Method for manufacturing a stamped part

Abstract

The present invention relates to a method for manufacturing stamped parts and stamped parts, the objective of which is to process stamped parts comprising high-strength materials and having a cap-shaped portion and a flange portion without cracking (fracture, cracking) during the forming process. The present invention is a method for manufacturing a stamped part 1 having a cap-shaped portion 9 and a flange portion 11, comprising: a first forming step, forming material until the depth of the cap-shaped portion 9 reaches an intermediate depth; a second forming step, forming material until the depth of the cap-shaped portion 9 reaches a target depth; a correction step, removing excess portion 27 at the outer periphery of the flange forming portion 29; and a flange forming step, forming the flange portion 11.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a stamped part and the stamped part itself, and more particularly to a method for manufacturing a stamped part having a cap-shaped portion and a flange portion, and the stamped part itself. Background Technology

[0002] In recent years, high strength has been required for the bodies of automobiles and other vehicles. To meet this requirement, high-tensile steel sheets (high-strength materials) have been used. Through the use of high-strength materials, the ultra-high tensile strength of the structural components (body parts) of the vehicle body has been improved.

[0003] For example, in vehicle body parts, the frame often uses a cross-section with a shape resembling a cap or a U-shape. Sometimes, a flange is provided at the end of these parts (the cap-shaped portion), which is then joined to the target part by welding or other means. In the past, to facilitate the forming of this flange, it was divided into multiple parts by cutting. However, to improve the deformation strength during a collision, there are cases where the flange at the end of the cap-shaped portion is formed integrally with the cap-shaped portion, extending continuously from one part of the lower part to another.

[0004] As a method for manufacturing a stamped part including a cap-shaped portion and a flange portion at the end, for example, the method described in Patent Document 1 is known.

[0005] In the method for manufacturing a stamped part described in Patent Document 1, during the forming of the cap-shaped part, a wavy pleated part is formed in the part that becomes the flange part, and then the pleated part is extended to form the flange part.

[0006] [Existing Technical Documents]

[0007] [Patent Literature]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2015-081036. Summary of the Invention

[0009] [The problem the invention aims to solve]

[0010] Furthermore, if ordinary steel sheet is used, the manufacturing method of the stamped part described in Patent Document 1 can be implemented. However, in high-strength materials, the elongation at fracture is approximately 10%, for example, for a 980 MPa material. Therefore, even if the manufacturing method of the stamped part described in Patent Document 1 is implemented in high-strength materials, cracking (fracture, crazing) may occur during the forming process, making it impossible to process.

[0011] The purpose of this invention is to provide a stamped part comprising a high-strength material and having a cap-shaped part and a flange part, and a method for manufacturing the stamped part, which can be processed without cracking (fracture, cracking) during the forming process.

[0012] [Technical means to solve the problem]

[0013] One aspect of the present invention is a method for manufacturing a stamped part, the stamped part comprising a high-strength material and having: a cap-shaped portion formed by a cross-sectional shape of a plane orthogonal to the length direction; and a flange portion, which, when viewed in the length direction of the cap-shaped portion, extends from one end of the cap-shaped portion to the other end along a direction intersecting the length direction of the cap-shaped portion on the convex side of the cap-shaped portion; the method for manufacturing the stamped part includes: a first forming step, forming a flat material of a specific shape until the depth of the cap-shaped portion reaches a mid-depth; a second forming step, forming the material formed in the first forming step until the depth of the cap-shaped portion reaches a target depth; a correction step, removing excess portion from the portion other than the cap-shaped portion formed in the first and second forming steps, i.e., the outer periphery of the flange forming portion; and a flange forming step, after removing the excess portion using the correction step, bending the flange forming portion in such a way that it extends along a direction intersecting the length direction of the cap-shaped portion to form the flange portion.

[0014] Alternatively, in the second forming step, the flange is bent at the boundary between the flange forming portion and the surplus portion.

[0015] Alternatively, in the flange forming step, the time when the central part of the flange forming portion begins to bend is later than the time when the two ends of the flange forming portion begin to bend.

[0016] Alternatively, the stamped part may be formed by continuous stamping using a feed rod located on the opposite side of the flange.

