METHOD OF MANUFACTURING FORMED PRODUCT

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Patent Application No. 2024-074376 filed on May 1, 2024 with the Japan Patent Office, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

The present disclosure relates to a method of manufacturing a formed product.

For example, Japanese Unexamined Patent Application Publication No. 2002-192247 discloses a technique for obtaining a formed product by pressing plate members placed on each other.

SUMMARY

As in the technique of the aforementioned Document, in a case where a formed product having a top plate portion and a vertical wall portion is obtained by pressing plate members placed on each other, there has been a problem that a gap between each of the plate members are likely to occur due to springback in which a bent material deforms in a direction of returning to its original shape. If the gap between each of the plate members increases after the pressing, it may cause inconvenience in subsequent operations, such as welding or assembling.

One aspect of the present disclosure is, in a method of manufacturing a formed product having a top plate portion and a vertical wall portion by pressing plate members placed on each other, to allow reduction in an amount of springback of the plate members during the pressing.

One mode of the present disclosure is a method of manufacturing a formed product having a top plate portion and a vertical wall portion by pressing plate members placed on each other. In the method of manufacturing the formed product, the plate members comprise a first member and a second member.

The first member includes a first top plate corresponding portion, a first vertical wall corresponding portion, and an extending portion. The first top plate corresponding portion corresponds to one part of the top plate portion of the formed product. The first vertical wall corresponding portion corresponds to at least one part of the vertical wall portion of the formed product. The second member includes a second top plate corresponding portion, and a second vertical wall corresponding portion. The second top plate corresponding portion corresponds to an other part of the top plate portion of the formed product. The second vertical wall corresponding portion corresponds to at least an other part of the vertical wall portion of the formed product. The second top plate corresponding portion of the second member is placed on the first member.

In any planes parallel to the plate members, a downstream side in a direction in a plan view from the first vertical wall corresponding portion and the second vertical wall corresponding portion toward the first top plate corresponding portion and the second top plate corresponding portion is referred to as an inner side, and a downstream side in a direction in a plan view from the first vertical wall corresponding portion and the second vertical wall corresponding portion toward a side opposite to the first top plate corresponding portion and the second top plate corresponding portion is referred to as an outer side. Furthermore, an end portion of the first member on the outer side is referred to as a first end, and an end portion of the second member on the outer side is referred to as a second end. The first end is located on the outer side with respect to the second end. The extending portion is a region of the first member from the first end to a portion of the first member on which the second end is placed.

A direction from the first member toward the second member is referred to as a moving direction. In the method, joining the first member and the second member to each other is performed by welding the first top plate corresponding portion and the second top plate corresponding portion to each other in a state where the first member is placed on the second member to include the extending portion. Furthermore, curving the first vertical wall corresponding portion, the second vertical wall corresponding portion, and the extending portion of the plate members toward the moving direction is performed by moving a metal press mold in the moving direction in a state where the first top plate corresponding portion and the second top plate corresponding portion after the joining are clamped to thereby make the metal press mold contact the extending portion.

In addition, forming the top plate portion and the vertical wall portion is performed by further moving the metal press mold in the moving direction in a state where the first vertical wall corresponding portion, the second vertical wall corresponding portion, and the extending portion are curved by the metal press mold to thereby press the first vertical wall corresponding portion and the second vertical wall corresponding portion of the plate members by the metal press mold.

In such a method of manufacturing, the top plate portion and the vertical wall portion can be formed after the metal press mold is made to contact the extending portion to curve the plate members. In other words, the top plate portion and the vertical wall portion are formed after the plate members are slightly curved. Therefore, it is possible to reduce springback of the vertical wall portion.

In one mode of the present disclosure, the metal press mold may comprise a vertical wall-forming portion and a shoulder portion. The vertical wall-forming portion is a portion for forming the vertical wall portion. The shoulder portion contacts blank materials (that is, the first member and the second member) at first among portions of the metal press mold. The shoulder portion is located on a downstream side in the moving direction with respect to an end of the vertical wall-forming portion on the downstream side in the moving direction and includes a surface on the outer side with respect to the vertical wall-forming portion whose angle to the moving direction is greater than an angle of the vertical wall portion to the moving direction. In the curving, the second end may be disposed on the inner side with respect to the shoulder portion, and the first vertical wall corresponding portion, the second vertical wall corresponding portion, and the extending portion of the plate members may be curved toward the moving direction by the shoulder portion contacting the extending portion.

