Manufacturing method of frame component formed by roll forming

Abstract

To provide a manufacturing method of a frame component formed by roll forming that enables manufacturing of a frame component having a plurality of closed cross-sectional parts and having high rigidity, with preferable productivity, and can increase welding accuracy by suppressing spring back with a simple method.SOLUTION: A manufacturing method of a frame component formed by roll forming includes: a cutting step S1 of cutting a plate 5 made of metal; a forming step S2 of forming a frame component having a T-shape junction part 12 having a cross-sectional T-shape and at least two closed cross-sectional parts; a temporary joint step S3; a standby step S4; and a main joint step S5. The cutting step S1 is performed in at least one of before the forming step S2, and after the temporary joint step S3 and before the standby step S4. When the frame component is formed in the forming step S2, main joint is performed on another frame component.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Components 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 arranged continuously in the frame component. Such a frame component is described in, for example, Patent Document 1. The frame component disclosed in Patent Document 1 uses a plurality of plate materials to form the above-described closed cross-sectional portion. That is, this frame component is formed by a first plate material having a formed portion with an S-shaped cross-section and second and third plate materials welded to both sides of the first plate material.

[0003] On the other hand, as a frame component having a plurality of frames with a square cross-section, there is, for example, one described in Patent Document 2. The frame component disclosed in 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 butted against each other at the lowermost part of the B shape and are welded by high-frequency welding. Further, the intermediate portion in the vertical direction of the B shape is formed so as to be a concave portion that is released toward the left side of the B shape. The bottom portions of this concave portion are overlapped with each other and spot welding is performed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The frame parts disclosed in Patent Document 1 had a problem in that when forming a closed cross-sectional portion in which multiple adjacent rectangular cross-sectional frames are lined up in succession, such as a closed cross-sectional portion with a cross-section shaped like a character "H" or "E", the number of manufacturing steps, such as positioning and welding of multiple plate materials, was large, resulting in low productivity. The frame part disclosed in Patent Document 2 has a recess formed in the vertical middle part of the B shape, so that the rigidity is insufficient and it cannot be used as a frame for accommodating an automobile battery.

[0006] Furthermore, when welding one end and the other end of the plate material of the frame part shown in Patent Document 2 by high-frequency welding, a jig may be required to prevent the one end and the other end from separating due to springback and to improve welding accuracy. One possible jig is a box-shaped welding jig that holds the frame part from both the left and right sides in a B shape. For this reason, when manufacturing frame parts by roll forming, there is a demand for a simple method to suppress springback and improve welding accuracy.

[0007] An object of the present invention is to provide a method for manufacturing frame parts formed by roll forming, which can produce highly rigid frame parts having multiple closed cross-sectional portions with high productivity, and which can suppress springback in a simple manner to improve welding accuracy. [Means for solving the problem]

[0008] To achieve this object, a method for manufacturing a frame component formed by roll forming according to the present invention includes a cutting step of cutting a metal plate material to a predetermined length, a forming step of performing roll forming on the plate material so as to surround one end of the plate material to form a frame component having a T-shaped joint portion with a T-shaped cross section where one end abuts, and at least two closed cross-sectional portions including two closed cross-sectional portions sandwiching the T-shaped joint portion, a temporary joining step of performing a temporary joining process on the frame component to hold the shape, a waiting step of waiting for the frame component after the temporary joining process is completed, and a main joining step of continuously welding the frame component waiting in the waiting step. The cutting step is performed either before the forming step and after the temporary joining step and before the waiting step. When the frame component is being formed in the forming step, the main joining is performed on another frame component.

[0009] The present invention relates to a method for manufacturing a frame component formed by roll forming. The frame component has a ladle-shaped portion formed in a ladle-shaped cross section with one end located at the open end of the ladle, and an outer frame portion formed in a cup-shaped cross section for accommodating the ladle and forming two closed cross-sectional portions that sandwich the T-shaped joint portion in cooperation with the ladle. The temporary joining step may be performed by performing the temporary joining process at least on a portion where the outer frame portion overlaps the bottom of the ladle and a portion where the outer frame portion overlaps the handle of the ladle.

[0010] The present invention relates to a method for manufacturing a frame component formed by roll forming. Further, a drilling step of drilling rivet holes at positions on the plate material where the temporary joining process is to be performed before the forming step is carried out. The temporary joining step may be performed by driving rivets into the rivet holes using a rivet driving device installed on the downstream side in the feeding direction of the frame component from the roll forming device for performing the forming step.

[0011] In the method for manufacturing a frame component formed by roll forming, in the roll forming in the forming step, forming stress is applied so that the frame component is compressed and deformed, and the temporary joining process in the temporary joining step may be performed when the frame component is restored to a normal shape due to springback caused by the forming stress.

[0012] In the method for manufacturing a frame component formed by roll forming, before roll forming is performed on the plate material in the forming step, a groove forming step of forming a groove into which one end is fitted is performed on the plate material, and in the forming step, the T-shaped joint may be formed into a final shape by fitting one end into the groove.

[0013] In the method for manufacturing a frame component formed by roll forming, before roll forming is performed on the plate material in the forming step, a step forming step of forming a step portion so that a part of the plate material is biased in one direction in the thickness direction is performed, and in the roll forming step, the T-shaped joint may be formed into a final shape by engaging one end with the step portion.

[0014] In the method for manufacturing a frame component formed by roll forming, the temporary joining process in the temporary joining step may be performed in a state where the T-shaped joint is formed into the final shape.

[0015] In the method for manufacturing a frame component formed by roll forming, the main joining step may be performed by welding the T-shaped joint from the outside of the frame component by laser welding.

[0016] In the method for manufacturing a frame component formed by roll forming, the laser welding may also be performed at a position adjacent to the rivet driven by the riveting device in the temporary joining step in the longitudinal direction of the frame component.

