Window frames for vehicle doors, vehicle doors and methods of manufacture

Abstract

The present disclosure relates to methods for manufacturing unitary window frame of a front vehicle door, the unitary window frame being configured for being joined to an inner panel of the front vehicle door. The methods comprise providing a plurality of blanks, joining the blanks to form a combined blank and hot stamping the combined blank to form the unitary window frame. The unitary window frame comprises a substantially closed ring configured to surround a window of the front vehicle door, including an upper portion configured to be arranged above the window, a lower portion configured to be arranged below the window, and a rear portion configured to be arranged at a rear side of the window.

Description

AUTOTECH ENGINEERING S.L. DECEMBER 23, 2025 P2416 P5481PC00WINDOW FRAMES FOR VEHICLE DOORS, VEHICLE DOORS AND METHODS OF MANUFACTURE

[0001] The present application claims the benefit of EP24383452.0 filed on December 23rd, 2024. The present disclosure relates to vehicle doors and more particularly relates to window frames for vehicle doors, more particularly for front vehicle doors. The present disclosure further relates to methods for manufacturing such window frames.BACKGROUND

[0002] Vehicles such as cars incorporate a structural skeleton designed to withstand the loads that the vehicle may be subjected to during its lifetime. The structural skeleton is further designed to withstand and absorb impacts, in case of e.g. collisions with other cars or road structures.

[0003] The demand for weight reduction in the automotive industry has led to the development and implementation of lightweight materials or components, and related manufacturing processes and tools. The demand for weight reduction is especially driven by the goal of a reduction of CO2 emissions. The growing concern for occupant safety also leads to the adoption of materials which improve the integrity of the vehicle during a crash while also improving the energy absorption.

[0004] A process known as Hot Forming Die Quenching (HFDQ) typically uses boron steel sheets to create stamped components with Ultra High Strength Steel (UHSS) properties, with tensile strengths of e.g. 1.500 MPa or 2.000 MPa or even more. The increase in strength allows for a thinner gauge material to be used, which results in weight savings over conventionally cold stamped mild steel components, roll forming steel components or even tubular components. Throughout the present disclosure UHSS may be regarded as a steel having an ultimate tensile strength of 1.000 MPa or more after a press hardening process.

[0005] In a HFDQ process, a blank to be hot formed may be heated to a predetermined temperature e.g. austenization temperature or higher (and particularly between Ac3 and an evaporation temperature of e.g. a coating of the blank). A furnace system may be used for thispurpose. Depending on the specific needs, a furnace system may be complemented with additional heaters, e.g. induction heaters or infrared heaters. By heating the blank, the strength of the blank decreases, and deformability increases i.e. to facilitate the hot stamping process.

[0006] There are several known Ultra High Strength steels (UHSS) for hot stamping and hardening. The blank may be made e.g. of a boron steel, coated or uncoated, such as Usibor® 1500 (22MnB5) commercially available from ArcelorMittal. Other high strength materials such as 37MnB5 may also be used. UHSS may exhibit tensile strengths as high as 1.500 MPa, or even 2.000 MPa or more, particularly after a press hardening operation.

[0007] In addition to the Ultra High Strength Steels mentioned before, more ductile steels may be used in parts of the structural skeleton requiring energy absorption. Examples of ductile steels include Ductibor® 500, Ductibor® 1000 and CRL-340LA.

[0008] Hot Forming Die Quenching may also be called “press hardening” or “hot stamping”. These terms will be used interchangeably throughout the present disclosure.

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

[0010] The door structure of a car is an integral part of the vehicle structural system. A vehicle door structure may perform inter alia the following functions: the door provides structural resistance against intrusion from other vehicles or objects and may be configured to absorb energy and transfer loads in an appropriate manner to other areas of the vehicle and is generally designed to keep occupants safely inside the vehicle. At the same time, the door provides attaching surfaces for mechanisms, wiring, sensing devices, seals and interior trim. In addition, the door of course keeps the vehicle closed to the outside environment.

[0011] Structurally, vehicle doors such as car doors may comprise an inner panel (a panel arranged to face an “inside” of the vehicle), an outer panel (a panel facing the outside of the vehicle), and a “shield” in between the outer and inner panels. The shield may be regarded as formed by a plurality of reinforcements. These are generally denominated “shield”, since (like a shield) they protect the vehicle and its occupants.

[0012] The shield may comprise an inner shield, and an outer shield. The inner shield may be considered to comprise all elements between the inner panel and window glass. The outer shield may be considered to comprise all elements between the outer panel and the window glass. The inner shield may carry and guide the window glass, as well as electronic systems(e.g. motor for lowering and raising the window). The outer shield may include a Side Impact Protection Beam (SIPB).

[0013] Another structure which is part of the vehicle door is the window frame. Typically, window frames are made by cold forming, which leads to light window frames with relatively low tensile strength. Window frames may be attached to the inner panel of the vehicle or may be manufactured together with the inner panel i.e. as a unitary structure. Generally, crash performance of the window frame has been improved by using window frame reinforcements e.g. a tubular reinforcement placed in the waist beam of the window frame, press-hardened components joined to the frame or roll formed straight components.

[0014] Recently, the requirements and expectations from OEM’s and others for vehicles in terms of frontal impact crashworthiness have increased. As a specific example, the requirements of crashworthiness have become more demanding with respect to the Small Overlap Rigid Barrier test or “SORB” test.

[0015] It is an object of the present disclosure to provide door structures that are able to withstand increasingly high requirements in terms of crashworthiness without unduly increasing the overall weight of the structure.SUMMARY

[0016] In a first aspect, a method for manufacturing a unitary window frame of a front vehicle door is provided. The unitary window frame is configured for being joined to an inner panel of the front vehicle door. The method comprises providing a plurality of blanks and joining the blanks to form a combined blank. The method further comprises hot stamping the combined blank to form the unitary window frame, wherein the unitary window frame comprises a substantially closed ring configured to surround a window of the front vehicle door. The unitary window frame includes an upper portion configured to be arranged above the window, a lower portion configured to be arranged below the window and a rear portion configured to be arranged at a rear side of the window.

[0017] In accordance with this aspect, a window frame that is relatively light and resistant to frontal crash impacts is provided. Welding operations after forming are reduced, substantially reducing the heat affected zones of the resulting vehicle door. The window frame surrounds the window of the vehicle door and can reduce intrusion to inner parts of the vehicle in the case of frontal or side impact without a significant increase in weight. Safety for the occupants of the vehicle is therefore improved.

