METHOD FOR HOT FORMING THIN SEMI-FINISHED PRODUCTS

Abstract

The invention relates to a method for hot forming semi-finished products of steel, in which the semi-finished product is heated to the forming temperature, is conveyed to the forming tool, and in the forming tool is hot formed, hardened or press hardened. The object of proposing a method for hot-forming semi-finished products of steel, in which also extremely thin-walled blanks may be conveyed at the forming temperature without issues and be fed to the forming tool properly and without limiting the degree of forming of the semi-finished product, is achieved in that prior to hot forming, hardening or press hardening, at least one structure which increases rigidity at least is incorporated in the semi-finished product, and the structure which increases rigidity of the semi-finished product is at least partially or completely disposed in the trimming region of the semi-finished product.

Claims

1.-10. (canceled)

11. A method for hot forming a semi-finished product of steel, the method comprising: heating the semi-finished product to a forming temperature; conveying the semi-finished product to a forming tool; forming at least one structure in the semi-finished product that increases rigidity of the semi-finished product, the at least one structure being formed at least partially in a trimming region of the semi-finished product; and hot forming, hardening, or press hardening the semi-finished product in the forming tool after the at least one structure has been formed in the semi-finished product.

12. The method of claim 11 wherein the semi-finished product has a maximum wall thickness of 1.2 mm.

13. The method of claim 11 wherein the at least one structure comprises at least one of a depression or a pleat.

14. The method of claim 11 wherein the at least one structure comprises at least one chamfer of an edge of the semi-finished product.

15. The method of claim 11 wherein the at least one structure comprises at least one cutting burr on a cutting edge of the semi-finished product.

16. The method of claim 11 wherein the at least one structure comprises at least one beading on a periphery of the semi-finished product.

17. The method of claim 11 wherein the at least one structure comprises at least one stamping.

18. The method of claim 11 further comprising at least partially removing the at least one structure by trimming all or part of the trimming region during or after hot forming or press hardening.

19. The method of claim 11 further comprising at least partially removing the at least one structure by trimming all or part of the trimming region during or after hot forming, hardening, or press hardening.

20. The method of claim 11 wherein the semi-finished product is a cut-to-size blank.

21. The method of claim 11 further comprising forming the semi-finished product into an A-pillar, a B-pillar, or a C-pillar of a motor vehicle.

Description

[0015] The invention is to be described in more detail in the following by means of exemplary embodiments in conjunction with the drawing, in which

[0016] FIGS. 1 to 4 in a schematic and perspective illustration show four different exemplary embodiments of semi-finished products having a rigidity-increasing structure, in the trimming region,

[0017] FIG. 5 shows a plan view of a further exemplary embodiment of a semi-finished product having a rigidity-increasing structure; and

[0018] FIG. 6 in a plan view shows a vehicle component manufactured from the semi-finished product illustrated in FIG. 5, after trimming.

[0019] FIG. 1, in a perspective and schematic illustration, shows an exemplary embodiment of a semi-finished product 1 in the form of a blank which on the left side has a chamfer 2 and on the right side has a large cutting burr 3 for increasing rigidity. However, structures of an identical type for enhancing rigidity may be incorporated on both edges of the semi-finished product 1 illustrated. The trimming region of the plate 1 is illustrated using the dashed line 4. As may be readily seen, rigidity of the blank 1 is determined by the depth of the chamfer t, or the depth of the cutting burr 3, respectively, since the cutting burr 3 or the chamfer 2, respectively, also has to be bend in the case of bending which is perpendicular to the chamfer or the cutting burr, respectively. In this way, bending of the semi-finished product which is perpendicular to the chamfer or perpendicular to the cutting burr, respectively, is prevented in a simple manner. Not only the disposal of a chamfer 2 or of the cutting burr 3 in the direction of conveying R, but also so as to be perpendicular thereto, for example, is also conceivable. However, an exemplary embodiment corresponding thereto is not illustrated.

[0020] The cutting line 4 indicates the trimming region of the blank. Post forming, the rigidity-increasing structure 2, 3 is completely removed from the formed blank. In this way, it is also not necessary for corresponding regions or the entire rigidity-increasing structure to be deformed or to be re-flattened during the hot-forming process. The same also applies to the pleats 6 of the semi-finished product 5 of FIG. 2, which run in the direction of conveying R. As can be seen, the cutting lines 4 here also run in such a manner that the rigidity-increasing structures, here the pleats 6, are completely located in the trimming region. However, it is also conceivable for the finished component to have a corresponding region with a pleat 6, such that the rigidity-increasing structures 2, 3, 6 only have to be partially removed.

[0021] A measure which is similar to incorporating a pleat 6, a chamfer 2, or a large cutting burr 3, respectively, is achieved by a stamping 8 in the trimming region, as is shown by the blank 7 in FIG. 3. Here too, the cutting lines 4 mark the trimming region, on account of which it becomes clear that the stampings 8 which are provided with a greater wall thickness are disposed in the trimming region and thus post forming and trimming are no longer part of the formed component.

[0022] The same also applies to the beading 10 which in the exemplary embodiment illustrated in FIG. 4 have been incorporated on the periphery of the cut-to-size blank 9. As is also the case in the remaining exemplary embodiments above, the cutting lines 4 are illustrated using dashed lines, such that the beading 10 are located in the trimming region of the blank 9. Beadings 10 may be incorporated in a simple manner in a strip, for example by way of a roll forming method.

[0023] The exemplary embodiment of FIG. 5 is a plan view of a semi-finished product which is to be formed into a vehicle component, in the present exemplary embodiment into a part of a B-pillar of a motor vehicle. The semi-finished product 11 has a plurality of trimming regions which are defined by the lines 12, 13, 14. Pleats 15, on the one hand, and an elevated cutting burr 16 and 17, on the other hand, are provided in the trimming region. These serve for stiffening the blank 11, until being moved during trimming of the hot-formed, hardened, or press-hardened semi-finished product 11. A plan view of the formed semi-finished product 11 post trimming is illustrated in FIG. 6. The blank 11 has been formed into a part of a B-pillar of a motor vehicle. This also represents a typical application for hot-formed sheets, since particularly high strengths and at the same time low weights are required here. It is also conceivable for the semi-finished product 11 to be formed into parts of an A-pillar or a C-pillar of a motor vehicle or into another vehicle component, and then for the structures which increase rigidity of the semi-finished product to be at least partially removed from the semi-finished product by trimming.

[0024] Therefore, semi-finished products having a particularly large area and very thin wall thicknesses of maximum 1.2 mm, maximum 1.0 mm, maximum 0.8 mm, or maximum 0.5 mm may in particular be hot formed, hardened or press hardened, using the method according to the invention, without process-related issues arising on account of undesirable bending of the semi-finished products which have been heated to the forming temperature.