[0017] In the method for manufacturing a frame component formed by roll forming according to the present invention, the cutting step is performed before the forming step is performed, and the temporary joining process performed in the temporary joining step may be performed by clamping, with a clamp, a portion where the plate materials are overlapped at both end portions in the longitudinal direction of the frame component.

[0018] In the method for manufacturing a frame component formed by roll forming according to the present invention, the temporary joining process performed in the temporary joining step may be performed by sandwiching and tightening, with a clamping member, one outer end portion and the other outer end portion of the frame component such that the other end portion of the plate material is sandwiched therebetween.

Advantages of the Invention

[0019] According to the present invention, it is possible to provide a method for manufacturing a frame component formed by roll forming, which can produce a highly rigid frame component having a plurality of closed cross-sectional portions with high productivity, and can suppress springback by a simple method to improve welding accuracy.

Brief Description of the Drawings

[0020]

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MODE FOR CARRYING OUT THE INVENTION

[0021] (First Embodiment) Hereinafter, a method of manufacturing a frame component formed by roll forming according to the present invention will be described in detail with reference to FIGS. 1 to 23. (Outline Explanation of Method of Manufacturing Frame Component) The method of manufacturing a frame component formed by roll forming according to this embodiment is a method in which a cutting step S1, a forming step S2, a temporary joining step S3, a standby step S4, and a main joining step S5 are carried out in this order, as shown in the flowchart of FIG. 1. The frame component manufactured by this manufacturing method can be used as a component for supporting in-vehicle components such as an automobile (not shown) or a component constituting a part of the vehicle body skeleton.

[0022] The cutting process S1, the forming process S2, and the temporary joining process S3 are carried out by the roll forming machine 1 shown in FIG. 2. The standby process S4 is carried out at the storage location 2 (see FIG. 3), and the main joining process S5 is carried out by the main welding machine 3 (see FIG. 3). The roll forming machine 1 feeds the metal plate 5 from the cutting device 4 located on the far left in FIG. 2 to the right side in FIG. 1 to manufacture a product of a predetermined shape. The cutting device 4 is a device for carrying out the cutting process S1. This cutting device 4 has functions of cutting a metal plate 5 having a predetermined width to a predetermined length, performing punching, grooving, pressing, etc. on the plate 5, and feeding the plate 5 to the downstream side in the feeding direction.

[0023] A multi-stage roll forming machine 6 is arranged on the downstream side in the feeding direction of the plate 5 from the cutting device 4, and a temporary joining device 7 is arranged on the downstream side in the feeding direction of the plate 5 from the multi-stage roll forming machine 6. The multi-stage roll forming machine 6 is a device for carrying out the forming process S2. In this embodiment, the multi-stage roll forming machine 6 corresponds to the "roll forming device" referred to in the present invention. This multi-stage roll forming machine 6 uses a number of rolls 6a to bend the plate 5 into a predetermined shape by roll forming to form the frame part 8 shown in FIGS. 4 and 5. FIG. 4 shows a cross-sectional view when the frame part 8 is cut along the virtual plane A shown in FIG. 5. The virtual plane A shown in FIG. 5 is hatched diagonally downward to the left. The description of roll forming will be given later.

[0024] The temporary joining device 7 is a device for carrying out the temporary joining process S3. This temporary joining device 7 performs a temporary joining process in which the shape is held on the frame part 8 formed by the multi-stage roll forming machine 6. The temporary joining device 7 according to this embodiment is constituted by a rivet driving device 9. The temporary joining process according to this embodiment is a rivet joining of the overlapping portions of the plates 5. A detailed description of the temporary joining process will be given later.

[0025] After the temporary joining process by the temporary joining device 7 is completed, the frame part 8 is taken out from the roll forming machine 1 and transferred to the storage location 2. The multi-stage roll forming machine 6 continuously creates the frame part 8 after the temporary joining process is completed. For this reason, as shown in FIG. 3, a plurality of frame parts 8 are stored in the storage location 2 in order to wait for the process by the main joining process S5, which is the next process. In this way, the process in which the frame part 8 waits for the next process at the storage location 2 becomes the waiting process S4. In the main joining process S5, the frame part 8 waiting at the storage location 2 is supplied to the main welding machine 3, and main joining is performed to restrict the shape change of the frame part 8. In the main joining process S5 according to this embodiment, laser welding is performed. A detailed description of the laser welding will be given later.

[0026] (Specific description of the method for manufacturing the frame part) (Description of the forming process S2) The frame part 8 shown in FIG. 4 is formed by performing roll forming on the plate material 5 so as to surround one end 11 of the plate material 5. By performing roll forming in this way, a T-shaped joint portion 12 having a T-shaped cross section with one end 11 of the plate material 5 abutted is formed. The T-shaped joint portion 12 will be subjected to laser welding in the main joining process S5, although details will be described later. In addition, when explaining each part of the frame part 8, for convenience, the upper side of FIG. 4 is regarded as the upper part of the frame part 8, and the left side of FIG. 4 is regarded as the left side part of the frame part 8.

[0027] The roll forming according to this embodiment is performed so that a first closing surface portion 13 and a second closing surface portion 14 sandwiching the T-shaped joint portion 12 and a third closing surface portion 15 located below the frame part 8 shown in FIG. 4 are formed. When forming the first to third closing surface portions 13 to 15, first, a ladle-shaped portion 16 having a ladle-shaped cross section including one end 11 of the plate material 5 is formed at the initial stage of roll forming. The ladle-shaped portion 16 has one end 11 of the plate material 5, and includes a first transverse wall 21 extending leftward in FIG. 4 from the one end 11, a first longitudinal wall 22 extending downward from the left end of the first transverse wall 21, a second transverse wall 23 extending rightward from the lower end of the first longitudinal wall 22, and a second longitudinal wall 24 extending downward from the right end of the second transverse wall 23. The ladle-shaped portion 16 is formed such that one end 11 of the plate material 5 is located at the open end of the ladle, the first longitudinal wall 22 serves as the bottom of the ladle, and the second longitudinal wall 24 serves as the handle of the ladle.

