Roll forming system with heat treatment and related methods

Abstract

Disclosed herein are systems and methods for forming a final hollow body from a metal strip. The forming system can include a forming station, a joining station, an in-line heater, and a hydroforming station. Forming the final hollow body from the metal strip can include receiving the metal strip at the forming station and bending the metal strip into a desired cross-section at the forming station so that longitudinal edges of the metal strip abut. In some embodiments, the forming station includes at least one roller. The method can include welding the abutting longitudinal edges together as a seam region via the joining station to form an intermediate hollow body. The method can include heating the seam region of the intermediate hollow body with an in-line heater and hydroforming the intermediate hollow body into a final hollow body at the hydroforming station.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Provisional Application No. 63 / 199,202, filed December 14, 2020, the entirety of which is incorporated herein by reference.

[0002] FIELD OF THE DISCLOSURE This application relates to systems and methods for forming a final hollow body from a metal strip, and more particularly to roll forming systems and methods for forming a final hollow body from a metal strip. [Background technology]

[0003] Certain industries, including but not limited to the automotive industry, may utilize hollow or tubular metal structures for various applications. One method of forming such structures is by extruding a tubular structure and then hydroforming the tubular structure into the shape of the final tubular structure. An alternative method of forming such structures is by roll forming a metal sheet followed by seam welding to form a welded tubular structure and hydroforming the welded tubular structure into the final tubular structure. Traditionally, the integrity of the welds (or seams) in welded tubular structures has limited the ability of the welded tubular structures to be hydroformed. In particular, roll forming results in significant strain hardening of the material, which adversely affects the formability of the material. Furthermore, seam welding can result in a gradient in the strength / hardness profile across the weld, as strengthening based on grain refinement in the seam area, in addition to the formation of microcracks due to localized incipient melting. Therefore, the gradient in strength / hardness profile across the weld, as well as the reduced formability of the weld area, limits the ability to maintain weld integrity during the hydroforming process. Summary of the Invention

[0004] The terms "invention," "the invention," "this invention," and "the present invention" as used in this patent are intended to broadly refer to all of the subject matter of this patent and the claims that follow. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the claims that follow. The embodiments of the invention covered by this patent are defined by the claims that follow, not this Summary of the Invention. This Summary of the Invention is a high level overview of various embodiments of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used independently to determine the scope of the claimed subject matter. The subject matter should be understood by reference to the entire specification of this patent, any or all of the drawings, and appropriate portions of the claims.

[0005] According to certain embodiments, a forming system for forming a final hollow body from a metal strip includes a forming station, a bonding station, an in-line heater, and a hydroforming station. The forming station can receive the metal strip in a planar configuration and bend the metal strip into a desired cross-section such that the longitudinal edges of the metal strip are abutted. In some embodiments, the forming station includes at least one roller that can optionally bend the metal strip in a transverse direction. The bonding station can be downstream from the forming station and can weld the abutting longitudinal edges together as a seam region to form the intermediate hollow body. The in-line heater can be downstream from the bonding station and can selectively heat at least the seam region of the intermediate hollow body. The hydroforming station can be downstream from the in-line heater and can hydroform the intermediate hollow body into a final hollow body.

[0006] According to some embodiments, a method of forming a final hollow body from a metal strip includes roll forming the metal strip into a desired cross-section such that longitudinal edges of the metal strip abut, and welding the longitudinal edges together in a seam region to form an intermediate hollow body. The method can include heating at least the seam region of the intermediate hollow body, and hydroforming the intermediate hollow body into a final hollow body.

[0007] According to various embodiments, a roll forming system for forming an intermediate hollow body from a metal strip includes a forming station, a bonding station, an in-line heater, and a cooling station. The forming station may receive the metal strip in a planar configuration and may bend the metal strip into a desired cross-section such that longitudinal edges of the metal strip are abutted. In some embodiments, the forming station includes at least one roller. The bonding station may be downstream from the forming station and may weld the abutting longitudinal edges together as a seam region to form the intermediate hollow body. The in-line heater may be downstream from the bonding station and may selectively heat at least the seam region of the intermediate hollow body. The cooling station may be downstream from the in-line heater and may quench the intermediate hollow body.

[0008] The various embodiments described in this disclosure may include additional systems, methods, features, and advantages that may not necessarily be expressly disclosed herein, but will become apparent to one of ordinary skill in the art upon review of the following detailed description and the accompanying drawings. It is intended that all such systems, methods, features, and advantages be included within this disclosure and protected by the accompanying claims.

[0009] The features and components in the following figures are presented to emphasize the general principles of the present disclosure. Throughout the figures, corresponding features and components may be designated by matching reference characters for consistency and clarity. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a block diagram of components of a molding system, according to an embodiment. [Diagram 2] 1 illustrates a roll forming system of a forming system, according to an embodiment. [Diagram 3] 1 illustrates an intermediate hollow body before hydroforming and a final hollow body after hydroforming, according to an embodiment. [Figure 4] 1 illustrates an in-line heater for a roll forming system, according to an embodiment. [Diagram 5] 1 illustrates another in-line heater for a roll forming system, according to an embodiment. [Figure 6] 1 illustrates another in-line heater for a roll forming system, according to an embodiment. [Figure 7] 1 illustrates an intermediate hollow body formed from a roll forming system of a forming system, according to an embodiment. [Figure 8] 1 is a chart illustrating residual stresses in an intermediate hollow body, according to an embodiment. [Figure 9] 11 is a chart illustrating flaring displacement in an intermediate hollow body, according to an embodiment. [Figure 10] 1 is a chart illustrating yield stress and maximum tensile stress in an intermediate hollow body, according to an embodiment. [Figure 11] 1 is a chart illustrating average hardness in an intermediate hollow body, according to an embodiment. [Figure 12] 13 is a hardness heat map of an intermediate hollow body formed by a roll forming system without heat treatment, according to an embodiment. [Figure 13] 13 is a hardness heat map of an intermediate body formed by a roll forming system with heat treatment, according to an embodiment. [Figure 14] 1 is a chart illustrating yield strength and ultimate tensile strength over time for a final hollow body, according to an embodiment. [Figure 15]13 illustrates flaring in a hollow body molded without heat treatment, according to an embodiment. [Figure 16] 1 illustrates flaring in a hollow body formed by a roll forming system with heat treatment, according to an embodiment. [Figure 17] 1 is a chart illustrating flaring displacement in a hollow body, according to an embodiment. [Figure 18] 1 is a photograph of a microstructure of a hollow body according to an embodiment. [Figure 19] FIG. 2 is a block diagram of components of a molding system, according to an embodiment. [Figure 20] 1 is a chart illustrating the strength over time of a hollow body, according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Although the subject matter of the embodiments of the present invention has been described herein with specificity to meet statutory requirements, this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be construed as implying a particular order or arrangement among or between the various steps or elements, unless the order of the individual steps or arrangement of the elements is explicitly described. References to directions such as "top", "bottom", "upper", "bottom", "left", "right", "front", and "rear" are intended to refer to the orientations shown and described in the figure (or figures) to which the components and directions refer, among other things.

