MANUFACTURING METHOD OF PRESS-FORMED PRODUCT

Abstract

In order to manufacture a press-formed product including a plate-shaped portion and a wall portion, a blank having a plate shape is clamped by and between a first clamping structure located on a first side in a thickness direction of the blank with respect to the blank and a second clamping structure located on a second side opposite the first side in the thickness direction with respect to the blank. The wall portion is formed in the blank by press-forming performed by moving a first die in a pressing direction that is parallel to the thickness direction and that allows the first die to relatively come closer to the blank. The plate-shaped portion with a recessed part is formed in the blank by press-forming performed by further moving the first die in the pressing direction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Patent Application No. 2023-198227 filed on Nov. 22, 2023 with the Japan Patent Office, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

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

A technique is known for forming a stretch flange in a blank having a plate shape by press-forming. The stretch flange is obtained by a processing of bending the blank, for example, and a ridge line corresponding to a part where the blank is bent has an arc shape recessed toward a non-bent part of the blank.

Japanese Unexamined Patent Application Publication No. 2017-042826 discloses a technique, in forming the stretch flange in the blank by press-forming, for inhibiting occurrence of wrinkling in the blank by clamping and fixing the blank by and between a punch and a pad.

SUMMARY

A case will be discussed of forming a press-formed product including, in addition to the stretch flange, a recessed part recessed in a plate thickness direction in a plate-shaped portion, which is a portion opposite the stretch flange with respect to the ridge line.

In the conventional technique, such as that disclosed in Japanese Unexamined Patent Application Publication No. 2017-042826, in a case where the stretch flange and the recessed part are formed concurrently by press-forming, in order to form the recessed part using the punch and the pad that clamp the blank therebetween, the punch or the pad needs to be provided with a protruding part that protrudes in the plate thickness direction. Thus, when the blank is clamped by and between the punch and the pad, the protruding part causes an interspace sized larger than or equal to the thickness of the blank between the blank and the punch or between the blank and the pad.

When the stretch flange is formed by press-forming with the interspace generated between the blank and the punch or between the blank and the pad, the blank is prone to wrinkling, especially when the blank is made of a material with less stretchiness, such as a high tensile strength steel sheet.

Accordingly, when the press-formed product with the stretch flange and the recessed part is to be obtained, formation of the recessed part needs to be performed in the step after formation of the stretch flange in order to inhibit occurrence of wrinkling during the formation of the stretch flange. Moreover, another die for forming the recessed part needs to be prepared separately from a die used for the stretch flange.

In one aspect of the present disclosure, it is desirable to reduce the number of steps for press-forming.

One aspect of the present disclosure is a manufacturing method of a press-formed product including: a plate-shaped portion with a recessed part recessed in a first thickness direction of the plate-shaped portion; and a wall portion extending from an edge of the plate-shaped portion in a direction intersecting with the plate-shaped portion. The manufacturing method of the press-formed product comprises: clamping a blank; forming the wall portion in the blank, and forming the plate-shaped portion with the recessed part in the blank.

The clamping the blank includes clamping the blank by and between a first clamping structure and a second clamping structure. The first clamping structure is on a first side in a second thickness direction, which is a thickness direction of the blank having a plate shape. The second clamping structure is on a second side opposite the first side in the second thickness direction with respect to the blank.

The forming the wall portion in the blank includes forming the wall portion in the blank by performing press-forming on the blank clamped by and between the first clamping structure and the second clamping structure, and the press-forming is performed by moving at least one of a first die or a clamping/clamped body in a pressing direction. The first die is located on the first side with respect to the blank. The clamping/clamped body is a collection including the first clamping structure, the second clamping structure, the blank, and a second die. The second die is located on the second side with respect to the blank. The pressing direction is a direction that is parallel to the second thickness direction and that allows the first die to relatively come closer to the blank.

The forming the plate-shaped portion with the recessed part in the blank includes forming the plate-shaped portion with the recessed part in the blank by performing press-forming on the blank that is in the process of having the wall portion formed therein, and the press-forming is performed by further moving the at least one of the first die or the clamping/clamped body in the pressing direction so as to allow the first die and the second die to come closer to each other.

In such a configuration, it is possible to form the wall portion and the recessed part in the blank by moving the object in the same pressing direction in a state where the first die and the second die are arranged in advance on the first side and the second side, respectively, with respect to the blank. This enables reduction in the number of steps for press-forming.

