SHEET METAL ASSEMBLY BY BONDING FOR A MOTOR VEHICLE

Abstract

SHEET METAL ASSEMBLY BY BONDING FOR A MOTOR VEHICLE The present invention relates to a sheet metal assembly (2), particularly for a motor vehicle, comprising: - a first sheet metal (6); - a second sheet metal (8) superimposed on the first sheet metal; - an intermediate sheet metal (7) disposed between the first and second sheets metal; - adhesive (4) between the first and intermediate sheets metal; notable in that the intermediate sheet metal includes perforations (7.1) through which the adhesive extends between said intermediate sheet metal and the second sheet metal, so as to ensure, with said adhesive, a bond between said intermediate sheet metal and each of said first and second sheets metal. (Figure to be published with the abbreviation: Figure 1)

Description

Title of the invention: ASSEMBLY OF SHEET METAL BY BONDING FOR A MOTOR VEHICLE Technical field

[0001] The present invention relates to the field of motor vehicles, more particularly the field of the structure of motor vehicles. Prior art

[0002] Current motor vehicles increasingly comprise stacks of several sheets, in particular at least three sheets, at the level of their structure, in order to guarantee rigid zones for shock absorption and / or stress distribution. In this respect, these stacks require bonding and / or assembly by welding in order to stiffen them to better distribute the stresses.

[0003] However, in order to ensure sufficient stiffness of the sheet metal assemblies, a significant quantity of glue is generally used, which makes conventional solutions uneconomical.

[0004] Published patent document US 6,221,507 A1 discloses an assembly of five structural panels by brazing comprising a central panel intended to melt under high temperature so as to fill perforations on the adjacent panels and thus ensure fixing of the five panels.

[0005] However, the solution presented by the document requires the structural panels to be subjected to relatively high temperatures (up to 620°C), which complicates the manufacturing process, the solution is therefore not suitable for an automotive application. Statement of the invention

[0006] The present invention aims to overcome at least one of the drawbacks of the aforementioned state of the art. More particularly, the invention aims to propose a solution making it possible to assemble at least three sheets economically and quickly, while improving the stiffness of the assembly.

[0007] To this end, the invention relates to an assembly of sheets, in particular for a motor vehicle, comprising: - a first sheet; - a second sheet superimposed on the first sheet; - an intermediate sheet arranged between the first sheet and the second sheet; - glue between the first sheet and the intermediate sheet; remarkable in that the intermediate sheet comprises punchings crossed by the glue extending between said intermediate sheet and the second sheet, so as to ensure with said glue a connection between said intermediate sheet and each of said first and second sheets.

[0008] According to one embodiment, the assembly further comprises at least one electrical resistance welding point providing a metallurgical connection between the intermediate sheet and each of the first and second sheets.

[0009] According to one embodiment, the glue corresponds to a single bead of glue extending longitudinally on the first sheet, said bead being aligned with the intermediate sheet punchings.

[0010] According to one embodiment, the glue comprises a total volume of at most 3 cm3.

[0011] According to one embodiment, the punches are longitudinally aligned.

[0012] According to one embodiment, the punchings extend over at least 80% of a total longitudinal extent of the sheets.

[0013] According to one embodiment, the intermediate sheet comprises between 5 and 40 punchings.

[0014] The invention also relates to a motor vehicle comprising an assembly of sheets, remarkable in that said assembly is according to the invention.

[0015] The invention also relates to a method of assembling sheets according to the invention, said method comprising the following steps: - application of a bead of glue on the first sheet; - bringing the intermediate sheet into contact with the first sheet, with alignment of the punchings and the bead of glue; - pressing the intermediate sheet against the first sheet until the glue is evacuated from the punchings; - positioning of the second sheet on the intermediate sheet so as to contact and spread the glue evacuated by the punching.

[0016] According to one embodiment, the method further comprises the following step: - welding the assembly of sheets by means of at least one electrical resistance welding point at one of two ends of the assembly of sheets along a longitudinal extent of said assembly, so as to ensure a metallurgical connection.

[0017] The measures of the invention are advantageous in that the intermediate sheet comprising punchings allows the use of a single bead of glue, because the punchings allow the glue to be spread from the first sheet to the second sheet, and thus optimize the quantity of glue used, while ensuring maximum stiffness and rigidity of the assembly, without generating additional costs.

