Method for heating slab and heating system

Abstract

The present disclosure relates to a method of manufacturing a component from a slab. The method includes placing a slab on a conveying system and conveying the slab to a heating furnace. The method further includes preheating one or more pre-selected areas of the slab while the slab is being conveyed to the heating furnace, where the pre-selected areas of the slab are preheated by one or more laser heating heads in a laser heating manner. Finally, the method includes conveying the slab through the heating furnace. The present disclosure also relates to a preheating system for heating a slab on a production line.

Description

TECHNICAL FIELD

[0001] This application claims priority from EP 23382780.7 filed on 26 July 2023.

[0002] The present disclosure relates to a heating system for heating a slab, in particular to a heating system comprising a preheating system. The present disclosure also relates to a method for manufacturing a hot formed component comprising a slab. BACKGROUND

[0003] In the automotive industry, the development and implementation of lightweight materials or components has become increasingly important in order to comply with the guidelines for manufacturing lighter vehicles. The demand for weight reduction is driven, inter alia, by the goal of reducing carbon dioxide emissions. In addition, the increasing focus on occupant safety also prompts the adoption of materials that can improve the integrity and energy absorption of vehicles upon impact.

[0004] Hot stamping, also known as hot formed die quenching (HFDQ), generally uses a boron steel sheet to manufacture a stamped part having ultra-high strength steel (UHSS) properties, with a tensile strength of, for example, 1500 MPa or 2000 MPa or more. The strength increase allows the use of thinner gauges of material, thereby enabling weight reduction compared to traditional cold-stamped low-carbon steel components. In the present disclosure, UHSS can be considered as a steel material having an ultimate tensile strength of 1000 MPa or more, in particular after the hot stamping process.

[0005] In the HFDQ process, the slab to be hot formed can be heated to a predetermined temperature, for example an austenitizing temperature or higher (in particular between Ac3 and the evaporation temperature of the coating of the slab, for example the evaporation temperature of the coating). A heating furnace system can be used for this purpose. By heating the slab, the strength of the slab is reduced and the deformability is increased, i.e. to facilitate the hot stamping process.

[0006] Various ultra-high strength steels (UHSS) are known to be used for hot stamping and hardening. The slab to be hot formed can be made of, for example, a boron steel, with or without a coating, such as Usibor® (22MnB5) available from ArcelorMittal.

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

[0008] To improve the ductility and energy absorption in specific areas of a component, it is known to provide softer areas inside the same component. This can locally increase the ductility while maintaining the required high strength overall. By locally adjusting the microstructure and mechanical properties of certain structural components to include areas with very high strength (very hard areas), i.e. areas with high ultimate tensile strength and high yield strength, and areas with increased ductility (softer areas), i.e. areas with lower ultimate tensile strength and lower yield strength and increased elongation before fracture, it can be possible to improve their overall energy absorption and maintain their structural integrity in the event of a crash, while also reducing their overall weight. Such softer areas can also advantageously change the kinematic behavior when the component collapses under impact.

[0009] Known methods to create areas with increased ductility (softer areas ("soft zones" or "soft zones")) in structural components of vehicles include providing a tool consisting of a pair of complementary upper and lower die units, each of these units having individual die elements (steel blocks).

[0010] The die elements can be designed to work at different temperatures in order to have different cooling rates in different areas of the part being formed during quenching, so as to have different material properties in the final product, for example, softer areas typically having lower ultimate tensile strength and lower yield strength, but allowing greater elongation before fracture. For example, one die element can be cooled in order to quench the corresponding area of the component being manufactured at a high cooling rate, so as to rapidly reduce the temperature of the component and obtain a hard martensitic microstructure. Another adjacent die element can be heated in order to ensure that the corresponding portion of the component being manufactured cools at a lower cooling rate, so as to obtain a softer microstructure, including for example bainite, ferrite and / or pearlite. Such areas of the component can remain at a higher temperature than the rest of the component when it is removed from the die.

[0011] Other methods to obtain hot-stamped components with different mechanical properties include, for example, custom or differential heating before stamping, and local heat treatment after the stamping process to change the local microstructure and obtain different mechanical properties. Further possible solutions also include the use of split blanks, and laser tailor-welded blanks (TWB) combining different thicknesses and / or materials in the blank.