[0017] Alternatively, the stamped parts can be arranged on both sides of the feed rod.

[0018] Alternatively, if viewed in the thickness direction of the flange forming portion, the excess portion removed in the correction step is formed into a "C" shape and located at the front end of the flange forming portion.

[0019] Alternatively, if viewed in the thickness direction of the flange forming portion, the excess portion removed in the correction step is at both ends of the "C", and the width gradually narrows towards the end of the "C", with both ends of the "C" being pointed.

[0020] Another aspect of the invention is a stamped part comprising a high-strength material and including: a cap-shaped portion formed by a cross-sectional shape of a plane orthogonal to the length direction; and a flange portion, which, when viewed in the length direction of the cap-shaped portion, extends from one end of the cap shape to the other, along a direction intersecting the length direction of the cap-shaped portion at an angle close to right angle on the convex side of the cap-shaped portion, starting from one end of the length direction of the cap-shaped portion.

[0021] The dimension of the flange portion extending from the top plate portion of the cap-shaped portion is greater than the dimension of the depth of the cap-shaped portion.

[0022] [The effects of the invention]

[0023] According to the present invention, in the manufacturing method of the stamped part comprising a high-strength material and having a cap-shaped part and a flange part, the effect of processing can be achieved without cracking (fracture, cracking) during the forming process. Attached Figure Description

[0024] Figure 1 This is a diagram that schematically illustrates the steps in a method for manufacturing a stamped part according to an embodiment of the present invention.

[0025] Figure 2 (a) is a diagram showing the usage state of the stamped part according to an embodiment of the present invention, and (b) is an enlarged view of part IIB in (a).

[0026] Figure 3 This is a plan view showing the part obtained in the preparatory step of the method for manufacturing a stamped part according to an embodiment of the present invention.

[0027] Figure 4 This is a perspective view showing the part obtained in the first forming step of the method for manufacturing a stamped part according to an embodiment of the present invention.

[0028] Figure 5 yes Figure 4 The V-arrow view in the image.

[0029] Figure 6 yes Figure 4 The VI arrow view in the diagram.

[0030] Figure 7 It means Figure 6 The diagram shows section VII-VII.

[0031] Figure 8 This is a perspective view showing the part obtained in the second forming step of the method for manufacturing a stamped part according to an embodiment of the present invention.

[0032] Figure 9 yes Figure 8 The IX arrow view in the image.

[0033] Figure 10 yes Figure 8 The X-arrow view in the image.

[0034] Figure 11 It means Figure 10 The diagram shows the XI-XI section.

[0035] Figure 12 This is a perspective view showing the result obtained in a modified step of the method for manufacturing a stamped part according to an embodiment of the present invention.

[0036] Figure 13 yes Figure 12 The XIII arrow view in the image.

[0037] Figure 14 yes Figure 12 The XIV arrow view in the image.

[0038] Figure 15 It means Figure 14 The diagram shows the XV-XV section.

[0039] Figure 16 This is a perspective view of the stamped part 1 obtained in the flange forming step and subsequent steps of the manufacturing method of the stamped part according to an embodiment of the present invention.

[0040] Figure 17 yes Figure 16 The XVII arrow view in the image.

[0041] Figure 18 yes Figure 16 The XVIII arrow view in the image.

[0042] Figure 19 yes Figure 18 The arrow view of section XIX-XIX in the figure also represents the flange.

[0043] Figure 20 This diagram illustrates the operation of the stamped part in the flange forming step of the manufacturing method of the stamped part according to an embodiment of the present invention.

[0044] Figure 21 This diagram illustrates the bending at the boundary between the flange forming portion and the excess portion during the second forming step of the manufacturing method of the stamped part according to an embodiment of the present invention.

[0045] Figure 22 This is a diagram showing the stamping part and the die in the flange forming step of the method for manufacturing stamped parts according to an embodiment of the present invention.

[0046] Figure 23(a) is a diagram showing the surplus portion, etc., in the modification step of the manufacturing method of the stamped part according to the embodiment of the present invention, and (b) is a diagram showing the cross section XXIIIB-XXIIIB in (a).

[0047] Figure 24 This is a diagram illustrating the stress generation state in a stamped part according to an embodiment of the present invention.