[0018] In some examples, joining the blanks may comprise forming one or more overlapping regions formed by partially overlapping the blanks with each other. Overlapping regions of the blanks provides regions with increased thickness. Local strength and / or stiffness in the unitary window frame in areas where high loads may be concentrated e.g. during a frontal collision may be achieved, particularly if the overlapping regions are relatively large (i.e. larger than needed purely for joining purposes).

[0019] In some examples, a first overlapping region may be formed at a junction of the upper portion with the lower portion of the unitary window frame. Greater thickness in the junction may increase stiffness and may enhance energy distribution to other parts of the window frame during a frontal impact or e.g. in a SORB test. The first overlapping region may be predominantly located within the lower portion. The first overlapping region may comprise a width Wi substantially corresponding to a width of a lower area of the upper portion. In some examples, the first overlapping region may have a height of at least 10 mm, specifically 10 -150 mm, more specifically 30 - 110 mm.

[0020] In some examples, a second overlapping region may be formed at a junction of the lower portion with the rear portion of the unitary window frame. The second overlapping region may be predominantly arranged in the rear portion. In further examples, a third overlapping region may be formed at a junction of the upper portion with the rear portion of the unitary window frame. The third overlapping region may be predominantly arranged in the upper portion of the unitary window frame.

[0021] In some examples, hot stamping the combined blank may comprise providing the lower portion of the unitary frame with a substantially U-shaped cross-section, the substantially U-shaped cross-section including a first sidewall, a second sidewall, and a bottom wall connecting the first sidewall with the second sidewall. The first sidewall has an upwardly extending first flange for joining to the inner panel, and the second sidewall has a downwardly extending second flange for joining to the inner panel, wherein the bottom wall of the U-shaped cross-section is configured for joining to the inner panel. The performance of the lower portion of the unitary window frame during a frontal impact may be increased.

[0022] In some examples, the combined blank may be formed by joining an upper blank, a lower blank and a rear blank, wherein the lower blank may comprise a central part, a front wing portion and a rear wing portion. The unitary window frame may comprise one or more of the overlapping regions formed by joining a wing portion of the lower blank to a lower area of the upper and / or rear blanks. A relatively light unitary window frame with enhanced crash performance may be provided.

[0023] In a further aspect, a unitary window frame as obtainable by a method according to any of the examples described herein is provided.

[0024] In yet a further aspect, a vehicle door comprising the unitary window frame according to the examples described herein which is joined to an inner panel is provided.

[0025] Ultimate tensile strength and yield strength mentioned throughout the present disclosure may be determined in standardized tensile strength tests as defined e.g. in ISO 6892-1, using e.g. A50 or A80 specimens in a quasi-static load test. A comparison between mechanical properties should be made using the same test conditions and specimen size. To compare yield strengths of different portions, specimens formed with the same materials as portions of the structural component may be prepared and tested in a Universal Testing Machine (UTM).

[0026] Throughout the present disclosure, it will be clear that the designation of steels 22MnB5, 34MnB4, 37MnB5 and others refer to the EN 10027 naming standard, in which the first number stands for the approximate amount of carbon content (weight percentage * 100), the letters refer to the most significant alloy components, and the trailing digit refers to the grade or variant.BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Non-limiting examples of the present disclosure will be described in the following, with reference to the appended figures, in which:Figure 1 schematically illustrates an inner panel of a prior art vehicle door;Figure 2A schematically illustrates an inner panel comprising a unitary window frame according to an example of the present disclosure;Figure 2B shows a unitary window frame before being joined to an inner panel;Figure 2C shows a cross-section of the inner panel shown in figure 2A cut through plane A-A; Figure 2D shows a vehicle comprising the inner panel 1 shown in figure 2A;Figure 2E schematically shows a plurality of blanks according to an example of the present disclosure;Figure 2F schematically shows a unitary window frame obtained after joining and hot stamping the blanks of figure 2E;Figure 3A shows a plurality of blanks prior to being joined to form a combined blank according to another example of the present disclosure;Figure 3B shows a combined blank formed by the blanks shown in figure 3A;Figure 3C shows a combined blank formed by the blanks shown in figure 3A according to yet another example of the present disclosure;Figure 3D shows a cross-section of the inner panel shown in figure 2A cut through plane A-A and comprising a unitary window frame obtained from the combined blank in figure 3C;Figure 4A shows a plurality of blanks according to another example of the present disclosure; Figure 4B shows a combined blank formed by the blanks shown in figure 4A;Figure 5A shows a plurality of blanks according to a further example of the present disclosure; Figure 5B shows a combined blank formed by the blanks shown in figure 5A;Figure 6 shows a combined blank according to yet another example of the present disclosure; andFigure 7 shows a flow chart of a method for manufacturing a unitary window frame of a vehicle door.

[0028] The figures refer to example implementations and are only be used as an aid for understanding the claimed subject matter, not for limiting it in any sense.DETAILED DESCRIPTION OF EXAMPLES

[0029] In these figures, the same reference signs have been used to designate matching elements.

[0030] Figure 1 shows an inner panel 1 of a front door of a vehicle of the state of the art. The inner panel may be a structural member of the vehicle door and is the panel that is facing the inside of the vehicle. The inner panel may be manufactured using a variety of techniques and materials.

[0031] The inner panel 1 comprises a bottom perimeter including a bottom edge 2, a front edge 3, a rear edge 4 and a lower portion of a window frame 5. The inner panel further includes an upper part surrounding the windows (not visible).

[0032] The inner panel 1 further comprises a window frame. 6 The window frame 6 is made of three independent components which are formed and subsequently welded together. Thewindow frame 6 is made by cold forming. It is also known to provide a window frame 6 made from one single cold formed component.

[0033] Figure 2A schematically represents an inner panel 1 of a door of a vehicle comprising a unitary window frame 100 according to an example of the present disclosure.

[0034] The unitary window frame 100 comprises an upper portion 110 configured to be arranged above the window, a lower portion 120 configured to be arranged below the window and a rear portion 130 configured to be arranged at a rear side of the window. The frame comprises a substantially closed ring configured to surround a window of the front vehicle door. In some examples, the unitary window frame may define a substantially triangular shape. The unitary window frame 100 is made by hot stamping. The unitary window frame 100 may have an ultimate tensile strength of at least 1 ,000 MPa.

