EP3519659A1

EP3519659A1 - Internal connection part for a sandwich structure and corresponding assembly method

Info

Publication number: EP3519659A1
Application number: EP17781418.3A
Authority: EP
Inventors: Antoine SAINT-PIERRE
Original assignee: Novatech Europe
Current assignee: Novatech Europe
Priority date: 2016-09-27
Filing date: 2017-09-25
Publication date: 2019-08-07
Anticipated expiration: 2037-09-25
Also published as: FR3056624A1; EP3519659B1; FR3056624B1; WO2018060146A1

Abstract

The invention concerns a sandwich structure for a construction element comprising a quadrangular frame consisting of two uprights and two crosspieces, the frame being covered by two panels attached to either side of said frame such that the inner surface of each of said panels closes a cavity defined between the four inner faces of the uprights and crosspieces, characterised in that said frame cooperates with at least one connection part, a first face of which is in direct contact with the inner face of an upright and a second face of which is in direct contact with the inner face of a crosspiece adjacent to said upright.

Description

Inner connecting piece for sandwich structure and corresponding assembly method.

1. Domain

The field of the invention is that of the door openings, also called leaves, and more particularly the panel door openings. The invention also applies to partitions and panels for the construction of houses.

2. Prior Art

In known manner, the panel openings include a frame clamped between two panels, the latter defining with the frame a cavity in which an insulating material is injected. The frame is the result of the assembly of the uprights and cross members of the opening. Such an assembly can be implemented in different ways, depending in particular on the materials making up the amounts and crosspieces of the opening.

Thus, when the uprights and sleepers are made of wood, it is known to make a shoulder at the junction between the latter, and to secure them with screws or glue, as shown in FIG. la and lb.

According to another known embodiment, the frame can also be made with metal profiles, generally made of aluminum, or with composite materials. In this context, the assembly of the profiles together is generally achieved by means of a screwed bracket, as shown in FIG. 2.

Finally, when the uprights and sleepers are made of a polymeric material, such as polyvinyl chloride (PVC), a welded connection is generally preferred, as shown in FIG. 3.

These various known embodiments have various disadvantages.

In the first place, it has been found that such assemblies have an unsatisfactory mechanical strength over time. Indeed, the mechanical stresses experienced by the chassis tend to focus at the fastening systems, causing premature wear of the junction areas and consequently the entire chassis. This phenomenon is particularly observed in assemblies by PVC welding, given the rigidity of this material. The pressure exerted from inside of the cavity by the insulating material also tends to widen the junction areas, causing at the same time leakage through the frame.

Thus, such assemblies do not make it possible to implement a satisfactory partitioning between the cavity of the opening on the one hand and the outside of the chassis on the other hand. Indeed, given the existing gap between the various parts of the assembly and the generally hollow nature of the profiles, particularly in the metal-to-metal or composite versus composite assemblies, the insulating foam initially contained in the cavity tends to escape the chassis, thereby causing an aesthetic inconvenience and a degradation of the thermal properties of the opening, the concentration of insulation within the cavity is no longer at its optimum threshold. In return, the humidity contained in the ambient air is caused to infiltrate within the cavity, further degrading the thermal properties of the opening. To overcome these disadvantages, it is known to affix a silicone seal at the junction areas. Such a solution, however, has the disadvantage of further complicating the assembly process, while presenting risks concerning durability over time.

In addition, the methods used to produce such assemblies require specific mounting steps and require the implementation of specialized equipment.

For example, it is known to proceed with the welding of thermoplastic polymers by means of a heating mirror, ultrasound, a laser or a high frequency current. This mounting technique requires not only the use of suitable welding equipment, but also generally a skilled operator, and may further impose constraints on the choice of material profiles.

In the case of the joining of the adjacent sections by means of a fastening bracket, this method again requires a specific step during assembly, with several interventions calling quality and accuracy of execution.

Other known assembly techniques have the disadvantage of being complex, time-consuming and / or damaging the structure of the assembled parts. There is therefore a need to overcome these various drawbacks related to manufacturing and assembly constraints, the risks of unsatisfactory sealing of the structure and the degradation over time of its mechanical and thermal performance and its aesthetic appearance.

