JP7708722B2 - Manufacturing method of molded product and molded product - Google Patents

Description

This disclosure relates to a method for producing a molded article and the molded article.

In the drawing process of metal sheets, a reinforcing plate (i.e. a patch) is layered and welded to the base metal sheet to increase its strength, and then the sheet is pressed. In this type of processing, a difference in the elongation caused by pressing occurs between the reinforcing plate, which is located on the inside of the bend, and the base material, which is located on the outside. As a result, shear stress occurs in the welded part of the reinforcing plate, which may cause it to crack.

To address this issue, various countermeasures have been devised, such as providing holes in the reinforcing plate between the ridgeline of the bent portion and the welded portion, and providing the reinforcing plate with multiple notches aligned along the ridgeline of the bent portion (see Patent Documents 1 and 2).

JP 2020-121690 A Patent No. 4565756

When creating the above-mentioned holes in the reinforcing plate, the holes may not deform sufficiently, and stress may not be fully absorbed. Also, when creating the above-mentioned multiple notches in the reinforcing plate, stress relief may be insufficient depending on the press shape.

One aspect of the present disclosure aims to provide a method for manufacturing a molded product that can reduce stress concentration in the reinforcing plate.

One aspect of the present disclosure is a manufacturing method for a molded product, comprising a step of overlapping and welding a second metal plate to 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 bent portion connecting the first surface and the second surface and in which the second metal plate is overlapped are formed in 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.

With this configuration, the difference in elongation length between the first metal plate and the second metal plate at the bent portion is absorbed by the notch that overlaps with the bent portion. This reduces the concentration of stress, such as shear stress, in the second metal plate, which is the reinforcing plate.

In one aspect of the present disclosure, the welding step may form a first joint welded to a first region of the first metal plate that is a first surface of the first metal plate, and a second joint welded to a second region of the first metal plate that is a second surface of the first metal plate. At least one notch may extend along the plate surface of the second metal plate in a direction perpendicular to the ridge line to a position aligned with at least one of the first joint and the second joint. With this configuration, it is possible to suppress the transmission of shear stress from the bent portion to the first joint or the second joint. As a result, cracks in the first joint or the second joint are suppressed.

In one aspect of the present disclosure, at least one notch may overlap the bent portion over the entire width of the bent portion. This configuration promotes the effect of the notch in absorbing the difference in elongation length between the first metal plate and the second metal plate at the bent portion.

In one aspect of the present disclosure, the second metal plate may have at least one notch, that is, two notches facing each other in a direction parallel to the ridge line. With this configuration, 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 the concentration of stress, such as shear stress, in the second metal plate is promoted.

Another aspect of the present disclosure is a molded product comprising 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 that overlaps the bent portion.

With this configuration, when the first metal plate and the second metal plate are bent, the difference in the elongation length between the first metal plate and the second metal plate at the bent portion is absorbed by the notch that overlaps with the bent portion. This reduces the concentration of stress, such as shear stress, in the second metal plate, which is a reinforcing plate.

In one aspect of the present disclosure, the second metal plate may have a first joint welded to a first surface of the first metal plate and a second joint welded to a second surface of the first metal plate. At least one notch may extend along the plate surface of the second metal plate in a direction perpendicular to the ridge line to a position aligned with at least one of the first joint and the second joint. With this configuration, when the first metal plate and the second metal plate are bent, the transmission of shear stress from the bent portion to the first joint or the second joint can be suppressed. As a result, cracks in the first joint or the second joint are suppressed.

In one aspect of the present disclosure, at least one notch may overlap the bent portion over the entire width of the bent portion. This configuration promotes the effect of the notch in absorbing the difference in elongation length between the first metal plate and the second metal plate at the bent portion.

In one aspect of the present disclosure, the second metal plate may have at least one notch, that is, two notches facing each other in a direction parallel to the ridge line. With this configuration, when the first metal plate and the second metal plate are bent, the difference in the 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 the concentration of stress, such as shear stress, in the second metal plate is promoted.

FIG. 1A is a schematic perspective view of a molded article in an embodiment, and FIG. 1B is a schematic side view of the molded article of FIG. 1A. FIG. 2A is a schematic plan view of the blank after the welding process, and FIG. 2B is a schematic cross-sectional view taken along line IIB-IIB in FIG. 2A. 3A and 3B are schematic plan views of a blank piece according to an embodiment different from that of FIG. 2A. 4A and 4B are schematic perspective views of a molded product in an embodiment different from that in FIG. 1A. FIG. 5 is a flow diagram of a method for producing a molded product according to an embodiment. FIG. 6 is a schematic diagram showing an example of a bending step in the method for producing the molded product shown in FIG.

