Method for manufacturing a molded article and molded article

Abstract

To provide a production method of a molded item which enables reduction of stress concentration in a reinforcement plate.SOLUTION: One aspect of the disclosure includes: a step in which a first metallic plate and a second metallic plate are overlapped to be welded; and a step in which the first metallic plate and the second metallic plate are bent. In the bending step, a first surface, a second surface intersecting with the first surface, and a bending part which connects the first surface with the second surface and is overlapped with the second metallic plate are formed at the first metallic plate. The second metallic plate has at least one cutout which extends from an end of the second metallic plate in a direction parallel to a ridge line of the bending part and overlaps with the bending part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a molded product and a molded product.

Background Art

[0002] In the drawing process of a metal plate, in order to increase the strength, a reinforcing plate (that is, a patch) is lap-welded to the base material of the metal plate, and then pressing is performed. In such a process, a difference in elongation length due to pressing occurs between the reinforcing plate disposed on the inner side of the bend and the base material disposed on the outer side. As a result, shear stress is generated at the welded portion of the reinforcing plate, and there is a risk of cracking.

[0003] Therefore, countermeasures such as a method of providing a hole in the reinforcing plate disposed between the ridge line of the bent portion and the welded portion, and a method of providing a plurality of notches arranged along the ridge line of the bent portion in the reinforcing plate have been devised (see Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the method of providing the above-described hole in the reinforcing plate, deformation of the hole may be insufficient, and there is a possibility that stress cannot be sufficiently absorbed. Further, in the method of providing the above-described plurality of notches in the reinforcing plate, stress relaxation may be insufficient depending on the press shape.

[0006] One aspect of the present disclosure aims to provide a method for manufacturing a molded product capable of reducing stress concentration in a reinforcing plate.

Means for Solving the Problems

[0007] One aspect of the present disclosure is a method for manufacturing a molded product, which includes a step of overlapping and welding a second metal plate on a first metal plate, and a step of bending the first metal plate together with the second metal plate. In the bending step, a first surface, a second surface intersecting the first surface, and a bending portion connecting the first surface and the second surface and having the second metal plate overlapped thereon are formed on the first metal plate. The second metal plate extends from an end of the second metal plate in a direction parallel to the ridge line of the bending portion and has at least one notch overlapping the bending portion.

[0008] According to such a configuration, the difference in elongation lengths between the first metal plate and the second metal plate in the bending portion is absorbed by the notch overlapping the bending portion. Therefore, stress concentration such as shear stress in the second metal plate, which is a reinforcing plate, can be reduced.

[0009] In one aspect of the present disclosure, in the welding step, a first joint portion welded to a first region that becomes the first surface of the first metal plate and a second joint portion welded to a second region that becomes the second surface of the first metal plate may be formed on the second metal plate. The at least one notch may extend along the plate surface of the second metal plate to a position aligned with at least one of the first joint portion and the second joint portion in a direction orthogonal to the ridge line. According to such a configuration, transmission of shear stress from the bending portion to the first joint portion or the second joint portion can be suppressed. As a result, cracking at the first joint portion or the second joint portion is suppressed.

[0010] In one aspect of the present disclosure, the at least one notch may overlap the bending portion across the entire width direction of the bending portion. According to such a configuration, the effect of absorbing the difference in elongation lengths between the first metal plate and the second metal plate in the bending portion by the notch is promoted.

[0011] In one aspect of the present disclosure, the second metal plate may have two notches facing each other in a direction parallel to the ridge line as the at least one notch. According to such a configuration, the difference in elongation lengths between the first metal plate and the second metal plate can be absorbed on both sides of the second metal plate. As a result, the effect of reducing stress concentration such as shear stress in the second metal plate is promoted.

[0012] Another aspect of the present disclosure is a molded product including a first metal plate having a first surface, a second surface intersecting the first surface, and a bent portion connecting the first surface and the second surface, and a second metal plate welded to the first metal plate so as to overlap the bent portion of the first metal plate. The second metal plate extends from an end of the second metal plate in a direction parallel to the ridge line of the bent portion and has at least one notch overlapping the bent portion.

[0013] According to such a configuration, when the first metal plate and the second metal plate are bent, the difference in elongation length between the first metal plate and the second metal plate in the bent portion is absorbed by the notch overlapping the bent portion. Therefore, stress concentration such as shear stress in the second metal plate, which is a reinforcing plate, can be reduced.