3. Summary

The proposed technique does not have these disadvantages of the prior art. More particularly, in at least one embodiment, the proposed technique relates to a sandwich structure for a construction element comprising a quadrangular chassis consisting of two uprights and two crosspieces, the chassis being covered by two panels attached on either side. said chassis so that the inner surface of each of said panels closes a cavity defined between the four internal faces of the uprights and crosspieces, characterized in that said frame cooperates mechanically with at least one inner connecting piece of which a first face is in contact direct with the inner face of an amount and a second face is in direct contact with the inner face of a cross adjacent to said amount.

The term "cavity" as used in the following description refers to a rectangular parallelepiped shaped volume, also called "soul", each of whose faces is closed by one of the internal faces of the frame or panels. Advantageously, an insulating material may be injected into this cavity in order to improve the thermal properties of the sandwich structure. Obviously, openings may remain at the junctions between the various elements of the assembly, and are the cause of several disadvantages which the present invention overcomes.

In the remainder of the description, the terms "in direct contact" qualify the mechanical connection established between two distinct parts of an assembly. According to some embodiments, this direct contact can in particular be summarized to a support-plane connection, without any additional fastening device is implemented.

The invention is based on a novel and inventive concept of providing a non-complex connecting piece, at least partially comprised within the cavity, and which improves the tightness of the structure at the targeted junction, as well as its mechanical behavior over time.

Thus, in view of the positioning of this connecting piece inside the cavity, the mechanical stresses exerted on this connecting piece by the pressure-insulating material participate in maintaining the latter against the upright and the cross member of the frame which are adjacent to it. The mechanical forces to provide for maintaining the position of the connecting piece are reduced and the frame has a better durability. The connecting piece also makes it possible to increase the shoulder area between an upright and a cross member, and vice versa, while guaranteeing a better squareness of the latter, that is to say a better right angle setting of the uprights and crosspieces. adjacent. Such a connecting piece further facilitates the implementation of a shoulder between an upright and a cross member, wherein the straightness between the outer surfaces of these parts is satisfactory.

Advantageously, it is possible to vary the contact surfaces of the connecting piece with the frame, according to the identified needs for cohesion between these different parts.

Due to the improved cohesion between the connecting piece and the frame, such a connecting piece also gives a better seal to the structure at the targeted junction. The risks of escape of insulating material from the cavity, as well as moisture infiltration within the latter, are therefore reduced. Accordingly, a sandwich structure according to the invention has improved thermal properties, as well as better aesthetics.

According to a particular characteristic of the invention, the connecting piece is connected by at least one attachment to the inner face of said upright and / or to the inner face of said crossbar.

The term "fixation", equivalent to the terms "fixation system" and "intrinsic fixation" means a device responding to the application of one or more techniques for securing two or more parts of an assembly. Such a fastener may for example be in the form of a screw-nut connection, elastic casing, also called clips, nailing, welding or gluing.

Advantageously, the connecting piece is both attached to the inner face of the upright and to the inner face of the cross member, thereby increasing the capacity of attachment of the connecting piece to the frame.

According to a particular characteristic, said attachment is removable.

The implementation of a removable attachment facilitates disassembly of the connecting piece, for example for the purpose of replacement or recycling of the latter, independently of the rest of the structure. According to a particular embodiment, the attachment may be of mechanical and / or electromagnetic type.

According to a particular characteristic, said attachment comprises at least one rounded assembly pad.

Such rounded studs allow a predetermined angular displacement between two parts during assembly. Therefore, these rounded pads make it easier to implement an assembly in a direction not strictly rectilinear.

According to a particular characteristic, said connecting piece comprises an outer portion arranged in the extension of said upright and / or said crossbar.

In the following description, the arrangement of a first part "in the extension" of a second part designates the positioning in direct contact of these first and second parts, so that the circumferential face of the first part has the same geometry. than the circumferential face of the second piece, of which it is the prolongation. Such an arrangement allows in particular the extension, on the outer portion of the connecting piece, a connecting element formed on the circumferential surface of the frame, e.g. a groove adapted to cooperate with the fold J of a panel. It is thus possible to increase the fixing surface of the panels on the frame. Even if the alignment of the circumferential surfaces, ie their straightness, is preferable, it is not strictly necessary.