Hereinafter, embodiments to which the present disclosure is applied will be described with reference to the drawings.
[1. First embodiment]
[1-1. Configuration]
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 a press process.

The material of the first metal plate 2 and the second metal plate 3 is not particularly limited, and may be, for example, a steel plate. The first metal plate 2 and the second metal plate 3 may be made of different materials. The thickness of the first metal plate 2 and the second metal plate 3 is also not particularly limited, and the thickness of the first metal plate 2 and the thickness of the second metal plate 3 may be different.

The molded product 1 has a corner 10. The corner 10 is formed by, for example, pressing and squeezing the blank material in the thickness direction. The molded product 1 may have multiple corners 10. For example, the molded product 1 may be U-shaped or hat-shaped with two opposing side walls. The molded product 1 is used, for example, as a component part of an automobile body, such as a reinforcement, member, pillar, panel, etc.

<First metal plate>
The first metal plate 2 has a top wall 21, a side wall 22, a bent portion 23, and a flange 24. The plate surface of the top wall 21 and the plate surface of the side wall 22 intersect with each other.

The bent portion 23 is a portion between the top wall 21 and the side wall 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, which is continuous with the inner surface of the bent portion 23 among the plate surfaces of the top wall 21, and a second surface 22A, which is continuous with the inner surface of the bent portion 23 among the plate surfaces of the side wall 22. The second surface 22A intersects with the first surface 21A.

The flange 24 is formed by bending the end of the side wall 22 opposite the top wall 21 through bending processing of the first metal plate 2. The plate surface of the flange 24 intersects with the plate surface of the side wall 22.

<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 wall 22 and the bent portion 23 of the first metal plate 2.

Specifically, the second metal plate 3 overlaps the first surface 21A, the second surface 22A, and the inner surface of the bent portion 23 of the first metal plate 2. In other words, the second metal plate 3 is welded to the first metal plate 2 so as to overlap the bent portion 23 from the inside.

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. In other words, 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 significant.

As shown in Figures 2A and 2B, the second metal plate 3 has 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.

2A and 2B show a blank material (i.e., a sheet material before being bent into a molded product 1) in which a flat first metal plate 2 is welded to a flat second metal plate 3. The second metal plate 3 is bent together with the first metal plate 2 at a corner 10 of the molded product 1 by bending.

The first cover part 31 is a portion of the blank that is overlapped with the first region 21B that becomes the first surface 21A of the first metal plate 2. The second cover part 32 is a portion of the blank that is overlapped with the second region 22B that becomes the second surface 22A of the first metal plate 2.

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

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

The second joint 35 is a portion welded to the second region 22B (i.e., the second surface 22A) of the first metal plate 2. The second joint 35 is provided in the second cover portion 32 near an end of the first metal plate 2 in the width direction D1. The second joint 35 is provided in a position that sandwiches the bent portion 23 together with the first joint 34 in the longitudinal direction D2 of the first metal plate 2 (i.e., the direction perpendicular to the ridge line of the bent portion 23).

The third joint 36 is a portion welded to the first region 21B of the first metal plate 2. The third joint 36 is provided near the end of the first cover portion 31 opposite the first joint 34.

The fourth joint 37 is a portion welded to the second region 22B of the first metal plate 2. The fourth joint 37 is provided in the second cover portion 32 near the end opposite the second joint 35. The fourth joint 37 is provided in a position that sandwiches the bent portion 23 together with the third joint 36 in the longitudinal direction D2 of the first metal plate 2.

The first joint 34, the second joint 35, the third joint 36, and the fourth joint 37 are each formed, for example, by a nugget formed at a welding point of spot welding. Each joint may penetrate the first metal plate 2 or the second metal plate 3.

The first notch 38 extends from the end of the second metal plate 3 in the width direction D1 (i.e., the direction perpendicular to the ridge of the bent portion 23) in a direction parallel to the ridge of the bent portion 23. In other words, the first notch 38 is a portion where the end of the second metal plate 3 in the width direction D1 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.

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. The "width direction of the bent portion 23" is the direction perpendicular to the ridge line of the bent portion 23 on the plate surface of the second metal plate 3.

The maximum width of the first notch 38 is greater than the width of the bent portion 23. Furthermore, at least a portion of the boundary edge of the first notch 38 with the first cover portion 31 and the boundary edge of the first notch 38 with the second cover portion 32 are each located outside the bent portion 23 (i.e., in the area overlapping with the first surface 21A or the second surface 22A).

The first notch 38 extends along the plate surface of the second metal plate 3 in the longitudinal direction D2 of the first metal plate 2 to a position aligned with both the first joint 34 and the second joint 35. In other words, 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 with the first joint 34 and the second joint 35.

The second notch 39 extends from the end of the second metal plate 3 opposite the end where the first notch 38 is provided, in a direction parallel to the ridge 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.