[0018] In addition, the assembly of the invention ensures a significant weight saving thanks to the punching of the intermediate sheet. Brief description of the drawings

[0019] [Fig.l] schematically illustrates a side view of an assembly of sheets according to the invention, in which a single bead of glue is applied to a first sheet;

[0020] [Fig.2] represents a front view of an intermediate sheet disposed between the first sheet and a second sheet belonging to the assembly of [Fig.l];

[0021] [Fig.3] illustrates a side view of the assembly of sheets according to the invention, in which the glue is evacuated by punchings of the intermediate sheet;

[0022] [Fig.4] illustrates a side view of the assembly of sheets according to the invention, in which the second sheet is positioned on the intermediate sheet. Detailed description

[0023] [Fig.l] schematically illustrates a side view of an assembly of sheets 2 according to the invention, in which a single bead of glue 4 is applied to a first sheet 6.

[0024] Indeed, the assembly 2 comprises the first sheet 6, a second sheet 8 superimposed on said first sheet 6, as well as an intermediate sheet 7 arranged between the first sheet 6 and the second sheet 8.

[0025] The invention proposes a method for assembling sheets comprising a first step of applying a bead of glue 4 to the first sheet 6, followed by a step of bringing the intermediate sheet 7 into contact and pressing it on the first sheet 6, by means of a pressing force A.

[0026] Advantageously, the assembly 2 comprises a single bead of glue 4, thanks to the presence of a plurality of punchings 7.1 passing through an entire thickness of the intermediate sheet 7.

[0027] Indeed, bringing the intermediate sheet 7 into contact with the first sheet 6 comprises an alignment of the punchings 7.1 with the bead of glue 4. In this configuration, the glue 4 is able to pass through the entire thickness of the intermediate sheet 7 to reach the second sheet 8 and thus ensure adhesion of all three sheets 6, 7 and 8.

[0028] The punchings 7.1 are visible in [Fig. 2] which represents a front view of the intermediate sheet 7. Preferably, the latter comprises a substantially rectangular shape, but said sheet 7 is not limited to such a shape. Indeed, the assembly 2 of the invention can be arranged in various places of the motor vehicle, thus the different sheets can have shapes other than rectangular, for example, they can be substantially circular, or triangular, etc.

[0029] Preferably, the intermediate sheet 7 comprises between 2 and 100 punches 7.1, and more preferably between 5 and 40 punches 7.1. The latter correspond to cylindrical holes having a diameter of between 4 and 10 mm, and preferably being 8 mm. Each of the punches 7.1 and spaced from each other by approximately 12 mm (the term “approximately” here means ± 10 mm).

[0030] It can be seen in [Fig.2] that the punchings 7.1 are longitudinally aligned, however, the latter can be misaligned, or can form a profile which can be inclined at an angle of up to 20° relative to the longitudinal direction of the extent of the intermediate sheet 7.

[0031] Preferably, the punchings 7.1 extend over at least 50% of a total longitudinal extent of the intermediate sheet 7, and more preferably over at least 80% of said extent.

[0032] Advantageously, the intermediate sheet 7 is obtained by sheet metal stamping, and the punchings 7.1 are obtained during said stamping. To this end, the assembly 2 remains economical, at least because the production of the punchings 7.1 does not present any additional cost.

[0033] [Fig. 3] illustrates a side view of the assembly of sheets 2. This is another subsequent step of the sheet assembly method, in which the second sheet 8 is positioned for contact, by a force B, against the intermediate sheet 7 following the evacuation of the glue 4 from the punchings 7.1.

[0034] In the illustrated configuration, the glue 4 is evacuated from the punchings 7.1, which makes it possible to have a sufficient quantity of glue for the adhesion of the second sheet 8 with the intermediate sheet 7.

[0035] Preferably, the bead of glue 4 placed on the first sheet 6 is of the epoxy or polyurethane type, and comprises a total volume of between 1 and 5 cm3, and is more preferably less than or equal to 3 cm3, and is even more preferably equal to approximately 2 cm3.

[0036] [Fig.4] illustrates a side view of the assembly of sheets 2, at a final stage of the method of the invention, in which the second sheet 8 is positioned on the intermediate sheet 7.

