Bead forming method

Abstract

Provided is a bead forming method capable of better suppressing warpage generated during bead formation. 【Solution means】The bead forming method includes a beading step of forming a bead (Wb) on a plate material (W), and a correction step of sandwiching a predetermined correction range (K) that moves away from the bead (Wb) in the thickness direction with the inner end being a correction line (P2a) that bites into the side of the bead (Wb) by a predetermined distance (α) from a connection line (P1a) where a flat part (Wp) and the bead (Wb) are connected in the plate material (W) on which the bead (Wb) is formed, and crushing it.

Description

Technical Field

[0001] The present invention relates to a bead forming method.

Background Art

[0002] Patent Document 1 describes a bead forming method in which bead forming is performed on a metal plate to form beads, and then coining is performed on the connection portion between the outer surface of the beads and the flat portion. This method is said to be able to suppress warping when a product having beads is cut out because the internal stress generated by the bead forming is made uniform by the coining. Patent Document 2 describes that bead forming is performed using a roll forming die that is a rotating roller-shaped die and punch.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the bead forming method described in Patent Document 1, when the width of the beads becomes large, warping suppression may not be sufficient. Therefore, a bead forming method that can better suppress warping generated during bead forming is desired.

Means for Solving the Problems

[0005] To solve the above problems, one aspect of one or more embodiments of the present invention is a beading method including a beading step of forming a bead on a plate material, and a correction step of sandwiching a predetermined correction range that moves away from the bead with an inner end being a correction line that bites into the side of the bead by a predetermined distance from a connection line where a flat portion and the bead are connected in the plate material on which the bead is formed, and crushing it in the thickness direction.

Advantages of the Invention

[0006] According to the beading method according to one or more embodiments of the present invention, an effect that warpage generated during beading can be suppressed better can be obtained.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5

Figure 6A

Figure 6B

Figure 6C

Figure 7A

Figure 7B

Figure 8A

Figure 8B

Mode for Carrying Out the Invention

[0008] A bead forming method which is an aspect of one or more embodiments of the present invention will be described. This bead forming method includes a beading process (see FIG. 1) for forming a bead Wb on a plate material W, and a warpage reduction process performed on the plate material W on which the bead Wb is formed. The processing method of the beading process is not limited, and here, a method performed by the roll forming die set described in Patent Document 2 will be described.

[0009] As shown in FIG. 1, the roll forming die set 1 used in one aspect of the present invention is a set of a lower roll die 1D and an upper roll die 1P. The roll forming die set 1 is formed symmetrically with respect to the center line CL1 extending vertically in FIG. 1. The lower roll die 1D rotates around a horizontally extending rotation axis CL1D, and integrally has a push-up roll 1D2 and lower pressing rolls 1D1, 1D3. The push-up roll 1D2 is formed to have a curved surface that protrudes maximally radially outward such that the circumferential surface shape in the axial direction has the maximum diameter at the center, and lower pressing rolls 1D1, 1D3 having the same outer diameter are connected and formed at both axial ends of the push-up roll 1D2.

[0010] The upper roll die 1P is disposed above the lower roll die 1D so as to move up and down by a driving unit (not shown). The upper roll die 1P is formed as a roll that rotates around a horizontally extending rotation axis CL1P. The upper roll die 1P has a relief shaft portion 1P2 and upper pressing rolls 1P1, 1P3 at positions corresponding to the push-up roll 1D2 and the lower pressing rolls 1D1, 1D3 of the lower roll die 1D, respectively.

[0011] When bead forming is performed, the plate material W, which is the member to be processed, is inserted between the lower roll die 1D and the raised upper roll die 1P. Then, the upper roll die 1P descends, and while sandwiching the plate material W between the lower roll die 1D, the roll forming die set 1 is relatively moved in the extending direction of the bead Wb. As a result, the portion between the upper pressing rolls 1P1, 1P3 is lifted by the push-up roll 1D2 to form the bead Wb. The bead Wb may be formed by fixing the roll forming die set 1 and moving the plate material W, or by fixing the plate material W and moving the side of the roll forming die set 1. Alternatively, it may also be formed by moving both the roll forming die set 1 and the plate material W.