[0012] Any range disclosed herein should be understood to encompass all subranges contained therein. For example, a stated range "1 to 10" should be considered to include every subrange between the minimum value of "1" and the maximum value of "10" (and including the endpoints), i.e., every subrange beginning with a minimum value of 1 or more (e.g., 1 to 6.1) and ending with a maximum value of 10 or less (e.g., 5.5 to 10).

[0013] The aspects and features of the systems and methods described herein can be used with any suitable metal substrate and can be particularly useful with aluminum or aluminum alloys. In particular, desirable results can be obtained with alloys such as 1000 series, 2000 series, 3000 series, 4000 series, 5000 series, 6000 series, 7000 series, or 8000 series aluminum alloys. For an understanding of the numbering systems most commonly used to name and identify aluminum and its alloys, please refer to "International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys" or "Registration Record of Aluminum Association Alloy Designations and Chemical Compositions Limits for Aluminum Alloys in the Form of Castings and Ingot" (both published by The Aluminum Association).

[0014] Disclosed herein are forming systems and methods for forming a final hollow body from a metal strip. The forming system includes a roll forming system that forms the metal strip from a planar configuration into the shape of an intermediate hollow body, and a hydroforming system that forms the intermediate hollow body into the shape of the final hollow body. The roll forming system includes an in-line heater that heats at least the seam area of ​​the intermediate hollow body prior to the hydroforming process. The in-line heater may be any suitable device or combination of devices for heating at least the seam area. As some non-limiting examples, the in-line heater may include one or more of a rotating magnet, an induction in-line heater, a gas-powered in-line heater, an infrared in-line heater, an electric furnace, a combination thereof, or other suitable devices as needed. In some cases, the in-line heater may be a rapid in-line heater that rapidly heats the intermediate hollow body or a portion thereof. In certain aspects, heating at least the seam region of the intermediate hollow body may provide stress relief to the intermediate hollow body and / or allow for improved control of the material property distribution in the seam region (including but not limited to homogenizing the material properties throughout the seam region). In some embodiments, heating the intermediate hollow body may soften or reduce the hardness of at least the seam region of the intermediate hollow body prior to hydroforming. Conventional wisdom suggests that reducing the hardness (and therefore strength) of the seam region is undesirable because this softening will adversely affect the end-use strength of the material after hydroforming and therefore its crash performance. The inventors have discovered that this softening annealing temperature regime from this rapid post-weld annealing counterintuitively allows the material to better match the forces experienced during the hydroforming process, thereby allowing it to resist these forces without adversely affecting the end-use strength of the material. This rapid annealing is what makes this seat tube hydroforming application possible. In various aspects, the heat from the in-line heater can restore some ductility to the metal of the intermediate hollow body, improving the integrity of the welds during the hydroforming process.

[0015] 1 is a block diagram of a forming system 100 according to various embodiments, including a roll forming system 102 and a hydroforming system 104. The roll forming system 102 of the forming system 100 generally bends a metal strip from a flat or planar configuration into the form of an intermediate hollow body (e.g., a generally tubular form having any cross-sectional shape as desired). The hydroforming system 104 of the forming system 100 generally forms the intermediate hollow body into the shape of the final hollow body by forming the final hollow body onto the intermediate hollow body using a mold and high pressure fluid.

[0016] The roll forming system 102 includes a coil feed 106, one or more forming stations 108, a closing station 110, a bonding station 112, an in-line heater 114, and one or more cooling stations 116. Optionally, the roll forming system 102 can include other stations as desired. As a non-limiting example, a cutting station (not shown) can be provided downstream from the cooling station(s) 116 to cut the intermediate hollow body to a desired length.

[0017] A coil feed 106 of the roll forming system 102 feeds an elongated metal strip to the roll forming system 102. In various aspects, the elongated metal strip is provided in the form of a coil, although in other embodiments this need not be the case. From the coil feed 106, the metal strip is fed in a generally flat or planar configuration to forming station(s) 108, which sequentially bend the metal strip from the flat or planar configuration such that the longitudinal edges of the metal strip are joined. Depending on the desired cross-sectional shape of the intermediate hollow body, any desired number of forming stations 108 may be utilized, and the forming stations 108 may bend the metal strip as desired to obtain the desired cross-sectional shape. In certain embodiments, the forming stations 108 may include rollers that sequentially bend the metal strip from the flat or planar configuration, although various other suitable devices for bending the metal strip may be utilized at the forming stations 108.

[0018] A closing station 110 of the roll forming system 102 can further bend the bent metal strip from the forming station 108 such that the longitudinal edges of the bent metal strip are in abutting and / or overlapping relationship. In certain aspects, the closing station 110 includes fin pass rollers and / or other suitable devices for bringing the longitudinal edges into abutting and / or overlapping relationship. The joining station 112 joins the longitudinal edges together by a joining technique to form an intermediate hollow body having a seam area. In various embodiments, the joining station 112 includes a welding device, and the longitudinal edges are seam welded together to form the seam area.

[0019] The in-line heater 114 is downstream from the bonding station 112 and is configured to heat at least the seam region of the intermediate hollow body. The in-line heater 114 may be a variety of devices or combinations of devices suitable for heating at least the seam region, including, but not limited to, a rotating magnet, an induction in-line heater, a gas-powered in-line heater, an infrared in-line heater, an electric furnace, combinations thereof, or other suitable devices as desired.

[0020] In certain embodiments, the in-line heater 114 is controlled (e.g., by a controller (not shown) communicatively coupled to the in-line heater 114) such that the in-line heater 114 heats at least the seam area to a predetermined heating temperature for a predetermined heating time. In some cases, the predetermined heating time can be from greater than 0 seconds to less than 30 minutes, e.g., greater than 0 seconds to less than 20 minutes, greater than 0 seconds to less than 10 minutes, greater than 0 seconds to less than 5 minutes, greater than 0 seconds to less than 30 seconds, etc. In one non-limiting example, the predetermined heating time may be 30 seconds. In other embodiments, the predetermined heating time may be greater than 30 minutes and / or any other duration as desired. The "predetermined heating time" used includes both ramp-up time (e.g., the time it takes to reach a particular temperature) and dwell time (e.g., the time the metal product is held at a particular temperature). In some cases, the ramp-up time may be less than 10 seconds, while in other embodiments, the ramp-up time may be less than 10 seconds or greater than 10 seconds. In some cases, the predetermined time may include only the ramp-up time and may not include the dwell time. In various embodiments, the predetermined heating temperature may be 250° C. or higher, such as 300° C. to 575° C., 350° C. to 550° C., 375° C. to 500° C., 400° C. to 475° C., about 450° C., etc. In other embodiments, the predetermined heating time may be less than 250° C. and / or greater than 575° C., and / or the predetermined heating temperature may be any other temperature or temperature range as desired, optionally depending on the metal of the intermediate hollow body. In some non-limiting examples, the in-line heater 114 is controlled to heat the intermediate hollow body to a predetermined heating temperature of 375° C. to 525° C. for a predetermined heating time of 30 seconds. In certain embodiments, as described in more detail below with reference to Figures 7-13, heating the intermediate hollow body with an in-line heater 114 may allow for stress relaxation of the material, strength reduction, and control of material properties throughout the seam area, potentially improving seam integrity during the hydroforming process.