The second notch 39 overlaps the bent portion 23. The first notch 38 and the second notch 39 face each other in the width direction D1 of the second metal plate 3, sandwiching the third cover portion 33 therebetween. The second notch 39 has a shape symmetrical to the first notch 38. The second notch 39 overlaps the bent portion 23 over the entire width direction of the bent portion 23.

The second notch 39 extends along the plate surface of the second metal plate 3 in the longitudinal direction D2 of the first metal plate 2 to a position aligned with both the third joint 36 and the fourth joint 37. In other words, 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 with the third joint 36 and the fourth joint 37.

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, such as the rectangular shape shown in FIG. 2A. The notches 38, 39 may also have a shape with an arc-shaped tip, as shown in FIG. 3A, or a triangular shape, as shown in FIG. 3B, in which the width decreases toward the inside of the second metal plate 3.

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

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

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

After the second metal plate 3 is overlapped, as shown in FIG. 2A, 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 by, for example, spot welding.

<Bending process>
In this process, the first metal plate 2 is bent together with the second metal plate 3 to obtain a molded product 1 having a corner 10 .

Specifically, the blank material obtained in the welding process S10 is hot-pressed (i.e., hot stamped) using a die 100 shown in FIG. 6 to form the corners 10. Depending on the materials of the first metal plate 2 and the second metal plate 3, the corners 10 may be formed by cold pressing.

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. In addition, the second metal plate 3 is bent along the top wall 21, the side wall 22, and the bent portion 23.

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

(1b) By extending the first notch 38 to a position aligned with the first joint 34 and the second joint 35, the transmission of shear stress from the bent portion 23 to the first joint 34 and the second joint 35 can be suppressed. As a result, cracks in the first joint 34 and the second joint 35 are suppressed.

(1c) The first notch 38 overlaps the bent portion 23 over the entire width of the bent portion 23, which promotes the first notch 38's ability to absorb the difference in elongation length between the first metal plate 2 and the second metal plate 3 at the bent portion 23.

(1d) The mutually opposing first notch 38 and second notch 39 can absorb the difference in elongation length 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 the concentration of stress such as shear stress in the second metal plate 3 is promoted.

2. Other embodiments
Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take various forms.

(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 and the second joint. The first notch may be aligned with only one of the first joint and the second joint. Also, the first notch does not have to be aligned with either the first joint or the second joint. The same applies to the relationship between the second notch and the third and fourth joints.

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

(2c) In the manufacturing method of the molded product of the above embodiment, the second metal plate does not necessarily have to have a second notch. In other words, the second metal plate may have only one notch that overlaps with the bent portion.

(2d) The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. In addition, part of the configuration of the above embodiments may be omitted. In addition, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. All aspects included in the technical idea identified from the wording of the claims are embodiments of the present disclosure.

DESCRIPTION OF SYMBOLS 1... Molded product, 2... First metal plate, 3... Second metal plate, 10... Corner, 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 portion, 33: third cover portion, 34: first joint portion, 35: second joint portion,
36... Third joint part, 37... Fourth joint part, 38... First notch, 39... Second notch,
100...mold.

Claims (8)

a step of overlapping and welding a second metal plate to the first metal plate;
bending the first metal plate together with the second metal plate;
Equipped with
In the bending step, a first surface, a second surface intersecting the first surface, and a bent portion connecting the first surface and the second surface and overlapping the second metal plate are formed in the first metal plate,
A method for manufacturing a molded product, wherein 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. A method for producing the molded article according to claim 1,
In the welding step, a first joint portion is formed in the second metal plate, the first joint portion being welded to a first region of the first metal plate that is the first surface, and a second joint portion is formed in the second region of the first metal plate that is the second surface,
A method for manufacturing a molded product, wherein the at least one notch extends along the plate surface of the second metal plate in a direction perpendicular to the ridge line to a position aligned with at least one of the first joint and the second joint. A method for producing the molded article according to claim 1 or 2, comprising the steps of:
A method for manufacturing a molded product, wherein the at least one notch overlaps the bent portion over the entire width direction of the bent portion. A method for producing the molded article according to claim 1 or 2, comprising the steps of:
A method for manufacturing a molded product, 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. 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;
a second metal plate welded to the first metal plate so as to overlap the bent portion of the first metal plate;
Equipped with
A molded product, wherein 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. The molded article according to claim 5,
The second metal plate is
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;
having
A molded product, wherein the at least one notch extends along the plate surface of the second metal plate in a direction perpendicular to the ridge line to a position aligned with at least one of the first joint portion and the second joint portion. The molded article according to claim 5 or claim 6,
The at least one notch overlaps the bent portion over the entire width of the bent portion. The molded article according to claim 5 or claim 6,
A molded product, 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.