[0012] As shown in FIG. 1, the plate material W is sandwiched between the upper pressing rolls 1P1, 1P3 and the lower pressing rolls 1D1, 1D3, and the relief shaft portion 1P2 is formed with a small diameter that does not interfere with the bead Wb that is lifted upward by the push-up roll 1D2, and is adapted to escape from the bead Wb. And the inner end positions of each of the upper pressing roll 1P1 and the upper pressing roll 1P3 become the bead connection positions P1 at the boundary (shape change position) between the bead Wb and the flat portion Wp. At the bead connection position P1, a connection line P1a, which is a bending line in the extending direction of the bead Wb, is formed.

[0013] In one aspect of the bead forming method, a camber reduction process is performed after the above-described beading process. Next, this camber reduction process will be described with reference to FIGS. 2A to 4. FIG. 2A is a first view showing a camber reduction process using a camber reduction single die set 2 in one aspect of the present invention. FIG. 2B is a second view showing a camber reduction process using the camber reduction single die set 2. FIG. 3 is an enlarged cross-sectional view showing the vicinity of the bead connection position P1 before and after the camber reduction process, where FIG. 3(a) shows before the camber reduction process and FIG. 3(b) shows after the camber reduction process. FIG. 4 is a plan view showing the plate material W after performing a camber reduction process on the formed bead Wb.

[0014] In one aspect of the bead forming method, the camber reduction process is performed by, for example, a camber reduction single die set 2 (hereinafter simply referred to as the single die set 2) shown in FIG. 2A.

[0015] The single die set 2 is a set of a lower roll die 2D and an upper roll die 2P. The lower roll die 2D rotates around a horizontally extending rotation axis CL2D and has a lower pressing roll 2D2 with a constant outer diameter and shaft portions 2D1 and 2D3 that are smaller in diameter and extend axially at both ends of the lower pressing roll 2D2. The upper roll die 2P moves up and down by a driving portion (not shown) and rotates around a rotation axis CL2P that extends parallel to the rotation axis CL2D. The upper roll die 2P has an upper pressing roll 2P2 with a constant outer diameter and shaft portions 2P1 and 2P3 that are smaller in diameter and extend axially at both ends of the upper pressing roll 2P2.

[0016] With the upper roll die 2P of this single die set 2 in the raised state, the plate material W with the bead Wb formed is inserted between it and the lower roll die 2D in a direction in which the extending direction of the bead Wb (the direction perpendicular to the plane of FIG. 2A) is perpendicular to the rotation axis CL2D, and positioned as follows. That is, the axial arrangement position of the upper roll die 2P is set such that one edge thereof bites into the correction position P2 that is inside the bead Wb compared to one bead connection position P1 of the bead Wb. This biting distance (amount) is defined as the biting amount α as shown in FIG. 3(b).

[0017] Further, the position of the bead Wb of the upper roll die 2P in the extending direction is generally set at the end of the bead connection position P1 on one side in the width direction of the bead Wb. Next, the upper roll die 2P is lowered (see arrow DR2), and while sandwiching the flat portion Wp of the plate material W between the upper pressing roll 2P2 and the lower pressing roll 2D2, the single die set 2 is relatively moved in the extending direction of the bead Wb with respect to the plate material W. Also, in the state where the upper roll die 2P is lowered, the gap in the height direction between the upper pressing roll 2P2 and the lower pressing roll 2D2 is set to be the same as or slightly smaller than the thickness of the plate material W.

[0018] As a result, as shown in FIG. 2B, the upper pressing roll 2P2 and the lower pressing roll 2D2 are corrected so that the portion from the bead connection position P1 of the bead Wb to the correction position P2 that has dug inward becomes flat while rotating. Here, correction means a process of crushing the plate material W to the original thickness or a thickness slightly smaller than that. For example, the amount of crushing set as the lowering position for the upper pressing roll 2P2 is about 0.2 mm. In this case, the amount of crushing (compression) actually reflected in the plate material W after the crushing process is about 0.1 mm when the plate thickness is 1.0 mm. In other words, the plate thickness is crushed and compressed by about 10%. The portion where this warpage reduction process is performed is shown as the range LN of the thick solid line in FIG. 2B for convenience. When the correction of the bead connection position P1 on one side is completed, the correction of the bead connection position P1 on the opposite side in the width direction of the bead Wb is performed in the same procedure.

