Vehicle floor and corresponding manufacturing method

Abstract

The present invention relates to a hot stamped vehicle floor (1) for a vehicle frame (100), the floor including a main floor panel (2) stamped from at least one sheet metal blank. The floor further includes at least one sheet metal reinforcement patch (4) disposed on and overlapping the main floor panel (2). The reinforcement patch (4) is more ductile than the main floor panel (2). The at least one reinforcement patch (4) is bonded to at least one area (6) of the main floor panel (2) that is expected to withstand compressive impact forces during a vehicle collision, and the main floor panel (2) and the at least one reinforcement patch (4) are bonded to each other before the vehicle floor (1) is stamped. The present invention also relates to a method for manufacturing a vehicle. TIFF2023500810000002.tif99128

Description

Technical Field

[0001] Field of the Invention The present invention relates to a hot stamping vehicle floor for a vehicle frame, including a main floor panel punched from sheet metal.

[0002] The present invention further relates to a method for manufacturing a hot stamping vehicle floor for a vehicle frame, including the step of hot stamping at least one sheet metal blank to punch the main floor panel.

Background Art

[0003] Prior Art A vehicle floor for a vehicle frame includes a plurality of different stamped sheet metal components and reinforcements that need to be joined together to obtain the final vehicle floor. This implies a very intensive welding assembly operation. Welding is known to be a difficult manufacturing process as it absorbs the risk of dimensional distortion due to local heating. In addition, special support tools are required to join the parts together.

[0004] Furthermore, after being fully assembled, the floor must be supplied to a frame mounting line in order to be assembled to the vehicle frame. A pre-assembled floor is a heavy and large component that is difficult to handle from a logistics perspective.

[0005] On the other hand, various floor components can be manufactured by various hot or cold forming methods, such as cold stamping, hot stamping (also known as press hardening), roll forming or indirect hot stamping (also known as indirect press hardening).

[0006] Among various technologies, hot stamping is a particularly desirable method. The reason is that it enables the production of components with a very high yield strength of 1,200 MPa to 2,000 MPa. However, these components cannot be used in the area of the vehicle floor that is assumed to withstand the compressive impact force during a collision. These components are very hard but at the same time brittle. Therefore, during a collision, this rigidity may cause unwanted mechanical cracks in the components, preventing the components from fulfilling their safety functions. For this reason, the floor has to be customized from a plurality of individual components with different mechanical properties according to the need for specific deformation in each area. As a result, dedicated tools and dies are required for each individual component. Also, very considerable welding costs are required.

[0007] In addition, with the popularization of hybrid vehicles and electric vehicles, the vehicle frame, such as an automobile frame, is increasingly frequently required to provide as much space as possible in the floor area to accommodate the vehicle's battery.

[0008] The battery is a very heavy and large component, and due to its weight, it has to be accommodated as low as possible in the vehicle frame so as not to interfere with the vehicle dynamics as much as possible. Usually, the battery is in the shape of a parallelepiped box with a very long and wide bottom. The battery also extends mainly in the longitudinal direction of the vehicle and has a reduced height to create space for the vehicle's internal components. The arrangement of the battery forces a complete redesign of the conventional vehicle floor dimensions and shape to fulfill both the function of the security cell and the battery accommodation function.

[0009] DE202010017552U1 (Patent Document 1) discloses a body structure for a bicycle, particularly a floor structure, having structural components that define load paths for use during a collision. In the area of the structural components arranged in at least one defined load path, particularly a load path during a frontal collision and / or a load path during a side collision and / or a load path during a rear-end collision, the components are formed from hot-stamped or cold-stamped steel sheets, at least partially by high-strength structural components, preferably completely hardened or at least partially hardened high-strength structural components, and those components are directly or indirectly, preferably directly, connected to each other, particularly firmly connected to each other via a force and / or shape and / or material connection.

