FR3070314A1 - BI-SHELL VEHICLE DEVICE AND ITS ASSEMBLY METHOD - Google Patents

Abstract

This bi-shell vehicle device comprises a lower half-shell (1) and an upper half-shell (1 '), said lower (1) and upper (1') half-shells being made in sheet metal form, the half-shells (1, 1 ') have, on their respective periphery, at least one collar (6, 6'), the collar (6 or 6 ') of each half-shell (1 or 1') being respectively crimped on the other half-shell (1 or 1 '), and said collars (6, 6') are arranged in staggered rows. The invention also relates to a motor vehicle comprising this bi-shell device and the assembly method of said device.

Description

VEHICLE SHELL DEVICE AND ASSEMBLY METHOD

The subject of the invention is a dual-shell device for a motor vehicle and a method for assembling such a device. More particularly, but not exclusively, this dual-shell device consists of a ground connection device such as a suspension arm or a chassis part.

In the following, the present invention is illustrated with the production of a suspension arm, but it is understood that it can be applied mutatis mutandis to all vehicle devices essentially consisting of two sheet metal half-shells.

Thus, a suspension arm, otherwise called a “suspension triangle” because of its triangular shape, is a chassis member which connects a wheel support (front or rear) of a vehicle such as a rocket carrier, to the vehicle body or a cradle attached to the body.

More specifically, the suspension arm extends transversely from the chassis to which it is fixed by a pivot or ball joint, towards a wheel of the vehicle to which it is connected by means of the stub axle, which is capable of ensuring the rotation of wheel.

This pivot connection is ensured by a ball joint included in a housing at the level of the suspension arm, which is connected to the wheel support by means of a ball joint or arm.

A motor vehicle suspension arm comprises two half-shells, that is, a lower half-shell and an upper half-shell, conventionally produced using sheet steel.

The documents FR 3014753 and EP 2316618 are particularly known, which describe the elements mentioned above, namely a suspension arm and a ball joint support element, and the latter are also well known to those skilled in the art.

In the industry, several techniques for assembling a suspension arm exist, including assembly by welding known as MAG (gas

-2reacting with metal, in English "Metal Active Gas") and assembly by PSE (Electric Welding Points).

However, these techniques have many drawbacks, both from the design point of view and from the manufacturing point of view.

As for the design, it is sometimes very difficult to weld materials of different natures, for example an aluminum sheet sole with a sheet steel cross member.

In addition, it is difficult to weld together two sheets previously coated with a layer of zinc: upon contact of the molten filler wire with the coated sheet, the zinc which covers the sheet sublimes and gas bubbles can form inside the weld bead. These porosities are not always emerging and can mask a lack of connection between the assembled parts.

Furthermore, the dissipation of heat in the vicinity of the molten zone can transform the material or weaken its mechanical characteristics. It is therefore not uncommon to have to resort to a reinforcement operation by shot blasting of the welded area.

In addition, there is a break in stiffness at the weld beads.

Finally, the mass of the cords is not negligible.

The realization of PSE welding requires a specific arrangement around the perimeter of the suspension triangle (edge of 15 mm minimum) so that this arrangement weighs down the triangle and also hinders its implantation in the cradle connecting to the ground as well as for turning the wheels. (wheel / triangle interference and / or reduction in the turning radius).

As for manufacturing, many weld faults are often obtained, requiring rework and touch-up.

In addition, the fusion of zinc coatings creates smoke in the workshop and produces an aggressive light for the operator's eyes, requiring adequate protection and ventilation of the premises.

In addition, these welding operations consume energy (electricity, gas) as well as consumables (electrodes, etc.).

-3 Finally, the electrical welding points and the welding seams must be subjected to a destructive conformity check.

Document FR 3028194 is also known, which describes a method of assembling a ground connection piece (cradle) by clinching, but this technique can prove to be complex to implement. EP 1738842 and US Pat. No. 5,860,213 are also known, which describe an assembly of sheets using crimped collars, which does not necessarily provide good fixing between the two sheets.

