Bodywork or chassis component for a motor vehicle, particularly a door for a motor vehicle

Abstract

A bodywork or chassis component for a vehicle includes a first sheet having a first connection flange and a second sheet having a second connection flange, the first and second sheets being joined in correspondence of the respective first and second connection flanges. The first connection flange is a flange folded back towards the first sheet so as to define a valley with the first sheet. The second connection flange is overlapped to said first connection flange for an overlap length and it is at least in part joined to said first connection flange by a welding at that joins a perimeter edge of the second connection flange to a side of the first connection flange external with respect to said valley. The first and second connection flanges are parallel to one another in correspondence of the overlap length. The invention further includes a method for manufacturing of the aforementioned component.

Claims

1. A bodywork or chassis component for a motor vehicle including a first sheet having a first connection flange and a second sheet having a second connection flange, said first sheet and said second sheet being joined in correspondence of the respective first connection flange and second connection flange, wherein: the first connection flange is a flange folded back towards the first sheet so as to define a valley with the first sheet, the second connection flange overlaps the first connection flange over an overlap length and is at least in part joined to said first connection flange by a welding that joins a perimeter edge of the second connection flange to a side of the first connection flange external with respect to said valley, and wherein the first connection flange and the second connection flange are parallel to one another in correspondence of the overlap length, wherein said first sheet has a first thickness, said second sheet has a second thickness, wherein in correspondence of said overlap length said first thickness and second thickness are linked to said overlap length by the following relationships:
L=[2.Math.(t2/t1)] mm if 1.5t2/t1<2.5
L=max[(t2/t1) mm; 3 mm] if t2/t12.5 wherein furthermore 0.7t22 and 0.5t11.5, with t1<t2.

2. The component according to claim 1, wherein the first connection flange and the second connection flange are in contact to one another over the overlap length.

3. The component according to claim 1, wherein the first connection flange is folded back to define said valley so that an amplitude of said valley is higher than that of a capillary gap.

4. The component according to claim 1, wherein the first connection flange defines with the first sheet an angle comprised between 2 and 90.

5. The component according to claim 1, wherein said second connection flange is made by folding of a perimeter portion of said second sheet by an angle comprised between 0 and 15.

6. The component according to claim 1, wherein said first sheet and said second sheet are aluminum sheets, and said welding is a proximity laser welding performed with filler material.

7. The component according to claim 1, wherein the first connection flange defines with the first sheet an angle comprised between 15 and 20.

8. A method for manufacturing a component for a motor vehicle including a first sheet having a first connection flange and a second sheet having a second connection flange, the method comprising the steps of: providing the first sheet with the first connection flange with said first connection flange being folded back towards said first sheet to form a valley, bringing said second connection flange into contact with said first connection flange so as to define an acute angle of incidence therebetween, said contact occurring on a side of the first connection flange external to said valley, displacing at least one of said first connection flange and said second connection flange so as to impart an overlap and a parallelism condition therebetween in correspondence of an overlap length, and providing a welding joining a perimeter edge of said second connection flange to an external side of the first connection flange, said first sheet and said second sheet being joined in correspondence of the respective first connection flange and second connection flange, wherein said first sheet has a first thickness, said second sheet has a second thickness, wherein in correspondence of said overlap length said first thickness and second thickness are linked to said overlap length by the following relationships:
L=[2.Math.(t2/t1)] mm if 1.5t2/t1<2.5
L=max[(t2/t1) mm; 3 mm] if t2/t12.5 wherein furthermore 0.7t22 and 0.5t11.5, with t1<t2.

9. The method according to claim 8, wherein said displacing at least one of said first connection flange and the second connection flange includes displacing said second connection flange.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The invention will now be described with reference to the attached figures, provided purely by way of non limiting example, wherein:

(2) FIG. 1 is a front view of a bodywork or chassis component according to the invention, particularly a door for a motor vehicle,

(3) FIG. 2 is a sectional view according to line II-II of FIG. 1,

(4) FIG. 3 is a sectional view along line of FIG. 1,

(5) FIG. 4 is a section according to line IV-IV of FIG. 1, with FIG. 4A illustrating a possible variant of the section in correspondence of said line, and

(6) FIG. 5 is a sectional view according to line V-V of FIG. 1, while FIG. 5A is a perspective view according to line V-A of FIG. 1 that illustrates the sheets of the component in correspondence of the same section.

DETAILED DESCRIPTION

(7) Reference D in FIG. 1 indicates as a whole a bodywork component for a motor vehicle according to a preferred embodiment of the invention. Particularly, the reference D designates as a whole a door for a motor vehicle made by joining a first sheet 1 and a second sheet 2, wherein the sheet 1 is a skin sheet while the sheet 2 is a frame sheet, with a structural function. Particularly, the sheet 2 provides a load bearing frame for the door D, comprising in particular a hinge area H, a panel area B, and a frame area F, wherein the sheet 1 is superimposed to the sheet 2 substantially in correspondence of the panel area.