[0010] US2014147693A1 (Patent Document 2) discloses a molded member that can be manufactured at low cost, has excellent dimensional accuracy, has excellent axial crushability and three-point bendability, has excellent bending rigidity and torsional rigidity, and is suitable for use in components of a bicycle. The molded member has a reinforcing member joined to a ridge portion by welding. This molded member is manufactured by welding a flat sheet metal blank and a flat sheet metal reinforcing member and performing bending so that the welded portion becomes a ridge portion.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Summary of the Invention

[0012] The object of the present invention is to propose a hot stamping vehicle floor for a vehicle frame that is easier to manufacture than a conventional vehicle floor and is lighter than a conventional vehicle floor. This object is achieved by a hot stamping vehicle floor of the type indicated at the beginning, which is characterized in that: it further comprises at least one sheet metal reinforcement patch arranged on and overlapping the main floor panel, the at least one reinforcement patch being more ductile than the main floor panel, the at least one reinforcement patch being joined to at least one area of the main floor panel, the at least one area being assumed to withstand a compressive collision force during a collision of the vehicle, and the main floor panel and the at least one reinforcement patch being joined to each other before the vehicle floor is punched.

[0013] The steel used for the press hardening process is a boron steel called 22MnB5. This type of steel is usually coated with an AlSi layer to improve its corrosion resistance. This type of steel can also be hardened when it is first heated to a temperature of about 900 °C that provides austenite microstructure formation and then quenched (known as the quenching process), thereby obtaining a martensite structure.

[0014] A second type of press hardened steel is multi-stage press hardened steel. This type of steel is also a boron steel but has a slightly different composition from the conventional boron steel. This type of boron steel is called 22MnB8. This type of steel is usually coated with a zinc layer that has better behavior against corrosion than AlSi. To obtain a hard microstructure, the steel can be heated to the austenitization temperature (about 900 °C) and cooled at a very low cooling rate (room temperature air cooling rate), thereby obtaining a martensite microstructure.

[0015] Non-hardening steel can also be subjected to the press hardening process, but its hardness does not increase as a result of the press hardening process.

[0016] As is well known to those skilled in the art, the term "ductility" refers to a measure of the ability of a material to undergo plastic deformation before fracture. Ductility is more generally expressed as the elongation or reduction of area from a standard tensile test conforming to the following ISO standard "ISO 6892-1:2016 Metallic materials - Tensile testing - Part 1: Method of test at room temperature".

[0017] A preferred method for calculating ductility is based on the elongation of the metal probe during a tensile test as follows. Elongation rate = (L f - L0) / L0 L0 is the initial probe length, and L f is the probe length before fracture.

[0018] Alternatively, it can also be measured according to the reduction of area. Reduction of area rate = (A0 - A f ) / A0 A0 is the initial probe cross-sectional area, and A f is the probe cross-sectional area before fracture.

[0019] In addition, in the present invention, the expression "assumed to withstand the compressive collision force during a vehicle collision" refers to a vehicle area where the vehicle frame is designed to withstand the compressive force during a collision based on the design experience or know-how of those skilled in the art. However, ultimately, depending on the direction of the collision, it may happen that these areas must also withstand other types of acting forces.

[0020] Finally, when the sheet metal reinforcement patch is disposed on the main floor panel and overlaps the main floor panel, in this area, the thickness of the assembly is the sum of the thickness of the main floor panel and the thickness of the reinforcement patch.

[0021] Returning to the solution proposed by the present invention, if the part is easily hot-stamped, the reinforcement patch completely covers the overlapping area with the main floor panel, increasing the vehicle floor thickness by the thickness of the patch.

[0022] A combination of a soft material and a hard material that overlaps in an area assumed to withstand a compressive impact force during a collision, and a fully hardened material obtained by hot stamping can increase the bending angle. Now, these areas can withstand greater deformation without the risk of rupture, making the vehicle obtained with the hot stamping material suitable for safety applications.

[0023] In addition, the vehicle floor of the present invention dramatically reduces the number of parts required to obtain the final vehicle floor. This leads to simplification of manufacturing and cost reduction because the number of parts that have to be joined together by welding after being separately formed is reduced. Furthermore, there is a possibility of using more hot stamping sheet metal blanks, the thickness of the parts can also be reduced, and together with the amount of individual part reduction, the associated weight reduction can be achieved.

