Vehicle floor panel reinforcement

Abstract

The floor panel (3) is attached to the floor panel (3) and includes at least a front longitudinal portion (11) extending substantially longitudinally from the dash panel (4) to a transition portion (31) and defining, together with said floor panel (3), a front longitudinal hollow volume (10); a front lateral portion (21) extending substantially laterally between the left and right side sills (61, 62) of the vehicle, forming a front lateral hollow volume (20) together with the floor panel (3) and connected to the front longitudinal portion (11) at a transition portion (31); Equipped with The floor panel reinforcing member (1) is manufactured by forming a single metal blank (7), A floor panel reinforcement member (1) for an automobile (100).

Description

[Technical field]

[0001] The present invention relates to a structural part for an automobile, and more particularly to a reinforcing structure for a floor panel of a vehicle. [Background technology]

[0002] Automotive manufacturers are faced with increasingly demanding requirements to increase the passive safety of vehicles, lower vehicle weight to minimize greenhouse gas emissions in the case of internal combustion engines, and increase vehicle range in the case of electric vehicles, while keeping production costs low and production rates high.

[0003] The floor panel reinforcement member forms an important structural component of the vehicle and contributes to the safety of the occupants in the event of a frontal or side impact. The floor panel reinforcement member also plays an important role in protecting the battery pack or high voltage battery and its housing (HV battery housing) in the case of an electric or hybrid vehicle, and the hydrogen tank in the case of a fuel cell. In fact, these elements are generally located below the floor panel. When the vehicle is subjected to a frontal impact, the vertical elements of the floor panel reinforcement member pick up the impact energy transmitted by the frontal impact management system and act to further absorb a part of the impact energy and prevent intrusion into the passenger compartment. Similarly, the lateral elements of the floor panel reinforcement member pick up the impact energy transmitted by the side sill and act to absorb the energy and prevent intrusion. The floor panel reinforcement member also plays an important role in ensuring the rigidity of the entire vehicle body.

[0004] The floor panel reinforcement member contributes to improving the safety performance of the vehicle in various regulatory tests, such as:

[0005] -64, Insurance Institute for Highway Safety (IIHS) Small Overlap Rigid Barrier (SORB) crash in which a vehicle is struck by a rigid barrier moving at 4km / h with an overlap width of only 25%.

[0006] -64, IIHS Frontal Overlap Deformable Barrier (ODB), in which a vehicle is struck by a rigid barrier moving at 4km / h with an overlap width of only 25%.

[0007] -The United States New Car Assessment Program (USNCAP) pole test, in which a vehicle with an initial lateral speed of 32.2 km / h crashes into a fixed pole on its side.

[0008] - The IIHS Modular Deformable Barrier (MDB) test, in which a vehicle is struck on its side by a deformable barrier weighing 1500 kg and travelling at a speed of 50 km / h. Summary of the Invention [Problem to be solved by the invention]

[0009] It is an object of the present invention to provide a floor panel reinforcement member having a very high crash management efficiency. It is also an object of the present invention to provide a vehicle with a floor panel reinforcement member according to the present invention.

[0010] It is also an object of the present invention to provide a floor panel reinforcement member that is lighter than current designs, thereby saving fuel in the case of combustion engines and increasing driving range in the case of electric engine powered vehicles.

[0011] Furthermore, the objective of the present invention is to address the challenges of increasing productivity, reducing complexity, and reducing costs in vehicle production. Indeed, the present invention provides a floor panel reinforcement member with fewer parts than the reference design. The design of the present invention can be produced and assembled with significantly fewer manufacturing steps compared to the references. In addition to simplifying production, reducing the number of production steps reduces the environmental footprint of the production process as well as the overall CO2 emissions when manufacturing a vehicle.

[0012] The object of the present invention is achieved by providing a front member assembly as claimed in claim 1, comprising the features of claims 2 to 6, optionally taken individually or according to any conceivable combination. A further object of the present invention is achieved by providing a motor vehicle as claimed in claim 7. [Means for solving the problem]

[0013] In the following description and in the claims, directional terms are defined according to normal directions of the on-board vehicle.

[0014] In particular, terms such as "top", "up", "upper", "above", "bottom", "low", "lower", "below" are defined according to the height direction of the vehicle. Terms such as "front", "back", "rear", "front", "forward", "backward" are defined according to the longitudinal direction of the vehicle, i.e. the direction in which the vehicle moves when following a straight line. Terms such as "left", "right", "transverse" are defined according to an orientation parallel to the width of the vehicle. The terms "inner" and "outer" are to be understood according to the width direction of the vehicle, with "inner" being closest to the central axis of the vehicle, i.e. closest to the inside of the vehicle, while "outer" is located further away from said central axis of the vehicle and is in fact closer to the outside of the vehicle. The same applies to the terms "distal" and "central," with the "distal" portion being closest to the outside of the vehicle and the "central" portion being closest to the center of the vehicle. The term "horizontal" refers to a planar orientation including lengthwise and widthwise. The term "vertical" refers to any orientation including height.

