Method for manufacturing frame parts formed by roll forming and frame parts formed by roll forming

Abstract

This invention provides a frame component formed by roll forming, which enables the productive manufacture of highly rigid frame components having multiple closed cross-sections, and also allows for the suppression of springback using a simple method, thereby improving welding accuracy, as well as a method for manufacturing the same. [Solution] The process includes a cutting step S1 for cutting a metal plate, a forming step S2 for forming a frame component having a long hollow body with at least two continuous closed cross-sections by roll forming, a temporary joining step S3 for performing a temporary joining process, a waiting step S4 for keeping the frame component awaited, and a final joining step S5 for welding the frame component. The temporary joining process is a joining process that holds overlapping plate materials in a close-contact state. In the final joining step S5, one end of the plate material or another end is continuously welded to the closed cross-section plate material along the longitudinal direction of the long hollow body. While the frame component is being formed in the forming step S2, the welding in the final joining step S5 is performed on the other frame component.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a frame component formed by roll forming and a frame component manufactured by this manufacturing method.

Background Art

[0002] Parts mounted on vehicles such as automobiles need to be supported by strong frame components. In order to increase the rigidity of the frame component, it is conceivable to provide a closed cross-sectional portion in which a plurality of frames having a square cross-section are continuously arranged in the frame component. Such frame components are described in, for example, Patent Document 1 and Patent Document 2. Patent Document 1 discloses a frame component 1 manufactured by roll forming as shown in FIGS. 35 and 36. As shown in FIG. 35, the partition wall 2 of the frame component 1 partitions a plurality of closed cross-sections (the first closed cross-section 3 and the second closed cross-section 4), and forms a contact portion 6 having a T-shaped cross-section in cooperation with the first vertical wall 5. When the partition wall 2 is inclined with respect to the first vertical wall 5 due to an error during molding or springback, etc., it may not be positioned and may not be in a surface contact state. Therefore, as shown in FIG. 36, a fitting portion 8 into which the partition wall 2 fits is formed on the first vertical wall 5.

[0003] Patent Document 2 discloses an automobile bumper. The frame component disclosed in this Patent Document 2 is formed by bending a single plate material into a substantially B-shaped cross-section by roll forming. One end and the other end of the plate material are abutted at the lowest part of the B shape and are welded by high-frequency welding. Also, the middle part in the vertical direction of the B shape is formed as a concave portion that is opened toward the left side of the B shape. The bottom part of this concave portion has the plate materials overlapped and is spot welded.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] In the frame component 1 disclosed in Patent Document 1, when the plate thickness is thick, it is easy to position the component by fitting it together using T-shaped abutments or grooves. However, when the plate thickness is reduced from the viewpoint of weight reduction, the material becomes more prone to bending, causing the partition wall 2 to tilt. Furthermore, when the plate thickness is thin, the grooves become shallower or even more difficult to form, making positioning impossible. Furthermore, since springback can occur between roll forming and welding, potentially causing the positioning to be lost, it is desirable that the shape be maintained in a way that prevents springback from occurring between forming and welding.

[0006] In the frame component disclosed in Patent Document 2, a recess is formed in the middle of the B-shape in the vertical direction, resulting in insufficient rigidity. Therefore, it is not suitable for use as a frame to house an automobile battery. Furthermore, when welding one end to the other end of the plate material of the frame component shown in Patent Document 2 by high-frequency welding, a jig may be necessary to prevent the ends from separating due to springback and to improve welding accuracy. A box-shaped welding jig that sandwiches the frame component from both the left and right sides of the B-shape is conceivable as such. For this reason, when manufacturing frame components by roll forming, there is a need to suppress springback using a simple method to improve welding accuracy.

[0007] The object of the present invention is to provide a frame component formed by roll forming that enables the productive manufacture of a highly rigid frame component having multiple closed cross-sections, and also enables the suppression of springback by a simple method to improve welding accuracy, as well as a method for manufacturing the same. [Means for solving the problem]

[0008] To achieve this objective, the method for manufacturing a frame part formed by roll forming according to the present invention comprises: a cutting step of cutting a metal plate to a predetermined length; a forming step of forming a frame part having a long hollow body with at least two closed cross-sections arranged in a row by applying roll forming to the plate; a temporary joining step of performing a temporary joining process on the frame part to maintain the shape of the closed cross-sections; a waiting step of having the frame part wait after the temporary joining process is completed; and a final joining step of welding the frame part that has been waiting in the waiting step. The temporary joining process performed in the joining process is a joining process that holds at least one overlapping plate material in a state of close mechanical or chemical contact to the extent that the shape of the closed cross-section of the frame component is maintained. In the main joining process, one end of the initial stage of roll forming of the plate material or the other end of the final stage is continuously welded to the plate material of the closed cross-section along the longitudinal direction of the long hollow body, and while the frame component is being formed in the forming process, the welding of the main joining process is performed on the other frame component in the waiting stage.

[0009] The present invention relates to a method for manufacturing a frame component formed by roll forming, wherein the temporary joining treatment may be performed on at least one end or the other end located outside the closed cross-section while maintaining the hollow shape of the frame component.

[0010] The present invention relates to a method for manufacturing a frame component formed by roll forming, wherein a drilling step is performed before the forming step to drill rivet holes in the plate material at the positions where the temporary joining process is to be performed, and the temporary joining step is performed by driving rivets into the rivet holes using a rivet driving device installed downstream of the roll forming apparatus that performs the forming step in the feeding direction of the frame component.

[0011] The present invention relates to a method for manufacturing frame parts formed by roll forming, wherein the temporary joining step may be performed by driving in a flow drill screw using a flow drill screw driving device installed downstream of the roll forming apparatus performing the forming step in the feeding direction of the frame parts.

[0012] The present invention relates to a method for manufacturing a frame component formed by roll forming, wherein a concave shaping step is performed before or during the forming step to form a concave shaping portion in the plate material at a position where the temporary joining process is performed, and the temporary joining process in the temporary joining step is performed on the concave shaping portion.

[0013] The present invention relates to a method for manufacturing a frame component formed by roll forming, wherein the depth of the recess of the recessed portion formed in the recessed shape forming step may be the same as or deeper than the height of the head of the temporary joining means that performs the temporary joining process.

[0014] The present invention relates to a method for manufacturing a frame component formed by roll forming, wherein in the forming step, forming stress is applied so that the frame component undergoes compressive deformation, and the temporary joining process in the temporary joining step may be performed when the frame component has returned to its normal shape due to springback caused by the forming stress.

[0015] The frame component formed by roll forming according to the present invention is a frame component having a long hollow body in which at least two closed cross-sections are arranged in a continuous line, formed by roll forming a plate material, wherein the frame component has a close-contact portion in which at least one overlapping plate material is joined to maintain the shape of the closed cross-sections by mechanically or chemically holding them in close contact, and a welded portion which is continuously welded to the closed cross-sections along the longitudinal direction of the long hollow body at one end in the initial stage of roll forming of the plate material or at the other end in the final stage.