[0024] The hot stamping process of the present invention includes any hot stamping process, such as direct or indirect hot stamping, also known as press hardening or indirect press hardening, and multi-stage hot stamping or press hardening processes.

[0025] The conventional press hardening process is as follows. (a) The sheet metal blank starts the process at room temperature, (b) Next, the blank is heated in a furnace to about 900 °C to obtain an austenite microstructure, (c) Next, the blank is placed in a press die, formed into the desired part shape, and held in the closed position of the die for several seconds, thereby quenching the blank, (d) This cooling transforms austenite into martensite, thereby obtaining a harder part.

[0026] Finally, some additional operations may be required after cooling.

[0027] The indirect press hardening process is as follows. (a) The sheet metal blank starts the process at room temperature, (b) Preform the blank in a cold stamping die into a desired preformed part. (c) Then heat the preformed part in a furnace to about 900 °C to obtain an austenite microstructure. (d) Next, place the part in a press die, form it, and hold it in the closed position for several seconds, thereby quenching the blank. (e) This cooling transforms the austenite to martensite, providing the final hardness to the part.

[0028] Finally, multi-stage press hardening requires the use of special press hardening steels. Some steel manufacturers are developing steels that can be hardened without quenching. This type of steel is sometimes called air hardening steel. Their microstructure can transform from austenite to martensite without a quenching process.

[0029] In the case of the multi-stage press hardening process, the process occurs as follows. (a) A sheet metal blank starts the process at room temperature. (b) Then heat the blank in a furnace to about 900 °C to obtain an austenite microstructure. (c) Next, place the blank in a multi-stage press die and form it into the desired part shape. As the part advances within the die, different forming steps occur. First, cool the blank to about 500 °C, then form it, and then post-process it as needed. (d) In this case, there is no need for quenching. Cool the finished part to room temperature.

[0030] The present invention further includes several preferred features which are the subject of the dependent claims, and their advantages are emphasized in the following detailed description of the embodiments of the invention.

[0031] Preferably, the main floor panel is made of press hardening steel, also known as hot forming steel, and the reinforcement patch is made of non-hardening steel.

[0032] In a preferred embodiment for reinforcing the vehicle floor, the main floor panel includes at least one reinforcing beam directly punched from the sheet metal blank, and the at least one reinforcing patch is disposed on and joined to the at least one reinforcing beam of the vehicle floor.

[0033] In another preferred embodiment for determining an increase in the bending angle of a region assumed to withstand a compressive collision force during a collision, the at least one reinforcing patch is 10% to 80%, preferably 25% to 70% more ductile than the main floor panel.

[0034] To simplify vehicle floor manufacturing and its adaptability, the main floor panel and the reinforcing patch have a thickness of 0.5 to 8 mm, preferably 0.5 to 6 mm, more preferably 0.5 to 3 mm, and particularly preferably 0.8 to 1.5 mm.

[0035] Also, in a preferred embodiment, to reduce logistics costs, the main floor panel and the reinforcing patch have the same thickness. This avoids the need to handle many different blank thicknesses.

[0036] Preferably, to avoid early corrosion of the vehicle frame, the main floor panel and the reinforcing patch are zinc-coated.

[0037] In a preferred embodiment to provide improved side collision behavior, the vehicle floor defines a longitudinal direction corresponding to the driving direction and a perpendicular direction, and the at least one reinforcing patch extends in the perpendicular direction.

[0038] In the case of a motor vehicle frame, the frame typically has three pillars known as A, B, and C. In a five-door vehicle, the B-pillar is assumed to hinge the door providing access to the second seat row. More precisely, this central area of the motor vehicle is relatively less rigid in the motor vehicle frame. The vehicle frame, more specifically the vehicle floor, also includes seat cross-members which, apart from their function of providing attachment points to the seat structure, cooperate in stiffening the vehicle frame and its safety cell. Thus, in order to improve the safety cell function of the vehicle frame, at least one reinforcement patch of the vehicle floor overlaps the position of the seat cross-member of the main floor panel.

