Method for heating a blank and heating system

Abstract

The present disclosure relates to methods for manufacturing a component from a blank. The method comprises placing the blank on a conveyor system and conveying the blank towards a furnace. The method further comprises preheating one or more preselected areas of the blank while conveying the blank towards the furnace, wherein the preselected areas of the blank are preheated by laser heating with one or more laser heating heads. Finally, the method comprises conveying the blank through the furnace. The present disclosure further relates to a preheating system for heating blanks in a production line.

Description

METHOD FOR HEATING A BLANK AND HEATING SYSTEM

[0001] The present application claims the benefit of EP23382780.7 filed on July 26th, 2023.

[0002] The present disclosure relates to heating systems for heating blanks, in particular to heating systems comprising a preheating system. The present disclosure further relates to methods for manufacturing components including hot forming of blanks.BACKGROUND

[0003] In the automotive industry, the development and implementation of lightweight materials or components is becoming more important in order to satisfy criteria for manufacturing lighter vehicles. The demand for weight reduction is especially driven by the goal of reduction of CO2 emissions. Additionally, the growing concern regarding occupant safety also leads to the adoption of materials which improve the integrity and the energy absorption of the vehicle during a crash.

[0004] Press hardening, also known as Hot Forming Die Quenching (HFDQ) typically uses boron steel sheets to create stamped components with Ultra-high Strength Steel (UHSS) properties, with tensile strengths of e.g. 1.500 MPa or 2.000 MPa or even more. The increase in strength allows for a thinner gauge material to be used, which results in weight savings over conventionally cold stamped mild steel components. Throughout the present disclosure UHSS may be regarded as a steel having an ultimate tensile strength of 1.000 MPa or more, particularly after a press hardening process.

[0005] In a HFDQ process, a blank to be hot formed may be heated to a predetermined temperature e.g. austenization temperature or higher (and particularly between Ac3 and an evaporation temperature of e.g. a coating of the blank). A furnace system may be used for this purpose. By heating the blank, the strength of the blank is decreased and deformability increases i.e. to facilitate the hot stamping process.

[0006] There are several known Ultra High Strength steels (UHSS) for hot stamping and hardening. The blank to be hot formed may be made e.g. of a boron steel, coated or uncoated, such as Usibor® (22MnB5) commercially available from ArcelorMittal.

[0007] Typical vehicle components that may be manufactured using the HFDQ process include: door beams, bumper beams, cross / side members, A / B pillar reinforcements, front and rear rails, seat crossmembers and roof rails.

[0008] In order to improve the ductility and energy absorption in specific areas of a component, it is known to introduce softer regions within the same component. This improves ductility locally while maintaining the required high strength overall. By locally tailoring the microstructure and mechanical properties of certain structural components such that they comprise regions with very high strength (very hard regions), i.e. regions with high ultimate tensile strength and high yield strength and regions with increased ductility (softer regions), i.e. regions with lower ultimate tensile strength and lower yield strength and increased elongation before break, it may be possible to improve their overall energy absorption and maintain their structural integrity during a crash situation and also reduce their overall weight. Such soft zones may also advantageously change the kinematic behavior in case of a collapse of a component under an impact.

[0009] Known methods of creating regions with increased ductility ("softzones" or "soft zones") in structural components of vehicles include the provision of tools comprising a pair of complementary upper and lower die units, each of the units having separate die elements (steel blocks).

[0010] The die elements may be designed to work at different temperatures, in order to have different cooling rates in different zones of the part being formed during the quenching process, and thereby resulting in different material properties in the final product e.g. soft areas which will generally have a lower ultimate tensile strength and a lower yield strength, but allow for more elongation before breaking. E.g. one die element may be cooled in order to quench the corresponding area of the component being manufactured at high cooling rates and to thereby reduce the temperature of the component rapidly and obtain a hard martensitic microstructure. Another neighboring die element may be heated in order to ensure that the corresponding portion of the component being manufactured cools down at a lower cooling rate, in order to obtain a softer microstructure, including e.g. bainite, ferrite and / or perlite. Such an area of the component may remain at higher temperatures than the rest of the component when it leaves the die.

[0011] Other methods for obtaining hot stamped components with areas of different mechanical properties include e.g. tailored or differentiated heating prior to stamping, and local heat treatments after a stamping process to change the local microstructure and obtain different mechanical properties. Yet further possibilities include the use of patchwork blanks, and Tailor Welded Blanks (TWB) combining different thicknesses and / or materials in blanks.