[0015] In the following figures, all orientation and spatial references are provided using the X, Y, Z coordinates of reference, where Z is the height of the vehicle, X is the longitudinal direction of the vehicle, and Y is the transverse direction of the vehicle. References are represented on each figure. If the figure is a 2D flat display, the axis that is outside the figure is represented by a dot in a circle when it is pointing towards the reader, and a cross in a circle when it is pointing away from the reader, following established convention.

[0016] By "substantially parallel" or "substantially perpendicular" is meant that the direction may deviate from the parallel or perpendicular directions by no more than 15°.

[0017] Steel plate refers to a flat steel plate. The steel plate has a top surface and a bottom surface, also called top side and bottom side or top surface and bottom surface. The distance between said surfaces is specified as the thickness of the plate. The thickness can be measured, for example, using a micrometer, the spindle and anvil of which are placed on the top surface and bottom surface. Similarly, the thickness can also be measured on a molded part.

[0018] By average thickness of a part or portion of a part, it is meant the overall average thickness of the material that makes up the part after it has been initially formed from a flat sheet into a three-dimensional part.

[0019] A tailored blank is formed by assembling together several sheets or cut blanks of steel known as sub-blanks, e.g., by laser welding, to optimize the performance of the part in its different regions, reduce the overall part weight, and reduce the overall part cost. The sub-blanks forming the tailored blank can be assembled with or without overlap, e.g., the sub-blanks forming the tailored blank can be laser butt welded (no overlap) or the sub-blanks forming the tailored blank can be spot welded together (with overlap).

[0020] Unlike a tailored blank, a monolithic blank refers to a blank that consists of a single sub-blank, without several sub-blanks being combined with one another.

[0021] Tailor rolled blanks are blanks with multiple plate thicknesses obtained by differential rolling during the steel plate production process.

[0022] Ultimate tensile strength, yield strength, and elongation are measured according to ISO standard ISO 6892-1 published in October 2009. Tensile specimens are cut from the flat areas. If necessary, smaller tensile test samples are taken to cover the entire available flat area on the part.

[0023] The bending angle is measured according to the VDA-238 bending standard. For the same material, the bending angle depends on the thickness. For simplicity, the bending angle value of the present invention refers to a thickness of 1.5 mm. If the thickness is different from 1.5 mm, the bending angle value should be normalized to 1.5 mm by the following calculation, where α1.5 is the bending angle normalized at 1.5 mm, t is the thickness, and αt is the bending angle with respect to the thickness t.

[0024] α1.5=(αt×√t) / √1.5

[0025] Hot stamping is a forming technique in steel which involves heating a steel blank, or a preform made from a steel blank, to a temperature at which the microstructure of the steel is at least partially transformed into austenite, forming the blank or preform at high temperature by stamping, and simultaneously quenching the formed part to obtain a microstructure with very high strength, possibly with an additional distribution or tempering step in the heat treatment.

[0026] A multi-step hot stamping process is a specific type of hot stamping process consisting of at least two process steps, including at least one stamping step, performed at high temperatures above 300°C. For example, a multi-step process can include a first stamping step and a subsequent hot trimming step, so that there is no need to further trim the finished part at the end of the hot stamping process. For example, a multi-step process can involve several successive stamping steps to produce a part having a more complex shape than can be realized using a single stamping step. For example, the part is automatically transferred from one step to another in a multi-step process, for example using a transfer press. For example, the part remains in the same tool, which is a multi-purpose tool that can perform different steps, such as the first stamping and a subsequent in-tool trimming step.