In one aspect of the present disclosure, the forming the wall portion in the blank may include forming the wall portion by moving the first die in the pressing direction. The forming the plate-shaped portion with the recessed part in the blank may include forming the plate-shaped portion by further moving the first die in the pressing direction so that the recessed part is formed in the blank by the first die and the second die coming closer to each other.

In such a configuration, it is possible to form the wall portion and the recessed part in the blank through a single movement of the first die in the pressing direction. This enables reduction in the number of steps for press-forming.

In one aspect of the present disclosure, the plate-shaped portion may include a first recessed part and a second recessed part. The first recessed part is formed as the recessed part. The second recessed part is recessed more shallowly in the first thickness direction than the first recessed part. The clamping the blank may include clamping the blank by and between the first clamping structure and the second clamping structure to thereby form the second recessed part in the blank.

In such a configuration, it is possible to form the second recessed part recessed more shallowly than the first recessed part when clamping the blank by and between the first clamping structure and the second clamping structure. This enables reduction in the number of steps for press-forming.

In one aspect of the present disclosure, the clamping the blank may include clamping the blank by and between the first clamping structure and the second clamping structure at at least two points apart from each other in a direction perpendicular to the second thickness direction. The at least two points may include a first point and a second point. The forming the plate-shaped portion may include forming the recessed part in the blank by moving at least one of the first die or the second die such that a part of the at least one of the first die or the second die passes through in between the first point and the second point.

In such a configuration, it is possible to form the recessed part between the two points on the blank clamped by and between the first clamping structure and the second clamping structure.

In one aspect of the present disclosure, the blank may be formed of a high tensile strength steel sheet.

In such a configuration, it is possible to inhibit occurrence of cracking and wrinkling in the press-formed product when manufacturing the press-formed product from the blank formed of a high tensile strength steel sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the present disclosure will be described below with reference to the accompanying drawings, in which:

FIG. 1 is a schematic perspective view of a press-formed product;

FIG. 2 is a schematic perspective view of an upper pad, a blank, a lower pad, and a lower die;

FIG. 3 is a sectional view, along a pressing direction, of the blank and structures therearound in a clamping step;

FIG. 4 is a sectional view, along the pressing direction, of the blank and the structures therearound in a wall portion forming step;

FIG. 5 is a sectional view, along the pressing direction, of the blank and the structures therearound in a top plate portion forming step;

FIG. 6 is an additional sectional view of a section, along the pressing direction, of the blank and the structures therearound in the clamping step;

FIG. 7 is an additional sectional view of a section, along the pressing direction, of the blank and the structures therearound in the wall portion forming step;

FIG. 8 is an additional sectional view of a section, along the pressing direction, of the blank and the structures therearound in the top plate portion forming step;

FIG. 9 is a sectional view, along the pressing direction, of the blank and the structures therearound in a wall portion forming step in another embodiment;

FIG. 10 is a sectional view, along the pressing direction, of the blank and the structures therearound in a wall portion forming step in still another embodiment;

FIG. 11 is a schematic perspective view of a press-formed product in which a recessed part is located along an edge of a plate-shaped portion in yet another embodiment;

FIG. 12 is a schematic perspective view of a press-formed product in which a recessed part extends from a first end to a second end of a plate-shaped portion in a further embodiment;

FIG. 13 is a schematic perspective view of a press-formed product in which a recessed part has a gently raised shape in a still further embodiment;

FIG. 14 is a flowchart showing a manufacturing method of the press-formed products;

FIG. 15A is a perspective view of another press-formed product;

FIG. 15B is a top view of the press-formed product in FIG. 15A; and

FIG. 15C is a side view of the press-formed product in FIG. 15A.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Embodiments of the present disclosure are not limited to the embodiments to be described below, and may take various forms as long as they fall within the technical scope of the present disclosure.

1. First Embodiment

A press-formed product 1 shown in FIG. 1 is an exemplary press-formed product for describing a manufacturing method of a press-formed product according to a first embodiment. The manufacturing method in the present embodiment can be used not only for manufacturing the press-formed product 1 shown in FIG. 1 but also for manufacturing press-formed products with various shapes. The manufacturing method in the present embodiment may be used for manufacturing a press-formed product with any shape including, for example, a plate-shaped portion with a recessed part recessed in a thickness direction of the plate-shaped portion and a wall portion extending from an edge of the plate-shaped portion in a direction intersecting with the plate-shaped portion.