[0019] As shown in FIG. 3(a), the shape of the upper surface W1 that becomes the outer surface of the bead Wb before performing the warpage reduction process has a bent shape in which the bead Wb side rises steeply at the bead connection position P1 that is the boundary between the flat flat portion Wp and the curved bead Wb in the cross section. On the other hand, the cross-sectional shape of the upper surface W1 of the same portion subjected to the warpage reduction process with the biting amount α has a correction line P2a that is a bent line extending in the extending direction (perpendicular to the paper surface) of the bead Wb formed at the correction position P2 that has entered inward by the biting amount α from the bead connection position P1. Due to the warpage reduction process, the portion between the connection line P1a formed at the bead connection position P1 and the correction line P2a is plastically deformed to be generally flat.

[0020] Also, as shown in Fig. 3(a), the lower surface W2, which becomes the inner surface of the plate material W before performing the warpage reduction process, has a flat range M, which is the range that becomes flat due to the pushing-up action of the pushing-up roll 1D2, up to the position Q1 outside (on the side opposite to the bead Wb) of the bead connection position P1. The lower surface W2 is a curved surface that rises gently so that the plate thickness decreases from the position Q1 toward the bead Wb side.

[0021] On the other hand, as shown in Fig. 3(b), the lower surface W2 of the same part that has been subjected to the warpage reduction process with the biting amount α is pressed against the lower pressing roll 2D2 up to the correction position P2 by the upper pressing roll 2P2. Therefore, the flat range M extends generally up to the position Q2 corresponding to the correction position P2. This change in shape indicates that a part of the metal that had been forced to plastically flow toward the center side of the bead Wb as shown by the arrow DR3a by the beading process plastically flows from the bead Wb side toward the original flat part Wp side as shown by the arrow DR3b due to the warpage reduction process. Therefore, it is presumed that the residual stress generated in the vicinity of the bead connection position P1 due to the beading process is partially released and reduced by the warpage reduction process.

[0022] For the bead Wb subjected to the camber reduction process, as shown in FIGS. 3(b) and 4, at the correction position P2, a correction line P2a formed by the edge of the upper pressing roll 2P2 remains as a mark. Further, as shown in FIG. 4, a correction range K, which is a crushed range corresponding to the contact range of the upper pressing roll 2P2, is set as a predetermined range that moves away from the bead Wb as an inner end from the correction line P2a, and the range is slightly visible due to being crushed. The correction range K is a portion where the plate thickness is compressed by, for example, about 10% as described above. Further, the width of the correction range K corresponds to the width of the upper pressing roll 2P2. The larger (wider) this width is, the more uniformly the metal plastically flowing from the bead Wb side toward the flat portion Wp side is leveled without unevenness, and thus the effect of reducing the residual stress is high. When the single die set 2 is used for the camber reduction process, the process is performed at the bead connection position P1 that is one widthwise edge of the bead Wb and the bead connection position P1 that is the other widthwise edge, and the camber reduction process is not performed on the curved portions at both ends of the bead Wb.

[0023] To confirm the speculation that the residual stress is reduced by the above-described camber reduction process, the change in the camber reduction effect when the camber reduction process is performed on the bead Wb of the same shape while changing the indentation amount α was confirmed by a test, which will be described next. The test was performed including a comparative product on which the camber reduction process was not performed.

[0024] The content of the camber reduction effect confirmation test is as follows. (Sheet material W) Material: SECC (Electrolytic Galvanized Steel Sheet) Dimensions: 130 mm × 300 mm Thickness: 1.0 mm

[0025] (Formed bead Wb) Length: 240 mm Width: 12.7 mm Height: Maximum 3.0 mm Number: 2 Pitch: 80 mm The width of the bead Wb is the widthwise distance between a pair of bead connection positions P1 of the bead Wb.

[0026] Specimen Comparative Example: Without warpage reduction processing (beading processing only) Specimen 1: With warpage reduction processing, α = 0.45 mm Specimen 2: With warpage reduction processing, α = 0.65 mm Specimen 3: With warpage reduction processing, α = 0.85 mm

[0027] Measuring instrument 3D scanner type three-dimensional measuring instrument VL-500 manufactured by Keyence Corporation

[0028] Measuring method Place the specimen on the stage of the measuring instrument with the convex direction of the bead Wb facing up, and measure the height distribution of the specimen to be measured. Also, extract four height points at the central part A and the four corner parts B1 to B4 of the specimen in the height distribution as distance measurement points. Subtract the plate thickness of the specimen to be measured from the value of each obtained distance measurement point to obtain the warpage value of each distance measurement point. Therefore, the reason why the warpage value may be negative is that the plate thickness is affected by the processing.