In such a method of manufacturing, a configuration can be achieved in which the plate members are curved by the shoulder portion contacting the extending portion. In addition, by appropriately setting a shape of the shoulder portion, the degree to which the first member and the second member are curved can be effectively set.

In one mode of the present disclosure, the metal press mold may have a step shape having surfaces substantially parallel to the top plate portion. In this case, the metal press mold may comprise a first surface and a second surface as the surfaces. The first surface is located on an upstream side in the moving direction. The second surface is located on the downstream side in the moving direction. In the curving, the first vertical wall corresponding portion, the second vertical wall corresponding portion, and the extending portion of the plate members may be curved toward the moving direction by the second surface contacting the extending portion. In the forming of the top plate portion and the vertical wall portion, a flange portion that extends toward the outer side from the vertical wall portion may be formed by the first surface contacting the extending portion.

In such a method of manufacturing, also at in a case of manufacturing the formed product having the flange portion, it is possible to form the top plate portion and the vertical wall portion after the plate members are curved.

In one mode of the present disclosure, in the forming of the top plate portion and the vertical wall portion, the forming of the flange portion may be completed on the inner side with respect to the shoulder portion. It should be noted that the forming of the flange portion may be started while the shoulder portion coming into contact with the flange portion and then completed on the inner side with respect to the shoulder portion.

In such a method of manufacturing, it is possible to make the shoulder portion contact the plate members from further outer side, and thus it is possible to form the top plate portion, the vertical wall portion and the flange portion after the plate members are sufficiently curved.

In one mode of the present disclosure, a plate thickness of the second member is equal to or greater than a plate thickness of the first member.

In such a method of manufacturing, a second moment of area of the first member is likely to be equal to or smaller than a second moment of area of the second member, and thus the effect of curving the first member is more likely to be obtained. As a result, it is possible to reduce the springback of the first member and to reduce the gap between the first member and the second member.

In one mode of the present disclosure, the first member and the second member may be welded to each other in the vertical wall portion after the top plate portion and the vertical wall portion are formed.

In such a method of manufacturing, since the springback of the vertical wall portion is reduced, the gap between the first member and the second member becomes smaller. Therefore, welding operation can be performed effectively.

In one mode of the present disclosure, the formed product may be an automobile part. In such a method of manufacturing, it is possible to effectively manufacture the formed product to be applied to the automobile part.

BRIEF DESCRIPTION OF THE DRAWINGS

An example embodiment of the present disclosure will be described hereinafter with reference to the accompanying drawings, in which:

FIG. 1A is a perspective view of one example of a formed product;

FIG. 1B is a cross-sectional view of the formed product;

FIG. 2A is a cross-sectional view of a press-forming device and plate members before press-forming in a method of manufacturing the formed product;

FIG. 2B is a cross-sectional view of the press-forming device and the plate members in a state where a top plate portion is held;

FIG. 3 is a flow chart showing the method of manufacturing the formed product;

FIG. 4A is a plan view showing the plate members before the press-forming;

FIG. 4B is a cross-sectional view of the plate members before the press-forming;

FIG. 5A is a cross-sectional view of the press-forming device and the plate members in a state where the plate members are curved in the method of manufacturing the formed product;

FIG. 5B is a cross-sectional view of the press-forming device and the plate members in a state where the press-forming is completed;

FIG. 6A is a cross-sectional view of a press-forming device of a first modified example before press-forming;

FIG. 6B is a cross-sectional view of the press-forming device of the first modified example after the press-forming;

FIG. 7A is a cross-sectional view of a press-forming device of a second modified example before press-forming; and

FIG. 7B is a cross-sectional view of the press-forming device of the second modified example after the press-forming.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

1. Embodiment

[1-1. Configuration of Formed Product]

[Overview of Formed Product]

A formed product 1 shown in FIGS. 1A and 1B is a press-formed product obtained by pressing plate members placed on each other. The formed product 1 is used for, for example, an automobile part, such as a front pillar, a rocker, and a center-pillar, or other automobile component part, such as a pillar portion, and a frame portion of an automobile. The formed product 1 and a method of manufacturing the formed product 1 can be applied not only to an automobile component part but also to various other parts or products.

