EP2155917B1 - Process for producing a locally hardened profile component - Google Patents

Description

The present invention relates to a method for producing a profile component, which has a structurally increased strength, at least in sections, from a sheet metal semifinished product.

Profile members having high structural strength are used, for example, in the automotive industry for the manufacture of structural parts, such as side impact beams, bumpers or reinforcements for the A, B or C pillars of a motor vehicle. Since such profile components very high demands are made in terms of their strength, are used for their production frequently hoch-, higher and highest strength steels. For the profiling of the profile components different forming processes can be used. By way of example, at this point bending processes, in particular roll forming, should be mentioned.

The European patent EP 1 052 295 B1 discloses a process for the production of structural parts in the automotive industry, which at least partially have a high strength and a minimum ductility of 5% to 10%. In this method, the structural part by a soft state forming of boards, steel strip (in particular by roll profiling) or pipes configured and then brought by means of one of the structural part contour following, movable to the structural part, component encompassing inductor at least partially brought to the Austenitisierungstemperatur required for curing and then cooled with a the inductor in the direction of movement tracking cooling unit. The method known from the cited document is characterized primarily by the fact that the structural part is positioned substantially vertically and the inductor is displaced from top to bottom along the structural part, wherein the inductor and the cooling unit are relatively adjustable relative to each other and with a be displaced tool carriage connected.

In the method disclosed in the cited document, therefore, the starting material is first deformed in a still soft state into a profile component with a defined profile cross-section. In order to obtain the desired strength, the profile component is hardened in a subsequent process step by heating it to the austenitizing temperature and subsequently cooling it again. A defined cooling then causes the desired hardening of the profile component. A disadvantage of this known from the prior art method is that the starting material must always be brought into a soft state before it can be profiled and cured.
The DE 101 20 063 A1 and the WO 92/16665 A disclose processes for the production of profile components, in which the flat starting material (semi-finished sheet metal) is first brought by cold forming in its final contour. Only then does hardening take place (by heating and subsequent cooling) of at least partial areas of the profile component. The heating and cooling steps then at most a calibration step followed, but not the actual production the profile geometry is used. As a result, only possible geometrical deviations that have arisen due to the thermal process intervention are subsequently corrected. If in the WO 92/16665 A the talk is that after hardening further shaping operations follow, then this means no further Waizprofiiierschritte meant, but entirely alternative forming operations (for example, stationary bending or punching operations).

From the DE 101 20 063 A1 is another variant of a method for producing a profile component is known in which the starting material (sheet metal semi-finished product) is during molding at elevated temperature and therefore has a higher formability. However, it remains unclear how heat removal and thus unwanted hardening of the material in contact with the forming tools can be virtually avoided in this method.

In the DE 103 39 1 19 B3 discloses a method of making a profile member which provides for partial or complete cure by heating and subsequent cooling prior to actual molding. In each case, the hardened areas are transformed after hardening.

The present invention is based on the object to provide a method for producing a profile component available, which allows the production of profiled structures with defined zones of different, tailored to subsequent processing and / or application material and geometry properties.

With regard to the method, the object underlying the present invention is achieved by a method having the features of claim 1. The subclaims relate to advantageous and particularly expedient developments of the present invention.

In a method according to the invention for producing a profile component which has structurally increased strength at least in sections, a sheet metal semi-finished product is formed in an at least one-stage bending process and the bending process and subsequent separation and cutting operations of the sheet semifinished product are performed with a thermal treatment of at least one spatially limited area of the sheet semifinished product , which comprises at least one heating step and a subsequent cooling step, combined in such a way that the at least one spatially limited area after cooling has a structurally increased strength. The sheet metal semifinished product can be provided as a coil to the process described above, for example in strip form. With the aid of the method according to the invention, profile components can be produced with an open, with a partially open or also with a completely closed profile cross section. There is also the possibility that the profile components over the entire profile length at least partially different (changing) Have profile cross-sections, so that in principle profile components with arbitrarily complex configurations and cross-sectional shapes can be produced.

By a targeted removal of the introduced at least in a spatially limited area of the sheet metal semifinished heat can be achieved by a phase change during cooling advantageously in this area an increase in strength. In this case, as materials for the semi-finished sheet metal to prefer those which are at a sufficient Austenitisierung above a transition temperature (Austenitisierungstemperatur) A _r3 , during which the transformation of austenite to ferrite begins during cooling, are capable of sufficiently fast cooling rates a martensitic microstructure to develop. A martensitic microstructure is characterized by high strength. This advantageous behavior, for example, 22MnB5 tempered steels, from which the semi-finished sheet can consist.

The heat removal from the at least one preheated area can be carried out at least partially by direct contact of the sheet metal semifinished product with the bending tool, which can also be operated cooled if necessary. In addition, the use of liquid or gas-based cooling devices is possible in order to cool the semi-finished sheet media-based.

The particular advantage of the solution proposed here is that profile components can be produced with specifically adapted hardness properties. Thus, it is possible, for example, to produce a profile component which has sections hardened and partially uncured areas. The cured areas can be partially cured, fully cured or even partially hardened in sections and fully cured in sections.

In a preferred embodiment of the method, it is proposed that the sheet metal semi-finished product is bent stationary. For example, the stationary bending of the sheet semifinished product can be done by swaging.

In a particularly preferred embodiment, it is proposed that the bending of the sheet metal semifinished product in a roll forming device takes place by roll forming with a number of successive rolling steps. The sheet metal semi-finished product is continuously bent in the roll profiling in a plurality of successive profile rolling passes and thus brought into the desired profile shape. By roll forming, in particular, comparatively complex profile shapes and profile cross sections can also be produced. A superimposition of thermal and mechanical mechanisms can be achieved in profile production in a continuous roll forming process in a particularly advantageous manner. The gradual combination of local heat generation, shaping including any necessary cutting and separating operations and cooling can be precisely adjusted in their arrangement and microstructural design certain zones of increased strength.

