Method for Hot Forming a Semifinished Product, in Particular in Sheet Form

Abstract

A method for hot forming a semifinished product in sheet form for a motor vehicle component. The method includes heating the semifinished product to be formed in a heating process and forming the heated semifinished product in a shaping forming process. During the heating process the semifinished product undergoes an input of heat from at least one heat source. During the heating of the semifinished product, a shielding device is arranged between the heat source and the semifinished product, such that the semifinished product is thermally shielded at least in certain portions in such a way that a first semifinished-product portion is heated differently than a second semifinished-product portion.

Claims

1.-14. (canceled)

15. A method for hot forming a semifinished product in sheet form for a motor vehicle component, the method comprising heating the semifinished product to be formed in a heating process, wherein during the heating process the semifinished product undergoes an input of heat from at least one heat source; and forming the heated semifinished product in a shaping forming process, wherein during the heating of the semifinished product, a shielding device is arranged between the heat source and the semifinished product, such that the semifinished product is thermally shielded at least in certain portions in such a way that a first semifinished-product portion is heated differently than a second semifinished-product portion.

16. The method according to claim 15, wherein during the heating, the semifinished product is thermally shielded at least in certain portions by the shielding device in such a way that a first semifinished-product portion has a temperature in a first temperature range and a second semifinished-product portion has a second temperature in a second temperature range which differs from the first temperature range, the first temperature range is in the range of from 750° C. to 1100° C., and the second temperature range is in the range of from 500° C. to 950° C.

17. The method according to claim 16, wherein the at least one shielding device is formed at least in certain portions from a thermally insulating material and/or from a thermally insulating material structure, the shielding device being formed at least in certain portions from a material and/or a material structure having a thermal conductivity in the range of from 0.03 W/mK to 0.25 W/mK, at an average temperature of 800° C. and/or a material and/or a material structure having a linear shrinkage behavior of less than 8% at 1100° C. after 24 hours.

18. The method according to claim 17, wherein the at least one shielding device is formed at least in certain portions from natural fibers and/or synthetic fibers of inorganic materials.

19. The method according to claim 18, wherein the at least one shielding device is formed at least in certain portions from a porous material and/or from a porous material structure.

20. The method according to claim 19, wherein the at least one shielding device has at least a first shielding portion with a first heat shielding property and a second shielding portion having a heat shielding property which differs from that of the first shielding portion, and the different heat shielding property is distinguished by a different thermal insulation property and/or a different heat storage property and/or a different thermal conduction property.

21. The method according to claim 20, wherein the at least one shielding device is used which has at least a first shielding portion with a first shielding means receiving unit for receiving a first shielding means and at least a second shielding portion with a second shielding means receiving unit for receiving a second shielding means, the at least two shielding means being formed differently in terms of their material and/or material structure and/or arrangement and/or volume and/or weight and/or geometry.

22. The method according to claim 21, wherein during the heating of the semifinished product, the at least one shielding device thermally shields the semifinished product at least in certain portions on a top side and at least in certain portions on a bottom side, the shielding device thermally shielding the semifinished product in a congruent and/or oppositely situated shielding region on its top and bottom side.

23. The method according to claim 22, wherein the at least one shielding device has a c-shape form and two free limbs of the c-shaped shielding device are spaced apart by at most 15 mm, and the semifinished product is arranged at least in certain portions in an interior space of the c-shaped shielding device during the heating in the heating process.

24. The method according to claim 23, wherein the semifinished product is fed to a heating region such that the semifinished product rests on a grid-like product carrier, and the semifinished product is heated in the heating region, the shielding device being fastenable to the product carrier via a fastening device in releaseable fashion, so that the shielding device is fastenable in the manner of a grid pattern to at least two regions of the product carrier temporarily.

25. The method according to claim 24, wherein the at least one product carrier comprises at least one shielding device receiving device, into which a shielding device is receivable at least temporarily, the shielding device receiving device being arranged and/or formed in such a way that thermal expansion of at least one shielding device received in the shielding device receiving device is reduced or prevented.

26. The method according to claim 25, wherein the semifinished product has a thickness of from 0.1 mm to 4.0 mm.

27. The method according to claim 26, wherein the semifinished product is formed at least in certain portions from a metal, including at least one of a steel and a hot-forming steel.