[0029] The distributions of the warpage values obtained in the confirmation test are shown in FIGS. 5(a) to (d). FIG. 5(a) shows the comparative product without warpage reduction processing, FIG. 5(b) shows Specimen 1 (α = 0.45 mm), FIG. 5(c) shows Specimen 2 (α = 0.65 mm), and FIG. 5(d) shows Specimen 3 (α = 0.85 mm). The distributions of the warpage values are displayed in the following three stages outside the bead Wb. Since the deformation of the bead Wb is large, the distribution is not shown. First range AR1: Less than +1.0 mm Second range AR2: +1.0 mm or more and less than +2.0 mm Third range AR3: +2.0 mm or more

[0030] As shown in FIG. 5(a), it can be seen that in the comparative product, large warpage in the third range AR3 occurs near both edges in the extending direction of the bead Wb of the plate material W, and warpage in the second range AR2 occurs over a wide range inside each of the third ranges AR3. On the other hand, in Embodiments 1 and 2 shown in FIGS. 5(b) and 5(c), although warping occurs only at one end of the plate material W in the second range AR2, the warping in other ranges is suppressed to the warping in the first range AR1, and it is clear that the warping is significantly suppressed as compared with the comparative product.

[0031] In addition, although the warping of the product shown in FIG. 5(d) is suppressed as compared with the comparative product, and the second range AR2 occurring at one end of the plate material W is further reduced, the second range AR2 occurs in the central portion, and a so-called reverse warping tendency is recognized.

[0032] FIG. 6A is Table 1 showing the warping values of the central portion A and the four corner portions B1 to B4, which are the four distance measurement points shown in FIGS. 5(a) to 5(d). FIG. 6B is Table 2 showing the warping values of the corner portions B1 to B4 with respect to the central portion A, that is, the differences between the warping values of the corner portions B1 to B4 and the warping value of the central portion A, and the average value (AVE.). FIG. 6C is a graph of the average value of Table 2.

[0033] As is clear from FIG. 6C, the overall warping of the plate material W can reduce the warping value to less than half of that without performing the warping reduction process by performing the warping reduction process with the indentation amount α in the range up to 0.85 mm. It is also clear that the tendency of reverse warping occurs as the indentation amount α increases. In this example, in the range of the indentation amount α of 0.45 mm to 0.65 mm, the warping can be more balanced and reduced to a small amount. Thus, although the tendency of reverse warping occurs as the indentation amount α increases, it was confirmed that if the indentation amount α is less than twice the plate thickness of the plate material W, the effect of reducing the warping can be obtained as compared with the case where the warping reduction process is not performed.

[0034] As described above, according to the bead forming method of one aspect of one or more embodiments of the present invention, the warping generated in the plate-shaped product by the bead forming can be more favorably suppressed.

[0035] One aspect of one or more embodiments of the present invention is not limited to the above-described configuration, and may be a modification within a range not departing from the gist of the present invention.

[0036] (Modification Example 1) The single die set 2 used for the warpage reduction process may be a warpage reduction double die set 3 (hereinafter, double die set 3). The double die set 3 will be described below with reference to FIGS. 7A and 7B. FIG. 7A is a diagram showing the warpage reduction process by the double die set 3. FIG. 7B is a partially cut-away cross-sectional view showing the plate material W after the warpage reduction process is performed using the double die set 3.

[0037] While the single die set 2 corrects only the vicinity of the bead connection position P1 on one side of the bead Wb, the double die set 3 can correct the bead connection positions P1 on both sides of the bead Wb simultaneously. As shown in FIG. 7A, the double die set 3 is a set of a lower roll die 3D and an upper roll die 3P. The double die set 3 is formed symmetrically with respect to the center line CL3 extending vertically in FIG. 7A.