A local spatial heating of the sheet metal semifinished product can be advantageously achieved by an inductive generation of an electromagnetic field or by a conductive current flow by means of the electrical resistance (or by a combination of these two methods) - ie by dissipation of electrical energy. There is in further advantageous embodiments, the possibility that the heat by one or more Laser light sources is introduced by an infrared radiation source or by means of a gas burner in defined areas of the sheet metal semi-finished product. Laser light sources have the advantage that the laser light generated by them can be focused, for example, by simple means on a comparatively small spatially limited area of the sheet metal semifinished product in order to bring about a local heating in this area to the desired temperature. The heating preferably does not take place exclusively by means of heating devices integrated on an inductive or else conductive basis in the process sequence (for example by inductors or conductive contact elements), but by means of electrical resistance heating in the form of contact with the shaping tools (rolling rollers) anyway for the purpose of transmitting the shaping force.

The cooling is advantageously carried out not only by direct heat removal by exposure to fluid coolants (preferably water) and / or gaseous coolants (preferably compressed air), but also by conduction through the contact of the sheet metal semi-finished with the forming forming tools (for example, with rollers of a roll forming ). The rolling rolls can be equipped for this purpose with an internal cooling, in which the heat dissipation via a cooling medium by appropriate introduced into the interior of the tool cooling channels in a circulating system. Thus, the heat dissipation in the sense of a targeted microstructure adjustment in a particularly advantageous manner is much more precisely controlled than it is even conceivable with a pure media cooling.

The cooling of the sheet metal semifinished product can in a particularly advantageous embodiment by heat conduction through the contact with the forming tools (rolling rollers) in combination with a direct cooling of the sheet semifinished product - for example by means of an (optionally supercooled) gas or with particulate ice (preferably dry ice) - take place. In this case, the gas or dry ice is blasted with a high pressure in the outlet of the roll stand on both sides of the sheet semifinished product surface (Walzgutoberfläche). In this case can be done by the irradiation into the nip in a particularly advantageous manner, a cooling of the rolling rolls simultaneously. The particulate ice advantageously removes additional surface contaminants and / or oxidation residues, scale or the like from the surface of the rolling stock (sheet metal semifinished product) and / or the surfaces of the rolls. Thus, the controllability of heat dissipation in terms of a targeted microstructure adjustment is significantly improved again. This can not be achieved by a pure quench cooling by means of fluid or gaseous cooling media, as used in the prior art.

It may be provided in a preferred embodiment that the heating of at least one portion of the sheet semifinished product takes place prior to bending. This embodiment is particularly preferred for stationary bending of the sheet metal semifinished product.

The production of a profile component with simultaneous exposure to heat can improve the processing properties during the molding in a particularly advantageous manner, since the deformation resistance can be reduced directly before each caused locally via the bending tools shape change or caused by special cutting tools material separation. An at least partially preheated sheet metal semi-finished has advantages in these areas a reduced resistance to the desired shape change during the bending process.

According to a further particularly advantageous embodiment, a plurality of regions of the sheet metal semifinished product to be heated are preheated successively, wherein each heating step is followed by a bending and cooling step.

According to a variant of the manufacturing method not according to the invention, the semi-finished sheet metal is first bent in several bending steps into the desired geometric shape of the profile component and then heated at least in sections. In this variant, the desired for subsequent processing and / or application of the profile component strength properties can be adjusted. In this embodiment, the heating of the profile component thus takes place only after completion of molding and also after the implementation of a possibly necessary Bauteilbeschnitts. The heat dissipation from the preheated areas of the sheet metal semifinished product can in this case via appropriate cooling media, which are connected downstream of the actual forming process.

During cooling, it may possibly lead to an undesirable distortion of the component. In the case of pronounced temperature gradients, moreover, due to locally different volume expansions in the workpiece, component failure due to crack formation can occur. Both effects can be suppressed in a particularly advantageous embodiment by the superposition of mechanical stresses in a calibration tool and by a corresponding heat dissipation via heat conduction. It may be appropriate, any necessary Profilbauteilbeschnitt perform in this variant of the method before the thermally induced curing.

With the aid of the method presented in the context of the present invention, the hardness properties of a profile component, which is produced by single or multi-stage bending of a sheet semifinished product, can be adapted specifically to different later uses of the profile component.

It has been shown that virtually every variant of the introduction of strength-enhanced regions into the profile component by targeted local introduction of heat during profiling leads to an improvement in the functional behavior of the profile component. Moreover, on the basis of this improved functional behavior, a weight reduction can be achieved by a reduced sheet thickness in comparison with a thermally unaffected component without sacrificing performance

An advantage of the method presented here is that the deformation of previously thermally treated, hardened areas of the sheet semifinished product is avoided due to their low formability, the resulting failure risk and beyond also due to the expected high forming forces. In other words, only such areas of the flat starting material are subjected to a partial thermal treatment by heating and cooling, which are not subject to direct forming during the subsequent roll forming.

In the present case, the partial heating of the sheet metal semifinished product is not solely the initiation of a heat treatment with the aim of setting a defined structure state, but also to to increase the forming capacity of the base material of which the sheet metal semifinished product, to the extent that the process forces available in each individual forming step, a defect-free deformation to the desired extent is achieved. This increase is based on the one hand on the higher processing temperature per se, on the other hand on simultaneously running thermally induced Entfestigungsvorgängen. This can and should be done not only before the entry of the starting material in the sequence of Walzprofilierschritten, but preferably also between the individual molding steps during roll forming.

• Positionierung der lokalen Wärmebehandlung nach der Notwendigkeit einer gleichzeitigen Erhöhung des lokalen Umformvermögens.
• Positionierung der lokalen Wärmebehandlung immer dann, wenn die in den vorhergehenden Kaltumformschritten erfolgte Kaltverfestigung zu einem für die weitere Umformung nicht hinreichenden Restumformvermögen geführt hat, das durch eine thermisch induzierte Entfestigung im für die nachfolgende Umformung notwendigen Umfang wieder erhöht werden kann,
• Positionierung der lokalen Wärmebehandlung immer dann, wenn die betreffenden Geometriebereiche des Blechhalbzeugs keiner nennenswerten Umformung in der weiteren Prozessfolge ausgesetzt sind.