[0039] To reduce manufacturing complexity, the main floor panel is made from a single sheet metal blank. In this way, a complete floor can be manufactured in a single hot stamping process, significantly reducing or minimizing the need for post-welding processes.

[0040] In another aspect, the main floor panel and the at least one reinforcement patch are joined together by one or more methods from the group consisting of resistance spot welding, standard laser welding, remote laser welding, resistance seam welding (RSEW), gas metal arc welding, and laser-arc hybrid welding.

[0041] Also, in order to obtain an optimal degree of ductility in the area assumed to withstand compressive forces during a collision, the main floor panel has a tensile strength of 1,400 MPa to 2,000 MPa, and the at least one sheet metal reinforcement patch has a tensile strength of 500 to 1,000 MPa.

[0042] The present invention further relates to a method for manufacturing a hot stamping vehicle floor for a vehicle frame, the method being such that the floor is easier to manufacture and lighter than vehicle floors of the prior art.

[0043] Before the hot stamping process, the present invention further includes a step of disposing at least one reinforcing patch on the sheet metal blank and overlapping the sheet metal blank on at least one area of the vehicle floor that is assumed to withstand the compressive impact force during a collision, and a step of joining the at least one reinforcing patch and the sheet metal blank. This problem is solved by the above method.

[0044] As will be further described below, the method of the present invention provides a much simpler vehicle floor with much fewer parts and significant weight reduction.

[0045] In a preferred embodiment, the joining step is carried out by one or more methods selected from the group consisting of resistance spot welding, standard laser welding, remote laser welding, resistance seam welding (RSEW), gas metal arc welding, and laser-arc hybrid welding.

[0046] Also, in the method of the present invention, it is preferable that the main floor panel is made of press-hardened steel and the reinforcing patch is made of non-hardened steel.

[0047] [The present invention 1001] A hot stamping vehicle floor (1) for a vehicle frame (100), comprising: [a] A main floor panel (2) punched from at least one sheet metal blank ; and the following: [b] The main floor panel (2) is made from a single sheet metal blank, and the vehicle floor (1) further comprises: [c] At least one sheet metal reinforcement patch (4) disposed on and overlapping the main floor panel (2), wherein: [d] The at least one reinforcement patch (4) is more ductile than the main floor panel (2), [e] The at least one reinforcement patch (4) is joined to at least one area (6) of the main floor panel (2), and the at least one area (6) is assumed to withstand a compressive collision force during a collision of the vehicle, [f] The main floor panel (2) and the at least one reinforcement patch (4) are joined to each other before the vehicle floor (1) is punched characterizing the hot stamping vehicle floor (1). [The present invention 1002] The vehicle floor (1) according to the present invention 1001, characterized in that the main floor panel (2) is made of press-hardened steel and the reinforcement patch (4) is made of non-hardened steel. [The present invention 1003] The vehicle floor (1) according to the present invention 1001 or 1002, characterized in that the main floor panel (2) includes at least one reinforcement beam directly punched from a sheet metal blank, and the at least one reinforcement patch (4) is disposed on and joined to the at least one reinforcement beam of the vehicle floor (1). [The present invention 1004] The vehicle floor (1) according to any one of the present inventions 1001 to 1003, characterized in that the at least one reinforcement patch (4) is 10% to 80%, preferably 25% to 70% more ductile than the main floor panel (2). [The present invention 1005] The vehicle floor (1) according to any one of the present inventions 1001 to 1004, characterized in that the main floor panel (2) and the reinforcement patch (4) have a thickness of 0.5 to 8 mm, preferably 0.5 to 6 mm, more preferably 0.5 to 3 mm, and particularly preferably 0.8 to 1.5 mm. [The present invention 1006] The vehicle floor (1) according to the present invention 1005, characterized in that the main floor panel (2) and the reinforcement patch (4) have the same thickness. [The present invention 1007] The vehicle floor (1) according to any one of the present inventions 1001 to 1006, characterized in that the main floor panel (2) and the reinforcing patch (4) are zinc-coated. [The present invention 1008] The vehicle floor (1) according to any one of the present inventions 1001 to 1007, characterized in that the vehicle floor (1) defines a longitudinal direction (L) corresponding to the driving direction and a vertical direction (P), and at least one reinforcing patch extends in the vertical direction (P). [The present invention 1009] The vehicle floor (1) according to any one of the present inventions 1001 to 1008, characterized in that the main floor panel (2) and at least one reinforcing patch (4) are joined together by one or more methods from the group consisting of resistance spot welding, standard laser welding, remote laser welding, resistance seam welding (RSEW), gas metal arc welding, and laser-arc hybrid welding. [The present invention 1010] The vehicle floor (1) according to any one of the present inventions 1001 to 1009, characterized in that at least one sheet metal blank for manufacturing the main floor panel (2) has a tensile strength of 1,400 MPa to 2,000 MPa, and at least one sheet metal reinforcing patch (4) has a tensile strength of 500 to 1,000 MPa. [The present invention 1011] A method for manufacturing a hot stamping vehicle floor (1) for a vehicle frame (100), [a] a step of hot stamping at least one sheet metal blank to punch out the main floor panel (2) including; the following: [b] characterized in that the main floor panel (2) is made from a single sheet metal blank, and, the following: before the hot stamping step, [c] a step of disposing at least one reinforcing patch (4) on the sheet metal blank and overlapping at least one area (6) of the vehicle floor (1) that is assumed to withstand a compressive impact force during a collision, the at least one reinforcing patch (4) being more ductile than the main floor panel (2), [d] a step of joining the at least one reinforcing patch (4) and the sheet metal blank, further including characterized by a method. [The present invention 1012] The method of the present invention 1011, characterized in that the step of joining is carried out by one or more methods from the group consisting of resistance spot welding, standard laser welding, remote laser welding, resistance seam welding (RSEW), gas metal arc welding and laser-arc hybrid welding. [The present invention 1013] The method of the present invention 1011 or 1012, characterized in that the main floor panel (2) is made of press-hardened steel and the reinforcing patch (4) is made of non-hardened steel. Similarly, the present invention also includes other detailed features shown in the detailed description of the embodiments of the present invention and the accompanying drawings.