[0012] LIHSS may exhibit tensile strengths as high as 1.500 MPa, or even 2.000 MPa or more, particularly after a press hardening operation. Once hardened, a LIHSS may have a martensitic microstructure. This microstructure enables an increased maximum tensile strength and yield strength per weight unit.

[0013] In addition to the Ultra High Strength Steels mentioned before, more ductile steels may also be used in parts of the structural skeleton requiring energy absorption. These steels may be used in hot stamping processes but will not obtain a martensitic microstructure in the process. Ductibor® 1000 is an example of a suitable, more ductile steel.

[0014] A blank with different thicknesses may not be homogenously heated in the furnace, i.e. inner parts of the thick regions may not be sufficiently heated, and thus, the temperature in the whole blank may not be the same. In some examples, the blank may comprise different materials i.e. different properties. Such blanks may be formed e.g. by joining at least two blanks made of different material (which might also have different thicknesses). The resulting blank would therefore comprise the properties of the joined materials. An example of a blank with different thickness is shown in document WO 2020 / 002335 A1 , which discloses a method for manufacturing a unitary body side structural frame for a vehicle. The unitary body side structural frame is obtained by deforming a composite blank formed joining a plurality of blanks by forming one or more overlapping regions formed by partially overlapping the blanks.

[0015] If the entire blank is not homogeneously heated in the furnace to a predetermined temperature e.g. an austenization temperature or higher, the result of a further hot deforming process may not be satisfactory i.e. some parts of the blank may not be malleable enough to be correctly deformed and so the blank may be broken during deformation process. Furthermore, due to the insufficient temperature gradient, the ferritic-perlitic initial phase may not be completely transformed into austenite along the whole thickness of the blank, and consequently, in a subsequent quenching step, the desired microstructure e.g. martensite might not be created in those zones whichhad not been sufficiently heated. Furthermore, overheating the blanks may also lead to undesired changes of the material properties and / or may affect the coating.

[0016] A blank comprising thick regions may be left in the furnace for longer periods of time to ensure that such thick regions are adequately heated. The time the blank remains in the furnace may be modified e.g. by decreasing the speed of the conveyor system or by increasing the furnace length. Depending on the process, some furnace or furnace systems may be 25 meters long, or more, and moreover, as the length of the furnace grows, the occupied space increases accordingly. However, with such alternatives, the overall processing time may be substantially increased.

[0017] Document WO 2018 / 115298 A1 discloses a method for manufacturing a steel component from a blank comprising retaining the blank at a predetermined preheating location before the furnace. However, the system disclosed in WO 2018 / 115298 A1 has been found to be less than ideal for preheating blanks of very large size, like e.g. unitary door rings. Also, retaining the blank slows down the production process.

[0018] There is a need for methods and tools for processing blanks which at least partially solve some of the aforementioned problems.SUMMARY

[0019] In a first aspect, a method for manufacturing a component from a blank is provided. The method comprises placing the blank on a conveyor system and conveying the blank towards a furnace. The method further comprises preheating one or more preselected areas of the blank while conveying the blank towards the furnace. The method also comprises conveying the blank through the furnace. In the method, preheating comprises laser heating the preselected areas of the blank with one or more laser heating heads.

[0020] Heating the preselected areas of the blank with one or more laser heating heads enables preheating the preselected areas in a fast and efficient manner. Laser heating provides a precise heating of the preselected areas and enables preheating specific areas of blanks with a wide variety of sizes and geometries. No extra time is needed in order to preheat the preselected areas and a high throughput can be maintained throughout the whole heating operation. The one or more preselected areas are preheated while the blank is being conveyed towards the furnace, enabling heating of the preselected areas in a continuous non-stop operation. In addition, the temperature of the preheated areas is not decreased as a consequence of beingtransferred from the preheating system to the furnace since preheating occurs on the same conveyor that leads the blanks to the furnace.

[0021] In some examples, the laser heating heads may be multi-axis laser heating heads. This allows adjustment of the direction of the laser beam. Preselected areas of blanks with different sizes and geometries may be accurately preheated.

[0022] In some examples, preheating may further comprise moving the one or more laser heads perpendicular to a conveying direction of the blank. As the blanks move along a conveying direction, the lasers may move transverse to this direction and reach different areas of the blanks as needed. Different blanks may have different heating needs. The laser heating heads may be able to be adjusted to the dimensions and characteristics of each blank. The intensity of the heating treatment may be modified and laser heating may be adjusted to the needs of different blanks and / or different areas of the blanks. The speed of movement of the laser heating head(s), and a size of a laser spot, and an orientation of the laser heating head(s) may be varied during operation, and particularly depending on the selected regions that are to be preheated.