[0016] In the frame component formed by the roll forming, the close contact part may be in a close contact state by any one of a rivet, a flow drill screw, an adhesive, and a clamp.

[0017] In the frame component formed by the roll forming, the close contact part has a concave-shaped part, and the joining means for performing the joining process may not protrude.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a flowchart for explaining an embodiment of a method for manufacturing a frame component formed by roll forming according to the present invention. [Figure 2] FIG. 2 is a side view of a roll forming machine. [Figure 3] FIG. 3 is a block diagram showing the configuration of a storage location and the present welding machine. [Figure 4] FIG. 4 is a cross-sectional view of a frame component. [Figure 5] FIG. 5 is a perspective view of a frame component. [Figure 6] FIG. 6 is a cross-sectional view of a plate material showing the roll forming process step by step. [Figure 7] FIG. 7 is a cross-sectional view of a plate material showing the roll forming process step by step. [Figure 8] FIG. 8 is a cross-sectional view of a plate material showing the roll forming process step by step. [Figure 9] FIG. 9 is a cross-sectional view for explaining springback. [Figure 10] FIG. 10 is a cross-sectional view of a frame component in which a temporary joining process has been performed. [Figure 11] FIG. 11 is a flowchart showing a method for manufacturing a frame component having a perforation process. [Figure 12] FIG. 12 is a cross-sectional view for explaining the temporary joining process. [Figure 13]Figure 13 is a cross-sectional view of a frame component compressed during the molding process. [Figure 14] Figure 14 is a front view showing the position of the rivet holes when the compression deformation is restored. [Figure 15] Figure 15 is a cross-sectional view illustrating the shape of the penetration area achieved by laser welding. [Figure 16] Figure 16 is a perspective view of the frame component after this joining process has been completed. [Figure 17] Figure 17 is a perspective view of a frame component in which laser welding has been performed between multiple temporary joints. [Figure 18] Figure 18 is a side view of a roll forming machine that performs a method for manufacturing frame components in which the cutting process is carried out after the temporary joining process. [Figure 19] Figure 19 is a flowchart illustrating a method for manufacturing frame components in which the cutting process is performed after the temporary joining process. [Figure 20] Figure 20 is a cross-sectional view of a frame component that has been temporarily joined using a flow-drill screw. [Figure 21] Figure 21 is a cross-sectional view of a frame component immediately before performing temporary joining using a flow drill screw. [Figure 22] Figure 22 is a side view of a roll forming machine that performs temporary joining using a flow drill screw. [Figure 23] Figure 23 is a cross-sectional view of a frame component in which a flow drill screw has not been driven into the concave portion. [Figure 24] Figure 24 is a cross-sectional view of a frame component in which a flow drill screw has been driven into a concave portion. [Figure 25] Figure 25 is a cross-sectional view of a frame component with blind rivets attached to a recessed area. [Figure 26] Figure 26 is a flowchart illustrating a method for manufacturing frame components in which the concave shape forming process is performed before the molding process. [Figure 27]Figure 27 is a flowchart illustrating a method for manufacturing a frame component that performs a concave shape molding process during the molding process. [Figure 28] Figure 28 is a perspective view of a frame component that has been welded through a section that has undergone temporary joining treatment. [Figure 29] Figure 29 is a magnified cross-sectional view showing a portion of a frame component that has been welded through a section where temporary joining treatment was performed. [Figure 30] Figure 30 is a perspective view of a frame component that has been temporarily joined using clamps that hold the overlapping parts of the plate materials. [Figure 31] Figure 31 is a front view of a frame component that has been temporarily joined using clamps that hold the overlapping parts of the plate materials. [Figure 32] Figure 32 is a front view of a frame component that has been temporarily joined using clamps that hold the entire frame component. [Figure 33] Figure 33 is a cross-sectional view showing another example of a frame component. [Figure 34] Figure 34 is a cross-sectional view showing another example of a frame component. [Figure 35] Figure 35 is a cross-sectional view of a conventional frame component. [Figure 36] Figure 36 is a cross-sectional view showing a magnified portion of a conventional frame component. [Modes for carrying out the invention]

[0019] (First Embodiment) Hereinafter, a method for manufacturing frame parts formed by roll forming according to the present invention and an embodiment of the frame parts will be described in detail with reference to Figures 1 to 17. (A brief explanation of the manufacturing method for frame components) The method for manufacturing frame parts formed by roll forming according to this embodiment is as shown in the flowchart of Figure 1, and involves performing the cutting step S1, the forming step S2, the temporary joining step S3, the waiting step S4, and the final joining step S5 in that order. Frame parts manufactured by this method can be used as parts for supporting on-board parts of automobiles and the like (not shown), or as parts that constitute a part of the frame of a vehicle body.

[0020] The cutting process S1, the forming process S2, and the temporary joining process S3 are carried out by the roll forming machine 11 shown in Figure 2. The waiting process S4 is carried out in the storage area 12 (see Figure 3), and the main joining process S5 is carried out by the main welding machine 13 (see Figure 3). The roll forming machine 11 feeds a metal sheet 15 from the cutting device 14, located on the far left in Figure 2, to the right in Figure 1, thereby manufacturing a product of a predetermined shape. The cutting device 14 is a device for performing the cutting process S1. This cutting device 14 has the function of cutting a metal sheet 15 having a predetermined width to a predetermined length, the function of performing perforation, grooving, and pressing on the sheet 15, and the function of feeding the sheet 15 to the downstream side in the feeding direction.

[0021] A multi-stage roll forming machine 16 is positioned downstream of the cutting device 14 in the feeding direction of the sheet material 15, and a temporary joining device 17 is positioned downstream of the multi-stage roll forming machine 16 in the feeding direction of the sheet material 15. The multi-stage roll forming machine 16 is a device for carrying out the forming process S2. In this embodiment, the multi-stage roll forming machine 16 corresponds to the "roll forming device" as defined in the present invention. This multi-stage roll forming machine 16 uses a number of rolls 16a to bend the sheet metal 15 into a predetermined shape by roll forming, forming the frame parts 18 shown in Figures 4 and 5. Figure 4 shows a cross-sectional view when the frame part 18 is cut along the virtual plane A shown in Figure 5. The virtual plane A shown in Figure 5 is hatched downwards to the left. The frame part 18 has a hollow body 19 that is formed to be elongated, although this will be described in detail later. Roll forming will be explained later.

[0022] The temporary joining device 17 is a device for performing the temporary joining process S3. This temporary joining device 17 performs a temporary joining process on the frame component 18 formed by the multi-stage roll forming machine 16 so as to maintain its shape. The temporary joining process performed in the temporary joining process S3 is a joining process that holds at least one overlapping plate material 15 together in a state where they are mechanically or chemically in close contact to the extent that the shape of the closed cross-section of the frame component 18, described later, is maintained. The temporary joining device 17 in this embodiment is composed of a rivet driving device 20. The temporary joining process in this embodiment is riveting of the overlapping portions of the plate materials 15. A detailed explanation of the temporary joining process will be given later.

