Method For Producing Hardened Steel Sheet Components

Abstract

The invention relates to a method for producing a hardened sheet steel component, wherein sheet steel sheet bars are cut from a coil made of a hardenable steel alloy or steel strip, formed into sheet steel component blanks in a cold forming process, and the blanks are heated in a continuous furnace to a temperature above the austenitization temperature required for the hardening and pressed and quench hardened in a form hardening tool. The blanks have point-shaped or linear beads, raised bumps, or flanges whose free ends or partial lengths are bent relative to the contact element so that the blanks rest on the contact element using only the point-shaped or linear beads, raised bumps, or free ends or partial lengths of the flanges. During form hardening, the beads, bumps or bends are pressed or deformed into the desired geometry of the finished component.

Claims

1-9. (canceled)

10. A method for producing a hardened steel sheet component, comprising the steps of: cutting steel sheet bars from a steel strip, or from a coil made of a hardenble steel alloy; cold forming the steel sheet bars into steel component blanks; conveying the blanks through a furnace on a contact element; heating the blanks in the furnace to a temperature above an austenization temperature; and pressing and quenching the blanks in a form hardening tool; wherein the blanks comprise at least one of point-shaped beads, linear beads, raised bumps, and flanges having free ends regions that are bent relative to the contact element; and the blanks rest on the contact element using only the point-shaped beads, linear beads, raised bumps, and/or free end regions of the flanges.

11. The method of claim 10, wherein the blanks comprise flanges having free end regions that are bent by about 2-10 degrees relative to a surface of the contact element.

12. The method of claim 10, wherein the blanks comprise flanges having free end regions that are bent by about 2-7 mm relative to a surface of the contact element.

13. The method of claim 10, wherein the contact elements comprise at least one of walking beams, chains, plates, and rollers.

14. The method of claim 10, wherein the contact elements comprise support strips.

15. The method of claim 10, wherein the blanks comprise point-shaped beads, linear beads or raised bumps that rest on the contact element.

16. The method of claim 15, wherein the point-shaped beads, linear beads or raised bumps protrude by about 2-7 mm toward the contact element.

17. The method of claim 10, wherein the steel strip or coil further comprises a metallic corrosion protection layer based on zinc, aluminum, or an alloy thereof.

18. The method of claim 10, wherein the steel strip or coil comprises a boron-manganese steel.

19. A method for producing a hardened steel sheet component, comprising the steps of: cutting steel sheet bars from a steel strip, or from a coil made of a hardenble steel alloy; cold forming the steel sheet bars into steel component blanks; forming deformations in the steel sheet blanks during the cold forming process conveying the blanks through a furnace on a contact element; heating the blanks in the furnace to a temperature above an austenization temperature; and pressing and quenching the blanks in a form hardening tool; wherein the blanks rest on the contact element using only the deformations, and the deformations are corrected in the form hardening tool.

20. The method of claim 19, wherein the deformations comprise at least one of point-shaped beads, linear beads, raised bumps, and flanges having free ends regions that are bent relative to the contact element.

21. The method of claim 19, wherein the deformations are formed such that less than about 5% of a surface area of the blanks rests on the contact element.

22. The method of claim 19, wherein the deformations comprise flanges in the blanks, the flanges having free end regions that are bent by about 2-10 degrees relative to a surface of the contact element.

23. The method of claim 19, wherein the deformations comprise point-shaped beads, linear beads or raised bumps in the blanks that rest on the contact element.

24. The method of claim 23, wherein the point-shaped beads, linear beads or raised bumps protrude by about 2-7 mm toward the contact element.

25. The method of claim 19, wherein the steel strip or coil comprises a boron-manganese steel.

26. The method of claim 25, wherein the steel strip or coil further comprises a metallic corrosion protection layer based on zinc, aluminum, or an alloy thereof.

27. A method for producing a hardened steel sheet component, comprising the steps of: cutting steel sheet bars from a steel strip, or from a coil made of a hardenble steel alloy; cold forming the steel sheet bars into steel component blanks; forming deformations in the steel sheet blanks during the cold forming process conveying the blanks through a furnace on a contact element; heating the blanks in the furnace to a temperature above an austenization temperature; and pressing and quenching the blanks in a form hardening tool; wherein the blanks rest on the contact element using only the deformations, and the deformations are formed such that less than about 5% of a surface area of the blanks rests on the contact element.