[0027] The term "bottling" refers to a deformation mode of a part, typically a highly elongated part, subjected to a compressive load, in which the part gradually absorbs the mechanical energy of the compressive load by forming a series of successive waves resulting from successive local buckling deformations of the part. As a result, the length of the part measured in the direction of the compressive load is less than the initial length of the part in said direction after deformation. In other words, when a part reacts to a compressive load by controlled buckling, the part folds over on itself in the same way as a plastic bottle when a compressive load is applied between the top and bottom ends of the bottle. [Brief description of the drawings]

[0028] [Figure 1] 1 is a perspective view of an automobile having a floor panel reinforcing member according to the present invention; [Diagram 2] 1 is a perspective view of a first embodiment of a floor panel reinforcing member according to the present invention. [Diagram 3] 1 is a perspective view of a second embodiment of a floor panel reinforcing member according to the present invention. FIG. [Figure 4] 13 is a perspective view of a third embodiment of a floor panel reinforcing member according to the present invention. FIG. [Diagram 5] FIG. 11 is a perspective view of a fourth embodiment of a floor panel reinforcing member according to the present invention. [Figure 6] FIG. 11 is a perspective view of a fifth embodiment of a floor panel reinforcing member according to the present invention. [Figure 7] 1 is a perspective view of a metal blank used to manufacture a floor panel reinforcement member according to the present invention; FIG. [Figure 8A] 2 is a top view of the floor panel reinforcing member according to the first embodiment shown in FIG. 1. [Figure 8B] FIG. 8B is a cross-sectional view taken along axis AA defined in FIG. 8A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Compared to the original computer-aided design of the floor panel reinforcement member used in relation to the first embodiment, the cross section of FIG. 20 It should be noted that the height of the image has been exaggerated to better represent the height of the image.

[0030] 2-6, for clarity, the floor panel reinforcement member is shown separately without showing the surrounding vehicle components, however, in the following description, the floor panel reinforcement member of the figures will be described as assembled within the vehicle structure.

[0031] With reference to Figure 1, the passenger compartment 101 of a motor vehicle 100 is the volume accessible to vehicle occupants. For obvious safety reasons, said passenger compartment 101 needs to be protected in the event of a crash. The lower part of the passenger compartment is defined by a floor panel 3 that extends longitudinally from a dash panel 4 at the front to a heel board 5 at the rear. The floor panel 3 further extends transversely between left and right side sills 61, 62. In the case of an electric vehicle, the HV battery housing is typically located below the floor panel 3.

[0032] The floor panel reinforcing member 1 according to the present invention is positioned on said floor panel 3 and has a sidewall that extends at least in a height direction from a base height corresponding to the height of the floor panel 3 to a higher height above the floor panel 3. By the sidewall extending at least in a height direction, it is meant that the direction in which the sidewall extends comprises at least a height component, but may also comprise a vertical and / or horizontal component. In other words, the sidewall extends in a height direction, possibly at an angle towards the height direction.

[0033] The floor panel reinforcing member 1 extends vertically from the dash panel 4 toward the rear of the vehicle. In the horizontal direction, the floor panel reinforcing member 1 extends between the left and right side sills 61, 62. As will be described later, according to certain embodiments, the floor panel reinforcing member 1 can extend vertically toward the rear of the vehicle up to the heel board 5, or can extend vertically only to a point located in front of the heel board 5. In contrast, the floor reinforcing structure 1 according to the present invention always extends horizontally between the left and right side sills 61, 62.

[0034] 2, the floor panel reinforcing member 1 according to the present invention comprises at least a front vertical portion 11, a front lateral portion 21 and a front transition portion 31. When assembled in a vehicle, the front lateral portion 11 extends substantially vertically from the dash panel 4 to the front transition portion 31. When assembled in a vehicle, the front lateral portion 21 extends substantially horizontally between the left and right side sills 61, 62. The front transition portion 31 ensures an orientation transition between the substantially vertically extending front vertical portion 11 and the substantially horizontally extending front lateral portion 21. To this end, the side walls of the front transition portion 31 are curved.

[0035] 2 and 8A, the curvature of the sidewall of transition section 31 is measured by radii of curvature R1, R2 for the left and right sidewalls, respectively. The radii of curvature R1, R2 are defined as the radii of a circle whose arc is closest to the curved shape of the sidewall of transition section 31. The circle is shown in FIG. 8A, where reference characters C1, C2 correspond to the left and right radii of curvature R1, R2, respectively.

[0036] When assembled in the vehicle, the floor panel reinforcement member 1 is attached to at least the floor panel 3, for example by spot welding to the flanges or by laser welding to the flanges, for example by remote laser welding or remote laser stitch welding. In a particular embodiment, the floor panel reinforcement member 1 is further attached to the dash panel 4. Thanks to the fact that the side walls extend at least in the height direction, the assembled floor panel reinforcement member 1 together with the floor panel 3 forms a front vertical hollow volume 10 in the vertical direction and a front lateral hollow volume 20 in the lateral direction. The front vertical hollow volume 10 extends substantially vertically from the dash panel 4 to the front transition portion 31. The lateral hollow volume 20 extends substantially laterally between the left and right side sills 61, 62. The front vertical and lateral hollow volumes 10, 20 are connected in the front transition portion 31.