(8) With reference to FIGS. 2 to 5, the first sheet 1 and the second sheet 2 include, respectively a first connection flange 3 and a second connection flange 4 which are joined by means of welding (W in the figures) right in correspondence of the respective connection flanges.

(9) The first connection flange 3 is a flange folded back towards the first sheet 1 so as to define an open valley 5. In other words, the first connection flange 3 is folded back towards the first sheet 1 itself so as to provide a valley 5 whose width is greater than that of a capillary gap (that is, a condition of near-contact). This allows referring to an inner surface 1IN and an outer surface 1OUT of the first sheet 1. The reference that determines the characterization of the surfaces as belonging to the one or the other category (outer/inner) depends on the final position of the surfaces with respect to the geometry of the component, particularly a surface will be defined as inner when it faces towards the spatial region comprised between the two sheets 1 and 2, and a surface will be defined as a outer when it faces the opposite direction.

(10) Numerically, the angle comprised between the walls of the valley 5, identified with 5, is comprised between 2 and 90, preferably between 15 and 20. This corresponds to a folding back anglethat is an angle comprised between the surface 1IN or 1OUT on the flange 3 and the same surface on the remainder of the sheet 1comprised between 178 and 90, preferably 165 and 160.

(11) As far as a sheet 2 is concerned, the second connection flange 4 is arranged parallel and overlapping the first connection flange 3 in correspondence of an overlap length indicating by the letter L. This means that the angle comprised between the connection flanges 3 and 4 is substantially equal to 0.

(12) The second connection flange 4 is joined to the connection flange 3 by means of a welding W which joins a perimeter edge E2 of the first sheet 2 arranged in correspondence of the connection flange 4 with an outer side of the connection flange 3 which is part of the surface 1OUT, that is, an outer side with respect to the valley 5. The welding W is preferably a laser welding. When the sheets 1 and 2 are aluminum sheets, a preferred embodiment envisages providing the welding W as a proximity laser welding with filler material.

(13) It should be noted that the valley 5 is intrinsically arranged astride of the spatial region wherein the two sheets face, so that in the area of the connection flanges, the characterization outer or inner referred to the surfaces of the sheets may also have as a reference the valley 5 itself. On the basis of the same criteria, an inner surface 2IN and an outer surface 2OUT may be defined for the sheet 2, wherein in correspondence of the overlap length L the surfaces 1OUT and 2IN face one another. Depending on the embodiments, in correspondence of the overlap length a contact may occur between the flanges 3 and 4 or a condition of parallelism with a gap substantially akin to that of a capillary gap.

(14) The parallelism condition of the flanges 3 and 4 over the overlap length L is achieved in several sections of the door D, for example:

(15) with reference to FIG. 2, in a door section facing a sill of the chassis,

(16) with reference to FIG. 3, a door section proximate to the hinge area H,

(17) with reference to FIG. 4, a door section at the bottom of the frame area and in a position corresponding to the front pillar on the chassis,

(18) with reference to FIG. 5, a longitudinal section substantially intermediate with respect to the panel area B.

(19) Preferably, with reference to FIGS. 2, 3, 4, 4A, the flange 4 is madesimilarly to the flange 3by way of localized folding of a peripheral portion of the second sheet 2. However, the folding does not cover the same excursion that characterizes the flange 3, in so far as the surface (2IN or 2OUT, identically) of the flange is inclined by an acute angle 2 generally comprised between 0 and 15 with respect to the same surface (2IN or 2OUT) of the remainder of the sheet 2.

(20) FIGS. 4 and 4A illustrate how the overlap length L may be varied depending on the requirements, for example the design structural load, the sheet thickness (reference t1 for the sheet 1, t2 for the sheet 2) and so on.

(21) Specifically, FIG. 4 shows a condition wherein the overlap length, therein indicated by reference L, is lower than the overlap length L of FIG. 4.

(22) In this regard, the inventors have observed that in order to ensure the best dimensional stability with respect to the loads imparted after welding, in correspondence of the overlap area between the sheets the three parameters L, t1 and t2 may be linked to each other by the following relationships:
L=[2.Math.(t2/t1)] mm if 1.5t2/t1<2.5
L=max[(t2/t1) mm; 3 mm] if t2/t12.5

(23) wherein typical thickness figures are considered that correspond to 0.7t22 and 0.5t11.5 with t1<t2.

(24) Furthermore, in order to guarantee a sufficient dimensional stability of the door D in every condition, the overlap length L is chosen preferably equal or greater than 3 mm.

(25) As far as the welding method of the sheets 1 and 2 is concerned, the latter envisages that the connection flanges 3 and 4 be not parallel to each other in correspondence of the overlap length L, but be arranged incident by a very small angle, typically 3 or 4, to be subsequently forced into the parallel condition during the formation of the welded joint.