[0028] Since the frame component 8 according to this embodiment has three closed cross-sectional portions (the first to third closed cross-sectional portions 13 to 15), after forming the ladle-shaped portion 16, the outer peripheral frame 17 is formed so as to cooperate with the ladle-shaped portion 16 to form the first to third closed cross-sectional portions 13 to 15. The outer peripheral frame 17 includes an outer frame portion 18 having a cross-sectional cup shape for accommodating the ladle of the ladle-shaped portion 16. The outer frame portion 18 is a portion that cooperates with the ladle of the ladle-shaped portion 16 to form two closed cross-sectional portions (the first and second closed cross-sectional portions 13, 14) sandwiching the T-shaped joint portion.

[0029] The outer peripheral frame 17 is formed so as to surround the ladle-shaped portion 16 from the bottom side and the open side of the ladle via the lower end (the tip of the handle of the ladle) of the second longitudinal wall 24. More specifically, the outer peripheral frame 17 includes a third transverse wall 25 extending leftward from the lower end of the second longitudinal wall 24, a third longitudinal wall 26 extending upward from the left end of the third transverse wall 25 and overlapping the first longitudinal wall 22, a fourth transverse wall 27 extending rightward from the upper end of the third longitudinal wall 26, and a fourth longitudinal wall 28 extending downward from the right end of the fourth transverse wall 27 and overlapping one end 11 of the plate material 5 and the second longitudinal wall 24. The outer frame portion 18 is composed of the third longitudinal wall 26, the fourth transverse wall 27, and the fourth longitudinal wall 28.

[0030] When forming the frame part 8 shown in Fig. 4 by the roll forming method, the forming sequence is as shown in, for example, Figs. 6(A) to (G), 7(A) to (D), and 8(A) to (D). The roll forming is performed by the multi-stage roll forming machine 6 of the roll forming machine 1 shown in Fig. 1. Figs. 6(A) to (G), 7(A) to (D), and 8(A) to (D) are cross-sectional views seen from the longitudinal direction of the plate material 5.

[0031] In order to form the frame part 8, first, as shown in Figs. 6(A) to 7(B), the ladle-shaped part 16 is formed. That is, the first transverse wall 21 including one end 11 of the plate material 5 in a flat state is bent, and the first longitudinal wall 22, the second transverse wall 23, and the second longitudinal wall 24 are formed in this order. The radius of curvature of the curved part 29 (see Fig. 4) between each wall can be adjusted by the multi-stage roll forming machine 6 according to the rigidity and collision performance. Then, as shown in Figs. 7(C) to 8(D), the third transverse wall 25, the third longitudinal wall 26, the fourth transverse wall 27, and the fourth longitudinal wall 28 are formed in this order.

[0032] Specifically, in the process shown in Fig. 7(D), the third longitudinal wall 26 and the first longitudinal wall 22 are overlapped so as to form a double wall. Then, in the processes shown in Figs. 8(A) to (B), the third longitudinal wall 26 is bent while forming the curved part 29 to form the fourth transverse wall 27. After that, in the processes shown in Figs. 8(C) to (D), the fourth longitudinal wall 28 is overlapped with one end 11 of the plate material 5 and the second longitudinal wall 24 to form the T-shaped joint part 12. After overlapping the third longitudinal wall 26 with the first longitudinal wall 22 in the process shown in Fig. 7(D), as shown in Fig. 7(E), the third longitudinal wall 26 can be bent to the left in the drawing to form a frame 17a with a square cross-section at the upper part on the left side of the outer peripheral frame 17 in the drawing.

[0033] This frame 17a with a square cross-section is formed by bending the third longitudinal wall 26 clockwise in the drawing, and finally formed so as to overlap with the portion bent to the left above in a state where the third longitudinal wall 26 extends downward, and a closed cross-section is added to the outside. After forming the frame 17a with a square cross-section in this way, the third longitudinal wall 26 is bent so that the tip points to the right in the drawing to obtain the state shown in Fig. 8(B). When roll forming is performed in this way, springback occurs in the bent portion 29, and the frame component 8 may be deformed as shown in FIG. 9 after forming. When springback occurs, the fourth vertical wall 28 moves away from one end 11 of the plate material 5 and the second vertical wall 24, and the first vertical wall 22 moves away from the third vertical wall 26. When deformed in this way, laser welding cannot be performed at the T-shaped joint 12 in the subsequent process. In order to prevent deformation due to such springback, a temporary joining process S3 is carried out after the forming process S2.

[0034] (Description of the temporary joining process S3) The temporary joining process S3 is carried out by performing a temporary joining process on at least a first overlapping portion 31 (see FIG. 4) where the outer frame portion 18 (the third vertical wall 26) overlaps the bottom of the handle of the handle ladle shape (the first vertical wall 22) in the handle ladle portion 16 and a second overlapping portion 32 where the outer frame portion 18 (the fourth vertical wall 28) overlaps the handle of the handle ladle (the second vertical wall 24). In this embodiment, the temporary joining process S3 is carried out using a rivet driving device 9 installed on the downstream side in the feeding direction of the frame component 8 from the multi-stage roll forming machine 6 that performs the forming process S2.

[0035] As shown in FIG. 10, the rivet driving device 9 performs rivet joining using a blind rivet 33. FIG. 10 is a cross-sectional view when the frame component 8 shown in FIG. 5 is cut by a virtual plane B. The virtual plane B shown in FIG. 5 is hatched diagonally downward to the right. Rivet joining is performed by inserting the blind rivet 33 into the rivet hole 34 of the frame component 8 from the outside of the frame component 8. The rivet hole 34 can be drilled at a predetermined position of the plate material 5 by the cutting device 4. That is, as shown in FIG. 11, the cutting process S1 according to this embodiment is carried out including a drilling process S1A for drilling the rivet hole 34.