[0021] In some embodiments, the in-line heater 114 can be controlled to control at least one of the hardness gradient in the seam region, the residual stress in the seam region, the average hardness of the seam region, or the strength of the seam region. In other embodiments, the in-line heater 114 can be controlled to control other aspects of the seam region. As described in more detail below with reference to FIG. 8, in one non-limiting example, the in-line heater 114 can be controlled such that the residual stress in the seam region is less than about 20 MPa, such as less than about 15 MPa, although in other embodiments, the in-line heater 114 is controlled such that the residual stress is other suitable values ​​as desired. As described in more detail below with reference to FIG. 10, in one non-limiting example, the in-line heater 114 can be controlled such that the yield stress in the seam region is less than 300 MPa, e.g., less than 200 MPa, less than 150 MPa, etc., although in other embodiments, the in-line heater 114 is controlled such that the yield stress can be other suitable values ​​as desired. As will be described in more detail below with reference to FIG. 10, in one non-limiting example, the in-line heater 114 may be controlled such that the maximum tensile stress in the seam region is less than 300 MPa, e.g., less than 250 MPa, less than 2000 MPa, etc., although in other embodiments, the in-line heater 114 is controlled such that the maximum tensile stress can be other suitable values ​​as desired. As will be described below with further reference to FIGS. 11-13, the in-line heater 114 may be controlled such that the average hardness in the seam region is less than 100 Hv, such as less than 80 Hv, although in other embodiments, the in-line heater 114 is controlled such that the seam region has other average hardness values ​​as desired. In a further non-limiting example, as will be discussed below with further reference to FIGS. 12 and 13, the in-line heater 114 may be controlled such that the hardness gradient is reduced and the hardness distribution throughout the seam region is more uniform and homogenized, although in other embodiments, the in-line heater 114 is controlled to provide various hardness gradients as desired.In a non-limiting example, as described below with further reference to FIG. 14, the in-line heater 114 may be controlled such that the yield strength of the seam region is at least 290 MPa, although in other embodiments, the in-line heater 114 may be controlled such that the yield strength of the seam region is other values ​​as desired. One or more cooling stations 116 are downstream from the in-line heater 114 and are configured to quench the intermediate hollow body. The cooling station(s) 116 may be a variety of devices suitable for quenching the intermediate hollow body. In some non-limiting examples, the cooling station(s) 116 may be an air-cooled device, a water-cooled device, a combination thereof, or other suitable device as needed.

[0022] As previously described, the hydroforming system 104 of the molding system 100 shapes the intermediate hollow body into the shape of the final hollow body by forming the final hollow body onto the intermediate hollow body using a mold and high pressure fluid. Optionally, the molding system 100 can include a pre-bending station prior to the hydroforming system 104 to prepare the intermediate hollow body for the hydroforming process.

[0023] In various embodiments, the method of forming an intermediate hollow body includes providing a supply of metal strip at a coil feed 106. In some aspects, the supply of metal strip is provided in the form of a coil. In various embodiments, the metal strip may be various metals as desired, including but not limited to aluminum, aluminum alloys, steel, or other metals as desired. In one non-limiting example, the metal strip may be a 6000 series aluminum alloy.

[0024] The method includes feeding the metal strip from a coil feed 106 to forming station(s) 108. Feeding the metal strip from the coil feed 106 may include feeding the metal strip to the forming station(s) 108 in a generally flat or planar configuration. The method includes bending the metal strip from the flat or planar configuration with forming station(s) 108 to join longitudinal edges of the metal strip and bend the metal strip into the desired cross-sectional shape. In certain aspects, bending the metal strip with forming station(s) 108 includes sequentially bending the metal strip with a plurality of rollers to join longitudinal edges and bend the metal strip into the desired cross-sectional shape.

[0025] The method includes further bending the bent metal strip at a closing station 110 such that longitudinal edges of the bent metal strip are in abutting and / or overlapping relationship. In certain aspects, bending the bent metal strip at the closing station 110 includes bending the bent metal strip using fin pass rollers and / or other suitable devices for bringing the longitudinal edges into abutting and / or overlapping relationship. In various embodiments, the method includes joining the longitudinal edges together by a joining technique using a joining station 112 to form an intermediate hollow body having a seam region. In certain embodiments, joining the longitudinal edges includes seam welding the longitudinal edges with a welding device to form an intermediate hollow body having a seam region.

[0026] In various embodiments, the method includes heating at least the seam region of the intermediate hollow body with an in-line heater 114 and quenching the intermediate hollow body at cooling station(s) 116. In some embodiments, heating at least the seam region includes heating the intermediate hollow body with a rotating magnet, an induction in-line heater, a gas-powered in-line heater, an infrared in-line heater, an electric furnace, combinations thereof, or other suitable devices as desired. In certain embodiments, heating the intermediate hollow body with the in-line heater 114 includes heating the intermediate hollow body to a predetermined heating temperature for a predetermined heating time. In some cases, heating the intermediate hollow body to a predetermined heating temperature for a predetermined heating time includes heating the intermediate hollow body by the in-line heater 114 to a temperature of 250° C. or more and 550° C. or less for a duration of more than 0 seconds to less than or equal to 30 minutes. In some cases, heating the intermediate hollow body with the in-line heater 114 includes controlling at least one of a hardness gradient in the seam region, a residual stress in the seam region, an average hardness in the seam region, or a strength in the seam region.

[0027] In various embodiments, the method of forming the final hollow body includes hydroforming the intermediate hollow body using a hydroforming system 104 .

[0028] 2 illustrates a roll forming system 202 of the forming system. The roll forming system 202 may be substantially similar to the roll forming system 102 and includes a coil feed 206, which may be substantially similar to the coil feed 106, forming stations 208A-D, which may be substantially similar to the forming station(s) 108, a closing station 210, which may be substantially similar to the closing station 110, and a bonding station 212, which may be substantially similar to the bonding station 112. Like the roll forming system 102, the roll forming system 202 also includes an in-line heater 214, which may be substantially similar to the in-line heater 114, and a cooling station 216, which may be substantially similar to the cooling station(s) 116. As shown in FIG. 2, the metal strip 218 is fed from the coil feed 206 in a generally planar or flat configuration. Forming stations 208A-D sequentially bend metal strip 218 from a planar or flat configuration, represented in Figure 2 by raised longitudinal edges 220 of metal strip 218. After longitudinal edge 220 is joined, such as by welding, to an opposing longitudinal edge (not visible in Figure 2) via joining station 212, an intermediate hollow body 222 is formed, which may be heated by in-line heater 214 and quenched by cooling station 216.

[0029] FIG. 3 shows an intermediate hollow body 322, which may be substantially similar to the intermediate hollow body 222, and a final hollow body 324 after hydroforming by a hydroforming station, such as the hydroforming system 104.