[0035] The inner panel 1 may be part of a front door of a vehicle. The unitary window frame 100 may be joined to the inner panel 1 by welding e.g. resistance spot welding or laser welding. Further, the lower portion 120 of the window frame may be joined to the inner panel 1 with a plurality of weld lines.

[0036] Figure 2B shows the unitary window frame 100 before being joined to the inner panel 1. The figure schematically shows areas Ai, A2, A3 of the lower portion 120 of the unitary window frame 100 which may be welded to the inner panel 1 with a plurality of weld lines e.g. by resistance spot welding or laser welding. The plurality of weld lines may extend from a front end of the areas A1, A2, A3 of the lower portion 120 of the unitary window frame to a rear end.

[0037] In some examples, joining the unitary window frame 100 to the inner panel 1 may comprise welding an upper area A1, a lower area A2 and a central area A3 of the lower portion 120 of the unitary window frame to the inner panel 1. The central area A3 may be a longitudinally extending area arranged between the upper area A1 and the lower area A2 of the lower portion 120.

[0038] The unitary window frame 100 may be joined to the inner panel 1 with an upper weld line arranged substantially along an upper area A1 of the lower portion 120 of the window frame i.e. along a longitudinal area close to the upper end of the lower portion 120 of the window frame, and with a lower weld line arranged substantially along a lower area A2 of the lower portion 120 of the window frame i.e. along a longitudinal area close to the lower end of the lower portion 120 of the window frame.

[0039] Further, the unitary window frame 100 may be joined to the inner panel 1 with a middle weld line arranged substantially along a central area A3 of the lower portion 120 of the windowframe. It has been unexpectedly found that joining the lower part of the unitary window frame with an additional middle weld line may lead to an increase in the overall performance of the unitary window frame i.e. less intrusion may be achieved during a collision. In addition, as more welding areas may be provided, the welded surface of the lower area of the window frame is increased, substantially reducing the likelihood of welding failure during a crash event.

[0040] Figure 2C shows a cross-section of the inner panel shown in figure 2A cut through plane A-A.

[0041] Figure 2C shows that the lower portion 120 of the unitary window frame may have a substantially U-shaped or hat-shaped cross-section. A U-shaped lower portion 120 can provide bending strength and stiffness to the lower part of the unitary window frame 100. The lower portion 120 of the unitary window frame 100 may comprise a U-shaped cross-section substantially along the whole length of the lower portion 120. The performance of the lower portion of the unitary window frame during a frontal impact may be increased.

[0042] The substantially U-shaped cross-section may include a first sidewall 121, a second sidewall 122 and a bottom wall 123 connecting the first sidewall 121 with the second sidewall 122. Further, the first sidewall 121 may have an upwardly extending first flange 124 and the second sidewall 122 may have a downwardly extending second flange 125.

[0043] The upwardly extending first flange 124 and the downwardly extending second flange 125 may be configured for joining to the inner panel 1. Further, the bottom wall 123 of the U-shaped cross-section may also be configured for joining to the inner panel 1.

[0044] In some examples, joining the unitary window frame 100 to the inner panel 1 may comprise welding the upwardly extending first flange 124, the downwardly extending second flange 125 and the bottom wall 123 of the substantially U-shaped cross-section to the inner panel 1.

[0045] Figure 2C schematically shows an upper weld line, a lower weld line and a middle weld line joining the upwardly extending first flange 124, the downwardly extending second flange 125 and the bottom wall 123 of the substantially U-shaped cross-section to the inner panel 1. As shown, the upwardly extending first flange 121 may comprise an upper area Ai of the lower portion 120 of the unitary window frame 100, the bottom wall 123 may comprise a central area A3 and the downwardly extending second flange 122 comprises a lower area A20f the lower portion 120 of the unitary window frame 100.

[0046] In the specific example, the downward extending flange 125 extending from the second sidewall has a sinusoidal or wave-shaped portion.

[0047] In some examples, the lower portion 120 of the unitary window frame may have a thickness of 0.8 - 2.5 mm, specifically of 0.9 mm.

[0048] Figure 2D shows a vehicle comprising the inner panel 1 shown in figure 2A. As shown in the figure, the portions of the unitary window frame 100 are arranged such that, when the door of the vehicle is closed, the rear portion 130 of the unitary window frame is adjacent an upper part of the B-pillar 8 of the vehicle and the upper portion 110 of the unitary window frame is adjacent the A-pillar 7 of the vehicle. The lower portion 120 of the unitary window frame extends in a longitudinal direction of the vehicle from a front end 120a to a rear end 120b. The lower portion 120 may be a waist beam of the vehicle door.

[0049] The unitary window frame 100 is made from a plurality of blanks 10, 20, 30 joined together to form a combined blank 40. The unitary window frame 100 is obtained after hot stamping the combined blank 40. A window frame with increased resistance to frontal impact loads and comprising the waist beam of the vehicle door is obtained.

[0050] Figure 2E schematically shows a plurality of blanks 10, 20, 30 which may be joined and subsequently hot stamped to form the unitary window frame 100 shown in figures a 2A - 2D according to an example of the present disclosure.

[0051] Figure 2E shows an upper blank 10, a lower blank 20 and a rear blank 30. The lower blank 20 may comprise a central part 25 extending from a front end 20a to a rear end 20b. The lower blank 20 may further comprise one or more wing portions 21, 22 arranged at an upper end of the central part 25. The wing portions 21, 22 can be regarded as fingers or tabs which extend substantially in a longitudinal direction beyond the central part 25 of the lower blank 20.

[0052] In particular, the lower blank 20 may comprise a front wing portion 21 arranged extending substantially in a longitudinal direction from the front upper end of the central part 25 and a rear wing portion 22 arranged extending substantially in a longitudinal direction from the rear upper end of the central part 25. The front and rear wing portions 21, 22 extend in opposing directions. The lower blank 20 may further comprise a first recess 23 and a second recess 24 arranged below the wing portions 23, 24.