[0036] The rivet hole 34 is composed of an outer rivet hole 34a formed in the outer frame portion 18 (the third and fourth vertical walls 26, 28) of the frame component 8 and an inner rivet hole 34b formed in the first and second vertical walls 22, 24. The aperture diameter of the outer rivet hole 34a is larger than that of the inner rivet hole 34b. As shown in FIGS. 12(A) to (C), the blind rivet 33 is composed of a cylindrical main body portion 35 and a shaft portion 36 movably inserted into the main body portion 35. A flange 35a is provided at one end of the main body portion 35. The shaft portion 36 penetrates the main body portion 35. At the end of the shaft portion 36 protruding on the side opposite to the flange 35a of the main body portion 35, a head 36a having an outer diameter equivalent to the outer diameter of the main body portion 35 is provided.

[0037] In order to perform the temporary joining process S3 using this blind rivet 33, first, as shown in FIG. 12(A), the blind rivet 33 is inserted into the rivet hole 34 from the outside of the frame component 8, and the shaft portion 36 is pulled toward the outside of the frame component 8 with the flange 35a pressed against the third and fourth vertical walls 26, 28. By pulling the shaft portion 36 in this way, the tip 35b of the main body portion 35 is expanded by the head 36a as shown in FIG. 12(B). Then, the shaft portion 36 is further pulled by a predetermined length, and the shaft portion 36 is cut at the portion protruding from the flange 35a in a state where the tip 35b of the main body portion 35 is greatly deformed as shown in FIG. 12(C). By performing the temporary joining process in this way, deformation due to springback thereafter is restricted, and one end 11 of the plate material 5 is held in contact with the fourth vertical wall 28 at the T-shaped joint portion 12.

[0038] Springback starts when the forming by the multi-stage roll forming machine 6 is completed. For this reason, the outer rivet hole 34a and the inner rivet hole 34b may be displaced due to the springback that occurs before the temporary joining process is carried out. Since the outer rivet hole 34a according to this embodiment is formed such that the hole diameter is larger than that of the inner rivet hole 34b, a wider tolerance range can be taken with respect to the displacement due to springback.

[0039] In order to prevent the outer rivet hole 34a from being displaced with respect to the inner rivet hole 34b due to the springback that occurs before the temporary joining process is carried out, it is conceivable to apply a forming stress so that the roll form forming compresses and deforms the frame part 8 from its normal shape. That is, when forming the outer peripheral frame 17 of the frame part 8, a part of the frame part 8 is elastically deformed as shown in FIG. 13, and the forming is performed so as to become the normal shape in the process of springback due to stress release after forming. The frame part 8 shown in FIG. 13 is deformed such that the first and second horizontal walls 21, 23 of the handle ladle-shaped part 16 are inclined downward to the right, and the lower part of the frame part 8 is crushed in the left-right direction by compression. FIG. 13 is drawn with the frame part 8 deformed larger than the actual one for easy understanding of the deformation.

[0040] By performing roll form forming in consideration of stress release after forming in this way, the frame part 8 is restored to its normal shape, that is, the shape shown in FIG. 4, due to springback caused by stress release after forming. When the frame part 8 is compressed and deformed by roll form forming, immediately after forming, the outer rivet hole 34a and the inner rivet hole 34b are displaced as shown in FIG. 14(A). However, when the frame part 8 is restored to its normal shape due to springback, the displacement between the outer rivet hole 34a and the inner rivet hole 34b is eliminated as shown in FIG. 14(B). By performing the temporary joining process at this time, the rivet joining by the blind rivet 33 is correctly carried out.

[0041] In order to perform rivet joining in this manner, the temporary joining device 7 may be arranged so that the frame part 8 is restored to its normal shape while being sent from the multi-stage roll forming machine 6 to the temporary joining device 7. In order to achieve this, it is conceivable that the distance D (see Fig. 2) between the multi-stage roll forming machine 6 and the temporary joining device 7 is set to the distance that the frame part 8 moves until it is restored to its normal shape after forming. By adopting this configuration, when the frame part 8 that has been compression-deformed by roll forming is restored to its normal shape due to springback caused by stress relaxation, the temporary joining process is carried out.

[0042] When the frame part 8 is compression-deformed by roll forming, in order to ensure that one end 11 of the plate material 5 always abuts against the fourth vertical wall 28 at the T-shaped joint 12 during the process of the frame part 8 restoring, it is conceivable to adopt the configuration shown in Figs. 15 and 16. The T-shaped joint 12 shown in Fig. 15 has a structure in which one end 11 of the plate material 5 is fitted into a groove 37 formed in the fourth vertical wall 28. The groove 37 shown in Fig. 15 is formed by a guiding shape part 38 continuous with the inner side surface 28a of the fourth vertical wall 28 and a groove bottom part 39 connected to the guiding shape part 38. The guiding shape part 38 is formed by an inclined surface extending from the side surface 28a into the groove 37. The inclined surface is inclined so that the opening width of the groove 37 gradually widens as it goes out of the groove 37. The groove bottom part 39 is composed of a side surface 39a extending in the depth direction of the groove 37 and a bottom surface 39b serving as the groove bottom, and is formed so as to be a C-shaped groove with a square cross-section. The groove width of the groove bottom part 39 is the width into which one end 11 of the plate material 5 is fitted.

[0043] The groove 37 shown in Fig. 15 can be formed by cutting or forming. The groove forming process of forming the groove 37 in the fourth vertical wall 28 by cutting or forming is carried out before roll forming is performed on the plate material 5 in the forming process S2. For example, as shown in Fig. 17, the groove forming process S6 can be carried out between the cutting process S1 and the forming process S2. When forming the groove 37 by cutting, it is carried out by pressing the rotating cutting tool 41 against the plate material 5 as shown in Fig. 18(A). The cutting tool 41 can be provided in the cutting device 4, or can also be arranged between the cutting device 4 and the multi-stage roll forming machine 6.