28. A shielding device for thermally shielding a semifinished product at least in certain portions for a hot forming method according to claim 27.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a basic illustration of a product carrier, a shielding device and a heating table;

[0024] FIG. 2 is a basic illustration of a shielding device arranged on a product carrier; and

[0025] FIG. 3 is a basic illustration of a semifinished product arranged in an interior space of a shielding device.

DETAILED DESCRIPTION OF THE DRAWINGS

[0026] The figures show basic illustrations of the essential parts of an exemplary apparatus for carrying out a method for hot forming a semifinished product 1, in particular in sheet form, to afford a component (not illustrated), in particular a motor vehicle component, comprising (a) heating the semifinished product 1 to be formed in a heating process, wherein during the heating process the semifinished product 1 undergoes an input of heat 2, 2′ (indicated in the figures as thermal rays) from at least one heat source 3, 3′ and (b) forming the heated semifinished product 1 in a shaping forming process (not illustrated), wherein, during the heating of the semifinished product 1, a shielding device 4 is arranged between the heat source 3, 3′ and the semifinished product 1 such that the semifinished product 1 is thermally shielded at least in certain portions in such a way that a first semifinished-product portion 5 is heated differently to a second semifinished-product portion 6. The heat sources 3, 3′ are schematically illustrated in the figures and can extend preferably over or else beyond the entire length 7 of the semifinished product 1 and/or over or else beyond the entire length 8 of a heating table 9. During the heating, the semifinished product 1 is thermally shielded at least in certain portions by the shielding device 4 in such a way that a first semifinished-product portion 5 has a temperature in a first temperature range and a second semifinished-product portion 6 has a second temperature in a second temperature range which differs from the first temperature range, preferably the first temperature range is in the range of from 750 to 1100° C., preferably in the range of from 775 to 1050° C., particularly preferably in the range of from 800 to 975° C., and the second temperature range is in the range of from 500 to 950° C., preferably in the range of from 600 to 950° C., particularly preferably in the range of from 650° C. to 850° C. In this respect FIG. 3 illustrates that a first semifinished-product portion 5 is heated directly and thus without a shielding device 4 by the heat sources 3, 3′, whereas the second semifinished-product portion 6 is thermally shielded on both sides by the shielding device 4 with respect to the heat sources 3, 3′. Consequently, after the heating, the first semifinished-product portion 5 has a higher temperature than the second semifinished-product portion 6.

[0027] The at least one shielding device 4 is formed at least in certain portions from a thermally insulating material and/or from a thermally insulating material structure. In particular, the shielding device 4 is formed at least in certain portions from (a) a material and/or a material structure having a thermal conductivity in the range of from 0.03 to 0.25 W/mK, preferably in the range of from 0.08 to 0.20 W/material constituent, particularly preferably in the range of from 0.11 to 0.15 W/mK, at an average temperature of 800° C. and/or (b) a material and/or a material structure having a linear shrinkage behavior of less than 8%, preferably of less than 6%, particularly preferably of less than 4%, at 1100° C. after 24 hours.

[0028] The shielding device 4 can be formed at least in certain portions from fibers, preferably the shielding device 4 comprises at least in certain portions natural fibers and/or synthetic fibers, particularly preferably the shielding device 4 comprises at least in certain portions fibers of inorganic materials. Inorganic fibers of this type can comprise, for example, at least in certain portions ceramic fibers, quartz fibers, glass fibers, basalt fibers, carbon fibers, in particular composed of silicate fibers, and/or a glass fiber material. The shielding device 4 can be formed at least in certain portions from a porous material and/or from a porous material structure.