According to a particular embodiment, this outer portion of connecting piece can be arranged in the extension of both the upright and a cross adjacent. Each of the circumferential faces of this outer portion then extends the circumferential face of an amount or an adjacent cross.

According to a particular embodiment, the connecting piece is monobloc.

The term "monoblock" as used in the description describes a unit formed of a single piece and not a permanent or temporary assembly of mechanical parts. Such a one-piece part can be manufactured according to large-scale industrial economic processes and implemented at high speeds, while having a satisfactory resistance to mechanical stresses.

According to a particular embodiment, the connecting piece is embedded between said upright and said cross.

Such a mechanical connection makes it possible to secure the connecting piece to the upright and passes through the chassis without necessarily implementing a fastening system.

According to a particular embodiment, the connecting piece comprises an exhaust channel in fluid communication with the cavity on the one hand and the outside of the frame on the other hand.

The implementation of such an exhaust channel makes it possible to control, in particular by selecting a predetermined shape and / or channel diameter, the air exhaust flow rate of the insulating material out of the cavity, especially during the injection of the latter. According to a particular embodiment, such a "controlled partial sealing" allows the evacuation of the air during the filling of the cavity of insulating material, while limiting the exhaust of the latter once the air has been evacuated . The controlled escape of the insulating material through the channel also ensures a better seal of the opening after solidification. Finally, the arrangement of this exhaust channel at a corner of the frame makes it possible to guarantee a homogeneous filling of the cavity to the ends of the corners, which injection processes of the state of the art do not require. not allow for an optimized and systematic way. According to a particular embodiment, this exhaust channel is in the form of at least one streak or micro-channel formed on a contact surface between the connecting piece and the frame.

According to a particular embodiment, the sandwich structure comprises at least one cap arranged in the extension of said upright and / or of said cross-member.

Such a hood makes it possible to reinforce the tightness of the chassis while offering an aesthetic comfort, since it is inscribed in the continuity of an upright and / or a cross-member. When this cover is implemented in combination with an outer portion of connecting piece, these two elements can be secured to one another by means of a fastener.

According to a particular embodiment, said upright and / or said crossbar are constituted by a hollow profile.

The hollow sections have the advantage of being easy to manufacture, e.g. by extrusion, and to be light, while maintaining satisfactory mechanical properties. According to particular embodiments, these hollow profiles have one or more cavities closed or open towards the outside, and are composed of metallic, plastic, ceramic or composite materials.

According to a particular embodiment, said upright and / or said cross member have a groove cooperating with a flange J of one of said panels.

The implementation of one or more J-shaped folds allows to maintain an assembly in position by the set of "extrinsic" elements to the connecting pieces and assembly of the uprights and sleepers between them, ie by the play of the folds in J, grooves, L-shaped folds, and not by "intrinsic" means, such as gluing or fastening with screws.

According to a particular embodiment, the J-folds are implemented at the circumferential surface of the uprights, which has the advantage of minimizing the deformation of the panels (more important at the L-shaped folds) on the part receiving the lock, where the operation opening / closing is essential.

However, the grooving of the frame is not necessarily limited to the amounts. Thus, according to a particular embodiment, a frame comprises two and a first cross member provided with a J-fold groove, the second cross-member being maintained via an L-shaped fold. According to another embodiment, two cross-members comprise a groove, while at least one of the posts is maintained via an L-shaped fold.

The technique also relates to a door leaf comprising such a sandwich structure.

Of course, all the technical improvements that can be applied to the sandwich structure described above can also be applied mutatis mutandis to a door leaf implementing such a sandwich structure.

The technique also relates to a method of assembling a door leaf comprising:

• the affixing on a flat surface of a first panel comprising a first protruding edge J and a second protruding edge J,

Positioning on said first panel of a parallelogram-shaped frame and comprising two uprights and two crosspieces respectively arranged in opposition two by two, said uprights and / or said sleepers each comprising on their outer circumference a groove adapted to cooperate with said J-edges so that said first J-edge is encased in the groove of one of said posts or sleepers; at least one connecting piece, comprising a first face and a second face perpendicular to each other, being arranged near the junction between an amount and a cross member forming an obtuse angle, so that said first face is arranged in direct contact with the inner face of said upright or said tie while said second face is arranged opposite said adjacent upright or said adjacent crossbar,

• affixing to said frame a second panel comprising a first edge J and a second opposite edge J so that said first edge J is embedded in said groove,

The subjection of said frame to a rectangular shape by angular displacement of the adjacent posts and crosspieces, so that the latter J-edges of said first and second panels are encased in the groove of said opposite post or said opposite cross-member, and said second face of said connecting piece is brought into direct contact with said adjacent post or said adjacent cross-member.