[0044] When forming the groove 37 by shaping, it is carried out by pressing the groove-forming roll 42 against the plate material 5 as shown in Fig. 18(B). The groove-forming roll 42 can be provided at a position before the roll forming of the multi-stage roll forming machine 6 is carried out. A groove processing part 43 is provided on the outer peripheral part of the roll 42. By pressing and rotating this roll 42 against the plate material 5, the shape of the groove processing part 43 is transferred to the plate material 5 and the groove 37 is formed. Note that the groove 37 is formed in a shape in which a part of the inner surface (side surface 28a) of the fourth vertical wall 28 is recessed, but a convex shape may be exposed on the outer surface of the part where this recess is formed. When the convex shape is exposed in this way, it becomes a mark for laser welding.

[0045] In the T-shaped joint 12 shown in Fig. 15, in the process of the fourth vertical wall 28 approaching one end 11 of the plate material 5 by roll forming, as shown in Fig. 19, immediately after the corner part 44 of the one end 11 passes through the guide-shaped part 38, it fits into the corner part 45 of the groove bottom 39. Then, with this corner part 45 as the center, the fourth vertical wall 28 tilts clockwise in the drawing, and one end 11 of the plate material 5 fits into the groove bottom 39. By fitting one end 11 of the plate material 5 into the groove 37 in this way, the T-shaped joint 12 of the final shape is formed.

[0046] The T-shaped joint 12 shown in Fig. 16 has a structure in which one end 11 of the plate material 5 engages with a stepped part 46 formed on the fourth vertical wall 28. The stepped part 46 is formed on the fourth vertical wall 28 such that a part of it is offset in one direction in the thickness direction. The stepped part 46 shown in Fig. 16 is formed such that the part of the fourth vertical wall 28 located above one end 11 of the plate material 5 is offset to the left. This stepped part 46 can be formed by press forming using the press function of the cutting device 4.

[0047] The step forming process of forming the step portion 46 on the fourth vertical wall 28 is carried out before roll forming is performed on the plate material 5 in the forming process S2. For example, as shown in FIG. 20, the step forming process S7 can be carried out between the cutting process S1 and the forming process S2. When one end 11 of the plate material 5 engages with the step portion 46 formed on the fourth vertical wall 28, the T-shaped joint portion 12 of the final shape is formed.

[0048] (Description of this joining process S5) This joining process S5 is carried out by sequentially feeding the frame parts 8 that have been subjected to temporary joining treatment and transferred to the storage location 2 into the main welding machine 3. That is, in this joining process S5, when the frame parts 8 are being formed in the forming process S2, laser welding is performed on the other frame parts 8 (the other frame parts 8 in the standby process S4) that are waiting in the standby process S4. The laser welding is consistently carried out by the same welding for the frame parts 8 waiting in the standby process S4. In this joining process S5, it is desirable to perform laser welding on a plurality of frame parts 8 simultaneously using a plurality of main welding machines 3. The reason for this is that the joining (laser welding) that regulates the cross-sectional shape of the frame part provided with two closed cross-sections on both sides of the T-shaped joint portion requires a longer working time compared to roll forming, and the productivity can be increased by performing laser welding on a plurality of frame parts 8 simultaneously. As shown in FIG. 21, the laser welding is carried out by irradiating laser light L from the outside of the frame part 8 (from the side opposite to the first horizontal wall 21) to the T-shaped joint portion 12. FIG. 21 shows the T-shaped joint portion 12 when the groove 37 is used, but the same applies even when the groove 37 is not used.

[0049] The laser beam L is irradiated onto the outer surface 28b of the fourth vertical wall 28 at a position corresponding to the first horizontal wall 21 (one end 11 of the plate material 5). By irradiating the laser beam L onto the T-shaped joint portion 12 in this way, a part of the fourth vertical wall 28 and a part of the first horizontal wall 21 are melted and mixed together, and these are welded. By performing laser welding, a penetration portion 47 having a bullet head shape shown with hatching slanting downward to the left in FIG. 21 is generated. The bullet head shape of the penetration portion 47 is a convex shape extending from the laser irradiation surface (outer surface 28b) toward the first horizontal wall 21. Due to the bullet head-shaped penetration portion, the first horizontal wall 21 becomes more likely to fall with respect to the load from the laser irradiation direction. When the first horizontal wall 21 falls, the load is likely to concentrate on the curved portion 29, and the impact absorption amount increases.

[0050] As shown by reference numeral 48 for the welded portion in FIG. 22, laser welding is continuously performed from one end portion in the longitudinal direction to the other end portion of the frame component 8. When this joining step S5 is completed, the frame component 51 having the final shape with the shape change regulated is completed. Note that laser welding can also be performed at a position adjacent to the longitudinal direction of the blind rivet 33 driven by the riveting device 9 in the temporary joining step S3, as shown in FIG. 23. In the frame component 8 shown in FIG. 23, laser welding is performed so that the welded portions 52 are formed linearly between a plurality of temporary joining processing portions (blind rivets 33) arranged at predetermined intervals in the longitudinal direction.

[0051] (Explanation of the effects according to the first embodiment) The manufacturing method of the frame part formed by roll forming according to this embodiment includes a cutting step S1 of cutting a metal plate material 5 into a predetermined length, a forming step S2 of performing roll forming on the plate material 5 to form a frame part 8 having a T-shaped joint part 12 with a T-shaped cross section and first, second, and third closed cross-sectional parts 13, 14, and 15 sandwiching the T-shaped joint part 12, a temporary joint step S3 of performing a temporary joint process in which the shape of the frame part 8 is held, a standby step S4 of waiting for the frame part 8, and a main joint step S5 of continuously performing main welding on the frame part 8 waiting in the standby step S4. When the frame part 8 is being formed in the forming step S2, main welding is performed on another frame part 8 in the standby step S4.