[0012] UHSSs can exhibit tensile strengths of up to 1500 MPa, or even 2.000 MPa or more, particularly after a press hardening operation. Once hardened, UHSSs can have a martensitic microstructure. This microstructure allows for an increase in maximum tensile strength and yield strength per unit of weight.

[0013] In addition to the aforementioned ultra-high strength steel, more ductile steel material can also be used in the structural backbone parts where energy absorption is required. These steel materials can be used in a hot stamping process, but a martensitic microstructure is not obtained in this process. Ductibor® 1000 is an example of a suitable, more ductile steel material.

[0014] Since slabs with different thicknesses can not be heated evenly in the furnace, i.e. the inner part of the thicker areas can not be heated sufficiently, the temperature of the entire slab can not be the same. In some examples, the slab can comprise different materials, i.e. have different properties. Such a slab can be formed by, for example, joining at least two slabs made of different materials, which can also have different thicknesses. The resulting slab will thus comprise the properties of the joined materials. An example of a slab with different thicknesses is shown in document WO 2020 / 002335 Al, which discloses a method for manufacturing a monocoque body side structural frame for a vehicle. The monocoque body side structural frame is obtained by deforming a composite slab formed by joining a plurality of slabs, which form one or more overlapping areas by partially overlapping the slabs.

[0015] If the entire slab is not heated evenly in the furnace to a predetermined temperature, such as the austenitizing temperature or higher, the subsequent hot deformation can not be effective, i.e. certain parts of the slab can not be sufficiently forgeable to deform correctly, and thus the slab can break during the deformation process. Furthermore, due to insufficient temperature gradients, the ferrite-pearlite initial phase can not fully transform to austenite along the entire thickness of the slab, and thus, in the subsequent quenching step, those areas that are not heated sufficiently can not form the desired microstructure, such as martensite. In addition, overheating of the slab can also cause undesirable changes in the properties of the material and / or can affect the coating.

[0016] Slabs comprising thick areas can be placed in the furnace for a longer time to ensure that such thick areas are heated sufficiently. The time the slab spends in the furnace can be adjusted by, for example, reducing the speed of the conveying system or increasing the length of the furnace. Depending on the process, certain furnaces or furnace systems can be as long as 25 meters or more, and with the increase in the length of the furnace, the space occupied also increases accordingly. However, with such alternatives, the overall processing time can increase significantly.

[0017] Document WO 2018 / 115298 Al discloses a method of manufacturing a steel part from a slab, which comprises retaining the slab at a predetermined preheating location before entering the furnace. However, it has been found that the system disclosed in WO 2018 / 115298 Al is not ideal for preheating very large slabs, such as monolithic door rings. In addition, retaining the slab slows down the production process.

[0018] There is a need for a method and an apparatus for handling slabs to at least partially address some of the problems described above. SUMMARY

[0019] In a first aspect, a method of manufacturing a component from a slab is provided. The method includes placing a slab on a conveying system and conveying the slab to a furnace. The method also includes preheating one or more preselected areas of the slab while the slab is being conveyed to the furnace. The method further includes conveying the slab through the furnace. In the method, the preheating includes laser heating the preselected areas of the slab using one or more laser heating heads.

[0020] The use of one or more laser heating heads to heat the preselected areas of the slab enables the preselected areas to be preheated in a fast and efficient manner. Laser heating enables precise heating of the preselected areas and enables preheating of specific areas of slabs of various sizes and geometries. The preheating of the preselected areas does not require additional time and enables high productivity throughout the heating operation. The preselected areas can be preheated while the slab is being conveyed to the furnace, thereby enabling the preselected areas to be heated in a continuous and uninterrupted operation. Furthermore, since the preheating is performed on the same conveyor on which the slab is being conveyed to the furnace, the temperature of the preheated areas does not decrease when the slab is conveyed from the preheating system to the furnace.

[0021] In some examples, the laser heating heads can be multi-axis laser heating heads. This enables the direction of the laser beams to be adjusted. Precise preheating of the preselected areas of slabs of various sizes and geometries is enabled.

[0022] In some examples, the preheating can further include moving the one or more laser heads perpendicular to the direction of conveyance of the slab. As the slab moves in the direction of conveyance, the laser can move transverse to the direction and reach different areas of the slab as needed. Different slabs can have different heating requirements. The laser heating heads can be able to be adjusted according to the size and characteristics of each slab. The intensity of the heating treatment can be modified and the laser heating can be adjusted according to the requirements of different slabs and / or different areas of the slab. The speed of movement of the laser heating heads, the size of the laser spots, and the orientation of the laser heating heads can be varied throughout the operation, in particular depending on the areas selected to be preheated.