A method according to the invention thus makes it possible to uncomplicatedly assemble a door leaf, without necessarily having recourse to an intrinsic means for fixing the various components of the assembly to one another. By the set of extrinsic elements to the connecting pieces and assembly of the uprights and sleepers between them, ie by the play of J-folds, grooves, and possibly L-shaped folds, the assembly is thus maintained in a fixed position and sustainable. Furthermore, such an assembly method requires no specialized tools and can therefore be implemented by any operator and anywhere.

4. Figures

Other features and advantages will appear on reading the following description of particular embodiments of the invention, given by way of simple illustrative and non-limiting examples, and the appended drawings, among which:

Figure la is a diagram illustrating the shoulder assembly of a post and a wooden cross, according to a method of the state of the art;

Figure lb is a diagram illustrating the shoulder assembly and screwing of a upright and a wooden cross, according to a method of the state of the art;

Figure 2 is a diagram illustrating the assembly by means of a screwed bracket of two metal profiles, according to a method of the prior art;

Figure 3 is a diagram illustrating the assembly by welding of a polyvinyl chloride frame, according to a method of the state of the art;

Figure 4 is a diagram illustrating the junction between an upright and an adjacent cross member of a frame, according to a first embodiment of the invention; Figure 5 is a diagram illustrating the junction between an upright and an adjacent cross member of a frame, according to a particular embodiment of the invention; Figure 6 is a diagram illustrating the junction between an upright and an adjacent cross member of a frame, according to a second embodiment of the invention; Figure 7 is a logic diagram illustrating the successive steps implemented by a method of assembling a door leaf, according to a particular embodiment of the invention;

Figures 8a and 8b illustrate diagrams of a door leaf during assembly, according to a particular embodiment of the invention, respectively in a temporary parallelepipedal shape and in a final rectangular shape;

Figures 9 and 10 illustrate sections of the uprights / ties with the panels.

The various elements illustrated by the figures are not necessarily represented on a real scale, the emphasis being more on the representation of the general operation of the technique.

5. Detailed Description of Particular Embodiments of the Invention

The general principle of the invention is based on the implementation, in a sandwich structure and more particularly of a panel opening, of a connecting piece taking at least part of the support on the respective internal faces of an amount and an adjacent cross, of which this connecting piece seals the junction.

5.1 Assembly of a connection piece to the frame according to particular embodiments of the invention

Fig. 4 illustrates the junction between an upright 1 and an adjacent cross member 2 of a frame 3, according to a first embodiment of the invention. The upright 1 comprises an inner face 1a, oriented towards the inside of the frame 3, an opposite circumferential face 1b and two cross sections 1a, one of which is illustrated in FIG. 4. Similarly, the crossmember comprises an inner face 2a, an opposite circumferential face 2b and two cross sections 2c, one of which is illustrated in FIG. 4. According to this first embodiment, the cross-section 2c of the cross-member is partially attached in abutment against the upper end (as shown in Fig. 4) of the inner face 1a of the upright 1.

A connecting piece 4 in the form of a rectangular parallelepiped is attached in the corner of the frame 3 formed at the junction between the upright 1 and the cross member 2. The first face 4a and the second face 4b of the connecting piece 4 are respectively fixed to the internal faces (1a, 1b) of the upright 1 and the cross member 2. According to particular embodiments, such fasteners are of a mechanical nature and are in the form of a screw-nut connection, an elastic casing, nailing, welding, gluing or clipping of the connecting piece 4 in a dedicated groove formed in the inner face of an adjacent profile. According to another embodiment, the attachment is of electromagnetic nature and is performed by means of magnets. Fixing can also be both magnetic and mechanical, the magnetic fastening aiding in the proper positioning of the connecting piece while the mechanical fastening makes it possible to ensure a good hold of this fastening both in intensity and in time.

