upper layer 3 is advantageously at least equal to the thickness of the lower layer 2, so as to embed the lower layer 2 entirely in the protective layer that constitutes the upper layer 3.

The extra thickness is advantageously between 0 and a few millimeters.

According to one embodiment, the thickness of the upper layer 3 may still be less than the thickness of the lower layer 2, so as to allow the ends of protuberances 21 to protrude at least partially.

According to another characteristic, the upper surface 31 of the upper layer 15 3 is substantially parallel to the extension plane of the skin 1.

Its finish can be any.

Thus the upper surface 31 can participate in the decorative function in that it has a grain in order to impart a particular feel, a matt or glossy finish, etc.

According to a preferred embodiment, this upper surface is smooth.

While the embodiment of the lower layer 2 frees up its possibilities in terms of shapes, it also frees up its possibilities in terms of usable material.

According to one embodiment by deposition, gluing or projection, it is almost possible to use any type of material, including materials such as wood, metals, etc. and including by mixing them within the same skin 1.

In the case where 3D printing is chosen, this option limits the materials suitable for printing, but nevertheless offers a much wider choice than that offered by the plastics industry.

It is possible to include in the lower layer 2 metallic materials.

It is possible to include in the lower layer 2 transparent and / or translucent materials.

As illustrated in Figures 1, 2, 5 the lower layer 2 comprises at least one protuberance 21 having at least one undercut 22.

Since the lower layer 2 does not have to be demolded, it is possible to shape a protuberance 21 in the lower layer 2 with at least one undercut 22, i.e. a negative angle relative to the normal to the skin 1.

As illustrated in FIGS. 1, 2, the lower layer 2 comprises at least one protuberance 21 comprising at least one passage 23 along at least one axis substantially parallel to the extension plane of the skin 1.

Such a passage 23 can be made for decorative purposes, in that it allows the passage of light and thus allows the reflections to be varied.

Alternatively or complementarily, such a feed-through 23 can also be produced in order to facilitate the flow of materials during the molding of the upper layer 3 and thus facilitate filling and / or on the contrary 5 facilitate the exit of air and thus avoid the formation of bubbles.

As illustrated in Figures 1, 2, 5 the lower layer 2 comprises at least one protuberance 21 having at least one negligible cross section 24 in front of the longitudinal extension 25 of the protuberance 21.

The term “longitudinal section” is understood to mean a section cut by a plane aligned with the main direction of extension of the protuberance 21, ie substantially along normal to the plane of the layers 2, 3.

By cross section is meant a section cut by a plane secant to the main direction of extension of the protuberance 21, that is to say substantially parallel to the plane of the layers 2, 3.

By negligible is meant here a ratio, longitudinal section / transverse section, at least equal to 5.

This would not be possible with molding technology, in that the release would risk tearing off the protuberance 21, even in the absence of an undercut.

The height of a protuberance 21 relative to the base surface of the lower layer 2 is typically between 0 and a few millimeters, up to 10 mm, depending on the aesthetic effects sought.

It is possible to use a skin 1 comprising only a lower layer 2 and an upper layer 3, for example by fixing it by any means, for example by gluing, on a preferably rigid support, such as a dashboard or a bodywork. .

Additive technology and particularly 3D printing is an expensive technology.

Also, this naturally leads to limiting the thickness of the lower layer 2.

Likewise, in order to obtain good optical characteristics, it is desirable for the thickness of the upper layer 3 to remain low.

Also the assembly comprising a lower layer 2 and an upper layer 3 may suffer, for certain applications, from a lack of rigidity or a lack of fixing means.

Also, according to another characteristic, it is possible, as illustrated in FIG. 4, to add a substrate layer 4 under the lower layer 2.

Such a substrate layer 4 can be assembled under the lower layer 3 by any means.

By way of example, mention may be made of bonding, or even overmolding.

The term “under” is understood to mean an arrangement, relative to the lower layer 2, opposite to the upper layer 3.

Advantageously, the substrate layer 4 can receive stiffeners 41 and / or fixing means 42.

The stiffeners 41 are typically inclusions of rigid material 6 or even extra thicknesses, added or made of material, with the substrate layer 4.

The fixing means 42 are typically inclusions (screws, threaded bush, etc.) or even extra thicknesses, added or made of material, with the substrate layer 4, capable of allowing the fixing to be taken up again.

The invention further relates to a skin 1 obtained by any of the methods described herein.

This skin can be used in any decorative application anywhere, such as an interior or exterior of a motor vehicle, for example to produce a decorative insert in a dashboard,

Claims (10)

CLAIMS 1.- A method of manufacturing a skin (1), characterized in that it comprises the following steps: - production of a lower layer (2) by an additive technique, preferably by 3D printing, and - molding of an upper layer (3), directly on the lower layer (2). 2. A method according to claim 1, wherein the upper layer (3) is made of a translucent material, preferably transparent. 3. A method according to any one of claims 1 or 2, wherein the molding step is carried out by low pressure technology. 4. A method according to any one of claims 1 to 3, wherein the upper layer (3) has an upper surface (31) substantially parallel to the extension plane of the skin (1), preferably smooth. 5. A method according to any one of claims 1 to 4, wherein the lower layer (2) comprises at least one protuberance (21) comprising at least one undercut (22). 6. A method according to any one of claims 1 to 5, wherein the lower layer (2) comprises at least one protuberance (21) comprising at least one passage (23) along at least one axis substantially parallel to the extension plane. of the skin (1). 7. A method according to any one of claims 1 to 6, wherein the lower layer (2) comprises at least one protuberance (21) having at least one cross section (24) negligible in front of the longitudinal extension (25) of the protuberance (21). 8. A method according to any one of claims 1 to 7 further comprising a step of adding a substrate layer (4) under the lower layer (2). 8 9. A method according to claim 8, wherein the substrate layer (4) comprises stiffeners (41) and / or fixing means (42). 10. Skin (1) obtained by a method according to any one of the preceding claims.