[0023] In some examples, preheating may comprise preheating with a first laser heating head and a second laser heating head. In further examples, preheating may comprise preheating with a first laser heating head which may be movable in a direction perpendicular to a conveying direction of the blank and preheating with a second laser heating head downstream the first laser heating head, the second laser heating head being movable in a direction perpendicular to a conveying direction of the blank.

[0024] In some examples, the preselected areas may comprise areas of the blank with increased thickness. Heating time in the furnace may be decreased and the length of the furnace may be reduced. The heating process may be improved.

[0025] In some examples, the preheating may be done in 10 seconds or less.

[0026] In some examples, the preheating step may comprise heating at least a preselected area of the blank below an Ac3 temperature, specifically between 300 - 820 °C, more specifically between 500 - 700 °C.

[0027] In a further aspect, a heating system for heating blanks in a production line is provided. The heating system comprises a furnace and a conveyor system for conveying the blanks through the furnace and a preheating system for preheating one or more preselected areas of the blank while the blank is being conveyed towards thefurnace. The preheating system is located upstream from the furnace and comprises one or more laser heating heads.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Non-limiting examples of the present disclosure will be described in the following, with reference to the appended figures, in which:Figure 1 is a flow chart of a method for manufacturing a component from a blank;Figure 2 shows a side view of a production line according to an example of the present disclosure;Figures 3a-3b show an example of a preheating system;Figures 4a - 4c schematically illustrate blanks having areas with different thickness.

[0029] The figures refer to example implementations and may only be used as an aid for understanding the claimed subject matter, not for limiting it in any sense.DETAILED DESCRIPTION OF EXAMPLES

[0030] In these figures, the same reference signs have been used to designate matching elements.

[0031] Figure 1 represents a flow chart of a method for manufacturing a component from a blank. The method comprises placing the blank on a conveyor system and conveying the blank towards a furnace 402; preheating one or more preselected areas of the blank while conveying the blank towards the furnace 404; conveying the blank through the furnace 406; wherein preheating comprises laser heating the preselected areas of the blank with one or more laser heating heads.

[0032] At step 402, a blank may be placed in a conveyor system e.g. by an industrial transfer robot. In some examples, the blank may comprise different thickness. The blank may be made from ultra-high strength steel or aluminium.

[0033] The blank may be preheated, at step 404, while it is being conveyed towards the furnace through e.g. conveyor rollers, parallel conveyor belts or walking beams. At step 404, preheating comprises laser heating preselected areas of the blank with one or more laser heating heads. In some examples, the preselected areas of the blank may comprise the areas of the blank with increased thickness.

[0034] In some examples, the laser heating heads may be multi-axis laser heating heads. In other examples, the laser heads may be moved in a direction perpendicular to a conveying direction of the blank.

[0035] Preheating may comprise preheating with a first laser heating head and with a second laser heating head. The preselected area of the blank may be heated below an Ac3 temperature, specifically between 300 - 820 °C, more specifically between 500 - 700 °C.

[0036] The blank is conveyed through the furnace at step 406. In the furnace, the blank may be heated to above the Ac3 temperature. After heating, the heated blank may exit the furnace and may be transferred to a press tool e.g. by an industrial transfer robot, where it may be hot stamped. The blank may also be entirely or partially quenched in the press tool. The dies of the press tool may be cooled appropriately, e.g. by conducting cold water or another cooling through conduits in the dies.

[0037] In some examples, the entire blank / component may be rapidly cooled, i.e. at a rate above a critical cooling rate such that a martensitic microstructure is obtained in substantially the whole component. In other examples, soft zones may be created in the component by differential cooling in the dies. Parts of the dies may be heated to avoid rapid cooling and to create another microstructure, e.g. bainite, ferrite, perlite or mixtures thereof. Optionally, the blank may further be subjected to post processing steps such as e.g. cutting, trimming, and / or joining to further components using e.g. welding.

[0038] Figure 2 shows a blank 300 in a production line 100. The process as described with respect to figure 1 may be carried out in a production line as shown in figure 2.

[0039] The production line 100 may be e.g. a hot deformation or hot stamping production line which may comprise a conveyor system 120 to transport the blank 300 through the production line 100. The conveyor system 120 may comprise e.g. a plurality of conveyor rollers, parallel conveyor belts or walking beams. The conveyor system 120 in such a case may be driven using e.g. motors. In this case, the speed of the conveyor system 120 may be controlled by controlling the speed of the motors.