According to alternative embodiments, the connecting piece may have a triangular prism shape or any other shape comprising at least two perpendicular bearing faces. The materials used in the composition of the connecting piece may also vary depending on the constraints imposed on the manufacturer and the type of attachment envisaged.

Given the positioning of this connecting piece 4 inside the cavity 5, the mechanical stresses exerted on this connecting piece 4 by the pressure-insulating material contribute to the maintenance of the latter against the upright 1 and passes through 2 of the chassis 3. The mechanical forces to provide for maintaining the position of the connecting piece 4 are reduced and the frame 3 has a better durability over time.

Advantageously, it is possible to vary the contact surfaces (4a, 4b) of the connecting piece 4 with the frame 3, according to the identified needs for cohesion between these different parts. Thus, the connecting piece 4 shown in FIG. 5 has larger contact surfaces (4a, 4b), so as to facilitate the attachment of the connecting piece 4 to the frame 3 and therefore its insulating power.

Due to the improved cohesion between the connecting piece and the frame, such a connecting piece also gives a better seal to the structure at the targeted junction. The risks of escape of insulating material from the cavity, as well as moisture infiltration within the latter, are therefore reduced. According to embodiments of the invention, seals are also added at the attachment areas, so as to further strengthen the tightness of the assembly.

According to the first embodiment, a cap 6 shaped rectangular parallelepiped is also reported in the outer corner of the frame 3, in the extension of the amount 1 on the one hand and the cross 2 on the other. This cover 6 is thus fixed to the cross section of the upright 1 on the one hand and to the cross section 2c of the cross member 2 on the other hand. The circumferential surfaces of this cover 6 have the same geometry as the circumferential faces of the crossbar or the adjacent post.

Such a cover 6 makes it possible to reinforce the tightness of the frame 3 while offering an improved aesthetic, since it is inscribed in the extension of the upright 1 and the crossbar 2.

Fig. 6 illustrates the junction between an upright 1 and an adjacent cross member 2 of a frame 3, according to a second embodiment of the invention, wherein the upright 1 and the cross member 2 are not in direct contact.

A connecting piece 4 comprises an internal portion containing the technical characteristics of a connecting piece 4 according to the first embodiment described above, and an outer portion 4 'arranged in the extension of the upright 1 and transverse 2. This external portion 4 'thus consists of an intermediate portion 4'a, embedded between the upright 1 and the cross member 2, and a circumferential portion 4'b providing a function similar to that provided by a cover 6 according to the first embodiment of embodiment shown in FIG. 4. According to an alternative embodiment not illustrated, a cover 6 separate from the connecting piece 4 is substituted for this circumferential portion 4'b.

The implementation of a connecting piece 4 comprising such an outer portion 4 'has the advantage of not requiring the implementation of a fixing device with the frame 3. Indeed, the connecting piece 4 being embedded between the upright 1 and the crossbar 2, this mechanical connection is sufficient to ensure the joining of the connecting piece 4 to the frame 3.

In addition, the implementation of a connecting piece 4 monoblock comprising such an outer portion 4 'limits the play that may exist between the components of the assembly, due to different tolerance intervals. This assembly therefore has a better seal and a better mechanical behavior over time.

As illustrated in more detail in FIG. 9, the uprights 1 or the crosspieces 2 on opposite sides of the frame 3, are provided with a slot or groove 90a, 90b located on the sides 1b, 2b of the uprights 1 or crosspieces 2 concerned. defining the outer circumferential surface of the frame 3. The side panels 9a and 9b are provided on opposite edges with an essentially J-shaped flange 91a and 91b. This flange 91a, 91b comprises at its free end a wings 92a and 92b. extending substantially parallel to the side panel 9a, 9b concerned and cooperating with the slot or groove 90a, 90b concerned chassis 3 (the cooperation can be done by inserting the edge into the slot or groove or by applying the edge against the slot or groove) .