[0037] Said front longitudinal and transverse hollow volumes 10, 20 are important in withstanding and absorbing crash energy and in increasing the rigidity of the entire vehicle. Indeed, thanks to the presence of hollow volumes, the overall inertia and therefore the structural resistance of the vehicle can be guaranteed.

[0038] The floor panel reinforcement member according to the invention is manufactured by forming a single metal blank into the desired shape of the final part, for example by stamping said metal blank, for example the stamping process being a hot stamping process or a multi-stage hot stamping process.

[0039] An example of such a single metal blank 7 is represented in figure 7. This metal blank corresponds to the blank used to manufacture the floor panel reinforcement member 1 of figure 3.

[0040] For example, the unitary metal blank is a laser welded blank formed from several sub-blanks joined together by laser butt welds or joined together by spot welds or a combination of both. For example, the unitary metal blank is a tailor rolled blank.

[0041] Thanks to the fact that the floor panel reinforcement member is formed from a single metal sheet, the manufacturing process is significantly simplified compared to conventional designs in which several parts are formed from several different blanks and then assembled together. This simplification leads to increased productivity and reduced costs during vehicle manufacturing. Thanks to the reduced complexity in logistics and manufacturing, this simplification can also contribute to reduced CO2 emissions during vehicle manufacturing.

[0042] A further advantage of incorporating longitudinal and transverse elements in one single part made from one single blank is the absence of assembly points that could result in structural weaknesses. Indeed, since the part is a single upright element, it does not contain assembly points between different sub-parts that are potential structural weaknesses. For example, if the individual parts of a conventional multi-part design are welded together, the heat-affected zone or weld nugget created by the welding process itself can be a structural weak point of the assembly, which leads to failure in case of a crash or due to fatigue stresses or other causes. Furthermore, the absence of assembly points also allows optimal structural cooperation between the different elements of the reinforcement structure. For example, when the part is subjected to longitudinal stresses in case of a frontal crash, the front longitudinal part 11 is largely involved in resisting and absorbing the crash energy, but it can also rely on the front transverse part 21 to resist and absorb part of the crash energy and also divert said crash energy laterally in order to resist and involve as much of the vehicle structure as possible in absorbing the crash energy.

[0043] Furthermore, the absence of assembly points between the several individual parts contributes to the overall weight reduction: indeed, to assemble the several parts together, overlapping areas are required where two thicknesses of metal overlap each other, which results in an increase in weight compared to the integrated design.

[0044] In a particular embodiment as shown in Figure 2, the front longitudinal portion 11 comprises a front longitudinal rib 12 located on said longitudinal portion. Said rib 12 increases the stiffness of said front longitudinal portion 11 and therefore its crashworthiness and stiffness performance.

[0045] In a particular embodiment as shown in Figure 2, the front lateral portion 21 comprises a front longitudinal rib 22 located on said longitudinal portion. Said rib 22 increases the stiffness of said front longitudinal portion 21 and therefore its crashworthiness and stiffness performance.

[0046] In certain embodiments, certain ratio limits are set between the sidewall radius of curvature of the transition portion 31 and the height of the sidewall of the transition portion 31. More precisely, with reference to Figures 8A and 8B, H1 and H2 are the heights of the left and right sidewalls of the transition portion 31, respectively, at the points where the sidewalls make an angle of 20° with the lateral direction. In Figures 8A and 8B, the points where the left and right sidewalls make an angle of 20° with the lateral direction are indicated by A1 and A2, respectively.

[0047] For example, as shown in FIG. 3, if there are several separate front longitudinal portions 11 in the design of the floor panel reinforcement member, and therefore several front transition portions 31, the contribution of each of these transition portions 31 in the aforementioned ratio must be taken into account.

[0048] The number n of the front vertical portions 11 is an integer equal to or greater than 1, counting the number of separate front vertical portions 11 in the floor panel reinforcement member. For example, in FIG. 2 n=1, but in FIG. 3 n=2.

[0049] In certain embodiments, the product of the ratio of the sum of the radii of curvature R1, R2 of the side walls of the transition portion to the sum of the heights H1, H2 of the side walls of the transition portion and the number n of distinct front longitudinal portions 11 is at least equal to 4. This can be expressed by the following formula:

[0050]

number

[0051] The inventors have found that by ensuring a minimum ratio between the sidewall curvature in the transition section and the sidewall height of the transition section close to the lateral section, the crash performance, especially the side impact crashworthiness, is improved. Indeed, when faced with a side impact, the sidewalls of the front lateral section act to absorb and resist compressive crash loads. The curvature of the sidewalls of the transition section 31 potentially represents a weakness towards said compressive loads where stress concentrations may result in collapse. The inventors have found that by ensuring the aforementioned ratio, it is possible to ensure very good lateral dynamic load characteristics for the floor panel reinforcement member.