[0040] According to an example, the conveyor system 120 may comprise a feeding system for placing the blank on the conveyor system and a furnace conveyor system to transport the blank through the furnace.

[0041] As shown in figure 2, the blank 300 is placed on the conveyor system 120 and is conveyed towards a furnace 130. The blank may be placed on the conveyor system by an industrial transfer robot e.g. after being cut from a steel coil.

[0042] In the production line 100, one or more preselected areas of the blank are preheated while the blank is being conveyed towards the furnace. Preheating is done in a preheating system 110 and comprises laser heating the preselected areas of the blank with one or more laser heating heads. In some examples, the preheating system 110 may comprise one or more laser heating heads which are enclosed in a laser cell 113 upstream the furnace.

[0043] A fast and precise heating of the preselected areas of the blank may be ensured by preheating with one or more laser heating heads. In addition, laser heating may enable heating areas of the blank which may not easily be heated with other heating technologies e.g. infrared heating, due to e.g. geometry and / or size of the blank.

[0044] After preheating of the blank 300, the blank 300 is conveyed through the furnace 130 where it may be heated to a predetermined temperature, e.g. above an austenization temperature, so as to prepare the blank 300 for subsequent processes. In particular, the blank may be heated to Ac3 or above.

[0045] The furnace temperature and the time that the blank remains in the furnace may vary depending on the blank material and the coating of the blank. When the blank has been subjected to a preheating process, the time in the furnace may be reduced compared to the time in the furnace of those blanks which have not had a preheating process. In particular, furnace time may be increased to ensure that the thickest portions of the blank are fully austenitic. By preheating those thickest portions, the overall time in the furnace can be reduced. A high throughput in the production line may be maintained.

[0046] The heated blank 300 may exit the furnace 130 through a door (not shown) configured to open when the blank 300 arrives, and to close again when the blank 300 has left the furnace 130. The blank 300 may be transported by a conveyor system 120, e.g. a conveyor belt or a roller conveyor, to a centering system, e.g. a centering table, to be correctly positioned for subsequent processing.

[0047] A centering table may comprise a plurality of centering pins which can be passive or can be actively moved to correctly position and center the blank 300.

[0048] After being centered and correctly positioned, the blank 300 may be transferred to a press tool for deforming and quenching. The blank 300 may be transferred to the press tool by a transferring system, e.g. one or more industrial transfer robots, which may pick up the blank 300 from the conveyor system 120 and may place it on the press tool. The transfer robot(s) may comprise a plurality of gripping units to grab and pick up the blank 300 from the conveyor means 120.

[0049] As mentioned before, the pressing tool may be provided with cooling means (not shown) e.g. water supplies or any other suitable means, to quench the blank 300 simultaneously to the hot deforming process. The cooling or quenching may be done homogeneously for the whole blank 300. Typically, channels may be provided in the dies of the press tool through which cold water or other liquid may be conducted. This cools the contact surfaces of the press tool so that the blank is quenched.

[0050] Figures 3a and 3b show a preheating system 110 according to an example of the present disclosure. The preheating system 110 is located upstream from the furnace and comprises one or more laser heating heads 111 . In the preheating system, the blank 300 is preheated while it is being conveyed towards the furnace.

[0051] By using laser heating, specific (preselected) areas of the blank may be rapidly preheated, and a high throughput of the heating system may be maintained. Preheating of specific areas of large blanks e.g. blanks having a length and width of 1 - 2 meters (m) may be achieved in a fast efficient manner. In some examples, the preheating of one or more preselected areas of the blank may be done in 15 seconds or less, specifically 10 seconds or less.

[0052] The laser heating heads may be located in a support structure 112. In some examples, the laser heating heads 111 may move along the support structure 112 e.g. through rails or along a suitable guide. The position of the laser heating heads may be adjusted depending on the location of the preselected area of the blank. This may ensure that any area of the blank is reached, and therefore preheated, by the laser heating heads no matter the size and the geometry of the blank. In some examples, the laser heating heads 111 may be enclosed in a laser cell 113 (shown in figure 2). The laser cell may comprise a protective housing to avoid exit of the laser beams.

[0053] In some examples, the laser heating heads 111 may be moved perpendicular to a conveying direction of the blank. One or more guides or rails may extend transverse across the conveyor and the lasers may move transverse to the conveying direction of the blank and the laser heating process may be adjusted to the needs ofdifferent blanks and / or different areas of the blanks. In some examples, multiple lasers may be mounted on the same guide or rail. In other examples, each guide or rail carries an individual laser.