[0048] Figure 25 This is a diagram showing the stress generation state in the stamped part of the comparative example.

[0049] [Explanation of Symbols]

[0050] 1: Stamped parts

[0051] 9: Cap-shaped part

[0052] 11: Flange section

[0053] 29: Flange Formation Location

[0054] 27: Surplus Position

[0055] 31: Boundary section

[0056] 29A: Central Department

[0057] 29B, 29C: Both ends

[0058] 35: Rod for forward feed machining

[0059] HA1: Flange unfolded height

[0060] HB1: Depth of the cap-shaped part. Detailed Implementation

[0061] The stamped part (stamped product) 1 according to the embodiments of the present invention is as follows: Figure 2 As shown, for example, a part that forms part of the frame 3 of a car or the like, such as a front roof bracket R / L. The front roof bracket R and the front roof bracket L are symmetrical in shape.

[0062] The front roof support and the front roof crossbeam 5 together form part of the vehicle body that fixes the front window glass and the roof. The two ends of the front roof crossbeam and the front roof support R / L (the stamped parts 1 at both ends) are connected to the front pillar 7, forming the main frame of the vehicle body.

[0063] Stamped part 1 is formed by stamping high-strength material (high-tensile steel) using dies or the like, such as... Figures 16-19 As shown, the stamped part 1 has a cap-shaped portion 9 and a flange portion 11. The flange portion 11 and a portion of the cap-shaped portion 9 are welded to the front pillar 7, for example.

[0064] For ease of explanation, we define a specific direction in space as the X direction, a specific direction orthogonal to the X direction as the Y direction, and a direction orthogonal to both the X and Y directions as the Z direction.

[0065] The cap-shaped portion 9 is formed by a cross-sectional shape created by a plane orthogonal to the length direction (Z direction).

[0066] The cap-shaped portion 9 will be further explained. Furthermore, since the stamped part 1 forms the frame 3, it is practically not a completely flat sheet, but rather a complex shape formed by appropriately connecting slightly curved plates. Therefore, the X, Y, and Z directions in the description of the stamped part 1 are not strictly defined and should be interpreted as approximate directions. Moreover, to avoid stress concentration, the curved portions of the plates in the stamped part 1 (such as the boundary between the cap-shaped portion 9 and the flange portion 11) or corners are rounded.

[0067] Cap-shaped part 9 Figure 19 As shown, it is composed of a top plate portion 13, a first side wall portion 15, a first bottom plate portion 17, a second side wall portion 19 and a second bottom plate portion 21.

[0068] In the top plate portion 13, the Y direction is the thickness direction, and it extends a specific length along the X direction. In the first side wall portion 15, the X direction is the thickness direction, and it extends a specific length along the Y direction from one end of the top plate portion 13 in the X direction. In the first bottom plate portion 17, the Y direction is the thickness direction, and it extends a specific length along the X direction and in a direction separate from the top plate portion 13, starting from the front end of the first side wall portion 15 in the Y direction (the end opposite to the top plate portion 13).

[0069] In the second side wall portion 19, the X direction is the thickness direction, and it extends a specific length from the other end of the top plate portion 13 in the X direction, along the Y direction and on the same side as the first side wall portion 15. In the second bottom plate portion 21, the Y direction is the thickness direction, and it extends a specific length from the front end of the second side wall portion 19 in the Y direction (the end opposite to the top plate portion 13), along the X direction and in a direction separate from the top plate portion 13.

[0070] Flange part 11 Figure 19 As shown, when viewed along the length direction (Z direction) of the cap-shaped portion 9, it is provided on the convex side of the cap-shaped portion 9 from one end to the other.

[0071] To elaborate further, when viewed in the Z direction, the flange portion 11 is roughly rectangular in shape, and in the X direction, it is provided from the front end of the first base plate portion 17 (the end opposite to the first side wall portion 15) to the front end of the second base plate portion 21 (the end opposite to the second side wall portion 19).