[0052] For example, the inventors have found that very good side impact behavior can be obtained by using the following floor panel reinforcement members:

[0053] [Table 1]

[0054] In a particular embodiment, the front longitudinal portion 11 further comprises a deformable portion extending over the front of said front longitudinal portion 11 and a non-deformable portion extending over the rear of said portion 11. The resistance of said deformable portion to plastic deformation is lower than the resistance of said non-deformable portion to plastic deformation. For example, the product of the average thickness and tensile strength of said deformable portion is lower than the product of the tensile strength by the average thickness of said non-deformable portion. Advantageously, in the case of a frontal impact, this allows to manufacture a floor panel reinforcement member 1 having a front portion corresponding to the deformable portion, which undergoes plastic deformation, for example by bottling, and thus absorbs part of the collision energy. At the same time, the non-deformable portion located at the rear and therefore closest to the vehicle occupant resists intrusion and thus protects the occupant and the HV battery housing, while transmitting the remaining energy of the impact to the rest of the vehicle structure.

[0055] In a particular embodiment, the front lateral portion 21 further comprises a deformable portion extending over a distal portion of said front lateral portion and a non-deformable portion extending over a central portion of said portion. In a particular embodiment, the deformable portions are located on both sides of the front lateral portion. The resistance to plastic deformation of said deformable portions is lower than the resistance to plastic deformation of said non-deformable portions. For example, the product of the average thickness and tensile strength of said deformable portions is lower than the product of the tensile strength by the average thickness of said non-deformable portions. Advantageously, in case of a side impact, this allows to manufacture a floor panel reinforcement member 1 having a distal portion corresponding to the deformable portion, which undergoes plastic deformation, for example by bottling, and thus absorbs part of the crash energy. At the same time, the non-deformable portion located towards the center and therefore closest to the vehicle occupant resists intrusion and thus protects the occupant and the HV battery housing, while transmitting the remaining energy of the impact to the rest of the vehicle structure.

[0056] In certain embodiments, the aforementioned deformable and non-deformable portions are obtained by manufacturing the floor panel reinforcement member using a laser-welded blank comprising a material that has a lower resistance to plastic deformation after being formed into the deformable portion than in the non-deformable portion.

[0057] In the particular embodiment shown in Figure 2, the floor panel reinforcement member 1 consists only of a front longitudinal portion 11 and a front lateral portion 21. For example, the front longitudinal portion is centrally located, e.g., aligned with the center of the dash panel 4. For example, the front longitudinal portion replaces what is commonly known as a tunnel reinforcement. For example, the front lateral portion replaces a front seat floor cross member.

[0058] In the particular embodiment shown in Figure 3, the floor panel reinforcement member 1 consists only of two front longitudinal portions 11 and a front lateral portion 21. For example, the front longitudinal portion is positioned towards the side of the floor panel reinforcement that is aligned with the front longitudinal member, for example located at the front end of the vehicle (not shown).

[0059] In the particular embodiment shown in Figure 3, the floor panel reinforcement member 1 comprises two front longitudinal portions 11 and one front transverse portion 21. For example, the front longitudinal portions are positioned towards the side of the floor panel reinforcement that is aligned with the front longitudinal members, for example, positioned at the front end of the vehicle (not shown).

[0060] In the particular embodiment shown in Figures 3 and 4, the floor panel reinforcement member 1 comprises a front transverse portion 21 and at least one further transverse portion 22, which extends substantially transversely between the side sills 61, 62 and has side walls extending at least in height such that said further transverse portion 22 forms a further transverse hollow volume together with the floor panel 3. Advantageously, this allows further integration of transverse cross members into the floor panel reinforcement member, further exploiting the advantages of simplified production and structural optimization mentioned above.

[0061] In a particular embodiment, the floor panel reinforcing member 1 comprises a further lateral portion 22 with a deformable portion extending over a distal portion of said further lateral portion and a non-deformable portion extending over a central portion of said portion. In a particular embodiment, the deformable portions are located on both sides of the further lateral portion. The resistance to plastic deformation of said deformable portions is lower than the resistance to plastic deformation of said non-deformable portions. For example, the product of the average thickness and tensile strength of said deformable portions is lower than the product of the tensile strength by the average thickness of said non-deformable portions. Advantageously, in case of a side impact, this allows to manufacture a floor panel reinforcing member 1 with a distal portion corresponding to the deformable portion, which undergoes plastic deformation, for example by bottling, and thus absorbs part of the impact energy. At the same time, the non-deformable portion located towards the center and therefore closest to the vehicle occupant resists intrusion and thus protects the occupant and the HV battery housing, while transmitting the remaining energy of the impact to the rest of the vehicle structure. When this embodiment is combined with the previously described embodiment in which the front lateral portion 21 also comprises a distal portion having a deformable portion, the deformable portion of the front lateral portion 21 and the one or more further lateral portions 22 can cooperate to absorb energy together in the event of a side impact, while the non-deformable portions cooperate to resist intrusion.