[0054] In some examples, the laser heating heads may be multi-axis laser heating heads. The direction of the laser beam may be adjusted by rotating the laser head. In some examples, the laser heating head may have suitable optical means to vary a spot size.

[0055] Further, the power of the laser heating heads 111 may be regulated in some examples, such that the amount of heat delivered by the laser heating head may be controlled and different heating temperatures may be achieved. For example, a laser power may be varied between 3 - 15 kW. The preheating step may comprise heating at least a preselected area of the blank below an Ac3 temperature e.g. between 300 - 820 °C. In some examples a preselected area of the blank may be preheated at a temperature between 500 - 700 °C.

[0056] Preheating may comprise preheating with a first laser heating head and with a second laser heating head. In some examples, the first laser heating head may heat a first preselected area of the blank, and the second laser heating head may heat a second preselected area of the blank. In other examples, the first and second laser heating heads may heat the same preselected area of the blank. The second laser heating head may be located downstream the first laser heating head. Fast and precise heating of preselected areas of the blank may be achieved.

[0057] In some examples, the preheating system 110 may comprise a first laser heating head movable in a direction perpendicular to a conveying direction of the blank, and a second laser heating head, downstream the first laser heating head, that is also movable in a direction perpendicular to a conveying direction of the blank.

[0058] Further, preheating may comprise preheating only preselected areas 360 of the blank. Preheating only a preselected area of the blank may reduce the overall heating time in the furnace i.e. the blank may reach a target temperature in less time and the overall heating process may be optimized.

[0059] In some examples, the blank may be formed by a plurality of blanks or subblanks joined to each other.

[0060] Figures 4a - 4c show examples of blanks comprising areas with different thickness. In the examples shown in these figures, the blanks are formed by a plurality of sub-blanks.

[0061] As shown in figures 4a-4b, examples of a blank having areas with different thickness may be a blank formed by a plurality of sub-blanks which are joined by forming one or more overlapping regions with each other. In such examples, the blank may comprise increased thickness in the one or more overlapping regions as compared to the remainder of the blank. The overlaps may be arranged in areas in which specific strength or strength may be required e.g. for absorbing impacts.

[0062] In examples, individual sub-blanks may have a thickness of 0,8 - 2mm, for example 1 ,2 mm. If both sub-blanks have a thickness of 1 ,2 mm, the thickness may be 2,4 mm in the area of overlap.

[0063] In some examples, preheating a preselected area 360 of the blank with one or more laser heating heads 111 may comprise preheating at least one overlapping region 350 of the blank 300. In other examples, preheating a preselected area of the blank 360 with one or more laser heating heads 111 may comprise preheating all the overlapping regions of the blank.

[0064] Specifically, larger blanks comprising length and width of e.g. 1 - 2 meters or more, may be efficiently heated with the herein described systems and methods. In some examples, the blanks with overlapping regions may comprise blanks which after forming may be at least one of a unitary roof ring of a vehicle, a unitary rear ring of a vehicle, unitary door ring of a vehicle, a unitary firewall panel of a vehicle, a frame for the protection of a battery box of a vehicle and a unitary bumper beam assembly of a vehicle. Overall heating process may be improved and a high throughput in a hot stamping production line may be achieved.

[0065] Figure 4a shows an example of a blank before being deformed to form a unitary roof ring of a vehicle. As shown in figure 4a, the unitary roof ring may be made from four sub-blanks, a first sub-blank 310, a second sub-blank 320, a third sub-blank 330 and a fourth sub-blank 440, wherein the first and second sub-blanks 310, 320 may be longitudinal beam blanks, and the third and fourth sub-blanks 330, 340 may be cross beam blanks. The longitudinal beam blanks may be joined to the front cross beam blank and to the rear cross beam blank, forming a substantially closed ring shape. The blanks may be joined to each other e.g. through laser welding or spot welding.

[0066] The sub-blanks may be joined with each other by forming one or more overlapping regions 350 formed by partially overlapping the sub-blanks with each other. That is, one sub-blank is only partially positioned over another sub-blank and the sub-blanks are then joined to each other. An overlapping region thus acquires an increased thickness as compared to the remainder of the blanks. Such an increase in thickness can be used to tailor mechanical properties as needed and provide local reinforcements, e.g. in areas where increased strength and / or stiffness are required.

[0067] One or more of the overlapping regions 350 may be preselected areas 360 of the blank which will be preheated while the blank is being conveyed towards the furnace. The overlapping regions 350 may be heated by the same laser heating head or by different laser heating heads.

