Method for producing hot-formed components

Abstract

A method is provided for producing a hot-formed component, in particular a sheet-metal component made of steel, aluminum, magnesium or a combination of the materials. The method includes the acts of: heating a semifinished product, in particular a sheet-metal blank or a pre-shaped sheet-metal component, inserting the semifinished product into a molding tool, and quenching the semifinished product in the molding tool, wherein a change is made to the microstructure of the material at least in one portion. Before the insertion of the semifinished product into the molding tool, an insulating device is applied in at least one predetermined region of the semifinished product. The insulating device is connected in a form-fitting, integral and/or force-fitting manner to the semifinished product.

Claims

1. A method for producing a hot-formed component, the method comprising the acts of: heating a semi-finished product; prior to introducing the semi-finished product into a forming tool, applying insulating installation in the form of a permanent magnet to the semi-finished product in a form-fitting, materially integral, and/or force-fitting manner in at least one predetermined region of the semi-finished product; introducing the heated semi-finished product with insulation installation into the forming tool; and cooling the semi-finished product in the forming tool, wherein a cooling rate in a portion of the semi-finished product covered by the insulation material is such that an microstructure is formed in the portion covered by the insulation material is more ductile than a microstructure formed in a portion of the semi-finished product that is not covered by the insulation material.

2. The method according to claim 1, wherein the component is made of steel, aluminum, magnesium, or a combination of these materials.

3. The method according to claim 2, wherein the semi-finished product is a metal blank or a preformed sheet-metal component.

4. The method according to claim 1, wherein the insulating installation is disposed on the semi-finished product prior to heating.

5. The method according to claim 4, wherein the insulating installation is disposed on the semi-finished product prior to heating, and is removed from the semi-finished product post heating.

6. The method according to claim 4, wherein the insulating installation is disposed on the semi-finished product prior to heating, and is left on the semi-finished product post heating of the semi-finished product and during hardening.

7. The method according to claim 1, wherein the insulating installation is disposed on the semi-finished product prior to heating, and is removed from the semi-finished product post heating.

8. The method according to claim 1, wherein the insulating installation is disposed on the semi-finished product prior to heating, and is left on the semi-finished product post heating of the semi-finished product and during hardening.

9. The method according to claim 1, wherein the insulating installation is disposed on the semi-finished product post heating, and remains on the semi-finished product during hardening.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1a-1c illustrate method steps according to the first method variant.

(2) FIGS. 2a-2c illustrate method steps according to the second method variant.

(3) FIG. 3 illustrates an exemplary structural component.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) The method steps that are carried out in the case of direct hot-forming according to a first variant of the method are depicted in FIGS. 1a-1c. The heating step in which a semi-finished product 17, illustrated here as a metal blank, is heated is illustrated in FIG. 1a. Heating may be performed in an oven or with the aid of another heat source. The insulating installation 15 has already been attached to a predetermined position and shields a predetermined region of the metal blank 17. The heat, illustrated as s-shaped curved arrows, in this region reaches the metal blank 17 only to a comparatively minor extent, heating the latter in the predetermined region to a lower temperature than in the remaining regions of the metal blank 17.

(5) FIG. 1b shows a forming tool 10 which is employable in presses in order for sheet-metal blanks to be hot-formed into sheet-metal components 17. The forming tool 10 has a lower tool half 12u which sits on top of a base plate 11. The lower forming tool half 12u interacts with an upper forming tool half 12o. The mutually facing operating faces of the upper forming tool half 12o and of the lower forming tool half 12u are configured in a corresponding manner such that said faces function like a die and a ram of a pressing tool. In the case of the example illustrated in FIG. 1b, the tool half 12o is configured as a ram, and the tool half 12u is configured as a die. The upper and the lower forming tool half, in terms of the arrangement thereof, may be swapped without departing from the scope of the invention, so that the upper tool functions as the die, and the lower tool functions as the ram. The upper tool half 12o and the lower tool half 12u are movable in relation to one another. The forming tool halves 12o, 12u, illustrated in FIG. 1b, may be diverged and converged again. When the forming tool halves are being converged, the semi-finished product 17, i.e. a piece of sheet metal, or a sheet-metal blank 17, comes to lie between the forming tool halves, being encompassed and formed by the operating faces. The state illustrated in FIG. 1b corresponds to an opened position of the tool halves 12u, 12o, in the case of a forming procedure in which the component 17 has been completely formed and may be removed from the forming tool 10. In the illustration, the insulating installation 15 is removed from the sheet-metal blank 17 post heating.