[0053] The upper blank 10 may extend from a front end 10a to a rear end 10b. The front end 10a of the upper blank may comprise a shape which may substantially match the shape of the front wing portion 21. Further, the rear blank 30 may extend from an upper end 30a to a lower end 30b, and the lower end 30b of the rear blank may comprise a shape substantially matching the shape of the rear wing portion 22. The upper blank 10 and rear blank 30 may be joined tothe lower blank 20 such that a first and second overlapping regions are formed in each one of the wing portions 21 , 22 of the lower blank 20.

[0054] A third overlapping region may be formed by joining the upper end 30a of the rear blank and the rear end 10b of the upper blank.

[0055] Figure 2F schematically shows the unitary window frame 100 obtained after joining and hot stamping the blanks 10, 20, 30 of figure 2E.

[0056] The total length L120 of the lower portion 120 of the window frame in this example is a sum of the length of the central part 25 and of the length of the wing portions 21, 22 of the lower blank 20.

[0057] As may be appreciated from figures 2E and 2F, the length L25 of the central part 25 of the lower blank 20 may be shorter than the length L120 of the lower portion 120 of the unitary window frame. A unitary window frame with enhanced crash performance may be obtained.

[0058] Figure 3A shows that a unitary window frame 100 may be manufactured by joining a plurality of blanks 10, 20, 30 to form a combined blank 40. Figure 3B shows a combined blank 40 formed by joining together the plurality of blanks of figure 3A.

[0059] The plurality of blanks may comprise an upper blank 10, a lower blank 20 and a rear blank 30. The combined blank 40 may be formed by joining the lower blank 20 to the upper and rear blanks 10, 30 and by joining the upper blank 10 to the rear blank 30. The blanks may be joined such that the rear blank 30 and the lower blank 20 are substantially perpendicular to one another. The combined blank 40 may form a substantially triangular shape.

[0060] Joining the blanks may comprise welding the blanks to each other. In some examples, the blanks may be joined to each other by laser welding. Joining the blanks before deformation may make the joining easier due to the blanks being substantially flat at the moment of joining. Welding blanks prior to the deformation process by laser and / or spot welding can thus be both efficient and precise.

[0061] In some examples, welding the blanks by laser welding may comprise forming Tailor Welded Blanks (TWB) by joining the blanks by edge-to-edge butt welding. In areas wherein the weight is to be minimized and no particular need for stiffness or strength is needed, overlapping blanks may be avoided.

[0062] In further examples, as shown in figure 3B, joining the blanks may comprise forming one or more overlapping regions 50, 60, 70 which are formed by partially overlapping the blanks with each other i.e. one blank may only be partially positioned over another blank andthe blanks are then joined to each other. An overlapping region thus acquires an increased thickness as compared to the remainder of the blanks. Such an increase in thickness provides local strength and / or stiffness in the unitary window frame in areas where high loads may be concentrated i.e. during a frontal collision.

[0063] Welding the blanks by laser welding may comprise partially overlapping the blanks with each other and forming a variety of weld seams along the perimeter of the overlapping region of the blanks. Arc welding or resistance spot welding may also be used to join overlapping blanks.

[0064] Figure 3B shows a combined blank comprising three overlapping regions 50, 60, 70. In this particular example, an overlapping region is formed in the combined blank 40 in each of the junctions between the upper, lower and rear blanks.

[0065] In some examples, the overlapping regions may comprise a thickness within the range of 1.4 - 3 mm, specifically 1.6- 2.5 mm. Areas of the window frame destined to receive higher loads e.g. frontal areas of the window frame or areas of the window frame which may receive linear loads after a frontal collision, may comprise overlaps with higher thicknesses e.g. thicknesses within the range of 2 mm - 3 mm.

[0066] The lower blank 20 may be joined to the upper and rear blanks 10, 30 forming an overlapping region 50, 60 in one or more of the junctions.

[0067] In the unitary window frame 100, a first overlapping region 50 may be formed at a junction of the upper portion 110 with the lower portion 120 of the unitary window frame. The junction area between the lower portion 120 and the upper portion 130 may be vulnerable during front impacts. Greater thickness in the junction may increase stiffness and may enhance energy distribution to other parts of the window frame, improving overall crash performance of the vehicle and the protection imparted by the safety cage.

[0068] As schematically shown in figure 3B, the first overlapping region 50 may be predominantly located within the lower portion 120 of the unitary window frame. In these examples, more than 50% of a surface area of the first overlapping region 50 may be located in the lower portion 120 of the unitary window frame, and less than 50 % may be located in the upper portion 110 of the unitary window frame, specifically more than 75% of the surface area of the first overlapping region 50 may be located in the lower portion 120 of the unitary window frame.

[0069] The first overlapping region 50 formed at the junction of the upper portion 110 with the lower portion 120 of the unitary window frame may comprise a width Wi substantiallycorresponding to a width of a lower area of the upper portion 110. In some examples, the first overlapping region 50 may have a height Hi of at least 10 mm, specifically 10- 150 mm, more specifically of 30 - 110 mm. In some examples, the area of the first overlapping region 50 may be of 10 - 220 cm2, specifically 30 - 100 cm2.

[0070] A second overlapping region 60 may be formed at a junction of the lower portion 120 with the rear portion 130 of the unitary window frame. The second overlapping region 60 formed at the junction of the lower portion 120 with the rear portion 130 of the unitary window frame may be predominantly arranged in the rear portion 130 of the unitary window frame. In these examples, more than 50% of a surface area of the second overlapping region 60 may be located in the rear portion 130 of the unitary window frame, and less than 50 % may be located in the lower portion 120 of the unitary window frame, specifically more than 75% of the surface area of the second overlapping region 60 may be located in the rear portion 130 of the unitary window frame.

[0071] In some examples, the second overlapping region 60 may have a width W2 substantially corresponding to a width of the rear portion 130. In some examples, the second overlapping region 60 may have a height H20f at least 10 mm, specifically of 10- 150 mm, more specifically of 30 - 110 mm. In some examples, the area of the second overlapping region 60 may be of 10 - 150 cm2, specifically 30 - 100cm2.

[0072] The rear blank 30 may be joined to the upper and lower blanks 10, 20 forming an overlapping region 60, 70 in one or more of the junctions.