[0072] When observed in the Z direction, the flange portion 11 is disposed on one side of the cap-shaped portion 9 (the top plate portion 13, the first side wall portion 15, the first bottom plate portion 17, the second side wall portion 19, the second bottom plate portion 21) in the Y direction, and is disposed on the side where the top plate portion 13, the first side wall portion 15, and the second side wall portion 19 protrude from the first bottom plate portion 17 and the second bottom plate portion 21 (the convex portion side).

[0073] In addition, the flange portion 11 is continuous throughout the entire cap shape of the cap-shaped portion 9 on the convex portion side of the cap-shaped portion 9. In addition, the flange portion 11 extends from one end in the length direction of the cap-shaped portion 9 in a direction intersecting the length direction of the cap-shaped portion 9. Thus, when observed in the length direction (Z direction) of the cap-shaped portion 9, it can also be considered that the flange portion 11 is formed in a "匚" shape with a specific width dimension.

[0074] In addition, the flange portion 11 is as Figure 18 shown, etc., and extends from one end portion in the length direction (Z direction) of the cap-shaped portion 9 in a direction (substantially the Y direction) intersecting the length direction (Z direction) of the cap-shaped portion 9 at an angle close to a right angle. That is, the intersection angle θ1 between the cap-shaped portion 9 and the flange portion 11 becomes an angle of about 100°. This angle θ1 can be changed within the range of 90° to 120°.

[0075] The maximum value HA1 of the unfolding height HA of the flange portion 11 from the top plate portion 13 of the cap-shaped portion 9 is greater than the maximum value HB1 of the depth (height dimension) HB of the cap-shaped portion 9. The depth HB of the cap-shaped portion 9 gradually decreases from the end of the cap-shaped portion 9 (the end opposite to the flange portion 11) in the Z direction as it approaches the flange portion 11.

[0076] As Figure 19 shown, when observed in the Z direction, the values of the extending lengths of the first side wall portion 15, the first bottom plate portion 17, and the second bottom plate portion 21 are substantially equal to each other. The value of the extending length of the second side wall portion 19 is greater than the value of the extending length of the first side wall portion 15, and the value of the extending length of the top plate portion 13 is greater than the value of the extending length of the second side wall portion 19.

[0077] Furthermore, when observed in the Z direction, the bending angle of the first side wall portion 15 with respect to the top plate portion 13 is an obtuse angle close to 90°, and the bending angle of the second side wall portion 19 with respect to the top plate portion 13 is also an obtuse angle close to 90°. In addition, when observed in the Z direction, the bending angle of the first bottom plate portion 17 with respect to the first side wall portion 15 is also an obtuse angle close to 90°, and the bending angle of the second bottom plate portion 21 with respect to the second side wall portion 19 is also an obtuse angle close to 90°.

[0078] Furthermore, in the stamped part 1, a circular through hole 22 is provided near the flange portion 11 of the top plate portion 13. The through hole 22 is used when the stamped part 1 is welded to the front pillar 7 or other parts not shown. In addition, although the through hole 22 is formed by the first forming step, it can also be formed by other steps.

[0079] Next, the manufacturing method of stamped part 1 will be explained.

[0080] In the manufacturing of stamped part 1, for example, a mass production process using progressive (continuous feed) machining is employed. Additionally, coil material 25 made of high-strength material (see reference) is used. Figure 3 As a material, the method for manufacturing stamped part 1 first includes a preparatory step of obtaining a flat plate-shaped raw material 23 (see reference). Figure 1 (a) Figure 3 In the preparatory step, the unusable portion is pre-cut (removed) from the coil material 25 to obtain a raw material 23 of a specific shape. In the preparatory step, an excess portion 27 is provided at the location that becomes the flange portion 11 (see reference). Figure 21 , Figure 23 ).also, Figure 3 Reference symbol 49 in the middle represents the guide hole.

[0081] In the manufacturing method of stamped part 1, the preparatory step ( Figure 1 The raw material 23 obtained in (a)) in the first molding step ( Figure 1 (b)), the second molding step ( Figure 1 (c) Correction steps ( Figure 1 (d) and flange forming steps ( Figure 1 (e) Forming (e.g., stamping). Furthermore, subsequent steps are performed on the material obtained in the flange forming step ( Figure 1 (f)) and thus obtain stamped part 1.