In the method presented here, there is the possibility that the heat treatment of the sheet metal semi-finished does not take place before the actual profile production by roll forming or after profiling, but rather takes place selectively in several intermediate steps. The positioning of these heat treatment intermediate steps takes place according to clear methodical principles:

• Positioning of the local heat treatment after the need to simultaneously increase the local forming capacity.
• Positioning of the local heat treatment whenever the work hardening carried out in the preceding cold forming steps has led to a residual workability which is insufficient for the further forming and which can be increased again by a thermally induced softening in the amount necessary for the subsequent forming,
• Positioning of the local heat treatment whenever the relevant geometry ranges of the sheet metal semifinished product are not subjected to significant deformation in the further process sequence.

The profile component may be produced by a method according to one of claims 1 to 14 and at least one partially cured area and / or at least one through-hardened area and / or at least one area which is partially cured and partially cured in sections. There is also the possibility that the profile component over its profile length at least partially having different profile cross-sections. Furthermore, in one embodiment, the profiled component can have different (changing) strength properties at least in sections over its profile length.

In one use, at least one profile member is used to make a component that is suitable for guiding and absorbing power of moving components and devices of a vehicle. Especially with such components, the use of the produced according to the method described above, at least partially cured profile components is particularly advantageous.

For example, from such a profile component, a guide rail for a safety belt with an increased deformation resistance can be produced, so that in particular Advantageously, a detachment of a substantially slid-shaped Gurtbefestigung from the guide rail can be effectively prevented.

The profile component can also be used in an advantageous embodiment, a guide rail for a safety belt with an increased resistance to contact-bound wear when adjusting the carriage-shaped Gurtbestigung be prepared.

Another preferred example of use of the profile component forms the production of seat mounting rails with an increased deformation resistance, so that a detachment of the vehicle seat from its vehicle-mounted attachment can be advantageously prevented.

For example, seat mounting rails with increased resistance to contact-related wear when adjusting the seating position can also be produced from the profile component.

Another advantageous example of using the profile member is to fabricate a sidewall guide rail for a sidewall sliding door of a motor vehicle, the sidewall guide rail having increased resistance to contact wear when opening and closing the door.

Furthermore, from the profile component, a side wall guide rail for a sliding door can be produced which has an increased resistance to deformation compared with the solutions known from the prior art, in order to be able to do so To prevent structural failure and the detachment of the sidewall sliding door in the event of an accident.

In another use, at least one profile member is used to make a structural member that has increased resistance to intrusion and is capable of receiving and degrading applied energy via a material or component deformation. Even with such components, the use of the at least partially hardened profile components produced by the method described above is particularly advantageous, which allows the strength properties of the profile components to be adjusted gradually.

For example, from the profile component part of a cross-member for a cockpit of a motor vehicle with an increased deformation resistance can be produced, so that a structural failure in the event of an accident by the action of force on the steering column can be effectively avoided.

Another exemplary use of a profile component provides the production of a part of a module cross member for a cockpit with an increased deformation resistance in order to prevent a structural failure in an accident by the force of an airbag module in a particularly advantageous manner.

The module cross member may in particular be an instrument panel carrier.

A further advantageous use of the profiled construction consists in the production of a module cross member (in particular a dashboard support) with an optimized Natural frequency behavior to avoid unwanted vibrations and thus improve the acoustics in the interior of the vehicle.

In a further advantageous embodiment, for example, a carrier (longitudinal or transverse carrier) with an increased deformation resistance can also be produced from a profile component in order to cause structural failure in the region of the A, B and C pillars of the motor vehicle in the event of a front or side impact to prevent.

Furthermore, the profile component can also be used, for example, for producing a bumper support with an increased deformation resistance in order to advantageously prevent structural failure in the area of the crash boxes of the motor vehicle.

According to a further advantageous use, side impact beams with an increased deformation resistance can be produced from the profile component. Such side impact beams are integrated into the body in order to increase the body rigidity and thereby improve the protection and the stability of the passenger compartment, in particular in the event of a side impact. By using a partially hardened profile component, a structural failure in the connection region to the door structure and thus in the mainly crash-loaded area can be prevented in an advantageous manner.

Fig. 1

schematisch die thermischen und mechanischen Prozessabläufe bei der Herstellung eines Profilbauteils aus einem Blechhalbzeug gemäß einem ersten Ausführungsbeispiel eines nicht zur Erfindung gehörenden Verfahrens;

Fig. 2

schematisch die thermischen und mechanischen Prozessabläufe bei der Herstellung eines Profilbauteils aus einem Blechhalbzeug gemäß einem zweiten Ausführungsbeispiel eines Verfahrens der vorliegenden Erfindung;

Fig. 3

schematisch die thermischen und mechanischen Prozessabläufe bei der Herstellung eines Profilbauteils aus einem Blechhalbzeug gemäß einem dritten Ausführungsbeispiel eines nicht zur Erfindung gehörenden Verfahrens;

Fig. 4a

ein erstes Ausführungsbeispiel eines Profilbauteils, das mittels des hier vorgestellten Verfahrens hergestellt worden ist und mehrere Zonen mit definiert erhöhter Festigkeit aufweist;

Fig. 4b

eine perspektivische Darstellung des Profilbauteils gemäß Fig. 4a;

Fig. 5a

ein erstes Ausführungsbeispiel eines Profilbauteils, das mittels des hier vorgestellten Verfahrens hergestellt worden ist und mehrere Zonen mit definiert erhöhter Festigkeit aufweist;

Fig. 5b

eine perspektivische Darstellung des Profilbauteils gemäß Fig. 5a;

Fig. 6

ein Härteprofil über die Abwicklung der Bauteilkontur des Profilbauteils gemäß Fig. 4a und 4b;

Fig. 7

ein Härteprofil über die Abwicklung der Bauteilkontur des Profilbauteils gemäß Fig. 5a und 5b;

