Parts and methods for vehicles

Abstract

The present disclosure relates to a component for a vehicle frame, the component comprising a main frame (100) extending longitudinally along the vehicle frame from a front end (200) to a rear end (300). The main frame (100) substantially defines a closed ring shape and comprises first and second cross members (110, 120) and first and second transverse members (130, 140). Furthermore, the main frame (100) is made by deforming a single blank. Additionally, the present disclosure relates to a method for manufacturing such a component.

Description

[Technical Field]

[0001] This application claims the benefit of European Patent Application No. 22 382 870.8, filed September 21, 2022.

[0002] The present disclosure relates to a component for a vehicle framework, the component comprising a main frame substantially defining a ring shape. Additionally, the present disclosure relates to a method for manufacturing such a component. [Background technology]

[0003] Vehicles, such as automobiles, include a structural framework designed to withstand the loads that the vehicle will experience during its lifetime, and the structural framework is further designed to withstand and absorb impacts, for example, in the event of a collision with another automobile or road structure.

[0004] The trend toward manufacturing more efficient vehicles with lower emissions has increased dramatically over recent decades. The rapid development of hybrid and electric vehicles has forced the industry to design new automotive components, namely, to reduce weight and, among other things, to accommodate and protect the new automotive components in order to achieve improved vehicle range.

[0005] The demand for weight reduction in the automotive industry has led to the development and implementation of lightweight materials or components, as well as related manufacturing processes and tools. The demand for weight reduction is driven, among other things, by the goal of reducing CO2 emissions. Furthermore, increasing concerns about occupant safety have also led to the adoption of materials that improve the vehicle's integrity during a crash while also improving energy absorption.

[0006] A process known as Hot Forming Die Quenching (HFDQ) typically uses boron steel sheet to produce pressed parts with Ultra High Strength Steel (UHSS) properties, for example, tensile strengths of 1.500 MPa or 2.000 MPa or greater. The increased strength allows for the use of thinner gauge material, resulting in weight savings compared to traditional cold-pressed mild steel parts. Throughout this disclosure, UHSS can be considered as steels that have an ultimate tensile strength of 1.000 MPa or greater after the press-quench process.

[0007] In the HFDQ process, the blank to be hot-formed can be heated to a predetermined temperature, such as a temperature above the austenitizing temperature (e.g., a temperature between Ac3 and the evaporation temperature of the coating on the blank). For this purpose, a furnace system can be used. Depending on specific needs, the furnace system can be supplemented with additional heaters, such as induction heaters or infrared heaters. Heating the blank reduces its strength and improves its deformability, i.e., facilitating the hot-pressing process.

[0008] Several ultra-high strength steels (UHSS) are known for hot pressing and quenching. Blanks can be made of coated or uncoated boron steels, such as Usibor® (22MnB5) available from ArcelorMittal.

[0009] Hot forming die quenching is sometimes referred to as "press quenching" or "hot pressing", and these terms are used interchangeably throughout this disclosure.

[0010] Hot forming of boron steels is becoming increasingly popular in the automotive industry due to their excellent strength and formability. Thus, many structural parts that were traditionally cold formed from mild steel are being replaced with hot-formed equivalents, which offer significant improvements in strength. This allows for a reduction in material thickness (and therefore weight) while maintaining the same strength. However, hot-formed parts can have poor ductility and energy absorption in the as-formed state.

[0011] To improve ductility and energy absorption in specific regions of a component, it is known to introduce softer regions within the same component. This results in locally improved ductility while maintaining the required overall high strength. By locally tailoring the microstructure and mechanical properties of specific structural components to include regions with very high strength (very hard), i.e., high ultimate tensile strength and high yield strength, and regions with high ductility (softer), i.e., low ultimate tensile strength and low yield strength and high elongation to break, it may be possible to improve their overall energy absorption, maintain their structural integrity in a crash situation, and even reduce their overall weight. Furthermore, such soft zones can favorably alter the kinematic behavior of the component as it collapses upon impact.

[0012] A known method for creating highly ductile regions ("soft regions" or "soft zones") in vehicle structural components involves providing a tool with a pair of complementary upper and lower die units, each unit having a separate die element (steel block). The blank to be hot-formed is preheated, for example by a furnace system, to a predetermined temperature, e.g., the austenitizing temperature or higher, to reduce its strength and thus facilitate the hot-pressing process.

[0013] Die elements can be designed to operate at different temperatures during the quenching process so that different zones of the part being formed have different cooling rates, which can result in different material properties in the final product, such as softer regions that typically have lower ultimate tensile strength and lower yield strength, but allow for greater elongation to break. For example, one die element can be cooled to quickly reduce the temperature of the part being fabricated by quenching that region at a higher cooling rate, resulting in a harder martensitic microstructure. Another adjacent die element can be heated to ensure that that portion of the part being fabricated is cooled at a slower cooling rate to result in a softer microstructure, such as bainite, ferrite, and / or pearlite. Such regions of the part can remain at a higher temperature than the rest of the part when it is removed from the die.