[0073] A third overlapping region 70 may be formed at a junction of the upper portion 110 with the rear portion 130 of the unitary window frame. The third overlapping region 70 formed at the junction of the upper portion 110 with the rear portion 130 of the unitary window frame may be predominantly located in the upper portion 110 of the unitary window frame. In these examples, more than 50% of a surface area of the third overlapping region 70 may be located in the upper portion 110 of the unitary window frame, and less than 50 % may be located in the rear portion 130 of the unitary window frame, specifically more than 75% of the surface area of the third overlapping region 70 may be located in the upper portion 110 of the unitary window frame.

[0074] The third overlapping region 70 may have a height H3 substantially corresponding to a height of the upper portion 130 of the unitary window frame. In some examples, the third overlapping region 70 may have a width W3of at least 10 mm, specifically of 10 - 100 mm, more specifically of 30 - 80 mm. In some examples, the area of the third overlapping region 70 may be of 5 - 100cm2, specifically 20 - 70cm2.

[0075] In further examples, as schematically shown in figure 3C, a patch blank may be joined to one of the plurality of the blanks that form the combined blank. A patch blank may be regarded herein as a blank that entirely overlaps another blank, i.e. a patch blank may be positioned entirely within a perimeter of another blank. The patch blank may be joined to the other blank by welding, e.g. spot welding or remote laser welding. The resulting combination of “basic” blank and patch blank may sometimes be referred to as “patchwork blank”.

[0076] A patch blank may be added as a reinforcement in order to increase strength of a specific area of a blank. The overlapping region formed by overlapping a patch blank with another blank comprises increased thickness as compared to the remainder areas of the blank.

[0077] Figure 3C shows a further example of a combined blank 40 formed by joining together the plurality of blanks of figure 3A. In this example, the upper blank 10, the lower blank 20 and the rear blank 30 may be joined together by joining the blanks by edge-to-edge butt welding forming Tailor Welded Blanks.

[0078] Figure 3C shows a fourth overlapping region 80 formed by overlapping a patch blank and the lower blank 20 of the combined blank 40. The fourth overlapping region 80 may be formed by overlapping a patch blank with a lower portion of the lower blank 20. The lower portion 120 of the unitary window frame may be reinforced, and a unitary window frame with improved crash performance may be obtained.

[0079] The fourth overlapping region 80 may extend from a front end 120a of the lower portion 120 of the unitary window frame to a rear end 120b of the lower portion 120 of the unitary window frame. The patch blank may be predominantly located in a lower area of the lower portion 120 of the window frame. In some examples, the fourth overlapping region 80 may comprise about 50% of the surface area of the lower portion 120 of the unitary window frame.

[0080] In some examples, the fourth overlapping region 80 may have a height of H substantially corresponding to half of a height of the lower portion 120 and may have a width W4 substantially corresponding to a width of the lower portion 120.

[0081] Figure 3D schematically shows a cross-section of the inner panel panel 1 shown in figure 2A cut through plane A-A, wherein the inner panel 1 comprises a unitary window frame 100 obtained from the combined blank 40 of figure 3C.

[0082] As shown in the figure, the fourth overlapping region 80 may extend from the bottom wall 123 of the U-shaped cross-section of the lower portion 120 of the unitary window frame 100 to the downwardly extending second flange 125 of the U-shaped cross-section of the lower portion 120 of the unitary window frame 100.

[0083] Figure 3D schematically shows that the lower portion 120 of the unitary window frame comprises different thicknesses along its cross-section. E.g. the fourth overlapping region 80 including the second sidewall and the downwardly extending second flange of the U-shaped cross-section may comprise a thickness of 2 mm and the first sidewall and the upwardly extending first flange 124 of the U-shaped cross-section may comprise a thickness of 0.9 mm.

[0084] Figure 4A shows a plurality of blanks 10, 20, 30 which may be joined and hot stamped to form a unitary window frame 100 according to yet a further example of the present disclosure. Figure 4B shows a combined blank 40 formed by joining together the plurality of blanks of figure 4A.

[0085] In this example, the lower blank 20 may comprise a central part 25, a front wing portion 21 and a rear wing portion 22. A lower blank 20 comprising this configuration may lead to the obtention of a unitary window frame comprising a lower portion which is longer than the length of the central part 25 of the lower blank.

[0086] The use of a lower blank 20 with a central part 25 and wing portions 21 , 22 may provide a unitary window frame 100 with enhanced crash performance as compared to unitary window frames obtained from lower blanks lacking wing portions i.e. obtained from lower blanks which after forming lead to a unitary window frame with a lower portion which extends entirely from the front end of the upper portion to the rear end of the rear portion.

[0087] Figure 4B shows that the blanks in figure 2A may be joined forming one or more overlapping regions 50, 60, 70. One or more of the overlapping regions may be formed by joining a wing portion 21, 22 of the lower blank 20 to a lower area of the upper 10 and / or rear blanks 30.

[0088] The combined blank 40 may comprise a first overlapping region 50 formed by overlapping the front wing portion 21 of the lower blank and a lower area of the upper blank 10. In some examples, the first overlapping region 50 may comprise a width Wi substantially corresponding to a width of the lower area of the upper portion 10. The first overlapping region 50 may comprise a height Hi substantially corresponding to a height of the front wing portion 21 of the lower blank. In this example, the height of the first overlapping 50 region may be of 10 - 50 mm.

[0089] The combined blank 40 may comprise a second overlapping region 60 formed by overlapping the rear wing portion 22 of the lower blank 20 and the lower area of the rear blank 30. The second overlapping region 60 may comprise a height H2 substantially corresponding to a height of the rear wing portion 22 of the lower blank. The second overlapping region 60may comprise a width W2 substantially corresponding to a width of the lower area of the rear portion 30. In this example, the height H2 of the second overlapping 60 region may be of 10 -50 mm.

[0090] The combined blank 40 of the present example may further comprise a third overlapping region 70 formed by overlapping the upper and rear blanks 10, 30. The third overlapping region 70 in this example is quite similar to the third overlapping region 70 discussed with reference to figure 3B. In this example, the third overlapping region 70 may comprise a width W3 of 10 - 50 mm.

[0091] Figure 5A schematically shows yet a further example of a plurality of blanks 10, 20, 30 which may be joined and hot stamped to form a unitary window frame 100. The plurality of blanks 10, 20, 30 differ from the blanks shown in the example of figure 4A in the shape and size of the rear wing portion 22. The shape and size of the lower area of the upper blank 10 is also different from the one shown in the example of figure 4A.