The formed product 1 is obtained by performing press-forming including bending on a first member 10 and a second member 20 each made of a steel plate. Each of the first member 10 and the second member 20 before the press-forming is, for example, a blank material obtained by cutting out a portion from a rolled steel plate. In one example, each of the first member 10 and the second member 20 is made of a cold-rolled steel plate, a hot-rolled steel plate, or an alloyed zinc-coated steel plate. In the present embodiment, an alloyed zinc-coated steel plate is used. A plate thickness of each of the first member 10 and the second member 20 may be 0.6 mm to 2.0 mm. For example, the plate thickness of each of the first member 10 and the second member 20 is 1.0 mm. In the present disclosure, an application range of a tensile strength of each of the first member 10 and the second member 20 is 270 MPa to 1470 MPa. In a case where the tensile strength of each of the first member 10 and the second member 20 is within the application range, effects of the present disclosure can be obtained. More preferably, in a case where the tensile strength of each of the first member 10 and the second member 20 is 980 MPa to 1470 MPa, a gap between the first member 10 and the second member 20 is more likely to occur, and thus a contribution of the present disclosure is more likely to be achieved. The tensile strength of each of the first member 10 and the second member 20 in the present embodiment is, for example, around 1470 MPa.

The plate thicknesses of the first member 10 and the second member 20 may be different from each other. Specifically, the plate thickness of the second member 20 may be greater than the plate thickness of the first member 10. In this case, for example, the plate thickness of the first member 10 may be 0.8 mm and the plate thickness of the second member 20 may be 1.2 mm. Hereinafter, a configuration will be described in which the plate thickness of the second member 20 is greater than the plate thickness of the first member 10.

[Overall Shape of Formed Product]

The formed product 1 is formed in a saddle shape having a height. The “saddle shape” as used herein refers to a shape having a top plate portion 11, 21, and a vertical wall portion 12, 22 that is located on both sides of the top plate portion 11, 21 and that extends in directions intersecting the top plate portion 11, 21. The formed product 1 is used to cover an elongated object, such as a cable and a columnar member, along its longitudinal directions, or to reinforce other plate members by being attached thereto.

The formed product 1 is obtained by processing the plate members. The formed product 1 comprises the first member 10 and the second member 20 as the plate members. Hereinafter, the first member 10 and the second member 20 are also collectively referred to as “two plate members”.

The first member 10 includes the top plate portion 11, the vertical wall portion 12, and a flange portion 13. The second member 20 is placed on the first member 10 from below the first member 10. In FIG. 1, for explanation purposes, the top plate portion 11 is shown as an upper portion of the formed product 1. However, the formed product 1 may be used in any orientation. For example, the formed product 1 may be used in an orientation that is upside down compared to the orientation shown in FIG. 1.

The top plate portion 11 is substantially flat plate-shaped and is substantially rectangular-shaped in a plan view. A length of the top plate portion 11 in its width directions (that is, left-right directions in FIG. 1B) is, for example, around 150 mm, and a length of the top plate portion 11 in its longitudinal directions (that is, “b” in FIG. 4A) is, for example, around 350 mm. Two welding portions 11J are formed at a center of the top plate portion 11. In the two welding portions 11J, the top plate portion 11 of the first member 10 and the top plate portion 21 of the second member 20 are joined to each other by spot-welding. Hereinafter, a plane in which the top plate portion 11 is located may be simply referred to as “top plate portion 11”.

Portions along two opposite edges of the top plate portion 11 are bent. Each of the bent portions includes the vertical wall portion 12. The vertical wall portion 12 is a portion that is flat plate-shaped, adjacent to the top plate portion 11, and contiguous to the top plate portion 11, and that extends from the top plate portion 11 in a direction intersecting the plane in which the top plate portion 11 is located. A length of the vertical wall portion 12 (that is, a height from the top plate portion 11 to the flange portion 13) is, for example, around 60 mm.

Additionally, welding portions 12J are formed in the vertical wall portion 12, 22. Two welding portions 12J are formed in the vertical wall portion 12, 22 (that is, a total of four welding portions 12J are formed in the formed product 1). Adding the two welding portions 11J in the top plate portion 11, 21, the first member 10 and the second member 20 of the formed product 1 are joined to each other via a total of six welding portions 11J, 12J.