Fig. 8

die Kraft-Weg-Vertäufe der in Fig. 4a, 4b und 5a, 5b dargestellten Profilbauteile bei einer Zugbeanspruchung;

Fig. 9

die Kraft-Weg-Verläufe der in Fig. 4a, 4b und 5a, 5b dargestellten Profilbauteile bei einem Dreipunkt-Biegeversuch;

Fig. 10

eine perspektivische Darstellung einer Führungsschiene für eine Tür, einen Sitz oder dergleichen eines Kraftfahrzeugs;

Fig. 11

eine Darstellung des Profilquerschnitts der Führungsschiene gemäß Fig. 10;

Fig. 12

eine perspektivische Darstellung eines Grundprofils eines Instrumententafelträgers mit einem geschlossenen Profilquerschnitt;

Fig. 13

eine Darstellung des Profilquerschnitts eines Profilbauteils des Instrumententafelträgers gemäß Fig. 12;

Fig. 14

eine perspektivische Ansicht eines Trägerbauteils eines Kraftfahrzeugs;

Fig. 15a

eine schematische Darstellung eines ersten Aufheizmusters zum Aufheizen des Blechhalbzeugs;

Fig. 15b

eine schematische Darstellung eines zweiten Aufheizmusters zum Aufheizen des Blechhalbzeugs;

Fig. 15b

eine schematische Darstellung eines dritten Aufheizmusters zum Aufheizen des Blechhalbzeugs.

Further features and advantages of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings. Show in it

Fig. 1

schematically the thermal and mechanical processes in the production of a profile component from a sheet metal semi-finished product according to a first embodiment of a method not belonging to the invention;

Fig. 2

schematically the thermal and mechanical processes in the manufacture of a profile component from a sheet metal semi-finished product according to a second embodiment of a method of the present invention;

Fig. 3

schematically the thermal and mechanical processes in the manufacture of a profile component from a sheet metal semi-finished product according to a third embodiment of a method not belonging to the invention;

Fig. 4a

a first embodiment of a profile component, which has been produced by means of the method presented here and having a plurality of zones with defined increased strength;

Fig. 4b

a perspective view of the profile component according to Fig. 4a ;

Fig. 5a

a first embodiment of a profile component, which has been produced by means of the method presented here and having a plurality of zones with defined increased strength;

Fig. 5b

a perspective view of the profile component according to Fig. 5a ;

Fig. 6

a hardness profile on the settlement of the component contour of the profile component according to Fig. 4a and 4b ;

Fig. 7

a hardness profile on the settlement of the component contour of the profile component according to Fig. 5a and 5b ;

Fig. 8

the force-way sales of in Fig. 4a . 4b and 5a . 5b shown profile components in a tensile stress;

Fig. 9

the force-displacement curves of in Fig. 4a . 4b and 5a . 5b shown profile components in a three-point bending test;

Fig. 10

a perspective view of a guide rail for a door, a seat or the like of a motor vehicle;

Fig. 11

a representation of the profile cross-section of the guide rail according to Fig. 10 ;

Fig. 12

a perspective view of a basic profile of a dashboard support with a closed profile cross-section;

Fig. 13

a representation of the profile cross section of a profile component of the instrument panel carrier according to Fig. 12 ;

Fig. 14

a perspective view of a support member of a motor vehicle;

Fig. 15a

a schematic representation of a first Aufheizmusters for heating the sheet metal semi-finished product;

Fig. 15b

a schematic representation of a second Aufheizmusters for heating the sheet metal semi-finished product;

Fig. 15b

a schematic representation of a third heating pattern for heating the sheet metal semi-finished product.

With reference to Fig. 1 to 3 three different advantageous embodiments of a method for producing a profile component 1 from a preferably band-like sheet metal semi-finished product 2 will be explained in more detail below. In Fig. 1 to 3 For this purpose, the thermomechanical processes in a combined heating and shaping of the sheet semifinished product 2 for the production of the profile component 1 in a particularly preferred according to the present invention Walzprofilierverfahren which is carried out in a roll forming, shown schematically.

The three preferred embodiments shown here differ in particular by different process sequences in the at least partially heating of the sheet semifinished product 2 before, during or after the forming. Shown in each case is the time-dependent course of the temperature, which prevails in defined (spatially limited) areas A, B, C, D of the sheet semifinished product 2 before, during and after the individual forming steps. Around In addition to the temperature profile, the geometric shape of the sheet metal semifinished product 2 to produce a desired profile cross section to illustrate, in the upper part of the figures, respectively, the shaping of the sheet metal blank 2 is shown in the corresponding rolling step in the roll forming.

1. 1. A_r3 die Umwandlungstemperatur, bei der - während der Abkühlung - die Umwandlung von Austenit zu Ferrit beginnt. Bei Bor-Mangan-legierten Vergütungsstählen, wie zum Beispiel 22MnB5, liegt die Umwandlungstemperatur A_r3 typischerweise bei 850°C ± 100°C;
2. 2. A_r1 die Umwandlungstemperatur, bei der - während der Abkühlung - die Umwandlung von Austenit zu Ferrit beendet ist Bei Bor-Mangan-Iegierten Vergütungsstählen, wie zum Beispiel 22MnB5, liegt die Umwandlungstemperatur A_r1 typischerweise bei 650°C ± 100°C;
3. 3. M_s die Umwandlungstemperatur, bei der - während einer raschen Abkühlung - die Umwandlung von Austenit zu Martensit schlagartig erfolgt. Bei Bor-Mangan-Iegierten Vergütungsstählen, wie zum Beispiel 22MnB5, liegt diese Umwandlungstemperatur typischerweise bei ca. 400 °C ± 100 °C.
4. 4. α: Ferrit (bei schneller Abkühlung auf eine Temperatur unterhalb von M_s bildet sich eine Gefügevariante aus, die als Martensit bezeichnet wird und sich durch ein gehärtetes Gefüge mit hoher Festigkeit auszeichnet);
5. 5. α+γ: Ferrit und Austenit liegen gleichzeitig vor. Je weiter die Temperatur unter die Umwandlungstemperatur A_r3 absinkt desto größer ist der Anteil an Ferrit und desto geringer ist der Anteil an Austenit.
6. 6. y: Austenit