[0068] When the blank is being conveyed towards the furnace, the blank may comprise overlapping regions located more upstream in a conveying direction and overlapping regions located more downstream in the conveying direction. In this particular example, the overlapping regions in the blank located more upstream may be the overlapping regions formed by partially overlapping the third sub-blank 330 with the first and second sub-blanks 310, 320. These overlapping regions may be heated by a first laser heating head. Further, the overlapping regions located more downstream, which in this example may be the overlapping regions formed by partially overlapping the fourth subblank 340 with the first and second sub-blanks 310, 320, may be heated by a second laser heating head located downstream from the first laser heating head. For example, a first laser heating head may be movable mounted along a first guide or rails extending transverse to the conveying direction, and the second laser heating head may be movable along a second guide or rails extending transverse to the conveying direction, but being arranged more downstream in the conveying direction.

[0069] In a further example, one of the two laser heating heads may subsequently heat portions on a left side of a blank to be heated, and the other of the two laser heating heads may subsequently heat portions on a right side of the blank to be heated.

[0070] Also shown in figure 4a, a patch blank 370 may be joined to at least one of the plurality of the sub-blanks that form blank 300. A patch blank may be regarded herein as a blank that entirely overlaps another blank, i.e. a patch blank may be positioned entirely within a perimeter of another blank. The patch blank may be joined to the other blank by welding, e.g. spot welding or remote laser welding. The resulting combination of “basic” blank and patch blank may sometimes be referred to as “patchwork blank”.

[0071] A patch blank 370 may be added as a reinforcement in order to increase strength of a specific area of the blank 300. The overlapping region formed by overlapping a patch blank 370 with another blank comprises increased thickness as compared to the remainder areas of the blank. In some examples, preheating one or more preselected areas of the blank may comprise preheating an area of the blank comprising a patch blank.

[0072] The overlapping regions of the blank comprise areas of the blank with increased thickness. In some examples, preheating a preselected area 360 of the blank may comprise preheating at least one overlapping region of the blank 300. In other examples, preheating a preselected area of the blank may comprise preheating all the overlapping regions of the blank 300 e.g. the overlapping regions formed by partially overlapping the blanks with each other and the regions comprising patch blanks.

[0073] Figure 4b shows another example of a blank having areas with different thickness. Figure 4b shows a blank before being deformed to form a unitary body side structural frame of a vehicle. The blank in figure 4b is formed by joining two sub-blanks, the first sub-blank 310 to a second sub-blank 320. The first sub-blank 310 and the second sub-blank 320 partially overlap in the overlapping region 350. In this example, the upper part of the first sub-blank 310 is edge to edge laser welded to the second sub-blank 320 through the welding line 19.

[0074] In the example of figure 4b, the first sub-blank 310 and the second sub-blank 320 are spot welded through the overlapping region 350. In this specific example, the overlapping region 350 is located in the lower part of the first blank 10. The upper part of the first blank 310 may be laser welded to the second blank 320 through a laser welding line 19.

[0075] In this example, a preselected area 360 of the blank to be preheated while conveying the blank towards the furnace may be overlapping region 350, which will have increased thickness as compared to the other areas of the blank. The blank 300 may be transported through a conveyor system and the overlapping region 350 of the blank may be preheated by one or more laser heating heads. In the furnace, a predetermined temperature of the blank 300 may be reached in less time.

[0076] Figure 4c schematically illustrates another example of a blank comprising areas with different thickness. For example a floor panel may be hot stamped from such a blank.

[0077] As shown in figure 4c, the blank 300 may be a Tailor Welded Blank (TWB), which may be formed by joining a plurality of sub-blanks 310, 320 by edge-to-edge welding e.g. laser welding.

[0078] The plurality of sub-blanks 310, 320 may comprise different thicknesses and / or different materials. In this particular example, sub-blank 320 may comprise increased thickness than sub-blank 310. Accordingly, area 320 of blank 300 may be preheated with one or more laser heating heads 111 while the blank 300 is being conveyed towards the furnace.

[0079] The one or more laser heating heads may direct laser beams specifically to the area with increased thickness of the blank, area 320, which may be preheated to a desired temperature in a fast and efficient manner. As the thicker area of the blank has been preheated, heating the blank in the furnace may require less time. A blank with areas with different thickness may not require more time to heat in a furnace than a blank with homogeneous thickness.