[0014] In one aspect of the present disclosure, the second metal plate may have a first joint welded to the first surface of the first metal plate and a second joint welded to the second surface of the first metal plate. The at least one notch may extend along the plate surface of the second metal plate to a position aligned with at least one of the first joint and the second joint in a direction orthogonal to the ridge line. According to such a configuration, when the first metal plate and the second metal plate are bent, transmission of shear stress from the bent portion to the first joint or the second joint can be suppressed. As a result, cracking at the first joint or the second joint is suppressed.

[0015] In one aspect of the present disclosure, the at least one notch may overlap the bent portion across the entire width direction of the bent portion. According to such a configuration, the absorption effect of the difference in elongation length between the first metal plate and the second metal plate in the bent portion by the notch is promoted.

[0016] In one aspect of the present disclosure, the second metal plate may have two notches facing each other in a direction parallel to the ridge line as the at least one notch. According to such a configuration, when the first metal plate and the second metal plate are bent, the difference in elongation length between the first metal plate and the second metal plate can be absorbed on both sides of the second metal plate. As a result, the effect of reducing stress concentration such as shear stress in the second metal plate is promoted.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

MODE FOR CARRYING OUT THE INVENTION

[0018] Hereinafter, embodiments to which the present disclosure is applied will be described with reference to the drawings. [1. First Embodiment] [1-1. Configuration] The molded product 1 shown in Figures 1A and 1B is formed by bending a blank material in which a first metal plate 2 and a second metal plate 3 are overlapped. The bending process includes press working.

[0019] The materials of the first metal plate 2 and the second metal plate 3 are not particularly limited, and for example, they are made of steel plates. Also, the first metal plate 2 and the second metal plate 3 may be made of different materials. The thicknesses of the first metal plate 2 and the second metal plate 3 are not particularly limited, and the thickness of the first metal plate 2 and the thickness of the second metal plate 3 may be different.

[0020] The molded product 1 has a corner portion 10. The corner portion 10 is formed by, for example, pressing and squeezing a blank material in the thickness direction. Note that the molded product 1 may have a plurality of corner portions 10. For example, the molded product 1 may have a U-shape or a hat-shape having two opposing side walls. The molded product 1 is used, for example, as a component of an automobile body such as a reinforcement, a member, a pillar, or a panel.

[0021] <First metal plate> The first metal plate 2 has a top wall 21, side walls 22, a bent portion 23, and a flange 24. The plate surface of the top wall 21 intersects with the plate surfaces of the side walls 22.

[0022] The bent portion 23 is a portion between the top wall 21 and the side walls 22 and is bent by bending the first metal plate 2. The bent portion 23 constitutes the corner portion 10 of the molded product 1. The bent portion 23 connects a first surface 21A that is continuous with the inner surface of the bent portion 23 on the plate surface of the top wall 21 and a second surface 22A that is continuous with the inner surface of the bent portion 23 on the plate surface of the side wall 22. The second surface 22A intersects with the first surface 21A.

[0023] The flange 24 is formed by bending the end portion of the side wall 22 on the side opposite to the top wall 21 by bending the first metal plate 2. The plate surface of the flange 24 intersects with the plate surface of the side wall 22.

[0024] <Second metal plate> The second metal plate 3 is overlapped and welded to the first metal plate 2. The second metal plate 3 is disposed across the top wall 21, the side walls 22, and the bent portion 23 of the first metal plate 2.

[0025] Specifically, the second metal plate 3 is overlapped with the first surface 21A of the first metal plate 2, the second surface 22A, and the inner surface of the bent portion 23. That is, the second metal plate 3 is welded to the first metal plate 2 so as to overlap the bent portion 23 from the inside.

[0026] The second metal plate 3 may be welded to the first metal plate 2 so as to overlap the bent portion 23 from the outside. That is, the second metal plate 3 may be overlapped on the outer surface of the bent portion 23. However, when the second metal plate 3 is overlapped from the inside of the bent portion 23, the effect of reducing stress concentration in the second metal plate 3 becomes remarkable.