[0030] 4-6 show non-limiting examples of devices that can be utilized as heaters in the roll forming systems of the forming systems. Various other types of heaters can be utilized in the roll forming systems described herein, as desired.

[0031] 4 shows a heater 414 that is a rotary magnet heater and includes a support 426 and one or more magnets 428 supported on the support 426. In certain embodiments, the heater 414 can receive an intermediate hollow body within an opening 429 of the heater 414, and the heater 414 may rotate about the intermediate hollow body to heat the intermediate hollow body, or the intermediate hollow body may rotate while the heater 414 is held stationary to heat the intermediate hollow body.

[0032] 5 shows heater 514, which is substantially similar to heater 414 and is a rotary magnet heater including a support 526 and one or more magnets 528. Compared to heater 414, the arrangement and number of magnets 528, as well as the shape of openings 529 in heater 514, are different. Like heater 414, heater 514 may rotate while the intermediate hollow body is held stationary, or vice versa.

[0033] FIG. 6 shows heater 614 being an induction heater having an induction coil 631 that can at least partially surround an intermediate hollow body 622 .

[0034] Figure 7 shows an example of a cut intermediate hollow body 722 being formed by a forming system, such as forming system 100. As shown in Figure 7, the intermediate hollow body 722 has a seam region 730 where the longitudinal edges of the metal strip are joined together by a joining station. Although the intermediate hollow body 722 is shown with a circular cross section, the intermediate hollow body 722 may have other shapes as desired depending on the forming station(s) included in the roll forming system.

[0035] As mentioned, a forming system with a roll forming system including an in-line heater can produce an intermediate hollow body with improved hydroforming performance. In some cases, heating with an in-line heater can reduce residual stress in the hoop direction at the seam area of ​​the intermediate hollow body compared to an intermediate hollow body without in-line heat treatment (FIG. 8). In various cases, heating with an in-line heater can improve the flaring displacement at the intermediate hollow body compared to an intermediate hollow body without in-line heat treatment (FIG. 9). In some cases, heating with an in-line heater can soften the intermediate hollow body compared to an intermediate hollow body without in-line heat treatment (FIG. 10). In various embodiments, heating with an in-line heater can reduce the hardness of the intermediate hollow body compared to an intermediate hollow body without in-line heat treatment (FIG. 11). In some embodiments, heating with an in-line heater can surprisingly improve the hardness distribution across the seam region of the intermediate hollow body compared to an intermediate hollow body without in-line heat treatment (FIGS. 11 and 12).

[0036] FIG. 8 shows the residual stresses in four samples of intermediate hollow bodies. Each intermediate hollow body was a 6000 series aluminum alloy and was formed by the same process except for heating in an in-line furnace as discussed below. Residual stresses were measured in the hoop (represented by arrow 732 in FIG. 7) direction of each intermediate product. The times / durations given in FIG. 8 are all dwell / soak times (i.e., the duration each body was held at a particular temperature) and each intermediate had a ramp-up time (i.e., the duration the body was heated to reach a particular temperature). For example, a duration shown as "0 seconds" means that the intermediate was heated during the ramp-up time but was not held at the temperature reached, not that the intermediate was not heated. The sample intermediate hollow body represented by bar 834 was formed without any heating from an in-line heater. The sample intermediate hollow body represented by bar 836 was formed with heating from an in-line heater to a temperature of 250° C. for a duration of 30 seconds. A sample intermediate hollow body represented by bar 838 was formed with heating from an in-line heater to a temperature of 300° C. for a duration of 30 seconds. A sample intermediate hollow body represented by bar 840 was formed with heating from an in-line heater to a temperature of 350° C. for a duration of 30 seconds. The residual stress represented by bar 834 was about 23 MPa, the residual stress represented by bar 836 was about 23 MPa, the residual stress represented by bar 838 was about 7 MPa, and the residual stress represented by bar 840 was about 15 MPa. As shown by comparing bar 834 to bars 836-840, respectively, the in-line heating reduced the residual stress in the seam region of the intermediate hollow body as the heating temperature increased. The reduction in residual stress imparted by the in-line heater can improve the formability and soundness of the seam region during hydroforming processing compared to intermediate hollow bodies without in-line heating.

[0037] FIG. 9 shows the flaring displacement in eight samples of intermediate bodies tested according to the Double Cone Flaring Test. The times / durations given in FIG. 9 are all dwell times / durations (i.e., the duration each body was held at a particular temperature) and each intermediate body had a ramp-up time (i.e., the duration the body was heated to reach a particular temperature). For example, a duration indicated as "0 seconds" means that the intermediate body was heated during the ramp-up time but was not held at the temperature reached, not that the intermediate body was not heated. Each intermediate hollow body was a 6000 series aluminum alloy and was formed by the same process except for heating in an in-line furnace as discussed below. The sample intermediate hollow body represented by bar 942 was formed without any heating from an in-line heater. The sample intermediate hollow body represented by bar 944 was formed with heating from an in-line heater to a temperature of 300° C. for a duration of 30 seconds. The sample intermediate hollow body represented by bar 946 was formed with heating from an in-line heater to a temperature of 300° C. for a duration of 20 minutes. A sample intermediate hollow body represented by bar 948 was formed by heating from an in-line heater at a temperature of 400° C. for a duration of 30 seconds. A sample intermediate hollow body represented by bar 950 was formed by heating from an in-line heater at a temperature of 400° C. for a duration of 0 seconds. A sample intermediate hollow body represented by bar 952 was formed by heating from an in-line heater at a temperature of 450° C. for a duration of 30 seconds. A sample intermediate hollow body represented by bar 954 was formed by heating from an in-line heater at a temperature of 450° C. for a duration of 0 seconds. A sample intermediate hollow body represented by bar 956 was formed by heating from an in-line heater at a temperature of 475° C. for a duration of 0 seconds. As shown by comparing bar 942 with the other bars 944-956, heating from an in-line heater at various combinations of temperature and duration increased the flaring displacement of the intermediate hollow body. In certain embodiments, varying the heating temperature had a more significant effect on the flaring displacement compared to varying the heating duration.For example, the difference between bars 944 and 948, where the duration was held constant but the heating temperature was changed, is compared to the difference between bars 944 and 946, where the heating temperature was held constant but the heating duration was changed.

[0038] FIG. 10 shows the yield stress and maximum tensile stress in five samples of intermediate hollow bodies. Each intermediate hollow body was a 6000 series aluminum alloy and was formed by the same process except for heating in an in-line furnace as discussed below. The times / durations given in FIG. 10 are all dwell times (i.e., the duration each body was held at a particular temperature) and each intermediate body had a ramp-up time (i.e., the duration the body was heated to reach a particular temperature). For example, a duration shown as "0 seconds" means that the intermediate body was heated during the ramp-up time but was not held at the temperature reached, not that the intermediate body was not heated. Sample intermediate hollow bodies represented by bars 1058 and 1068 were formed without any heating from an in-line heater. Sample intermediate hollow bodies represented by bars 1060 and 1070 were formed with heating from an in-line heater to a temperature of 300° C. for a duration of 20 minutes. Sample intermediate hollow bodies represented by bars 1062 and 1072 were formed with heating from an in-line heater to a temperature of 300° C. for a duration of 30 seconds. Sample intermediate hollow bodies represented by bars 1064 and 1074 were formed with heating from an in-line heater to a temperature of 400° C. for a duration of 30 seconds. Sample intermediate hollow bodies represented by bars 1066 and 1076 were formed with heating from an in-line heater to a temperature of 450° C. for a duration of 30 seconds. As shown in FIG. 10, heating from an in-line heater generally reduced the strength of the intermediate hollow bodies compared to the intermediate hollow bodies without in-line heating, and strength generally decreased as the heating temperature increased. The reduction in strength of the intermediate hollow bodies due to in-line heating can surprisingly improve formability and soundness during hydroforming processing compared to the intermediate hollow bodies without in-line heating.