[0023] After the temporary joining process by the temporary joining device 17 is completed, the frame parts 18 are removed from the roll forming machine 11 and moved to the storage area 12. The multi-stage roll forming machine 16 continuously produces frame parts 18 after the temporary joining process is completed. Therefore, as shown in Figure 3, multiple frame parts 18 are stored in the storage area 12 to await processing in the next process, the main joining process S5. This process in which the frame parts 18 await the next process in the storage area 12 is called the waiting process S4. In this joining process S5, the frame components 18 waiting in the storage area 12 are supplied to the welding machine 13, and the frame components 18 are subjected to this joining process which restricts changes in shape. In this joining process S5, one end 21 (see Figure 4) from the initial stage of roll forming of the plate material 15, or the other end 22 from the final stage, is continuously welded to the closed section of the plate material 15 along the longitudinal direction of the long hollow body 19 (continuous welding is performed). One end 21 includes one end 23 of the plate material, and the other end 22 includes the other end 24 of the plate material. In this embodiment, the joining process S5 involves laser welding. A detailed explanation of laser welding will be given later.

[0024] (Detailed explanation of the manufacturing method of frame components) (Explanation of molding process S2) The frame component 18 shown in Figure 4 is a frame component 18 having a long hollow body 19 in which three closed cross-sections 25 to 27 are arranged in a continuous line, formed by roll forming a plate material 15. In the following description of each part of the frame component 18, for convenience, the upper part of Figure 4 will be referred to as the upper part of the frame component 18, and the left side of Figure 4 will be referred to as the left side of the frame component 18.

[0025] In the frame component 18 according to this embodiment, a single sheet of material 15 is bent by roll forming, so that the plate-like portions of the sheet material 15 overlap in the thickness direction at three locations. The frame component 18 shown in Figure 4 is provided with first to third double wall portions 28 to 30 in which portions of the sheet material 15 are aligned in a direction perpendicular to the direction in which the first to third closed cross-sectional portions 25 to 27 are aligned (left to right direction in Figure 4).

[0026] The first double wall section 28 includes one end 21 which is formed in the initial stage of roll forming. The second double wall section 29 includes the other end 22 which is formed in the final stage of roll forming. The one end 21 and the other end 22 extend vertically across the frame component 18. The third double wall section 30 is located between the first double wall section 28 and the second double wall section 29 in the vertical direction of the frame component 18. In this frame component 18, although details will be described later, the second double wall portion 29 and the third double wall portion 30 are temporarily joined in the temporary joining process S3, and the first double wall portion 28 is laser-welded in the main joining process S5.

[0027] In this embodiment, roll forming is carried out so as to form first and second closed cross-sections 25, 26 including a first double-walled section 28 and a third double-walled section 30, and a third closed cross-section 27 including a second double-walled section 29. When forming the first to third closed cross-sections 25 to 27, first, in the initial stages of roll forming, a ladle-shaped section 31 with a ladle-shaped cross-section including one end 21 of the sheet material 15 is formed. The ladle-shaped portion 31 has one end 23 of the plate material 15 and is composed of a first horizontal wall 32 extending to the left in Figure 4 from the aforementioned end 21, a first vertical wall 33 extending downward from the left end of the first horizontal wall 32, a second horizontal wall 34 extending to the right from the lower end of the first vertical wall 33, and a second vertical wall 35 extending downward from the right end of the second horizontal wall 34. The ladle-shaped portion 31 is formed such that one end 23 of the plate material 15 is located at the open end of the ladle, the first vertical wall 33 becomes the bottom of the ladle, and the second vertical wall 35 becomes the handle of the ladle.

[0028] In this embodiment, the frame component 18 has three closed sections (first to third closed sections 25 to 27). Therefore, after forming the ladle-shaped section 31, the outer frame 36 is formed so that the first to third closed sections 25 to 27 are formed in cooperation with the ladle-shaped section 31. The outer frame 36 includes an outer frame section 37 with a cup-shaped cross section that accommodates the ladle of the ladle-shaped section 31. The outer frame section 37 is the part that cooperates with the ladle of the ladle-shaped section 31 to form the first and second closed sections 25 and 26.

[0029] The outer frame 36 is formed to surround the ladle-shaped portion 31, extending from the lower end of the second vertical wall 35 (the tip of the ladle handle) through the bottom side of the ladle and the opening side of the ladle. More specifically, the outer frame 36 is formed by a third horizontal wall 38 extending to the left from the lower end of the second vertical wall 35, a third vertical wall 39 extending upward from the left end of the third horizontal wall 38 and overlapping with the first vertical wall 33, a fourth horizontal wall 40 extending to the right from the upper end of the third vertical wall 39, and a fourth vertical wall 41 extending downward from the right end of the fourth horizontal wall 40 and overlapping with one end 21 of the plate material 15 and the second vertical wall 35. The outer frame portion 37 is composed of a third vertical wall 39, a fourth horizontal wall 40, and a fourth vertical wall 41.

[0030] The molding sequence when forming the frame component 18 shown in Figure 4 by the roll forming method is as shown in Figures 6(A)-(G), 7(A)-(D), and 8(A)-(D). Roll forming is performed using the multi-stage roll forming machine 16 of the roll forming machine 11 shown in Figure 1. Figures 6(A)-(G), 7(A)-(D), and 8(A)-(D) are cross-sectional views of the plate material 15 as seen from the longitudinal direction.

[0031] To form the frame component 18, first, the ladle-shaped portion 31 is formed as shown in Figures 6(A) to 7(B). That is, one end 21, including one end 23 of the flat plate material 15, is bent, then the first horizontal wall 32 is bent, and the first vertical wall 33, second horizontal wall 34, and second vertical wall 35 are formed in this order. The radius of curvature of the curved portion 42 (see Figure 4) between each wall can be adjusted by the multi-stage roll forming machine 16 according to the rigidity and collision performance. Then, as shown in Figures 7(C) to 8(D), the third horizontal wall 38, third vertical wall 39, fourth horizontal wall 40, and fourth vertical wall 41 are formed in this order. When the third vertical wall 39 is formed and overlaps with the first vertical wall 33, the third double wall portion 30 is formed.

[0032] More specifically, in the process shown in Figure 7(D), the third vertical wall 39 and the first vertical wall 33 are overlapped to form a double wall. Then, in the processes shown in Figures 8(A) to (B), the third vertical wall 39 is bent to form a curved portion 42, thereby forming the fourth horizontal wall 40. Subsequently, in the processes shown in Figures 8(C) to (D), the fourth vertical wall 41 is overlapped with one end 21 of the plate material 15 and the second vertical wall 35 to form the first and second double wall portions 28 and 29. After overlapping the third vertical wall 39 with the first vertical wall 33 in the process shown in Figure 7(D), an additional step can be added in which the third vertical wall 39 is bent to the left in the figure, as shown in Figure 7(E), to form a rectangular cross-section frame 36a on the upper left side of the outer perimeter frame 36 in the figure.