[0082] Figure 1 (b) Figures 4 to 7 This refers to the semi-finished product 28 obtained in the first molding step. Figure 1 (c) Figures 8-11 This refers to the semi-finished product 28 obtained in the second molding step. Figure 1 (d) Figures 12-15 This refers to the semi-finished product 28 obtained in the correction step. Figure 1 (e) indicates the semi-finished product 28 obtained in the flange forming step. Figure 1 (f) Figures 16-19 This refers to stamped part 1 obtained in subsequent steps.

[0083] In the first molding step, such as Figure 7As shown, the flat material (raw material) 23 obtained in the preparatory step is shaped into a specific shape until the depth HC of the cap-shaped part 9 (the part that becomes the cap-shaped part 9) becomes the middle (halfway) depth.

[0084] In the second molding step, such as Figure 11 As shown, the material (semi-finished product) 28 formed in the first forming step is formed until the depth HD of the cap-shaped portion 9 (the part that becomes the cap-shaped portion 9) becomes the target depth (final depth; the depth of the stamped part 1). Furthermore, in the first forming step and the second forming step, there is an excess portion 27, and the portion that becomes the flange portion 11 and the excess portion 27 are deformed (formed) according to the forming of the cap-shaped portion 9 by stamping in the first forming step and the second forming step.

[0085] In the correction steps, such as Figure 12 , Figure 23 As shown, the excess portion 27, which is located on the outer periphery of the flange forming portion 29, and excluding the portion that becomes the cap-shaped portion 9, formed by the first molding step and the second molding step, is cut off and removed. The excess portion 27 exists on the opposite side of the cap-shaped portion 9 and on the outer periphery of the flange forming portion 29.

[0086] In the flange forming process, such as Figure 1 (e) Figure 16 As shown, after removing the excess portion 27 in the correction step, the flange forming portion 29 is bent to form the flange portion 11 in a direction that unfolds in a direction that intersects the length direction of the cap-shaped portion 9.

[0087] Furthermore, in the second molding step, such as Figure 21 , Figure 23 As shown in (b), a bend is made at the boundary 31 between the flange forming portion 29 and the excess portion 27 (see reference). Figure 21 (The arrow). That is, if it does not bend at the boundary 31, the surplus part 27 will be as shown. Figure 21 As shown by the solid line, the surplus portion 27 is formed by bending at the boundary 31. Figure 21 The two-point locking line is shown in the figure.

[0088] Additionally, in the flange forming process, such as Figure 22 As shown, the bending point of the central part 29A of the flange forming part 29 begins later than the bending point of the two ends 29B and 29C of the flange forming part 29.

[0089] That is, the central portion 29A of the flange forming portion 29 in the mold 33 is more recessed than the two ends 29B and 29C of the flange forming portion 29 in the mold 33. Moreover, when forming the flange portion 11, the two ends 29B and 29C of the flange forming portion 29 are formed first at the portions 33B and 33C of the mold 33, and then the central portion 29A of the flange forming portion 29 is formed at the portion 33A of the mold 33.

[0090] Furthermore, in order to first form the two ends 29B and 29C of the flange forming portion 29, and then form the central portion 29A of the flange forming portion 29, and as... Figure 20 As shown, between the correction step and the flange forming step, the semi-formed part 28 is rotated with the feed rod 35 (described in detail later) as the rotation center. Figure 20 The solid line indicates the position of the semi-molded part 28 before the flange forming step, while the two-point locking line indicates the position of the semi-molded part 28 after the flange forming step. By rotating the semi-molded part 28, the friction (friction force) on the flange forming part 29 is reduced when the mold 33 bends the flange forming part 29.

[0091] Furthermore, in the manufacturing method of the stamped part 1, the stamped part 1 is manufactured using a feed rod 35 (see reference) provided on the opposite side of the flange portion 11. Figure 1 , Figure 3 (etc.), formed by continuous stamping.