[0062] In the particular embodiment shown in Figure 3, the further transverse portion 22 is attached to the floor panel reinforcement member by lateral intermediate portions 23 that extend substantially longitudinally between the sides of the transverse portions. This design allows the floor panel reinforcement member to be easily incorporated into the vehicle assembly and gives a very good overall structural stability to the floor panel reinforcement member 1. The presence of the two lateral intermediate portions 23 further increases the strength of the floor panel assembly and its overall contribution to the stiffness of the vehicle body.

[0063] In the particular embodiment shown in Fig. 4, the further transverse portion 22 is attached to the floor panel reinforcement by a central intermediate portion 24. Said central intermediate portion 34, for example, comprises a side wall extending at least in height and forming a further vertical hollow volume together with the floor panel 3. Advantageously, this allows to extend the load path of the front longitudinal portion, thereby increasing the resistance to frontal impacts, and also thereby improving the overall stiffness performance of the vehicle.

[0064] In the particular embodiment shown in Figure 5, the floor panel reinforcement member comprises two further lateral portions 22, each attached to the floor panel reinforcement member 1 by a central intermediate portion 24. In the embodiment shown in Figure 5, the floor panel reinforcement member 1 further comprises a heel board 5. This design allows for very large floor panel reinforcement members, thus providing further benefits of the aforementioned benefits of component integration.

[0065] In the particular embodiment shown in Figure 6, the floor panel reinforcement member comprises two further lateral parts 22 which are attached directly to each other and to the front lateral part 21. This allows for a very robust, compact, resistant and stiff design.

[0066] In the particular embodiment shown in Figure 7, the metal blank 7 used to manufacture the floor panel reinforcement member 1 further comprises a patch 8 in order to locally increase the thickness of the part and therefore the structural resistance. The patch is manufactured by locally attaching a smaller metal blank onto the initial metal blank, for example by spot welding or by laser welding.

[0067] In a particular embodiment, the floor panel reinforcement member is formed by hot stamping and the blank used to produce it comprises one of the following materials, combined in the form of a monolithic blank or in the form of a tailored blank:

[0068] - A steel having a composition, in weight percent, of 0.06%≦C≦0.1%, 1%≦Mn≦2%, Si≦0.5%, AI≦0.1%, 0.02%≦Cr≦0.1%, 0.02%≦Nb≦0.1%, 0.0003%≦B≦0.01%, N≦0.01%, S≦0.003%, P≦0.020%, less than 0.1% Cu, Ni and Mo, the remainder being iron and unavoidable impurities resulting from refining. In this composition range, the yield strength of the corresponding area after hot stamping is comprised between 700 and 950 MPa, the tensile strength is comprised between 950 MPa and 1200 MPa, and the bending angle is greater than 75°. For example, this material is used for deformable parts of floor panel reinforcement elements, since its high bending angle combined with high mechanical properties allows it to absorb large amounts of crash energy, for example by bottling.

[0069] Steels having an ultimate tensile strength after hot stamping comprised between -1300 MPa and 1650 MPa and a yield strength comprised between 950 MPa and 1250 MPa.

[0070] - Steels having an ultimate tensile strength after hot stamping comprised between 1300 MPa and 1650 MPa, a yield strength comprised between 950 MPa and 1250 MPa, and a bending angle of more than 75°.

[0071] - a steel with a composition comprising, in weight percent, 0.20%≦C≦0.25%, 1.1%≦Mn≦1.4%, 0.15%≦Si≦0.35%, Cr≦0.30%, 0.020%≦Ti≦0.060%, 0.020%≦Al≦0.060%, S≦0.005%, P≦0.025%, 0.002%≦B≦0.004%, the remainder being iron and unavoidable impurities resulting from refining. In this composition range, the maximum tensile strength of the corresponding area of ​​the part after hot stamping is comprised between 1300 MPa and 1650 MPa, and the yield strength is comprised between 950 MPa and 1250 MPa. For example, this steel composition is used for the non-deformed parts of floor panel reinforcement elements, since thanks to its high mechanical properties it allows to withstand penetrations.