[0039] FIG. 11 shows the average hardness of the seam area of ​​three samples of intermediate hollow bodies. The times / durations given in FIG. 11 are all dwell times (i.e., the duration each body was held at a particular temperature) and each intermediate body had a ramp-up time (i.e., the duration the body was heated to reach a particular temperature). For example, a duration indicated as "0 seconds" means that the intermediate body was heated during the ramp-up time but was not held at the temperature reached, not that the intermediate body was not heated. Each intermediate hollow body was a 6000 series aluminum alloy and was formed by the same process except for heating in an in-line furnace as discussed below. The sample intermediate hollow body represented by bar 1178 was formed without in-line heating. The sample represented by bar 1180 was formed with heating from an in-line heater to a temperature of 300° C. for a duration of 30 seconds. The sample represented by bar 1182 was formed with heating from an in-line heater to a temperature of 350° C. for a duration of 30 seconds. As shown by comparing bar 1178 to bars 1180 and 1182, heating from an in-line furnace reduced the average hardness of the seam region of the intermediate body compared to the average hardness of the seam region of the intermediate body without in-line heating. In certain aspects, the reduction in average hardness can surprisingly improve formability and soundness during the hydroforming process compared to an intermediate hollow body without in-line heating.

[0040] FIG. 12 is a hardness heat map of the seam region 1230 of an intermediate hollow body 1222, which is a 6000 series aluminum alloy and was formed without heating from an in-line furnace. In FIG. 12, the minimum hardness was 117 Hv, the maximum hardness was 149 Hv, and the average hardness was 129 Hv. FIG. 13 is a hardness map of the seam region 1330 of an intermediate hollow body 1322, which is the same 6000 series aluminum alloy as the intermediate hollow body 1222, but was formed with heating from an in-line furnace at a temperature of 350° C. and a dwell duration of 30 seconds. In FIG. 13, the minimum hardness was 55 Hv, the maximum hardness was 91 Hv, and the average hardness was 71 Hv. As shown by comparing FIG. 13 with FIG. 12, the hardness values ​​(minimum hardness, maximum hardness, and average hardness) of the seam region 1330 were all reduced compared to the corresponding hardness values ​​(minimum hardness, maximum hardness, and average hardness) of the seam region 1230. Furthermore, by comparing the heat distribution, the hardness of the seam region 1330 became more homogenous / had a more uniform hardness distribution throughout the seam region 1330 compared to the seam region 1230. The reduced hardness and more uniform hardness distribution imparted by heating with an in-line heater can surprisingly improve formability and soundness during the hydroforming process compared to an intermediate hollow body without in-line heating.

[0041] FIG. 14 shows the yield strength and ultimate tensile strength (i.e., strength after hydroforming) over the service life of five samples of final hollow bodies. Each final hollow body was a 6000 series aluminum alloy and was formed by the same process except as described below. All times / durations given in FIG. 14 are dwell times (i.e., duration that each body was held at a particular temperature) and each intermediate body had a ramp-up time (i.e., duration that the body was heated to reach a particular temperature). For example, a duration shown as "0 seconds" means that the intermediate body was heated during the ramp-up time but was not held at the temperature reached, not that the intermediate body was not heated. Sample final hollow bodies represented by bars 1484 and 1485 were formed without any heating from an in-line heater and hydroformed without post-form heat treatment or paint bake. Sample final hollow bodies represented by bars 1486 and 1487 were formed without heating from an in-line heater, but with post-forming heat treatment, and paint-back before hydroforming. Sample final hollow bodies represented by bars 1488 and 1489 were formed with heating from an in-line furnace at a temperature of 350° C. for a duration of 30 seconds, as well as with post-forming heat treatment and paint-back before hydroforming. Sample final hollow bodies represented by bars 1490 and 1491 were formed with heating from an in-line furnace at a temperature of 400° C. for a duration of 30 seconds, as well as with post-forming heat treatment and paint-back before hydroforming. Sample final hollow bodies represented by bars 1492 and 1493 were formed with heating from an in-line furnace at a temperature of 450° C. for a duration of 30 seconds, as well as with post-forming heat treatment and paint-back before hydroforming. In certain embodiments, depending on the particular application of the final hollow bodies, the final hollow bodies may need to meet certain strength requirements. As a non-limiting example, a particular automotive application may require a yield strength of at least 290 MPa. As shown in Figure 15, at a particular heating temperature, the final hollow bodies that were heated in-line had equal or greater in-service strength and / or were able to meet the required yield strength than those that were not heated in-line.In other words, the final hollow body that was heated in-line was more amenable to shaping by the hydroforming process, but still could provide equal or greater strength and / or meet performance requirements at a particular heating temperature.

[0042] FIG. 15 illustrates an intermediate hollow body 1522 formed without heat treatment, and FIG. 16 illustrates an intermediate hollow body 1622 formed by a forming system such as forming system 100. Both hollow bodies 1522, 1622 are the same 6000 series aluminum alloy, and both underwent the same double cone flaring test to produce the flared bodies 1522, 1622 shown in FIGS. 15 and 16. With reference to FIG. 15, the conventional intermediate hollow body 1522 achieved a flaring displacement of 17 mm before a crack 1523 formed on the intermediate body 1522, which formed in the weld or seam region 1530 of the hollow body 1522. With reference to FIG. 16, the hollow body 1622 was formed using the systems and methods described herein by heating the hollow body 1622 to a temperature of 400° C. during the ramp-up time, but not holding at the temperature reached. The hollow body 1622 achieved a flaring displacement of approximately 54 mm before a crack 1623 formed on the intermediate body 1622, the crack 1623 formed in the base metal of the intermediate body 1622 (i.e., in a portion of the intermediate body 1622 other than the weld or seam region 1630), and the weld or seam region 1630 was not cracked. By comparing FIG. 15 to FIG. 16, the intermediate hollow body 1622 had improved formability and integrity compared to the hollow body 1522 without in-line heating, as represented by the improved flaring performance (54 mm vs. 17 mm). Furthermore, the location of the crack 1623 within the hollow body 1622 (i.e., in the base metal rather than the seam region 1630) represents a more homogenous microstructure and / or homogenous hardness distribution compared to that of the intermediate body 1522.