[0033] This rectangular cross-section frame 36a is formed by bending the third vertical wall 39 clockwise in the figure, and finally, the third vertical wall 39 is formed so that it extends downward and overlaps with the part bent to the left as described above, and a closed cross-section is added to the outside. After forming the rectangular cross-section frame 36a in this way, the third vertical wall 39 is bent so that its tip points to the right in the figure, resulting in the state shown in Figure 8(B). When roll forming is performed in this manner, springback occurs in the curved portion 42, and the frame component 18 may deform after forming as shown in Figure 9. When springback occurs, the fourth vertical wall 41 separates from one end 21 of the plate material 15 and the second vertical wall 35, and the first vertical wall 33 separates from the third vertical wall 39. When deformation occurs in this manner, laser welding of the first double wall portion 28 becomes impossible in a subsequent process. To prevent such deformation due to springback, a temporary joining process S3 is performed after the forming process S2.

[0034] (Explanation of temporary joining process S3) In this frame component 18, the fourth vertical wall 41, including the other end 22 of the plate material 15, is connected to the fourth horizontal wall 40 at a single bending point 43 located in a position enclosed by a virtual circle made of a dashed line in Figure 9. Therefore, it is more susceptible to warping due to springback than a wall sandwiched between two bending points (for example, the third vertical wall 39). In particular, when the final shape is reached (a shape with two or three consecutive closed sections of a rectangular cross-section), if one end 23 or the other end 24 of the plate material 15 is outside the closed section, there is a high possibility that it will become more open than the normal shape due to springback. For this reason, the temporary joining process S3 is performed on the end located outside the closed section while at least the hollow shape of the frame component 18 is maintained. In the frame component 18 according to this embodiment, since the other end 22 is located outside the closed section, it is necessary to perform the temporary joining process on the second double wall section 29.

[0035] In this embodiment, the temporary joining process S3 is carried out by performing a temporary joining process on the third double wall portion 30, where the outer frame portion 37 (third vertical wall 39) overlaps the bottom of the ladle (first vertical wall 33) of the ladle-shaped portion 31, and the second double wall portion 29, where the outer frame portion 37 (fourth vertical wall 41) overlaps the handle of the ladle (second vertical wall 35). In this embodiment, the second double wall portion 29 and the third double wall portion 30 correspond to the "closely joined portion" as defined in the present invention. In this embodiment, the temporary joining process S3 is carried out using a rivet driving device 20 installed downstream of the multi-stage roll forming machine 16 that performs the molding process S2 in the feeding direction of the frame component 18.

[0036] The rivet-driving device 20 performs rivet joining using blind rivets 44, as shown in Figure 10. Figure 10 is a cross-sectional view of the frame component 18 shown in Figure 5 when cut along a virtual plane B. The virtual plane B shown in Figure 5 is hatched downwards to the right. The rivet joining is performed by inserting the blind rivets 44 into the rivet holes 45 of the frame component 18 from the outside of the frame component 18. The rivet holes 45 can be drilled at predetermined positions in the plate material 15 by the cutting device 14. That is, the cutting process S1 according to this embodiment is carried out including a drilling process S1A for drilling rivet holes 45, as shown in Figure 11.

[0037] The rivet holes 45 consist of outer rivet holes 45a formed in the outer frame portion 37 (third and fourth vertical walls 39, 41) of the frame component 18, and inner rivet holes 45b formed in the first and second vertical walls 33, 35. The diameter of the outer rivet holes 45a is larger than the diameter of the inner rivet holes 45b. As shown in Figures 12(A) to (C), the blind rivet 44 is composed of a cylindrical body portion 46 and a shaft portion 47 that is movably inserted into the body portion 46. A flange 46a is provided at one end of the body portion 46. The shaft portion 47 passes through the body portion 46. At the end of the shaft portion 47 that protrudes on the side opposite to the flange 46a of the body portion 46, a head 47a is provided, having an outer diameter equal to the outer diameter of the body portion 46.

[0038] In order to perform the temporary joining process S3 using this blind rivet 44, first, as shown in Figure 12(A), the blind rivet 44 is inserted into the rivet hole 45 from the outside of the frame part 18, and the shaft portion 47 is pulled toward the outside of the frame part 18 while the flange 46a is pressed against the third and fourth vertical walls 39 and 41. As the shaft portion 47 is pulled in this way, the tip 46b of the main body portion 46 is pushed open by the head 47a, as shown in Figure 12(B). After that, the shaft portion 47 is pulled further by a predetermined length, and with the tip 46b of the main body portion 46 significantly deformed as shown in Figure 12(C), the shaft portion 47 is cut at the portion protruding from the flange 46a. By performing this temporary joining process, subsequent deformation due to springback is restricted, and one end 21 of the plate material 15 is held in a state where it overlaps with the fourth vertical wall 41 in the first double wall section 28.

[0039] Springback begins when the forming process by the multi-stage roll forming machine 16 is completed. Therefore, springback that occurs before the temporary joining process is carried out may cause misalignment between the outer rivet hole 45a and the inner rivet hole 45b. In this embodiment, the outer rivet hole 45a is formed to have a larger diameter than the inner rivet hole 45b, so a wider tolerance range can be given for misalignment due to springback.

[0040] To prevent the outer rivet hole 45a from shifting relative to the inner rivet hole 45b due to springback occurring before the temporary joining process is carried out, it is conceivable to apply forming stress during roll forming so that the frame component 18 is compressed and deformed beyond its normal shape. That is, when forming the outer frame 36 of the frame component 18, a part of the frame component 18 is elastically deformed as shown in Figure 13, and then formed to its normal shape during the springback process due to stress release after forming. In the frame component 18 shown in Figure 13, the first and second side walls 32 and 34 of the ladle-shaped part 31 are inclined downward to the right, and the lower part of the frame component 18 is deformed as if it has been crushed in the left-right direction due to compression. In Figure 13, the frame component 18 is depicted as being more deformed than it actually is in order to make the deformation easier to understand.

[0041] By performing roll forming in a manner that takes into account stress release after forming, the frame component 18 is restored to its original shape, i.e., the shape shown in Figure 4, due to springback caused by stress release after forming. When the frame component 18 is compressed and deformed by roll forming, immediately after forming, the outer rivet hole 45a and the inner rivet hole 45b are misaligned, as shown in Figure 14(A). However, when the frame component 18 is restored to its original shape by springback, the misalignment between the outer rivet hole 45a and the inner rivet hole 45b is resolved, as shown in Figure 14(B). By performing a temporary joining process at this time, rivet joining with blind rivets 44 is correctly performed.