[0029] By way of example, the at least one shielding device 4 can have at least a first shielding portion 10 with a first heat shielding property and a second shielding portion 11 having a heat shielding property which differs from that of the first shielding portion 10. In the exemplary embodiments illustrated in the figures, the shielding device 4 has three shielding portions 10, 11, 12 arranged or formed next to one another. These shielding portions 10, 11, 12 can preferably be distinguished by different heat shielding properties (e.g. by different thermal insulation properties and/or different heat storage properties and/or different thermal conduction properties). This makes it possible to achieve the situation in which the regions of the semifinished product 1 arranged between the respective shielding portions 10, 11, 12 undergo different degrees of heating by the heat source 3, 3′ and thus a targeted heating of the respective regions and ultimately a targeted influence of the properties, in particular the material properties, of the respective regions can be achieved. In the embodiment illustrated, the shielding device 4 extends over the entire width 26 of the semifinished product 1; it can also be expedient that the shielding device 4 and/or at least that region of the shielding device 4 which has a thermally insulating action does not extend over the entire width 26 of the semifinished product 1.

[0030] The shielding device 4 can have a first shielding portion 10 with a first shielding means receiving unit (not illustrated) for receiving a first shielding means (not illustrated) and a second shielding portion with a second shielding means receiving unit for receiving a second shielding means, preferably the at least two shielding means are formed differently in terms of their material and/or material structure and/or arrangement and/or volume and/or weight and/or geometry. In this way, it is possible to provide a shielding device 4 which is loaded as required, depending on the region, with shielding means which differ in terms of their thermal insulation behavior. Consequently, a different action of heat on the semifinished product 1 by the heat source 3, 3′ can be achieved depending on the region, in particular both along a longitudinal extent and along a transverse extent of the semifinished product 1 to be heated. FIG. 3 illustrates the assembly position during the heating; here, the assembly illustrated with the semifinished product 1 is arranged in a heating region provided with a heating table 9, cf. FIG. 1.

[0031] The shielding device 4 can comprise at least one supporting means (not illustrated) which supports a shielding means, preferably the supporting means is arranged or formed in such a way that thermal expansion of at least one shielding means is reduced or prevented. The shielding device 4 can thus comprise elements which make it possible to reduce or prevent the thermal expansion of the shielding means.

[0032] The shielding device 4 can be formed or configured according to the exemplary embodiment illustrated in such a way that, during the heating of the semifinished product 1 by the heat sources 3, 3′, the semifinished product 1 is thermally shielded at least in certain portions on a top side 13 and at least in certain portions on a bottom side 14, preferably the shielding device 4 thermally shields the semifinished product 1 in a congruent and/or oppositely situated shielding region on its top and bottom side 13, 14. For this purpose, the shielding device can have a c-shaped form, for example. In particular, the two free limbs 15, 16 of the c-shape can be spaced apart by at most 15 mm, preferably by 10 mm, particularly preferably by 5.5 mm. The semifinished product 1 can be arranged at least in certain portions in the interior space 17 of the shielding device 4, which is c-shaped at least in certain portions, during the heating in the heating process. The sheet-like semifinished product 1 can be introduced or inserted into and guided out of or removed from the interior space 17 of the shielding device 4 through the region of the c-shaped shielding device 4 forming an opening 27.

[0033] The semifinished product 1 can be fed to a heating region in a manner arranged, in particular resting, on a product carrier 18, in particular a grid-like product carrier, wherein the semifinished product 1 is heated in the heating region, preferably the shielding device 4 can be fastened to the product carrier 18 via a fastening device 19 in particular releasably. The shielding device 4 can be fastenable in the manner of a grid pattern to at least two regions of the product carrier 18, in particular temporarily.

[0034] The product carrier 18 has supporting portions 20, 20′, 20″ for supporting a semifinished product 1 placed on the product carrier 18. The supporting portions 20, 20′, 20″ have a small contact surface, in particular punctiform or spot-like contact regions, with the semifinished product 1 to be deposited on the product carrier 18. The product carrier 18 can be provided with a holding device 28 in order for a manipulator (not illustrated) or a tool (not illustrated) to grip the product carrier 18 or to move such that the product carrier is displaced. For this purpose, the holding device 28 can be configured by way of example, as can be seen in FIG. 2, as an eyelet which is arranged in the grid structure, is preferably formed in one piece with the grid structure and in particular has a supporting function comparable to the supporting portions 20, 20′, 20″ for a semifinished product 1 which is to be placed on.