[0023] In some examples, the preheating can include preheating using a first laser heating head and a second laser heating head. In further examples, the preheating can include preheating using a first laser heating head that is movable in a direction perpendicular to the direction of conveyance of the slab and a second laser heating head that is downstream of the first laser heating head and is movable in a direction perpendicular to the direction of conveyance of the slab.

[0024] In some examples, the preselected regions can include regions where the slab thickness is increased. The heating time in the furnace can be reduced and the length of the furnace can be shortened. The heating process can be improved.

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

[0026] In some examples, the preheating step can include heating at least one preselected region of the slab at a temperature below the Ac3 temperature, in particular between 300°C and 820°C, more particularly between 500°C and 700°C.

[0027] In another aspect, there is provided a heating system for heating a slab on a production line. The heating system comprises a furnace and a transport system for transporting the slab through the furnace, and a preheating system for preheating one or more preselected regions of the slab during transport of the slab to the furnace. The preheating system is located upstream of the furnace and comprises one or more laser heating heads. BRIEF DESCRIPTION OF DRAWINGS

[0028] Non-limiting examples of the present disclosure will be described below with reference to the accompanying drawings, in which: Figure 1 is a flowchart of a method of manufacturing an assembly from a slab; Figure 2 shows a side view of a production line according to examples of the present disclosure; Figs. 3a-3b show examples of a preheating system; Figs. 4a-4c schematically illustrate a slab having regions of different thicknesses.

[0029] The accompanying drawings are related to example implementations and merely serve as an aid to understanding the claimed subject matter, and are not limiting in any manner. DETAILED DESCRIPTION

[0030] In the various drawings herein, like reference numerals are used to designate corresponding elements.

[0031] Figure 1 is a flowchart of a method of manufacturing an assembly from a slab; the method comprises placing the slab on a transport system and transporting the slab to a furnace 402; during transport of the slab to the furnace, preheating one or more preselected regions of the slab 404; transporting the slab through the furnace 406; wherein the preheating comprises laser heating of the preselected regions of the slab using one or more laser heating heads.

[0032] At step 402, a slab can be placed on a conveyor system, for example by an industrial transfer robot. In some examples, the slabs can have different thicknesses. The slabs can be made of ultra-high strength steel or aluminum.

[0033] At step 404, the slab can be preheated during its transport to a heating furnace, for example by conveyor rollers, parallel conveyor belts, or step beams. At step 404, the preheating includes laser heating of preselected regions of the slab using one or more laser heating heads. In some examples, the preselected regions of the slab can include regions of the slab where the thickness is increased.

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

[0035] The preheating can include preheating using a first laser heating head and a second laser heating head. The preselected regions of the slab can be heated to below the Ac3 temperature, specifically between 300°C and 820°C, more specifically between 500°C and 700°C.

[0036] At step 406, the slab is transported through a heating furnace. In the heating furnace, the slab can be heated to above the Ac3 temperature. After heating, the heated slab can exit the heating furnace and be transferred to a stamping die, for example by an industrial transfer robot, where it is hot stamped. The slab can also be fully or partially quenched in the stamping die. The die of the stamping die can be cooled as appropriate, for example by running cold water or other cooling medium through channels in the die.

[0037] In some examples, the entire slab / part can be rapidly cooled, i.e. at a rate higher than the critical cooling rate, so as to obtain substantially a martensitic microstructure in the entire part. In other examples, softer regions can be formed in the part by differential cooling in the die. Portions of the die can be heated to avoid rapid cooling and form another microstructure, for example bainite, ferrite, pearlite, or a mixture thereof. Optionally, the slab can also be further subjected to post-processing steps, such as cutting, trimming, and / or joining with other parts, for example by welding.

[0038] Figure 2 A slab 300 in a production line 100 is shown. For Figure 1 The described process can be performed in a production line as Figure 2 shown.

[0039] Production line 100 may be, for example, a hot forming or hot stamping production line, which may include a conveyor system 120 for conveying the slab 300 through production line 100. Conveyor system 120 may include, for example, multiple conveyor rollers, a parallel conveyor belt, or a walking beam. In such cases, conveyor system 120 may be driven, for example, by a motor. In this case, the speed of conveyor system 120 can be controlled by controlling the speed of the motor.