[0042] To perform riveting in this manner, the temporary joining device 17 should be positioned so that the frame component 18 returns to its normal shape while being sent from the multi-stage roll forming machine 16 to the temporary joining device 17. To achieve this, the distance D (see Figure 2) between the multi-stage roll forming machine 16 and the temporary joining device 17 can be set to the distance the frame component 18 travels while returning to its normal shape after forming. By adopting this configuration, the temporary joining process is performed when the frame component 18, which has been compressed and deformed by roll forming, returns to its normal shape due to springback caused by stress release.

[0043] (Explanation of the joining process S5) The main joining process S5 is carried out by sequentially feeding the frame parts 18, which have undergone temporary joining and been moved to the storage area 12, into the main welding machine 13. That is, in the main joining process S5, while the frame parts 18 are being formed in the forming process S2, laser welding is performed on the other frame parts 18 waiting in the waiting process S4 (other frame parts 18 in the waiting process S4). The laser welding is performed consistently on the frame parts 18 waiting in the waiting process S4 using the same welding method. In this joining process S5, it is desirable to perform laser welding on multiple frame components 18 simultaneously using multiple welding machines 13. This is because laser welding requires a longer working time compared to roll forming, and productivity can be increased by performing laser welding on multiple frame components 18 simultaneously. Laser welding is performed by irradiating the first double wall portion 28 with laser light L from the outside of the frame component 18 (from the opposite side of the end portion 21), as shown in Figure 15.

[0044] The laser beam L is shone onto the outer surface 41a of the fourth vertical wall 41 at a position corresponding to the end 21. When the laser beam L is shone onto the first double wall portion 28 in this way, a part of the fourth vertical wall 41 and a part of the end 21 melt and mix together, and they are welded together. As a result of the laser welding, a bullet-shaped penetration portion 48 is created, which is shown in Figure 15 with hatching that slopes downward to the left. The bullet shape of the penetration portion 48 is a convex shape that extends from the laser irradiation surface (outer surface 41a) toward the end 21. Due to the bullet-shaped penetration portion, the first horizontal wall 32 is more likely to bend under load from the direction of laser irradiation, and as the first horizontal wall 32 bends, the load tends to concentrate on the curved portion 42, increasing the amount of impact absorption.

[0045] Laser welding is performed continuously from one end to the other in the longitudinal direction of the frame component 18, as indicated by the reference numeral 49 in Figure 16. Upon completion of this joining process S5, the frame component 51 with its final shape, whose shape changes are restricted, is completed. Laser welding can also be performed at positions adjacent to the blind rivets 44 driven by the rivet driving device 20 in the temporary joining process S3 and the frame component 18 in the longitudinal direction, as shown in Figure 17. In the frame component 18 shown in Figure 23, laser welding is performed so that a linear welded section 52 is formed between multiple temporary joining sections (blind rivets 44) that are arranged at predetermined intervals in the longitudinal direction.

[0046] (Explanation of the effects according to the first embodiment) The method for manufacturing a frame component 18 formed by roll forming according to this embodiment includes a cutting step S1 of cutting a metal plate material 15 to a predetermined length, a forming step S2 of forming a frame component 18 having a long hollow body 19 in which first to third closed cross-sections 25 to 27 are arranged in a continuous line by applying roll forming to the plate material 15, a temporary joining step S3 of performing a temporary joining process on the frame component 18 to maintain the shape of the closed cross-sections, a waiting step S4 of having the frame component 18 wait after the temporary joining process is completed, and a final joining step S5 of welding the frame component 18 that was waiting in the waiting step S4. The temporary joining process performed in the temporary joining step S3 is a joining process that holds at least one overlapping plate material 15 together in a state where they are mechanically close to each other to the extent that the shape of the closed cross-sections of the frame component 18 is maintained. In this joining process S5, one end 21 of the plate material 15 in the initial stage of roll forming is continuously welded to the closed section of the plate material 15 along the longitudinal direction of the long hollow body 19. While the frame component 18 is being formed in the forming process S2, the welding in this joining process S5 is performed on the other frame component 18 in the waiting process S4.

[0047] According to this manufacturing method, when welding is performed in the joining process S5, the contact area is increased compared to when welding is performed at the butt joint, resulting in surface contact, which allows for easy and accurate welding. Since temporary joining is performed with blind rivets 44, one-sided joining is possible, and temporary fastening is possible even for complex closed cross-sections. In addition, the laser welding time is longer than the roll forming time because complex shapes are welded. However, by providing a waiting process S4 as shown in this embodiment, production can be carried out without reducing the roll forming speed, thus improving productivity. Furthermore, the accuracy of laser welding after roll forming can be improved by using a simple method that does not require the use of box-type welding jigs, etc.

[0048] The frame component 18 formed by roll forming according to this embodiment is a frame component 18 having a long hollow body 19 in which first to third closed cross-sections 25 to 27 are arranged in a continuous line, formed by roll forming a plate material 15. This frame component 18 has a close-contact portion (second and third double-wall portions 29, 30) which is joined to hold at least one overlapping plate material in a mechanically close contact state so as to maintain the shape of the closed cross-sections, and a welded portion 49 which is continuously welded to the plate material of the closed cross-section along the longitudinal direction of the long hollow body 19 at one end 21 in the initial stage of roll forming of the plate material. This frame component 18 is a highly rigid frame component having multiple closed cross-sections.

[0049] Therefore, according to this embodiment, it is possible to manufacture a highly rigid frame component 18 having multiple closed cross-sections with high productivity, and to provide a frame component 18 formed by roll forming and a method for manufacturing the same that can suppress springback with a simple method and improve welding accuracy. The welding performed in this joining process S5 can be performed on the second double wall portion 29 instead of the first double wall portion 28. That is, in this joining process, one end portion 21 in the initial stage of roll forming of the plate material 15 or the other end portion 22 in the final stage is continuously welded to the plate material 15 of the closed cross-section along the longitudinal direction of the long hollow body 19.

[0050] The temporary joining process is performed on one end 21 or other end 22 located outside the closed section while maintaining at least the hollow shape of the frame component 18. Therefore, by temporarily joining the wall that overlaps with a wall containing a portion prone to warping due to springback (one end or the other end of a plate), springback can be suppressed.

[0051] In this embodiment, a drilling step S1A is performed to drill rivet holes 45 in the plate material 15 at the positions where temporary joining treatment is to be performed before the molding step S2. The temporary joining step S3 is performed by driving blind rivets 44 into the rivet holes 45 using a rivet driving device 20 installed downstream of the multi-stage roll forming machine 16 that performs the molding step S2 in the feeding direction of the frame component 18. Blind rivets 44 can be driven in from one side and can join even closed sections. Furthermore, they allow for faster joining compared to laser welding (main welding), enabling the frame component 18 to maintain its proper shape more quickly. Additionally, when riveting from both sides, the tack-fastening time can be reduced.