As illustrated in FIG. 10, the facings 9a, 9b may have, on at least one of their edges that do not have a flange, a substantially L-shaped flange 100a, 100b having a flange 101a, 101b extending substantially perpendicularly to the panel 9a, 9b concerned and folded against the outer peripheral edge 1b, 2b of the upright 1 or cross 2 concerned.

5.2 Method of assembling a door leaf according to a particular embodiment of the invention Fig. 7 is a logic diagram showing the successive steps of assembly of a sandwich structure 7 and more particularly of a door leaf 8 according to one embodiment of the invention.

A first panel 9a is first affixed (step SI) on a flat surface. This panel 9a comprises two protruding edges 91a opposite one another. In the example illustrated, the edges J are formed sides of the first panel 9a intended to cooperate with the uprights 1,.

In a second step, a chassis 3 in the form of a parallelogram and comprising two uprights (1; 1 ') and two crosspieces (2; 2') respectively arranged in opposition two by two, as shown in FIG. 8a, is positioned (step S2) on the first panel 9a. The uprights (1; 1 ') each comprise on their outer circumference a groove or slot 90a (not shown in FIG. 8a) adapted to cooperate with the edges J 91a of the first panel 9a. The frame 3 is positioned so that a first J-edge 91a is embedded in the groove or slot 90a of a first upright 1.

A connecting piece 4 is arranged near each of the corners of the frame 3 (inside corners), as shown in FIG. 8a. Thus, a first face 4a of each connecting piece 4 is fixed to the inner face 1a of an upright 1 while a second face 4b is arranged vis-à-vis the adjacent crossbar 2.

A second panel 9b comprising two opposite edges 91b is subsequently affixed (step S3) on the frame 3 so that one of its edges 91b is embedded in the groove or slot 90b of the first upright 1.

Finally, the frame 3 is secured (step S4) to a rectangular shape by angular displacement of the uprights 1 and 2 adjacent sleepers, so that the edges J 91a, 91b not embedded of the first panel 9a and the second panel 9b are embedded in the groove or slot 90a, 90b of the second upright 1 ', and the second face 4b of each connecting piece 4 is put in direct contact with the adjacent crossbeam 2. To do this, a push (arrows P) is exerted on one side of the frame 3 on one of the cross members 2, the frame 3 then passing from a parallelepiped shape to a rectangular shape by bringing the edges J not already embedded in a slot or groove to be housed there (see Figure 8b).

An assembly method according to the invention thus makes it possible to uncomplicatedly assemble a door leaf, without necessarily having recourse to specialized tools or to an intrinsic means of fixing the different components of the assembly to one another.

According to a particular embodiment, the assembly method comprises an additional step of forming L-folds 100a, 100b between the remaining edges of the panels 9a, 9b and the crosspieces (2; 2 '). Such L-shaped folds are formed by folding the edges of the panels 9a, 9b protruding on the crosspieces (2; 2 '). The formation of these L-shaped folds thus makes it possible, in addition to the folds in J, to join the panels 9a, 9b to the frame 3.

In the embodiment which has just been described, the edges J are formed on the sides of the panels intended to come into contact with the uprights. In a variant, they could be provided sides of the panels intended to cooperate with the sleepers. In this case, the grooves or slots are formed not in the amounts but in the sleepers. The process steps described above are thus modified so as to allow the embedding of the edges J of the panels in the slots or grooves of the sleepers. In this case, the connecting pieces 4 are secured to the sleepers rather than to the uprights.

In another variant, an L-shaped fold is formed from the outset at one end of each panel, the effort to conform the rectangle frame then being oriented towards the L-shaped folds of the panels. In the example illustrated in Figure 8a, an L-shaped fold would thus be formed at the end of each panel located on the side of the cross 2 '. During the deformation of the frame, the crossbar 2 'would then be brought into abutment against the L-shaped edges. A second L-shaped edge could then be formed on the other side of each panel.

In the case where the edges J are formed on the side of the crosspieces, the L-shaped edges are formed on the side of the uprights.