The flange portion 13 is formed to overhang from an end of the vertical wall portion 12. In other words, the flange portion 13 extends outward from the end of the vertical wall portion 12. The flange portion 13 extends generally parallel to the top plate portion 11. The flange portion 13 is substantially flat plate-shaped and is substantially rectangular-shaped in a plan view. A length of the flange portion 13 in its width directions is, for example, around 20 mm.

As shown in FIG. 1B, a left half and a right half of the formed product 1 of the present embodiment are symmetrical. Therefore, the following explanation may be made focusing on only one of the left half and the right half of the formed product 1. It should be noted that the left half and the right half of the formed product 1 do not necessarily need to be symmetrical.

As shown in FIG. 1B, an end portion of the first member 10 in its width directions is referred to as a first end 13E, and an end portion of the second member 20 in its width directions is referred to as a second end 22E. The second member 20 does not reach the flange portion 13 of the first member 10, and the second end 22E is located between the top plate portion 11 and the flange portion 13 of the first member 10. That is, a length of the vertical wall portion 22 of the second member 20 (that is, a height from the top plate portion 21 to the second end 22E) is shorter than the length of the vertical wall portion 12 of the first member 10.

As shown in FIG. 1B, a region of the first member 10 from the first end 13E to a portion of the first member 10 on which the second end 22E is placed is defined as an “extending portion 14”. The extending portion 14 includes a part of the vertical wall portion 12 of the first member 10 (that is, a portion of the vertical wall portion 12 on a side closer to the flange portion 13 with respect to the second end 22E) and the flange portion 13.

In the two plate members before main forming (S50), which will be described below, a portion corresponding to a whole of the top plate portion 11, 21 of the formed product 1 is also referred to as “top plate corresponding portion”. The top plate corresponding portion includes: a first top plate corresponding portion that is the top plate corresponding portion of the first member 10; and a second top plate corresponding portion that is the top plate corresponding portion of the second member 20. Similarly, a portion corresponding to a part of the vertical wall portion 12 of the formed product 1 (that is, a portion of the vertical wall portion 12 on a side closer to the top plate portion 11 with respect to the second end 22E) and a portion corresponding to a whole of the vertical wall portion 22 are also referred to as “vertical wall corresponding portion”. The vertical wall corresponding portion includes: a first vertical wall corresponding portion that is the vertical wall corresponding portion of the first member 10; and a second vertical wall corresponding portion that is the vertical wall corresponding portion of the second member 20.

As shown in FIG. 1B, and the like, in any planes parallel to the two plate members (for example, the top plate portion 11, 21), a portion on a downstream side in a direction in a plan view from the vertical wall corresponding portion toward the top plate corresponding portion is defined as “inner side”, and a portion on a downsteram side in a direction in a plan view from the vertical wall corresponding portion toward an opposite side to the top plate corresponding portion is defined as “outer side”.

[1-2 . . . Press-Forming Device]

Each of FIGS. 2A and 2B is a cross-sectional view of a press-forming device 100 for forming the formed product 1. The press-forming device 100 comprises a first metal press mold 40 as a punch, a second metal press mold 50 as a die, and a blank holder 60. The first metal press mold 40 and the second metal press mold 50 are displaceable relative to each other in height directions of the formed product 1 by a driving mechanism (not shown). The height directions of the formed product 1 are, for example, directions perpendicular to the top plate portion 11, which correspond to vertical directions in FIG. 2A. The press-forming device 100 is configured such that the second metal press mold 50 is displaced in the height directions without the first metal press mold 40 being displaced. Among the height directions, a direction in which the second metal press mold 50 is moved during the pressing is referred to as “moving direction M”. It should be noted that, the first metal press mold 40 may be displaced in the height directions instead of the second metal press mold 50, or both the second metal press mold 50 and the first metal press mold 40 may be displaced in the height directions.

The blank holder 60 is attached to the second metal press mold 50 to face the first metal press mold 40 and is disposed vertically above the first metal press mold 40. The second metal press mold 50 has a built-in mechanism, such as a gas cylinder. The blank holder 60 is configured to be moved downward by the mechanism, such as a gas cylinder, at the same time as the second metal press mold 50 begins to be moved in the vertical directions, and to be able to clamp the first member 10 and the second member 20 between the blank holder 60 and the first metal press mold 40 before the second metal press mold 50 contacts the two plate members.