[0092] Figure 5B shows a combined blank 40 formed by joining the plurality of blanks of figure 5A. The plurality of blanks are joined forming one or more overlapping regions which may be formed by joining a wing portion 21, 22 of the lower blank 20 to a lower area of the upper and / or rear blanks 10, 30.

[0093] The first overlapping region 50 of the present example is again formed by overlapping the front wing portion 21 and a lower area of the central part 25 of the lower blank 20 with a lower area of the upper blank 10. In this particular example, the first overlapping region is substantially L-shaped.

[0094] The first overlapping region 50 may comprise a first height Hn substantially corresponding to a height of the front wing portion 21 of the lower blank 20 e.g. height of 10 -50 mm, and a second height H12 substantially corresponding to a height of the lower blank 20 e.g. a height of 60 - 150 mm.

[0095] The combined blank 40 of the present example may comprise a second overlapping region 60 formed by overlapping the rear wing portion 22 of the lower blank 20 and the lower area of the rear blank 30. The second overlapping region 60 may comprise a height H2 substantially corresponding to a height of the rear wing portion 22 of the lower blank. In this particular example, the second overlapping region may comprise a height H2 of 50 - 150 mm.

[0096] The combined blank 40 of the example shown in figure 5B may further comprise a third overlapping region 70 formed by overlapping the upper and rear blanks 10, 30. The third overlapping region 70 may be very similar to the third overlapping region 70 discussed withreference to figure 3B. In this particular example, the third overlapping region 70 may comprise a width W3 of 50 - 100 mm.

[0097] Figure 6 schematically shows a combined blank 40 according to yet a further example of the present disclosure. The combined blank 40 is formed by joining an upper blank 10, a lower blank 20 and a rear blank 30, wherein the lower blank 20 comprises a central part 25, a front wing portion 21 and a rear wing portion 22.

[0098] In this example, the upper blank 10, the lower blank 20 and the rear blank 30 may be joined together by joining the blanks by edge-to-edge butt welding forming Tailor Welded Blanks.

[0099] Figure 6 shows a fourth overlapping region 80 formed by a patch blank and a lower portion of the lower blank 20 of the combined blank 40. The fourth overlapping region 80 may be very similar to the fourth overlapping region 80 discussed with reference to figures 3C and 3D. The lower portion 120 of the unitary window frame may be reinforced, and a unitary window frame with improved crash performance may be obtained.

[0100] In some examples (not illustrated), the plurality of blanks 10, 20, 30 forming the combined blank may be formed by a plurality of separate blanks. The plurality of blanks forming the upper, lower and rear blanks may be Tailor Welded Blanks. In other examples, the plurality of blanks forming the upper, lower and rear blanks may be joined by forming one or more overlapping regions formed by partially overlapping the blanks to each other.

[0101] In some examples, the plurality of blanks that form the combined blank 40 may be made from ultra-high strength steels (LIHSS). Boron steel, e.g. 22MnB5, or other steel compositions mentioned or referred to before may be suitable LIHSS. These blanks, e.g. boron steel blanks, may comprise an aluminum silicon coating or zinc coating.

[0102] llsibor® 1500P is an example of a 22MnB5 steel. The composition of llsibor® is summarized below in weight percentages (rest is iron (Fe) and impurities):Maximum carbon (C) (%): 0.25Maximum silicon (Si) (%): 0.4Maximum manganese (Mn) (%): 1.4Maximum phosphorus (P) (%): 0.03Maximum sulphur (S) (%): 0.01Aluminium (Al) (%): 0.01 - 0.1Maximum titanium (Ti) (%): 0.05Maximum niobium (Nb) (%): 0.01Maximum copper (Cu) (%): 0.20Maximum boron (B) (%): 0.005Maximum chromium (Cr) (%): 0.35

[0103] llsibor® 1500P may have a yield strength of e.g. 1.100 MPa, and an ultimate tensile strength of 1.500 MPa.

[0104] llsibor® 2000 is an example of a 37MnB5 steel, which is another boron steel with even higher strength. The yield strength of Usibor® 2000 may be 1.400 MPa or more, and the ultimate tensile strength may be above 1.800 MPa. The composition of Usibor® 2000 is summarized below in weight percentages (rest is iron (Fe) and impurities):Maximum carbon (C) (%): 0.36Maximum silicon (Si) (%): 0.8Maximum manganese (Mn) (%): 0.8Maximum phosphorus (P) (%): 0.03Maximum sulphur (S) (%): 0.01Aluminium (Al) (%): 0.01 - 0.06Maximum titanium (Ti) (%): 0.07Maximum niobium (Nb) (%): 0.07Maximum copper (Cu) (%): 0.20Maximum boron (B) (%): 0.005Maximum chromium (Cr) (%): 0.50Maximum molybdenum (Mb) (%): 0.50

[0105] MBW- K® 1900 is a manganese-boron steel 34MnB4 from ThyssenKrupp™ and suitable for hot stamping and the methods disclosed herein and which may have an ultimate tensile strength after stamping of 1900 MPa. The chemical composition of MBW-K® 1900 is summarised below in weight in percentages:Maximum carbon (C) (%): 0.38Maximum silicon (Si) (%): 0.40Maximum manganese (Mn) (%): 1.40Maximum phosphorus (P) (%): 0.025Maximum sulphur (S) (%): 0.010Minimum aluminium (Al) (%): 0.015Maximum chromium and molybdenum (Cr + Mo) (%): 0.50Maximum titanium (Ti) (%): 0.05Maximum boron (B) (%): 0.005

[0106] MBW® 1900 is another manganese-boron steel from ThyssenKrupp™ and it may have an ultimate tensile strength of 1.900 MPa after hot stamping. It is commercially available with aluminium-silicon coatings and suitable for hot stamping and the methods disclosed herein. The chemical composition of MBW® 1900 is summarized below in weight in percentages:Maximum carbon (C) (%): 0.38Maximum silicon (Si) (%): 0.40Maximum manganese (Mn) (%): 1.40Maximum phosphorous (P) (%): 0.025Maximum sulphur (S) (%): 0.010Minimum aluminium (Al) (%): 0.1Maximum niobium (Nb) (%): 0.05Maximum titanium (Ti) (%): 0.05Maximum chromium and molybdenum (Cr + Mo) (%): 0.50Maximum boron (B) (%): 0.005