[0014] Other methods for obtaining hot-pressed parts with regions of different mechanical properties include, for example, controlled or differential heating prior to pressing, as well as localized heat treatments after the pressing process to change the local microstructure and obtain different mechanical properties. Further possibilities include the use of patchwork blanks and tailor welded blanks (TWBs), which combine different thicknesses and / or materials in a blank.

[0015] In addition to the ultra-high strength steels mentioned above, more ductile steels can be used in portions of the structural framework that require energy absorption. Examples of ductile steels include Ductibor® 500, Ductibor® 1000, and CRL-340LA.

[0016] UHSS can exhibit high tensile strengths of 1,500 MPa or even 2,000 MPa or more, especially after press-quenching operations. After quenching, UHSS can have a martensitic microstructure. This microstructure allows for improved ultimate tensile and yield strength per unit of weight.

[0017] Some ductile steels can also be heated and pressed (i.e., can be used in hot pressing processes), but they do not have a martensitic microstructure after the process. As a result, they have lower tensile and yield strengths than UHSS, but greater elongation to failure.

[0018] While ductile steel allows for energy absorption by structural components, it may not be easy to control and predict how the structural components may behave during a vehicle crash. Furthermore, it is preferable for the overall weight of the vehicle framework to be as small as possible to reduce fuel consumption. Also, it is not easy to increase energy absorption while maintaining a certain structural integrity of the structural components.

[0019] Additionally, automobile manufacturers are increasingly using composite materials to attempt to further reduce weight.

[0020] The introduction of relatively large battery assemblies in hybrid and electric vehicles has created a need for modification of some structural components, namely those associated with the newly introduced battery assemblies. These structural components must be designed not only to accommodate the battery assemblies but also to protect against vehicle crashes and other external impacts, i.e., underfloor impacts. These structural components can be manufactured in a variety of ways and from a variety of materials. Lightweight materials that improve energy absorption during a crash while also maintaining vehicle integrity are desired.

[0021] The present disclosure aims to provide improved integration of traction batteries into the structural framework of a vehicle. Summary of the Invention

[0022] In a first aspect, a component for a vehicle frame is provided. The component includes a main frame extending longitudinally from a front end to a rear end of the vehicle frame. The main frame substantially defines a closed ring shape and includes first and second cross members and first and second transverse members. The main frame is formed by deforming a single blank.

[0023] According to this aspect, a part with a simplified manufacturing process is provided. Because the main frame is formed by deforming a single blank, manufacturing time and associated costs can be reduced. Furthermore, other post-manufacturing processes, such as welding, that may affect the mechanical properties of the part are avoided. At the same time, the provided part can have sufficient strength, rigidity, and energy absorption to provide protection to the ring-shaped central void in the event of an impact. The front and rear ends of the main frame can absorb energy in a front or rear collision, while the lateral members of the main frame can absorb energy in a side impact. The ring-shaped main frame is generally designed to transfer impact loads toward appropriate areas of the vehicle framework. Therefore, the main frame can reduce the acceleration of the vehicle due to a collision. Furthermore, the part can improve protection for other vehicle components located inside the ring shape, such as the battery assembly. Furthermore, the main frame can prevent deformation in the vehicle's inner safety zone to enhance occupant safety.

[0024] Furthermore, components according to this aspect can result in a reduction in the weight of the vehicle compared to existing counterparts, which has a direct effect on the efficiency of the vehicle, i.e., higher battery autonomy.

[0025] Throughout this disclosure, a "ring shape" may be understood as a closed shape having a central void space. This closed shape may define, among other things, a substantially rectangular perimeter, a square perimeter, or a substantially oval perimeter. Likewise, the central void space may define any suitable shape.

[0026] Furthermore, throughout this disclosure, references to "mechanical properties of a part" may be understood as the mechanical properties of the material forming that part. Thus, unless otherwise specified, comparisons of mechanical properties of parts, components, etc., are directed to the material and not to its geometry or other particularities.

[0027] Throughout this disclosure, a blank can be considered as a metal plate or sheet that is formed into a final product or semi-finished product. The blank that is formed into the main frame may in particular be a composite blank made up of several blanks or "sub-blanks" of the same or different material and / or thickness.

[0028] The sub-blank, a plurality of sub-blanks, or all of the sub-blanks may be made of hardenable steel, in particular boron steel. The thickness of the blank may typically be between 0.8 and 3 mm.

[0029] A patch can be thought of as a blank that forms a localized patch on the main frame of a part. A blank with a patch added is sometimes called a "patchwork blank" to distinguish it from a "tailor-welded blank," which is made up of at least two sub-blanks joined together by edge-to-edge welding.

[0030] Higher mechanical properties may be understood herein as higher ultimate tensile strength and / or higher yield strength, while lower mechanical properties may be understood herein as lower ultimate tensile strength and / or lower yield strength. Ultimate tensile strength and yield strength are considered herein as material properties of the material after the manufacturing process. Ultimate tensile strength and yield strength can be determined by standard tensile strength tests, for example, using A30, A50, or A80 test specimens in quasi-static loading tests.

[0031] Comparisons between lower and higher mechanical properties should be made using the same test conditions and specimen size. To compare the yield strength of different parts, specimens can be created and tested on a universal testing machine (UTM).