The second metal press mold 50, the first metal press mold 40, and the blank holder 60 work together to perform the press-forming. The second metal press mold 50 and the first metal press mold 40 are interlockable with each other and face each other across a space therebetween before press working. In one example, the second metal press mold 50 has a concave shape, and the first metal press mold 40 has a convex shape.

Each of the first metal press mold 40 and the second metal press mold 50 has a shape that conforms to the shape of the formed product 1. Specifically, each of the first metal press mold 40 and the second metal press mold 50 comprises a vertical wall-forming portion 41, 51, a flange-forming portion 42, 52, a depth-extending portion 43, 53, and a shoulder portion 44, 54, respectively. The vertical wall-forming portion 41, 51 is a portion for forming the vertical wall portion 12, 22. The flange-forming portion 42, 52 is a portion for forming the flange portion 13. The depth-extending portion 43, 53 is a wall-like portion that extends substantially in the vertical directions and is a portion that couples the flange-forming portion 42, 52 and the shoulder portion 44, 54 to each other, respectively.

The shoulder portion 44, 54 is a surface parallel to the flange-forming portion 42, 52. The shoulder portion 44, 54 is located on the outer side and on a downstream side in the moving direction M with respect to the flange-forming portion 42, 52, respectively. The shoulder portion 44, 54 is located on the downstream side in the moving direction M with respect to an end of the vertical wall-forming portion 41, 51 on the downstream side in the moving direction M and is located on the outer side with respect to the vertical wall-forming portion 41, 51, respectively.

The shoulder portion 44, 54 includes a surface whose angle to the moving direction M is greater than that of the vertical wall portion 12, 22. In other words, the angle formed by the moving direction M (that is, a vertical straight line) and the surface included in the shoulder portion 44, 54 (for example, a surface extending generally along horizontal directions) is greater than an angle formed by the moving direction M and a surface included in the vertical wall portion 12, 22 (for example, a surface extending generally along the vertical directions).

Accordingly, the second metal press mold 50 has a step shape. The term “step shape” as used herein referred to a shape having surfaces substantially parallel to the top plate portion 11, 21 (for example, the flange-forming portion 52 and the shoulder portion 54).

[1-3. Method of Manufacturing Formed Product]

Next, a method of manufacturing the formed product 1 will be explained. In the present embodiment, operations are performed in accordance with a procedure shown in FIG. 3 to manufacture the formed product 1.

In the method of manufacturing the formed product 1, as shown in FIG. 3, blanking (S10) is performed at first. The term “blanking” as used herein refers to an operation of cutting out blank materials for materials of the formed product 1 by, for example, cutting out portions from a rolled steel plate. At this time, the second member 20 is cut out so that a length of the second member 20 in its width directions is shorter than a length of the first member 10 in its width directions.

Subsequently, in S20, the two plate members, that is, the first member 10 and the second member 20 are joined to each other by welding the top plate portion 11 and the top plate portion 21. In the welding, as shown in FIG. 4, the two plate members are arranged so that the second member 20 is completely covered by the first member 10 in a plan view. Specifically, the second end 22E, which is the end portion of the second member 20, is disposed so as to locate on the inner side with respect to the first end 13E, which is the end portion of the first member 10, and in this state, the two welding portions 11J are formed.

In the configuration of the present embodiment, the first member 10 and the second member 20 are made of the same materials, and a thickness t₁ of the second member 20 is greater than a thickness to of the first member 10, as shown in FIG. 4B. In this case, second moments of area of the two plate members are compared and expressed by bt₀³/12≤bt₁³/12, which indicates that the second moment of area of the first member 10 is equal to or smaller than the second moment of area of the second member 20. It is considered that, in such a case, an effect of curving the first member 10 is more likely to be obtained, and that an amount of springback of the first member 10 becomes equal to or smaller than an amount of springback of the second member 20. It should be noted that “b” is a width of a material (for example, a length in the longitudinal directions in FIG. 2A). In other words, it is considered that, in a case where the first member 10 and the second member 20 are made of the same materials, if the thickness t₁ of the second member 20 is equal to or greater than the thickness to of the first member 10, a gap between the vertical wall portion 12 and the vertical wall portion 22 is reduced.