[0027] As shown in FIGS. 2A and 2B, the second metal plate 3 includes a first cover portion 31, a second cover portion 32, a third cover portion 33, a first joint portion 34, a second joint portion 35, a third joint portion 36, a fourth joint portion 37, a first notch 38, and a second notch 39.

[0028] Note that FIGS. 2A and 2B illustrate a blank material (that is, a plate material before being bent into the molded product 1) in which the flat second metal plate 3 is welded to the flat first metal plate 2. The second metal plate 3 is bent together with the first metal plate 2 by bending at the corner portion 10 of the molded product 1.

[0029] The first cover portion 31 is a portion overlapped on a first region 21B that becomes the first surface 21A of the first metal plate 2 in the blank material. The second cover portion 32 is a portion overlapped on a second region 22B that becomes the second surface 22A of the first metal plate 2 in the blank material.

[0030] The third cover portion 33 is a portion overlapped on the bent portion 23 of the first metal plate 2 and connects the first cover portion 31 and the second cover portion 32. The third cover portion 33, together with the bent portion 23 of the first metal plate 2, constitutes the corner portion 10 of the molded product 1.

[0031] The first joint portion 34 is a portion welded to the first region 21B (that is, the first surface 21A) of the first metal plate 2. The first joint portion 34 is provided in the first cover portion 31 near an end portion in the width direction D1 of the first metal plate 2 (that is, a direction parallel to the ridge line of the bent portion 23).

[0032] The second joint portion 35 is a portion welded to the second region 22B (that is, the second surface 22A) of the first metal plate 2. The second joint portion 35 is provided in the second cover portion 32 in the vicinity of the end portion in the width direction D1 of the first metal plate 2. The second joint portion 35 is provided at a position sandwiching the bent portion 23 together with the first joint portion 34 in the longitudinal direction D2 of the first metal plate 2 (that is, the direction orthogonal to the ridge line of the bent portion 23).

[0033] The third joint portion 36 is a portion welded to the first region 21B of the first metal plate 2. The third joint portion 36 is provided in the first cover portion 31 in the vicinity of the end portion on the side opposite to the first joint portion 34.

[0034] The fourth joint portion 37 is a portion welded to the second region 22B of the first metal plate 2. The fourth joint portion 37 is provided in the second cover portion 32 in the vicinity of the end portion on the side opposite to the second joint portion 35. The fourth joint portion 37 is provided at a position sandwiching the bent portion 23 together with the third joint portion 36 in the longitudinal direction D2 of the first metal plate 2.

[0035] The first joint portion 34, the second joint portion 35, the third joint portion 36, and the fourth joint portion 37 are each composed of, for example, nuggets formed at the welding points of spot welding. Note that each joint portion may penetrate the first metal plate 2 or the second metal plate 3.

[0036] The first notch 38 extends from the end portion in the width direction D1 of the second metal plate 3 (that is, the direction orthogonal to the ridge line of the bent portion 23) in a direction parallel to the ridge line of the bent portion 23. That is, the first notch 38 is a portion where the end portion in the width direction D1 of the second metal plate 3 is recessed inward. The first notch 38 is disposed between the first cover portion 31 and the second cover portion 32 in the longitudinal direction D2 of the first metal plate 2.

[0037] The first notch 38 overlaps the bent portion 23. Specifically, the first notch 38 overlaps the bent portion 23 over the entire width direction of the bent portion 23. Note that the "width direction of the bent portion 23" is the direction orthogonal to the ridge line of the bent portion 23 on the plate surface of the second metal plate 3.

[0038] The maximum width of the first notch 38 is larger than the width of the bent portion 23. Also, at least a part of the boundary edge of the first notch 38 with the first cover portion 31 and the boundary edge with the second cover portion 32 are each located outside the bent portion 23 (that is, in a region overlapping the first surface 21A or the second surface 22A).

[0039] The first notch 38 extends in the longitudinal direction D2 of the first metal plate 2 to a position aligned with both the first joint portion 34 and the second joint portion 35 along the plate surface of the second metal plate 3. That is, in the state of the blank material before bending, the first notch 38 extends in the longitudinal direction D2 of the first metal plate 2 to a position overlapping the first joint portion 34 and the second joint portion 35.

[0040] The second notch 39 extends from the end portion of the second metal plate 3 opposite to the end portion where the first notch 38 is provided in a direction parallel to the ridge line of the bent portion 23. The second notch 39 is disposed between the first cover portion 31 and the second cover portion 32 in the longitudinal direction D2 of the first metal plate 2.

