Integrated roof ring for vehicle frame

Abstract

The present disclosure relates to a method for manufacturing an integrated roof ring (100) of a vehicle frame. The method comprises: providing a plurality of blanks (1, 2, 3, 4); joining the blanks to each other to form a bonded blank (5); and deforming the bonding blank (5) to form the integrated roof ring (100). The integrated roof ring (100) comprises two rail portions (10, 20), each connected to a front cross member (30) and a rear cross member (40) to form a substantially closed ring shape. The present disclosure further relates to an integrated roof ring obtainable by such a method.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of European patent application No. 22383193.4 filed on December 7, 2022. Technical Field

[0003] The present disclosure relates to an integrated roof hoop for a vehicle and a method of manufacturing the same. Background Art

[0004] Vehicles such as automobiles incorporate a structural framework designed to withstand all loads that the vehicle may experience during its service life. The structural framework is further designed to withstand and absorb impacts in the event of a collision, such as with other cars, obstacles, or pedestrians.

[0005] The structural framework of a vehicle (eg, a car) in this sense may include, for example, bumpers, pillars (A-pillars, B-pillars, C-pillars, D-pillars), side impact beams, rocker or sill beams, hinge pillars, and shock absorbers.

[0006] Press quenching, also known as hot forming die quenching (HFDQ), typically uses boron steel sheets to produce stamped parts with the characteristics of ultra-high strength steel (UHSS), with a tensile strength of, for example, 1500 MPa or 2000 MPa, or even higher. The increased strength allows the use of thinner gauge material, which saves weight compared to conventional cold stamped mild steel parts. Throughout this disclosure, UHSS can be considered to be steel with an ultimate tensile strength of 1000 MPa or higher, especially after the press hardening process.

[0007] In the HFDQ process, the blank to be hot-formed can be heated to a predetermined temperature, such as the austenitizing temperature or higher (and in particular, between Ac3 and, for example, the evaporation temperature of the blank's coating). For this purpose, a high-temperature furnace system can be used. Depending on specific needs, the high-temperature furnace system can be supplemented with additional heaters, such as induction heaters or infrared heaters. By heating the blank, its strength is reduced and its deformability is increased, facilitating the hot stamping process.

[0008] There are several known ultra high strength steels (UHSS) for hot stamping and hardening. The blank to be hot formed may be made of, for example, coated or uncoated boron steel, such as commercially available from ArcelorMittal. (22MnB5).

[0009] Typical vehicle components that can be manufactured using the HFDQ process include door beams, bumper beams, cross / side beams, A / B pillar reinforcements, front and rear longitudinal beams, seat cross beams, and roof rails.

[0010] Hot forming of boron steels is becoming increasingly popular in the automotive industry due to their excellent strength and formability. As a result, many structural components traditionally cold-formed from mild steels are being replaced with hot-formed equivalents, which significantly increase strength. This allows for a reduction in material thickness (and therefore weight) while maintaining the same strength.

[0011] In order to improve the ductility and energy absorption of specific areas of a component, it is known to introduce softer areas within the same component. This improves ductility locally while maintaining the desired high strength overall. By locally tailoring the microstructure and mechanical properties of certain structural components so that they include areas with very high strength (very hard) (i.e., areas with high ultimate tensile strength and high yield strength), areas of increased ductility (softer) (i.e., areas with lower ultimate tensile strength and lower yield strength), and areas of increased elongation before fracture, it may be possible to improve overall energy absorption and maintain their structural integrity during a crash situation, while also reducing their overall weight. Such soft areas can also advantageously alter the kinematic behavior in the event that the component collapses under impact.

[0012] A known method for producing regions of increased ductility ("soft zones") in structural components of vehicles includes providing a tool comprising a pair of complementary upper and lower die units, each of which has a separate die element (steel block). The blank to be hot-formed is preheated to a predetermined temperature, such as the austenitizing temperature or higher, by, for example, a high-temperature furnace system, in order to reduce the strength, i.e., to facilitate the hot stamping process.

[0013] Die elements can be designed to operate at different temperatures so that different regions of the part being formed experience different cooling rates during the quenching process, thereby producing different material properties in the final product, such as a soft zone that typically has lower ultimate tensile strength and yield strength but allows for greater elongation before fracture. For example, one die element can be cooled to quench a corresponding region of the part being manufactured at a high cooling rate, thereby rapidly reducing the part's temperature and achieving a hard martensitic microstructure. Another adjacent die element can be heated to ensure that the corresponding portion of the manufactured part cools at a lower cooling rate, resulting in a softer microstructure, including, for example, bainite, ferrite, and / or pearlite. This region of the part can remain at a higher temperature than the rest of the part as it exits the die.

[0014] Other methods for obtaining hot stamped parts with different mechanical properties include, for example, customized or differential heating before stamping and local heat treatment after the stamping process to change the local microstructure and obtain different mechanical properties. Further possible methods include the use of patchwork blanks (patchwork blanks) and tailor welded blanks (TWBs) that combine different thicknesses and / or materials in the blank.