[0072] - Steel with a tensile strength after press hardening higher than 1800 MPa.

[0073] - a steel with the composition, in weight percent, of 0.24%≦C≦0.38%, 0.40%≦Mn≦3%, 0.10%≦Si≦0.70%, 0.015%≦Al≦0.070%, Cr≦2%, 0.25%≦Ni≦2%, 0.015%≦Ti≦0.10%, Nb≦0.060%, 0.0005%≦B≦0.0040%, 0.003%≦N≦0.010%, S≦0.005%, P≦0.025%, and the remainder being iron and unavoidable impurities resulting from refining. In this composition range, the tensile strength of the corresponding area of ​​the front component assembly after hot stamping is higher than 1800 MPa. This material is used, for example, in the non-deformed parts.

[0074] a steel having a composition comprising, in weight percent, C: 0.15-0.25%, Mn: 0.5-1.8%, Si: 0.1-1.25%, Al: 0.01-0.1%, Cr: 0.1-1.0%, Ti: 0.01-0.1%, B: 0.001-0.004%, P≦0.020%, S≦0.010%, N≦0.010%, and optionally one or more of the following elements in weight percent: Mo≦0.40%, Nb≦0.08%, Ca≦0.1%, with the remainder of the composition being iron and unavoidable impurities resulting from smelting, in which the tensile strength of the corresponding area of ​​the floor panel reinforcement member after hot stamping is higher than 1350 MPa and the bending angle is higher than 70°;

[0075] a steel having a composition comprising, in weight percent, C: 0.26-0.40%, Mn: 0.5-1.8%, Si: 0.1-1.25%, Al: 0.01-0.1%, Cr: 0.1-1.0%, Ti: 0.01-0.1%, B: 0.001-0.004%, P≦0.020%, S≦0.010%, N≦0.010%, and optionally one or more of the following elements in weight percent: Ni≦0.5%, Mo≦0.40%, Nb≦0.08%, Ca≦0.1%, with the remainder of the composition being iron and unavoidable impurities resulting from smelting, in which the tensile strength of the corresponding area of ​​the floor panel reinforcement after hot stamping is higher than 1500 MPa and the bending angle is higher than 70°;

[0076] a steel having a composition comprising, in weight percent, C: 0.2-0.34%, Mn: 0.50-1.24%, Si: 0.5-2%, P≦0.020%, S≦0.010%, N≦0.010%, and optionally one or more of the following elements in weight percent: Al:≦0.2%, Cr≦0.8%, Nb≦0.06%, Ti≦0.06%, B≦0.005%, Mo≦0.35%, with the remainder of the composition being iron and unavoidable impurities resulting from smelting, in which the tensile strength of the corresponding area of ​​the floor panel reinforcement member after hot stamping is 1000 MPa or more and the bending angle is greater than 55°;

[0077] - Steel containing, in weight percent, C: 0.13-0.4%, Mn: 0.4-4.2%, Si: 0.1-2.5%, Cr≦2%, Mo≦0.65%, Nb≦0.1%, Al≦3.0%, Ti≦0.1%, B≦0.005%, P≦0.025%, S≦0.01%, N≦0.01%, Ni≦2.0%, Ca≦0.1%, W≦0.30%, V≦0.1%, Cu≦0.2% and verifying the following combination: 114-68*C-18*Mn+20*Si-56*Cr-60*Ni-36*Al+38*Mo+79*Nb-17691*B<20, with the remainder of the composition being iron and unavoidable impurities resulting from smelting. For example, this composition is used when hot stamping parts using a multi-step process.

[0078] - Steel coated with an aluminium-based metallic coating. Aluminium-based means a coating containing at least 50% aluminium by weight. For example, the metallic coating is an aluminium-based coating containing 8-12% Si by weight. The metallic coating is applied, for example, by immersing the substrate in a molten metal bath. Advantageously, the application of the aluminium-based metallic coating avoids the formation of surface scales during the heating step of the hot stamping process, thereby making it possible to produce parts by hot stamping without a subsequent sandblasting step. Furthermore, the aluminium-based coating also provides corrosion protection to the part during use in the vehicle.

[0079] - a steel coated with an aluminium-based metallic coating comprising 2.0-24.0% by weight of zinc, 1.1-12.0% by weight of silicon, optionally 0-8.0% by weight (by weight) of magnesium and optionally a further element selected from Pb, Ni, Zr or Hf, the content by weight of each further element being lower than 0.3% by weight, the remainder being aluminium and optionally unavoidable impurities. Advantageously, this type of metallic coating gives very good corrosion protection on the part as well as good surface morphology after hot stamping.