[0037] It can be seen that the glue has been spread between each of the three sheets 6, 7 and 8, so as to ensure complete bonding of the assembly.

[0038] Advantageously, the punchings 7.1 act as an anchor of the first sheet 6 to the second sheet 8, further increasing the stiffening of the assembly 2. In fact, the glue crosslinks and adheres firmly to the sheets, thus forming a series of protuberances extending through the punchings 7.1 and firmly and securely fixing the sheets in position.

[0039] Bending tests were carried out on the assembly 2, in particular at three different points along the extent of the assembly 2, in order to measure the stiffness. The assembly 2 comprising a volume of 2 cm3 of glue 4, obtains a stiffness of 42 N / mm, which corresponds to an improvement of approximately 45% compared to conventional solutions requiring the use of two beads of glue 4, respec tively, to the first sheet and to an intermediate sheet without punchings. In addition, assembly 2 presents a considerable mass gain due to the presence of punchings 7.1.

[0040] Alternatively, the assembly may comprise more than three sheets, for example, five (or more) sheets. In this regard, the assembly will comprise an intermediate sheet devoid of holes, and first and second sheets having punchings for spreading the glue, respectively, towards a fourth and a fifth sheet.

[0041] Preferably, the assembly 2 is finalized by at least one spot weld 10 by electrical resistance ensuring a metallurgical connection between the intermediate sheet 7 and each of the first 6 and second sheets 8. More preferably, the assembly comprises a spot weld 10 on each of two ends 2.1 of the assembly 2. Advantageously, the spot welds 10 make it possible, together with the glue 4, to freeze in geometry and to guarantee a stiffening distributed in an optimized manner in the assembly 2, while allowing maximum stiffness of the assembly.

Claims

Claims

1. Assembly of sheets (2), in particular for a motor vehicle, comprising: - a first sheet (6); - a second sheet (8) superimposed on the first sheet (6); - an intermediate sheet (7) arranged between the first sheet (6) and the second sheet (8); - glue (4) between the first sheet (6) and the intermediate sheet (7); characterized in that the intermediate sheet (7) comprises punchings (7.1) crossed by the glue (4) extending between said intermediate sheet (7) and the second sheet (8), so as to ensure with said glue (4) a connection between said intermediate sheet (7) and each of said first (6) and second sheets (8).

2. Assembly of sheets (2) according to claim 1, further comprising at least one electrical resistance welding point (10) ensuring a metallurgical connection between the intermediate sheet (7) and each of the first (6) and second sheets (8).

3. Assembly of sheets (2) according to one of claims 1 and 2, in which the glue (4) corresponds to a single bead of glue (4) extending longitudinally on the first sheet (6), said bead (4) being aligned with the punchings (7.1) of the intermediate sheet (7).

4. Assembly of sheets (2) according to one of claims 1 to 3, in which the glue (4) comprises a total volume of at most 3 cm3.

5. Assembly of sheets (2) according to one of claims 1 to 4, in which the punchings (7.1) are longitudinally aligned.

6. Assembly of sheets (2) according to one of claims 1 to 5, in which the punchings (7.1) extend over at least 80% of a total longitudinal extent of the sheets.

7. Assembly of sheets (2) according to one of claims 1 to 6, in which the intermediate sheet (7) comprises between 5 and 40 punchings (7.1).

8. Motor vehicle (1) comprising an assembly of sheets (2), characterized in that said assembly (2) is according to one of claims 1 to 7.

9. Method for assembling sheets (2) according to one of claims 1 to 7, said method comprising the following steps: - application of a bead of glue (4) on the first sheet (6); - bringing the intermediate sheet (7) into contact with the first sheet (6), with an alignment of the punchings (7.1) and the bead of glue (4); - pressing the intermediate sheet (7) against the first sheet (6) until the glue (4) is evacuated from the punchings (7.1); - positioning of the second sheet (8) on the intermediate sheet (7) so as to contact and spread the glue (4) evacuated by the punchings (7.1).

10. The method of claim 9, further comprising the step of: - welding the assembly of sheets (2) by means of at least one welding point (10) by electrical resistance at one of two ends (2.1) of the assembly of sheets (2) along a longitudinal extent of said assembly (2), so as to ensure a metallurgical connection.

Images