[0040] According to one example, the conveying system 120 may include a feeding system for placing slabs on the conveying system and a furnace conveying system for conveying the slabs through a furnace.

[0041] like Figure 2 As shown, slab 300 is placed on conveyor system 120 and conveyed to heating furnace 130. The slab can be placed on the conveyor system by an industrial transfer robot, for example, after being cut from a steel coil.

[0042] In production line 100, when a slab is conveyed to a heating furnace, one or more pre-selected areas of it can be preheated. Preheating takes place in a preheating system 110 and includes laser heating of the pre-selected areas of the slab using one or more laser heating heads. In some examples, the preheating system 110 may include one or more laser heating heads enclosed in a laser unit 113 upstream of the heating furnace.

[0043] Preheating using one or more laser heating heads ensures rapid and precise heating of pre-selected areas of the slab. Furthermore, laser heating can be used to heat areas of the slab that are difficult to heat using other heating techniques (such as infrared heating) due to their geometry and / or size.

[0044] After preheating, slab 300 is conveyed through heating furnace 130, where it can be heated to a predetermined temperature, such as above the austenitizing temperature, in order to prepare slab 300 for subsequent processes. Specifically, the slab can be heated to Ac3 temperature or above.

[0045] The furnace temperature and the residence time of the slab in the furnace can vary depending on the slab material and coating. When the slab is preheated, its residence time in the furnace can be shortened compared to that of an unpreheated slab. Specifically, the residence time in the furnace can be increased to ensure that the thickest parts of the slab are fully transformed into austenite. By preheating these thickest parts, the total residence time of the slab in the furnace can be shortened, thereby maintaining high productivity on the production line.

[0046] The heated slab 300 can be ejected from the heating furnace 130 through a door (not shown) configured to open when the slab 300 arrives and to close again after the slab 300 has left the heating furnace 130. The slab 300 can be transported by the conveying system 120, e.g. a conveyor belt or roller conveyor, to a centering system, e.g. a centering table, for correct positioning for subsequent processing.

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

[0048] The slab 300, after being centered and correctly positioned, can be transferred to a press tool for deformation and quenching. The slab 300 can be transferred to the press tool by a transfer system, e.g. one or more industrial transfer robots, which can pick up the slab 300 from the conveying system 120 and place it on the press tool. The transfer robots can comprise a plurality of gripping units for gripping and picking up the slab 300 from the conveying device 120.

[0049] As mentioned before, the press tool can be equipped with cooling means (not shown), e.g. water supply means or any other suitable means, to quench the slab 300 simultaneously during the hot deformation. The entire slab 300 can be uniformly cooled or quenched. Typically, channels can be provided in the dies of the press tool through which cold water or other liquid can be supplied. This cools the contact surfaces of the press tool, thereby quenching the slab.

[0050] Figures 3a and 3b show a preheating system 110 according to examples of the present disclosure. The preheating system 110 is located upstream of the heating furnace and comprises one or more laser heating heads 111. In the preheating system, the slab 300 is preheated during transport to the heating furnace.

[0051] By using laser heating, specific (preselected) areas of the slab can be quickly preheated, and the high production rate of the heating system can be maintained. Preheating of specific areas of large slabs, e.g. slabs having a length and width of 1 to 2 meters (m), can be achieved quickly and efficiently. In some examples, preheating of one or more preselected areas of the slab can be completed in 15 seconds or less, in particular in 10 seconds or less.

[0052] The laser heating head can be located in the support structure 112. In some examples, the laser heating head 111 can be moved along the support structure 112, for example by a track or along a suitable guide rail. The position of the laser heating head can be adjusted depending on the location of the preselected area of the slab. This can ensure that the laser heating head can reach any area of the slab regardless of the size and geometry of the slab, and thus preheat it. In some examples, the laser heating head 111 can be enclosed in a laser unit 113 (as shown in Figure 2 The laser unit can comprise a protective housing to prevent the laser beam from escaping.

[0053] In some examples, the laser heating head 111 can be moved perpendicular to the direction of transport of the slab. One or more guide rails or tracks can traverse the conveyor, the laser can be moved transversely to the direction of transport of the slab, and the laser heating process can be adjusted as needed for different slabs and / or different areas of the slab. In some examples, multiple lasers can be mounted on the same guide rail or track. In other examples, each guide rail or track carries a separate laser.