[0041] The second notch 39 overlaps the bent portion 23. The first notch 38 and the second notch 39 face each other with the third cover portion 33 interposed therebetween in the width direction D1 of the second metal plate 3. Also, the second notch 39 has a shape symmetric to the first notch 38. The second notch 39 overlaps the bent portion 23 over the entire width direction of the bent portion 23.

[0042] The second notch 39 extends in the longitudinal direction D2 of the first metal plate 2 to a position aligned with both the third joint portion 36 and the fourth joint portion 37 along the plate surface of the second metal plate 3. That is, in the state of the blank material before bending, the second notch 39 extends in the longitudinal direction D2 of the first metal plate 2 to a position overlapping the third joint portion 36 and the fourth joint portion 37.

[0043] The planar shapes of the first notch 38 and the second notch 39 are not particularly limited. For example, the notches 38, 39 may have a constant width like the rectangular shape shown in FIG. 2A. Further, the notches 38, 39 may have a shape with an arcuate tip as shown in FIG. 3A, or may have a width that decreases toward the inside of the second metal plate 3 like the triangular shape shown in FIG. 3B.

[0044] As shown in FIG. 4A, the first notch 38 and the second notch 39 may each extend inward beyond the joints 34, 35, 36, 37 in the width direction D1 of the first metal plate 2. Further, as shown in FIG. 4B, the joints 34, 35, 36, 37 may be provided at positions away from the ends in the width direction D1 of the first metal plate 2.

[0045] [1-2. Manufacturing method] The manufacturing method of the molded product shown in FIG. 5 is a method for manufacturing the molded product 1 of FIG. 1. The manufacturing method of the molded product of the present embodiment includes a welding step S10 and a bending step S20.

[0046] <Welding step> In this step, the second metal plate 3 is overlapped on the first metal plate 2 and welded. Specifically, the second metal plate 3 is overlapped so as to straddle the portion that becomes the top wall 21, the portion that becomes the side wall 22, and the portion that becomes the bent portion 23 of the first metal plate 2 before bending.

[0047] After overlapping the second metal plate 3, as shown in FIG. 2A, for example, by spot welding, the first joint 34, the second joint 35, the third joint 36, and the fourth joint 37 are formed on the second metal plate 3.

[0048] <Bending step> In this step, the first metal plate 2 is bent together with the second metal plate 3 to obtain the molded product 1 having the corner portion 10.

[0049] Specifically, for the blank material obtained in the welding step S10, the corner portion 10 is formed by hot pressing (i.e., hot stamping) using the mold 100 shown in FIG. 6. Note that depending on the materials of the first metal plate 2 and the second metal plate 3, the corner portion 10 may be formed by cold pressing.

[0050] As a result, the first metal plate 2 is drawn, and the top wall 21 (i.e., the first surface 21A), the side wall 22 (i.e., the second surface 22A), the bent portion 23, and the flange 24 are formed on the first metal plate 2. Further, the second metal plate 3 is bent along the top wall 21, the side wall 22, and the bent portion 23.

[0051] [1-3. Effects] According to the embodiment described in detail above, the following effects can be obtained. (1a) The difference in elongation lengths between the first metal plate 2 and the second metal plate 3 in the bent portion 23 is absorbed by the first notch 38 overlapping the bent portion 23. Therefore, stress concentration such as shear stress in the second metal plate 3, which is a reinforcing plate, can be reduced.

[0052] (1b) By extending the first notch 38 to a position aligned with the first joint portion 34 and the second joint portion 35, the transmission of shear stress from the bent portion 23 to the first joint portion 34 and the second joint portion 35 can be suppressed. As a result, cracking at the first joint portion 34 and the second joint portion 35 is suppressed.

[0053] (1c) Since the first notch 38 overlaps the bent portion 23 over the entire width direction of the bent portion 23, the effect of absorbing the difference in elongation lengths between the first metal plate 2 and the second metal plate 3 in the bent portion 23 by the first notch 38 is promoted.

[0054] (1d) The first notch 38 and the second notch 39 facing each other can absorb the difference in elongation lengths between the first metal plate 2 and the second metal plate 3 on both sides of the second metal plate 3. As a result, the effect of reducing stress concentration such as shear stress in the second metal plate 3 is promoted.

