Vehicle floor panel reinforcing member

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 component for an automobile, and more particularly to a reinforcement structure for a floor panel of a vehicle.

Background Art

[0002] Automobile manufacturers are increasingly faced with stringent requirements of reducing vehicle weight to enhance the passive safety of vehicles and minimize greenhouse gas emissions in the case of internal combustion engines or increasing the driving range of vehicles in the case of electric vehicles, while keeping production costs low and maintaining high production speed.

[0003] Floor panel reinforcement members form an important structural component of an automobile and contribute to the safety of passengers in the case of a frontal collision or a side collision. Also, floor panel reinforcement members play an important role in protecting the battery pack or high-voltage battery and its housing (HV battery housing) in the case of an electric vehicle or a hybrid vehicle, and a hydrogen tank in the case of a fuel cell vehicle. In fact, these elements are generally located below the floor panel. When the vehicle is subjected to a frontal collision, the longitudinal elements of the floor panel reinforcement member pick up the impact energy transmitted by the frontal collision management system, further absorb a part of the collision energy, and act to 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. Also, the floor panel reinforcement member plays an important role in ensuring the rigidity of the entire vehicle body.

[0004] Floor panel reinforcement members are involved in improving the safety performance of vehicles in various regulatory tests such as the following.

[0005] - The Small Overlap Rigid Barrier (SORB) collision of the Insurance Institute for Highway Safety (IIHS) in which the vehicle collides with a rigid barrier moving at 64.4 km / h with an overlap of only 25% of the width.

[0006] IIHS Frontal Overlap Deformable Barrier (ODB), in which a vehicle is struck by a rigid barrier moving at -64.4 km / h with only a 25% width overlap.

[0007] - The US New Car Assessment Programme (USNCAP) pole test involves a vehicle with an initial lateral speed of 32.2 km / h colliding with a fixed pole on its side.

[0008] The IIHS side-movable deformable barrier (MDB) test involves a vehicle being struck on its side by a deformable barrier weighing -1500 kg and traveling at a speed of 50 km / h. [Overview of the project] [Problems that the invention aims to solve]

[0009] An object of the present invention is to provide a floor panel reinforcing member having extremely high collision management efficiency. Another object of the present invention is to provide a vehicle equipped with the floor panel reinforcing member according to the present invention.

[0010] Furthermore, an object of the present invention is to provide a floor panel reinforcing member that is lighter than current designs, thereby saving fuel in the case of combustion engines and extending the driving range in the case of electric engine-driven vehicles.

[0011] Furthermore, an objective of the present invention is to address the challenges of improving productivity, reducing complexity, and lowering costs in vehicle production. In fact, the present invention provides a floor panel reinforcement member having fewer parts than the reference design. The design of the present invention can be produced and assembled in significantly fewer manufacturing steps compared to the referenced literature. In addition to simplifying production, reducing the number of production steps reduces the environmental footprint of the production process and also reduces overall CO2 emissions when manufacturing vehicles.

[0012] An object of the present invention is achieved by providing the front member assembly according to claim 1, having features of claims 2 to 6 which are optionally interpreted individually or in any conceivable combination. A further object of the present invention is achieved by providing the automobile according to claim 7. [Means for solving the problem]

[0013] In the following description and claims, terms indicating direction shall be defined according to the normal direction of the vehicle on which it is mounted.

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

[0015] In the following diagrams, all orientation and spatial references are derived using the reference X, Y, and Z coordinates, where Z is the vehicle's height direction, X is the vehicle's longitudinal direction, and Y is the vehicle's lateral direction. The references are shown in each diagram. When a diagram is a 2D planar representation, axes outside the diagram are represented, according to established convention, by a dot in a circle when they are facing the reader, and by a cross in a circle when they are facing away from the reader.

[0016] "Substantially parallel" or "substantially perpendicular" means a direction that can deviate from the parallel or perpendicular direction by no more than 15°.

[0017] A steel plate refers to a flat steel plate. A steel plate has an upper end and a lower end, also called the upper surface and lower surface. The distance between these surfaces is specified as the plate thickness. For example, the thickness can be measured using a micrometer, with its spindle and anvil positioned on the upper and lower surfaces. Similarly, the thickness can also be measured on a molded part.

