FR2785224A1 - Supple sandwich structure, e.g. for making seats, has foam inner layer and outer skins of thin and denser material - Google Patents

Abstract

The sandwich structure consists of a core (1) made from one or more layers of a foam of a thickness and density selected according to the degree of suppleness required, and two outer skins (2, 3) of a denser material giving the structure a required self-supporting capacity. The core and outer skins can be assembled by different methods, such as adhesion or thermal welding, or the structure can be made by injecting the foam between the two skins. The outer skins can be made from any flexible material, including thin plywood, leather, certain metals, such as steel, plastics or cardboard.

Description

The present invention relates to a sandwich structure of the type comprising a core covered with panels.

It applies in particular, but not exclusively to the production of furniture, such as seats, or partitions, or packaging or travel items.

At present, sandwich structures are used to produce panels that are both very light and have great rigidity. Such structures include a rigid core, for example made of foam, with a honeycomb or honeycomb structure, covered with rigid sheets of small thickness.

Sandwich structures are also known for their sound and thermal insulation properties. They also have the advantage of being able to be easily shaped to produce very varied and persistent forms.

Due to their rigidity, such structures are not suitable for producing seats which are comfortable.

The present invention aims to exploit the properties of ease of conformation of sandwich structures to produce comfortable seats. To this end, it offers a sandwich structure comprising a core covered with two facings.

According to the invention, this structure is characterized in that the core and the facings are made of flexible materials, the core being at least partially linked to the two facings to prevent any movement in translation of the core relative to the facings .

The invention thus makes it possible to obtain a structure which combines properties of flexibility and elasticity with the advantages of sandwich structures.

In fact, while being elastically deformable in bending and in torsion, this structure has a certain rigidity which makes it self-supporting and with lasting shape resistance. This rigidity is obtained by the fact that the structure has several layers linked together.

This structure can also deform elastically in compression. It is therefore perfectly suited to the production of comfortable and ergonomic seats, capable of deforming elastically to better distribute the forces.

 The core may consist of one or more layers of foam, for example made of neoprene, the thickness and density of which are chosen as a function of the desired flexibility of the sandwich structure.

The facings have a small thickness compared to the core and a higher density. Their respective thicknesses are chosen according to the desired properties of the structure, and in particular its self-supporting quality and its crushing capacity.

They can be made of any flexible material, such as fine plywood, leather, certain metals such as steel, plastics, or cardboard.

The different layers making up the structure according to the invention can be assembled by different techniques depending on the materials used, such as for example by bonding or heat welding. The structure can also be produced by injecting foam between the two facings.

The structure according to the invention can be shaped before it is assembled by separate molding of the different layers making up the structure. It can also be shaped by maintaining the various layers making up the structure in the desired configuration at the time of assembly, the fixing between them of the layers ensuring the maintenance of the structure in the printed form at the time of assembly.

An embodiment of the device according to the invention will be described below, by way of nonlimiting example, with reference to the accompanying drawings in which
Figure 1 shows in section a flexible sandwich structure
according to the invention;
Figure 2 shows in cross section a seat made from
of a sandwich structure according to the invention.

FIG. 1 represents a flexible sandwich structure according to the invention. It comprises a core 1 of a flexible material, elastically deformable and of low density, the faces of which are covered with facings 2,3 of small thickness and having greater hardness.

At least part of the surfaces of the core 1 in contact with the facings 2, 3 are linked to these, preferably all of these surfaces.

The connection between the different layers 1, 2,3 is obtained either by bonding, welding, heat welding, or sewing, or by injection of the material constituting the core 1 between the two facings 2,3. Of course, any other method making it possible to obtain a lasting bond between the layers can be used.

 The core has an average density preferably between 0.1 and 0.3. It can be made from flexible neoprene or polyurethane foam, or by springs or from new materials such as three-dimensional woven plastic threads. Its thickness can be constant or variable if it is desired that the structure has more flexible zones than others.

Of course, it can be produced in several layers of flexible materials and of low average density.

Furthermore, the two facings consist of denser sheets of flexible material such as thin plywood, plastic (for example polypropylene), leather, cardboard, steel, stainless steel, etc.

They can also be of different natures or comprise several layers of identical or different materials, and / or have variable thicknesses and densities. They can also be made up of several parts of different natures or include openwork areas, revealing the core of the structure.

In Figure 2, there is shown a piece of furniture such as an armchair which can be produced from a sandwich structure according to the invention. This chair has a tubular shape consisting of a relatively thick core 11 made of a sparse material, covered by an outer facing 12 which is denser and of small thickness. The outer facing 12 is for example made of leather or birch plywood a few millimeters thick, for example 1 to 2 mm, while the core which may be made of foam may be several centimeters thick.

This gives both the structure of the furniture, its trim and its surface appearance.

Depending on the mechanical properties of the materials constituting the core 11 and the outer facing 12, and the shape of the chair, an inner facing 13 can be added which increases the self-supporting quality of the entire structure.

The particular shape of the chair can be obtained by prior molding of the different layers, or by maintaining the shape of these at the time of their assembly by gluing or welding.

The tubular shape of the chair can also be obtained by molding.

Claims (8)

 1. Sandwich structure comprising a core (1) and two facings (2, 3), characterized in that the core (1) and the facings (2,3) are made of flexible materials, the core being linked to the at least partially to the two facings to prevent any translational movement of the core relative to the facings.  2. Sandwich structure according to claim 1, characterized in that the facings (2,3) have a small thickness relative to the core (1) and a higher average density.  3. Sandwich structure according to claim 1 or 2, characterized in that the core (1) is produced by injecting material between the two facings (2,3).  4. Sandwich structure according to claim 1 or 2, characterized in that the core (1) is linked to the facings (2,3) by gluing, welding, or sewing.  5. Sandwich structure according to one of the preceding claims, characterized in that it is shaped before it is assembled by separate molding of the core (1) and the facings (2,3).  6. Sandwich structure according to one of claims 1 to 4, characterized in that it is shaped at the time of its assembly by maintaining the core (1) and the facings (2,3) in the desired conformation during l 'assembly.  7. Sandwich structure according to one of the preceding claims, characterized in that the core (1) is linked to the facings (2,3) by all of its surfaces in contact with the facings.  8. Sandwich structure according to one of the preceding claims, characterized in that the core (1) and / or the facings are made of several layers of flexible materials.