In Fig. 1 to 3 also designate:

1. 1. A _{r3 is} the transformation temperature at which - during the cooling - the transformation of austenite to ferrite begins. For boron-manganese alloy tempered steels, such as 22MnB5, the transition temperature A _{r3 is} typically 850 ° C ± 100 ° C;
2. 2. A _{r1 is} the transformation temperature at which the austenite to ferrite transformation is completed during cooling. For boron-manganese alloyed temper steels, such as 22MnB5, the transition temperature A _{r1 is} typically 650 ° C ± 100 ° C;
3. 3. M _{s is} the transformation temperature at which - during a rapid cooling - the transformation from austenite to martensite occurs abruptly. For boron-manganese alloyed temper steels, such as 22MnB5, this transition temperature is typically around 400 ° C ± 100 ° C.
4. 4. α: ferrite (when cooled rapidly to a temperature below M _s , a microstructural variant is formed, which is referred to as martensite and is characterized by a hardened structure with high strength);
5. 5. α + γ: ferrite and austenite are present at the same time. The further the temperature falls below the transformation temperature A _r3, the greater the proportion of ferrite and the lower the proportion of austenite.
6. 6. y: austenite

The bending of the sheet metal semifinished product 2, which may consist of a hardenable steel - for example of 22MnB5 - and optionally may also be at least partially coated, for forming a profile component 1 with defined geometric properties takes place in the in Fig. 1 to 3 shown process variants in a roll forming process with a number n consecutive rolling steps, in each of which a rolling pass is performed. Although in Fig. 1 to 3 only profile components 1 with an open. Profile cross-section are shown, it should be noted at this point that with the method presented here differently shaped profile components 1 of different complexity can be made with an open, with a partially open or even with a completely closed profile cross-section. There is also the possibility that the profile components 1 over their entire profile length at least partially different (ie changing) profile cross-sections, so that in principle profile components 1 with an arbitrarily complex profile shape and mif an arbitrarily complex profile cross section can be produced.

At the in Fig. 1 schematically illustrated first, non-inventive embodiment of the method for producing a profile component 1 is carried out a heating of the sheet metal semi-finished product 2 in defined, spatially limited areas A, C and D already immediately before the first, designated 1st roll pass in Walzprofiliervorrichtung. As in Fig. 1 can be seen, the sheet metal blank 2 is heated locally before the first rolling pass in a central region A and two outer regions C and D to a temperature T which is greater than the transformation temperature A _r3 , during which - during the cooling - the conversion from austenite to ferrite begins. The remaining areas B of the sheet semifinished product 2 are not heated in contrast to the profiling and thus not specifically influenced thermally.

Preferably, the sheet semifinished product 2 is in the defined areas A, C and D by an inductive generation of an electromagnetic field or by a conductive current flow by means of the electrical resistance or alternatively by a combination of these two methods - and therefore by dissipation of electrical energy - locally controlled on the Temperature T> A _r3 heated. Alternatively, other methods and corresponding devices for heat input into the localized areas A, C and D of the sheet semifinished product 2 can be used. For example, the controlled heat input by applying the sheet semifinished product 2 with laser light, which is generated by at least one laser light source, or with infrared radiation, which is generated by at least one infrared radiation source, or by the use of a gas burner.

As in Fig. 1 can be seen, the sheet metal blank 2 is formed in a first rolling pass with decreasing temperature after the maximum temperature has been reached in the areas A, C and D. The first rolling pass takes place at a temperature which is still above the transformation temperature A _r3 . The for setting a desired microstructure in the locally preheated areas A, C and D of the sheet semifinished product 2 from this during the cooling necessary heat dissipation can be done in the first pass of Walzprofilierprozesses, for example by conduction of heat in contact with the rolls of the roll forming. If necessary, the rolls of the roll forming device can also be operated cooled. Alternatively or additionally, the heat dissipation from the preheated areas A, C and D of the sheet semifinished product 2 can also be effected by a media-based cooling, in which the sheet semifinished product is subjected to a liquid or gaseous coolant.

It can also be seen that the rolling passes 2... N subsequent to the first rolling pass, which are required for further shaping of the sheet semifinished product 2 to produce the final geometry of the profile component 1, take place in this exemplary embodiment at temperatures which are always below the transformation temperature A _r1 in which the austenite to ferrite transformation is completed during the cooling: The last (nth) rolling pass required for configuring the profile component 1 takes place in this embodiment at a temperature which is less than the transformation temperature M _s is that during a rapid cooling abruptly the conversion of austenite to martensite occurs. Alternatively, however, the final rolling pass may also be carried out at a temperature which is greater than the transformation temperature M _s .

In addition to the nth rolling pass, which ends the actual shaping of the profile component 1, in this exemplary embodiment, a so-called calibration pass, which is carried out by means of a suitable calibration tool, also follows. The change in the geometry of the profile component 1, which possibly occurs due to the formation of thermally induced residual stresses, can occur advantageously be compensated in a final rolling pass, the calibration pass, immediately after the simultaneous heat dissipation from the workpiece. In a process step following the calibration pass, the profile component 1 is brought to the desired length by means of a separating and cutting device.

The method variant described here is particularly advantageous when, as a result of the heat influence in the defined areas A, C and D of the sheet metal semifinished product 2, a significant increase in strength has come about due to a so-called transformation hardening. The locally defined regions A, C and D then have a drastically increased resistance to a further change in shape in a subsequent rolling step. This therefore means that preferably only those regions of the sheet metal semifinished product 2 should undergo such a heat treatment, which are no longer subject to any noticeable change in shape in the further process sequence. A transformation of previously hardened areas A, C and D of the sheet semifinished product 2 is due to their low formability, the resulting failure risk and beyond also due to the expected high forming forces thus not.