[0018] The average thickness of a part or a portion of a part refers to the overall average thickness of the material that makes up the part after it has been formed from a flat plate into a three-dimensional part.

[0019] Tailored blanks are formed by assembling several plates or cut blanks of steel, known as subblanks, together, for example by laser welding, to optimize the performance of the part in its different areas, reduce the overall part weight, and lower the overall part cost. The subblanks forming the tailored blank can be assembled with or without overlapping joints; for example, the subblanks forming the tailored blank can be laser butt-welded (without overlapping joints), or the subblanks forming the tailored blank can be spot-welded to each other (with overlapping joints).

[0020] Unlike tailored blanks, monolithic blanks refer to blanks consisting of a single sub-blank, without several sub-blanks being combined with each other.

[0021] A tailor-rolled blank is a blank with multiple thicknesses obtained by differential rolling during the steel sheet production process.

[0022] Ultimate tensile strength, yield strength, and elongation are measured according to ISO standard ISO 6892-1, published in October 2009. Tensile test specimens are cut from a flat area. 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 values ​​in this invention refer to a thickness of 1.5 mm. If the thickness is different from 1.5 mm, the bending angle value must be normalized to 1.5 mm by the following calculation, where α1.5 is the bending angle normalized to 1.5 mm, t is the thickness, and αt is the bending angle with respect to thickness t.

[0024] α1.5 = (αt × √t) / √1.5

[0025] Hot stamping is a steel forming technique that involves heating a steel blank, or a preform made from a steel blank, to a temperature at which the steel's microstructure is transformed at least partially into austenite; forming the blank or preform at a high temperature by stamping it; and simultaneously rapidly cooling the formed product to obtain a microstructure with very high strength, and may involve further distribution or tempering steps in the heat treatment.

[0026] The multi-stage hot stamping process is a specific type of hot stamping process that includes at least one stamping step and consists of at least two process steps carried out at a high temperature exceeding 300°C. For example, the multi-stage process can include a first stamping step and a subsequent hot trimming step, whereby there is no need to further trim the finished part at the end of the hot stamping process. For example, the multi-stage process can involve several consecutive stamping steps in order to manufacture parts having a more complex shape than can be achieved using a single stamping step. For example, the parts are automatically transferred from one process to another in the multi-stage process, for example using a transfer press. For example, the parts remain within the same tool, which is a multi-purpose tool capable of performing different processes such as an initial stamping and a subsequent in-tool trimming process.

[0027] The term "bottling" refers to the deformation mode of a part subjected to a compressive load, typically a highly elongated part, where the part gradually absorbs the mechanical energy of the compressive load by forming a series of continuous 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 shorter after deformation than the initial length of the part in said direction. In other words, when the part reacts to the compressive load by controlled buckling, the part folds over itself in the same way as a plastic bottle when a compressive load is applied between the upper and lower ends of the bottle.

Brief Description of the Drawings

[0028] [Figure 1] It is a perspective view of an automobile having a floor panel reinforcing member according to the present invention. [Figure 2] It is a perspective view of a first embodiment of a floor panel reinforcing member according to the present invention. [Figure 3] It is a perspective view of a second embodiment of a floor panel reinforcing member according to the present invention. [Figure 4] It is a perspective view of a third embodiment of a floor panel reinforcing member according to the present invention. [Figure 5] This is a perspective view of a fourth embodiment of the floor panel reinforcing member according to the present invention. [Figure 6] This is a perspective view of a fifth embodiment of the floor panel reinforcing member according to the present invention. [Figure 7] This is a perspective view of a metal blank used to manufacture a floor panel reinforcing member according to the present invention. [Figure 8A] Figure 1 is a top view of the floor panel reinforcing member according to the first embodiment. [Figure 8B] This is a cross-sectional view along axis AA as defined in Figure 8A. [Modes for carrying out the invention]

[0029] Compared to the original computer-aided design of the floor panel reinforcing member used in the first embodiment, the cross-section in Figure 8B shows the side wall H 20 It should be noted that the height has been exaggerated and made longer in the height direction to better represent the actual height.

