EP2432605A1

EP2432605A1 - Method for producing a metal component from a hot-stamped raw material

Info

Publication number: EP2432605A1
Application number: EP10719007A
Authority: EP
Inventors: Franz-Josef Lenze; Sascha Sikora; Andreas Ulrichs; Lothar Patberg
Original assignee: ThyssenKrupp Steel Europe AG
Current assignee: ThyssenKrupp Steel Europe AG
Priority date: 2009-05-18
Filing date: 2010-05-14
Publication date: 2012-03-28
Also published as: US20120074733A1; CN102427898A; WO2010133526A9; US8434231B2; WO2010133526A1; DE102009025821A1; CN102427898B; DE102009025821B4

Abstract

The invention relates to a method for producing a metal component, wherein a raw material (4, 34, 42, 74) is provided, the raw material (4, 34, 42, 74) is stamped and is further processed following the stamping process to form a component (90, 108, 114). The component (90, 108, 114) has at least partially stamped areas (16, 36, 48, 98), and the raw material (4, 34, 42, 74) is hot-stamped. The invention further relates to the use of a hot-stamped metal component, which is preferably produced using a method according to the invention, in a motor vehicle body, in particular as a reinforcing element in a B-column (114), a sill, or a longitudinal beam.

Description

METHOD FOR PRODUCING A METAL COMPONENT FROM A HOT-EXPRESSED STARTING MATERIAL

The invention relates to a method for producing a metal component, in which a starting material is provided, the starting material is stamped and further processed after being stamped into a component, wherein the component has at least partially embossed regions. The invention also relates to an advantageous use of a metal component produced in this way.

Under a starting material is understood in the context of this invention, a board, a semi-finished product or a band of metal. In the production of metal components, in particular of body components, the manufacturing process must meet various requirements. So it is particularly important in the production of body parts to meet the required strength properties with the lowest possible component weight and on the other to minimize manufacturing costs. In order to meet these requirements, in manufacturing processes for metal components or

Prior art body components pursued various strategies.

One way to reduce component weight while maintaining the same strength is to use variable wall thicknesses within a component. So will in the

DE 10 2007 030 388 A1 discloses a method and an apparatus for producing a hardened sheet-metal component which flexibly rolled materials, so-called tailored rolled blanks, are used. Alternatively, also welded together boards of different wall thickness, so-called "Taiiored Welded Blanks" can be used for the production of metal components. Another way to optimize the weight of body parts from the prior art is the use of embossed sheets. In this process, a board is cold rolled between two rolls in the cold state. At least one of the rollers has the structure required for the embossment on the

Surface on. The material used can be supplied to the rolls as a coil or cut to length as a single board. After embossing, the material is usually packaged and transported to the processing location. In order to provide crash-optimized components, among other things on

Processing site, the structure of cold-rolled stamped boards are changed. This is done for example by a local heat input. The disadvantage of these methods from the prior art is that the manufacturing costs of crash-optimized components are increased. Furthermore, due to the cold embossing rolling increased wear of the rollers due to high rolling forces.

The invention is therefore the technical object of providing a method in which the manufacturing cost of crash-optimized components are reduced and at the same time a reduced wear of the rollers occurs.

This is inventively achieved in a generic method in that the starting material is heat stamped. It has been recognized that the hot stamping of the starting material requires substantially lower forces for introducing the stampings. In hot embossing, the board is previously heated to a temperature above ACi temperature, ie more than 723 ⁰ C and then embossed. This ensures that takes place before stamping an at least partial structural transformation of the board in austenitic structure. Austenitic structure requires less forming forces. The contact pressure of the press or the embossing roller is therefore lower, so that the press or roller and the associated drive need only be designed for lower forces and wear less. This leads to a cost reduction of the method over the stamping method of the prior art.

In a preferred embodiment of the method, the starting material is heat-pressed with a roller. The use of a roll for hot stamping has the advantage that the stamping is continuously possible and thus this step of the manufacturing process can be better integrated into a process flow.

It has been found that particularly low forces are sufficient for good embossing results, if that

Starting material is warm prominently above AC ₃ . In this case, there is a complete austenitic structure, so that a complete microstructure transformation into martensite can take place during hot stamping. This results in particularly high strength of the board after hot stamping. In a further preferred embodiment of the method according to the invention, the starting material cures at least partially in the embossed region. The contact of the roller with the starting material in the region of the embossment leads to a cooling of the hot metal, if the temperature difference between the roller or embossing punch and the starting material is large enough. As a result, a structural change can be effected so that a hardening process occurs, in particular in the reason of the stampings. Thus, it is possible to easily produce metal components with local hardness differences, for example, have a crash-optimized strength profile.