[0043] FIG. 17 shows the flaring displacement in five samples of intermediates formed according to the methods described herein and a control sample (represented by bar 1711) that was formed without heating. All samples were tested according to the Double Cone Flaring Test. Each sample was a 6000 series aluminum alloy and was formed by the forming system. All samples, except the control sample, included heating as part of the forming process, and for these samples, the duration each sample was heated was the same, but the temperature each sample was heated to was different. In particular, the sample intermediate represented by bar 1701 was formed by heating the sample with an in-line heater to a temperature of 380° C., the sample intermediate represented by bar 1703 was formed by heating the sample with an in-line heater to a temperature of 400° C., the sample intermediate represented by bar 1705 was formed by heating the sample with an in-line heater to a temperature of 425° C., the sample intermediate represented by bar 1707 was formed by heating the sample with an in-line heater to a temperature of 450° C., and the sample intermediate represented by bar 1709 was formed by heating the sample with an in-line heater to a temperature of 525° C. As before, the sample formed without heating is represented by bar 1711.

[0044] As shown in FIG. 17, the sample represented by bar 1701 had an average flaring displacement of 42.9 mm, the sample represented by bar 1703 had an average flaring displacement of 40.7 mm, the sample represented by bar 1705 had an average flaring displacement of 37.4 mm, the sample represented by bar 1707 had an average flaring displacement of 41.5 mm, and the sample represented by bar 1709 had an average flaring displacement of 43.9 mm. The control sample represented by bar 1711 had an average flaring displacement of 17 mm. As shown, each sample formed by heating (e.g., bars 1701, 1703, 1705, 1707, and 1709) exhibited a flaring displacement greater than that of the control sample (bar 1711), and in particular, exhibited a flaring displacement that was at least twice that of the control sample. The results in FIG. 17 indicate that the formability of the body was improved when formed by heating.

[0045] 18 is a photograph of the microstructure of a seam region 1830 in a hollow body 1822 formed according to methods described herein. The hollow body 1822 is a 6000 series aluminum alloy that was formed by heating the sample with an in-line heater to a temperature of 400° C. during a ramp-up period, but not holding at that temperature once reached. As shown in FIG. 18, the microstructure of the seam region 1830 is restored to a nearly equiaxed, fully recrystallized microstructure compared to the non-seamed regions of the hollow body 1622, thereby producing an improved hollow body heating according to embodiments of the present disclosure.

[0046] 19 is a block diagram of another molding system 1900, according to an embodiment. The molding system 1900 is substantially similar to the molding system 100, and includes a roll forming system 102 and a hydroforming system 104. Compared to the molding system 100, the molding system 1900 further includes a paint baking system 1905. The paint baking system 1905 may be various suitable systems, devices, and mechanisms for performing a paint baking cycle on the hollow body formed by the roll forming system 102 and the hydroforming system 104. In certain embodiments, performing a paint baking cycle on the hollow body formed by the roll forming system 102 and the hydroforming system 104 can improve the strength of the hollow body during its life, compared to both a conventional formed hollow body without a paint baking cycle and a hollow body formed by the roll forming system 102 and the hydroforming system 104 but without a paint baking cycle. In some embodiments, the paint bake cycle can improve strength during service to more closely match the peak yield strength of the alloy from which the hollow body is formed, as compared to a hollow body formed without a paint bake cycle.

[0047] FIG. 20 is a chart showing the in-service performance of ten samples of intermediates formed according to the methods described herein. The units on the y-axis of the chart in FIG. 20 are Mpa. Each sample was a 6000 series aluminum alloy and was formed by heating during roll forming. The duration each sample was heated was the same, but the temperature each sample was heated to varied as discussed below. Additionally, some samples were subjected to a paint bake cycle which was performed identically for each of those samples. Sample intermediate represented by bar 2001A was formed by heating the sample with an in-line heater to a temperature of 380° C. Sample intermediate represented by bar 2001B was formed by heating the sample with an in-line heater to a temperature of 380° C., and compared to the sample represented by bar 2001A, the sample represented by bar 2001B was further subjected to a paint bake cycle. Sample intermediate represented by bar 2003A was formed by heating the sample with an in-line heater to a temperature of 400° C. The sample intermediate represented by bar 2003B was formed by heating the sample with an in-line heater to a temperature of 400° C., and in comparison to the sample represented by bar 2003A, the sample represented by bar 2003B was further subjected to a paint bake cycle. The sample intermediate represented by bar 2005A was formed by heating the sample with an in-line heater to a temperature of 425° C. The sample intermediate represented by bar 2005B was formed by heating the sample with an in-line heater to a temperature of 380° C., and in comparison to the sample represented by bar 2005A, the sample represented by bar 2005B was further subjected to a paint bake cycle. The sample intermediate represented by bar 2007A was formed by heating the sample with an in-line heater to a temperature of 450° C. The sample intermediate represented by bar 2007B was formed by heating the sample with an in-line heater to a temperature of 450° C., and compared to the sample represented by bar 2007A, the sample represented by bar 2007B further underwent a paint bake cycle.Sample intermediate represented by bar 2009A was formed by heating the sample with an in-line heater to a temperature of 525° C. Sample intermediate represented by bar 2009B was formed by heating the sample with an in-line heater to a temperature of 525° C., and in comparison to the sample represented by bar 2009A, the sample represented by bar 2009B further underwent a paint bake cycle. As shown by comparing the samples that had a paint bake cycle (e.g., samples represented by bars 2001B, 2003B, 2005B, 2007B, and 2009B) to the corresponding samples that did not (e.g., samples represented by bars 2001A, 2003A, 2005A, 2007A, and 2009A), the samples that had a paint bake cycle exhibited significantly improved strength performance during service. As non-limiting examples, all paint bake cycle samples exhibited in-service strength performance of at least 200 Mpa, and samples heated to a temperature of at least 400° C. during roll forming exhibited in-service strength performance of greater than 250 Mpa, such as about 300 Mpa. The results in FIG. 20 also show that, in general, increased heating temperatures during roll forming in combination with paint bake cycles can produce hollow bodies with the best strength performance. It is noted that while the samples with paint bake cycles improved in-service strength performance, the samples without paint bake cycles generally exhibited improvement over conventionally molded hollow bodies, and their in-service strength may be suitable for various product applications (e.g., meeting minimum yield strength requirements).

[0048] Provided below is a collection of exemplary embodiments, including at least some explicitly listed as "exemplary," that provide further illustration of various exemplary types according to the concepts described herein. These embodiments are not meant to be mutually exclusive, exhaustive, or limiting, and the present invention is not limited to these exemplary embodiments, but rather encompasses all possible modifications and variations within the scope of the issued claims and their equivalents.

[0049] Example 1. A forming system for forming a final hollow body from a metal strip, comprising: a forming station configured to receive the metal strip in a planar configuration, bend the metal strip into a desired cross-section so that longitudinal edges of the metal strip abut, the forming station including at least one roller; a joining station downstream from the forming station configured to weld the abutting longitudinal edges together as a seam area to form an intermediate hollow body; an in-line heater downstream from the joining station configured to selectively heat at least the seam area of ​​the intermediate hollow body; and a hydroforming station downstream from the in-line heater configured to hydroform the intermediate hollow body into the final hollow body.