[0032] In some examples, the mainframe may be fabricated by hot pressing, and thus may have at least some of the advantages of parts fabricated by this manufacturing process previously disclosed.

[0033] In some examples, a single blank (a "composite blank") formed into the main frame includes at least two sub-blanks that form one or more overlap regions. The overlap regions may be formed by partially overlapping two sub-blanks. In some examples, at least one of the overlap regions is located in a portion of the main frame configured to be connected to other components of the vehicle framework, i.e., the overlap is positioned in an area of ​​the composite blank so that it will be located in the appropriate portion of the main frame after deformation. The mechanical strength and stiffness of the overlap region may be higher than the rest of the main frame due to the increased thickness where the sub-blanks overlap. Providing overlap regions in areas used for joining to other portions of the vehicle framework promotes a robust connection between the components, especially when the connection is configured to transfer loads between the components.

[0034] In a further example, the overlap region may be formed at the transition between the lateral member and the rear cross member.

[0035] Furthermore, by using suitable materials, the main frame can be given suitable properties in terms of crash behavior and weight reduction, for example by using patch welding, whereby welding a first patch to the main frame reinforces the main frame as needed without adding additional undesirable weight.

[0036] In some instances, a patchwork blank can have an overlap of soft (or "ductile") and hard material in areas that would withstand compressive or bending forces in a crash situation. In these areas, the part can withstand greater deformation (e.g., greater bending angles) without risk of fracture, making the vehicle safer.

[0037] Typically, the patch is welded to the main piece by spot welding, a welding technique well known and widely used in the automotive field. The overlapping sub-blanks may also be connected by spot welding.

[0038] In some examples, a single blank can include a tailor-welded blank that includes at least two sub-blanks of different thicknesses or materials. In some examples, one or more of the sub-blanks that together form a composite blank can be a tailor-welded blank. The sub-blanks can include materials with different mechanical properties to tailor the strength, stiffness, and deformation characteristics of the main frame.

[0039] In some examples, at least a portion of the main frame, i.e., the cross members and / or transverse members, may be made of steel having an ultimate tensile strength of more than 1500 MPa after a press-hardening process.

[0040] In some examples, at least a portion of the main frame can have a substantially U-shaped cross section. The U-shaped cross section includes a bottom wall, a first side wall, a second side wall, a first lateral flange projecting outward at an end of the first side wall, and a second lateral flange projecting outward at an end of the second side wall. The portion having the U-shaped cross section can be a portion of a member, i.e., a portion of a cross member, or a portion extending across several members.

[0041] A U-shaped cross section provides rigidity to the main frame, is easy to manufacture, and provides convenient areas, i.e., flanges, for connection to other structural elements. Throughout this disclosure, a U-shaped cross section may be understood to refer to a structural member having, in cross section (generally, a transverse plane substantially perpendicular to the longitudinal axis of the structural member), a bottom wall and two side walls. U-shaped cross sections are generally known for their favorable moment of inertia to weight ratio. The two side walls may form an obtuse angle with the bottom wall, for example, between 90° and 135°. The two side walls may include outwardly extending lateral flanges. The bottom wall and side walls may be substantially straight, but may also include transitions, curves, recesses, or protrusions.

[0042] In some examples, the main frame may be configured to receive the battery assembly in a central empty space of the ring shape. Further, in some examples, the cross member includes a central region between the front end and the rear end, the central region being configured to connect to the battery assembly. In this manner, the main frame can provide support and protection for the battery assembly of the vehicle.

[0043] In some examples, the cross members are configured to be connected at their front and rear ends to front and rear rails of the vehicle frame, respectively.

[0044] In some examples, each cross member is configured to connect to a side rocker of the vehicle frame, and the connection may be horizontal, i.e., the cross member and the side rocker are horizontally side-by-side, or vertical, i.e., the cross member is substantially above the rocker, or vice versa.

[0045] The components of the present disclosure may be part of the vehicle framework, i.e., part of the vehicle's body-in-white.

[0046] In some examples, the battery assembly (battery box or tray, battery cells, cover, etc.) can be connected to the component. The connection between the battery assembly and the main frame of the component may be performed after joining the component to the rest of the vehicle framework. The connection between the battery assembly may be direct, i.e., using a fastener assembly, or may use an intermediate component.

[0047] In a further aspect, a method is provided for manufacturing a component for a vehicle frame, the component comprising a main frame substantially defining a closed ring shape, the main frame comprising first and second cross members and first and second transverse members.

[0048] The method includes providing a single blank, heating the single blank above an Ac3 austenitizing temperature, and press-quenching the heated single blank to form a part.

[0049] The method provides a simpler yet more efficient way of manufacturing parts compared to known techniques. Furthermore, the resulting parts can be lighter in weight compared to parts of similar mechanical properties manufactured using other methods. Furthermore, the resulting parts can have better deformation behavior, and the method can make it possible to tailor the deformation profile of the part, for example, during a car crash, thus increasing energy absorption and overall vehicle safety.

[0050] In some examples of the method, the single blank comprises at least two sub-blanks, and the method further includes joining the sub-blanks to one another. The joining step may include partially overlapping the two sub-blanks to form one or more overlapping regions.

