Method for producing a semi-finished product or component comprising a metal carrier and a hardenable coating with fiber-reinforced plastic

Abstract

The invention relates to a method for producing a semi-finished product or component (2), in which a hardenable coating (6, 17) with fiber-reinforced plastic is applied to a metal carrier (3), particularly a metal sheet (4), and the coated metal carrier (3) is formed, particularly deep-drawn or bent, in a subsequent step to produce a semi-finished product or component (2). According to the invention, for an improved and cost-effective method, the metal carrier (3) is coated at most only in certain regions and is only subjected to the forming when the coating thereof (6, 17) has hardened to produce at least a block-resistant surface (12), the coated metal carrier (3) being formed such that the plastic changes in shape follow forming radii (21) and are produced substantially, preferably exclusively, in the coating-free regions (15) of the metal carrier.

Claims

1. Method for the production of a semi-finished product or component, the method comprising steps of: applying a hardenable coating with fiber-reinforced plastic to a metal support, the hardenable coating being applied to certain regions of the metal support and other regions of the metal support being left free as coating-free regions, hardening the hardenable coating on the metal support such that the hardenable coating forms a block-resistant surface, and forming the coated metal support with the block-resistant surface such that the metal support undergoes plastic deformation along forming radii, the forming radii being exclusively in the coating-free regions of the metal support.

2. Method according to claim 1, wherein carbon-fiber-reinforced plastic is applied to the metal support with a duroplastic matrix as the fiber-reinforced plastic.

3. Method according to claim 2, wherein pre-impregnated carbon fibers are applied.

4. Method according to claim 1, wherein fiber-reinforced plastic is applied to the metal support with a chemically cross-linked intermediate layer.

5. Method according to claim 1, wherein the fiber-reinforced plastic has long fibers.

6. Method according to claim 1, wherein a woven fabric or laid scrim of the fiber-reinforced plastic is applied to the metal support in cut-to-size form.

7. Method according to claim 6, wherein the woven fabric or the laid scrim is either applied to the metal support pre-impregnated with the plastic matrix, or impregnated with the plastic matrix after application to the metal support.

8. Method according to claim 1, further comprising a step of metallically and/or organically pre-coating the metal support before applying the hardenable coating.

9. Method according to claim 8, wherein an adhesion-promoting agent is used to metallically and/or organically pre-coat the metal support.

10. Method according to claim 1, wherein multiple plies of woven fabric or laid scrim are laid one on top of the other for a multidirectional layer structure of the fiber-reinforced plastic.

11. Method according to claim 1, wherein a parting layer is applied to the coating before forming.

12. Method according to claim 1, wherein the metal support is a sheet having a sheet thickness of 0.6 to 5 mm.

13. Method according to claim 1, wherein the hardenable coating has a thickness of 0.2 to 3 mm.

14. Method according to claim 1, wherein the hardenable coating is pre-gelled without pressure and is pressed onto the metal support in a further step, in order to apply it to the metal support.

15. Method according to claim 1, further comprising a step of: producing a supporting structural component from the formed coated metal support.

16. Method according to claim 15, wherein the supporting structural component is selected from the group consisting of a rocker panel of a motor vehicle and a side member of a motor vehicle.

17. Method according to claim 1, wherein the metal support is sheet metal.

18. Method according to claim 1, wherein the forming step comprises deep-drawing or bending of the coated metal support with the block-resistant surface.

19. Method according to claim 1, wherein the metal support is a sheet having a sheet thickness of 1 to 2.5 mm.

20. Method according to claim 1, wherein the hardenable coating has a thickness of 0.4 to 2 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The method according to the invention is shown in the figures, as an example. These show:

(2) FIG. 1 a method sequence with a fiber-reinforced plastic (FRP) laid onto a metal support,

(3) FIG. 2 a method sequence with a metal support, having applied fiber-reinforced plastic (FRP), and

(4) FIG. 3 a partial sectional view of a component shown according to FIGS. 1 and 2.

WAY TO IMPLEMENT THE INVENTION

(5) According to the method sequence 1 for the production of a component 2 shown in FIG. 1, a hardenable coating 6 with fiber-reinforced plastic (FRP), is applied to a metal support 3, which is cut off from a coil 4 of steel sheet 5, in a first step. The metal support 3 is possibly still cleaned or chemically pretreated beforehand, on this side to be coated, but this has not been shown in any detail. A robot 7 is provided for application of the coating 6, which robot picks up a cut-to-size piece 8 from the robot 9. For this purpose, the robot 9 cuts a woven fabric 10 pre-impregnated with the plastic matrix to size, in accordance with the surfaces of the regions of the metal support 3 that are to be coated. The coated metal support 3 is subsequently subjected to partial hardening, using a drying or hardening apparatus 11, after which the coating 6 forms at least one block-resistant surface 12. As a result, the metal support 3 can be easily laid also onto a stack 13, and thereby be stored temporarily or prepared for further transport, for example. Particularly, however, it can be made possible, in this way, to enable the coated metal support 3 to be formed into a component 2, in a further step, because its coating 6 has hardened to form at least one block-resistant surface 12. Therefore, the coated metal support 3 is introduced into a deep-drawing tool 14 and formed. Because the metal support 3 is coated on one of its metal support sides at most in certain regions, as can be seen in FIG. 1, comparatively great plastic formability of the metal support 3 can also be ensured. Therefore even great degrees of forming can be fulfilled without failure, as can be required, for example, in the case of a rocker panel or side member of a motor vehicle.