[0052] According to this manufacturing method, since a plurality of closed cross sections (first and second closed cross-sectional parts 13, 14) adjacent to each other so as to sandwich the T-shaped joint part 12 can be formed, a frame part 51 with high rigidity can be manufactured. This frame part 51 can be used as a side frame of a battery case for accommodating an electric vehicle battery. Since the temporary joint process is performed after roll forming, even if the standby step S4 is carried out after roll forming, the frame part 8 will not be deformed by springback. For this reason, the main welding accuracy after roll forming can be improved by a simple method without using a box-type welding jig or the like.

[0053] Since the joining (laser welding) time for regulating the cross-sectional shape of the frame part with two closed cross sections provided on both sides of the T-shaped joint part is longer than the time required for roll forming, by providing the standby step S4, production can be achieved without reducing the roll forming speed, and productivity can be improved. Therefore, according to this embodiment, it is possible to provide a manufacturing method of a frame part formed by roll forming that can produce a frame part with high rigidity having a plurality of closed cross-sectional parts with high productivity, and can suppress springback by a simple method and improve welding accuracy.

[0054] The frame part 8 formed by the manufacturing method of the frame part according to this embodiment has a ladle-shaped part 16 formed in a cross-sectional ladle shape with one end 11 of the plate material 5 located at the open end of the ladle, and an outer frame part 18 formed in a cross-sectional cup shape for accommodating the ladle and forming two blocking parts (the first and second blocking parts 13, 14) that cooperate with the ladle to sandwich the T-shaped joint part. The temporary joining step S3 is carried out by performing a temporary joining process at least on a part where the outer frame part 18 overlaps the bottom of the ladle and a part where the outer frame part 18 overlaps the handle of the ladle.

[0055] In this embodiment, a punching step S1A of drilling a rivet hole 34 is carried out at a position on the plate material 5 where the temporary joining process is to be performed before the forming step S2. The temporary joining step S3 is carried out by driving a blind rivet 33 into the rivet hole 34 using a rivet driving device 9 installed on the downstream side in the feeding direction of the frame part 8 from the multi-stage roll forming machine 6 that performs the forming step S2. Since roll forming can form a complex closed cross-section, a complex closed cross-section including the T-shaped joint part 12 can be easily made. However, parts that cannot be over-bent are in a state of compressive deformation of the cross-section, so they will return due to springback. Therefore, that part is temporarily joined by a temporary joining process. That is, the bending points around the T-shaped joint part 12 (the connection part between the second vertical wall 24 and the third horizontal wall 25, the connection part between the fourth horizontal wall 27 and the fourth vertical wall 28) may be in a state where the opening is larger than the normal position due to springback because they cannot be over-bent after forming the T-shaped joint part 12. Therefore, by configuring the opening of the ladle to be the T-shaped joint part 12 and performing a temporary joining process on the part that becomes the bottom of the ladle and the part that becomes the handle, springback can be suppressed. A complex closed cross-section including the T-shaped joint part 12 cannot be temporarily joined by spot welding, but one-sided joining can be achieved by using rivets. Also, even when the temporary joining process is performed on both sides of the frame part 8, the rivet driving device 9 can drive rivets from both sides of the frame part 8, so the time required for the temporary joining process can be short. By performing temporary joining on both sides of the frame part 8, the strength of the temporary joining is stabilized.

[0056] In the roll forming in the forming step S2 according to this embodiment, it is conceivable to apply a forming stress so that the frame component 8 is compression-deformed. The temporary joining process in the temporary joining step S3 is carried out when the frame component 8 is restored to its normal shape due to springback caused by stress release. According to this embodiment, since laser welding can be performed on the frame component 8 having a normal shape in the main joining step S5, a high-quality frame component can be manufactured.

[0057] In this embodiment, a groove 37 into which one end 11 of the plate material 5 is fitted is formed in the plate material 5. When the one end 11 of the plate material 5 is fitted into the groove 37 in the forming step S2, it is possible to prevent the T-shaped joint portion 12 from not being joined due to springback. Also, fitting can be performed while performing roll forming within a closed cross-section.

[0058] In this embodiment, a stepped portion 46 is formed in the plate material 5 so that a part of it is offset in one direction in the thickness direction. When the one end 11 of the plate material 5 is engaged with the stepped portion 46 in the forming step S2, it is possible to prevent the T-shaped joint portion 12 from not being joined due to springback. Also, engagement can be performed while performing roll forming within a closed cross-section.

[0059] In this embodiment, the temporary joining process in the temporary joining step S3 is carried out in a state where the T-shaped joint portion 12 is formed in its final shape. Therefore, the product shape of the closed cross-section adjacent to the T-shaped joint portion 12 can be maintained.

[0060] The main joining step S5 according to this embodiment is carried out by laser-welding the T-shaped joint portion 12 from the outside of the frame component 8. The T-shaped joint portion 12 is inside the closed cross-section, but with laser welding, welding can be performed from one side of the frame component 8. Therefore, a highly rigid frame component can be manufactured.

[0061] In this embodiment, when laser welding is also performed at a position adjacent to the longitudinal direction of the rivet and the frame part 8, it is possible to surely prevent the shape of the final product from changing.

[0062] (Second Embodiment) The cutting process S1 can be performed after the forming process S2. An embodiment in the case of adopting this configuration will be described with reference to FIGS. 24 and 25. In FIGS. 24 and 25, members that are the same as or equivalent to those described with reference to FIGS. 1 to 23 are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0063] The manufacturing method of the frame part formed by roll forming in the case of adopting this embodiment is carried out as shown in the flowchart of FIG. 25 by using the roll forming machine 61 shown in FIG. 24. The roll forming machine 61 feeds the metal plate material 5 to the right side in FIG. 24 from the uncoiler 62 located at the leftmost position in FIG. 24 to manufacture a product having a predetermined shape. The metal plate material 5 is mounted on the uncoiler 62 in a coiled state.