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

[0055] Furthermore, in some examples, the power of the laser heating head 111 can be adjusted, so that the amount of heat delivered by the laser heating head can be controlled, and different heating temperatures can be achieved. For example, the laser power can vary between 3 kW and 15 kW. The preheating step can comprise heating at least one preselected area of the slab to a temperature below the Ac3 temperature, for example between 300 °C and 820 °C. In some examples, the preselected area of the slab can be preheated at a temperature of 500 °C to 700 °C.

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

[0057] In some examples, the preheating system 110 can comprise a first laser heating head that can be moved in a direction perpendicular to the direction of transport of the slab, and a second laser heating head located downstream of the first laser heating head, which can also be moved in a direction perpendicular to the direction of transport of the slab.

[0058] Further, the preheating can include preheating only preselected regions 360 of the slab. Preheating only preselected regions of the slab can shorten the overall heating time in the furnace, i.e. the slab can reach the target temperature in a shorter time, and the overall heating process can be optimized.

[0059] In some examples, the slab can be formed from a plurality of mutually joined slabs or sub-slabs.

[0060] Figures 4a to 4c show examples of slabs comprising regions of different thicknesses. In these illustrated examples, the slabs are formed from a plurality of sub-slabs that are joined to one another.

[0061] As shown in Figures 4a to 4b, an example of a slab having regions of different thicknesses can be a slab formed from a plurality of sub-slabs that are joined to one another to form one or more overlapping regions. In such examples, the slab can comprise an increased thickness in the one or more overlapping regions compared to the rest of the slab. The overlapping regions can be arranged in areas where a particular strength or strength is required, for example for absorbing impacts.

[0062] In examples, the thickness of the individual sub-slabs can be 0.8 mm to 2 mm, for example 1.2 mm. If the thickness of both sub-slabs is 1.2 mm, the thickness in the overlapping region can be 2.4 mm.

[0063] In some examples, preheating a preselected region 360 of the slab 300 using the one or more laser heating heads 111 can include preheating at least one overlapping region 350 of the slab 300. In other examples, preheating a preselected region of the slab 360 using the one or more laser heating heads 111 can include preheating all overlapping regions of the slab.

[0064] In particular, large slabs having a length and width of, for example, 1 meter to 2 meters or more can be efficiently heated using the systems and methods described herein. In some examples, the slab having overlapping regions can comprise a slab that, after forming, is at least one of a unitized roof ring of a vehicle, a unitized rear ring of a vehicle, a unitized door ring of a vehicle, a unitized firewall panel of a vehicle, a vehicle battery box protection frame, and a unitized bumper beam assembly of a vehicle. The overall heating process can be improved and high production rates can be achieved in a hot stamping production line.

[0065] Fig. 4a shows an example of the blanks before being deformed to form a monolithic roof ring of a vehicle. As shown in Fig. 4a, the monolithic roof ring can be made of four sub-blanks, including a first sub-blank 310, a second sub-blank 320, a third sub-blank 330, and a fourth sub-blank 440, wherein the first sub-blank 310 and the second sub-blank 320 can be longitudinal beam blanks, and the third sub-blank 330 and the fourth sub-blank 340 can be transverse beam blanks. The longitudinal beam blanks can be joined with the front and rear transverse beam blanks to form a substantially closed ring. The blanks can be joined with each other by, for example, laser welding or spot welding.

[0066] The sub-blanks can be joined with each other by partially overlapping the sub-blanks to form one or more overlapping regions 350. That is, one sub-blank is positioned only partially on another sub-blank, and then the sub-blanks are joined with each other. As a result, the thickness of the overlapping regions is increased compared to the rest of the blank. Such an increase in thickness can be used to adjust the mechanical properties as needed, and to provide local reinforcement, for example, in areas where higher strength and / or stiffness is needed.

[0067] The one or more overlapping regions 350 can be preselected regions 360 of the blank that are to be preheated during the process of transporting the blank to the furnace. The overlapping regions 350 can be heated by the same laser heating head or by different laser heating heads.