Subsequently, in S30, the top plate portion 11, 21 of the two plate members, in which the two welding portions 11J are formed, is clamped. That is, in a state where a space is formed between the blank holder 60 and the first metal press mold 40, the two plate members, in which the two welding portions 11J are formed, are placed on the first metal press mold 40, as shown in FIG. 2A. At this time, the first member 10 is disposed on a side closer to the second metal press mold 50 (that is, vertically upper side) with respect to the second member 20. In a line of sight along the moving directions M, the second end 22E is disposed on the inner side with respect to the shoulder portion 54. This is intended to enable the shoulder portion 54 to contact the extending portion 14.

Then, as shown in FIG. 2B, the blank holder 60 is moved in the moving direction M to close the space between the blank holder 60 and the first metal press mold 40. In this way, the top plate portion 11, 21 of the two plate members is clamped between the blank holder 60 and the first metal press mold 40.

Subsequently, in S40, the two plate members are curved. In a state where the top plate portion 11, 21 is clamped using the blank holder 60, the second metal press mold 50 is moved in the moving direction M. As a result, as shown in FIG. 2B, the shoulder portion 54 contacts the extending portion 14. At this time, the vertical wall-forming portion 51, the flange-forming portion 52, and the depth-extending portion 53 do not contact the first member 10.

Then, the second metal press mold 50 is further moved in the moving direction M from the state of FIG. 2B. As a result, the two plate members are pushed by the second metal press mold 50 to be brought into a curved state, as shown in FIG. 5A.

Subsequently, in S50, a main forming is performed. The second metal press mold 50 is further moved in the moving direction M from the state of FIG. 5A. As a result, while curvatures of the two plate members becoming greater, the vertical wall-forming portion 41, 51 and the flange-forming portion 42, 52 eventually clamp the two plate members therebetween to complete the press working, as shown in FIG. 5B.

Subsequently, in S60, welding of the vertical wall portion 12 and the vertical wall portion 22 is performed. That is, after the bending of the vertical wall portion 12, 22, the welding portions 12J are formed in the vertical wall portion 12, 22. After the welding of the vertical wall portion 12 and the vertical wall portion 22 is finished, the formed product 1 is completed. It should be noted that drilling, trimming, and the like may be performed after the welding of the vertical wall portion 12 and the vertical wall portion 22.

[1-4. Discussion on Metal Press Mold Shape]

The following Table 1 shows results of measuring size of the gap between the vertical wall portion 12 and the vertical wall portion 22 while varying a length L of the flange-forming portion 42, 52 and a depth D of the depth-extending portion 43, 53 in the first metal press mold 40 and the second metal press mold 50.

As shown in FIG. 2A, the length L represents a length of the flange-forming portion 42, 52 in the horizontal directions, and the depth D represents a length of the depth-extending portion 43, 53 in the vertical directions. Values of the gap are measured at a position of one of the welding portions 12J.

	TABLE 1
		L [mm]	D [mm]	Size of Gap [mm]

	example 1	30	45	1.61
	example 2	45	45	1.67
	example 3	60	45	1.95
	example 4	30	60	1.59
	example 5	30	90	1.54

In the present result, as shown in Table 1, a tendency was observed in which the size of the gap increases as the length L is increased. It is considered that, as the length L is reduced, an amount of deformation caused by curving of the two plate members becomes larger, and consequently, the size of the gap becomes smaller.

Furthermore, in the present result, a tendency was observed in which the size of the gap becomes smaller as the depth D is increased. However, if the depth D is increased, sizes of the first metal press mold 40 and the second metal press mold 50 become larger, resulting in a higher cost. For this reason, it is considered preferable to set the depth D to be approximately the length of the vertical wall portion 12, 22 in the vertical directions.

1-5. Effects

According to the embodiment explained above in detail, the following effects can be obtained.