[0030] In Figures 2 to 6, for clarity, the floor panel reinforcement members are shown individually without showing surrounding vehicle components. However, in the following description, the floor panel reinforcement members in the figures are shown assembled within the vehicle structure.

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

[0032] The floor panel reinforcing member 1 according to the present invention is positioned on the floor panel 3 and has a side wall that extends at least in the height direction from a base height corresponding to the height of the floor panel 3 to a higher height above the floor panel 3. The statement that the side wall extends at least in the height direction means that the direction in which the side wall extends includes at least a height component, but may also include vertical and / or horizontal components. In other words, the side wall extends in the height direction at an angle, possibly toward the height direction.

[0033] The floor panel reinforcing member 1 extends longitudinally from the dash panel 4 toward the rear of the vehicle. In the lateral direction, the floor panel reinforcing member 1 extends between the left and right side sills 61 and 62. As will be described later, according to a particular embodiment, the floor panel reinforcing member 1 can extend longitudinally toward the rear of the vehicle to the heel board 5, and can also extend longitudinally only to a point located in front of the heel board 5. On the other hand, the floor reinforcement structure 1 according to the present invention always extends laterally between the left and right side sills 61 and 62.

[0034] Referring to Figure 2, the floor panel reinforcing member 1 according to the present invention comprises at least a front longitudinal portion 11, a front transverse portion 21, and a front transition portion 31. When assembled in a vehicle, the front transverse portion 11 extends substantially longitudinally from the dash panel 4 to the front transition portion 31. When assembled in a vehicle, the front transverse portion 21 extends substantially transversely between the left and right side sills 61, 62. The front transition portion 31 ensures an orientation transition between the front longitudinal portion 11, which extends substantially longitudinally, and the front transverse portion 21, which extends substantially transversely. For this purpose, the side walls of the front transition portion 31 are curved.

[0035] Referring to Figures 2 and 8A, the curvature of the side walls of the transition section 31 is measured by the radii of curvature R1 and R2 for the left and right side walls, respectively. The radii of curvature R1 and R2 are defined as the radii of the circles whose arcs are closest to the curved shape of the side walls of the transition section 31. The circles are shown in Figure 8A, where reference numerals C1 and C2 correspond to the left and right radii of curvature R1 and R2, respectively.

[0036] Once installed in the vehicle, the floor panel reinforcement member 1 is attached to at least the floor panel 3 by, for example, spot welding to the flange, or by laser welding to the flange, such as remote laser welding or remote laser stitch welding. In certain embodiments, 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 installed floor panel reinforcement member 1, together with the floor panel 3, forms a front longitudinal hollow volume 10 in the longitudinal direction and a front transverse hollow volume 20 in the transverse direction. The front longitudinal hollow volume 10 extends substantially longitudinally from the dash panel 4 to the front transition section 31. The transverse hollow volume 20 extends substantially transversely between the left and right side sills 61, 62. The front longitudinal and transverse hollow volumes 10, 20 are connected at the front transition section 31.

[0037] The aforementioned front longitudinal and lateral hollow volumes 10 and 20 are important for withstanding collision energy, absorbing collision energy, and increasing the overall rigidity of the vehicle. In fact, thanks to the presence of these hollow volumes, the overall inertia of the vehicle, and therefore its structural resistance, can be guaranteed.

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

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

[0040] For example, a single metal blank is a laser-welded blank formed from several subblanks joined together by laser butt welding, or by spot welding or a combination of both. For example, a single metal blank is a tailor-rolled blank.

[0041] The fact that floor panel reinforcement members are formed from a single metal sheet significantly simplifies the manufacturing process compared to conventional designs where 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 a reduction in CO2 emissions during vehicle manufacturing.