[0051] Non-limiting examples of the present disclosure are described below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0052] [Figure 1] 1 is a schematic diagram illustrating a perspective top view of an example of a vehicle part. [Figure 2] 2 shows a schematic top view of the components of FIG. 1; [Figure 3] 2 shows a schematic side view of the component of FIG. 1; [Figure 4] 10A and 10B are schematic perspective top views of another example of a part for a vehicle; [Figure 5] 5 shows a schematic cross section of the part across the plane AA of FIG. 4. [Figure 6] 2 shows another example of a part in a vehicle framework, in a schematic manner; [Figure 7] 10 shows a schematic representation of a single blank prior to forming another example of a part. [Figure 8] 1 is a flowchart of a method for manufacturing a part. DETAILED DESCRIPTION OF THE INVENTION

[0053] The figures refer to exemplary embodiments and are used only as an aid in understanding the claimed subject matter and are not intended to limit the claimed subject matter in any way.

[0054] 1 illustrates a schematic perspective top view of an example of a component for a vehicle frame. The component comprises a main frame 100 extending longitudinally of the vehicle frame from a front end 200 to a rear end 300. The main frame substantially defines a closed ring shape and comprises a first cross member 110, a second cross member 120, a first cross member 130, and a second cross member 140. Furthermore, the main frame 100 is made by deforming a single blank.

[0055] 1 and 2, the first and second cross members 110, 120 extend generally along the longitudinal direction of the vehicle frame. The first and second cross members extend generally transversely, i.e., substantially horizontally and substantially perpendicular to the longitudinal direction of the vehicle frame.

[0056] The example mainframe 100 shown in FIG. 1 can be manufactured by hot pressing. For example, it can be manufactured by a direct hot pressing manufacturing process or an indirect hot pressing manufacturing process. In other examples, the mainframe 100 can be manufactured by cold pressing or other manufacturing processes. Further details regarding the manufacturing process of the part are described in connection with FIG. 5.

[0057] The component's main frame 100 can have at least a portion with a substantially U-shaped cross-section. The U-shaped cross-section can have a bottom wall, a first side wall, a second side wall, a first lateral flange projecting outward at an end of the first side wall, and a second lateral flange projecting outward at an end of the second side wall. The lateral flanges provide convenient attachment points, for example, by riveting or spot welding, to connect the main frame 100 to other parts of the vehicle, such as other components of the vehicle's structural frame. When attached to the vehicle frame, the U-shape can face substantially upward, i.e., the bottom wall is at the bottom and the open side of the U is at the top.

[0058] Additionally, the bottom wall may be substantially perpendicular to the side walls. In a further example, the bottom wall may subtend an angle other than 90 degrees with respect to the side walls. The radius of curvature between the bottom wall and the side walls may be adjusted according to the specifications of the main frame 100, i.e., the mechanical properties of the materials used, the desired maximum local strength, etc. The radius of curvature between the side walls and the lateral flanges may also vary depending on the specifications of the main frame 100, as previously described.

[0059] Figures 2 and 3 show top and side views, respectively, of the exemplary components of Figure 1. These figures show that the main frame 100 can be configured to receive a battery assembly in the ring-shaped central void 150.

[0060] Additionally, in some examples, the main frame 100 can include cross members 110, 120 having central regions 111, 121 between the front end 200 and the rear end 300 configured to connect to a battery assembly (not shown). A battery tray or box can be connected to the main frame 100 via one or more brackets. For example, the battery assembly can be connected to each of the cross members using two brackets.

[0061] Additionally, the component main frame 100 may include one or more soft zones (not shown) that have lower mechanical properties than other zones of the main frame 100. The soft zones may span specific areas of the main frame 100 to absorb energy in the event of an impact and limit the degree of intrusion in other zones of the main frame 100. Thus, components with different mechanical properties may be provided at different locations on the main frame 100 to improve battery and occupant safety.

[0062] In some examples, the outer sidewall of the cross member may include a soft zone so that it can absorb energy in a side impact and protect the battery assembly.

[0063] In certain instances, the portion of the main frame joined to the rear rail may be more ductile than other portions. In some instances, the soft zone may span a portion of the cross member, such as 5-20% of the length of the cross member.

[0064] The soft zones may have a yield strength between 600 and 950 MPa, particularly between 650 and 800 MPa. Furthermore, the main frame 100 of the component may have an ultimate tensile strength (outside of the soft zones) of primarily 1,000 MPa or more, particularly 1,200 MPa or more, more particularly 1,500 MPa or more.

[0065] The main frame 100 may have a transition zone, ie a zone between the soft zone and the rest of the main frame 100, having a width smaller than 30 mm, specifically between 20 mm and 5 mm.

[0066] In some examples, the mainframe 100 may be made of boron steel such as Usibor®, for example Usibor® 1500 (22MnB5 steel with or without a protective coating) or Usibor® 2000 (37MnB5), or any martensitic or ultra-high strength steel (UHSS). Usibor® is commercially available from ArcelorMittal.

[0067] Usibor® 1500 is supplied in the ferrite-pearlite phase. This is a fine grain structure distributed in a homogeneous pattern. Its mechanical properties are related to this structure. After heating, a hot pressing process, and subsequent quenching, a martensitic microstructure is produced. The result is a significant increase in tensile strength and yield strength.

