METHOD FOR PRODUCING A MOTOR VEHICLE COMPONENT FROM A 6000 SERIES ALUMINUM ALLOY

Abstract

A method for producing a motor vehicle component from a 6000 series aluminum alloy including providing a blank made of a 6000 series aluminum alloy, rapid heating of the blank to a temperature between 450 deg. C. and 600 deg. C. at a heating rate of more than 15 K/s in a period of less than 20 seconds, ending the heating process and optionally homogenizing, if a grain size between 20 and 50 m has been produced, quenching the blank thus tempered, applying a lubricant, preferably at 20 deg. C. to 100 deg. C., forming the cooled blank in a forming tool, wherein the time between completion of the heating process and the start of the forming is less than 30 seconds, and aging.

Claims

1. A method for producing a motor vehicle component from a 6000 series aluminum alloy, comprising: providing a blank made of a 6000 series aluminum alloy; rapid heating of the blank to a temperature between 450 deg. C. and 600 deg. C. at a heating rate of more than 15 K/s in a period of less than 20 seconds; ending the heating process and homogenizing, if a grain size between 20 and 50 m has been produced; quenching the blank thus tempered; applying a lubricant at a temperature between 20 deg. C. to 100 deg. C.; forming the cooled blank in a forming tool, wherein the time between completion of the heating process and the start of the forming is less than 30 seconds: and, aging.

2. The method according to claim 1, wherein an aluminum alloy is used that comprises the following alloy elements, expressed in percent by weight: TABLE-US-00004 silicon (Si) 0.70 to 1.10, preferably 0.75 to 1.05 magnesium (Mg) 0.50 to 0.80 balance aluminum and impurities due to smelting.

3. The method according to claim 2, wherein the aluminum alloy further comprises at least one of the following alloy elements, expressed in percent by weight: TABLE-US-00005 copper (CU) 0.03 to 0.20 manganese (Mn) 0.10 to 0.20 chromium (Cr) 0.10 to 0.20 titanium (Ti) 0.010 to 0.030 iron (Fe) 0.10 to 0.25.

4. The method according to claim 2, wherein a relative ratio of the fractions in percent by weight of magnesium to silicon is from 5 to 7 up to 5 to 9.

5. The method according to claim 2, wherein the content in percent by weight of magnesium and silicon together is greater than or equal to 1.20 and less than or equal to 1.90.

6. The method according to claim 5, further comprising producing a yield limit Rp 0.2 of greater than 260 MPa, in particular, greater than 280 MPa.

7. The method according to claim 6, further comprising producing a tensile strength Rm of greater than 320 MPa.

8. The method according to claim 6, further comprising producing a ratio of yield limit to tensile strength of less than or equal to 0.95.

9. The method according to claim 8, wherein the blank is in the state F or T4 or T6 prior to heating.

10. The method according to claim 8, wherein the heating and/or quenching is partially carried out.

11. The method according to claim 10, further comprising heating and/or quenching the blank at varying contact pressure; or that the contact plates with different temperatures are used, so that during the thermal treatment different temperatures are produced in certain regions of the blank.

12. The method according to claim 11, wherein the heating is carried out by contact heating at a heating rate of greater than 20 K/s, preferably greater than 50 K/s.

13. The method according to claim 12, wherein for rapid heating and/or quenching, contact plates are used, and wherein the contact plates comprise a coating.

14. The method according to claim 1, wherein the heating, cooling and/or forming is carried out in multiple steps.

15. An aluminum alloy for producing a motor vehicle component, wherein the aluminum alloy comprises following alloy constituents, expressed in percent by weight: TABLE-US-00006 silicon (Si) 0.70 to 1.10, preferably 0.75 to 1.05 magnesium (Mg) 0.50 to 0.80 copper (CU) 0.03 to 0.20 manganese (Mn) 0.10 to 0.20 chromium (Cr) 0.10 to 0.20 titanium (Ti) 0.010 to 0.030 iron (Fe) 0.10 to 0.25 balance aluminum and impurities due to smelting, wherein a blank is heated at a heating rate of greater than 4 K/s and is quenched at a cooling rate of greater than 10 K/s and thereafter is cold formed into the motor vehicle component, wherein the forming is carried out within 30 seconds after heating.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] For an understanding of embodiments of the disclosure, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0039] FIG. 1 illustrates an arrangement for carrying out the claimed method with a temperature control station and a forming and trimming station;

[0040] FIG. 2 illustrates an alternative arrangement to FIG. 1;

[0041] FIG. 3 illustrates an alternative arrangement to FIG. 1;

[0042] FIG. 4 illustrates an alternative arrangement to FIG. 1; and,

[0043] FIGS. 5 to 7 illustrate metallurgical grinding patterns.

[0044] In the figures, the same reference signs are used for identical or similar component parts, even if a repeated description is omitted for reasons of simplification.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

[0045] Some embodiments will be now described with reference to the Figures.