[0015] UHSS can exhibit tensile strengths as high as 1500 MPa, or even 2000 MPa or higher, particularly after a press-hardening operation. Once hardened, UHSS can have a martensitic microstructure. This microstructure can increase the maximum tensile strength and yield strength per unit weight.

[0016] In addition to the ultra-high-strength steels mentioned above, more ductile steels can also be used in the parts of the structural skeleton that need to absorb energy. These steels can be used in the hot stamping process, but the martensitic microstructure will not be obtained in this process. 1000 is an example of a suitable more ductile steel.

[0017] The upper frame of a vehicle's structural framework can be formed by connecting multiple structural components. These structural components form the roof ring, which is one of the structures that protects the vehicle in the event of a collision. A vehicle's roof ring typically includes four beams: two longitudinal beam sections (commonly referred to as roof rails) and front and rear cross beams (commonly referred to as front and rear header beams). The roof rails are located between the vehicle's A-pillars and C-pillars. The front header beam is located between the A-pillars, and the rear header beam is located between the C-pillars. In the event of a collision, the roof ring plays a vital role in ensuring the integrity of the vehicle.

[0018] The four rails that make up the roof ring can have different thicknesses and be manufactured differently. The roof rails and front header are components with a high desired stiffness (typically achieved through hot stamping ("press hardening")) and are intended to limit intrusion in the event of a relatively low-weight impact. The rear header is typically made of a material suitable for cold stamping. After manufacturing these four rails, they are typically welded together when assembled with the rest of the vehicle frame or "body in white."

[0019] One issue that has been encountered is the number of welds and seams that can make parts vulnerable in a crash. Other issues that need to be considered are weight, manufacturability, the time required to build the vehicle, and the cost.

[0020] The present disclosure provides examples of systems and methods that provide improvements to prior art roof structures. Summary of the Invention

[0021] In a first aspect, a method for manufacturing an integrated roof ring for a vehicle structural frame is provided. The method comprises providing a plurality of blanks; joining the blanks to form a joined blank; and deforming the joined blank to form an integrated roof ring, wherein the integrated roof ring comprises two longitudinal beam portions, each longitudinal beam portion being connected to a front cross beam and a rear cross beam to form a substantially closed ring.

[0022] Deforming the bonded blank after joining the blanks together to form a bonded blank provides a lightweight and durable roof ring constructed in a minimal number of steps. Joining the blanks before deformation enables the production of a roof ring with no or minimal heat-affected zone, as post-forming welding operations are reduced. A reduced heat-affected zone reduces the risk of cracks forming in the upper frame of the structural framework in the event of a crash. This allows the strength of the roof ring to be increased while reducing the thickness of the blanks and reducing weaknesses in the final ring. Consequently, crash performance can be improved while simultaneously reducing the mass of the vehicle's upper frame, which can reduce the thickness of adjacent components of the roof ring.

[0023] In some examples, the plurality of blanks include a front transverse beam blank, two longitudinal beam blanks, and a rear transverse beam blank. In some examples, the plurality of blanks may be made of ultra-high strength steel (UHSS), and one or more of the blanks may be made of boron steel.

[0024] In some examples, blanks from different material thicknesses and / or grades may be used in order to meet specific strength, intrusion resistance, and energy absorption requirements and to optimize weight.

[0025] In some examples, joining the blanks includes forming one or more overlapping regions formed by partially overlapping the blanks with each other. In the present disclosure, partially overlapping two blanks means that only a portion of the two blanks overlap.

[0026] The one or more overlapping regions may be arranged to counteract material reduction, and resulting strength reduction, that may occur in some cross sections of the integral roof ring when compared to a solution in which structural components are first formed and then joined to form the upper structural frame.

[0027] Alternatively or additionally, the overlap may be arranged in locations where high loads are expected, for example by arranging patch blanks within blanks.

[0028] Throughout this disclosure, the front and rear transverse beam blanks may be considered to be blanks that are subsequently deformed to form the front and rear cross beams of the roof hoop. Similarly, the longitudinal beam blanks may be considered to be blanks that are subsequently deformed to form the longitudinal beam portions of the roof hoop.

[0029] The roof rails and front and rear headers of a vehicle are structural members of the upper structural frame of the vehicle. In some examples, the rail portions included in the integrated roof hoop may be roof rail outer members of the vehicle frame, and the front and rear cross members included in the integrated roof hoop may be front and rear headers of the vehicle frame.

[0030] The integrated roof hoop may define the upper structural frame of the vehicle.

[0031] In some examples, deforming the bonded blank to form the integral roof ring of the vehicle frame includes hot stamping the bonded blank.Hot stamping is a process that allows ultra-high strength steel to be properly deformed to form the complex resulting structure of the integral roof ring.

[0032] In some examples, deforming the bonded blank can be accomplished in a single operation.Deforming the bonded blank in a single operation can improve the efficiency of the manufacturing process for the roof ring of a vehicle frame.