With reference to Fig. 2 a second embodiment of a method for producing a profile component 1 from a sheet metal semi-finished product 2 is explained in more detail below. In this variant of the method, a heating of the sheet metal semifinished product 2 takes place in the defined areas A, C and D successively during roll profiling, in each case between the individual rolling steps. As in Fig. 2 1, a first (middle) region A of the sheet metal semifinished product 2 is locally heated to a temperature T which is greater than the transformation temperature A _r3 (austenitizing temperature) prior to the first rolling pass.

In contrast, the other areas of the sheet semifinished product 2 are initially not targeted thermal influence.

Following the defined preheating of the first region A, the first rolling pass is performed in the roll forming device. Subsequently, the area A of the sheet metal semifinished product 2 is again cooled to a temperature which is lower than the transformation temperature M _s . The cooling can in turn be effected by heat conduction in a contact of the sheet metal semifinished product 2 with the optionally cooled rolls of the rolling device and / or media-based by acting on the sheet semifinished product 2, in particular the locally preheated area, with a liquid or gaseous coolant.

In a next heating step, a second (near-edge) region C of the sheet semifinished product 2 is locally heated to a temperature T which is greater than the transformation temperature A _r3 . The remaining areas, in particular the areas A and B of the sheet metal semifinished product 2, in contrast, are not specifically heated in this method step. Subsequently, a second roll pass is performed to further profile the sheet semifinished product 2. As in Fig. 2 can be seen, the preheated area C of the sheet semifinished product 2 is cooled again after the rolling pass to a temperature which is lower than the transformation temperature M _s .

In a corresponding manner, in a further heating step, which may optionally have been preceded by further rolling passes in which no local heating of the sheet semifinished product 2 is carried out, another (near-edge) region D is locally heated to a temperature T, which in turn is greater than the transformation temperature A. _r3 is. The other areas, in particular the areas A, B and C of the sheet metal semifinished product 2 are in contrast not specifically heated locally. Subsequently, a further rolling pass is performed in order to further profile the sheet semifinished product 2. As in Fig. 2 to recognize the area C of the sheet semifinished product 2 is cooled after this rolling pass again to a temperature which is lower than the transformation temperature M _s . If necessary, further rolling passes can be followed by this rolling pass, which can be carried out with or without preheating of locally defined regions of the sheet semifinished product 2. The targeted heating of the areas A, C and D of the sheet semifinished product 2 can also be done in this embodiment by means of the above-described methods or devices.

In a final rolling pass, which terminates the profiling of the sheet metal semifinished product 2 to form a profile component 1, a calibration stitch in a calibration device can also be connected in this embodiment before the profile component 1 is then cut to its desired length by means of a separating and cutting device.

• Positionierung der lokalen Wärmebehandlung nach der Notwendigkeit einer gleichzeitigen Erhöhung des lokalen Umformvermögens,
• Positionierung der lokalen Wärmebehandlung immer dann, wenn die in den vorhergehenden Kaltumformschritten erfolgte Kaltverfestigung zu einem für die weitere Umformung nicht hinreichenden Restumformvermögen geführt hat, das durch eine thermisch induzierte Entfestigung im für die nachfolgende Umformung notwendigen Umfang wieder erhöht werden kann,
• Positionierung der lokalen Wärmebehandlung immer dann, wenn die betreffenden Geometriebereiche des Blechhalbzeugs 2 keiner nennenswerten Umformung in der weiteren Prozessfolge ausgesetzt sind.

The heat treatment of the sheet semifinished product 2 does not take place here before the start of the actual profile production by roll forming or after profiling, but rather takes place selectively in several intermediate steps. The positioning of these heat treatment intermediate steps takes place according to clear methodical principles:

• Positioning of the local heat treatment after the need to simultaneously increase the local forming capacity,
• Positioning of the local heat treatment whenever it occurred in the previous cold forming steps Work hardening has led to a residual forming capacity which is insufficient for the further forming and which can be increased again by a thermally induced softening in the amount necessary for the subsequent forming,
• Positioning of the local heat treatment whenever the relevant geometry ranges of the sheet metal semifinished product 2 are not subjected to any appreciable deformation in the further process sequence.

In the Fig. 2 shown method variant is particularly advantageous if it is on the one hand targeted to reduce the resistance to a desired in the immediate subsequent rolling step change in the geometric shape of the sheet metal blank 2, and if it is desirable on the other hand, these areas after the previous in the previous rolling passes already made local to adjust geometrical shape in their microstructure. Insofar as the targeted modification of the microstructure also increases the strength while simultaneously increasing the deformation resistance, it is also advantageous in this exemplary embodiment that only those regions of the sheet metal semifinished product 2 preferably undergo a targeted heat treatment, which in the further process sequence no longer (noticeable) changes in shape subject. In other words, only those areas of the flat sheet semifinished product 2 are subjected to a partial thermal treatment by heating and cooling, which are not subjected to direct forming during the subsequent roll forming steps.

Fig. 3 shows a third not belonging to the invention embodiment of a method for producing a profile component 1 from a sheet metal semi-finished product 2. In contrast to the two described above Embodiments takes place in this variant of the method, the heating in the locally defined areas A, C and D of the sheet semifinished product 2 only after completion of the generation of the final geometry of the profile component 1 in a previous sequence of n rolling passes in the roll forming. The profiling of the Blechhaibzeugs 2 thus takes place at an ambient temperature which is substantially lower than the transformation temperature M _s . It becomes clear that the defined areas A (central) and C and D (near the edge) of the sheet metal semifinished product 2 are simultaneously heated to a temperature T which is greater than the transformation temperature A _r3 after the forming.

The local heating of the regions A, C and D after the final shaping of the sheet-metal semifinished product 2 to form a profile component 1 serves in this embodiment exclusively for the purpose of a thermally induced increase in the strength of the profile component 1 by a transformation hardening. The change in the geometry of the profile component 1 which may occur as a result of the formation of thermally induced residual stresses can advantageously be compensated for in a final rolling pass, the so-called calibration pass, immediately after the heat removal taking place here simultaneously. The locally deliberately heated areas A, C, and D are thus cooled again, so that in the calibration tool the calibration engraving can be carried out at a temperature which is slightly higher than the transformation temperature M _s .