Brief Description of the Drawings

[0048] Further advantages and features of the present invention will become apparent from the following detailed description in which preferred embodiments of the present invention are disclosed with reference to the accompanying drawings without limitation.

[0049] [Figure 1] Perspective view of a prior art vehicle floor. [Figure 2] It is a perspective view of the vehicle floor of the present invention. [Figure 3] It is a side view of the vehicle floor of FIG. 2. [Figure 4] It is a plan view of the vehicle floor of FIG. 2 showing a reinforcing patch disposed on the reinforcing beam. [Figure 5] It is a vehicle frame including the floor of the present invention. [Figure 6] It is a detailed view of the vehicle frame of FIG. 5 during a side collision. [Figure 7] It is a numerical simulation of the area shown in FIG. 6 of the vehicle floor of FIG. 2 during a collision. [Figure 8] It is a detailed view of the vehicle floor of the present invention in which the floor panel and the reinforcing patch are spot welded. [Figure 9] It is a detailed view of the vehicle floor of the present invention in which the floor panel and the reinforcing patch are laser welded. [Figure 10] It is a graphical representation of the first aspect of the method of the present invention.

Mode for Carrying Out the Invention

[0050] Detailed Description of Aspects of the Invention FIG. 1 shows a prior art vehicle floor 200. This prior art vehicle floor includes a plurality of sheet metal parts such as a front panel 202, a cross beam 204, a longitudinal beam 206, a beam reinforcement 208, a rear panel 210, a middle panel 212, and the like. This vehicle floor 200 is composed of a total of 16 individual stamped sheet metal parts. These 16 parts must be appropriately joined by any suitable welding process, such as spot welding, laser welding, etc. after being individually formed. When completed, the vehicle floor 30 has a weight exceeding 30 kg.