Claims

A sandwich structure (7) for a building element comprising:

A quadrangular frame (3) consisting of two uprights (1;) and two crosspieces (2; 2 '),

Two panels (9) attached to each side of said frame (3) and coating the latter so that the inner surface of each of said panels closes a cavity (5) defined between the four internal faces (la; ) uprights (1;) and crosspieces (2; 2 '), said panels each comprising two opposed J-shaped protruding edges cooperating with grooves formed in said uprights or said sleepers, for securing said panels to said frame, characterized in that said frame (3) mechanically cooperates with at least one inner connecting piece (4) of which a first face (4a) is in direct contact with the inner face (1a) of an upright (1) and a second face (4b) is in direct contact with the inner face (2a) of a cross member (2) adjacent said amount (1).

2. sandwich structure (7) according to claim 1, characterized in that said connecting piece (4) is bonded by at least one attachment to the inner face (la) of said upright (1) and / or to the inner face ( 2a) of said crossbar (2).

3. sandwich structure (7) according to claim 2, characterized in that said fixing is removable.

4. sandwich structure (7) according to one of claims 2 and 3, characterized in that said fixing comprises at least one rounded assembly pad.

5. sandwich structure (7) according to any one of claims 1 to 4, characterized in that said connecting piece (4) comprises an outer portion (4 ') arranged in the extension of said upright (1) and / or said crossbar (2).

6. sandwich structure (7) according to any one of claims 1 to 5, characterized in that said connecting piece (4) is monobloc.

7. sandwich structure (7) according to any one of claims 1 to 6, characterized in that said connecting piece (4) is embedded between said upright (1) and said crossbar (2).

8. sandwich structure (7) according to any one of claims 1 to 7, characterized in that said connecting piece (4) comprises an exhaust channel in fluid communication with the cavity (5) on the one hand and the outer frame (3) on the other hand.

9. Sandwich structure (7) according to claim 8 wherein said exhaust channel is in the form of at least one streak or micro-channel formed on a contact surface between the connecting piece and the frame.

10. sandwich structure (7) according to claim 8 or 9 wherein said exhaust channel is arranged in a corner of said frame.

11. sandwich structure (7) according to any one of claims 1 to 10, characterized in that it comprises at least one cover (6) arranged in the extension of said upright (1) and / or said crossbar (2). .

12. sandwich structure (7) according to any one of claims 1 to 11, characterized in that said upright (1) and / or said crossbar (2) are constituted by a hollow section.

13. sandwich structure (7) according to any one of claims 1 to 12, characterized in that the remaining edges of said panels (9) have L-shaped folds ensuring, in addition to said edges J, the joining of said panels (9 ) to said chassis (3) ..

14. A door leaf (8) comprising a sandwich structure (7) according to any one of the preceding claims.

15. A method of assembling a door leaf (8) comprising:

Apposition (SI) on a flat surface of a first panel (9a) comprising a first protruding edge in J and a second protruding edge in J,

Positioning (S2) on said first panel (9a) of a frame (3) in the form of a parallelogram and comprising two uprights (1; 1 ') and two crosspieces (2; 2') respectively arranged in opposition two by two; said posts (1; 1 ') and / or said crosspieces (2; 2') each having on their outer circumference a groove adapted to cooperate with said J-edges so that said first J-edge is embedded in the groove d one of said uprights (1; 1 ') or said sleepers (2; 2'); at least one connecting piece (4), comprising a first face (4a) and a second face (4b) perpendicular to each other, being arranged near the junction between a post (1) and a cross member (2) forming an angle obtuse, so that said first face (4a) is arranged in direct contact with the inner face (1a) of said upright (1) or said crossbar (2) while said second face (4b) is arranged vis-à- screw of said adjacent upright (1) or of said adjacent crossbar (2),

Apposition (S3) to said frame (3) of a second panel comprising a first J-edge and a second opposite J-edge so that said first J-edge is encased in said groove,

The subjection (S4) of said frame (3) to a rectangular shape by angular displacement of the uprights (1; 1 ') and crosspieces (2; 2') adjacent, so that said second edges J of said first and second panels (9) are encased in the groove of said opposite post () or said opposite crossmember (2 '), and that said second face (4b) of said connecting piece (4) is brought into direct contact with said post (1) adjacent or said crossbar (2) adjacent.

16. A method of assembly according to claim 15 comprising an additional step of forming L-shaped folds to the remaining edges of the panels (9) allowing, in addition to said edges J, to secure said panels (9) to said frame (3).