The cooling may be in a further preferred

Embodiment of the method can be selectively optimized by the embossing tool, that is, the embossing roll or the die, is actively cooled during rolling. As a result, in particular the cooling rate and thus the degree of hardening can be adjusted.

A further preferred embodiment of the method according to the invention is given by the fact that the starting material consists of a steel alloy, in particular a manganese-boron steel. With these materials, the requirements for body components in the automotive industry can be met particularly well. Furthermore, in particular, the manganese-boron steel has a particularly high strength.

The properties of the metal component, such as the

Corrosion resistance can be specifically adjusted in a further preferred embodiment that the Äusgangsrα material is coated metallic or organic / inorganic.

A further reduction of the production costs is achieved in a further embodiment in that the starting material after the embossing to the processing temperature for the following

Further processing is tempered. The heat energy that was required for tempering the metal component for the hot stamping process can thus be used at least partially for subsequent processing. Thus, for further processing, the metal component does not have to be heated from, for example, room temperature to the processing temperature, but only from the temperature after being applied to the processing temperature. This leads to a significant energy saving.

A further preferred embodiment of the method according to the invention is provided in that the starting material is hot-formed and / or press-hardened after stamping. The processing temperatures required for hot working or press hardening are in a similar range as the preferred embossing temperature. Therefore, after embossing, very little energy is required to bring the embossed semi-finished product to the desired processing temperature. Furthermore, by hot forming high degrees of deformation can be achieved and the component can be converted very flexible.

By the press-hardening of the embossed metal component, a different hardness distribution in the metal component can be brought about by virtue of the fact that the non-embossed regions have direct contact with the surface of the press-hardening tool and thus cool faster than the embossed areas. This can on the one hand be achieved that the non-embossed areas have a higher hardness than the embossed areas, on the other hand, in combination with the partial hardening of the embossed areas during the Verprägevorgangs a different or similar curing in the embossed and non-embossed area can be achieved.

In a further preferred embodiment of the method according to the invention, the starting material is embossed with a microstructure. In this way, particularly homogeneous properties, in particular strength and hardness properties of the metal component are achieved. In addition, microstructured embossments can provide a good combination of high strength and high weight reduction. The microstructure may have any conceivable and practical form / design. For example, it is conceivable to emboss a microstructure with a surface roughness Ra of 50 μm to 500 μm.

In a further embodiment, a very flexible composite component is achieved in that a circuit board is used as the starting material and the circuit board after the circuit board

Verprägen surface is connected to another board, preferably on the embossed side is connected. These blanks are then preferably joined together by plating rolling and / or hot-forming together. During plating rolling, the blanks can be connected to one another in a material-locking manner without forming a positive fit. At the common Hot forming results in a positive connection, which connects both boards to form one component. Optionally, air gaps between the embossed boards can be provided, with which an improvement of the elongation capacity of the component is achieved. However, a compound can also be implemented by known methods, for example using solders. Particularly flexible properties are achieved in the production of the previously described component in that the two boards are made of different materials.

In a further embodiment of the method according to the invention, the starting material is specifically embossed in the regions which contribute to the weight reduction. In this way, the production of components is possible, which have a lower weight at approximately the same strength.

In a further preferred embodiment of the method, the starting material is deliberately loaded in accordance with load, in particular with regard to the crash behavior. Due to the material thinning achieved with the embossing and / or the hardness distribution in the component achieved during embossing or by subsequent process steps, it is possible to determine the hardness and / or hardness

Depending on the location, the strength properties of the component can be adjusted by the respective expected load, in particular in the case of a crash.

The technical problem is solved in a second teaching in that a hot-pressed metal component, preferably produced by the production method according to the invention, is used in a motor vehicle body, in particular as a reinforcing element in a B-pillar, a sill or a longitudinal member. Due to the hot embossing, the characteristic properties of crash-optimized components can be set in a simple manner.

Further features and advantages of the invention can be taken from the following description of exemplary embodiments. Reference is made to the attached drawing. In the drawing show:

1 shows a first embodiment of the method according to the invention,

2 shows a second embodiment of the method according to the invention,

OFig. 3 shows a third embodiment of the method according to the invention,

4 shows a fourth embodiment of the method according to the invention,

5 shows a fifth embodiment of the method according to the invention,

Fig. 6 shows a sixth embodiment of the method according to the invention and

Fig. 7 shows an embodiment of the inventive use. In Fig. 1, a first Ausführungsbeispiei of the method according to the invention is shown. In the method 2, a circuit board 4 is initially provided as the starting material. Instead of a circuit board could here and in the other embodiments, a semi-finished example, a "tailored blank" or a band can be used.