Finally, document US 6857812 is known which describes an assembly of two sheets by hem crimping along their joining section, but this process is only possible when at least one of two sheets has a very high limit of elasticity.

The object of the present invention is to remedy the aforementioned drawbacks of the prior art.

To this end, the present invention provides a dual-shell vehicle device, comprising a lower half-shell and an upper half-shell, said lower and upper half-shells being produced in the form of metal sheet, characterized in that the half -shells have, on their respective periphery, at least one collar, the collar of each half-shell being respectively crimped on the other half-shell, and in that said collars are staggered.

The expression “staggered arrangement” means relative to the collars the fact that the latter extend alternately, along the joining edge of the half-shells, from the lower half-shell and from the upper half-shell in an opposite direction (towards the lower or upper part).

Thus, when the two half-shells are positioned facing each other to form the dual-shell device (awaiting the crimping of the collars, as shown in FIGS. 2a or 2b), the collet (s) of the lower half-shell extend, relative to the extension plane of said half-shell, substantially perpendicularly in the direction of the upper half-shell, while for the collar (s) of the upper half-shell, these extend in the direction of the lower half-shell.

The present invention has numerous advantages over the state of the art, a non-exhaustive list of which is presented below.

In the absence of any welding, the functional performance of the assembly is improved while avoiding causing thermal disturbances related to welding on the sheet.

This also makes it possible to assemble certain sheets even when welding is impossible for reasons of incompatibility of materials.

We also gain in assembly quality because the crimping process with staggered collars is much less dispersive than dispersion in weld quality.

Since the staggered collar crimping process does not generate thermal stresses, there is also a gain in geometric stability.

This also saves space in the factory, since the crimping operation can be carried out on a single machine, instead of having to have several welding robots.

The elimination of the contribution in terms of weld beads also leads to a gain in mass.

The economic gain can be counted both in material, due to the elimination of robots and gripping machines, as in consumables such as wires, electrodes, electrical energy, gas, etc.

The hygiene problem related to the fumes in the workshop is resolved.

Finally, among the other advantages, we can also mention non-destructive testing of the assembly, by simple measurement of the crimped thickness.

According to a possibility offered by the invention, at least one of the lower or upper half-shells has at least two collars.

Advantageously, the lower and upper half-shells each have a plurality of collars.

According to a particular characteristic, at least one of the half-shells consists of a sheet of steel.

According to another particular characteristic, the metal sheet of at least one of the two half-shells is coated with a coating layer, such as a layer of zinc.

According to a preferred embodiment of the invention, the two-leg device consists of a ground connection device, such as a suspension arm or a chassis part.

For the same purpose, the present invention also provides a motor vehicle, remarkable in that it comprises at least one dual-shell device as succinctly described above.

Still for the same purpose, the invention also provides a method for assembling a motor vehicle dual-shell device comprising a lower half-shell and an upper half-shell, said lower and upper half-shells being produced in the form of sheet metal characterized in that it comprises steps of:

- Making each of the half-shells by integrating at least one collar respectively;

- holding the lower and upper half-shells against each other in a press, the collars being staggered;

- crimping of said collars.

The advantages of the method and of the vehicle in accordance with the invention being similar to those of the dual-shell device listed above, they are not repeated here.

According to a particular characteristic of the process, the step of producing the half-shells consists of stamping.

According to one possibility offered by the invention, the metal sheet constituting at least one of the two upper and lower half-shells is previously coated with a coating layer, such as a layer of zinc.

Other aspects and advantages of the invention will appear on reading the following description of a particular embodiment, given by way of non-limiting example and with reference to the accompanying drawings, in which:

- Figure 1 is a schematic representation of a half-shell, lower or upper, of a conventional suspension arm;

- Figures 2a, 2b, 2c and 2d illustrate schematically and in section the successive steps of the method of assembling the half-shells according to the invention.

The dual-shell device comprises two half-shells 1, 1 'made of metal sheet, such as aluminum, steel or stainless steel (steel containing nickel and chromium) and these can optionally be coated with a layer. coating, for example intended to chemically protect the sheet, such as a layer of zinc, a layer of paint or polymer resin (plastic). The half-shells are conventionally formed from one or more sheets of sheet metal.