[0038] The lower roll die 3D rotates around a horizontally extending rotation axis CL3D and is a lower pressing roll having a constant outer diameter. The upper roll die 3P moves up and down by a driving part (not shown) and rotates around a rotation axis CL3P extending parallel to the rotation axis CL3D. The upper roll die 3P has an upper pressing roll 3P1 and an upper pressing roll 3P3 having a constant outer diameter and arranged axially spaced apart, and a connecting shaft part 3P2 connecting them with a small outer diameter, and is integrally formed. The lower roll die 3D is formed with a length exceeding the length between both ends of the upper pressing roll 3P1 and the upper pressing roll 3P3, and is arranged to face so as to include the range of that length.

[0039] Specifically, the width L4, which is the axial interval between the correction positions P3, P3 which are the inner edge portions of the upper pressing rolls 3P1, 3P3 respectively, is set shorter than the width L3 which is the distance between the bead connection positions P1, P1 in the width direction of the bead Wb. Specifically, the width L4 is shorter than the width L3 by twice the amount of penetration α2. In the warpage reduction process, the double die set 3 is positioned and arranged to penetrate into the bead Wb by the amount of penetration α2 with respect to each of the bead connection positions P1, P1 on both sides in the width direction.

[0040] In the camber reduction process using the double die set 3, as in the case of using the single die set 2, with the upper roll die 3P of the double die set 3 raised, a plate material W with a bead Wb formed therebetween is inserted between the upper roll die 3P and the lower roll die 3D in such a way that the extending direction of the bead Wb (the direction perpendicular to the plane of FIG. 7A) is perpendicular to the rotation axis CL3D, and then positioned as follows. That is, the axial position where the upper roll die 3P is arranged is set such that it enters inward from both bead connection positions P1 of the bead Wb by an amount α2 of indentation respectively. Also, the positions of the rotation axes CL3D and CL3P in the extending direction of the bead Wb are generally at the ends of the linear bead connection position P1 of the bead Wb. Next, the upper roll die 3P is lowered (see arrow DR5 in FIG. 7A), and while sandwiching the flat portion Wp of the plate material W between the upper pressing rolls 3P1 and 3P3 and the lower roll die 3D, the double die set 3 is relatively moved with respect to the plate material W in the extending direction of the bead Wb. In the state where the upper roll die 3P is lowered, the height direction gap between the upper pressing rolls 3P1 and 3P3 and the lower roll die 3D is set to be the same as or slightly smaller than the plate thickness of the plate material W.

[0041] Thereby, as shown by arrow DR6 in FIG. 7A, the upper pressing rolls 3P1 and 3P3 and the lower roll die 3D rotate around the rotation axes CL3P and CL3D respectively, and simultaneously perform straightening processing on the bead connection positions P1 on both sides in the width direction of the bead Wb. In the straightening process, the portion from each bead connection position P1 to the straightening position P3 that indents inward by an amount α2 is straightened so as to be flat, and a straightening line P3a is formed. Therefore, the time required for the camber reduction process can be halved.

[0042] By making it possible to adjust the axial interval between the upper pressing rolls 3P1 and 3P3, for beads Wb of any width, camber reduction processing can be simultaneously performed in the vicinity of the bead connection positions P1 on both sides of the bead Wb with an arbitrary amount of indentation α, and the versatility of the double die set 3 is improved.

[0043] (Modification 2) It may also be a composite die set 5 in which a roll forming die set 1 used for beading and a double die set 3 used for warpage reduction are integrated. Next, the composite die set 5 will be described with reference to FIGS. 8A and 8B. FIG. 8A is a side view for explaining the processing using the composite die set 5. FIG. 8B is a diagram for explaining the difference between the width L5 which is the roll interval of the beading die set 50 of the composite die set 5 and the width L6 which is the roll interval of the warpage reduction die set 60.

[0044] As shown in FIG. 8A, the composite die set 5 has a frame body 53, a beading die set 50, and a warpage reduction die set 60. The frame body 53 is formed in a frame shape and supports the beading die set 50 on the upstream side in the relative conveyance direction (arrow DR6) of the plate material W, and supports the warpage reduction die set 60 on the downstream side thereof.