[0050] Example 2. A forming system as described in any preceding or following example or combination of examples, wherein the forming station includes a plurality of rollers, and the forming station is configured to sequentially bend the metal strip from the planar configuration.

[0051] Example 3. The molding system of any preceding or following example or combination of examples, wherein the in-line heater includes at least one of a rotating magnet, an induction in-line heater, a gas-powered in-line heater, an infrared in-line heater, or an electric furnace.

[0052] Example 4. A molding system as described in any preceding or subsequent example or combination of examples, wherein the in-line heater includes the rotating magnet and the intermediate hollow body is movable along an axis parallel to the axis of rotation of the rotating magnet.

[0053] Example 5. The forming system of any preceding or subsequent example or combination of examples, further comprising a quenching station between the joining station and the hydroforming station, the quenching station configured to selectively quench the intermediate hollow body.

[0054] Example 6. A molding system as described in any preceding or subsequent example or combination of examples, further including a controller communicatively coupled to the in-line heater, the controller configured to control the in-line heater such that the in-line heater heats the intermediate hollow body for a duration of greater than 0 seconds to less than or equal to 30 seconds.

[0055] Example 7. The molding system of any preceding or subsequent example or combination of examples, further comprising a controller communicatively coupled to the in-line heater, the controller configured to control the in-line heater such that the in-line heater heats the intermediate hollow body at a temperature between 300°C and 550°C.

[0056] Example 8. A method for forming a final hollow body from a metal strip, comprising: roll-forming the metal strip into a desired cross-section so that the longitudinal edges of the metal strip are abutted; welding the longitudinal edges together into a seam region to form an intermediate hollow body; heating at least the seam region of the intermediate hollow body; and hydroforming the intermediate hollow body into the final hollow body.

[0057] Example 9. The method of any preceding or following example or combination of examples, wherein the metal strip comprises a 6000 series aluminum alloy.

[0058] Example 10. The method of any preceding or following example or combination of examples, further comprising quenching the intermediate hollow body prior to hydroforming the intermediate hollow body into the final hollow body.

[0059] Example 11. The method of any preceding or following example or combination of examples, wherein the heating includes heating a non-seamed area portion of the intermediate hollow body.

[0060] Example 12. The method of any preceding or following example, or combination of examples, wherein heating at least the seam area includes heating at least the seam area at a temperature of from 300°C to 550°C for a duration of from greater than 0 seconds to less than or equal to 30 seconds.

[0061] Example 13. The method of any preceding or following example or combination of examples, wherein heating at least the seam area includes heating with at least one of a rotating magnet, an induction in-line heater, a gas-powered in-line heater, an infrared in-line heater, or an electric furnace.

[0062] Example 14. The method of any preceding or subsequent example or combination of examples, further comprising controlling at least one of a hardness gradient in the seam region or a strength in the seam region prior to hydroforming by controlling at least one of a duration of the heating of the seam region or a temperature of the heating of the seam region.

[0063] Example 15. A roll-forming system for forming an intermediate hollow body from a metal strip, comprising: a forming station configured to receive the metal strip in a planar configuration and bend the metal strip into a desired cross-section so that longitudinal edges of the metal strip abut, the forming station including at least one roller; a joining station downstream from the forming station and configured to weld the abutting longitudinal edges together as a seam region to form the intermediate hollow body; an in-line heater downstream from the joining station and configured to selectively heat at least the seam region of the intermediate hollow body; and a cooling station downstream from the in-line heater and configured to quench the intermediate hollow body.

[0064] Example 16. The roll forming system of any preceding or following example or combination of examples, wherein the in-line heater includes at least one of a rotating magnet, an induction in-line heater, a gas-powered in-line heater, an infrared in-line heater, or an electric furnace.

[0065] Example 17. The roll forming system of any preceding or following example, or combination of examples, wherein the in-line heater is configured to heat at least the seam region at a temperature of from 300°C to 550°C for a duration of from greater than 0 seconds to less than or equal to 30 seconds.

[0066] Example 18. A roll forming system as described in any preceding or following example or combination of examples, wherein the forming station includes a plurality of forming stations, each forming station including at least one roller.

[0067] Example 19. The roll forming system of any preceding or following example, or combination of examples, wherein the in-line heater is rotatable about the intermediate hollow body while the intermediate hollow body is held stationary.

[0068] Example 20. The roll forming system of any preceding or subsequent example or combination of examples, wherein the intermediate hollow body is received within the in-line heater and is configured to be held stationary while rotating within the in-line heater.