[0055] [2. Other Embodiments] As described above, the embodiments of the present disclosure have been explained. Needless to say, the present disclosure can take various forms without being limited to the above embodiments.

[0056] (2a) In the molded product of the above embodiment, the first notch does not necessarily have to extend to a position aligned with both the first joint portion and the second joint portion. The first notch may be aligned with only one of the first joint portion and the second joint portion. Further, the first notch does not have to be aligned with either the first joint portion or the second joint portion. The same applies to the relationship between the second notch and the third joint portion and the fourth joint portion.

[0057] (2b) In the method for manufacturing the molded product of the above embodiment, the first notch and the second notch do not necessarily have to overlap the bent portion over the entire width direction of the bent portion. For example, the widths of the first notch and the second notch may be smaller than the width of the bent portion.

[0058] (2c) In the method for manufacturing the molded product of the above embodiment, the second metal plate does not necessarily have to have the second notch. That is, there may be one notch overlapping the bent portion in the second metal plate.

[0059] (2d) The functions of one component in the above embodiment may be distributed among a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, a part of the configuration of the above embodiment may be omitted. Further, at least a part of the configuration of the above embodiment may be added to, replaced with, etc., the configuration of another of the above embodiments. Note that all aspects included in the technical idea specified from the language described in the claims are embodiments of the present disclosure.

Description of Reference Numerals

[0060] 1... Molded product, 2... First metal plate, 3... Second metal plate, 10... Corner portion, 21... Top wall, 21A... First surface, 21B... First region, 22... Side wall, 22A... Second surface, 22B... Second region, 23... Bent portion, 24... Flange, 31... First cover portion, 32…Second cover part, 33…Third cover part, 34…First joint part, 35…Second joint part, 36…Third joint part, 37…Fourth joint part, 38…First notch, 39…Second notch, 100…Mold.

Claims

1. A step of overlapping and welding a second metal plate on a first metal plate; A step of bending the first metal plate together with the second metal plate; Comprising: In the bending step, a first surface, a second surface intersecting with the first surface, and a bent portion connecting the first surface and the second surface and having the second metal plate overlapped thereon are formed on the first metal plate; The second metal plate extends from an end of the second metal plate in a direction parallel to a ridge line of the bent portion and has at least one notch overlapping the bent portion, a method for manufacturing a molded product.

2. A method for manufacturing a molded product according to Claim 1, wherein: In the welding step, a first joint portion welded to a first region that becomes the first surface of the first metal plate and a second joint portion welded to a second region that becomes the second surface of the first metal plate are formed on the second metal plate; The at least one notch extends to a position aligned with at least one of the first joint portion and the second joint portion along a plate surface of the second metal plate in a direction orthogonal to the ridge line, a method for manufacturing a molded product.

3. A method for manufacturing a molded product according to Claim 1 or Claim 2, wherein: The at least one notch overlaps the bent portion over the entire width direction of the bent portion, a method for manufacturing a molded product.

4. A method for manufacturing a molded product according to Claim 1 or Claim 2, wherein: The second metal plate has two notches facing each other in a direction parallel to the ridge line as the at least one notch, a method for manufacturing a molded product.

5. A first metal plate having a first surface, a second surface intersecting with the first surface, and a bent portion connecting the first surface and the second surface; A second metal plate welded to the first metal plate so as to overlap the bent portion of the first metal plate; Comprising: The second metal plate extends from an end of the second metal plate in a direction parallel to a ridge line of the bent portion and has at least one notch overlapping the bent portion, a molded product.

6. A molded product according to Claim 5, wherein: The second metal plate has: A first joint portion welded to the first surface of the first metal plate; A second joint portion welded to the second surface of the first metal plate; And has: The at least one notch extends to a position aligned with at least one of the first joint portion and the second joint portion along a plate surface of the second metal plate in a direction orthogonal to the ridge line, a molded product.

7. A molded product according to Claim 5 or Claim 6, wherein: The at least one notch is a molded article that overlaps the bent portion across the entire width direction of the bent portion.

8. The molded article according to claim 5 or claim 6, wherein the second metal plate has, as the at least one notch, two notches facing each other in a direction parallel to the ridge line.

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