The targeted local heating and subsequent cooling of the spatially limited areas A, C and D of the sheet metal semifinished product 2 can be carried out in the manner described above with reference to Fig. 1 and 2 detailed.

Preferably, in the process variants described here, the targeted local heating of the sheet semifinished product 2 does not take place exclusively by means of heating means integrated in the process sequence on an inductive or else conductive basis (for example by inductors or conductive contact elements), but by means of electrical resistance heating in any case for the purpose of transmitting the shaping force ongoing contact with the forming tools (rolling rollers).

The cooling of the sheet semifinished product 2 is advantageously carried out in all the process variants presented here not exclusively via direct heat removal by exposure to fluid coolants (preferably water) and / or gaseous coolants (preferably compressed air), but also by heat conduction via the contact of the sheet metal semifinished product 2 with the shaping Forming tools (here: rolling rolls). The rolling rolls can be equipped for this purpose with an internal cooling, in which the heat dissipation via a cooling medium via appropriately introduced in the interior of the tool cooling channels in a circulating system. Thus, the heat dissipation in terms of a targeted microstructure adjustment in a particularly advantageous manner is much more precisely controlled, as it is even conceivable with a pure media cooling. The cooling of the sheet semifinished product 2, for example, by heat conduction via the contact with the forming tools (rolling rollers) in combination with a direct cooling of the sheet semifinished product 2 - for example by means of an optionally supercooled gas or with particularized ice (preferably dry ice) - done. In this case, the gas or dry ice is blasted with a high pressure in the outlet of the roll stand on both sides of the sheet semifinished product surface (Walzgutoberfläche). It can by the irradiation into the roll gap in a particularly advantageous manner, a cooling of the rolling rolls done simultaneously. The particulate ice advantageously removes additional surface contaminants and / or oxidation residues, scale or the like from the surface of the rolling stock and / or the surfaces of the rolls. Thus, the controllability of heat dissipation in terms of a targeted microstructure adjustment is significantly improved again. This is not attainable at all by a pure quench cooling by means of fluid or gaseous cooling media, as used in the prior art.

In Fig. 4a and 4b a first embodiment of a profile component 1 is shown, which can be produced by means of one of the methods presented here. The profile component 1 has an open profile cross-section and has three regions 10, 11, 12 which, compared to the other regions, have a structurally increased strength induced by local heating and subsequent cooling. A first region 10 with a structurally increased strength is formed in the profile sole of the profile component 1. The two remaining regions 11, 12 with structurally increased strength are formed at the inwardly directed ends of the profile flanks. Such a profile component 1 with three defined, spatially limited areas 10, 11, 12, which have a structurally increased strength can be used for example for producing a guide rail for a safety belt with an increased deformation resistance, so that a detachment of a substantially slid-shaped Gurtbefestigung can be effectively prevented from the guide rail.

The profile component 1 can also be used to a guide rail for a safety belt with a raised Resistance to contact wear when adjusting the carriage-shaped Gurtbefestigung produce.

Fig. 5a and 5b show a second embodiment of a profile component 1, which has been produced by means of one of the methods presented here, and which also for producing a guide rail for a safety belt with the above with reference to Fig. 4a and 4b described properties can be used. The profile component 1 has an open profile cross-section and has three regions 10, 11, 12 which, compared to the other regions, have a structurally increased strength induced by local heating and subsequent controlled cooling. A first region 10 with a structurally increased strength is again formed in the profile sole of the profile component 1. The two remaining regions 11, 12 with structurally increased strength are formed approximately in the middle of the profile flanks oriented substantially perpendicular to the profile sole.

With reference to Fig. 6 and 7 the resulting strength profiles of in Fig. 4a to 5b shown profile components 1, which consist of the material 22MnB5 will be explained in more detail. The hardness measured in accordance with DIN EN ISO 6507-1 (Vickers hardness HV1) is plotted over the distance from the outer edge of the contour development a. The maximum local heating temperature in the production of profile components 1 was 900 ° C.

The results show that the strength in the locally heated and hardened regions 10, 11, 12 during manufacture is significantly higher than in the remaining, non-heat treated regions of the profile component 1. While in the non-cured regions, HV1 values are on the order of about 200 to 300 could be measured, these values were more than 500 in the hardened areas and could reach a value of nearly 600 in some sections.
In Fig. 8 the results of static tensile tests, which were performed on three different profile components 1, 1 'graphically summarized. In these tests, an application-oriented loading direction of the profile components 1, 1 'was selected. Shown are the force-displacement curves in a tensile stress. With I, the results for the in Fig. 4a and 4b shown profile component 1 and II are the results for in Fig. 5a and 5b shown profile component 1 shown. III additionally designates the force-displacement profile of a fully hardened profile component 1 '. A comparison of the measurement results shows that the two only partially cured profile components 1, which have been produced by one of the methods described herein, a lower tensile strength and a higher elongation at break than the fully cured profile component 1 '.

In Fig. 9 finally, the results of a three-point bending test, which was carried out on the profile components 1, 1 'produced by means of one of the methods presented here, are shown. In the standardized examination of the profile components 1, 1 'in the three-point bending test also shows a significant increase in the load capacity, which proves to be the most favorable in the present case of claim for the fully cured profile component 1'.

With reference to 10 to 14 Below are some examples of the use of the profile components 1, 1 'produced by the method explained in more detail above, which at least partially have a structurally increased strength, will be explained in more detail.