[0051] In order to solve the problem of proposing a hot stamping vehicle floor for a vehicle frame that is easier to manufacture and lighter in weight than the prior art vehicle floor, the present invention anticipates a hot stamping vehicle floor 1 for a vehicle frame 100, which includes a main floor panel 2 punched from at least one sheet metal blank with a thickness of 1 mm, and it is particularly preferable that it is made from one single sheet metal blank. Preferably, the main floor panel 2 is made from hot formed steel.

[0052] As is apparent from FIGS. 3 and 4, the vehicle floor 1 defines a longitudinal direction L corresponding to the driving direction and a perpendicular direction P, and the at least one reinforcing patch extends in the perpendicular direction P.

[0053] In the floor of FIGS. 2 to 7, in order to solve the problems of the present invention, the vehicle floor 2 further includes two sheet metal reinforcing patches 4 disposed on the main floor panel 2 and overlapping the main floor panel 2. Preferably, the reinforcing patch 4 is made from a hot formed steel sheet with a thickness of 1 mm.

[0054] The two reinforcing patches 4 are more ductile than the main floor panel 2. In particular, the reinforcing patch 4 is 10% - 80%, preferably 25% - 70% more ductile than the main floor panel 2. The main floor panel 2 has a tensile strength of 1,400 MPa - 2,000 MPa, and the sheet metal reinforcing patch 4 has a tensile strength of 500 - 1,000 MPa.

[0055] Materials that satisfy such conditions are, for example, hot formed grades. The floor panel 2 may be made of steel for hot stamping, such as Usibor® 2000 or 1500 from Arcelor Mittal, and the reinforcing patch 4 may be made of steel for hot stamping, such as Ductibor® 450, 500 or 1000 from the same company as mentioned above.

[0056] It is particularly preferable that both the main floor panel 2 and the reinforcing patch 4 are zinc coated.

[0057] Reinforcement patch 4 is joined to two areas 6 of the main floor panel 2 that are assumed to withstand the compressive collision force during a vehicle collision. In this case, the related overlapping areas 6 correspond to the cross members 12 to which the seats are attached. From FIG. 7, it is clear that in this case, due to structural requirements, the entire cross member of the main floor panel 2 is covered by the reinforcement patch 4. However, when a side collision occurs, the point that receives the action of the highest compression peak is the side edge 12 of the vehicle floor, and this side edge undergoes the maximum deformation.

[0058] Both the main floor panel 2 and the two reinforcement patches 4 are joined to each other by one or more methods from the group consisting of any suitable welding technique, such as resistance spot welding, standard laser welding, remote laser welding, resistance seam welding (RSEW), gas metal arc welding, and laser-arc hybrid welding, before the vehicle floor 1 is punched.

[0059] FIG. 8 shows a manner in which the floor panel 2 and the reinforcement patch 4 are spot welded at a plurality of weld points 8 before being punched. Alternatively, in the manner of FIG. 9, the floor panel 2 and the reinforcement patch 4 are joined by a laser seam 10 obtained by laser welding.

[0060] Also, as already described, the main floor panel 2 includes two reinforcement beams for seat attachment that are directly punched from a sheet metal blank corresponding to a cross member for attaching the vehicle seat. The reinforcement patch 4 is disposed and joined to the reinforcement cross beam of the vehicle floor 1.

[0061] Therefore, if the main floor panel 2 and the reinforcement patch 4 are joined, a hot stamping process for forming the vehicle floor 1 is carried out. In other words, the vehicle floor 1 can be manufactured in one simple hot stamping process.

[0062] Compared with the vehicle floor of FIG. 1, the embodiments shown in FIGS. 2-5 include only three parts and one single forming tool, as compared to the 16 individually manufactured parts of the prior art floor.

[0063] For example, thanks to this design described above, a weight reduction of about 20% can be achieved compared to the floor of FIG. 1. However, depending on the floor design, even higher weight reduction can be achieved. Additionally, despite the part reduction, the vehicle floor can withstand a collision event as well as those shown in FIGS. 6 and 7.

[0064] Finally, FIG. 10 shows an embodiment of the method of the present invention.