[0092] To elaborate further, after the preparatory steps are performed by Figure 3 When the coil material 25 shown is used to obtain raw material 23, it sequentially obtains a pair (2 of each). Figure 3 The raw materials 23A, 23B, and 23C are shown. That is, raw material 23, semi-finished product 28, and stamped part 1 are symmetrically arranged on both sides of the feed rod 35, separated by the feed rod 35. Furthermore, two stamped parts 1 can be obtained from each. Alternatively, it is not necessary to obtain... Figure 3 The raw materials 23Aa, 23Ba, and 23Ca on one side are shown, and one raw material 23A, one raw material 23B, and one raw material 23C are obtained in sequence.

[0093] In the manufacturing method of stamped part 1, a plurality of stamped parts, etc., which are to be stamped, are arranged on a feed rod 35 having a specific width and thickness and extending relatively long along the X direction. The stamped parts, etc., are materials (raw materials 23, semi-finished products 28) and stamped parts 1 that are to be formed in the preparatory step, the first forming step, the second forming step, the correction step, and the flange forming step.

[0094] If viewed in the thickness direction (Y direction) of the feed machining rod 35, then as Figure 3 As shown, a plurality of stamped parts are arranged on one side of the feed rod 35 in the width direction (Z direction). These stamped parts are slightly separated from the feed rod 35 and are arranged at specific intervals in the length direction (X direction) of the feed rod 35. The length direction of the cap-shaped portion 9 in the stamped parts is aligned with the width direction of the feed rod 35. In addition, the flange portion 11 (flange forming portion 29) in the stamped parts is located on the opposite side of the feed rod 35. Furthermore, the stamped parts are connected to the feed rod 35 by a thin connecting portion 37. In a subsequent step, the connecting portion 37 is removed, and the stamped part 1 is separated from the feed rod 35.

[0095] In continuous stamping, for multiple stamped parts, the processing of the first forming step, the processing of the second forming step, the processing of the correction step, and the processing of the flange forming step are carried out in sequence according to the arrangement order described above.

[0096] For example, along the feed rod in the longitudinal direction, there are 5 first stamping parts (raw materials) 23. These stamping parts are arranged in the order described above as first stamping part, second stamping part, third stamping part, fourth stamping part, and fifth stamping part.

[0097] In the first forming process, the first forming step is performed on the first stamped part, etc. In the second forming process, the five stamped parts, etc. are moved appropriately along the length direction of the feed rod, the second forming step is performed on the second stamped part, etc., and the first forming step is performed on the first stamped part, etc.

[0098] In the third forming process, the five stamping parts are moved further along the length of the feed rod, and the first forming step is performed on the third stamping part, the first forming step is performed on the second stamping part, and the second forming step is performed on the first stamping part.

[0099] In the fourth forming process, the five stamping parts are moved further along the length of the feed rod, and the first forming step is performed on the fourth stamping part, the first forming step is performed on the third stamping part, the second forming step is performed on the second stamping part, and the correction step is performed on the first stamping part.

[0100] In the fifth forming process, the five stamping parts are moved further along the length of the feed rod, and the fifth stamping part is formed in the first forming step, the fourth stamping part is formed in the first forming step, the third stamping part is formed in the second forming step, the second stamping part is formed in the correction step, and the first stamping part is formed in the flange forming step.

[0101] By continuing this process, stamped parts can be obtained in pairs, for example, two at a time. In addition, the raw material 23 obtained in the preparatory step is also formed into pairs of coil material 25.

[0102] If the flange forming portion 29 is viewed along its thickness direction, the excess portion 27 removed in the correction step is as follows: Figure 23 As shown, it is formed in the shape of a "C" and is located at the front end of the flange forming part 29, which surrounds the flange part 11. In addition, if the flange forming part 29 is viewed along its thickness direction, the excess part 27 removed in the correction step is at both ends of the "C", and the width gradually narrows towards the end of the "C", with the two ends of the "C" protruding.

[0103] According to the manufacturing method of stamped part 1, stamped part 1 is manufactured through a first forming step, a second forming step, a correction step and a flange forming step. Therefore, cracking (fracture, cracking) will not occur during the forming process, and stamped part 1 can be obtained.

[0104] That is, in the manufacturing method of the stamped part 1, since a large surplus of material is pre-secured in the part forming the flange portion 11 (due to the provision of the surplus portion 27), the stress generated during forming plays a role in dispersion. As a result, stress concentration at the part where cracking occurs during forming can be mitigated, and cracking on the stamped part 1 during forming can be suppressed.