[0033] In another aspect, there is provided an integrated roof ring obtained by a method according to any of the examples described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Non-limiting examples of the present disclosure will now be described with reference to the accompanying drawings, in which:

[0035] Figure 1 An example of an integrated roof ring for a vehicle frame is shown;

[0036] Figure 2 shows an example of a plurality of blanks prior to being joined to form a joined blank;

[0037] Figure 3 shows an example of a schematic diagram of a joined blank formed from four linked blanks;

[0038] Figure 4 An example of a bonded blank including a patch blank is shown;

[0039] Figure 5 An example of a joined blank comprising five linked blanks is shown;

[0040] Figure 6 shows an example of an integrated roof ring after deforming the bonded blank;

[0041] Figure 7 shows an example of an enlarged view of a joining blank after deformation in an integral roof ring of a vehicle frame;

[0042] Figure 8 An example of a front view of an integrated roof ring of a vehicle frame is shown; and

[0043] Figure 9is a flow chart of a method for manufacturing an integral roof ring for a vehicle frame.

[0044] The drawings relate to example embodiments and may be used only to assist in understanding the claimed subject matter and not to limit the same in any sense. DETAILED DESCRIPTION

[0045] In these figures, the same reference numerals are used to identify matching elements.

[0046] Figure 1 An integrated roof hoop 100 of a vehicle frame according to an example of the present disclosure is schematically shown. The integrated roof hoop 100 comprises two longitudinal beam portions 10, 20, each of which is connected to a front cross beam 30 and a rear cross beam 40 to form a substantially closed ring.

[0047] In some examples, the integrated roof ring 100 can be mounted in an upper frame of a vehicle frame and can define an upper structural frame of the vehicle. The integrated roof ring can be connected to other parts of the vehicle frame, such as the A-pillar, C-pillar, and roof panel.

[0048] The integrated roof ring 100 can be made from multiple blanks in a single forming process. Figure 2 As schematically shown in FIG, the integrated roof ring 100 can be made of four blanks, namely a first blank 1, a second blank 2, a third blank 3, and a fourth blank 4, wherein the first blank 1 and the second blank 2 are longitudinal beam blanks 1, 2, and the third blank 3 and the fourth blank 4 are transverse beam blanks 3, 4. The third blank 3 is the front transverse beam blank 3, and the fourth blank 4 is the rear transverse beam blank 4. The blanks can be connected to form a combined blank. The longitudinal beam blanks 1, 2 can be connected to the front transverse beam blank 3 and the rear transverse beam blank 4. Therefore, as shown in FIG. Figure 3 A joined blank 5 comprising four blanks 1 , 2 , 3 , 4 is shown.

[0049] In a subsequent step, the bonded blank 5 is deformed. Specifically, it can be heated in a high-temperature furnace or alternative heating system to a temperature above the austenitization temperature, for example, approximately 900°C to 920°C. Subsequently, the bonded blank can be deformed and hardened in a stamping device. In particular, rapid cooling above the critical cooling rate of the bonded blank can achieve a martensitic microstructure and high ultimate tensile strength and yield strength.

[0050] In some examples, the blanks can be joined together by forming one or more overlapping regions 6, which are formed by partially overlapping the blanks. That is, one blank is only partially positioned on top of another blank, and then the blanks are joined together. As a result, the overlapping region has an increased thickness compared to the rest of the blank. This increased thickness can be used to tailor mechanical properties and provide localized reinforcement, such as in areas where increased strength and / or stiffness are desired.

[0051] In some examples, the overlap region 6 can be formed at or near the junction or transition between the front cross member 30 and one of the side member sections 10, 20. When different components are combined into the integrated roof ring 100 by deforming a single blank, these junctions have less material than they would if the components were manufactured separately and then welded together. By providing the overlap region 6 at or near these junctions, additional material can be added, thereby maintaining the mechanical behavior and kinematic properties of the roof ring 100. In other examples, the combined blank can be formed by edge-to-edge welding of the blanks (e.g., tailor-welding the blank), or the combined blank can be formed by using overlapping blanks in certain areas and edge-to-edge welding in other areas.

[0052] In some examples, the overlap region 6 can be formed substantially within the front cross member 30. That is, in these examples, the blanks forming the longitudinal beams overlap the blanks forming the front cross member 30. In the resulting product, the overlap can be completely or nearly completely located within the front cross member 30 of the resulting integrated roof hoop. In other examples, the overlap region 6 is formed at each of the junctions or transitions between the front and rear transverse beams 30, 40 and the two longitudinal beam sections 10, 20. The overlap can be accomplished by any of laser welding, arc welding, or spot welding.

[0053] In some examples, such as Figure 3 As shown, joining the blanks includes joining the first end of the first longitudinal beam blank 1 to the first end of the front transverse beam blank 3 and joining the second end of the first longitudinal beam blank 1 to the first end of the rear transverse beam blank 4, and joining the first end of the second longitudinal beam blank 2 to the second end of the front transverse beam blank 3 and joining the second end of the second longitudinal beam blank 2 to the second end of the rear transverse beam blank. The blanks can be welded to each other, for example, by laser welding or spot welding. Figure 3 The area 6 where the blanks are joined can be seen.

[0054] In some examples, joining the blanks to form the bonded blank 5 includes providing the bonded blank 5 having a substantially rectangular (ring-shaped) shape.