[0068] The composition of Usibor® 1500 is summarized below in weight percent (the remainder is iron (Fe) and impurities): Maximum carbon (C) (%): 0.25 Maximum silicon (Si) (%): 0.4 Maximum manganese (Mn) (%): 1.4 Maximum phosphorus (P) (%): 0.03 Maximum sulfur (S) (%): 0.01 Aluminum (Al) (%): 0.01 to 0.1 Maximum Titanium (Ti) (%): 0.05 Maximum Niobium (Nb) (%): 0.01 Maximum copper (Cu)(%):0.20 Maximum boron (B) (%): 0.005 Maximum Chromium (Cr) (%): 0.35

[0069] Usibor® 2000 is another boron steel, 37MnB5, that has even higher strength. After the hot press die quench process, the yield strength of Usibor® 2000 can be 1300 MPa or greater, and the ultimate tensile strength can be greater than 1800 MPa.

[0070] The composition of Usibor® 2000 is summarized below in weight percent (the remainder is iron (Fe) and impurities): Maximum carbon (C) (%): 0.36 Maximum silicon (Si) (%): 0.8 Maximum manganese (Mn) (%): 0.8 Maximum phosphorus (P) (%): 0.03 Maximum sulfur (S) (%): 0.01 Aluminum (Al) (%): 0.01 to 0.06 Maximum Titanium (Ti) (%): 0.07 Maximum Niobium (Nb) (%): 0.07 Maximum copper (Cu)(%):0.20 Maximum boron (B) (%): 0.005 Maximum Chromium (Cr) (%): 0.50 Maximum Molybdenum (Mb) (%): 0.50

[0071] 22MnB5 and other boron steels may be coated with an aluminum-silicon coating to prevent decarburization and scale formation during the forming process. Several 22MnB5 steels with similar chemical compositions are commercially available. However, the exact amounts of each component in 22MnB5 steel may vary slightly from manufacturer to manufacturer. Other ultra-high strength steels include BTR 165, available from Benteler.

[0072] In some examples, mainframe 100 may include members made of different materials. For example, mainframe 100 may include cross members 110, 120 made of a first UHSS (e.g., Usibor® 1500 or 22MnB5) and first and second cross members 130, 140 made of another UHSS (e.g., Usibor® 2000 or 37MnB5). The other materials for each member may be selected to form parts with given dynamic responses and mechanical properties.

[0073] 3 shows that the front end 200 and rear end 300 of the component's main frame 100 may be at different heights relative to the central region 121 of the cross member 120. Accordingly, the main frame 100 may include a front transition region 201 and a rear transition region 301 to provide a height transition between the different regions of the main frame 100. In the illustrated illustration, the front transition region 201 exhibits a steeper transition than the rear transition region 301. However, in other examples, this characteristic may be reversed. The radii of curvature of these transition regions 201, 301 may be configured to tailor the distribution of stress in the event of an impact.

[0074] Figures 4 and 5 show another example of a component according to the present disclosure: Figure 4 is a perspective view of the main frame 100 of the component, and Figure 5 shows a cross section of the component across plane AA of Figure 4.

[0075] In the example shown in FIGS. 4 and 5, the main frame 100 can include two or more sub-blanks 101, 102 that, when formed, obtain a substantially L-shaped cross-section. Furthermore, as can be better seen in FIG. 5, the two sub-blanks 101, 102 can cooperate to define a substantially U-shaped cross-section. Accordingly, the two or more sub-blanks 101, 102 can define an overlap region 19 at the bottom of the U-shaped cross-section. It is apparent that the sub-blanks 101, 102 can be joined together when both are substantially flat sheets, i.e., one sub-blank can be positioned to overlap the other, and the sub-blanks can then be joined, for example, by welding. Once joined together (and optionally after being joined to additional sub-blanks), the combined blanks can be deformed to obtain the illustrated ring-shaped member having a U-shaped cross-section.

[0076] Each of the two or more sub-blanks 101, 102 may be made of a different material. For example, the sub-blank 101 designed to be located on the outside of the U-shaped cross-section (relative to the central void 150) may be made of a UHSS (e.g., a boron steel such as 22MnB5 or similar steel), and the sub-blank 102 designed to be located on the inside of the U-shaped cross-section may be made of a more ductile steel (e.g., Ductibor® 1000 or similar steel).

[0077] Ductibor® is a steel material that has much higher ductility than Usibor® material, and parts made from this material can be more effective at absorbing energy during impact. The yield strength of Ductibor® 500 can be 400 MPa or greater, and the ultimate tensile strength can be 550 MPa or greater.