[0107] B1800HS is a boron steel which may have an ultimate tensile strength of about 1.800 MPa and suitable for hot stamping and the methods disclosed herein. The chemical composition of B1800HS is summarized below in weight in percentages:Carbon (C) (%): 0.28 - 0.35Maximum silicon (Si) (%): 0.5Manganese (Mn) (%): 1.0 - 1.8Maximum phosphorous (P) (%): 0.025Maximum sulphur (S) (%): 0.010Aluminium (Al) (%): 0.01 - 0.06Maximum titanium (Ti) (%): 0.05Maximum boron (B) (%): 0.0050Maximum chromium and molybdenum and niobium (Cr + Mo + Nb) (%): 0.80

[0108] The plurality of blanks that form the composite blank may comprise different material and / or thicknesses. For example, blanks of press hardenable manganese boron steels like llsibor® or MBW-K® 1900 (e.g. llsibor® 1500 and / or llsibor® 2000) may be used in the blanks forming the composite blank. Using these types of materials in hot forming and subsequent quenching processes leads to a predominantly martensitic structure due to the Usibor®. One or more of the blanks may be made from a different material, e.g. Ductibor® 1000.

[0109] Ductibor® 1000 is another material used in hot stamping for increasing the elongation when compared to Usibor® 1500 and Usibor® 2000. The yield strength of Ductibor® 1000 may be 800 MPa or more, and the ultimate tensile strength of 1000 MPa or more. The composition of Ductibor® 1000 is summarized below in weight percentages (rest is iron (Fe) and impurities):Maximum carbon (C) (%): 0.10Maximum silicon (Si) (%): 0.6Maximum manganese (Mn) (%): 1.8Maximum phosphorus (P) (%): 0.03Maximum sulphur (S) (%): 0.01Aluminium (Al) (%): 0.01 - 0.1Maximum titanium (Ti) (%): 0.05Maximum niobium (Nb) (%): 0.10Maximum copper (Cu) (%): 0.20Maximum boron (B) (%): 0.005Maximum chromium (Cr) (%): 0.20

[0110] The obtained combined blank 40 is hot stamped and the unitary window frame 100 is formed. In particular, the combined blank 40 may be heated to above austenizationtemperature, e.g. around 900 - 920 °C in a furnace, and then formed to create the unitary window frame 100.

[0111] In some examples, forming may comprise two or more forming steps. These forming steps may comprise for example shaping, trimming or cutting and may be made in a single multi-stage press. Examples of multi-stage presses and methods are known from e.g. US 9,492,859 B2 and EP4219036.

[0112] Deforming may include hot forming i.e. heating the combined blank 40 in an oven, possibly above austenization temperature, specifically above Ac3. After heating in the oven, the combined blank 40 may be transferred to a press in which the combined blank 40 is deformed to obtain the final shape of the unitary window frame 100. During and immediately after forming, quenching may be carried out. In particular, the quenching may include cooling above a critical cooling rate so that a martensitic microstructure is obtained.

[0113] In some examples, hot stamping the combined blank 40 may comprise deforming the blank in one single operation.

[0114] Other processes suitable for the forming of the unitary frame include the processes described in pending application PCT / EP2024 / 072326 from the same applicant. The pending application describes a method for hot forming a structural component in a multi-step production line comprising: a press tool configured to draw blanks, wherein the press tool comprises an upper press die and a lower press die, a first post-press tool arranged downstream from the press tool and configured to perform a first post-press operation and, and comprising an upper first post-press die and a lower first post-press die, the upper press die and upper first post-press die being configured to operate in unison; and a transfer system to transfer blanks from the press tool to the first post-press tool, and the method comprises: providing a press hardenable boron steel blank, preferably with a content by weight of 0.32 -0.45% carbon, a manganese content of 0.6 - 1.5%, and a boron content of 0.003 - 0.006%, and wherein the boron steel blank optionally has an AlSi coating; heating the blank to above an austenization temperature; and drawing the heated blank in the press tool and transferring the formed blank from the press tool to the first post-press tool, wherein a temperature of the blank before drawing the blank is at least 600°C, specifically at least 650°C, and wherein a temperature of the formed blank before the first post-press operation is between 500° and 650 °C, and wherein a temperature of the formed blank at the end of the first post-press operation is between 400°C and 550°C. In preferred examples hereon, the press hardenable boron steel blank has a content by weight of 0.32 - 0.38%, a manganese content of 0.6 - 1.4% by weight and a boron content of 0.004 - 0.005% by weight. In further specific examples, the temperatureof the blank before drawing the blank is between 650°C and 900°C, specifically between 700°C and 800°C.

[0115] Figure 7 represents a flowchart of an example of a method 700 for manufacturing a unitary window frame of a vehicle door. The method 700 comprises, at step 702, providing a plurality of blanks, at step 704 joining the blanks to form a combined blank, and at step 706, hot stamping the combined blank to form the unitary window frame.

[0116] Embodiments hereof including different designs and processes have been described with reference to figures 2A - 6.