[0068] When the blank is transported to the furnace, the blank can include overlapping regions that are more upstream in the direction of transport and overlapping regions that are more downstream in the direction of transport. In this particular example, the more upstream overlapping regions in the blank can be formed by the third sub-blank 330 partially overlapping the first sub-blank 310 and the second sub-blank 320. These overlapping regions can be heated by a first laser heating head. In addition, the more downstream overlapping regions (in this example, the overlapping regions can be the overlapping regions formed by the fourth sub-blank 340 partially overlapping the first sub-blank 310 and the second sub-blank 320) can be heated by a second laser heating head that is positioned downstream of the first laser heating head. For example, the first laser heating head can be movably mounted along a first guide or track that is perpendicular to the direction of transport, and the second laser heating head can be movably mounted along a second guide or track that is perpendicular to the direction of transport, but positioned more downstream in the direction of transport.

[0069] In another example, one of the two laser heating heads can subsequently heat the portion of the blank to be heated on the left side, and the other of the two laser heating heads can subsequently heat the portion of the blank to be heated on the right side.

[0070] As shown in FIG. 4a, a patch blank 370 can be joined with at least one of the plurality of sub-blanks that form the blank 300. Here, the patch blank can be considered to be a blank that completely overlaps another blank, i.e., the patch blank can be completely within the profile of another blank. The patch blank can be joined with the other blanks by welding, e.g., spot welding or remote laser welding. The resulting combination of the“base” blank and the patch blank can sometimes be referred to as a“split blank”.

[0071] The patch blank 370 can be added as a reinforcement to increase the strength of a particular region of the blank 300. The thickness of the overlap region formed by the patch blank 370 overlapping another blank is increased compared to the rest of the blank. In some examples, the preselected region or regions of the preheating blank can include regions of the preheating blank that include patch blanks.

[0072] The overlap region of the blank includes a region of the blank with increased thickness. In some examples, the preselected region 360 of the preheating blank can include at least one overlap region of the preheating blank 300. In other examples, the preselected region of the preheating blank can include all of the overlap regions of the preheating blank 300, e.g., overlap regions formed by blanks partially overlapping each other and regions including patch blanks.

[0073] FIG. 4b shows another example of a blank having regions of different thicknesses. FIG. 4b shows a blank prior to being deformed to form a unibody vehicle body side structure frame. The blank in FIG. 4b is joined from two sub-blanks, i.e., a first sub-blank 310 joined with a second sub-blank 320. The first sub-blank 310 and the second sub-blank 320 partially overlap in an overlap region 350. In this example, the upper portion of the first sub-blank 310 is edge-to-edge laser welded to the second sub-blank 320 by a weld line 19.

[0074] In the example of FIG. 4b, the first sub-blank 310 and the second sub-blank 320 are spot welded through the overlap region 350. In this particular example, the overlap region 350 is located in the lower portion of the first blank 10. The upper portion of the first blank 310 can be laser welded to the second blank 320 by the laser weld line 19.

[0075] In this example, the preselected region 360 of the blank to be preheated can be the overlap region 350, which will have an increased thickness compared to the rest of the blank, during transport of the blank to the furnace. The blank 300 can be transported by a transport system, and the overlap region 350 of the blank can be preheated by one or more laser heating heads. In the furnace, the blank 300 can reach a predetermined temperature in a shorter time.

[0076] FIG. 4c schematically illustrates another example of a blank having regions of different thicknesses. For example, a floor panel can be hot-stamped from such a blank.

[0077] As shown in FIG. 4c, the slab 300 can be a tailor-welded blank (TWB) that can be formed by joining multiple sub-slabs 310, 320 via edge-to-edge welding (e.g., laser welding).

[0078] The multiple sub-slabs 310, 320 can have different thicknesses and / or different materials. In this particular example, the thickness of the sub-slab 320 can be greater than the thickness of the sub-slab 310. Thus, during the transport of the slab 300 to the furnace, the region 320 of the slab 300 can be preheated by the one or more laser heating heads 111.

[0079] The one or more laser heating heads can direct the laser beams specifically to the region of the slab where the thickness is increased, i.e., the region 320, which can be preheated to the desired temperature in a fast and efficient manner. Since the thicker region of the slab has been preheated, the time required to heat the slab in the furnace can be less. The slab having regions of different thicknesses can not require more time to heat in the furnace compared to a slab having a uniform thickness.

[0080] In other examples, the multiple sub-slabs forming the slab (e.g., a tailor-welded blank) can be made of different materials having different specific heat capacities. Thus, each material can require a specific time to be heated to a predetermined temperature. In some examples, preheating one or more preselected regions of the slab can include preheating regions of the slab having a higher specific heat capacity. Since the slab can reach the target temperature in a shorter time, the heating time in the furnace can be reduced, which in turn can shorten the length of the furnace.