[0055] In some examples, the longitudinal beam blanks 1, 2 may be joined to the transverse beam blanks 3, 4 on the outside / upper side of the roof hoop. In other embodiments, the longitudinal beam blanks 1, 2 may be joined to the transverse beam blanks 3, 4 on the inside / lower side of the roof hoop.

[0056] In some examples, the overlap region 6 may have a length L1 corresponding to the width of the longitudinal member portions 10, 20 and may have a width W1 of at least 5 cm. In some examples, the overlap region 6 may be formed at each of the joints between the front and rear cross members 30, 40 and the two longitudinal member portions 10, 20. The appropriate size of the overlap region 6 is selected taking into account weldability, strength, and rigidity requirements. A larger overlap region 6 means increased thickness over a larger area, thereby locally increasing strength and rigidity in the roof hoop 100.

[0057] In other examples, the plurality of blanks may be formed from a plurality of blanks or sub-blanks, for example, of different thicknesses and / or different materials. In these examples, the plurality of blanks forming the longitudinal beam blank and / or the transverse beam blank may be tailor-welded blanks (TWBs). The TWBs may be formed by joining the sub-blanks using edge-to-edge welding, wherein the welding may include laser welding. In other examples, the plurality of blanks forming the longitudinal beam blanks 1, 2 and / or the transverse beam blanks 3, 4 may be joined by forming one or more overlapping regions 6, wherein the one or more overlapping regions 6 are formed by partially overlapping the blanks with respect to one another. In these cases, any of laser welding, arc welding, or spot welding may be used.

[0058] like Figure 4 As schematically shown in FIG, in some examples, a patch blank 7 can be joined to at least one of the multiple blanks that can form a combined blank 5. A patch blank can be considered herein to be a blank that completely overlaps another blank, i.e., the patch blank can be completely positioned within the perimeter of the other blank. The patch blank can be joined to the other blank by welding (e.g., spot welding or remote laser welding). The resulting combination of a "base" blank and a patch blank can sometimes be referred to as a "patch blank."

[0059] The patch blank 7 can be added substantially in the center portion of one of the blanks. The patch blank 7 can be added as a reinforcement to increase the strength of a specific area of the bonded blank 5. The patch blank 7 can be added in areas of the roof ring where additional strength may be needed (i.e., areas where high loads may be expected). In some examples, the patch blank 7 can be arranged within the front transverse beam blank 3 and / or the rear transverse beam blank 4. The patch blank 7 can be arranged substantially in the center portion of the front transverse beam blank 3 and / or the rear transverse beam blank 4. The patch blank 7 can also be arranged in the longitudinal beam blanks 1, 2, for example, in the area above the B-pillar of the vehicle. The patch blank 7 can be arranged substantially in the center portion of the longitudinal beam blanks 1, 2.

[0060] The patch blank 7 may be joined to the longitudinal beam blanks 1, 2 and / or transverse beam blanks 3, 4 by overlapping one of the blanks with the other and using spot welding. In other examples, alternative welding techniques may be used, such as laser welding or arc welding.

[0061] like Figure 5 As schematically shown in FIG, the integrated roof ring may include one or more additional cross members located between the front and rear cross members. In some examples, similar to Figure 5 For example, the integrated roof ring 100 can be made of a combined blank consisting of five blanks. Figure 2 and Figure 3 In addition to the blanks shown, the joining blank 5 may include a central transverse beam blank 8 located between the front transverse beam blank 3 and the rear transverse beam blank 4 and extending transversely from the longitudinal beam blank 1 to the longitudinal beam blank 2. The central transverse beam blank 8 can be joined to the longitudinal beam blanks 1, 2 by, for example, partially overlapping the blanks. The central cross member in the integrated roof hoop can provide enhanced crash performance and reduced weight for the upper structural frame of the vehicle.

[0062] exist Figure 5 In the example of FIG, the overlap region 6 formed by partially overlapping the front and rear transverse beam blanks 3, 4 with the longitudinal beam blanks 1, 2 may have a width W1 of at least 50% of the width of the front transverse beam blank 3 and the rear transverse beam blank 4. Figure 3 Compared to the example in Figure 1, a larger cross-section of longitudinal beam blanks 1 and 2 can overlap transverse beam blanks 3 and 4. In this case, the overlap region is not completely located within the longitudinal beam, but rather occupies a portion of the longitudinal beam as well as a portion of the rear cross member. By increasing the size of overlap region 6, increased stiffness can be provided over a wider area of the integrated roof ring, allowing it to withstand higher loads.

[0063] In this particular example, the patch blank 7 can be placed substantially in the center portion of the front transverse beam blank 3. In other examples, patch blanks 7 can also be added to the longitudinal beam blanks 1, 2 to further strengthen specific areas within those blanks. In some examples, the patch blank 7 can be placed substantially in the center portion of the longitudinal beam blanks 1, 2, overlapping a portion of the central transverse beam blank 8.