In 10 and 11 a guide rail 30 is shown, which is suitable for example for a door, a seat or a belt of a motor vehicle. The guide rail 30 was produced by using a partially hardened profile component 1. As in particular in Fig. 11 1, the profile component 1 from which the guide rail 30 has been produced has, in this exemplary embodiment, a first and a second partially hardened region 10, 10 ', which are arranged opposite one another, and a completely hardened region 11. In particular, the at least partially hardened regions 10, 10 ', 11 enhance the resistance to deformation from dislodging a substantially slid-shaped strap attachment from the guide rail 30, and also provide increased resistance to contact wear when adjusting the strap attachment. It should be noted at this point that the positions of the at least partially hardened regions 10, 10 ', 11 of the profile component 1 are only examples and in the production of the profile component 1 by means of one of the methods presented here specifically to the subsequent use of the guide rail 30th can be adjusted.

Another example of use for the profile components 1, 1 'presented here is in FIG FIGS. 12 and 13 shown. This is a basic profile 31 of an instrument panel support, which in this example is made of two closed and interconnected profile components 1, 1 'with different profile cross sections.

The first profile component 1 has approximately in its center a flattened region 10, which is partially hardened and is provided for a connection of the steering column of the motor vehicle. The second profile component 1 'has in this embodiment, a through-hardened area 11, which is provided for the airbag area. The basic profile of the instrument panel support 31 can also be produced in other advantageous embodiments by using a single profile component 1, 1 'or by using more than two profile components 1, 1'. A further advantageous use of the profile components 1, 1 'consists in the production of a module cross member - in particular a (part of) an instrument panel carrier - with an optimized natural frequency behavior to avoid unwanted vibrations and thus to improve the acoustics in the interior of the vehicle

Fig. 14 finally shows a trained as an open structure profile side rail 32 of a motor vehicle. The longitudinal member 32 has been produced from a profile component 1, which has a first partially hardened region 10, a second through-hardened region 11 and a third region 12, which is through-hardened in sections and partly hardened in sections. The longitudinal member 32 further has three mounting portions 320, 321, 322, which may be part of the profile component 1 (but need not be mandatory), for connecting the longitudinal member 32 to the A-pillar, B-pillar or C-pillar of a vehicle. Incidentally, in this embodiment, the first mounting portion 320 for the A pillar, the second mounting portion 321 for the B pillar, and the third mounting portion for the C pillar are provided.

In Fig. 15a to 15c Finally, three different patterns 40, 41, 42 of a heating zone are shown, in which the sheet semifinished product 2 can be heated at least in sections. In principle, various, freely selectable courses and forms of the heating zone pattern are conceivable.

Claims (14)

1. Process for producing a profile component (1), which has at least in portions a structurally increased strength, from a sheet metal semifinished product (2), the sheet metal semifinished product (2) being formed in a multiple-stage bending process, and the bending process and also subsequent operations for separating and cutting the sheet metal semifinished product (2) are combined with a thermal treatment of a plurality of spatially delimited regions (A, C, D) of the sheet metal semifinished product (2), which comprises a plurality of heating steps and a plurality of cooling steps following these, in such a way that, after cooling, the spatially delimited regions (A, C, D) have a structurally increased strength, a first spatially delimited region (A) of the sheet metal semifinished product (2) initially being heated to a temperature which is higher than the austenitizing temperature A_r3 of the sheet metal semifinished product (2) at which, during cooling, the transformation from austenite to ferrite commences, before the sheet metal semifinished product (2) is bent, and, after the first forming step, at least one further spatially delimited region (C, D) of the sheet metal semifinished product (2) being heated to a temperature which is higher than the austenitizing temperature A_r3 of the sheet metal semifinished product (2), before the sheet metal semifinished product (2) is bent further.
2. Process according to Claim 1, characterized in that the sheet metal semifinished product (2) is bent in a stationary bending process, in particular by die-bending.
3. Process according to Claim 1, characterized in that the bending of the sheet metal semifinished product (2) takes place in a roll-profiling device by means of roll-profiling with a number of successive rolling steps, the rolls of the roll-profiling device preferably being operated, cooled.
4. Process according to one of Claims 1 to 3, characterized in that the sheet metal semifinished product (2) is heated by an inductive generation of an electromagnetic field or by a conductive current throughflow by means of the electrical resistance or by a combination of these two heating processes in the spatially delimited regions (A, C, D).
5. Process according to one of Claims 1 to 4, characterized in that the sheet metal semifinished product (2) is heated by means of at least one laser light source and/or at least one infrared light radiation source and/or at least one gas burner in the spatially delimited regions (A, C, D).
6. Process according to one of Claims 1 to 5, characterized in that a heating pattern is generated on the sheet metal semifinished product (2).
7. Process according to one of Claims 1 to 6, characterized in that, after a heating and/or bending step, the sheet metal semifinished product (2) is cooled by means of a liquid-based or gas-based cooling device.
8. Process according to one of Claims 1 to 7, characterized in that the cooling of the sheet metal semifinished product (2) takes place by heat conduction via contact with the shaping tools, in combination with a direct cooling of the sheet metal semifinished product (2), in particular by means of a gas or by means of particularized ice.
9. Process according to one of Claims 3 to 8, characterized in that a first rolling pass is carried out in the roll-profiling device at a temperature of the first preheated region (A, C, D) which is higher than the austenitizing temperature A_r3 of the sheet metal semifinished product (2).
10. Process according to one of Claims 3 to 9, characterized in that at least one further rolling pass is carried out in the roll-profiling device at a temperature of the second preheated region (A, C, D) which is higher than the austenitizing temperature A_r3 of the sheet metal semifinished product (2).
11. Process according to one of Claims 1 to 10, characterized in that, after each forming step, the region (A, C, D) in each case formed during this is cooled to a temperature which is lower than a transformation temperature M_s of the sheet metal semifinished product (2) at which, during rapid cooling, a transformation from austenite to martensite takes place abruptly.
12. Process according to one of Claims 1 to 11, characterized in that, after profiling, the sheet metal semifinished product (2) is calibrated in a calibrating tool.
13. Process according to Claim 12, characterized in that a further rolling pass (calibrating pass) is carried out in the calibrating tool.
14. Process according to one of Claims 1 to 13, characterized in that the profile component (1) is cut to its desired length in a separating and cutting device.

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