[0080] In other examples, the plurality of sub-blanks forming the blank e.g. Tailor Welded Blank may be from different materials having different specific heat capacities. Each material may therefore need to be heated for a specific heating time to reach a predetermined temperature. In some examples, preheating one or more preselected areas of the blank may comprise preheating areas of the blank with higher specific heat. Heating time in the furnace may be reduced since the blank may reach a target temperature in reduced time and, consequently, length of the furnace may be decreased.

[0081] In some examples the blank or the hereinbefore described sub-blanks may be made from ultra-high strength steels (LIHSS). Boron steel, e.g. 22MnB5, or other steel compositions mentioned or referred to before may be suitable LIHSS. These blanks, e.g. boron steel blanks, may comprise an aluminum silicon coating or zinc coating.

[0082] llsibor® 1500P is an example of a 22MnB5 steel. The composition of llsibor® is summarized below in weight percentages (rest is iron (Fe) and impurities):Maximum carbon (C) (%): 0.25Maximum silicon (Si) (%): 0.4Maximum manganese (Mn) (%): 1.4Maximum phosphorus (P) (%): 0.03Maximum sulphur (S) (%): 0.01Aluminium (Al) (%): 0.01 - 0.1Maximum titanium (Ti) (%): 0.05Maximum niobium (Nb) (%): 0.01Maximum copper (Cu) (%): 0.20Maximum boron (B) (%): 0.005Maximum chromium (Cr) (%): 0.35

[0083] llsibor® 1500P may have a yield strength of e.g. 1.100 MPa, and an ultimate tensile strength of 1.500 MPa.

[0084] llsibor® 2000 is an example of a 37MnB5 steel, which is another boron steel with even higher strength. The yield strength of Usibor® 2000 may be 1.400 MPa or more, and the ultimate tensile strength may be above 1.800 MPa. The composition of Usibor® 2000 is summarized below in weight percentages (rest is iron (Fe) and impurities):Maximum carbon (C) (%): 0.36Maximum silicon (Si) (%): 0.8Maximum manganese (Mn) (%): 0.8Maximum phosphorus (P) (%): 0.03Maximum sulphur (S) (%): 0.01Aluminium (Al) (%): 0.01 - 0.06Maximum titanium (Ti) (%): 0.07Maximum niobium (Nb) (%): 0.07Maximum copper (Cu) (%): 0.20Maximum boron (B) (%): 0.005Maximum chromium (Cr) (%): 0.50Maximum molybdenum (Mb) (%): 0.50

[0085] MBW- K® 1900 is a manganese-boron steel 34MnB4 from ThyssenKrupp™ and suitable for hot stamping and the methods disclosed herein and which may have anultimate tensile strength after stamping of 1900 MPa. The chemical composition of MBW-K® 1900 is summarised below in weight in percentages:Maximum carbon (C) (%): 0.38Maximum silicon (Si) (%): 0.40Maximum manganese (Mn) (%): 1.40Maximum phosphorus (P) (%): 0.025Maximum sulphur (S) (%): 0.010Minimum aluminium (Al) (%): 0.015Maximum chromium and molybdenum (Cr + Mo) (%): 0.50Maximum titanium (Ti) (%): 0.05Maximum boron (B) (%): 0.005

[0086] MBW® 1900 is another manganese-boron steel from ThyssenKrupp™ which may have an ultimate tensile strength of 1900 MPa. It is commercially available with aluminium-silicon coatings and suitable for hot stamping and the methods disclosed herein. The chemical composition of MBW® 1900 is summarized below in weight in percentages:Maximum carbon (C) (%): 0.38Maximum silicon (Si) (%): 0.40Maximum manganese (Mn) (%): 1.40Maximum phosphorous (P) (%): 0.025Maximum sulphur (S) (%): 0.010Minimum aluminium (Al) (%): 0.1Maximum niobium (Nb) (%): 0.05Maximum titanium (Ti) (%): 0.05Maximum chromium and molybdenum (Cr + Mo) (%): 0.50Maximum boron (B) (%): 0.005

[0087] B1800HS is yet another boron steel which may have an ultimate tensile strength of about 1800 MPa and suitable for hot stamping and the methods disclosedherein. The chemical composition of B1800HS is summarized below in weight in percentages:Carbon (C) (%): 0.28 - 0.35Maximum silicon (Si) (%): 0.5Manganese (Mn) (%): 1.0 - 1.8Maximum phosphorous (P) (%): 0.025Maximum sulphur (S) (%): 0.010Aluminium (Al) (%): 0.01 - 0.06Maximum titanium (Ti) (%): 0.05Maximum boron (B) (%): 0.0050Maximum chromium and molybdenum and niobium (Cr + Mo + Nb) (%): 0.80

[0088] The plurality of sub-blanks that form the blank may comprise different material and / or thicknesses. For example, blanks of press hardenable manganese boron steels like llsibor® or MBW-K® 1900 (e.g. llsibor® 1500 and / or llsibor® 2000) may be used in the sub-blanks forming the blank. Using these types of materials in hot forming and subsequent quenching processes leads to a predominantly martensitic structure due to the Usibor®. One or more of the blanks may be made from a different material, e.g. Ductibor® 1000.