[1-1. Structure of Press-Formed Product]

The press-formed product 1 shown in FIG. 1 is formed by press-forming a metal material. The press-formed product 1 is formed of a high tensile strength steel sheet. For example, the press-formed product 1 may be formed of a high tensile strength steel sheet with a tensile strength of 980 MPa or greater, or may be formed of a high tensile strength steel sheet with a tensile strength of 1180 MPa or greater.

The press-formed product 1 comprises a top plate portion 2, a wall portion 3, and a bottom plate portion 4.

Most of the top plate portion 2, excluding some parts, extends on the same plane. The top plate portion 2 has a plate shape. The top plate portion 2 may be curved in a thickness direction thereof, or does not have to be curved in the thickness direction. Hereinafter, the thickness direction of the top plate portion 2 is referred to as an up-down direction. The thickness direction may be read as a right-left direction or a front-rear direction, without being limited to the up-down direction. “Up” and “down” in the up-down direction may be read interchangeably.

The top plate portion 2 comprises a first upwardly recessed part 21a, a first downwardly recessed part 21b, a second upwardly recessed part 22a, and a second downwardly recessed part 22b.

The first upwardly recessed part 21a is recessed upward in the top plate portion 2. The first downwardly recessed part 21b is recessed downward in the top plate portion 2. The depth of the first upwardly recessed part 21a and the depth of the first downwardly recessed part 21b are both larger than the thickness of the top plate portion 2. That is, an upper face of the top plate portion 2 in an area corresponding to the first upwardly recessed part 21a is above an upper face of the top plate portion 2 in an area around the first upwardly recessed part 21a. A lower face of the top plate portion 2 in an area corresponding to the first downwardly recessed part 21b is below a lower face of the top plate portion 2 in an area around the first downwardly recessed part 21b.

The second upwardly recessed part 22a is recessed upward in the top plate portion 2. The second downwardly recessed part 22b is recessed downward in the top plate portion 2. The depth of the second upwardly recessed part 22a and the depth of the second downwardly recessed part 22b are both smaller than the thickness of the top plate portion 2. That is, the depth of the second upwardly recessed part 22a and the depth of the second downwardly recessed part 22b are both smaller than the depth of the first upwardly recessed part 21a and the depth of the first downwardly recessed part 21b.

The positions where the first upwardly recessed part 21a, the first downwardly recessed part 21b, the second upwardly recessed part 22a, and the second downwardly recessed part 22b are provided are not limited in particular as long as they are on the top plate portion 2.

The wall portion 3 extends from an edge of the top plate portion 2 in a direction intersecting with the top plate portion 2. The wall portion 3 has a plate shape. In the present embodiment, the wall portion 3 extends in a downward direction from the edge of the top plate portion 2.

A part where the top plate portion 2 and the wall portion 3 meet forms a ridge line 3a. The ridge line 3a has an arc shape recessed in a direction parallel to the upper face of the top plate portion 2. As shown in FIG. 1, the wall portion 3 is curved along the ridge line 3a. The wall portion 3 corresponds to a stretch flange formed along the edge of the top plate portion 2.

The bottom plate portion 4 extends from an edge of the wall portion 3 opposite where the ridge line 3a is in a direction intersecting with the wall portion 3. The bottom plate portion 4 has a plate shape. The bottom plate portion 4 extends in a direction opposite that in which the top plate portion 2 extends, with respect to the wall portion 3. In the present embodiment, the bottom plate portion 4 is substantially parallel to the top plate portion 2, although not being limited thereto.

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

The press-formed product 1 is formed by performing press-forming on a blank 10 with a press-forming device 5 (see FIGS. 2 to 8). The blank 10 is a plate-shaped material. In the present embodiment, the blank 10 is a high tensile strength steel sheet made of metal, as an example.

As shown in FIGS. 2 to 8, the press-forming device 5 comprises an upper die 61, an upper pad 62, a gas cushion 63, a lower die 71, a lower pad 72, and a die cushion 73.

The upper die 61 is a die for press-forming. The upper die 61 comprises a top face 61a, an upper contact part 61b, an upper wall forming part 61c, an upper bottom-plate forming part 61d, and an upper protruding part 61e.

The top face 61a is on the lower side of part of the upper die 61. The top face 61a extends in a direction perpendicular to the up-down direction (hereinafter referred to as a horizontal direction).

The upper contact part 61b protrudes downward from a part of the top face 61a.