[0069] The above-mentioned aspects are merely possible examples of implementations and are described merely for a clear understanding of the principles of the present disclosure. Many variations and modifications can be made to the above-mentioned embodiment(s) without substantially departing from the spirit and principles of the present disclosure. All such modifications and modifications are intended to be included herein within the scope of the present disclosure, and all possible claims to individual aspects or combinations of elements or steps are intended to be supported by the present disclosure. Moreover, although specific terms are employed in the present specification and the following claims, they are used in a generic and descriptive sense only and not for the purpose of limiting the described invention or the following claims. Some of the embodiments of the present disclosure are described in [Item 1] to [Item 20] below. [Item 1] 1. A forming system for forming a final hollow body from a metal strip, comprising: a forming station configured to receive the metal strip in a planar configuration and bend the metal strip into a desired cross-section such that longitudinal edges of the metal strip are in abutment, the forming station including at least one roller; a joining station downstream from the forming station and configured to weld the abutting longitudinal edges together into a seam region to form an intermediate hollow body; an in-line heater downstream from the bonding station and configured to selectively heat at least the seam area of ​​the intermediate hollow body; a hydroforming station downstream from the in-line heater and configured to hydroform the intermediate hollow body into the final hollow body; The molding system. [Item 2] Item 2. The forming system of item 1, wherein the forming station includes a plurality of rollers, the forming station configured to sequentially bend the metal strip from the planar configuration. [Item 3] 2. The molding system of claim 1, wherein the in-line heater comprises at least one of a rotating magnet, an induction in-line heater, a gas-powered in-line heater, an infrared in-line heater, or an electric furnace. [Item 4] 4. The molding system of claim 3, wherein the in-line heater includes the rotating magnet, and the intermediate hollow body is movable along an axis parallel to a rotation axis of the rotating magnet. [Item 5] Item 1. The forming system of item 1, further comprising a quenching station between the joining station and the hydroforming station, the quenching station configured to selectively quench the intermediate hollow body. [Item 6] a controller communicatively coupled to the in-line heater; 2. The molding system of claim 1, wherein the controller is configured to control the in-line heater such that the in-line heater heats the intermediate hollow body at a temperature of from 300°C to 550°C. [Item 7] a controller communicatively coupled to the in-line heater; 2. The molding system of claim 1, wherein the controller is configured to control the in-line heater such that the in-line heater heats the intermediate hollow body for a duration of greater than 0 seconds to less than or equal to 30 seconds. [Item 8] 1. A method for forming a final hollow body from a metal strip, comprising the steps of: roll forming the metal strip into a desired cross-section such that the longitudinal edges of the metal strip are abutted; welding the longitudinal edges together as a seam area to form an intermediate hollow body; heating at least the seam area of ​​the intermediate hollow body; hydroforming the intermediate hollow body into the final hollow body; The method comprising: [Item 9] 9. The method of claim 8, wherein the metal strip comprises a 6000 series aluminum alloy. [Item 10] 9. The method of claim 8, further comprising quenching the intermediate hollow body prior to hydroforming the intermediate hollow body into the final hollow body. [Item 11] 9. The method of claim 8, wherein the heating comprises heating a non-seamed region portion of the intermediate hollow body. [Item 12] 9. The method of claim 8, wherein heating at least the seam area comprises heating at least the seam area at a temperature of from 300° C. to 550° C. for a duration of from greater than 0 seconds to less than or equal to 30 seconds. [Item 13] 9. The method of claim 8, wherein heating at least the seam area includes heating with at least one of a rotating magnet, an induction in-line heater, a gas-powered in-line heater, an infrared in-line heater, or an electric furnace. [Item 14] 9. The method of claim 8, further comprising controlling at least one of a hardness gradient in the seam region or a strength in the seam region prior to hydroforming by controlling at least one of a duration of the heating of the seam region or a temperature of the heating of the seam region. [Item 15] 1. A roll forming system for forming an intermediate hollow body from a metal strip, comprising: a forming station configured to receive the metal strip in a planar configuration and bend the metal strip into a desired cross-section such that longitudinal edges of the metal strip are in abutment, the forming station including at least one roller; a joining station downstream from the forming station and configured to weld the abutting longitudinal edges together into a seam region to form an intermediate hollow body; an in-line heater downstream from the bonding station and configured to selectively heat at least the seam area of ​​the intermediate hollow body; a cooling station downstream from the in-line heater and configured to quench the intermediate hollow body; The roll forming system comprising: [Item 16] 20. The roll forming system of claim 15, wherein the in-line heater comprises at least one of a rotating magnet, an induction in-line heater, a gas-powered in-line heater, an infrared in-line heater, or an electric furnace. [Item 17] Item 16. The roll forming system of item 15, wherein the in-line heater is configured to heat at least the seam area at a temperature of from 300° C. to 550° C. for a duration of from greater than 0 seconds to less than or equal to 30 seconds. [Item 18] Item 16. The roll forming system of item 15, wherein the forming station includes a plurality of forming stations, each forming station including at least one roller. [Item 19] Item 16. The roll forming system of item 15, wherein the in-line heater is rotatable about the intermediate hollow body while the intermediate hollow body is held stationary. [Item 20] Item 16. The roll forming system of item 15, wherein the in-line heater is configured to be held stationary while the intermediate hollow body is received within and rotated within the in-line heater.

Claims

1. 1. A forming system for forming a final hollow body from a metal strip, comprising: a forming station configured to receive the metal strip in a planar configuration and bend the metal strip into a desired cross-section such that longitudinal edges of the metal strip are in abutment, the forming station including at least one roller; a joining station downstream from the forming station and configured to weld the abutting longitudinal edges together into a seam region to form an intermediate hollow body; an in-line heater downstream from the bonding station and configured to selectively heat at least the seam area of ​​the intermediate hollow body; a hydroforming station downstream from the in-line heater and configured to hydroform the intermediate hollow body into the final hollow body; a controller communicatively coupled to the in-line heater; Including, the controller is configured to control the in-line heater such that the in-line heater heats the intermediate hollow body at a temperature between 300° C. and 550° C.; the controller is configured to control the in-line heater such that the in-line heater heats the intermediate hollow body for a duration of greater than 0 seconds to less than or equal to 30 seconds. The molding system.

2. The forming system of claim 1 , wherein the forming station includes a plurality of rollers, the forming station configured to sequentially bend the metal strip from the planar configuration.

3. The molding system of claim 1 , wherein the in-line heater comprises at least one of a rotating magnet, an induction in-line heater, a gas-powered in-line heater, an infrared in-line heater, or an electric furnace.

4. The molding system of claim 3 , wherein the in-line heater includes the rotating magnet, and the intermediate hollow body is movable along an axis parallel to an axis of rotation of the rotating magnet.

5. The forming system of claim 1 , further comprising a quenching station between the bonding station and the hydroforming station, the quenching station configured to selectively quench the intermediate hollow body.

6. 1. A method for forming a final hollow body from a metal strip, comprising the steps of: roll forming the metal strip into a desired cross-section such that the longitudinal edges of the metal strip are abutted; welding the longitudinal edges together as a seam area to form an intermediate hollow body; heating at least the seam area of ​​the intermediate hollow body; hydroforming the intermediate hollow body into the final hollow body; Including, Heating at least the seam area includes heating at least the seam area at a temperature of from 300° C. to 550° C. for a duration of from greater than 0 seconds to less than or equal to 30 seconds. The method.

7. The method of claim 6 , wherein the metal strip comprises a 6000 series aluminum alloy.

8. The method of claim 6 further comprising quenching the intermediate hollow body prior to hydroforming the intermediate hollow body into the final hollow body.

9. The method of claim 6 , wherein the heating comprises heating a non-seamed area portion of the intermediate hollow body.

10. The method of claim 6 , wherein heating at least the seam area comprises heating with at least one of a rotating magnet, an induction in-line heater, a gas-powered in-line heater, an infrared in-line heater, or an electric furnace.

11. 7. The method of claim 6, further comprising controlling at least one of a hardness gradient in the seam region or a strength in the seam region prior to hydroforming by controlling at least one of a duration of the heating of the seam region or a temperature of the heating of the seam region.

12. 1. A roll forming system for forming an intermediate hollow body from a metal strip, comprising: a forming station configured to receive the metal strip in a planar configuration and bend the metal strip into a desired cross-section such that longitudinal edges of the metal strip are in abutment, the forming station including at least one roller; a joining station downstream from the forming station and configured to weld the abutting longitudinal edges together into a seam region to form an intermediate hollow body; an in-line heater downstream from the bonding station and configured to selectively heat at least the seam area of ​​the intermediate hollow body; a cooling station downstream from the in-line heater and configured to quench the intermediate hollow body; Including, the in-line heater is configured to heat at least the seam area at a temperature of from 300° C. to 550° C. for a duration of from greater than 0 seconds to less than or equal to 30 seconds; The roll forming system.

13. The roll forming system of claim 12 , wherein the in-line heater comprises at least one of a rotating magnet, an induction in-line heater, a gas-powered in-line heater, an infrared in-line heater, or an electric furnace.

14. The roll forming system of claim 12 , wherein the forming station includes a plurality of forming stations, each forming station including at least one roller.

15. The roll forming system of claim 12 , wherein the in-line heater is rotatable about the intermediate hollow body while the intermediate hollow body is held stationary.

16. The roll forming system of claim 12 , wherein the intermediate hollow body is configured to be received within the in-line heater and held stationary while the in-line heater rotates within the in-line heater.

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