[0046] FIG. 1 shows an arrangement 1 for carrying the method of the current disclosure. The arrangement 1 includes a combined temperature control station 2. In a first step I a heating process takes place. For this purpose contact plates 3 are provided that are heated by means of a heat source (not shown in detail); and the inserted blank 16 is heated by abutting contact by means of thermal conduction. Thereafter a blank, which has been placed into the respective step, is also shown for reasons of simplification. A second step II provides cooling plates 4. The cooling plates 4 comprise cooling channels 5 for conveying a cooling fluid. Thus, the heated blank is cooled by abutting contact in the second step. Both the contact plates 3 and the cooling plates 4 are mounted by means of springs 6. As a result, the effective contact time can be increased during the tool closing time or while carrying out the cycle, since the plates protrude in the closing direction of the tool. The contact pressure is also homogenized; and the press deflection is compensated for. Optionally after the quenching operation a lubricant application system 17 is provided, which applies a lubricant to the blank by, for example, spraying.

[0047] The blank, which has been heated in the first step I and quenched in the second step II, is then transferred to a third step III, a forming station 12, where a forming tool 7 is provided for a first forming of the motor vehicle component 8 to be produced. A subsequent fourth step IV may comprise a forming step; in addition or as an alternative, it may also comprise a perforation and/or trimming tool 9. As an alternative or in addition, a further forming may also take place in this combined perforation or trimming tool 9. At the end of the process the formed motor vehicle component 8 is obtained, which in this case is a formed motor vehicle component 8, which has a hat shape in the cross section, only for illustrative purposes. The motor vehicle component may be a motor vehicle pillar, a longitudinal member or a cross member or any other body component or structural component; as an alternative, it may also be a chassis component, an exterior skin component or add-on part of a motor vehicle. A transfer system for conveying the blank is not shown.

[0048] FIG. 2 shows an alternative to FIG. 1. The arrangement 1 is shown providing a heating station 10, a cooling station 11 and a forming station 12. In total, a six-step tempering and forming process is carried out, wherein in the first two steps I+II the blank is heated in the heating station 10. Then this heated blank 16 is transferred to a cooling station 11 and is quenched in the cooling station 11 in step III and step IV. Then in a fifth step V the blank 16, which has been heated and thereafter quenched, is transferred to a forming tool 7, where the blank is formed in at least one step and optionally is formed once again as well as trimmed and perforated in a sixth step VI. Between step IV and V the lubricant is applied, for example, by means of two-sided spraying. This application of the lubricant can take place with the lubricant application system 17. Obtained is a motor vehicle component 8, which is also configured in a hat shape in the cross section, shown here merely for illustrative purposes.

[0049] FIG. 3 shows an alternative arrangement, where once again there is a temperature control station 2, which both heats and cools. The process is shown in seven steps. The first four steps are carried out in the temperature control station 2. For this purpose the blank is heated in step I and step II. Then in steps III and IV a quenching operation takes place. Then the blank, which has been tempered in this manner, is transferred to a forming station 12, where it is formed as well as trimmed and perforated in the next three steps V-VII. Between step IV and V a lubricant is applied, for example, by means of two-sided spraying.

[0050] FIG. 4 shows an alternative design variant, where a joint temperature control and forming station 13 is shown. This means that all of the contact plates 3, the cooling plates 4, the forming tool 7 and the perforation and trimming tools 9 are suspended from or fixed to a press upper part 14 and a press lower part 15. A closing movement of the temperature control and forming station 13 requires that all of the steps I-VII be carried out simultaneously. Here, too, springs 6 are provided again, so that the effective contact time of contact plates 3 and cooling plates 4 during the movement of the, for example, upper tool 14 to the lower tool 15 is increased. Furthermore a lubricant application system 17 is shown here in the first forming step V. The lubricant application system applies lubricant to the forming dies 18 of the forming tools 7.

[0051] FIG. 5 shows a metallurgical grinding pattern of a blank made of the aluminum alloy, described in accordance with the invention, in the provided state. A laminar structure can be seen here.

[0052] If at this point an inventive rapid heating is carried out with subsequent quenching, then the result is the material structure shown in FIG. 6, where it can be seen that individual grains, each exhibiting a grain size between 20 and 50 m, have formed. The sizes specified herein refer to both an extent of the length and width in the image plane as well as an extent of the height into or out of the image plane. Thus, the grain size is configured to be equiaxial. After the subsequent forming, the grain size is configured to be more or less identical. Depending on the quenching occurring inside the wall thickness during the forming operation, the orientation of the grains is slightly distorted.

[0053] In contrast to FIG. 6, FIG. 7 shows a material structure, produced with slower and longer heating as well as slower and longer cooling, each lasting several minutes. It is apparent that a much larger grain size and also a grain structure other than that shown in FIG. 6 have been produced.

REFERENCE NUMERALS

[0054] 1 arrangement [0055] 2 temperature control station [0056] 3 contact plates [0057] 4 cooling plates [0058] 5 cooling channels [0059] 6 springs [0060] 7 forming tool [0061] 8 motor vehicle component [0062] 9 perforation/trimming tool [0063] 10 heating station [0064] 11 cooling station [0065] 12 forming station [0066] 13 temperature control and forming station [0067] 14 press upper part [0068] 15 press lower part [0069] 16 blank [0070] 17 lubricant application system [0071] 18 forming dies