The upper wall forming part 61c is a face extending from a position lower than the upper contact part 61b downwardly and so as to be away from the upper contact part 61b in the horizontal direction. The upper wall forming part 61c is curved so as to be convex toward the side where the upper contact part 61b is located in the horizontal direction. An angle formed between an imaginary plane extended from the upper wall forming part 61c and the top face 61a is substantially the same as an angle formed between the top plate portion 2 and the wall portion 3 in the press-formed product 1.

The upper bottom-plate forming part 61d is a face extending in the horizontal direction from a lower edge of the upper wall forming part 61c so as to be away from the upper wall forming part 61c. The upper bottom-plate forming part 61d is substantially parallel to the horizontal direction.

As shown in FIGS. 6 to 8, the upper protruding part 61e protrudes downward from a part of the top face 61a. A lower end part of the upper protruding part 61e has a shape protruding downward for forming the first downwardly recessed part 21b of the press-formed product 1.

The upper pad 62 is a pad for press-forming. In the present embodiment, a section of the upper pad 62 along the up-down direction has a substantially rectangular shape. As shown in FIG. 2, the upper pad 62 comprises an upper first recess forming part 62a, an upper second recess forming part 62b, and an upper through hole 62c.

As shown in FIGS. 2 and 3, the upper first recess forming part 62a is formed in a lower face of the upper pad 62. The upper first recess forming part 62a is recessed upward. The upper first recess forming part 62a has a shape for forming the first upwardly recessed part 21a of the press-formed product 1.

As shown in FIG. 2, the upper second recess forming part 62b is formed in the lower face of the upper pad 62. The upper second recess forming part 62b is recessed upward or protrudes downward to form, respectively, the second upwardly recessed part 22a or the second downwardly recessed part 22b of the press-formed product 1.

As shown in FIGS. 2 and 6, the upper through hole 62c penetrates the upper pad 62 in the up-down direction.

The gas cushion 63 shown in FIGS. 3 to 8 utilizes a reaction force of compressed gas. The gas cushion 63 expands and contracts in the up-down direction according to changes in pressure.

An upper face of the gas cushion 63 is in contact with the top face 61a. A lower face of the gas cushion 63 is in contact with an upper face of the upper pad 62. The lower face of the gas cushion 63 is below the upper contact part 61b.

The lower die 71 is a die for press-forming. As shown in FIGS. 2 and 3 for example, the lower die 71 comprises a bottom face 71a, a lower contact part 71b, a lower wall forming part 71c, a lower bottom-plate forming part 71d, and a lower protruding part 71e.

The bottom face 71a is on the upper side of part of the lower die 71. The bottom face 71a extends in the horizontal direction.

The lower contact part 71b protrudes upward from part of the bottom face 71a.

The lower wall forming part 71c is a face extending from a position upper than the lower contact part 71b downwardly and so as to be away from the lower contact part 71b in the horizontal direction. The lower wall forming part 71c is curved so as to be convex toward the side where the lower contact part 71b is located in the horizontal direction. In the press-forming device 5, the upper wall forming part 61c and the lower wall forming part 71c are substantially parallel to each other.

The lower bottom-plate forming part 71d extends in the horizontal direction from a lower edge of the lower wall forming part 71c so as to be away from the lower wall forming part 71c. The lower bottom-plate forming part 71d has a plate shape.

The lower protruding part 71e protrudes upward from part of the bottom face 71a. An upper end part of the lower protruding part 71e has a shape protruding upward for forming the first upwardly recessed part 21a of the press-formed product 1.

The lower pad 72 is a pad for press-forming. In the present embodiment, a section of the lower pad 72 along the up-down direction has a substantially rectangular shape. As shown in FIG. 2, the lower pad 72 comprises a lower first recess forming part 72a, a lower second recess forming part 72b, and a lower through hole 72c.

As shown in FIGS. 2 and 6, the lower first recess forming part 72a is formed in an upper face of the lower pad 72. The lower first recess forming part 72a is recessed downward. The lower first recess forming part 72a has a shape for forming the first downwardly recessed part 21b of the press-formed product 1.

As shown in FIG. 2, the lower second recess forming part 72b is formed in the upper face of the lower pad 72. The lower second recess forming part 72b protrudes upward or is recessed downward to form, respectively, the second upwardly recessed part 22a or the second downwardly recessed part 22b of the press-formed product 1.

As shown in FIGS. 2 and 3, the lower through hole 72c penetrates the lower pad 72 in the up-down direction.