[0117] For reasons of completeness, various aspects of the present disclosure are set out in the following numbered clauses:Clause 1. A method 700 for manufacturing a unitary window frame 100 of a front vehicle door, the unitary window frame 100 being configured for being joined to an inner panel 1 of the front vehicle door, the method comprising:providing a plurality of blanks 10, 20, 30;joining the blanks to form a combined blank 40;hot stamping the combined blank 40 to form the unitary window frame 100, wherein the unitary window frame 100 comprises a substantially closed ring configured to surround a window of the front vehicle door, includingan upper portion 110 configured to be arranged above the window,a lower portion 120 configured to be arranged below the window, anda rear portion 130 configured to be arranged at a rear side of the window.Clause 2. The method 700 of clause 1, wherein joining the blanks comprises forming one or more overlapping regions 50, 60, 70, 80 formed by partially overlapping the blanks with each other.Clause 3. The method 700 of clause 2, wherein a first overlapping region 50 is formed at a junction of the upper portion 110 with the lower portion 120 of the unitary window frame.Clause 4. The method 700 of clause 3, wherein the firstoverlapping region 50 is predominantly located within the lower portion 120.Clause 5. The method 700 of clause 2 or 3, wherein the first overlapping region 50 comprises a width Wi substantially corresponding to a width of a lower area of the upper portion 110.Clause 6. The method 700 of any of clauses 3-5, the first overlapping region 50 further having a height Hi of at least 10 mm, specifically 10 - 150 mm, more specifically 30 - 110 mm.Clause 7. The method 700 of any of clauses 2 -6, wherein a second overlapping region 60 is formed at a junction of the lower portion 120 with the rear portion 130 of the unitary window frame.Clause 8. The method 700 of clause 7, wherein the second overlapping region 60 is predominantly arranged in the rear portion 130.Clause 9. The method 700 of clause 7 or 8, wherein the second overlapping region 60 has a width W2 substantially corresponding to a width of the rear portion 130.Clause 10. The method 700 of any of clauses 7 - 9, wherein the second overlapping region 60 has a height H2 of at least 10 mm, specifically of 10 - 150 mm, more specifically 30 - 110 mm.Clause 11. The method 700 of any of clauses 2 - 10, wherein a third overlapping region 70 is formed at a junction of the upper portion 110 with the rear portion 130 of the unitary window frame.Clause 12. The method 700 of clause 11, wherein the third overlapping region 70 is predominantly located in the upper portion 110 of the unitary window frame.Clause 13. The method 700 of clause 11 or 12, wherein the third overlapping region 70 has a height H3 substantially corresponding to a height of the upper portion 110.Clause 14. The method 700 of any of clauses 11 - 13, the third overlapping region 70 having a width W3of at least 10 mm, specifically of 10 - 100 mm, more specifically 30 - 80 mm.Clause 15. The method 700 of any of clauses 1 - 14, wherein joining the blanks 10, 20, 30 comprises welding the blanks to each other, and optionally comprises resistance spot welding and / or laser welding the blanks to each other.Clause 16. The method 700 of any of clauses 1 - 15, wherein all the blanks 10, 20, 30 of the plurality of blanks are made from an ultra high strength steel, and the unitary window frame has an ultimate tensile strength of at least 1 ,000 MPa after hot stamping.Clause 17. The method 700 of any of clauses 1 - 16, wherein hot stamping the combined blank 40 comprises providing the lower portion 120 of the unitary frame with a substantially II-shaped cross-section, the substantially U-shaped cross-section including a first sidewall 121, a second sidewall 122, and a bottom wall 123 connecting the first sidewall 121 with the second sidewall 122, and wherein the first sidewall 121 has an upwardly extending first flange 124 for joining to the inner panel 1, and the second sidewall 122 has a downwardly extending second flange 125 for joining to the inner panel 1, and wherein the bottom wall 123 of the U-shaped cross-section is configured for joining to the inner panel 1.Clause 18. The method 700 of clause 17, further comprising joining the unitary window frame 100 to the inner panel 1 of the front vehicle door, comprising:welding the upwardly extending first flange 125, the downwardly extending second flange 124, and the bottom wall 123 of the substantially U-shaped cross-section to the inner panel 1.Clause 19. The unitary window frame 100 as obtainable by any of the methods of clauses 1 -18.Clause 20. A vehicle door comprising the unitary window frame 100 of clause 19 joined to an inner panel 1.Clause 21. A vehicle comprising the vehicle door of clause 20.

[0118] Although only a number of examples have been disclosed herein, other alternatives, modifications, uses and / or equivalents thereof are possible. Furthermore, all possible combinations of the described examples are also covered. Thus, the scope of the present disclosure should not be limited by particular examples, but should be determined only by a fair reading of the claims that follow.

Claims

24CLAIMS1. A method for manufacturing a unitary window frame of a front vehicle door, the unitary window frame being configured for being joined to an inner panel of the front vehicle door, the method comprising:providing a plurality of blanks;joining the blanks to form a combined blank, wherein joining the blanks comprises forming one or more overlapping regions formed by partially overlapping the blanks with each other;hot stamping the combined blank to form the unitary window frame, wherein the unitary window frame comprises a substantially closed ring configured to surround a window of the front vehicle door, includingan upper portion configured to be arranged above the window,a lower portion configured to be arranged below the window, anda rear portion configured to be arranged at a rear side of the window.

2. The method of claim 1 , wherein a first overlapping region is formed at a junction of the upper portion with the lower portion of the unitary window frame.

3. The method of claim 2, wherein the first overlapping region is predominantly located within the lower portion.

4. The method of claim 2, the first overlapping region further having a height of at least 10 mm, specifically 10- 150 mm, more specifically 30 - 110 mm.

5. The method of any of claims 1 - 4, wherein a second overlapping region is formed at a junction of the lower portion with the rear portion of the unitary window frame.

6. The method of claim 5, wherein the second overlapping region is predominantly arranged in the rear portion.

7. The method of claim 5 or 6, wherein the second overlapping region has a width W2 substantially corresponding to a width of the rear portion 130, optionally wherein the second overlapping region has a height H2 of at least 10 mm, specifically of 10 - 150 mm, more specifically 30 - 110 mm.

8. The method of any of claims 1 - 7, wherein a third overlapping region is formed at a junction of the upper portion with the rear portion of the unitary window frame.

9. The method of any of claims 1 - 8, wherein joining the blanks comprises welding the blanks to each other, and optionally comprises resistance spot welding and / or laser welding the blanks to each other.

10. The method of any of claims 1 - 9, wherein all the blanks of the plurality of blanks are made from an ultra high strength steel, and the unitary window frame has an ultimate tensile strength of at least 1 ,000 MPa after hot stamping.

11. The method of any of claims 1 - 10, wherein hot stamping the combined blank comprises providing the lower portion of the unitary frame with a substantially U-shaped crosssection,the substantially U-shaped cross-section including a first sidewall, a second sidewall, and a bottom wall connecting the first sidewall with the second sidewall, andwherein the first sidewall has an upwardly extending first flange for joining to the inner panel, and the second sidewall has a downwardly extending second flange for joining to the inner panel, andwherein the bottom wall of the U-shaped cross-section is configured for joining to the inner panel.

12. The method of claim 11, further comprising joining the unitary window frame to the inner panel of the front vehicle door, comprising:welding the upwardly extending first flange, the downwardly extending second flange, and the bottom wall of the substantially U-shaped cross-section to the inner panel.

13. The unitary window frame as obtainable by any of the methods of claims 1 - 12.

14. A vehicle door comprising the unitary window frame of claim 13 joined to an inner panel.

15. A vehicle comprising the vehicle door of claim 14.

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