[0042] A further advantage of incorporating longitudinal and transverse elements into a single part made from a single blank is the absence of assembly points that can introduce structural weaknesses. In fact, because the part is a single upright element, it does not contain assembly points between different sub-parts that are potential structural weaknesses. For example, when individual parts of a conventional multi-part design are welded to each other, the heat-affected zone or weld nugget itself generated by the welding process can become a structural weakness of the assembly, which can lead to failure in the event of a collision or due to fatigue stress or other causes. Furthermore, the absence of assembly points also allows for optimal structural cooperation between different elements of the reinforcing structure. For example, when a part is subjected to longitudinal stress in the event of a frontal collision, the front longitudinal portion 11 plays a significant role in resisting and absorbing the collision energy, but it can also rely on the front transverse portion 21 to resist and absorb some of the collision energy, or it can redirect the collision energy laterally to resist absorbing the collision energy and involve as much of the vehicle structure as possible.

[0043] Furthermore, the absence of assembly points between some individual parts contributes to the overall weight reduction. In fact, assembling several parts requires overlapping areas where two thicknesses of metal overlap, which results in increased weight compared to an assembled design.

[0044] In a particular embodiment as shown in Figure 2, the front longitudinal portion 11 includes a front longitudinal rib 12 located on the longitudinal portion. The rib 12 improves the rigidity of the front longitudinal portion 11, and therefore its impact resistance and rigidity performance.

[0045] In a particular embodiment as shown in Figure 2, the front transverse portion 21 includes a front longitudinal rib 22 located on the longitudinal portion. The rib 22 improves the rigidity of the front longitudinal portion 21, and therefore its collision resistance and rigidity performance.

[0046] In certain embodiments, a specific ratio limit is set between the radius of curvature of the side wall of the transition portion 31 and the height of the side wall of the transition portion 31. More precisely, referring to Figures 8A and 8B, H1 and H2 are the heights of the left and right side walls of the transition portion 31 at the point where the side wall forms a 20° angle with the lateral direction, respectively. In Figures 8A and 8B, the points where the left and right side walls form a 20° angle with the lateral direction are indicated by A1 and A2, respectively.

[0047] For example, as shown in Figure 3, if there are several separate front longitudinal portions 11 in the design of the floor panel reinforcing member, and therefore several front transition portions 31, then it is necessary to consider the contribution of each of these transition portions 31 to the aforementioned ratio.

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

[0049] In a particular embodiment, 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 the separate front longitudinal portions 11, is at least 4. This can be expressed by the following formula:

[0050]

number

[0051] The inventors have found that collision performance, particularly resistance to lateral impact collisions, is improved by making the minimum ratio between the curvature of the sidewall in the transition section and the height of the sidewall in the transition section closer to that of the lateral section. In fact, when faced with a lateral impact, the sidewall of the front lateral section acts to absorb and resist the compressive impact load. The curvature of the sidewall of the transition section 31 potentially represents a vulnerability toward the compressive load, where stress concentration can lead to 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 reinforcing member.

[0052] For example, the inventors have found that very good lateral impact behavior can be obtained by using the following floor panel reinforcing member.

[0053] [Table 1]

[0054] In certain embodiments, the front longitudinal portion 11 further includes a deformable portion extending across the front of the front longitudinal portion 11 and a non-deformable portion extending across the rear of the portion 11. The resistance of the deformable portion to plastic deformation is lower than that of the non-deformable portion. For example, the product of the average thickness and tensile strength of the deformable portion is lower than the product of the tensile strength due to the average thickness of the non-deformable portion. Preferably, in the case of a frontal impact, this makes it possible 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 a portion of the impact energy. At the same time, the non-deformable portion located at the rear and therefore closest to the vehicle occupants resists intrusion and therefore protects the occupants and the HV battery housing, while transferring the remaining energy of the impact to the rest of the vehicle structure.

[0055] In certain embodiments, the front lateral portion 21 further comprises a deformable portion extending over the distal portion of the front lateral portion and a non-deformable portion extending over the central portion of the portion. In certain embodiments, the deformable portion is located on both sides of the front lateral portion. The resistance of the deformable portion to plastic deformation is lower than the resistance of the non-deformable portion to plastic deformation. For example, the product of the average thickness and tensile strength of the deformable portion is lower than the product of the tensile strength due to the average thickness of the non-deformable portion. Preferably, in the case of a lateral impact, this makes it possible 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 a portion of the impact energy. At the same time, the non-deformable portion located towards the center and therefore closest to the vehicle occupants resists intrusion and therefore protects the occupants and HV battery housing, while transferring the remaining impact energy to the rest of the vehicle structure.