[0064] Downstream of the uncoiler 62 in the feeding direction of the plate material 5, devices such as a pre-hole press 63, a multi-stage roll forming machine 64, a temporary joining device 65, and a cutting machine 66 are arranged side by side in this order. The pre-hole press 63 performs machining such as drilling, cutting, and pressing on the plate material 5. The rivet hole 34, the groove 37, the stepped portion 46, etc. can be formed by this pre-hole press 63.

[0065] The cutting machine 66 cuts the plate material 5 formed in a cylindrical shape to a predetermined length after the temporary joining process. When the plate material 5 is cut by the cutting machine 66, the frame part 8 that becomes the frame part 51 is formed. The frame part 8 is sent to the storage place 2 shown in FIG. 3 and sequentially fed into the main welding machine 3. When adopting this configuration, as shown in Fig. 23, after the forming process S2 and the temporary joining process S3 are completed, the cutting process S1 is carried out, and then the standby process S4 and the main joining process S5 are sequentially carried out. That is, the cutting process S1 is carried out either after the temporary joining process S3 and before the standby process S4 as shown in this embodiment, or before the forming process S2 as in the above-described embodiment. By carrying out the cutting process S1 after the temporary joining process S3, the plate material 5 formed in a cylindrical shape can be cut in a state where deformation due to springback is suppressed.

[0066] (Other embodiments of the temporary joining process) In the case of adopting the first embodiment, the temporary joining process is carried out by the blind rivet 33. However, the temporary joining process can be carried out by the clamps 71 and 72 as shown in Figs. 26 to 28. In Figs. 26 to 28, members that are the same as or equivalent to those described with reference to Figs. 1 to 23 are denoted by the same reference numerals, and detailed descriptions thereof are appropriately omitted.

[0067] The frame component 8 shown in Fig. 26 is formed by forming the plate material 5 cut to a predetermined length before the forming process S2 is carried out, and the clamps 71 are respectively attached to both longitudinal ends. As shown in Fig. 27, the clamp 71 clamps the portion where the plate materials 5 overlap in the thickness direction and holds the plate materials 5 in a state of being in close contact with each other. The clamp 71 shown in Fig. 27 is attached to the portion where the first longitudinal wall 22 and the third longitudinal wall 26 of the frame component 8 overlap and the portion where the second longitudinal wall 24 and the fourth longitudinal wall 28 of the frame component 8 overlap, respectively.

[0068] The clamp 72 shown in Fig. 28 corresponds to the "clamping member" referred to in the present invention, and has a structure in which the other end portion 73 (the lower end portion of the fourth vertical wall 28) of the plate material 5 sandwiches and tightly binds one outer end portion 8a (the left end portion) and the other outer end portion 8b (the right end portion) of the frame part 8. The temporary joining process by the clamp 72 shown in Fig. 28 can be carried out even when the plate material 5 has not been cut into individual frame parts 8, and can also be carried out after the plate material 5 has been cut into individual frame parts 8. That is, the temporary joining process by the large clamp 72 shown in Fig. 28 can be carried out regardless of whether the cutting step S1 is carried out before the forming step S2 or the cutting step S1 is carried out after the temporary joining step S3 and before the standby step S4.

[0069] (Modification example of frame part 8) In each of the above-described embodiments, an example in which the frame part 8 having the first to third closing surface parts 13 to 15 is formed by roll forming has been shown. However, as shown in Figs. 29 to 31, the present invention is also applicable to the case where the frame part 83 having only the first and second closing surface parts 81 and 82 located on both sides of the T-shaped joint part 12 is formed by roll forming. In Figs. 29 to 31, members that are the same as or equivalent to those described with reference to Figs. 1 to 23 are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.

[0070] The frame part 83 shown in Figs. 29 to 31 forms the first vertical wall 22 and the second horizontal wall 23 from the first horizontal wall 21, and then bends the plate material 5 upward so as to overlap the tip of the first horizontal wall 21 (one end 11 of the plate material 5) to form the fifth vertical wall 84. Then, after forming the fifth horizontal wall 85 parallel to the first horizontal wall 21, the sixth vertical wall 86 extending downward is formed. The lower end of the sixth vertical wall 86 becomes the other end of the plate material 5. The sixth vertical wall 86 is formed so as to overlap the first vertical wall 22. In this embodiment, a temporary joining process is performed on the overlapping portion 87 where the first vertical wall 22 and the sixth vertical wall 86 overlap in the temporary joining step S3.

[0071] In the fifth vertical wall 84 of the frame part 83 shown in FIG. 30, a groove 37 into which one end 11 of the plate material 5 is fitted is formed. In the fifth vertical wall 84 of the frame part 83 shown in FIG. 31, a stepped portion 46 with which one end 11 of the plate material 5 engages is formed. Even when forming the frame part 83 having only the first and second closing surfaces 81 and 82 as shown in FIGS. 29 to 31, it is possible to produce a highly rigid frame part having a plurality of closing surfaces with high productivity in the same manner as in the embodiments shown in FIGS. 1 to 28, and it is possible to provide a method for manufacturing a frame part formed by roll forming that can suppress springback by a simple method and improve welding accuracy.