(26) The flange 3 is, to this end, preferably folded back so as to identify an angle 5 slightly greater than the value according to design specifications (for example, if the value according to design specification is equal to 20, the angle imparted preliminarily to the welding is about 2-3 greater).

(27) Upon the formation of the welded joint a force is applied, preferably via the welding equipment, that causes the closure of the flange 4 on the flange 3 (with nullification of the angle of incidence therebetween which has been imparted during the step preliminary to the execution of the joint), and that furthermore brings the value of the angle 5 to that according to design specifications, nullifying the excess imparted preliminary to the formation of the welded joint.

(28) The clamping blocks of the welding equipment shall be to this end arranged in a position sufficiently close to the position of the welding bead so as to be in a condition to exert an action needed for imparting the final geometry to the welding joint.

(29) More in detail, for the manufacturing of the door D (or in general any bodywork or chassis component for a motor vehicle) a method is implemented which comprises the steps of:

(30) providing the first sheet with the connection flange 3,

(31) providing the second sheet with the second flange 4,

(32) bringing the second connection flange 4 into contact with the first connection flange 3 so as to define an acute angle of incidence therebetween, the contact occurring on a side of the first connection flange 3 external to the valley 5,

(33) displacing at least one of said first connection flange 3 and second connection flange 4, preferably the flange 4, so as to impart an overlap and parallelism condition therebetween in correspondence of the overlap length L, and

(34) providing the welding W joining the perimeter edge E2 to the outer side 1OUT of the first connection flange 3.

(35) The person skilled in the art will thus appreciate that the solution shown in the present description allows eliminating all the drawbacks of the known solutions, both those featuring a hemming joint and subsequent welding, and those without a hemming joint, but having a welded joint on connection flanges, thanks to the parallel arrangement of the connection flanges in correspondence of the overlap length.

(36) Compared to the solutions featuring a hemming joint, the invention allows eliminating the sealing facilities inside the manufacturing plant, and accordingly all the operations related to the sealing itself, with subsequent savings in terms of investments, production times and labour.

(37) It is furthermore possible to eliminate the structural adhesive stocks, the equipment for dispensing the adhesive and subsequent operation of induction curing of the adhesive itself, as well as all the activities related to the supply logistics.

(38) Furthermore, with respect to the solutions featuring a hemming joint, dimensional stability is anyway increased insofar as strongly hyperstatic configurations are avoided which are typical of the hemming joining process, with subsequent reduction of the risk of distorsion of the sheets after welding owing to the aforementioned hyperstaticity.

(39) Compared to the solutions without a hemming joint, but featuring the sole welding on connection flanges, dimensional stability is remarkably increased insofar as the parallelism and the contact or near-contact between the flanges 3 and 4 allows to best bear the stresses acting on the door after welding, because the possibility of formation of a hinge in correspondence of the welding itself is prevented, which instead constitutes the main drawback of the solution known from EP 1 952 933 B1.

(40) The solution according to the invention can be furthermore implemented in every point of the door D, and is perfectly compatible with the provision of moisture drainage points P as illustrated in FIGS. 5 and 5A. In correspondence of the drainage point P the welding bead W is absent and the connection flange of each sheet is also interrupted (or at best the flange of the sheet 2) so as to open a passageway that provides the drainage P.

(41) Furthermore, the solution according to the invention can be adapted to a plurality of bodywork or chassis components for a motor vehicle wherein the joining of two superimposed sheets is required, for example pillars, spars, structural reinforcement, domes for motor vehicle suspensions and so on.

(42) Last the solution according to the invention turns out to be particularly advantageous, specially for a door D, insofar as it easily allows to use metal sheets already being part of normal production items. This is particularly true in respect of the sheet 2, which may be obtained simply by folding the edge of a pre-existing sheets to form the flange 4. This owing to the fact that the parallelism and the contact or near-contact condition between the flanges 3 and 4 creates a small variation in the relative position of the sheets 1 and 2 in case the latter are joined by means of a hemming joint and subsequent welding.

(43) On the contrary, a solution such as that described in EP 1 952 933 B1 is susceptible of introducing an appreciable variation of the relative position of the sheets 3 and 4 insofar as the angle of incidence of the second sheet with respect to the folded back flange ? to the angle between the folded back flange and corresponding sheet, thereby making it impossible to use pre-existing metal sheets without massive modifications.

(44) Contrary to the solution according to the invention, the slide folding that preferably is provided in correspondence of the perimeter edge of the second sheet compensates for the effects on the relative position of the sheets 1 and 2 due to the angle 5.

(45) Of course, the constructional details and the embodiments may be widely vary with respect to what described and shown herein, without by this departing from the scope of the present invention, as defined by the appended claims.