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

[0057] In a specific embodiment shown in Figure 2, the floor panel reinforcement member 1 consists only of a front longitudinal portion 11 and a front transverse portion 21. For example, the front longitudinal portion is centrally located and aligned with, for example, 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 transverse portion replaces a front seat floor cross member.

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

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

[0060] In the specific embodiments shown in Figures 3 and 4, the floor panel reinforcing member 1 comprises a front lateral portion 21 and at least one further lateral portion 22, the further lateral portion 22 substantially extending laterally between the side sills 61, 62 and having a side wall extending at least in the height direction such that the further lateral portion 22 together with the floor panel 3 forms a further lateral hollow volume. Preferably, this allows for the further incorporation of lateral intersecting members into the floor panel reinforcing member, further taking advantage of the aforementioned benefits of simplified production and structural optimization.

[0061] In certain embodiments, the floor panel reinforcement member 1 comprises a further lateral portion 22 having a deformable portion extending over the distal portion of the further lateral portion and a non-deformable portion extending over the central portion of the portion. In certain embodiments, the deformable portion is located on both sides of the further lateral portion. The resistance of the deformable portion to plastic deformation is lower than the resistance of the non-deformable portion to plastic deformation. For example, the product of the average thickness and tensile strength of the deformable portion is lower than the product of the tensile strength due to the average thickness of the non-deformable portion. Preferably, in the case of a lateral impact, this makes it possible 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 a portion of the impact energy. At the same time, the non-deformable portion located towards the center and therefore closest to the vehicle occupants resists intrusion and therefore protects the occupants and HV battery housing, while transferring the remaining energy of the impact to the rest of the vehicle structure. When this embodiment is combined with the aforementioned embodiment, in which the anterior lateral portion 21 also has a distal portion having a deformable portion, the deformable portion of the anterior lateral portion 21 and one or more further lateral portions 22 can cooperate to absorb energy together in the event of a lateral impact, while the non-deformable portion cooperates to resist penetration.

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

[0063] In a particular embodiment shown in Figure 4, an additional lateral portion 22 is attached to the floor panel reinforcement member by a central intermediate portion 24. For example, the central intermediate portion 34 has side walls that extend at least in the height direction and, together with the floor panel 3, form an additional longitudinal hollow volume. Preferably, this extends the load path of the front longitudinal portion, thereby increasing resistance to frontal impacts. This also improves the overall rigidity 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 a very large floor panel reinforcement member and thus provides further advantages of the aforementioned benefits of component integration.

[0065] In a particular embodiment shown in Figure 6, the floor panel reinforcing member comprises two further lateral portions 22 that are attached to each other and directly to the front lateral portion 21. This allows for a very robust, compact, durable, and rigid design.

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

[0067] In certain embodiments, floor panel reinforcing members are formed by hot stamping, and the blanks used to produce them include one of the following materials, either in the form of monolithic blanks or combined in the form of tailored blanks.

[0068] - A steel having a composition in weight percent of 0.06% ≤ C ≤ 0.1%, 1% ≤ Mn ≤ 2%, Si ≤ 0.5%, Al ≤ 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%, containing less than 0.1% Cu, Ni, and Mo, with the remainder being iron and unavoidable impurities resulting from refinement. Within this composition range, the yield strength of the corresponding region after hot stamping falls between 700 and 950 MPa, the tensile strength falls between 950 and 1200 MPa, and the bending angle exceeds 75°. For example, this material is used in the deformable parts of floor panel reinforcement members because, combined with its high bending angle and high mechanical properties, it can absorb a large amount of impact energy, for example, by bottling.

[0069] A steel having a maximum tensile strength after hot stamping between -1300 MPa and 1650 MPa, and a yield strength between 950 MPa and 1250 MPa.