[0035] The at least one product carrier 18 can preferably comprise at least one shielding device receiving device 21, into which a shielding device 4 can be received at least temporarily, preferably the shielding device receiving device 21 is arranged or formed in such a way that thermal expansion of at least one shielding device 4 received in the shielding device receiving device 21 is reduced or prevented. The shielding device receiving device 21 can touch the shielding device 4 at least at two oppositely situated sides of the shielding device 4 and thus inhibit or reduce the expansion of the shielding device 4 at least in this direction. In the embodiment illustrated, the shielding device receiving device 21 is designed in the form of two elongate, sheet-like and grid-like receiving elements 22, 22′ which are fastened to the product carrier 18 in a form-fitting, materially bonded and/or force-fitting manner. The receiving elements 22, 22′ can preferably be fastened to one of at least two predefined fastening locations of the product carrier that are arranged in particular in the manner of a grid pattern. The shielding device 4 is inserted between these two receiving elements 22, 22′ preferably without play and is consequently blocked or impeded from expansion in at least one direction, illustrated here by way of example in the longitudinal direction 23 of the product carrier 18 illustrated. The receiving elements 22, 22′ likewise have a c-shape, wherein the semifinished product 1 is arranged temporarily in the inner region of the c-shaped receiving elements 22, 22′, cf. FIG. 3. The two receiving elements 22, 22′ are connected via preferably rod-shaped holding means 24, 24′, 24″. The holding means 24, 24′, 24″ can hold or fix the shielding device between the receiving elements 22, 22′ and/or block a relative movement of the two receiving elements 22, 22′ at least in one spatial direction. The at least one holding means 24, 24′, 24″ is preferably arranged or formed in such a way that the at least one shielding device 4 is blocked against thermal expansion at least in certain portions. By way of example, the holding means 24, 24′, 24″ is formed in a rigid and fixed manner in such a way that the shielding device 4 connected thereto in a materially bonded, form-fitting and/or materially bonded manner is blocked against thermal expansion thereof or prevented from thermally expanding. In this way, the situation is achieved in which a shielding device 4 remains constant in terms of its geometry and/or positional direction and/or alignment with respect to the semifinished product despite thermal stress during the heating. In particular, the holding means 24, 24′, 24″ can prevent or reduce a relative movement of the shielding device 4 with respect to the receiving elements 22, 22′ and/or with respect to the product carrier 18. It is thus possible, for example, to keep the gap dimension of the c-shaped opening 27 or the spacing of the two limbs 15, 16 of the c-shaped shielding device 4 constant or at least approximately constant. In the embodiment illustrated, the holding means 24, 24′, 24″ are formed as threaded rods provided with nuts at the end. The shielding device receiving device 21 can be in the form for example of at least one supporting template for a heat-absorber mass or heat-absorbing mass for the shielding means and/or for the shielding device 4.

[0036] The semifinished product 1 can have a thickness 25 or a sheet thickness of from 0.1 to 4.0 mm, preferably a thickness 25 of from 1.5 to 3.2 mm, particularly preferably a thickness 25 of from 2.2 to 2.6 mm. The semifinished product 1 can be formed at least in certain portions from metal, preferably the semifinished product 1 is formed at least in certain portions from steel, particularly preferably the semifinished product is formed at least in certain portions from a hot-forming steel.

LIST OF REFERENCE SIGNS

[0037] 1 Semifinished product [0038] 2, 2′ Input of heat [0039] 3, 3′ Heat source [0040] 4 Shielding device [0041] 5 First semifinished-product portion [0042] 6 Second semifinished-product portion [0043] 7 Length of 1 [0044] 8 Length of 9 [0045] 9 Heating table [0046] 10 First shielding portion [0047] 11 Second shielding portion [0048] 12 Third shielding portion [0049] 13 Top side of 1 [0050] 14 Bottom side of 1 [0051] 15 First limb [0052] 16 Second limb [0053] 17 Interior space [0054] 18 Product carrier [0055] 19 Fastening device [0056] 20, 20′, 20″ Supporting portion [0057] 21 Shielding device receiving device [0058] 22, 22′ Receiving element [0059] 23 Longitudinal direction [0060] 24, 24′, 24″ Connecting threaded rods [0061] 25 Thickness of 1 [0062] 26 Width of 1 [0063] 27 Opening in 4 [0064] 28 Holding device