(1a) In the method of manufacturing the formed product 1 described above, joining the first member 10 and the second member 20 to each other is performed by welding the top plate corresponding portions to each other in a state where the first member 10 is placed on the second member 20 to include the extending portion 14. In addition, curving the vertical wall corresponding portions and the extending portion 14 of the plate members toward the moving direction M is performed by moving the second metal press mold 50 in the moving direction M in a state where the top plate corresponding portions after the joining are clamped to thereby make the second metal press mold 50 contact the extending portion 14. At this time, the second metal press mold 50 is made to contact the extending portion 14 without the second metal press mold 50 being made to contact any portions of the first member 10 other than the extending portion 14.

Furthermore, forming the top plate portion 11, 21 and the vertical wall portion 12, 22 is performed by further moving the second metal press mold 50 in the moving direction M in a state where the vertical wall corresponding portions and the extending portion 14 are curved by the second metal press mold 50 to thereby press the vertical wall corresponding portions of the plate members by the second metal press mold 50.

In such a method of manufacturing, the top plate portion 11, 21 and the vertical wall portion 12, 22 are formed after the second metal press mold 50 is made to contact the extending portion 14 to curve the plate members. In other words, the top plate portion 11, 21 and the vertical wall portion 12, 22 are formed after the plate members are slightly curved. Therefore, it is possible to reduce the springback of the vertical wall portion 12, 22. The reduction in the springback of the vertical wall portion 12, 22 allows the gap between the vertical wall portion 12 and the vertical wall portion 22 to become smaller, and consequently, operations, such as welding, after press working to be performed effectively.

(1b) In one mode of the present disclosure, the shoulder portion 54 is located on the downstream side in the moving direction M with respect to the end of the vertical wall-forming portion 51 on the downstream side in the moving direction M. The shoulder portion 54 includes the surface on the outer side with respect to the vertical wall-forming portion 51 whose angle to the moving direction M is greater than an angle of the vertical wall portion 12, 22 to the moving direction M. Furthermore, in the curving, the second end 22E is disposed on the inner side with respect to the shoulder portion 54, and the vertical wall corresponding portions and the extending portion 14 of the plate members are curved toward the moving direction M by the shoulder portion 54 contacting the extending portion 14.

In such a method of manufacturing, it is possible to achieve a configuration in which the plate members are curved by the shoulder portion 54 contacting the extending portion 14.

(1c) In one mode of the present disclosure, the second metal press mold 50 has the step shape. The second metal press mold 50 comprises the flange-forming portion 52 and the shoulder portion 54 as surfaces forming the step shape. In the curving, the vertical wall corresponding portions and the extending portion 14 of the plate members are curved toward the moving direction M by the shoulder portion 54 contacting the extending portion 14. Furthermore, in the forming of the top plate portion 11, 21 and the vertical wall portion 12, 22, the flange portion 13 extending toward the outer side from the vertical wall portion 12, 22 is formed by the flange-forming portion 52 contacting the extending portion 14.

In such a method of manufacturing, also in a case of manufacturing the formed product 1 having the flange portion 13, it is possible to form the top plate portion 11, 21 and the vertical wall portion 12, 22 after the plate members are curved.

(1d) In one mode of the present disclosure, in the forming of the top plate portion 11, 21 and the vertical wall portion 12, 22, the forming of the flange portion 13 is completed on the inner side with respect to the shoulder portion 54. It should be noted that the forming of the flange portion 13 may be started while the shoulder portion 54, 72, 82 coming into contact with the flange portion 13 and then completed on the inner side with respect to the shoulder portion 54, 72, 82.

In such a method of manufacturing, it is possible to make the shoulder portion 54 contact the plate members from further outer side, and thus it is possible to form the top plate portion 11, 21 and the vertical wall portion 12, 22 after the plate members are sufficiently curved.

(1e) In one mode of the present disclosure, the plate thickness of the second member 20 may be equal to or greater than the plate thickness of the first member 10.

In such a method of manufacturing, the second moment of area of the first member 10 is likely to be equal to or smaller than the second moment of area of the second member 20, and thus the effect of curving the first member 10 is more likely to be obtained. As a result, it is possible to reduce the springback of the first member 10 and to make the gap between the first member 10 and the second member 20 smaller.

(1f) In one mode of the present disclosure, the first member 10 and the second member 20 are welded to each other in the vertical wall portion 12, 22 after the top plate portion 11, 21 and the vertical wall portion 12, 22 are formed.

In such a method of manufacturing, since the springback of the vertical wall portion 12, 22 is reduced, the gap between the first member 10 and the second member 20 becomes smaller. Therefore, welding operation can be performed effectively.