[0052] In this embodiment, the roll forming process S2 involves applying forming stress so that the frame component 18 undergoes compressive deformation, as shown in Figure 13. The temporary joining process S3 is performed when the frame component 18 has returned to its normal shape due to springback caused by stress release. According to this embodiment, since the product is temporarily fixed in the correct position, subsequent laser welding can maintain the product shape.

[0053] In this embodiment, the close contact portions of the frame component 18 (the second double wall portion 29 and the third double wall portion 30) are in close contact with each other by blind rivets 44. Therefore, even in the first double wall section 28 where laser welding is performed, the overlapping portions of the plate material 15 are in close contact, and since the plate material 15 of this first double wall section 28 is laser-welded in close contact with each other, the frame component 18 has high welding strength.

[0054] In this embodiment, the joining process S5 is carried out by welding the first double wall portion 28 to the outside of the frame component 18 by laser welding. Although one end 21 of the plate material 15 is located inside the closed cross-section, laser welding allows welding from one side of the frame component 18. Therefore, a frame component 18 with high rigidity can be manufactured.

[0055] In this embodiment, if laser welding is also performed at positions adjacent to the blind rivet 44 and the frame component 18 in the longitudinal direction, it is possible to reliably prevent changes in the shape of the final product.

[0056] (Second Embodiment) The cutting process S1 can be performed after the molding process S2. One embodiment of this configuration is illustrated in Figures 18 and 19. In Figures 18 and 19, the same or equivalent components as those described in Figures 1 to 17 are denoted by the same reference numerals, and detailed explanations are omitted.

[0057] In this embodiment, the method for manufacturing the frame component 18 formed by roll forming is carried out using the roll forming machine 61 shown in Figure 18, as shown in the flowchart in Figure 19. The roll forming machine 61 feeds a metal sheet 15 from the uncoiler 62, located on the far left in Figure 18, to the right in Figure 18, thereby manufacturing a product of a predetermined shape. The metal sheet 15 is mounted on the uncoiler 62 in a coiled state.

[0058] Downstream from the uncoiler 62 in the feeding direction of the sheet metal 15, devices such as a pre-drilling press 63, a multi-stage roll forming machine 64, a temporary joining device 65, and a cutting machine 66 are arranged in this order. The pre-drilling press 63 performs machining operations on the sheet metal 15, such as drilling, cutting, and pressing. The rivet holes 45 can be formed by this pre-drilling press 63.

[0059] The cutting machine 66 cuts the cylindrical plate material 15 to a predetermined length after temporary joining. The cutting of the plate material 15 by the cutting machine 66 forms frame parts 18, which will become the final frame parts 51. The frame parts 18 are sent to the storage area 12 shown in Figure 3 and sequentially fed into the main welding machine 13. In this configuration, as shown in Figure 19, the cutting process S1 is performed after the molding process S2 and the temporary joining process S3 are completed, and then the waiting process S4 and the final joining process S5 are performed sequentially. That is, the cutting process S1 is performed either after the temporary joining process S3 and before the waiting process S4 as in this embodiment, or before the molding process S2 as in the embodiment described above. By performing the cutting process S1 after the temporary joining process S3, the cylindrical plate material 15 can be cut while suppressing deformation due to springback.

[0060] (Third embodiment) In the first embodiment, the temporary joining process performed on the closely spaced portions (second and third double wall portions 29, 30) is carried out using blind rivets 44 as the temporary joining means. However, the temporary joining means used when performing the temporary joining process is not limited to blind rivets 44, and as shown in Figures 20 to 32, flow drill screws 71, clamps 72, 73, etc., can be used. In Figures 20 to 32, the same or equivalent components as those described in Figures 1 to 19 are denoted by the same reference numerals, and detailed explanations are omitted as appropriate.

[0061] The closely joined portions shown in Figure 20 (the second double wall portion 29 and the third double wall portion 30) are joined by a flow drill screw 71 (hereinafter simply referred to as FDS71). The FDS71 is a screw member that rotates at high speed and is pressed against the plate material 15 (see Figure 21). When the high-speed rotating FDS71 is pressed against the plate material 15, the heat generated by the friction between the FDS71 and the plate material 15 softens the plate material 15. Then, the softened plate material 15 undergoes plastic flow to form screw threads 74, and the FDS71 is screwed into the plate material 15. After that, the screw thread shape is maintained as it cools, and the overlapping plate materials 15 are held in a closely joined state.

[0062] The temporary joining process S3 using FDS71 is performed by driving the FDS71 using a flow drill screw driving device 75 installed downstream of the frame component 18 in the feeding direction from the multi-stage roll forming machine 16 that performs the forming process S2, as shown in Figure 22. In this case, the manufacturing method of the frame component 18 can be the manufacturing method shown in the flowcharts of Figures 1 and 19. When using FDS71 in the temporary joining process S3, the number of steps can be reduced because the step of creating pilot holes (rivet holes 45) is unnecessary compared to when temporary joining is performed with blind rivets. Even when using FDS71 for temporary joining, it is possible to drive it in from one side, and joining can be performed even on closed sections. Furthermore, joining can be done faster than laser welding (final welding), and frame components can be maintained in their proper shape more quickly. In addition, when driving FDS71 into the frame component 18 from both sides in the left-right direction, the temporary fixing time can be shortened.

[0063] Even if the frame component 18 is joined with FDS71 at the close contact points, the close contact points remain in a close contact state, so laser welding is performed with the plate materials 15 in close contact with each other at the first double wall section 28. As a result, this frame component 18 also becomes a frame component with high weld strength.

[0064] When using FDS71 or blind rivets 44 as temporary joining means for the temporary joining process, a recessed portion 76 can be formed in the second and third double wall portions 29 and 30 of the plate material 15 where the temporary joining process is performed, as shown in Figure 23. FDS71 can be driven into the recessed portion 76 as shown in Figure 24, or blind rivets 44 can be driven into it as shown in Figure 25. Rivet holes 45 are pre-drilled in the recessed portion 76 shown in Figure 25, just as in the case where the recessed portion 76 is not provided.

[0065] The FDS71 shown in Figure 24 has its head 71a housed within a recessed portion 76. The recessed portion 76 is shaped to accommodate the entire head 71a of the FDS71. More specifically, as shown in Figure 23, the recess depth D of the recessed portion 76 is the same as or greater than the height H of the head 71a of the FDS71. That is, the close contact portion of the frame component 18 shown in Figure 24 (the second double wall portion 29 and the third double wall portion 30) has a recessed portion 76, and the joining means (in this case, the FDS71) used for joining does not protrude. This also applies when using blind rivets 44.