[0081] In some examples, the slab or the aforementioned sub-slabs can be made of ultra-high strength steel (UHSS). Boron steel, such as 22MnB5, or other steel compositions mentioned or referenced previously can be suitable as UHSS. These slabs (e.g., boron steel slabs) can include an aluminum-silicon coating or a zinc coating.

[0082] Usibor® 1500P is an example of a 22MnB5 steel. Usibor ® The composition of the Usibor® 1500P is summarized below in weight percentages (the remainder is iron (Fe) and impurities): Carbon (C) maximum content (%): 0.25 Silicon (Si) maximum content (%): 0.4 Manganese (Mn) maximum content (%): 1.4 Phosphorus (P) maximum content (%): 0.03 Sulfur (S) maximum content (%): 0.01 Aluminum (Al) content (%): 0.01-0.1 Titanium (Ti) maximum content (%): 0.05 Cobalt (Co) max content (%): 0.01 Copper (Cu) max content (%): 0.20 Boron (B) max content (%): 0.005 Chromium (Cr) max content (%): 0.35 Usibor ® 1500P can have a yield strength of 1100 MPa and an ultimate tensile strength of 1500 MPa.

[0083] Usibor® 2000 is an example of a 37MnB5 steel, which is another boron steel with even higher strength. Usibor ® 2000 can have a yield strength of 1400 MPa or higher and an ultimate tensile strength of 1800 MPa or more. Usibor ® The composition of Usibor® 2000 is summarized below in weight percent (the remainder being iron (Fe) and impurities): Carbon (C) max content (%): 0.36 Silicon (Si) max content (%): 0.8 Manganese (Mn) max content (%): 0.8 Phosphorus (P) max content (%): 0.03 Sulfur (S) max content (%): 0.01 Aluminum (Al) content (%): 0.01-0.06 Titanium (Ti) max content (%): 0.07 Niobium (Nb) max content (%): 0.07 Copper (Cu) max content (%): 0.20 Boron (B) max content (%): 0.005 Chromium (Cr) max content (%): 0.50 Molybdenum (Mb) max content (%): 0.50 MBW-K® 1900 is a 34MnB4 manganese-boron steel produced by ThyssenKrupp™ suitable for hot stamping and the methods disclosed herein and can have an ultimate tensile strength of 1900 MPa after stamping. The chemical composition of MBW-K® 1900 is summarized below in weight percent: Carbon (C) max content (%): 0.38 Silicon (Si) max content (%): 0.40 Manganese (Mn) max content (%): 1.40 Phosphorus (P) max content (%): 0.025 Sulfur (S) max content (%): 0.010 Minimum content of aluminum (Al) (%): 0.015 Maximum content of chromium and molybdenum (Cr + Mo) (%): 0.50 Maximum content of titanium (Ti) (%): 0.05 Maximum content of boron (B) (%): 0.005 MBW® 1900 is another manganese-boron steel produced by ThyssenKrupp™ that can have an ultimate tensile strength of 1900 MPa. The slab is commercially available with an aluminum-silicon coating and is suitable for hot-stamping processes and the methods disclosed herein. MBW ® The chemical composition of MBW 1900 is summarized below in weight percent: Maximum content of carbon (C) (%): 0.38 Maximum content of silicon (Si) (%): 0.40 Maximum content of manganese (Mn) (%): 1.40 Maximum content of phosphorus (P) (%): 0.025 Maximum content of sulfur (S) (%): 0.010 Minimum content of aluminum (Al) (%): 0.1 Maximum content of niobium (Nb) (%): 0.05 Maximum content of titanium (Ti) (%): 0.05 Maximum content of chromium and molybdenum (Cr + Mo) (%): 0.50 Maximum content of boron (B) (%): 0.005 B1800HS is another boron steel that can have an ultimate tensile strength of about 1800 MPa and is suitable for hot-stamping and the methods disclosed herein. The chemical composition of B1800HS is summarized below in weight percent: Content of carbon (C) (%): 0.28 to 0.35 Maximum content of silicon (Si) (%): 0.5 Content of manganese (Mn) (%): 1.0 to 1.8 Maximum content of phosphorus (P) (%): 0.025 Maximum content of sulfur (S) (%): 0.010 Content of aluminum (Al) (%): 0.01 to 0.06 Maximum content of titanium (Ti) (%): 0.05 Maximum content of boron (B) (%): 0.0050 Maximum content of chromium, molybdenum, and niobium (Cr + Mo + Nb) (%): 0.80 Multiple sub-slabs forming the slab may have different materials and / or thicknesses. For example, in the sub-slabs forming the slab, pressable manganese boron steel slabs such as Usibor® or MBW-K® 1900 (e.g., Usibor® 1500 and / or Usibor® 2000) can be used. The use of these types of materials in the hot forming and subsequent quenching processes is due to Usibor… ® This will form a structure dominated by martensite. One or more slabs in the slab may be made of different materials, such as Ductibor® 1000.