[0045] The beading die set 50 has a lower roll die 5D fixed to the support frame 52 of the frame body 53 and an upper roll die 5P supported so as to be vertically movable by the elevating frame 51 of the frame body 53. The vertical movement of the upper roll die 5P is performed by a drive unit (not shown). The warpage reduction die set 60 has a lower roll die 6D fixed to the support frame 62 of the frame body 53 and an upper roll die 6P supported so as to be vertically movable by the elevating frame 61 of the frame body 53. The vertical movement of the upper roll die 6P is performed independently of the vertical movement of the upper roll die 5P by a drive unit (not shown).

[0046] The configuration of the beading die set 50 is the same as that of the roll forming die set 1, and the configuration of the warpage reduction die set 60 is the same as that of the double die set 3. That is, the upper roll die 5P of the beading die set 50 has upper pressing rolls 5P1 and 5P3 corresponding to the upper pressing rolls 1P1 and 1P3. Further, the lower roll die 5D has lower pressing rolls 5D1 and 5D3 and a pushing-up roll 5D2. On the other hand, the warpage reduction die set 60 has upper pressing rolls 6P1 and 6P3 corresponding to the upper pressing rolls 3P1 and 3P3 and a lower roll die 6D corresponding to the lower roll die 3D.

[0047] As shown in FIG. 8B, the beading die set 50 and the warp reduction die set 60 are arranged such that their respective rotation axes CL5D, CL5P, CL6D, and CL6P are parallel. Also, they are arranged symmetrically in the vertical direction in FIG. 8B with respect to the center line CL5 which is the center in the axial direction of each. And with respect to the width L5 which is the separation distance in the direction of the rotation axis CL5P of the upper pressing rolls 5P1 and 5P3, the width L6 which is the separation distance in the direction of the rotation axis CL6P of the upper pressing rolls 6P1 and 6P3 is set to be shorter by twice the amount of penetration α2 that has penetrated by the amount of penetration α2 on one side.

[0048] As shown in FIG. 8A, a flat plate-shaped plate material W as a workpiece is inserted into the composite die set 5 from the side of the beading die set 50 and relatively moved, whereby first, a bead Wb is formed by the beading die set 50. This bead Wb is shown as bead Wba in FIG. 8A. The vicinity parts of the bead connection positions P1 on both sides in the width direction of the formed bead Wba are immediately subjected to warp reduction processing simultaneously on both sides of the bead Wba by the warp reduction die set 60 adjacent to the downstream side of the beading die set 50 and corrected, and a correction line P6a is formed (refer to the range LN in FIG. 8A).

[0049] In this way, by using the composite die set 5, the beading process and the warp reduction process are substantially simultaneously executed in one process, so that the product can be manufactured in a shorter time.

[0050] For the composite die set 5, the interval in the direction of the rotation axis CL5P of the upper pressing rolls 5P1 and 5P3 of the beading die set 50 and the interval in the direction of the rotation axis CL6P of the upper pressing rolls 6P1 and 6P3 of the warp reduction die set 60 may be adjusted arbitrarily respectively. Thereby, the versatility of the composite die set 5 is improved, and a bead Wb with an arbitrary width can be formed and the warp reduction process can be executed with an arbitrary amount of penetration α2. Also, each can be executed in substantially one process.

[0051] The beading process is not limited to being executed with the roll forming die set described above. The warpage reduction process is also not limited to the method of sandwiching and crushing the correction range between the pair of rolls described above. For example, a method of crushing the correction range by performing multiple times of crushing along the bead Wb by coining may be used.

[0052] As described in detail above, the bead forming method according to one or more embodiments of the present application includes a beading step of forming a bead Wb on a plate material W, and a correction step of sandwiching and crushing a predetermined correction range K in the thickness direction from the outside of a correction line P2a that has bitten into the side of the bead Wb by a predetermined distance α from a connection line P1a where a flat portion Wp and the bead Wb are connected in the plate material W on which the bead Wb is formed.

[0053] According to this, the residual stress of the plate material W is favorably released by the correction step, and the warpage generated along with the bead formation can be more favorably suppressed.

[0054] Further, in the above-described embodiment, the correction step may be such that the plate material W is sandwiched between a first roll 2P2 that rolls along the bead Wb on a first surface W1 on the side where the bead Wb is convex and a second roll 2D2 that is disposed opposite to the first roll 2P2 and rolls along the bead Wb on a second surface W2 on the side opposite to the first surface W1, and is relatively moved in the extending direction of the bead Wb while being crushed while being positioned such that the edge of the first roll 2P2 is located at the correction line P2a.