[0066] Frame components having a concave portion 76 at the location where temporary joining is performed can be manufactured, for example, by the manufacturing method shown in the flowcharts of Figures 26 and 27. Although not shown, frame components 18 using the concave portion 76 can also be manufactured even if the cutting process S1 is performed after the temporary joining process S3, as shown in the flowchart of Figure 19. That is, a concave shape forming process S6 is performed before or during the molding process S2 to form a concave portion 76 at the location where temporary joining is performed on the plate material 15, and then temporary joining is performed on the concave portion 76 in the temporary joining process S3. If the concave shape forming process S6 is performed before the molding process S2, a cutting device 14 or a pre-drill press 63 installed upstream of the multi-stage roll forming machine 16 that performs the molding process S2 in the feed direction of the frame component 18 is used. In this case, the concave portion 76 is formed as a circular recess, for example. If the concave shape forming process S6 is performed during the molding process, multi-stage roll forming machines 16 and 64 are used. In this case, the concave portion 76 is formed as a groove extending in the longitudinal direction of the frame component 18.

[0067] By creating a recessed shape consisting of a concave portion 76 at the location where the temporary joining process is to be performed, the recessed shape serves as a landmark when determining the location for the temporary joining. Furthermore, by making the recessed portion 76 the same height as or less than the head height H of the temporary joining means, the temporary joining means does not protrude. Therefore, when joining the frame part 18 to a mating part that is used adjacent to the frame part 18, the head of the temporary joining means does not interfere, and the appearance is also improved. In this context, the head of the temporary joining means is the head 71a in the case of the FDS 71, and the flange 46a in the case of the blind rivet 44. The frame part 18 having this recessed portion 76 does not interfere when joining with a mating part and is a frame part with good appearance quality.

[0068] If the head of the temporary joining means is housed in the concave portion 76, laser welding may be performed from above the temporary joining means, as shown in Figures 28 and 29. Figure 29 is a cross-sectional view of the frame component 18 shown in Figure 28 when cut along a virtual plane C. The virtual plane C shown in Figure 28 is hatched downwards to the left. By performing laser welding across the concave portion 76, the head of the temporary joining means (head 71a of FDS71 in Figure 29) and the plate material 15 melt and mix together, as shown in Figure 29, to form a welded portion 77. By performing laser welding over temporary joining means such as blind rivets 44 and FDS 71 in this way, the concave portion 76 serves as a marker for the laser welding position, and laser welding can be performed at the position where the two plate materials 15 are most tightly joined, thus increasing the reliability of the welding.

[0069] The frame component 18 shown in Figure 30 is formed in the molding process S2 from sheet metal 15 that has been cut to a predetermined length before the molding process S2 is carried out, and clamps 72 are attached to both ends in the longitudinal direction. As shown in Figure 31, the clamps 72 hold the overlapping portions of the sheet metal 15 in the thickness direction, keeping the sheet metal 15 in close contact with each other. The clamps 72 shown in Figure 31 are attached to the third double wall portion 30 where the first vertical wall 33 and the third vertical wall 39 of the frame component 18 overlap, and to the second double wall portion 29 where the second vertical wall 35 and the fourth vertical wall 41 of the frame component 18 overlap.

[0070] The clamp 73 shown in Figure 32 is structured to clamp and fasten one outer end 18a (left end) and the other outer end 18b (right end) of the frame component 18 so that the other end 22 (lower end of the fourth vertical wall 41) of the plate material 15 is sandwiched between them. The temporary joining process using the clamp 73 shown in Figure 32 can be performed even if the plate material 15 has not been cut into individual frame components 18, and it can also be performed even if the plate material 15 has been cut into individual frame components 18. In other words, the temporary joining process using the large clamp 73 shown in Figure 32 can be performed whether the cutting process S1 is performed before the molding process S2, or whether the cutting process S1 is performed after the temporary joining process S3 but before the waiting process S4.

[0071] The temporary joining process performed in temporary joining step S3 can be carried out using blind rivets 44, FDS 71, clamps 72, 73, etc., as described above, but it can also be done using adhesive or brazing, although these are not shown in the figures. The temporary joining process performed in temporary joining step S3 is not limited to the above-mentioned temporary joining means and can be changed as appropriate, as long as at least one of the overlapping plate materials 15 are held in close mechanical or chemical contact to the extent that the shape of the closed cross-sections (first to third closed cross-sections 25 to 27) of the frame component 18 is maintained.

[0072] (A modified version of frame part 18) In the embodiments described above, examples were shown in which a frame component 18 having first to third closed cross-sections 25 to 27 is formed by roll forming. However, as shown in Figures 33 and 34, the present invention is also applicable when a frame component 84 having a long hollow body 83 in which first and second closed cross-sections 81 and 82 are arranged in a continuous line is formed by roll forming. That is, the manufacturing method according to the present invention is a manufacturing method for forming a frame component having a long hollow body in which at least two closed cross-sections are arranged in a continuous line. In Figures 33 and 34, the same or equivalent members as those described in Figures 1 to 32 are denoted by the same reference numerals, and detailed descriptions are omitted as appropriate. In Figures 33 and 34, solid white arrows indicate the position where the main joining process is performed, and dashed white arrows indicate the position where the main joining process can be performed additionally. Also, dashed triangles indicate the position where a temporary joining process is performed.

[0073] The frame component 18 shown in Figure 33 is formed by first forming the first horizontal wall 32, then the first vertical wall 33 and the second horizontal wall 34, and then bending the plate material 15 upward so that it overlaps with one end 21 of the plate material 15 to form the fifth vertical wall 85. After forming the fifth horizontal wall 86 parallel to the first horizontal wall 32, the sixth vertical wall 87 extending downward is formed. The lower end of the sixth vertical wall 87 becomes the other end 24 of the plate material 15. This sixth vertical wall 87 is formed so that it overlaps with the first vertical wall 33. The lower end of the sixth vertical wall 87 becomes the other end 22 of the plate material 15. In this frame component 84, the other end 22 is located outside the closed cross section, and furthermore, the sixth vertical wall 87 is connected to the fifth horizontal wall 86 at one bending point 43, making it prone to warping due to springback. That is, the sixth vertical wall 87 tends to separate from the first vertical wall 33 due to springback, as shown by the dashed line in Figure 33. For this reason, in the frame component 84 shown in Figure 33, a temporary joining process S3 is performed on the fourth double wall section 88 where the sixth vertical wall 87 and the first vertical wall 33 overlap.

[0074] In the frame component 84 shown in Figure 33, of the first double wall portion 28 including one end 21 and the fourth double wall portion 88 including the other end 22, at least the first double wall portion 28 is subjected to the joining process S5. That is, the fourth double wall portion 88 can be subjected to the joining process in addition.

[0075] The frame component 84 shown in Figure 34 is formed such that one end 21 extends downward in the figure relative to the first horizontal wall 32 and overlaps with the second vertical wall 35, and the third vertical wall 39 becomes the other end 22. In this frame component 84, both the one end 21 and the other end 22 are located outside the closed section. The one end 21 and the other end 22 are each connected to the other wall at one bending point 43. For this reason, in the frame component 84 shown in Figure 34, a temporary joining process S3 is performed on the fifth double wall section 89 where the one end 21 overlaps with the second vertical wall 35, and on the sixth double wall section 90 where the other end 22 overlaps with the first vertical wall 33. Furthermore, in the frame component 84 shown in Figure 34, the joining process S5 is performed on at least one of the double wall portions, which is either the fifth double wall portion 89 including one end portion 21 or the sixth double wall portion 90 including the other end portion 22.