[0064] In some examples, the multiple blanks forming the bonded blank 5 can be made of different materials. In some examples, blanks 1, 2, 3, and 4 can be made of ultra-high strength steel (UHSS). Boron steel (e.g., 22MnB5) or other steel compositions mentioned above or mentioned above can be suitable UHSS. These blanks (e.g., boron steel blanks) can include an aluminum silicon coating or a zinc coating.

[0065] An example of 22MnB5 steel. The composition of MgO is summarized as follows by weight percentage (the rest is iron (Fe) and impurities):

[0066] Maximum carbon (C) content (%): 0.25

[0067] Maximum silicon (Si) content (%): 0.4

[0068] Maximum manganese (Mn) content (%): 1.4

[0069] Maximum phosphorus (P) content (%): 0.03

[0070] Maximum sulfur (S) content (%): 0.01

[0071] Aluminum (Al) content (%): 0.01 to 0.1

[0072] Maximum titanium (Ti) content (%): 0.05

[0073] Maximum niobium (Nb) content (%): 0.01

[0074] Maximum copper (Cu) content (%): 0.20

[0075] Maximum boron (B) content (%): 0.005

[0076] Maximum chromium (Cr) content (%): 0.35.

[0077] It may have, for example, a yield strength of 1100 MPa and an ultimate tensile strength of 1500 MPa.

[0078] It is another type of boron steel with higher strength. The yield strength can be 1400 MPa or higher, and the ultimate tensile strength can exceed 1800 MPa. The composition of MgO is summarized as follows by weight percentage (the rest is iron (Fe) and impurities):

[0079] Maximum carbon (C) content (%): 0.36

[0080] Maximum silicon (Si) content (%): 0.8

[0081] Maximum manganese (Mn) content (%): 0.8

[0082] Maximum phosphorus (P) content (%): 0.03

[0083] Maximum sulfur (S) content (%): 0.01

[0084] Aluminum (Al) content (%): 0.01 to 0.06

[0085] Maximum titanium (Ti) content (%): 0.07

[0086] Maximum niobium (Nb) content (%): 0.07

[0087] Maximum copper (Cu) content (%): 0.20

[0088] Maximum boron (B) content (%): 0.005

[0089] Maximum chromium (Cr) content (%): 0.50

[0090] Maximum molybdenum (Mb) content (%): 0.50.

[0091] The plurality of blanks forming the bonded blank 5 may comprise different materials and / or thicknesses. For example, (For example, and / or ) can be used in forming the blank of the bonding blank 5. The use of these types of materials in the hot forming and subsequent quenching process is due to the This results in a predominantly martensitic structure. One or more of the blanks may be made of different materials, e.g.

[0092] and and In comparison, it is another material used in hot stamping to increase elongation. The yield strength can be 800 MPa or higher, and the ultimate tensile strength can be 1000 MPa or higher. The composition of MgO is summarized as follows by weight percentage (the rest is iron (Fe) and impurities):

[0093] Maximum carbon (C) content (%): 0.10

[0094] Maximum silicon (Si) content (%): 0.6

[0095] Maximum manganese (Mn) content (%): 1.8

[0096] Maximum phosphorus (P) content (%): 0.03

[0097] Maximum sulfur (S) content (%): 0.01

[0098] Aluminum (Al) content (%): 0.01 to 0.1

[0099] Maximum titanium (Ti) content (%): 0.05

[0100] Maximum niobium (Nb) content (%): 0.10

[0101] Maximum copper (Cu) content (%): 0.20

[0102] Maximum boron (B) content (%): 0.005

[0103] Maximum chromium (Cr) content (%): 0.20.

[0104] In some examples, the integrated roof ring 100 can include regions having different ultimate tensile strengths according to any of the examples described herein. In some of these examples, different materials can be used in the bonded blanks.

[0105] In some of these examples, regions having different ultimate tensile strengths may have different microstructures.

[0106] Different microstructures can be produced in a hot-formed roof ring. These different microstructures can be produced by heating the bonded blank 5 above the austenitizing temperature and then controlling the cooling of the bonded blank 5 during forming to form the roof ring 100 for the vehicle frame. Cooling of different regions of the bonded blank 5 can be controlled by applying heaters to areas of the forming tool. Thus, the one-piece roof ring 100 includes regions having a predominantly martensitic structure and regions containing ferrite, pearlite, bainite, or a mixture thereof. Alternatively, different microstructures can be produced by partially heating (e.g., using a laser beam) a portion of the one-piece roof ring that has been press-hardened to change the predominantly martensitic structure to a structure containing ferrite and / or pearlite and / or bainite and / or tempered martensite, or a mixture thereof. The predominantly martensitic structure can have a tensile strength exceeding 1400 MPa, and in particular, exceeding 1500 MPa.

[0107] Therefore, the integrated roof hoop 100 can be made of a material that can effectively absorb energy during an impact.In some examples, the longitudinal beam blanks 1, 2 can be made of at least ultra-high strength steel.

[0108] The longitudinal beam portion 10, 20 may have a thickness of 0.5 to 2.5 mm, specifically 1 to 1.8 mm. The longitudinal beam portion 10 may have an ultimate tensile strength of 1000 to 2000 MPa, specifically 1500 to 2000 MPa. The longitudinal beam portion 10, 20 may be a roof rail outer portion of an upper structural frame of a vehicle.