The board 4 is tempered for hot stamping and therefore preferably has a temperature above the AC ₃ - temperature. The circuit board 4 in the present embodiment consists of a manganese-boron steel and is heated to a temperature of 900 to 950 ⁰ C. After heating, the board 4 is heat embossed in a rolling stand 6. The rolling stand has an upper roll 8 and a lower roll 10, wherein the upper roll 8 has a surface structured for embossing. This is shown schematically in Fig. 1 by bulges 12. After hot embossing, the embossed board 14 has embossments 16 introduced by the bulges 12.

The rolling stand 6 is shown only schematically, ie it is not limited in particular to two rollers. It can also be configured as a quarto or sexto arrangement. The stampings 16 can be introduced into the board 14 by a plurality of Verpragewalzen or by a Verprägestempel. The stampings 16 can also be introduced on both sides of the board 14, for example, if the lower roller 10 has bulges. After the heat embossing process, the embossed board 14 or the folded semi-finished product is further processed in a further working step 18 to form a component. This further Step 18 may include in particular forming operations, press hardening operations, but also chip and joining operations.

In Fig. 2 is another embodiment of a

Walzstandes 26 shown for the hot stamping of the starting material. The rolling stand 26 has an upper roll 28 and a lower roll 30. To the surface of the upper roller 28 are arranged parallel bulges 32, with which the board 34 is stamped during hot rolling. The embossed board 34 has thereby after the hot rolling strip-shaped stampings 36. The method is, however, in principle not limited by the shape of the stampings.

Fig. 3 shows a sectional view of such a heat embossing operation. The board 42 is stamped by the upper roller 44, which is only partially shown in Fig. 3, by means of the Auswöibungen 46 present on the surface. The lower roller is not shown for reasons of clarity. In the stamping process, a bulge 46 of the roller 44 presses an embossment 48 into the board 42. The board 42 may have a temperature above the AC ₃ temperature before embossing and may be cooled by contact with the profiles 46 in the base 50 of the embossment 48 become. In this way, partial hardening or complete hardening of the board in the region of the stamping reason 50 can occur.

This effect can be enhanced by actively cooling the upper roll 44. For this purpose, the roller 44, for example, a liquid cooling system in its interior exhibit. The depth of the Verpragungen 48 is dimensioned in Fig. 3 so that the intermediate portion 52 of the roller 44 is not in direct contact between the bulges 46 with the board 42. As a result, a strong cooling of the areas 54 of the board 42 lying between the depressions 48 is avoided, so that the board experiences essentially no structure change, in particular no hardening, in this area. In this way, a different hardness distribution in the embossed and non-embossed areas of the board 42 can be achieved. A particularly homogeneous structure of the board 42 can optionally be achieved in that the board 42 is embossed with a microstructure.

Fig. 4 shows a flowchart of another

Embodiment of a method according to the invention. In the method 60, in a first step 62, a starting material, ie a circuit board, a semifinished product or a strip is provided and tempered to the temperature for hot stamping. This temperature is preferably above the AC ₃ temperature of the starting material. In the next step 64, the starting material is then hot stamped, in particular with a roller or a punch. In the embossing process, a part of the starting material can harden, for example in the embossed region by the contact with the roller or with the stamp.

After the stamping process, the starting material usually has a temperature which is far above the room temperature. In the following step 66, the embossed starting material for the further processing planned in the following step 68 is tempered. It will takes advantage of the fact that the already increased temperature of the starting material after hot stamping requires less energy to bring the starting material up to the processing temperature than cold-stamped blanks.

In particular, after the embossing, the starting material may at least partially still have a temperature above the ACi temperature. For a further processing temperature above the ACi temperature required in the subsequent step 68, only a small temperature control of the starting material is required. A processing temperature above the ACi temperature is needed in particular during hot forming and press hardening. Therefore, the starting material is preferably hot worked or press cured in step 68.

If the embossed starting material is designed as a circuit board, then this board can optionally also be connected to another cold or warm board, preferably on the embossed side.

In Fig. 5a a embossed board 74 is shown with Verprägungen 76 on the top. On this embossed board another board 78 is applied, which with the

Board 74 in the non-embossed areas 80 is in contact. If a cold board 78 is connected to the embossed board 74, this can lead to a hardening of the non-embossed areas 80 of the embossed board 74 as a result of the associated cooling. The boards 74 and 78 can be connected to each other, for example by material bonding, in particular by welding. This way will a flexible composite member 82 made. The air gaps between the boards 74 and 78 in the region of Verpräσungen 76 can contribute specifically to an improvement in the elongation of the component 82.

By selecting different materials for the boards 74 and 78, in particular different steel alloys with different properties in terms of strength and hardness, different components 82 can be made in a very flexible manner.

