METHOD FOR PRODUCING A HYBRID-STRUCTURE PART OF A MOTOR VEHICLE AND CORRESPONDING HYBRID-STRUCTURE PART

Abstract

The invention concerns a method for producing a hybrid-structure part of a motor vehicle, comprising shaping of a sheet of metallic material, the provision of a sheet of composite material, application of a layer of connecting material on a face of said metallic material sheet or on a face of said composite material sheet, the shaping of a hybrid element by shaping said composite material sheet to the shape of said metallic material sheet and joining the composite material sheet to the metallic material sheet by means of said connecting material layer, and the production of ngidification elements by overmoulding using a polymer material.

Claims

1. A method for producing a hybrid-structure part of a motor vehicle, characterized in that it comprises the following steps: (a) shaping of a sheet of metallic material, (b) provision of a sheet of composite material comprising at least one layer of fibers impregnated or embedded in a polymer matrix, said layer of fibers being selected from among a layer of unidirectional fibers and a layer of woven fibers, (c) application of a layer of bonding material on one face of said sheet of metallic material, before or after shaping, or on one face of said sheet of composite material before or after shaping, (d) formation of a hybrid element by shaping of said sheet of composite material to the shape of said sheet of metallic material and joining of the sheet of composite material to the sheet of metallic material by means of said layer of bonding material, so that the sheet of composite material partially covers a face of said sheet of metallic material, (e) production of rigidification elements by overmolding of at least a part of the shaped hybrid element using a polymer material to form a hybrid-structure part, so that the polymer material covers, at least partially, the parts of the face of the sheet of metallic material not covered by said sheet of composite material.

2. The production method according to claim 1, wherein the shaping step (d) of a hybrid element is a hot stamping step of said sheet of composite material on said sheet of metallic material under efficient temperature and pressure conditions to shape said sheet of composite material, the layer of bonding material being positioned between the sheet of composite material and the sheet of metallic material, said bonding material being able to join the sheet of composite material to the sheet of metallic material in the hot stamping conditions.

3. The production method according to claim 2, wherein the steps (d) and (e) are performed in the same tooling.

4. The production method according to claim 1, wherein the sheet of composite material provided in step (b) comprises at least one layer of unidirectional fibers and at least one layer of woven fibers.

5. The production method according to claim 1, wherein the sheet of composite material provided in step (b) comprises one or more layers of identical or different fibers, said fibers being selected from among glass fibers, carbon fibers, basalt fibers, metal fibers or aramid fibers.

6. The production method according to claim 1, wherein, during step (e), the shaped rigidification elements are stiffening ribs, optionally extending substantially perpendicularly to the sheet of composite material.

7. The production method according to claim 1, wherein randomly arranged fibers are added to the polymer used in step (e).

8. The production method according to claim 1, wherein the polymer material used in step (e) comprises: ground-up scraps derived from the sheet of composite material and from step (d) or step (b), optionally supplemented with a polymer, notably that present in the composite material of the sheet of composite material.

9. The production method according to claim 1, wherein the polymers present in the sheet of composite material and the polymer used in step (e) are identical or different and selected from among: aliphatic polyamides (PA), polyphthalamides (PPA), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polycarbonates (PC), polypropylene, the mixtures of one or more of the previously mentioned polymers, the polyester resins, vinylester resins, epoxy resins, polyurethane resins, mixtures of one or more of these resins.

10. A hybrid-structure part of a motor vehicle that can be obtained by implementing the method according to claim 1, comprising: a sheet of metallic material, a sheet of composite material, at least partly covering a face of said sheet of metallic material, the sheet of composite material comprising at least one layer of fibers impregnated or embedded in a polymer matrix, said layer of fibers being selected from among a layer of unidirectional fibers and a layer of woven fibers, a polymer material, notably molded, at least partially covering the face of said sheet of metallic material at least partially covered with the sheet of composite material, said polymer material optionally forming ribs, characterized in that the sheet of composite material partially covers the face of said sheet of metallic material and in that the polymer material at least partially covers the uncovered parts of this face.

11. A hybrid-structure part according to claim 10, characterized in that at least one edge of the sheet of metallic material comprises predetermined fastening areas that are covered neither by the sheet of composite material nor by the polymer material, said predetermined fastening areas being separated by areas covered with polymer material.