[0109] In some examples, the longitudinal beam blanks 3 , 4 may be made of at least ultra-high strength steel.

[0110] The thickness of the cross beams 30 , 40 may be 0.5 to 2.5 mm, in particular 1 to 1.8 mm. The overlapping region may have a thickness of 2 to 5 mm, in particular 2 to 3.8 mm.

[0111] The front cross member 30 and the rear cross member 40 may have an ultimate tensile strength of 1000 to 2000 MPa, specifically 1500 to 2000 MPa.The front cross member 10 and the rear cross member 20 may be front and rear roof members of an upper structural frame of a vehicle.

[0112] In some examples, the thickness of the front and rear cross members 30, 40 may be less than the thickness of the longitudinal members 10, 20. In other examples, the thickness of the front and rear cross members 30, 40 may be equal to the thickness of the longitudinal members 10, 20.

[0113] In some examples, joining the blanks to one another includes welding the blanks to one another. In some examples, the blanks may be welded by spot welding and / or laser welding. In some examples, the joined blank formed by joining the blanks may be a tailor-welded blank. Joining the blanks before deformation can make joining easier because the blanks are substantially flat when joined. Welding the blanks by laser and / or spot welding before the deformation process can be efficient and precise.

[0114] Figure 6 An example of joined blanks after deformation is shown schematically. In this example, longitudinal beam blanks 1, 2 can be joined to transverse beam blanks 3, 4 by overlapping one of the blanks with the other and using spot welding before deformation. Figure 7 An enlarged view of the overlap region 6 of the junction of the front cross member 30 and the longitudinal beam portion 10 can be seen in FIG. In other examples, joining the blanks to each other may include forming one or more overlap regions 6 by partially overlapping the longitudinal beam blanks 1, 2 and the transverse beam blanks 3, 4 by laser or spot welding.

[0115] Joining the blanks creates welds or spot welds, critical areas that could easily break in a crash. Deformation after joining ensures that no welds or spot welds exist between the blanks, thereby providing a one-piece roof ring that is more crash-resistant than other upper structural frames 100 where the structural components are first formed and then joined. The hazards posed by these welds or spot welds are eliminated in the one-piece roof ring 100, thereby reducing the risk of cracks forming in the one-piece roof ring 100 in the event of a crash. Furthermore, the one-piece roof ring 100 can reduce the time required to build a vehicle and can reduce the thickness of adjacent components of the roof ring 100 without compromising the thickness of its structural elements.

[0116] In some examples, deforming the bonded blank 5 to form the integrated roof ring 100 may include thermoforming or hot stamping the bonded blank 5. Figure 8 A schematic front view of the thermoformed one-piece roof ring 100 can be seen in FIG.

[0117] In some examples, hot forming may include heating the bonded blank 5 to above the austenitizing temperature and then forming the bonded blank 5 to produce the integrated roof ring 100. In some examples, forming may include two or more forming steps. These forming steps may include, for example, forming, trimming, or cutting, and may be performed in a single multi-stage press. Examples of multi-stage presses are known, for example, from US Pat. No. 9,492,859 B2 and WO 2016142367 A1.

[0118] Deforming may include hot forming, i.e., heating the bonded blank 5 in an oven, possibly above the austenitizing temperature, specifically above Ac3. After heating in the oven, the bonded blank 5 is transferred to a press, where it is deformed to achieve the final shape of the integrated roof ring 100. Quenching may be performed during and immediately after forming. In particular, quenching may include cooling above a critical cooling rate to achieve a martensitic microstructure. In some examples, quenching may be avoided in selected portions of the roof ring.

[0119] In some examples, deformation is accomplished in a single operation.Deforming the bonded blank 5 may provide an integral roof ring 100 comprising two longitudinal beam portions 10, 20, each connected to a front cross beam 30 and a rear cross beam 40 to form a substantially closed ring.

[0120] In some examples, the roof hoop 100 having a substantially annular shape, including the front cross member 30 , the rear cross member 40 , the first longitudinal rail portion 10 , and the second longitudinal rail portion 20 , is manufactured by deforming a single blank.

[0121] The integrated roof ring 100 of the present disclosure may have improved impact resistance and may be produced with fewer steps, thereby improving crash performance while reducing the vehicle's structural frame mass and construction complexity.

[0122] Figure 9 A flow chart showing a method for manufacturing an integrated roof ring for a vehicle frame 200 is shown. The method includes providing a plurality of blanks 201 ; joining the blanks to each other to form a joined blank 202 ; and deforming the joined blank to form an integrated roof ring 203 .

[0123] In some examples, providing the plurality of blanks 201 may include providing two longitudinal beam blanks 1 and 2, a front transverse beam blank 3, and a rear transverse beam blank 4. In some examples, the plurality of blanks forming the combined blank 5 may be made of different materials. In some examples, the longitudinal beam blanks 1 and 2 and the front and rear transverse beam blanks 3 and 4 may be made of ultra-high strength steel.