[0084] Ductibor® 1000 is another material used for hot stamping, similar to Usibor. ® 1500 and Usibor ® Compared to 2000, it can improve elongation. (Ductibor) ® The yield strength of 1000 can reach 800 MPa or higher, and the ultimate tensile strength can reach 1000 MPa or higher. (Ductibor) ® The composition of 1000 by weight percentage is summarized as follows (the remainder is iron (Fe) and impurities): Maximum carbon (C) content (%): 0.10 Maximum silicon (Si) content (%): 0.6 Maximum manganese (Mn) content (%): 1.8 Maximum phosphorus (P) content (%): 0.03 Maximum sulfur (S) content (%): 0.01 Aluminum (Al) content (%): 0.01-0.1 Maximum titanium (Ti) content (%): 0.05 Maximum niobium (Nb) content (%): 0.10 Maximum copper (Cu) content (%): 0.20 Maximum boron (B) content (%): 0.005 Maximum chromium (Cr) content (%): 0.20 In other examples, the slab may include aluminum. The aluminum in the slab may be an aluminum alloy selected from the 6000 and 7000 series. These series are characterized by high strength, corrosion resistance, and good weldability.

[0085] Although only a few examples are disclosed herein, other substitutions, modifications, uses, and / or equivalents are possible. Furthermore, all possible combinations of the described examples are covered. Therefore, the scope of this disclosure should not be limited to the specific examples but should be determined solely by a reasonable reading of the appended claims.

Claims

1. A method for manufacturing a component using a slab, the method comprising: The slab (300) is placed on the conveying system (120) and conveyed to the heating furnace (130). While the slab is being conveyed to the heating furnace (130), one or more pre-selected areas (360) of the slab are preheated; The slab (300) is conveyed through the heating furnace (130), wherein preheating includes laser heating of the preselected area (360) of the slab with one or more laser heating heads (111).

2. The method according to claim 1, wherein the laser heating head (111) is a multi-axis laser heating head.

3. The method according to claim 1 or 2, the preheating further includes moving the laser heating head (111) in a direction perpendicular to the conveying direction of the slab.

4. The method of claim 3, wherein the speed of the laser heating head varies during operation, particularly depending on the pre-selected region of the slab.

5. The method according to any one of claims 1 to 4, wherein the laser spot and / or the angle of the multi-axis laser heating head change, particularly adjusted according to the pre-selected region of the slab.

6. The method according to any one of claims 1 to 5, wherein preheating includes preheating using a first laser head and a second laser head, wherein the first laser head is disposed upstream of the second laser head.

7. The method according to any one of claims 1 to 6, wherein the preselected region includes a region with increased thickness (320, 350) compared to other regions of the slab.

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

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

10. The method according to any one of claims 1 to 9, wherein the heating furnace heats the slab to above the Ac3 temperature.

11. The method according to any one of claims 1 to 10, further comprising: The heated slab is transferred to a stamping die; The slab is hot-stamped; as well as The slab is then quenched.

12. A heating system for heating slabs on a production line, the heating system comprising: Heating furnace (130); A conveying system (120) for conveying the slab through the heating furnace (130). as well as A preheating system (110) is used to preheat one or more preselected areas (360) of a slab (300) while the slab (300) is being conveyed to the heating furnace (130), wherein the preheating system (110) is located upstream of the heating furnace (130) and includes one or more laser heating heads (111).

13. The heating system according to claim 11, wherein the laser heating head (111) is a multi-axis laser heating head.

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

15. The heating system of claim 13, wherein the preheating system includes a second laser heating head disposed downstream of the first laser heating head, the second laser heating head being movable in a direction perpendicular to the conveying direction of the slab.

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