[0078] The composition of Ductibor® 500 is summarized below in weight percent (the remainder is iron (Fe) and impurities): Maximum carbon (C) (%): 0.1 Maximum silicon (Si) (%): 0.5 Maximum manganese (Mn) (%): 1.7 Maximum phosphorus (P) (%): 0.03 Maximum sulfur (S) (%): 0.025 Aluminum (Al) (%): 0.015 to 0.2 Maximum Titanium (Ti) (%): 0.09 Maximum Niobium (Nb) (%): 0.10 Maximum copper (Cu)(%):0.20 Maximum boron (B) (%): 0.001 Maximum Chromium (Cr) (%): 0.20

[0079] The yield strength of Ductibor® 1000 may be 800 MPa or greater and the ultimate tensile strength may be 1000 MPa or greater. The composition of Ductibor® 1000 is summarized below in weight percent (the remainder is iron (Fe) and impurities): Maximum carbon (C) (%): 0.10 Maximum silicon (Si) (%): 0.6 Maximum manganese (Mn) (%): 1.8 Maximum phosphorus (P) (%): 0.03 Maximum sulfur (S) (%): 0.01 Aluminum (Al) (%): 0.01 to 0.1 Maximum Titanium (Ti) (%): 0.05 Maximum Niobium (Nb) (%): 0.10 Maximum copper (Cu)(%):0.20 Maximum boron (B) (%): 0.005 Maximum Chromium (Cr) (%): 0.20

[0080] In some instances, the two sub-blanks 101, 102 may be joined by spot welding prior to the forming process.

[0081] 4 and 5, the two sub-blanks 101, 102 extend along the entire periphery of the mainframe 100; however, in other examples, a component may include a mainframe 100 in which the sub-blanks do not extend along the entire length of the mainframe 100. For example, the mainframe 100 may include a first cross member 130 (as cross member 130 in FIG. 1) formed by overlapping a first blank made of Ductibor® with a second blank made of Usibor® to define a U-shaped cross section. This cross member may then be joined to the remainder of the mainframe 100 via an additional overlap region. Additionally, the remainder of the mainframe 100 may be formed from a single sub-blank or multiple sub-blanks.

[0082] 6 shows a schematic diagram from a bottom isometric perspective of another example of components coupled to a vehicle frame 1000. The illustrated vehicle frame 1000 includes front rails 31, rear rails 41, and components of the present disclosure including a main frame 100. In other examples, the vehicle frame 1000 can further include vehicle floor and side structures or other components.

[0083] As previously disclosed, the main frame 100 may be configured to receive the battery assembly 50. The battery assembly 50 may be housed in the ring-shaped central empty space. Furthermore, the cross members 110, 120 of the main frame 100 may be configured to connect to the front rail 31 and the rear rail 41 at the front end 200 and the rear end 300 of the vehicle framework 1000, respectively. In some examples, the main frame 100 may be welded to the front rail 31 and the rear rail 41.

[0084] Additionally, the cross members 110, 120 may be configured to connect to side rockers (not shown) of the vehicle framework 1000. This connection may occur at various points along their length. In some examples, the connections between the cross members 110, 120 and the side rockers occur at substantially forward and aft locations, i.e., more centrally relative to the connections to the front rail 31 and rear rail 41, respectively.

[0085] It should be noted that regions of the main frame 100 configured to be connected to other structural elements of the vehicle framework 1000 may have suitable mechanical properties to achieve a secure and rigid bond. These regions may include materials with different mechanical properties than the rest of the main frame 100, such as soft zones or metal patches. Also, certain overlapping regions of the sub-blank may be formed in these regions to increase the local thickness.

[0086] 6, the components may include one or more additional members attached to the main frame 100. The additional members may be covers, plates, or structural components similar to the main frame 100.

[0087] FIG. 7 schematically illustrates a blank 10 prior to forming a ring-shaped main frame according to a further example. The blank 10 can include at least two sub-blanks, each of which forms one or more overlapping regions by partially overlapping two sub-blanks. In the example shown in FIG. 7, the single blank 10 includes eight sub-blanks 11, 12, 13, 14, 15, 16, 17, and 18. In this example, each of the sub-blanks 11, 12, 13, 14, 15, 16, 17, and 18 can be formed from the same material, such as boron steel. The sub-blanks can be formed from Usibor® 2000 or Usibor® 1500, but in other examples, they can be formed from different materials such that the mechanical properties of the main frame after formation can be substantially different.

[0088] Additionally, in other examples, one or more sub-blanks may be formed from a material having a substantially homogeneous composition, but may be subjected to heat treatment after formation such that the mechanical properties of each component are not homogeneous. Thus, a sub-blank may include a first portion having higher mechanical properties than a second portion. Furthermore, the first portion may be configured to withstand high impact loads, and the second portion may include connection points to the main frame 100 or other components of the vehicle framework.

[0089] Additionally, FIG. 7 illustrates that a single blank 10 includes multiple overlap regions 19. The overlap regions 19 may be located where the main frame 100 requires higher mechanical properties to withstand loads acting on the main frame 100. The length and shape of the overlap regions 19 may be designed to cover only those locations where higher loads may exist. Additionally, the overlap regions 19 may be designed to cover areas where the cross section transitions from one member to another, such as the area between a cross member and a transverse member. In the example shown in FIG. 7, the overlap regions 19 represent the transitions between transverse members, such as the transitions between the cross member 14 and the transverse members 15 and 13. Additionally, the overlap regions 19 may be shaped and dimensioned to improve the overall strength of the main frame 100 (see FIG. 1) without incurring excessive weight.