[0124] In some examples, joining the blanks to form the bonded blank 202 may include forming one or more overlap regions 6 formed by partially overlapping the blanks. The overlap regions 6 may be formed in or near a junction or transition between the front cross member 30 and one of the side member portions 10, 20. The overlap regions may be formed in each of the junctions 6 between the front and rear cross members 30, 40 and both side member portions 10, 20.

[0125] Deforming the bonded blank to form the integral roof ring 203 may include hot forming or hot stamping the bonded blank 5. Different microstructures can be produced in the hot-formed roof ring. These different microstructures can be produced by heating the bonded blank 5 above the austenitizing temperature. In some examples, quenching may be performed during and after forming. Quenching may include cooling above a critical cooling rate to achieve a martensitic microstructure.

[0126] In some examples, different microstructures can be achieved by heating the bonded blank 5 above the austenitizing temperature and then controlling the cooling of the bonded blank 5 during forming the bonded blank 5 to form the integral roof ring 100. In some examples, quenching can be avoided in selected portions of the integral roof ring 100.

[0127] In some examples, deforming the bonded blank to form the integrated roof ring 203 can be accomplished in a single operation. The integrated roof ring 100 formed by deforming the bonded blank 203 includes two longitudinal beam portions, each of which is connected to a front cross beam and a rear cross beam to form a substantially closed ring.

[0128] For reasons of completeness, various aspects of this disclosure are set forth in the following numbered clauses:

[0129] Clause 1. A method for manufacturing an integral roof ring (100) for a vehicle frame, the method comprising:

[0130] Providing a plurality of blanks (1, 2, 3, 4);

[0131] joining the blanks to form a joined blank (5);

[0132] deforming the bonded blank (5) to form an integrated roof ring (100);

[0133] The integrated roof ring (100) comprises two longitudinal beam parts (10, 20), each longitudinal beam part being connected to a front cross beam (30) and a rear cross beam (40) to form a substantially closed ring.

[0134] Clause 2. The method for manufacturing an integrated roof ring (100) according to clause 1, wherein joining the blanks comprises forming one or more overlapping regions (6) formed by partially overlapping the blanks with each other.

[0135] Clause 3. The method for producing an integral roof ring (100) according to clause 2, wherein one of the overlapping regions (6) is formed in a junction of the front cross member (30) and one of the longitudinal beam sections (10, 20).

[0136] Clause 4. The method for manufacturing an integrated roof ring (100) according to clause 3, wherein the overlapping region (6) is formed substantially within the front cross member (30).

[0137] Clause 5. The method for producing an integrated roof ring (100) according to clause 4, wherein the overlapping region (6) has a length L1 corresponding to the width of the longitudinal member portion (10, 20) and has a width W1 of at least 5 cm.

[0138] Clause 6. The method according to any one of clauses 3 to 5, wherein an overlapping region (6) is formed in each of the joints of the front cross member (30) and the rear cross member (40) with the two longitudinal member parts (10, 20).

[0139] Clause 7. The method for manufacturing an integrated roof ring (100) according to any one of clauses 1 to 6, wherein joining the blanks comprises welding the blanks to each other.

[0140] Clause 8. The method for manufacturing an integrated roof ring (100) according to clause 7, wherein the welding comprises resistance spot welding and / or laser welding.

[0141] Clause 9. The method for manufacturing an integrated roof ring (100) according to any one of clauses 1 to 8, wherein deforming the bonded blank (5) to form the integrated roof ring (100) comprises hot stamping the bonded blank (5).

[0142] Clause 10. Method for producing a one-piece roof ring (100) according to any one of clauses 1 to 9, wherein the deformation is performed in one single operation.

[0143] Clause 11. A method for manufacturing an integrated roof ring (100) according to any one of clauses 1 to 10, wherein the two longitudinal beam portions (10, 20) comprise roof longitudinal beam outer portions, wherein the front cross beam (30) and the rear cross beam (40) comprise front and rear header beams of a vehicle frame.

[0144] Clause 12. Method for producing an integrated roof ring (100) according to any one of clauses 1 to 11, wherein the plurality of blanks (1, 2, 3, 4) comprises two longitudinal beam blanks (1, 2) and two transverse beam blanks (3, 4).

[0145] Clause 13. The method for manufacturing an integrated roof ring (100) according to clause 12, wherein the plurality of blanks (1, 2, 3, 4) further comprises a central beam blank (8).

[0146] Clause 14. A method for manufacturing an integrated roof ring (100) according to any one of clauses 1 to 13, wherein a patch blank (7) is joined to at least one blank of a plurality of blanks (1, 2, 3, 4) to form a joined blank (5).

[0147] Clause 15. The method for manufacturing an integrated roof ring (100) according to clause 14, wherein the patch blank (7) is arranged in the front transverse beam blank (3) and / or the rear transverse beam blank (4).

[0148] Clause 16. The method for manufacturing an integrated roof ring (100) according to clause 15, wherein the patch blank (7) is arranged substantially in a central portion of the front transverse beam blank (3) and / or the rear transverse beam blank (4).