[0072] In addition to being carried out by the blind rivets 33 and the clamps 71 and 72 as described above, the temporary joining process can be carried out using an adhesive (not shown). This main joining process of continuously welding may be MIG welding, friction stir joining, etc. in addition to laser welding. In the above-described embodiment, the frame part 8 has an outer peripheral frame 17 formed so as to surround the ladle-shaped part 16 through the bottom side and the opening side of the ladle from the tip of the handle of the ladle. However, it may be formed so as to surround the ladle-shaped part 16 through the opening side and the bottom side of the ladle, and is not limited to the outer peripheral frame 17, and there may be an opening. For example, after forming the ladle-shaped part 16, roll forming is performed in the order of the fourth vertical wall 28 → the fourth horizontal wall 27 → the third vertical wall 26 to form the outer frame part 18. This outer frame part 18 is formed in a cross-sectional cup shape that opens downward and houses the ladle of the ladle-shaped part 16, and forms two closing surfaces (the first and second closing surfaces 13 and 14) that cooperate with the ladle to sandwich the T-shaped joint part 12. In the above embodiment, the third closing surface 15 is provided on the left side of the handle of the ladle (the second vertical wall 24), but it may be provided on the right side of the handle of the ladle, and the fourth and fifth closing surfaces may be provided vertically or horizontally. Also, with respect to the ladle-shaped part 16, roll forming was performed clockwise, but it may be performed counterclockwise.

Explanation of Reference Numerals

[0073] 5... Plate material, 8, 51, 83... Frame parts, 9... Rivet driving device, 11... One end, 12... T-shaped joint, 13... First closing surface part, 14... Second closing surface part, 15... Third closing surface part, 16... Handle ladle-shaped part, 17... Outer peripheral frame, 18... Outer frame part, 31... First overlapping part, 32... Second overlapping part, 33... Blind rivet, 34... Rivet hole, 37... Groove, 46... Step part, 71... Clamp, 72... Clamp (clamping member), S1... Cutting process, S1A... Drilling process, S2... Forming process, S3... Temporary joining process, S4... Waiting process, S5... Final joining process, S6... Groove forming process, S7... Step part forming process.

Claims

1. A cutting step of cutting a metal plate material into a predetermined length, a forming step of forming a frame component having at least two closed cross-sectional portions including a T-shaped joint portion with a T-shaped cross-section where one end of the plate material abuts and two closed cross-sectional portions sandwiching the T-shaped joint portion by performing roll forming so as to surround one end of the plate material, a temporary joining step of performing a temporary joining process in which the shape of the frame component is retained, a waiting step of waiting for the frame component after the temporary joining process is completed, and a main joining step of continuously welding the frame component waiting in the waiting step, wherein the cutting step is performed either before the forming step and after the temporary joining step and before the waiting step, and the main joining is performed on another frame component in the waiting step when the frame component is being formed in the forming step. A method for manufacturing a frame component formed by roll forming, characterized by this.

2. In the method for manufacturing a frame component formed by roll forming according to Claim 1, the frame component has a ladle-shaped portion formed in a ladle-shaped cross-section with one end located at the open end of the ladle, and an outer frame portion formed in a cup-shaped cross-section for accommodating the ladle and forming two closed cross-sectional portions that sandwich the T-shaped joint portion in cooperation with the ladle, and the temporary joining step is carried out by performing the temporary joining process at least on a portion where the outer frame portion overlaps the bottom of the ladle and a portion where the outer frame portion overlaps the handle of the ladle. A method for manufacturing a frame component formed by roll forming, characterized by this.

3. In the method for manufacturing a frame component formed by roll forming according to Claim 2, further, a drilling step of drilling rivet holes at positions on the plate material where the temporary joining process is to be performed before the forming step is carried out, and the temporary joining step is carried out by driving rivets into the rivet holes using a rivet driving device installed on the downstream side in the feeding direction of the frame component from the roll forming device for performing the forming step. A method for manufacturing a frame component formed by roll forming, characterized by this.

4. In the method for manufacturing a frame component formed by roll forming according to Claim 3, in the roll forming in the forming step, forming stress is applied so that the frame component is compressed and deformed, The temporary joining process in the temporary joining step is carried out when the frame part is restored to its normal shape due to springback caused by the forming stress, and is a manufacturing method for a frame part formed by roll forming.

5. In the manufacturing method for a frame part formed by roll forming according to claim 4, before roll forming is carried out on the sheet material in the forming step, a groove forming step of forming a groove into which one end fits is carried out on the sheet material, in the forming step, the T-shaped joint is formed into its final shape by fitting one end into the groove, and is a manufacturing method for a frame part formed by roll forming.

6. In the manufacturing method for a frame part formed by roll forming according to claim 4, before roll forming is carried out on the sheet material in the forming step, a step forming step of forming a step so that a part of the sheet material is biased in one direction in the thickness direction is carried out, in the forming step, the T-shaped joint is formed into its final shape by engaging one end with the step, and is a manufacturing method for a frame part formed by roll forming.

7. In the manufacturing method for a frame part formed by roll forming according to claim 5 or claim 6, the temporary joining process in the temporary joining step is carried out in a state where the T-shaped joint is formed into its final shape, and is a manufacturing method for a frame part formed by roll forming.

8. In the manufacturing method for a frame part formed by roll forming according to claim 7, the main joining step is carried out by welding the T-shaped joint from the outside of the frame part by laser welding, and is a manufacturing method for a frame part formed by roll forming.

9. In the manufacturing method for a frame part formed by roll forming according to claim 8, the laser welding is also carried out at a position adjacent to the rivet driven by the rivet driving device in the temporary joining step in the longitudinal direction of the frame part, and is a manufacturing method for a frame part formed by roll forming.

10. In the manufacturing method for a frame part formed by roll forming according to claim 1, the cutting step is carried out before the forming step is carried out, The temporary joining process carried out in the temporary joining step is carried out by clamping, with a clamp, a portion where the plate materials are overlapped at both longitudinal ends of the frame part, and is a method for manufacturing a frame part formed by roll forming, characterized in that.

11. In the method for manufacturing a frame part formed by roll forming according to claim 1, the temporary joining process carried out in the temporary joining step is carried out by sandwiching and tightening, with a pressing member, one outer end portion and the other outer end portion of the frame part such that the other end portion of the plate material is sandwiched therebetween, and is a method for manufacturing a frame part formed by roll forming, characterized in that.

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