[0090] In some examples, the first sub-blank may extend over the second sub-blank by a length between 2 and 30 cm.

[0091] Additionally, by properly selecting and providing overlap area 19, internal brackets between main frame 100 and other components of the vehicle can be eliminated or reduced.

[0092] Additionally, the overlapping region 19 can improve the rigidity of the connection of the main frame 100 with other components, such as battery module fixtures. In the example of Fig. 7, the cross member 12 includes connection points 125 for the battery module fixtures that are at least partially located in the overlapping region 19. Furthermore, the cross members 11, 12 include connection points 115 for chassis fastening that are at least partially located within the overlapping region 19.

[0093] Additionally, the overlap region 19 can be designed to provide improved NVH (noise, vibration, and harshness) performance, particularly around the main frame connection points 115 with the front and rear chassis.

[0094] Note that the connection points 125, 115 are shown on only one side of the single blank 10. The connection points 125, 115 may be symmetrically disposed on the single blank 10 about the central longitudinal axis 1. In other examples, the connection points 125, 115 may not be symmetrical about the central longitudinal axis 1.

[0095] In other examples, patches (not shown) may be included on the sub-blank, i.e., by overlapping the patch onto the sub-blank and spot welding. As previously mentioned, two or more patches may be welded to a single blank 10 prior to pressing.

[0096] Furthermore, at least some of the sub-blanks 11, 12, 13, 14, 15, 16, 17, 18 may have a thickness between 0.8 and 3 mm, in particular between 1 and 2.5 mm.

[0097] In some examples, other suitable steels can be used, such as any steel suitable for hot or cold pressing. In some examples, blanks or sub-blanks, such as transverse and / or cross members, may be fabricated from dual-phase (DP) steels. DP steels are high-strength steels with a ferrite-martensite microstructure obtained by quenching a part from a temperature higher than Ac1 but lower than Ac3. DP steels include a microstructure consisting of a matrix of soft ferrite with islands of martensite. Parts made from DP steels can have ultimate tensile strengths of less than 900 MPa, relatively good fatigue resistance, and high strain rate sensitivity, i.e., they collapse faster and absorb more energy in the event of an impact.

[0098] Additionally, other steels that exhibit high formability combined with high strength can also be used to manufacture (portions of) the main frame 110 by cold forming processes. Components such as horizontal and / or cross members made from Fortiform® can offer additional weight savings compared to components made from DP steel with similar mechanical properties. Fortiform® steel is commercially available from ArcelorMittal.

[0099] In some examples, the main frame 110 can be fabricated from Fortiform®, for example, the main frame 110 can be fabricated from Fortiform® 1180 (HF1180Y850), which has a tensile strength of 1180-1330 MPa. In other examples, the main frame 110 can be fabricated from Fortiform® S1270, which has a tensile strength of 1270-1400 MPa. In further examples, the main frame 110 can include components fabricated from Fortiform® 1180 and components fabricated from Fortiform® S1270. Additionally, the components of the main frame 110 made from Fortiform® can be welded together using conventional welding processes, such as spot welding.

[0100] The composition of Fortiform® 1180 is summarized below in weight percent (the remainder is iron (Fe) and impurities): Maximum carbon (C) (%): 0.23 Maximum silicon (Si) (%): 2.0 Maximum manganese (Mn) (%): 2.9 Maximum phosphorus (P) (%): 0.040 Maximum sulfur (S) (%): 0.010 Aluminum (Al) (%): 0.015 to 1.0 Maximum titanium + niobium (Ti + Nb) (%): 0.15 Maximum Niobium (Nb) (%): 0.10 Maximum copper (Cu)(%):0.20 Maximum boron (B) (%): 0.005 Maximum Chromium + Molybdenum (Cr+Mo)(%): 0.60

[0101] The composition of Fortiform® S1270 is summarized below in weight percent (the remainder is iron (Fe) and impurities): Maximum carbon (C) (%): 0.21 Maximum silicon (Si) (%): 1.5 Maximum manganese (Mn) (%): 4.1 Maximum phosphorus (P) (%): 0.04 Maximum sulfur (S) (%): 0.01 Aluminum (Al) (%): 0.015 to 1.0 Maximum titanium + niobium (Ti + Nb) (%): 0.15 Maximum Niobium (Nb) (%): 0.10 Maximum copper (Cu)(%):0.2 Maximum Chromium + Molybdenum (Cr+Mo)(%): 0.6

[0102] Steels suitable for hot and cold forming having other material compositions may also be used to manufacture at least some of the components of the disclosed main frame 110.

[0103] In another aspect of the present disclosure, a method 400 is provided for manufacturing a component for a vehicle framework comprising a main frame 100. The main frame 100 substantially defines a closed ring shape and comprises first and second cross members 110, 120 and first and second transverse members 130, 140.

[0104] An example of a method 400 is shown generally in Figure 8. The method 400 includes, at block 401, providing a single blank 10. The method 400 further includes, at block 402, at least partially heating the single blank 10 above an Ac3 austenitizing temperature. The method 400 further includes, at block 403, press-quenching the heated single blank 10 to form a part.