28. The method of claim 27, wherein the deformations are formed such that less than about 3% of a surface area of the blanks rests on the contact element.

29. The method of claim 27, wherein the deformations are formed such that less than about 1% of a surface area of the blanks rests on the contact element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The invention will be explained by way of example based on the drawings. In the drawings:

[0054] FIG. 1: is a very schematic depiction of the method sequence in form hardening;

[0055] FIG. 2: schematically depicts the support regions of a preformed component on a chain conveyor without the bent regions according to the invention;

[0056] FIG. 3: shows a very schematic depiction of the standing behavior of a preformed component on a chain conveyor with flanges that are bent according to the invention;

[0057] FIG. 4: shows an example of a component according to the invention on a chain conveyor;

[0058] FIG. 5: schematically depicts a top view of a component according to the invention with bent flange regions for producing a linear support during a passage through a lifting step conveyor furnace;

[0059] FIG. 6: schematically depicts a top view of a component according to the invention with bent flange regions for producing a linear support during a passage through a roller hearth furnace;

[0060] FIG. 7: schematically depicts a top view of a component according to the invention with bent flange regions for producing a linear support in a multi-layer chamber furnace.

DETAILED DESCRIPTION OF THE INVENTION

[0061] FIG. 1 is a very schematic depiction of the form hardening process in which sheet bars are first cut from a steel strip or steel coil, the sheet bars are then cold formed, and the cold formed blanks are then austenitized in a furnace. The austenitized blanks are then placed into the form hardening mold and are hardened therein, then removed from it, and, as a finished blank, undergo a possibly necessary surface conditioning.

[0062] FIG. 2 shows the support surfaces for such components on a chain conveyor, wherein the preformed component in this case is supported with the whole area of its flanges.

[0063] FIG. 3 is a very schematic depiction of an embodiment according to the invention in which the flanges are formed so that the component rests on the chain conveyor with only the edge regions of the flanges so that a whole-area contact and thus the blisters on the entire surface are avoided. Blisters possibly occurring anyway are not critical at this location since the edge regions are not relevant at least with regard to a welded connection.

[0064] FIG. 4 shows a component in which the flanges are deformed over a partial length in order to achieve a linear standing surface along the edge wherein partial lengths have the desired shape, e.g. flat and with transition regions between the bent and flat regions.

[0065] FIG. 5 shows a top view of a component according to the invention with a linear support in the passage through with a lifting step conveyor. The component shown in FIG. 4 corresponds essentially to the diagram in FIG. 5. In this case, the individual conveyor chains and the walking beams between them are visible. In this connection, the bent flange regions in this example have at least a length of CW, i.e. the distance between a chain and a walking beam, which is approximately 10 cm in this example. In this way, the support surface can be reliably reduced and instead of a flat support, it is possible to ensure an only linear support of the componentand this also only in the bent flange regions. The region B depicts the length of the bend flange region (only indicated on the left in FIG. 5). In this case, a linear support at the outer edges of the flanges is provided on both sides, i.e. in four regions in this example of a component. Naturally, depending on the component geometry, a support in fewer linear regions (for example three lines) or also more linear regions would also be possible.

[0066] FIG. 6 shows a top view of a component according to the invention with a linear support in the passage through a roller hearth furnace. As before, regions with bent flanges are shown again here, once again indicated with the letter B (only on the left). This region can advantageously exceed at least the length from one furnace roller to the next furnace roller (length FR).

[0067] FIG. 7 shows a top view of a component according to the invention with a linear support in a multi-layer chamber furnace. By contrast with FIGS. 5 and 6, in this case the schematic depiction does not show a continuous furnace, but rather a multi-layer chamber furnace (or single-chamber furnace). In this case, the region of the bent flanges can be selected to be smaller because of the stationary support. In particular, the region for the linear support can be selected to be any size down to the minimum width of the support strip (SS). In this example, 6 support lines are shown since it can possibly be advantageous, depending on the component geometry to also provide other support lines in the middle regions since deflections can occur, for example. This is independent of the furnace type, though, i.e. it can also be advantageous in continuous furnaces.

[0068] Naturally, point-shaped supports of this kind can also be achieved by bending only the edge region of the flange in the direction toward the chain conveyor or by producing beads, regardless of whether these are point-shaped beads or linear beads. According to the invention, all of these slight deformations can, while in the hot state, be bent into the desired state in the form hardening tool without the risk of microcrack formation.