The two half-shells 1, 1 'can be of the same nature or possibly of a different nature, such as for example aluminum / steel, since the present invention makes it possible to produce such assemblies. One of the two half-shells 1 or 1 ′ may also have different mechanical properties from the other, while possibly using an identical material (for example steels of different grades), so that one of the half-shells 1 or 1 ′ may have, for example, a much greater elasticity than the other in order to impart asymmetrical mechanical properties to the two-shell device.

As explained above, the invention is illustrated here in an application to a suspension arm, but this application is in no way limiting and does not exclude other applications provided that the device consists essentially of two half-shells in metal sheet intended to be assembled.

Thus, Figure 1 shows a half-shell, lower 1 or upper 1 ’, of a suspension arm. A suspension arm, as well as the two half-shells 1, 1 'which compose it, can be presented in various configurations but conventionally has the general shape of a triangle, like each of the two half-shells 1, 1 '.

-7 This half-shell 1, 1 ′ comprises three arms 2, 3, 4 extending substantially along, or in, an extension plane P. Two ends of the arms 2, 3 have an orifice of predetermined size to allow the mounting and connection to other elements of the chassis while the last arm end 4 includes a ball joint support element 5.

The half-shell 1 or 1 ’shown in FIG. 1 does not have one or more collars 6, 6’ according to the invention. As is apparent in particular in Figure 2a which has half-shells 1, 1 'in section, these collars 6, 6' according to the invention extend substantially perpendicularly to the plane of extension P of the upper half-shells 1 'or less 1. These collars 6, 6' are advantageously formed during the production of the half-shell by stamping, that is to say by mechanical deformation.

It should be noted here that the stamping of the metal sheets to form the upper 1 ′ or lower 1 half-shells 1, with their collars 6, 6 ’, is advantageously carried out cold, that is to say at room temperature. However, it is possible to carry out this hot stamping, depending on the nature and characteristics of the metal sheets used.

The shape of the collars 6, 6 ’can optionally be obtained independently by folding or lifting their edges. It will be noted that these shaping techniques only involve small deformations in the plane of the sheet and are compatible in particular with steels with very high yield strength having a low forming capacity.

It will also be noted that prior to the step of forming the half-shells 1, 1 ′ from a metal sheet, the latter may have been coated with one or more layers of coating or have undergone one or more surface treatments (sandblasting, physico-chemical treatments, etc.).

When the half-shells 1,1 'are placed facing one another, or facing each other, the collars 6 of the lower half-shell 1 extend in the direction of the half-shell while the 6 'collars of the

-8 upper half-shell 1 'extend towards the lower half-shell 1.

The collar (s) 6, 6 'of one of the half-shells 1 or 1' are positioned offset on the periphery of the half-shell 1 or 1 'relative to the collar (s) present on the 'other half-shell 1 or 1'.

The invention provides, in its broadest acceptance, the fact that each of the half-shells 1, 1 ’comprises only a single collar 6, 6’. In this embodiment, the collar 6, 6 'of each of the half-shells 1, 1' can advantageously have a width, possibly a thickness, sufficient to ensure the desired fixing of the half-shells 1, 1 'between them. The diameter, or radius of curvature, of the crimped collars 6, 6 ′ may also vary depending on the mechanical characteristics sought as well as the more or less complex shape of the two-shell device.

The staggered arrangement includes this embodiment in which each half-shell 1 or 1 ’comprises only a single collar 6, 6’. However, it is more generally provided that at least one of the half-shells 1 or 1 'has a plurality (at least two) of collars 6 or 6' and preferably the two half-shells 1,1 'have a plurality of collars 6, 6 '. In this embodiment, the staggered arrangement means that along the periphery (or junction edge of the half-shells 1.1 'forming the triangle) of the dual-shell device, the crimped collars 6, 6' coming from each of the half-shells 1, 1 ′ are arranged offset and alternately. More precisely, along this periphery, or edge of junction, a collar 6 from the lower half-shell 1 precedes a collar 6 'from the upper half-shell 1' and a collar 6 'from the half-shell upper 1 'follows a collar 6 from the lower half-shell 1.