[0105] In some examples, as previously mentioned, the single blank 10 may be made of hardenable steel, and the soft zones can be created by controlled cooling in the mold as the part is formed, or by application of heat after the part is formed.

[0106] In some examples, the single blank 10 of method 400 can include at least two sub-blanks 11, 12, 13, 14, 15, 16, 17, 18, and method 400 can further include joining the sub-blanks 11, 12, 13, 14, 15, 16, 17, 18 to one another. The step of joining the sub-blanks 11, 12, 13, 14, 15, 16, 17, 18 can include forming one or more overlap regions 19 by partially overlapping two sub-blanks 11, 12, 13, 14, 15, 16, 17, 18.

[0107] In some examples, the single blank 10 of the method 400 may include a tailored welded blank that includes at least two sub-blanks 11, 12, 13, 14, 15, 16.

[0108] The single blank 10 can be made from any type of hardenable steel, particularly boron steel, as previously described for the main frame 100.

[0109] The heating step 402 of the method 400 may include substantially uniformly heating the single blank 10 above the austenitizing temperature and then cooling a portion of the single blank 10 specifically below the austenitizing temperature.

[0110] In some examples, a single blank 10 can be heated above Ac3, and a portion of the single blank 10 can be cooled to a temperature below Ac3 or even below Ac1 before deforming the blank 10. Other portions can be maintained above Ac3 until the blank 10 is deformed, or can be cooled briefly and then heated again above Ac3.

[0111] In some instances, when the blank 10 is placed in the press tool, different portions of the blank 10 may have different temperatures, although the temperature within these locations is substantially constant.

[0112] Thus, different temperatures can result in different microstructure or strength property settings in each portion of mainframe 100, especially upon subsequent rapid cooling ("quenching"), for example, in the mold of a press tool.

[0113] In some examples, the composite blank 10 is quenched to below 400°C, particularly below 300°C, while being formed in a press-quench step 403 to form the main frame 100.

[0114] In some examples, the method 400 can further include the step of bake hardening the part 100. In bake hardening, the part can be heated to 170-200 degrees Celsius, more specifically, about 170 degrees Celsius, for about 20 minutes.

[0115] While only a few examples are disclosed herein, other alternatives, modifications, uses, and / or equivalents are possible. Moreover, all possible combinations of the described examples are also covered. Accordingly, the scope of the present disclosure should not be limited by the specific examples, but should be determined solely by a fair study of the appended claims.

Claims

1. A component for the vehicle's frame, The main frame of the aforementioned vehicle extends from the front end to the rear end along the longitudinal direction of the vehicle's framework. Equipped with, The main frame substantially defines a closed ring shape and is configured to receive a battery assembly in the central open space of the closed ring shape. The main frame comprises first and second transverse members that extend substantially along the longitudinal direction of the vehicle's frame, and first and second transverse members that extend substantially horizontally and perpendicular to the longitudinal direction of the vehicle's frame. The aforementioned main frame is a component formed by deforming a single blank.

2. The main frame is manufactured by hot pressing, as described in claim 1.

3. The component according to claim 1, wherein the single blank comprises at least a first subblank, the first subblank being joined to the second subblank such that it partially overlaps the second subblank to form an overlapping region.

4. The component according to claim 3, wherein the overlapping region is located in a portion of the main frame configured to connect to other components of the vehicle's framework.

5. The component according to claim 3, wherein the first subblank extends on the second subblank for a length of at least 1 cm, and more particularly between 2 and 30 cm.

6. The part according to claim 1, wherein the single blank comprises a tailor-welded blank including at least two subblanks joined to each other at their edges.

7. The component according to claim 1, wherein at least a portion of the main frame is made of steel having an ultimate tensile strength of more than 1500 MPa after a press-quenching process.

8. At least a portion of the main frame has a substantially U-shaped cross-section, The component according to claim 1, wherein the U-shape comprises a bottom wall, a first side wall, a second side wall, a first transverse flange projecting outward at the end of the first side wall, and a second transverse flange projecting outward at the end of the second side wall.

9. The component according to claim 1, wherein the transverse member has a central region between the front end and the rear end, and the central region is configured to be connected to the battery assembly.

10. The component according to claim 1, wherein the transverse member is configured to be connected to the front rail and rear rail of the vehicle's frame at its front end and rear end, respectively.

11. The component according to claim 1, wherein each lateral member is configured to be connected to the side rocker of the vehicle's frame.

12. The component according to claim 1, wherein the main frame comprises a soft zone having lower yield strength and / or tensile strength than the rest of the main frame.

13. A method for manufacturing a component for a vehicle frame, comprising a main frame, the main frame substantially defining a closed ring shape, and configured to receive a battery assembly in a central open space formed inside the closed ring shape, the main frame comprising first and second transverse members and first and second cross members, To prepare a single blank, The single blank is heated to at least partially above the Ac3 austenitizing temperature, The heated single blank is press-quenched to form the part according to any one of claims 1 to 12. A method that includes this.

14. The method according to claim 13, wherein the single blank comprises at least two subblanks, and the method includes joining the subblanks to each other before press hardening.

15. The method according to claim 14, wherein joining the subblanks includes forming one or more overlapping regions by partially overlapping two subblanks.

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