[0089] Ductibor® 1000 is another material used in hot stamping for increasing the elongation when compared to Usibor® 1500 and Usibor® 2000. The yield strength of Ductibor® 1000 may be 800 MPa or more, and the ultimate tensile strength of 1000 MPa or more. The composition of Ductibor® 1000 is summarized below in weight percentages (rest is iron (Fe) and impurities):Maximum carbon (C) (%): 0.10Maximum silicon (Si) (%): 0.6Maximum manganese (Mn) (%): 1.8Maximum phosphorus (P) (%): 0.03Maximum sulphur (S) (%): 0.01Aluminium (Al) (%): 0.01 - 0.1Maximum titanium (Ti) (%): 0.05Maximum niobium (Nb) (%): 0.10Maximum copper (Cu) (%): 0.20Maximum boron (B) (%): 0.005Maximum chromium (Cr) (%): 0.20

[0090] In other examples, the blank may comprise aluminium. The aluminium of the blank may be an aluminium alloy selected from the groups 6000 and 7000 series aluminium alloys. These series are characterized by their strength, corrosion resistance and weldability.

[0091] Although only a number of examples have been disclosed herein, other alternatives, modifications, uses and / or equivalents thereof are possible. Furthermore, all possible combinations of the described examples are also covered. Thus, the scope of the present disclosure should not be limited by particular examples, but should be determined only by a fair reading of the claims that follow.

Claims

CLAIMS1 . A method for manufacturing a component from a blank, the method comprising: placing the blank (300) on a conveyor system (120) and conveying the blank towards a furnace (130); preheating one or more preselected areas (360) of the blank while conveying the blank towards the furnace (130); conveying the blank (300) through the furnace (130), wherein preheating comprises laser heating the preselected areas (360) of the blank with one or more laser heating heads (111).

2. The method according to claim 1 , wherein the laser heating heads (111) are multi-axis laser heating heads.

3. The method according to claims 1 or 2, preheating further comprises moving the laser heating heads (111) in a direction perpendicular to a conveying direction of the blank.

4. The method according to claim 3, wherein a speed of the laser heating heads is varied in operation, particularly depending on the preselected areas of the blank.

5. The method according to any of claims 1 - 4, wherein a spot of a laser and / or angle of the multi-axis laser heating heads is varied, and particularly is adjusted according to the preselected areas of the blank.

6. The method according to any of claims 1 - 5, wherein preheating comprises preheating with a first laser head, and a second laser head, wherein the first laser head is arranged upstream with respect to the second laser head.

7. The method according to any of claims 1 - 6, wherein the preselected areas comprise areas of the blank with increased thickness (320, 350) as compared to other areas of the blank.

8. The method according to any of claims 1 - 7, wherein the preheating is done in 10 seconds or less.

9. The method according to any of claims 1 - 8, wherein the preheating step comprises heating at least a preselected area (360) of the blank below an Ac3 temperature, specifically between 300 - 820 °C, more specifically between 500 - 700 °C.

10. The method according to any of claims 1 - 9, wherein the furnace heats the blank to above the Ac3 temperature.11 . The method according to any of claims 1 - 10, further comprising: transferring the heated blank to a press tool; hot stamping the blank; and quenching the blank.

12. A heating system for heating blanks in a production line, the heating system comprising: a furnace (130); a conveyor system (120) for conveying the blanks through the furnace (130); and a preheating system (110) for preheating one or more preselected areas (360) of a blank (300) while the blank is being conveyed towards the furnace (130), wherein the preheating system (110) is located upstream from the furnace (130) and comprises one or more laser heating heads (111).

13. The heating system according to claim 11 , wherein the laser heating heads (111) are multi-axis laser heating heads.

14. The heating system according to any of claims 11 - 12, wherein the preheating system (110) comprises a first laser heating head movable in a direction perpendicular to a conveying direction of the blank.

15. The heating system according to claim 13, wherein the preheating system comprises a second laser heating head downstream the first laser heating head, the second laser heating head movable in a direction perpendicular to a conveying direction of the blank.

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