Instead of a cohesive connection between the boards 74 and 78, it is also possible to connect the boards by a rolling process or by joint forming together to form a positive connection. In Fig. 5b, the embossed board 74 and the other board 78 is shown after a common forming process. The two boards 74 and 78 are positively connected by the forming process in their common investment area and / or non-positively. In this way, a complex formed composite component 90 can be produced without an additional welding operation.

FIGS. 6a to 6c show a further exemplary processing step of a hot-stamped starting material designed as a printed circuit board. The hot-stamped circuit board 96 has embossed regions 98 and non-embossed regions 100. The temperature of the embossed board 96 is above the ACi temperature preferably above AC ₃ . The board is placed in a tool 102, consisting of an upper tool 104 and a lower tool 106, and there hot-formed into a component 108 and press hardened. During the press hardening process, the component 108 is not in direct contact with the upper tool 104 in the embossed regions 98. The cooling rate in these regions 98 is thus lower than in the embossed regions 100. Consequently, in these regions 98 there is no structural change of the component 108, so that the component 108 is cured only in the non-embossed regions 100.

This manufacturing method can be advantageously combined with the partial curing of the embossed board during hot stamping. By partially hardening the board in the embossed area by the contact with the roller or with the die during the hot stamping and the maps of the non-embossed areas in the press hardening tool 102, the embossed and non-embossed areas can be hardened differently either or equally by different cooling rates, so that a variety of locally different hardness properties of the component thus produced is possible.

Finally, FIG. 7 shows an exemplary embodiment for an advantageous use of a hot-stamped metal component as B pillar 114. The B pillar 114 has a pillar region 116 and an upper connecting region 118 and a lower connecting region 120. In the production of body elements such as B-pillars there is a requirement to provide a high strength of the component at a low weight at the same time. On the one hand weight can be saved by the embossings introduced with the method, since in the area of the embossings a thinning of the material thickness occurs, and on the other hand the Strength or hardness can be adapted specifically to the load, in particular with regard to the crash behavior of the corresponding component, since the microstructural changes during the embossing or the subsequent method steps can locally adjust the properties of the component, for example in the connection region 120.

Claims

claims

Anspruch [en] A method of manufacturing a metal component, comprising providing a starting material (4, 34, 42, 74), embossing the starting material (4, 34, 42, 74) and becoming a component after being processed

(90, 108, 114) is further processed, wherein the component (90, 108, 114) at least partially embossed regions (16, 36, 48, 98), characterized in that the starting material (4, 34, 42, 74) hot embossed becomes.

2. Method according to claim 1, characterized in that the starting material (4, 34, 42, 74) is heat embossed with a roller (8, 28, 44).

3. The method according to claim 1 or 2, characterized in that the starting material [A, 34, 42, 74) is hot stamped above AC ₃ .

4. Method according to one of claims 1 to 3, characterized in that the starting material (4, 34, 42, 74) cures at least partially in the embossed region (16, 36, 48, 98)

5. The method according to any one of claims 1 to 4, characterized in that the embossing tool (8, 28, 44) is actively cooled during rolling.

6. Method according to one of claims 1 to 5, wherein the starting material (4, 34, 42, 74) consists of steel, in particular a manganese-boron steel, or of a steel alloy.

7. A process according to any one of claims 1 to 6, wherein the starting material (4, 34, 42, 74) is coated metallically or organically or inorganically.

8. Method according to one of claims 1 to 7, characterized in that the starting material (4, 34, 42, 74) is tempered after being applied to the processing temperature for the subsequent further processing.

9. Method according to one of claims 1 to 8, characterized in that the starting material (4, 34, 42, 74) is hot-formed after stamping and / or press-hardened.

10. The process according to claim 1, wherein the starting material (4, 34, 42, 74) is embossed with a microstructure according to one of claims 1 to 9, characterized in that the starting material (4, 34, 42, 74) is embossed.

11. The method according to any one of claims 1 to 9, characterized in that As Ausσangsmaterial a board (74) is used and the board (74) after the embossing surface is connected to another board (78) preferably on the embossed side.

12. The method according to claim 10, wherein the boards (74, 78) are joined together by plating rolling and / or by hot forming together.

13. Method according to claim 10 or 11, characterized in that the two boards (74, 78) consist of different materials.

14. Method according to one of claims 1 to 12, characterized in that the starting material (4, 34, 42, 74) is specifically embossed in the areas contributing to the weight reduction.

15. Method according to one of claims 1 to 13, characterized in that the starting material (4, 34, 42, 74) is stamped in a targeted manner, in particular with regard to the crash behavior.

16. Use of a heat-embossed metal component, preferably produced according to one of claims 1 to 15, in a motor vehicle body, in particular as Reinforcement element in a B-Säuie (114), a rocker or a side rail.