[0070] Steel with a maximum tensile strength after hot stamping between -1300 MPa and 1650 MPa, a yield strength between 950 MPa and 1250 MPa, and a bending angle greater than 75°.

[0071] - A steel having a composition in weight %, containing 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%, with the remainder being iron and unavoidable impurities resulting from refinement. Within this composition range, the maximum tensile strength of the corresponding area of ​​the hot-stamped part falls between 1300 MPa and 1650 MPa, and the yield strength falls between 950 MPa and 1250 MPa. For example, this steel composition is used for the non-deformable portion of floor panel reinforcement members because, thanks to its high mechanical properties, it allows for resistance to intrusion.

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

[0073] - A steel having a composition in weight percent containing 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%, with the remainder being iron and unavoidable impurities resulting from refinement. In this composition range, the tensile strength of the corresponding area of ​​the pre-assembly after hot stamping is higher than 1800 MPa. This material is used, for example, in non-deformable parts.

[0074] - A steel having a composition in weight percent of 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 containing in weight percent one or more of the following elements, namely Mo≦0.40%, Nb≦0.08%, Ca≦0.1%, with the remainder being iron and unavoidable impurities resulting from smelting. In this composition range, the tensile strength of the corresponding area of ​​the floor panel reinforcement member after hot stamping is greater than 1350 MPa and the bending angle is greater than 70°.

[0075] - A steel having a composition in weight percent of 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, in weight percent of one or more of the following elements, namely Ni≦0.5%, Mo≦0.40%, Nb≦0.08%, Ca≦0.1%, with the remainder being iron and unavoidable impurities resulting from smelting. In this composition range, the tensile strength of the corresponding area of ​​the floor panel reinforcement member after hot stamping is greater than 1500 MPa and the bending angle is greater than 70°.

[0076] - A steel having a composition in which, by 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, in weight percent, one or more of the following elements, namely Al: ≤ 0.2%, Cr ≤ 0.8%, Nb ≤ 0.06%, Ti ≤ 0.06%, B ≤ 0.005%, Mo ≤ 0.35%, with the remainder being iron and unavoidable impurities resulting from smelting. In this composition range, the tensile strength of the corresponding area of ​​the floor panel reinforcement member after hot stamping is 1000 MPa or greater, and the bending angle is greater than 55°.

[0077] -A steel having a composition in weight percent containing 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 combinations, namely 114-68*C-18*Mn+20*Si-56*Cr-60*Ni-36*Al+38*Mo+79*Nb-17691*B<20, where the remainder of the composition is iron and unavoidable impurities resulting from smelting. For example, this composition is used when hot stamping parts using a multi-stage process.

[0078] - Steel coated with an aluminum-based metal coating. "Aluminum-based" means a coating containing at least 50% aluminum by weight. For example, the metal coating is an aluminum-based coating containing 8-12% Si by weight. The metal coating is applied, for example, by immersing the substrate in a molten metal bath. Preferably, applying an aluminum-based metal coating avoids the formation of surface scale during the heating step of the hot stamping process, thereby enabling the production of parts by hot stamping without the subsequent sandblasting process. Furthermore, the aluminum-based coating also provides corrosion protection to the parts during use in vehicles.

[0079] - Steel coated with an aluminum-based metal coating containing 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 further elements selected from Pb, Ni, Zr, or Hf, wherein the weight content of each further element is less than 0.3%, with the remainder being aluminum and optionally unavoidable impurities. Preferably, this type of metal coating provides very good corrosion resistance on the part, as well as a good surface appearance after hot stamping.

[0080] In certain embodiments, at least the upper or lower shell is formed by hot stamping a laser-welded blank comprising at least one subblank having an aluminum-based metal coating, the aluminum-coated subblank being pre-prepared by ablating at least a portion of the metal coating on the edges to be welded. Preferably, this removes some of the aluminum present in the coating that would contaminate the weld seam and degrade its mechanical properties.