[0055] According to this, the warpage reduction process can be continuously executed by the relative movement of the plate material W, and the time required for the warpage reduction process can be shortened.

[0056] Furthermore, the first roll 2P2 may be respectively disposed on one side and the other side in the width direction of the bead Wb, so that both correction ranges K in the width direction of the bead Wb are simultaneously crushed in the correction step.

[0057] According to this, since a pair of correction ranges K on both sides in the width direction of the bead Wb can be crushed by one relative movement, the time required for the warpage reduction process can be made shorter.

[0058] Further, when the bead Wb is formed by the roll forming die set 1 and the first roll 2P2 and the second roll 2D2 are included in the warp reduction die set 2, the roll forming die set 1 and the warp reduction die set 2 may be integrally arranged in series in the relative movement direction of the plate material W so that both the beading process and the correction process can be executed by a single relative movement of the plate material W.

[0059] As a result, since both the formation of the bead Wb and the warp reduction process can be executed by a single relative movement of the plate material W, the overall processing time including the beading process and the warp reduction process can be shortened.

Explanation of reference numerals

[0060] 1 Roll forming die set 1D Lower roll die 1D1, 1D3 Lower pressing roll 1D2 Pushing-up roll 1P Upper roll die 1P1, 1P3 Upper pressing roll 1P1a, 1P3a Edge 1P2 Relief shaft portion 2 Warp reduction single die set (single die set) 2D Lower roll die 2D1, 2D3 Shaft portion 2D2 Lower pressing roll (second roll) 2P Upper roll die 2P1, 2P3 Shaft portion 2P2 Upper pressing roll (first roll) 2P2a Edge 3 Warp reduction double die set (double die set) 3D Lower roll die 3P Upper roll die 3P1, 3P3 Upper pressing roll 3P1a, 3P3a Edge 3P2 Connecting shaft portion 5 Composite die set 50 Beading die set 5P Upper roll die Upper pressing rolls 5P1 and 5P3 Lower roll die 5D Lower pressing roll 5D1 Lifting roll 5D2 Lifting frames 51 and 61 Support frames 52 and 62 Frame body 53 Warp reduction die set 60 Upper roll die 6P Upper pressing rolls 6P1 and 6P3 Edges 6P1a and 6P3a Lower roll die 6D Central part A First range to third range AR1 to AR3 Corner parts B1 to B4 Center lines CL1, CL3, and CL5 CL1D, CL1P, CL2D, CL2P, CL3D, CL3P, CL5D, C Correction range K Rotation axes L5P, CL6D, and CL6P Range LN Widths L3, L4, L5, and L6 Flat range M Bead connection position P1 Connection line P1a Correction positions P2 and P3 Correction lines P2a, P3a, and P6a Positions Q1 and Q2 Sheet material W Beads Wb and Wba Flat part Wp Upper surface (outer surface) (first surface) W1 Lower surface (inner surface) (second surface) W2 Penetration amounts α and α2

Claims

1. A beading step of forming a bead on a plate material, A correction step of sandwiching and crushing a predetermined correction range that moves away from the bead with the inner end being a correction line that bites into the side of the bead by a predetermined distance from a connection line where a flat portion and the bead are connected in the plate material on which the bead is formed, in the thickness direction, A bead forming method including this.

2. The correction step is, Between a first roll that rolls along the bead on a first surface on the side where the bead is convex and a second roll that is arranged opposite to the first roll and rolls along the bead on a second surface on the side opposite to the first surface, while sandwiching and crushing the plate material in a state where the edge of the first roll is positioned at the correction line, and relatively moving it in the extending direction of the bead. The bead forming method according to Claim 1.

3. The first roll is arranged on one side and the other side in the width direction of the bead, respectively, and the bead forming method according to Claim 2, wherein both correction ranges in the width direction of the bead are simultaneously crushed in the correction step.

4. The bead is formed by a roll forming die set, When the first roll and the second roll are included in a camber reduction die set, The roll forming die set and the camber reduction die set are integrally arranged in series in the relative movement direction of the plate material, and the bead forming method according to Claim 3, wherein both the beading step and the correction step can be executed by one relative movement of the plate material.

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