[0105] Furthermore, while maintaining excess material (excess portion 27) in the outer direction of the flange portion 11, the cap-shaped portion 9 is formed in the second forming step, and the excess portion 27 is removed in the correction step. This alters the stress distribution during the forming of the flange portion 11, thereby suppressing cracking during the flange portion forming process.

[0106] That is, during the forming process, in Figure 24 The part indicated by reference symbol 39 will generate a certain degree of stress, but this stress will not cause the stamped part 1 to crack or otherwise.

[0107] Furthermore, since the cap-shaped part 9 is formed in two steps, the occurrence of cracking can be suppressed.

[0108] In contrast, if the cap-shaped part 9 and the flange part 11 are formed simultaneously using existing processes, then in Figure 25 The area indicated by reference symbol 41 will experience high stress, which may cause the stamped part 43 to crack. That is, it will... Figure 25 Edge cracking (cracking from the end of the material inward) occurs at the location indicated by part 41. To further explain, if the bottom plate parts 17 and 21 of the cap-shaped part 9 are formed by pressing (restricting) the upper part (top plate part) 13 of the cap-shaped part 9 using a welding pad (not shown) (deep drawing, increasing the height of the cap), stress as indicated by arrow A1 will be generated at the flange part 11 at the end.

[0109] Furthermore, if the step of bending the flange 11 into a regular shape is performed simultaneously, the stress indicated by arrow A2 will be generated at the front end of the flange 11. The stress indicated by arrow A1 is in the opposite direction to the stress indicated by arrow A2, and therefore will exceed the elongation limit of the material (semi-formed product) 28. Figure 25 An edge crack occurs at the location indicated by reference symbol 41 (the same crack will occur on the opposite side of the location indicated by reference symbol 41 in the X direction).

[0110] also, Figure 25 The stress value generated at the location indicated by reference symbol 45 is less than the stress value generated at the location indicated by reference symbol 41.

[0111] Furthermore, according to the manufacturing method of stamped part 1, since the material is bent at the boundary 31 between the flange forming portion 29 and the excess portion 27 in the second forming step (bending the material end), the material loss can be reduced. Figure 25 The value of the stress indicated by the middle arrow A1.

[0112] That is, while forming the cap-shaped portion (the portion that becomes cap-shaped portion 9 in stamped part 1) that has been shallowly formed in the first forming step until the cross-sectional shape of the cap becomes a regular (final) shape, the end of the flange forming portion 29 (the excess portion 27) is bent, so the stress generated in the cap cross-section by forming in the direction of the cap cross-section ( Figure 25 The stress indicated by the middle arrow A1 decreases.

[0113] To elaborate further, it is believed that by bending the material end (the end of the flange forming portion 29), the material rigidity at the material end is increased, the stress (tensile stress) at the material end is dispersed, and the possibility of cracking is suppressed. In addition, since the forming process includes the excess portion 27 in addition to the material required for the regular shape, there is also an effect of further dispersing stress.

[0114] Furthermore, in the manufacturing method of stamped part 1, during the flange forming step, the bending time of the central portion 29A of the flange forming part 29 begins later than the bending time of the two ends 29B and 29C of the flange forming part 29. That is, since the bending tool used to bend the flange forming part 29 near the crack initiation point is convex and the crack initiation point (central portion) is concave, the convex bending tool begins to bend the ends 29B and 29C of the flange forming part 29 before the concave bending tool, and then the central portion 29A of the flange begins to bend. By delaying the bending process of the central portion 29A of the flange forming part 29, the stress generated in the horizontal left-right direction is mitigated, thereby suppressing the occurrence of cracks.

[0115] To further explain, during the flange forming step, the bending punch of the die is designed to be concave in the center (protruding at both ends). When using this bending punch, the left and right ends first abut against the flange being bent (the workpiece) to begin the bending process. The bending of the flange's center begins later. As a result, the bending points at the left and right ends and the center of the flange are staggered, causing the stress in the center of the flange to expand horizontally to the left and right. Figure 25 The stress indicated by arrow A3 is relieved, thus preventing cracking.