[0076] As shown in Figures 33 and 34, even when forming a frame component 84 having only first and second closed cross-sections 81 and 82, it is possible to manufacture a highly rigid frame component having multiple closed cross-sections with high productivity, similar to the embodiments shown in Figures 1 to 32, and to provide a frame component formed by roll forming and a method for manufacturing the same that can suppress springback with a simple method and improve welding accuracy.

[0077] In the embodiments described above, examples were shown in which laser welding is performed in the joining process S5. However, this welding process can be carried out by methods other than laser welding, such as MIG welding or friction stir welding. In the first embodiment described above, the frame component 18 has an outer peripheral frame 36 formed to surround the ladle-shaped portion 31, extending from the tip of the handle of the ladle through the bottom and opening sides of the ladle. However, it may also surround the ladle-shaped portion 31 through the opening and bottom sides of the ladle, and is not limited to an outer peripheral frame 36; it may also have an opening. For example, after forming the ladle-shaped portion 31, the outer frame portion 37 is formed by roll forming in the order of fourth vertical wall 41 → fourth horizontal wall 40 → third vertical wall 39. This outer frame portion 37 is formed in a cup shape with a downward-opening cross-section to accommodate the ladle of the ladle-shaped portion 31, and works in cooperation with the ladle to form two closed cross-sections (first and second closed cross-sections 25, 26). Furthermore, in the first embodiment, the third closed section 27 is provided on the left side of the ladle handle (second vertical wall 35), but it may also be provided on the right side of the ladle handle, and fourth and fifth closed sections (not shown) may be provided above and below or to the left and right. Also, the ladle-shaped portion 31 was roll-formed clockwise, but it may also be roll-formed counterclockwise. [Explanation of Symbols]

[0078] 15...plate material, 18, 84...frame parts, 19...hollow body, 20...rivet driving device, 21...one end, 22...other end, 23...one end, 24...other end, 25...first closed section, 26...second closed section, 27...third closed section, 28...first double wall section, 29...second double wall section, 30...third double wall section, 44...blind rivet, 45...rivet hole, 71...flow drill screw, 72, 73...clamp, 75...flow drill screw driving device, 76...concave shape section, S1...cutting process, S1A, drilling process, S2...forming process, S3...temporary joining process, S4...waiting process, S5...final joining process, S6...concave shape forming process.

Claims

1. A cutting process in which a sheet of metal is cut to a predetermined length, A molding process in which a frame component having a long hollow body with at least two closed cross-sections arranged in a continuous line is formed by applying roll forming to the aforementioned plate material, A temporary joining step is performed on the frame component to maintain the shape of the closed cross-section, A waiting step in which the frame parts after the temporary joining process has been completed are kept in a waiting state, The process includes a main joining step in which the frame components waiting in the aforementioned waiting step are welded, The temporary joining process performed in the temporary joining step is a joining process that holds at least one overlapping plate material together in a state of close mechanical or chemical contact to the extent that the shape of the closed cross-section of the frame component is maintained. In the aforementioned joining process, one end of the initial stage of roll forming of the plate material or the other end of the final stage is continuously welded to the closed section of the plate material along the longitudinal direction of the long hollow body. A method for manufacturing a frame component formed by roll forming, characterized in that, while the frame component is being formed in the molding step, the welding of the main joining step is performed on other frame components in the waiting step.

2. In the method for manufacturing a frame component formed by roll forming as described in claim 1, A method for manufacturing a frame part formed by roll forming, characterized in that the temporary joining process is performed on one end or the other end located outside the closed cross-section while at least the hollow shape of the frame part is maintained.

3. In the method for manufacturing a frame component formed by roll forming as described in claim 2, Furthermore, prior to the molding process, a drilling process is performed to drill rivet holes in the plate material at the locations where the temporary joining process is to be carried out. A method for manufacturing a frame part formed by roll forming, characterized in that the temporary joining step is performed by driving rivets into the rivet holes using a rivet driving device installed downstream of the roll forming apparatus that performs the forming step in the feeding direction of the frame part.

4. In the method for manufacturing a frame component formed by roll forming as described in claim 2, A method for manufacturing a frame component formed by roll forming, characterized in that the temporary joining step is performed by driving a flow drill screw using a flow drill screw driving device installed downstream of the roll forming apparatus that performs the molding step in the feeding direction of the frame component.

5. In the method for manufacturing a frame part formed by roll forming according to claim 3 or claim 4, Furthermore, a concave shaping process is performed either before or during the molding process to form a concave portion in the plate material at the location where the temporary joining process is to be performed. A method for manufacturing a frame part formed by roll forming, characterized in that the temporary joining process in the temporary joining step is performed on the concave portion.

6. In the method for manufacturing a frame component formed by roll forming as described in claim 5, A method for manufacturing a frame part formed by roll forming, characterized in that the depth of the recess in the recessed portion formed in the recessed shape forming step is the same as or deeper than the height of the head of the temporary joining means that performs the temporary joining process.

7. In the method for manufacturing a frame part formed by roll forming according to claim 3 or claim 4, In the aforementioned molding process, the roll forming process is carried out by applying molding stress such that the frame component undergoes compressive deformation. A method for manufacturing a frame part formed by roll forming, characterized in that the temporary joining process in the temporary joining step is performed when the frame part is restored to its normal shape due to springback caused by the forming stress.

8. A frame component formed by roll forming, having a long hollow body in which at least two closed cross-sections are arranged in a continuous line, Multiple contact portions that hold in a state of close mechanical or chemical contact between plate materials, one end on the inside of the closed cross-section and at least one end on the outside of the closed cross-section that overlaps with the other end, The other end has a welded portion that is continuously welded to the closed cross-section along the longitudinal direction of the long hollow body, The plurality of close-fitting portions provided as temporary joints for maintaining the shape of the closed cross-section consist of a plurality of temporary joining means arranged along the longitudinal direction of the long hollow body, thereby forming a portion with a relatively lower joining strength than the welded portion. The frame component formed by roll forming is characterized in that the welded portion, which serves as the joint, is formed between two adjacent close-contact portions of the plurality of close-contact portions.

9. In a frame component formed by roll forming as described in claim 8, A frame component formed by roll forming, characterized in that each of the aforementioned multiple close contact areas is in close contact with one of the following: a rivet, a flow drill screw, an adhesive, or a clamp.

10. In a frame component formed by roll forming as described in claim 9, A frame component formed by roll forming, characterized in that each of the plurality of close contact portions has a concave shape, and the joining means for performing the joining process does not protrude.

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