[0149] Clause 17. The method for producing an integrated roof ring (100) according to any one of clauses 1 to 16, wherein the thickness of the cross member (30, 40) is less than the thickness of the longitudinal member portion (10, 20).

[0150] Clause 18. Method for producing an integrated roof ring (100) according to any one of clauses 1 to 17, wherein the thickness of the longitudinal beam portion (10, 20) and / or the thickness of the cross beam (30, 40) is 0.5 to 2.5 mm, in particular 1 to 1.8 mm.

[0151] Clause 19. Method for producing an integral roof ring (100) according to any one of clauses 1 to 18, wherein the plurality of blanks (1, 2, 3, 4) are made of ultra-high strength steel.

[0152] Clause 20. The method for producing an integrated roof ring (100) according to any one of clauses 1 to 19, wherein the integrated roof ring (100) has a tensile strength of 1500 to 2000 MPa.

[0153] Clause 21. An integral roof ring (100) obtainable by a method according to any one of clauses 1 to 20.

[0154] Clause 22. A roof ring (100) for a structural frame of a vehicle, the roof ring having a substantially annular shape and comprising:

[0155] Front cross member (30),

[0156] rear cross member (40),

[0157] a first longitudinal beam portion (10) and a second longitudinal beam portion (20),

[0158] Therein, a roof ring (100) is manufactured by deforming a single blank.

[0159] Clause 23. The integrated roof ring (100) of Clause 21, wherein the integrated roof ring (100) is part of an upper frame of a vehicle.

[0160] Clause 24. A vehicle comprising the integrated roof ring (100) according to clause 21 or 22.

[0161] Although only a few examples are disclosed herein, other substitutions, modifications, applications, and / or their equivalents are possible. In addition, all possible combinations of the described examples are contemplated. Therefore, the scope of this disclosure should not be limited by the specific examples, but should be determined solely by a reasonable reading of the appended claims.

Claims

1. A method for manufacturing an integral roof ring (100) for a vehicle frame, the method comprising: Providing a plurality of blanks (1, 2, 3, 4); joining the blanks to form a combined blank (5); deforming the combined blank (5) to form the integrated roof ring (100); The integrated roof ring (100) comprises two longitudinal beam parts (10, 20), each longitudinal beam part being connected to a front cross beam (30) and a rear cross beam (40) to form a substantially closed ring.

2. The method for manufacturing an integrated roof ring (100) according to claim 1, wherein: Joining the blanks includes forming one or more overlapping regions (6) formed by partially overlapping the blanks with each other.

3. The method for manufacturing an integrated roof ring (100) according to claim 2, wherein: One of the overlapping regions (6) is formed at a junction of the front cross member (30) and one of the longitudinal beam portions (10, 20).

4. The method for manufacturing an integrated roof ring (100) according to claim 3, wherein: The overlapping region (6) is substantially formed within the front cross member (30).

5. The method for manufacturing an integrated roof ring (100) according to claim 4, wherein: The overlapping region (6) has a length L1 corresponding to the width of the longitudinal beam portion (10, 20) and has a width W1 of at least 5 cm.

6. The method according to any one of claims 3 to 5, wherein An overlapping region (6) is formed in each of the joints of the front cross member (30) and the rear cross member (40) with the two longitudinal beam parts (10, 20).

7. The method for producing an integrated roof ring (100) according to any one of claims 1 to 6, wherein: Joining the blanks comprises welding the blanks to each other, and optionally comprises resistance spot welding and / or laser welding.

8. The method for producing an integrated roof ring (100) according to any one of claims 1 to 7, wherein: Deforming the bonded blank (5) to form the integrated roof ring (100) includes hot stamping the bonded blank (5).

9. The method for producing an integrated roof ring (100) according to any one of claims 1 to 8, wherein: The plurality of blanks (1, 2, 3, 4) include two longitudinal beam blanks (1, 2) and two transverse beam blanks (3, 4).

10. The method for producing an integrated roof ring (100) according to any one of claims 1 to 9, wherein: A patch blank (7) is joined to at least one of the plurality of blanks (1, 2, 3, 4) to form the combined blank (5), and optionally, wherein the patch blank (7) is arranged within the front transverse beam blank (3) and / or the rear transverse beam blank (4).

11. The method for manufacturing an integrated roof ring (100) according to claim 10, wherein: The patch blank (7) is arranged substantially in the central portion of the front transverse beam blank (3) and / or the rear transverse beam blank (4).

12. The method for producing an integrated roof ring (100) according to any one of claims 1 to 11, wherein: The thickness of the cross beam (30, 40) is smaller than the thickness of the longitudinal beam portion (10, 20).

13. The method for producing an integrated roof ring (100) according to any one of claims 1 to 12, wherein: The integrated roof ring (100) has a tensile strength of 1500 to 2000 MPa.

14. An integrated roof ring (100) obtainable by the method according to any one of claims 1 to 13.

15. A roof ring (100) for a vehicle structural frame, the roof ring (100) having a substantially annular shape and comprising: Front crossbeam (30), rear cross member (40), a first longitudinal beam portion (10) and a second longitudinal beam portion (20), The roof ring (100) is manufactured by deforming a single blank.

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