(6) As can also be seen in FIG. 1, a coating-free region 15 is provided everywhere where the metal support 3 is subject to plastic forming by means of deep-drawing. However, further coating-free regions can be present on the metal support 3, in accordance with the requirements.

(7) In contrast to the method 1 shown according to FIG. 1, the method 16 according to FIG. 2 has a different manner of application of a coating 17 to the metal support 3. Resin 18 and hardener 19 are mixed with fibers 20, preferably long fibers, in a predetermined ratio, and applied to the metal support 3. Subsequently, as in FIG. 1, block-resistant hardening of the coating 17 takes place, using a drying or hardening apparatus 11. The coated metal supports 3 can then be laid onto a stack 13 again, or also can be immediately subjected to deep-drawing, using the deep-drawing tool 14, which is not shown in any detail.

(8) According to FIG. 3, it can be seen that the metal support 3 has coating-free regions 15 that absorb the plastic changes in shape of the metal support 3 during forming, which changes follow the forming radii 21, particularly bending radii. In this way, comparatively great plastic formability of the coated metal support 3 is guaranteed. The metal support furthermore has a metallic and/or organic protective coating 22, for example a zinc layer. Furthermore, an adhesion-promoting agent 23 is provided between the coating 6 and the protective coating 22. A parting layer 24 is also applied to the coating 6 or 7. It is advantageous that the method according to the invention can be used for optimization of the mechanical properties with regard to crash behavior, with regard to compression or bending behavior.

(9) In Table 1, the mechanical properties of non-coated and coated cap profiles were compared as examples.

(10) TABLE-US-00001 TABLE 1 Steel sheet Steel sheet with with pre- subsequently impregnated impregnated Steel sheet laid scrim laid scrim Fiber volume 40 to 70% 35 to 85% proportion in the polymer matrix Sheet thickness 1 mm 1 mm 1 mm Coating 1 mm 0.4 to 0.6 mm thickness Specific 100% >125% >120% absorbed energy during quasi- static axial compression Maximal force 100% >135% >120% during three- point bending Absorbed energy 100% >110% >120% during three- point bending

(11) For the different stresses, the following test setups were chosen: For quasi-static axial compression: approx. 50% of the surface with FRP reinforcement; For three-point bending: approx. 15% of the surface with FRP reinforcement;

(12) The quasi-static axial compression was carried out at a deformation speed of 30 mm/min, up to a deformation of 60%. The three-point bending test was carried out at a deformation speed of 30 ram/min, with a maximal displacement path of 250 mm.

(13) Despite partial coating of the cap profiles, significant improvements in the ability to withstand stress, as compared with a non-coated cap profile, are found, without a restriction of the degrees of forming that can be achieved having to be accepted as a result.

(14) In Table 2, the strength of a planar semi-finished product with different FRP coatings is compared with conventional steel sheets. The FRP coating has at least one block-resistant surface before the tensile test or bending test.

(15) TABLE-US-00002 TABLE 2 Steel sheet Steel sheet Steel sheet with with long with pre- subsequently fibers in Steel impregnated impregnated laid the polymer sheet laid scrim scrim matrix Fiber volume 40 to 70% 35 to 85% 15 to 50% proportion in the polymer matrix Sheet thickness 1 mm 1 mm 1 mm 1 mm Coating 1 mm 0.4 to 0.6 mm 0.5 to 2 mm thickness Strength during 100% >195% >210% (one ply) >145% the tensile (one ply) >270% (two test plies) Absorbed energy 100% >231% >157% (one ply) >176% during three- >209% (two point bending plies) Specific 100% >191% >151% (one ply) >158% absorbed energy >180% (two during three- plies) point bending

(16) Hardening of the FRP coating took place between 20 and 130 C. for 120 to 500 minutes. Preferably, in the case of pre-impregnated laid scrim, between 90 and 130 C. for 90 to 180 minutes, and, in the case of subsequently impregnated laid scrim and when using long fibers, between 20 C. and 60 C. for at least 480 minutes.

(17) The ratio of metal support thickness to coating thickness has proven to be advantageous in a range of 1:2 to 1:0.4, in the examples. The steel sheet thickness or sheet thickness of the metal support material, in each instance, can also be varied; the invention can distinguish itself, in particular, at a metal support thickness in the range of 0.6 to 5 mm, particularly 1 to 2.5 mm.

(18) In total, it has thereby been shown that it was possible to increase the strength by 10 to 20%, surprisingly already with relatively thin FRP layers in the range of 0.2 to 3 mm, particularly 0.4 to 2 mm coating thickness. A total weight saving, for example of a rocker panel or side member, in the range of above 10% can certainly be achieved in this way. This advantageously results in a lower vehicle body weight and thereby lower total vehicle weight, which is also reflected in lower fuel consumption.