(6) An insert 13, in which a cooling system which has a plurality of cooling ducts or cooling lines 14 is integrated, is provided in the lower forming tool half 12u. On the one hand, the use of inserts 13 of this type offers the advantage that various component contours may be pressed using one lower forming tool 12u, in that the insert 13 may be replaced according to the desired shape of the component. The cooling lines 14 run so as to be substantially parallel with the surface of the component 17, and thus also substantially parallel with the operating face of the forming tool halves 12u, 12o. The cooling lines 14 thus follow the component surface at a certain spacing therefrom into the insert 13 of the lower forming tool half 12u. Targeted cooling of the semi-finished product 17 in the region of the cooling ducts 14 is enabled by way of the cooling ducts, such that the component is hardened and a microstructure having high mechanical strength values is implemented in the component.

(7) The forming tool 10 known from FIG. 1b is illustrated in FIG. 1c, the former however being in a closed position. In this state, the sheet-metal part 17 has been formed and is being hardened. Herein, heat is extracted from the component 17 and discharged by way of the cooling ducts 14.

(8) A second variant of the method is illustrated in FIGS. 2a to 2c. In the case of this variant, the metal blank 17 is completely heated, as is illustrated in FIG. 2a. Prior to the metal blank 17 being introduced into the forming tool 10, the insulating installation 15 is applied in a predetermined region to the metal blank 17, for example on a lower side of the semi-finished product 17, i.e. on that side that faces the lower tool half 12u. Thereafter, the metal blank 17 having the insulating installation 15 disposed thereon is introduced into the forming tool 10, as is depicted in FIG. 2b. During forming and hardening, illustrated in FIG. 2c, the insulating installation 15 influences the heat exchange between the semi-finished product 17 and the tool 10. That region of the semi-finished product 17 in which the insulating installation 15 is disposed corresponds to a predetermined region in which high mechanical characteristic values are not desired. Instead, a region having comparatively high ductility is to be implemented here. By way of the insulating installation 15, the semi-finished product 17 in the predetermined region is subjected to slower cooling than in the remaining regions. On account thereof, a pearlitic-ferritic material microstructure that imparts higher ductility to the region is configured here.

(9) While FIGS. 1a to 1c and 2a to 2c describe the invention by means of the direct hot-forming method, the invention may also be applied in the indirect method. Herein, the sheet-metal blank is initially cold-formed to become a three-dimensional semi-finished product. The latter is thereafter heated and, without further forming or optionally with only minimum forming, is then hardened. Post cold-forming, the first or the second variant may be selectively applied as has been described above, wherein the insulating installation 15 prior to heating or prior to hardening is applied to a predetermined region of the three-dimensional semi-finished product.

(10) In the figures, only the lower tool half 12u is provided with cooling ducts 14. Alternatively, in further embodiments of the invention, the arrangement of cooling lines may also be disposed in the upper tool half 12o. In one further alternative embodiment, cooling ducts 14 may be provided in both the upper tool half 12o as well as in the lower tool half 12u.

(11) FIG. 3 shows a plan view of a lower tool part 12u of the forming tool 10. A semi-finished product 17 for producing a B-pillar 18 is configured here in an exemplary manner. The semi-finished product 17 is cut along the dashed contour in order to obtain the B-pillar 18 as a component. This may be selectively carried out prior to or post hot-forming. Alternatively, other vehicle components or structural vehicle components may also be produced. Such components may in particular be A-pillars or C-pillars, lateral roof rails, roof bows, sills, longitudinal beams or cross beams.

LIST OF REFERENCE SIGNS

(12) 10 Forming tool 11 Tool base plate 12u Lower tool part 12o Upper tool part 13 Tool insert 14 Cooling lines 15 Insulating installation 16 Component 17 Semi-finished product

(13) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.