(1g) In one mode of the present disclosure, the formed product 1 may be an automobile part. In such a method of manufacturing, it is possible to effectively manufacture the formed product 1 to be applied to the automobile part.

2. Other Embodiment

Although the embodiment of the present disclosure has been explained, the present disclosure is not limited to the aforementioned embodiment and may be practiced in various other forms.

(2a) In the aforementioned embodiment, the press-forming device 100 is used. However, for example, a press-forming device 110 of a first modified example shown in FIGS. 6A and 6B may be used. In the press-forming device 100 of the aforementioned embodiment, a configuration has been exemplified in which the second metal press mold 50 is moved in the vertical directions. However, the press-forming device 110 of the first modified example comprises a second metal press mold 70, as a cam, instead of the second metal press mold 50. The second metal press mold 70 comprises a vertical wall-forming portion 71 and a flange-forming portion 72 (the shoulder portion in the present disclosure). A first metal press mold 40 comprises only a vertical wall-forming portion 41 and a flange-forming portion 42.

As shown in FIG. 6A, a moving direction M of the second metal press mold 70 is directed toward the two plate members from diagonally above the two plate members. That is, the moving direction M of the second metal press mold 70 is a direction of a combination of a vertically downward component and a component directed toward the inner side from the outer side.

In this configuration, as the second metal press mold 70 is moved in the moving direction M, firstly the flange forming portion 72 contacts the extending portion 14, which is indicated by a double-dot chain line in FIG. 6A. Then, as the second metal press mold 70 is further moved, the two plate members are curved. Subsequently, as shown in FIG. 6B, the vertical wall portion 12, 22 and the flange portion 13 are formed.

(2b) In addition, for example, instead of the press-forming device 100 of the aforementioned embodiment, a press-forming device 120 of a second modified example shown in FIGS. 7A and 7B may be used. The press-forming device 120 of the second modified example is a device for obtaining a formed product that does not comprise the flange portion 13, that is, a formed product that comprises only the top plate portion 11, 21 and the vertical wall portion 12, 22.

The press-forming device 120 of the second modified example comprises a second metal press mold 80 instead of the second metal press mold 50. The second metal press mold 80 comprises a vertical wall-forming portion 81 and a shoulder portion 82. Although the shoulder portion 54 of the aforementioned embodiment extends in the horizontal directions, the shoulder portion 82 of the second modified example comprises an inclined surface that slopes downward in the moving direction M as the inclined surface extends toward the outer side. Also the shoulder portion 82 comprises a surface whose angle to the moving direction M is greater than that of the vertical wall portion 12, 22.

Even in such a configuration, the shoulder portion 82 contacts the two plate members before the vertical wall-forming portion 81 contacts the two plate members, and thus it is possible to perform the press-forming after the plate members are curved. Therefore, it is possible to reduce the springback.

(2c) Alternatively, the second metal press mold 50 may comprise a shoulder portion formed as a curved surface. In this case, it is preferable to set an angle formed by a plane extending along a tangent line of the curved surface and the moving direction M greater than an angle formed by a plane extending along the vertical wall portion 12, 22 and the moving direction M.

Even in such a configuration, it is possible to perform the press-forming after the plate members are curved.

(2d) A configuration has been exemplified in which the formed product 1 is formed in the saddle shape that have the vertical wall portions 12, 22 on the both sides of the top plate portion 11, 21, but a configuration of the formed product 1 is not limited to the aforementioned configuration. For example, the formed product 1 may be formed in a single-sided bent shape that have the vertical wall portion 12, 22 on only one side of the top plate portion 11, 21.

(2e) Two or more functions performed by one element in the aforementioned embodiment may be achieved by two or more elements. One function performed by one element may be achieved by two or more elements. Two or more functions performed by two or more elements may be achieved by one element. One function performed by two or more elements may be achieved by one element. Furthermore, a part of the configuration in the aforementioned embodiment may be omitted. Still further, at least a part of the configuration in the aforementioned embodiment may be added to or replaced with another part of the configuration in the aforementioned embodiment.

(2f) Without being limited to the method of manufacturing the formed product described above, it is possible to achieve the present disclosure in various modes, such as a formed product having a top plate portion and a vertical wall portion.