[0065] First, from left to right in FIG. 10, a sheet metal blank of hot stamping steel for forming the main floor panel 2 is provided. Two reinforcing patches 4 of non-hardening steel are disposed on the sheet metal blank and overlapped on the area 6 of the vehicle floor 1 that is assumed to withstand the compressive collision force during a collision of the sheet metal blank.

[0066] Next, these two reinforcing patches 4 are welded together. In this embodiment, the welding is carried out by spot welding, but as already explained, other welding methods are also possible.

[0067] If the three blanks are joined together to form one single final blank 18, it is placed in the furnace 14 and heated to about 900°C.

[0068] Finally, the heated final blank 18 is placed in a press hardening die for hot stamping the sheet metal final blank 18 to punch out the main floor panel 2. On the right side of FIG. 10, the overlap between the two reinforcing patches 4 and the main floor panel 2 in the cross beam area 20 is evident.

[0069] The one-piece floor assembly provides weight, part, and welding reduction. The only issue in conventional fully hardened solutions is the high risk of fracture of the fully martensitic material in the crash test. However, this risk is minimized by the addition of a ductile material patch that improves the performance of the fully hardened main floor panel 2 and avoids cracking.

Claims

1. A method for manufacturing a hot stamping vehicle floor (1) for a vehicle frame (100), comprising: [a] hot stamping at least one sheet metal blank for punching out a main floor panel (2); The following: [b] the main floor panel (2) being made from a single sheet metal blank; characterized in that, and the following: Before the hot stamping step, [c] disposing at least one reinforcing patch (4) on the sheet metal blank and overlapping it on at least one area (6) of the vehicle floor (1) which is assumed to withstand the compressive impact force during a collision, the at least one reinforcing patch (4) being more ductile than the main floor panel (2); [d] the main floor panel (2) being made of press-hardened steel and the reinforcing patch (4) being made of non-hardened steel; [e] joining the at least one reinforcing patch (4) and the sheet metal blank; further comprising; A method characterized by the above.

2. The method according to claim 1, characterized in that the joining step is carried out by one or more methods from the group consisting of resistance spot welding, standard laser welding, remote laser welding, resistance seam welding (RSEW), gas metal arc welding and laser-arc hybrid welding.

3. The method according to any one of claims 1 to 2, characterized in that it includes directly punching out at least one reinforcing beam from the sheet metal blank and disposing and joining at least one reinforcing patch (4) to the at least one reinforcing beam of the vehicle floor (1).

4. The method according to any one of claims 1 to 3, characterized in that at least one reinforcing patch (4) is 10% to 80% more ductile than the main floor panel (2).

5. The method according to any one of claims 1 to 3, characterized in that at least one reinforcing patch (4) is 25% to 70% more ductile than the main floor panel (2).

6. The method according to any one of claims 1 to 5, characterized in that the main floor panel (2) and the reinforcing patch (4) have a thickness of 0.5 to 8 mm.

7. The method according to any one of claims 1 to 5, characterized in that the main floor panel (2) and the reinforcing patch (4) have a thickness of 0.5 to 6 mm.

8. The method according to any one of claims 1 to 5, characterized in that the main floor panel (2) and the reinforcing patch (4) have a thickness of 0.5 to 3 mm.

9. The method according to any one of claims 1 to 5, characterized in that the main floor panel (2) and the reinforcing patch (4) have a thickness of 0.8 to 1.5 mm.

10. The method according to any one of claims 7 to 9, characterized in that the main floor panel (2) and the reinforcing patch (4) have the same thickness.

11. The method according to any one of claims 1 to 10, characterized in that the main floor panel (2) and the reinforcing patch (4) are zinc-coated.

12. The vehicle floor (1) is characterized by defining a longitudinal direction (L) corresponding to the driving direction and a vertical direction (P), and at least one reinforcing patch extends in the vertical direction (P). The method according to any one of claims 1 to 11.

13. The method according to any one of claims 1 to 12, characterized in that at least one sheet metal blank for manufacturing the main floor panel (2) has a tensile strength of 1,400 MPa to 2,000 MPa, and at least one sheet metal reinforcing patch (4) has a tensile strength of 500 to 1,000 MPa.

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