[0080] In a particular embodiment, at least the upper or lower shell is formed by hot stamping a laser-welded blank comprising at least one sub-blank with an aluminum-based metal coating, said aluminum-coated sub-blank being pre-prepared by ablating at least a portion of the metal coating on the edges to be welded, preferably removing a portion of the aluminum present in the coating that would contaminate the weld seam and reduce its mechanical properties.

[0081] In a particular embodiment, the floor panel reinforcement member is formed by hot stamping a laser-welded blank comprising at least one sub-blank having at least one side covered with an emissivity-enhancing top layer. The emissivity-enhancing top layer is applied to the outermost surface of the sub-blank. The emissivity-enhancing top layer allows the surface of the sub-blank to have a higher emissivity compared to the same sub-blank not coated with the emissivity-enhancing top layer. The emissivity-enhancing top layer can be applied to either the top or bottom surface of the sub-blank. The emissivity-enhancing top layer can also be applied to both sides of the sub-blank. If the sub-blank comprises a metal coating as described above, the emissivity-enhancing top layer is applied on the metal coating. In fact, the emissivity-enhancing top layer needs to cover the outermost surface of the sub-blank to increase the emissivity of the surface. Advantageously, the emissivity-enhancing top layer allows the heating rate of the sub-blank to be increased, and therefore the productivity of the heating step of the hot stamping process to be increased. When using several sub-blanks of different thicknesses, said emissivity-enhancing top layer is preferably applied to the sub-blank with the highest thickness in order to reduce the difference in heating times between the different sub-blanks and thus increase productivity, increase the hot stamping process window and make it possible to obtain a final part with generally uniform surface properties.

Claims

1. A floor panel reinforcing member (1) for an automobile (100) that is attached to a floor panel (3) and has at least a front longitudinal portion (11), a front lateral portion (21), and a front transition portion (31), - the front longitudinal portion (11), the front lateral portion (21) and the front transition portion (31) each comprise at least left and right side walls extending at least in height from the floor panel (3) to a height higher than the floor panel (3); - said front longitudinal portion (11) extends substantially longitudinally from the dash panel (4) to said front transition portion (31) and defines, together with said floor panel (3), a front longitudinal hollow volume (10); said front transverse portion (21) extends substantially laterally between the left and right side sills (61, 62) of the vehicle, forming a front transverse hollow volume (20) together with said floor panel (3) and being connected to said front longitudinal portion (11) at a front transition portion (31); It is as follows. The floor panel reinforcement member (1) is manufactured by forming a single metal blank (7), A floor panel reinforcement member (1) for an automobile (100).

2. A floor panel reinforcement (1) for a motor vehicle (100) according to claim 1, wherein the single metal blank (7) is a laser welded blank comprising several sub-blanks.

3. 3. A floor panel reinforcement element (1) for a motor vehicle (100) according to claim 1 or 2, wherein the floor panel reinforcement element (1) is manufactured by hot stamping the single metal blank (7).

4. - comprising n distinct front longitudinal portions (11) and associated front transition portions (31), n ​​being an integer greater than or equal to 1; - for each front transition portion (31) it comprises left and right side walls having radii of curvature R1, R2 and heights H1, H2 respectively defined as the heights of the left and right side walls of said transition portion in the height direction at the points where said side walls make an angle of 20° with the transverse direction, the product of the ratio of the sum of the radii of curvature R1, R2 of the side walls of the front transition portion to the sum of the heights H1, H2 of the side walls of the front transition portion and n is at least equal to 4; [0010] A floor panel reinforcing member (1) according to any one of claims 1 to 3.

5. A floor panel reinforcing member (1) as described in any one of claims 1 to 4, further comprising at least one further lateral portion (22) extending substantially laterally between the side sills (61, 62) and having a side wall, the side wall extending at least in the height direction so that the at least one further lateral portion (22) forms a further lateral hollow volume together with the floor panel (3), the at least one further lateral portion (22) being attached to the floor panel reinforcing member by a lateral intermediate portion (23) extending substantially vertically between the side surfaces of the lateral portions (21, 22).

6. A floor panel reinforcement member (1) as described in any one of claims 1 to 4, further comprising at least one further lateral portion (22) extending substantially laterally between the side sills (61, 62) and having a side wall, the side wall extending at least in the height direction such that the at least one further lateral portion (22) forms a further lateral hollow volume together with the floor panel (3), the at least one further lateral portion (22) being attached to the floor panel reinforcement member by a central intermediate portion (24).

7. A motor vehicle (100) comprising a floor panel reinforcing member (1) according to any one of claims 1 to 6.

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