[0081] In certain embodiments, a floor panel reinforcement member is formed by hot stamping a laser-welded blank comprising at least one subblank having at least one side covered with an emissivity-enhancing upper layer. The emissivity-enhancing upper layer is applied to the outermost surface of the subblank. The emissivity-enhancing upper layer allows the surface of the subblank to have a higher emissivity compared to the same subblank not coated with the emissivity-enhancing upper layer. The emissivity-enhancing upper layer may be applied to either the upper or lower surface of the subblank. Alternatively, the emissivity-enhancing upper layer may be applied to both sides of the subblank. If the subblank has a metal coating as described above, the emissivity-enhancing upper layer is applied on the metal coating. In practice, the emissivity-enhancing upper layer needs to cover the outermost surface of the subblank in order to increase the surface emissivity. Preferably, the emissivity-enhancing upper layer allows the heating rate of the subblank to be increased, and therefore the productivity of the heating step in the hot stamping process to be increased. When using several subblanks of different thicknesses, the emissivity-enhancing top layer is preferably applied to the subblank having the highest thickness in order to reduce the difference in heating time between the different subblanks, thus increasing productivity, extending the hot stamping process window, and enabling the final part to have uniform surface properties overall.

Claims

1. A floor panel reinforcing member (1) for an automobile (100) is attached to a floor panel (3) and comprises at least a front longitudinal portion (11), a front transverse portion (21), and a front transition portion (31), - The front longitudinal portion (11) has at least left and right side walls that extend at least in the height direction from the floor panel (3) to a height higher than the floor panel (3), the front lateral portion (21) has at least front and rear side walls that extend at least in the height direction from the floor panel (3) to a height higher than the floor panel (3), and the front transition portion (31) has at least left and right side walls that extend at least in the height direction from the floor panel (3) to a height higher than the floor panel (3), - The front longitudinal portion (11) extends longitudinally from the dash panel (4) to the front transition portion (31), and together with the floor panel (3), forms a front longitudinal hollow volume (10). - The front lateral portion (21) extends laterally between the left and right side sills (61, 62) of the automobile, and together with the floor panel (3) forms a front lateral hollow volume (20), and is connected to the front longitudinal portion (11) at the front transition portion (31). It is designed to be so The floor panel reinforcing member (1) is manufactured by forming a single metal blank (7), - comprising n distinct front longitudinal portions (11) and associated front transition portions (31), where n is an integer of 1 or more, -Each forward transition section (31) is provided with left and right side walls, and these side walls each have radii of curvature R1 and R2, and heights H1 and H2, which are defined as the heights in the height direction of the left and right side walls of the forward transition section at the point where the side wall forms a 20° angle with the lateral direction. The product of the ratio of the sum of the curvature radii R1 and R2 of the side walls of the pre-transition section to the sum of the heights H1 and H2 of the side walls of the pre-transition section, and n, is 4 or greater, as shown in the following formula [Equation 1]. [Math 1] A floor panel reinforcing member (1) for an automobile (100).

2. The floor panel reinforcing member (1) for an automobile (100) according to claim 1, wherein the single metal blank (7) is a laser-welded blank comprising several subblanks.

3. The floor panel reinforcing member (1) for an automobile (100) according to claim 1 or 2, wherein the floor panel reinforcing member (1) is manufactured by hot stamping the single metal blank (7).

4. The floor panel reinforcing member (1) according to claim 1 or 2, further comprising at least one further lateral portion (22) extending laterally between side sills (61, 62) and having a side wall, wherein the side wall extends at least in the height direction such that the at least one further lateral portion (22) together with the floor panel (3) forms a further lateral hollow volume, and the at least one further lateral portion (22) is attached to the floor panel reinforcing member by a lateral intermediate portion (23) extending longitudinally between the sides of the lateral portions (21, 22).

5. The floor panel reinforcing member (1) according to claim 1 or 2, further comprising at least one further lateral portion (22) extending laterally between the side sills (61, 62) and having a side wall, wherein the side wall extends at least in the height direction such that the at least one further lateral portion (22) together with the floor panel (3) forms a further lateral hollow volume, and the at least one further lateral portion (22) is attached to the floor panel reinforcing member by a central intermediate portion (24).

6. An automobile (100) comprising the floor panel reinforcing member (1) according to claim 1 or 2.

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