The choice of the number of collars 6, 6 ', as well as their widths and / or their thicknesses, is directly linked to the rigidity of the desired fixing between the two half-shells 1,1' (elastic behavior or not), being considered that the nature of the sheet chosen for the half-shells 1, 1 ′ is also a determining criterion.

-9In an embodiment in which the metal sheet constituting the half-shells 1,1 'consists of steel, or even aluminum, while its thickness is reduced to take into account the requirements of weight reduction of the motor vehicle, each half-shell 1.1 ′ may advantageously include at least three collars 6, 6 ′.

Thus, each 1.1 ′ half-shell can have a large number of collars 6, 6 ′ depending on the mechanical characteristics sought for the bi-shell device.

As illustrated in particular in FIGS. 2a and 2b, once the half-shells 1,1 ′ each with one or more collars 6, 6, formed, advantageously by stamping, a lower half-shell 1 is placed opposite a half - upper shell T, the collars 6, 6 'then being staggered along the periphery of the dual-shell device. A pair of half-shells 1, T, thus positioned, is held in a press 7 comprising punches 8, suitably arranged on the lower and upper plates of the press 7 and intended for crimping the collars 6, 6 ’. The punches 8, intended to push the material of the collars 6, 6 'during the movement of the press 7, are advantageously removable and interchangeable. Of course, the shape of these punches 8 is suitable for carrying out the crimping of the collars 6, 6 ′ of the half-shells 1, T, the punches 8 can for example have a conical shape or at least one oblique or inclined surface / contour to gradually crimp the collars 6, 6 'when the internal walls of the press 7 are tightened.

Figures 2b and 2c show the movement of the press 7, before and after crimping the collars 6, 6 ', while Figure 2d shows, in cross section, half-shells 1.1' according to the invention assembled together to form a suspension arm.

Claims (11)

1. Bi-shell vehicle device, comprising a lower half-shell (1) and an upper half-shell (1 '), said lower (1) and upper (1') half-shells being made in the form of metal sheet , characterized in that the half-shells (1, 1 ') have, on their respective periphery, at least one collar (6, 6'), the collar (6 or 6 ') of each half-shell (1 or 1 ') being respectively crimped on the other half-shell (1 or 1'), and in that said collars (6, 6 ') are staggered. 2. Device according to claim 1, characterized in that at least one of the lower (1) or upper (1 ’) half-shells has at least two collars (6 or 6’). 3. Device according to claim 1 or 2, characterized in that the lower (1) and upper (1 ’) half-shells each have a plurality of collars (6, 6’). 4. Device according to one of the preceding claims, characterized in that at least one of the half-shells (1, 1 ’) consists of a sheet of steel. 5. Device according to any one of the preceding claims, characterized in that the metal sheet of at least one of the two half-shells (1 or 1 ') is coated with a coating layer, such as a layer of zinc. 6. Device according to any one of the preceding claims, characterized in that it consists of a ground connection device, such as a suspension arm or a chassis part. 7. Motor vehicle, characterized in that it comprises at least one dual-shell device according to any one of the preceding claims. 8. Method for assembling a motor vehicle dual-shell device comprising a lower half-shell (1) and an upper half-shell (1 '), said lower (1) and upper (1') half-shells being produced in the form of metal sheet, characterized in that it comprises steps of: - production of each of the half-shells (1, T) by integrating at least one collar (6, 6 ’) respectively; 5 - holding the lower (1) and upper (T) half-shells against one another in a press (7), the collars (6, 6 ’) being staggered; - crimping of said collars (6, 6 ’). 9. Method according to claim 8, characterized in that the step of producing the half-shells (1, T) consists of a stamping. 10. Method according to claim 8 or 9, characterized in that the metal sheet constituting at least one of the two lower half-shells (1) and upper (T) is previously coated with a layer of 15 coating, such as a layer of zinc.