12. An assembly of a hybrid-structure part according to claim 11 and a structural, characterized in that the hybrid-structure part is attached to the structural part by the fastening areas.

13. The assembly according to claim 12, characterized in that said structural part has at least one edge on which an edge of the sheet of metallic material is fastened and in that said edge of the structural part has depressions, the areas of the edge between the depressions being in contact with the fastening areas of the sheet of metallic material and the depressions being in contact with the areas of the sheet of metallic material covered with polymer material.

Description

[0085] The invention will now be described in reference to the following non-limiting figures:

[0086] FIG. 1 is an exploded perspective view of an embodiment of a hybrid-structure part according to the invention,

[0087] FIG. 2 is a partial perspective view of a hybrid-structure part according to another embodiment, view of the concave side of the part,

[0088] FIG. 3a is a transversal cross-section of the part shown in FIG. 2, assembled to a structural part; FIG. 3b is a longitudinal cross-section of an edge of the part shown in FIG. 2, assembled to a structural part.

[0089] FIG. 1 represents a center structural pillar of a motor vehicle 10 comprising:

[0090] a shaped sheet of metallic material 12,

[0091] a shaped sheet of composite material 14,

[0092] a molded polymer material 16 at least partially covering the sheet of metallic material 12 covered with the sheet of composite material 14, the polymer material 16 optionally forming ribs 18.

[0093] The sheet of metallic material 12 is in the form of a hollow part, having a concave inner face 12a and a convex outer face 12b.

[0094] The sheet of composite material 14 covers the face 12a of the sheet of metallic material 12. This sheet of composite material 14 comprises several layers of fibers, impregnated or embedded in a polymer matrix.

[0095] It should be noted that the invention is not limited to a particular shape of the face 12a of the sheet of metallic material 12 on which the sheet of composite material 14 is applied, this face 12a being either a convex or other face.

[0096] The polymer material 16 here forms a network of ribs 18 extending advantageously inside the concavity of the sheets 12 and 14 and partly covering the edges of the two sheets 12, 14.

[0097] For example, a hybrid center pillar 10 comprising:

[0098] a steel sheet 10 with a thickness of 0.67 mm,

[0099] a 4.35 mm thick sheet of polyamide 66-based composite material containing 55 to 80% of unidirectional carbon fibers and woven glass fiber by weight, and

[0100] a 2 to 4.5 mm variable thickness of thermoplastic material 16 made of polyamide 66 containing 50% chopped glass fibers by weight, is 30% lighter in relation to an all-steel pillar, having the same impact behavior (checked through simulation, for example).

[0101] FIGS. 2 and 3a, 3b partially represent a hybrid-structure part 110 according to another embodiment. In this embodiment, the hybrid-structure part 110 also comprises a shaped sheet of metallic material 112, a shaped sheet of composite material 114 and a molded polymer material 116 partially covering the sheet of metallic material 112. As can be seen in FIGS. 2 and 3b, the polymer material 116 forms ribs 118.

[0102] As in the preceding embodiment, the sheet of metallic material 112 is in the form of a hollow part, having a concave inner face 112a and a convex outer face 112b.

[0103] In this embodiment, it should be noted that the sheet of metallic material 112 is not fully covered by the sheet of composite material 114, notably at its longitudinal edges 113a and 113b. These longitudinal edges 113a, 113b, have fastening areas 120 alternating with areas 122 covered in polymer material 116. The fastening areas 120 are covered neither by the sheet of composite material 114 nor by polymer material 116, allowing them to be secured to a structural part, notably to secure them by welding to a metal structural part.

[0104] Furthermore, it should be noted that the parts of the sheet of metallic material 112, which are not fastening areas 120 and that are not covered by the sheet of composite material 114, are covered with polymer material 116, as can be seen more particularly in FIG. 3a (left part of the figure). In other words, in this embodiment, in a transversal cross-section, each part of the sheet of metallic material 112 that is not attached to a structural part is covered either by the sheet of composite material 114, or by the polymer material 116. In another embodiment not shown, there may be parts of the sheet of metallic material 112 not attached to a structural part and not covered by any other material.

[0105] A metallic structural part 124 is partially shown in the cross-sections 3a and 3b. For better assembly with the hybrid-structure part 110, the edges of this part 124 have hollow areas or depressions 125 located opposite the areas 122 covered with polymer material 116 and designed to compensate the overthicknesses of the edge 113a due to the presence of these areas 122.