[0116] Conversely, if the bending punch (in the horizontal direction) is straight (if the bending start points are not staggered), a stress A3 will be generated in the central portion 29A of the flange forming part 29, oriented in the horizontal left-right direction. That is, since the left and right portions (corners) 29B and 29C of the flange forming part 29 are continuous from the base plate portions 17 and 21 of the cap-shaped portion 9, therefore... Figure 25 The stresses indicated by the middle arrows A1 and A2 cause stress to be generated at the location indicated by reference symbol 47 in the flange forming part 29. Since the stress in part 47 is generated from left to right, it becomes a tensile stress along the horizontal direction at the central part 29A of the flange forming part 29, which becomes the main cause of cracking.

[0117] Furthermore, according to the manufacturing method of the stamped part 1, the stamped part 1 is formed by continuous stamping using a feed rod 35 provided on the opposite side of the flange 11, so even for the processing of high-strength materials (difficult-to-machine materials), the production efficiency is improved.

[0118] Furthermore, in the manufacturing method of the stamped part 1, the stamped part 1 is arranged on both sides of the feed rod 35. That is, the stamped part 1 is arranged on both sides across the feed rod 35, and feed processing can be performed, thus further improving production efficiency. In addition, since the stamped part 1 is arranged on both sides of the feed rod, force balance can be achieved, and the stamped part 1 can be formed with high efficiency.

[0119] Furthermore, according to the manufacturing method of the stamped part 1, if viewed in the thickness direction of the flange forming portion 29, the excess portion 27 removed in the correction step is formed into a "C" shape and located at the front end of the flange forming portion 29. Therefore, the amount of material used can be reduced as much as possible while preventing cracking and other occurrences during stamping.

Claims

1. A method for manufacturing a stamped part, the stamped part comprising a high-strength material and having: a cap-shaped portion formed by a cross-sectional shape of a plane orthogonal to the length direction; and a flange portion, which, when viewed in the length direction of the cap-shaped portion, extends from one end of the cap-shaped portion to the other end along a direction intersecting the length direction of the cap-shaped portion on the convex side of the cap-shaped portion, starting from one end of the length direction of the cap-shaped portion; The method for manufacturing the stamped part includes: In the first forming step, a flat, specific-shaped material is formed until the depth of the cap-shaped portion becomes the intermediate depth. The second molding step involves molding the material formed in the first molding step until the depth of the cap-shaped portion reaches the target depth. The correction step involves removing the excess portion on the outer periphery of the flange forming portion, excluding the cap-shaped portion formed in the first and second molding steps; and In the flange forming step, after removing the excess portion using the correction step, the flange forming portion is bent to form the flange portion in a direction that unfolds in a direction intersecting the length direction of the cap-shaped portion.

2. The method for manufacturing stamped parts according to claim 1, wherein, In the second forming step, the flange is bent at the boundary between the flange forming portion and the surplus portion.

3. The method for manufacturing stamped parts according to claim 1 or 2, wherein, In the flange forming step, the central part of the flange forming section begins to bend later than the two ends of the flange forming section begin to bend.

4. The method for manufacturing stamped parts according to claim 1 or 2, wherein, The stamped part is formed by continuous stamping using a feed rod located on the opposite side of the flange.

5. The method for manufacturing stamped parts according to claim 3, wherein, The stamped part is formed by continuous stamping using a feed rod located on the opposite side of the flange.

6. The method for manufacturing stamped parts according to claim 4, wherein, The stamped parts are arranged on both sides of the feed rod.

7. The method for manufacturing a stamped part according to claim 1 or 2, wherein, If viewed in the thickness direction of the flange forming portion, the excess portion removed in the correction step is formed in a "C" shape and is located at the front end of the flange forming portion.

8. The method for manufacturing stamped parts according to claim 3, wherein, If viewed in the thickness direction of the flange forming portion, the excess portion removed in the correction step is formed in a "C" shape and is located at the front end of the flange forming portion.

9. The method for manufacturing a stamped part according to claim 7, wherein, If viewed in the thickness direction of the flange forming portion, the excess portion removed in the correction step is at both ends of the "C" shape, and the width gradually narrows towards the end of the "C" shape, with both ends of the "C" shape being pointed.

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