METHOD OF ASSEMBLING TWO SHEET METAL COMPONENTS SUCH AS VEHICLE BODYWORK COMPONENTS

Abstract

The invention relates to a method of assembling two sheet metal elements (1, 1′), involving applying a bead of adhesive to a first element, assembling the second sheet metal element on the first and securing it by spot welds to hold the two sheet metal elements stationary before curing the adhesive. The invention consists in the fact that the bead of adhesive is applied discontinuously to the first sheet metal element (1) along an adhesive line and then, once the second sheet metal element (1′) has been pressed against the first, the two elements (1, 1′) are held fixed together by creating spot welds on sections of the discontinuous adhesive line that are devoid of adhesive.

Claims

1. A method of assembling two metal sheet elements comprising depositing a bead of adhesive on a first sheet-metal element, assembling of a second sheet-metal element on the first sheet-metal element, and positionally fixing two sheet metal elements relative to each other by forming spot welds until the adhesive is cured, wherein the bead of adhesive is deposited discontinuously along an adhesive line on the first sheet metal element to define adhesive-free sections along the discontinuous adhesive line, and then the second sheet metal element is pressed against the first sheet metal element, and the two sheet-metal elements are held immobile relative to each other by forming welding points at the adhesive-free sections of the discontinuous adhesive line.

2. The method of assembly according to claim 1, wherein the two sheet metal elements joined by the adhesive have a clearance of between 0.1 and 15 mm.

3. The method of assembly according to claim 1, wherein the clearance is between 0.2 and 0.3 mm.

4. The method of assembly according to claim 1, wherein the adhesive is of the epoxy, polyurethane type.

5. The method of assembly according to claim 1, wherein the spot welding is an electrical resistance welding.

6. The method of assembly according to claim 1, wherein the spot welding is laser welding.

7. The method of assembly according to claim 1, wherein the discontinuous adhesive line defines adhesive dashes which have a length of between 20 and 200 mm and wherein the adhesive-free sections have a length of between 15 and 50 mm.

8. The method of assembly according to claim 1, wherein the bead of adhesive, which is flattened by assembly between the two elements, preferably has a width of at least 10 mm.

9. A motor vehicle body wherein the body is at least partially formed from sheet metal elements joined by the method of assembling sheet metal elements according to claim 1.

10. A motor vehicle comprised at least in part of sheet metal elements assembled together according to the method of claim 1.

Description

DESCRIPTION OF THE FIGURES

[0024] The invention will now be described in greater detail, with reference to the drawing in which the individual FIGURE (FIG. 1) represents a plan view of the edge of an assembly produced according to the invention.

DESCRIPTION

[0025] In the manufacturing process of a motor vehicle, the assembly of the sheet-metal elements to form the rail body is effected by structural bonding, making it possible to increase the rigidity of the bodywork elements thus formed. In order to hold the fused-together elements immobile with respect to one another, and thus to fix the geometry of the bodywork elements until the moment of curing of the adhesive during the electrophoresis process, spot welding of these elements is carried out.

[0026] For this purpose, a bead of adhesive is deposited in a discontinuous manner on a sheet metal element 1, a second sheet metal element 1′ is assembled upon the first sheet metal element, and a resistance spot welding of the two sheet metal elements 1, 1′ is performed in the adhesive-free spaces or sections 2′ of the bead, or of the discontinuous adhesive seam. Thus, as can be seen in the FIGURE, the assembly line between the two sheet metal elements 1, 1′ is comprised of sections or dashes of adhesive 2 between which there are situated electric spot welds 3, such as, for example, a dash of adhesive, a spot weld, a dash of adhesive, a spot weld, etc.

[0027] The deposited adhesive bead sections 2 are calibrated according to the type of adhesive (epoxy, polyurethane) so that, during assembly, the bead of adhesive 2 forms a film between the two elements 1, 1′, whose thickness is between 0.2 and 0.3 mm, which corresponds to a gap between the sheet metal elements 1,1′ of between 0.2 and 0.3 mm. Preferably, the diameter of the deposited bead of adhesive corresponds to the clearance after assembly between the elements to which 2 mm is added.

[0028] If the clearance between the elements to be assembled is too large (greater than 1 mm), a loss of rigidity of the fusion thus produced can occur. In addition, if this clearance exceeds 2 mm, there is a risk of washing the adhesive (dislodged adhesive) during the washing step of the electrophoresis process.

[0029] Similarly, the depositing pitch of the bead of adhesive sections 2 is chosen so that the dispersion of the adhesive during assembly, and therefore spreading of the adhesive between the two elements, leaves a space 2′ free adhesive in order to produce a spot weld 3 by electrical resistance. Thus, the position of the bead of adhesive sections 2 is synchronized with the position of the spot welds 3. It is thus ensured that the spot welds 3 will not be made on the bead of adhesive.

[0030] Thus, by way of example, lengths of the beads 2 of adhesive can be deposited with a length of 120 mm and provide the adhesive-free sections 2′ with a length of 15 to 20 mm.

[0031] Preferably, dashes of adhesive are produced with a length of between 20 and 200 mm and the adhesive-free sections are produced with a length of between 15 and 50 mm. It is thus also possible to contemplate making the spot weld at a distance of 15 to 25 mm from a dash of adhesive, that is to say, an adhesive-free section of 30 to 50 mm between two successive dashes of adhesive.

[0032] The bead of adhesive once flattened by assembly between the two sheet metal elements preferably has a width of at least 10 mm.

[0033] The method of assembly of the invention therefore makes it possible to produce, during the stage of fastening, a rail body that maintains all its geometry. The rail body is then brought to the electrophoresis stage where the adhesive will be polymerized, fixing the assembly permanently.