As shown in FIGS. 3 to 8, the die cushion 73 is a cushion for press-forming. The die cushion 73 expands and contracts in the up-down direction according to changes in pressure. A reaction force of the die cushion 73 is greater than that of the gas cushion 63.

An upper face of the die cushion 73 is in contact with a lower face of the lower pad 72. A lower face of the die cushion 73 is in contact with the bottom face 71a. The upper face of the die cushion 73 is above the lower contact part 71b.

As shown in FIGS. 2 and 3, the lower pad 72 is arranged above the lower die 71. The blank 10 is arranged over the lower pad 72. The upper pad 62 is arranged over the blank 10. The upper die 61 is moved downward from above the upper pad 62 toward such an arrangement to thereby perform press-forming.

Such press-forming is performed not only by moving the upper die 61. Such press-forming may be performed by moving at least one of the upper die 61 or a clamping/clamped body in a pressing direction that is parallel to the up-down direction and that allows the upper die 61 to relatively come closer to the blank 10. The clamping/clamped body refers to a collection including the upper pad 62, the lower pad 72, the lower die 71, and the blank 10.

As shown in FIG. 14, the manufacturing method of the press-formed product 1 comprises a clamping step S10, a wall portion forming step S20, and a top plate portion forming step S30, which are performed in this order.

[1-3. Manufacturing Method of Press-Formed Product with Upwardly Recessed Part]

The manufacturing method of the press-formed product 1 as viewed in a section including the first upwardly recessed part 21a and the wall portion 3 will be described with reference to FIGS. 3 to 5.

[1-3-1. Clamping Step]

The clamping step S10 is a step of clamping the blank 10 by and between the upper pad 62 located over the blank 10 and the lower pad 72 located under the blank 10, as is shown in FIG. 3.

The upper pad 62 is in contact with an upper face of the blank 10. The lower pad 72 is in contact with a lower face of the blank 10. The blank 10 is clamped by and between the upper pad 62 and the lower pad 72 from the upper side and the lower side, respectively. The upper pad 62, the lower pad 72, and the lower die 71 are arranged such that the positions of the upper first recess forming part 62a of the upper pad 62, the lower through hole 72c in the lower pad 72, and the lower protruding part 71e of the lower die 71 in the horizontal direction are substantially the same as each other.

In this state, the blank 10 receives pressure from the upper pad 62 and the lower pad 72, thus being deformed along the upper second recess forming part 62b and the lower second recess forming part 72b, which are shown in FIG. 2. This results in forming the second upwardly recessed part 22a and the second downwardly recessed part 22b in the blank 10. However, the blank 10 is slidable in the horizontal direction even after the second upwardly recessed part 22a and the second downwardly recessed part 22b are formed in the blank 10.

Hereinafter, an imaginary plane positioned on substantially the same plane as part of the blank 10 in contact with the upper pad 62 and the lower pad 72 is referred to as a reference plane A (see FIGS. 4 and 5).

[1-3-2. Wall Portion Forming Step]

The wall portion forming step S20 is a step of performing press-forming on the blank 10 clamped by and between the upper pad 62 and the lower pad 72 by moving the upper die 61 downward, thus forming the wall portion 3 in the blank 10, as is shown in FIG. 4.

The upper bottom-plate forming part 61d of the upper die 61 performs the press-forming on the blank 10 clamped in the clamping step S10 by being moved toward part of the upper face of the blank 10 not in contact with the upper pad 62.

Part of the blank 10 in contact with the upper bottom-plate forming part 61d receives pressure from the upper bottom-plate forming part 61d, thus being deformed so as to be below the reference plane A. At this time, the blank 10 is bent downward at an edge of the part clamped by and between the upper pad 62 and the lower pad 72. This results in forming the ridge line 3a in the blank 10. Subsequently, the blank 10 is deformed so as to come in close contact with the upper wall forming part 61c. This results in forming the wall portion 3 in the blank 10.

In the wall portion forming step S20, the upper die 61 is moved downward until the upper contact part 61b comes in contact with the upper face of the upper pad 62. At this time, an upper edge of the upper wall forming part 61c is not moved to be below the reference plane A. The blank 10 and the upper first recess forming part 62a are apart from each other. The lower protruding part 71e is below the reference plane A.

The reaction force of the gas cushion 63 is smaller than that of the die cushion 73. Thus, in the wall portion forming step S20, the gas cushion 63 is compressed downward by the top face 61a and the upper pad 62 as a result of the movement of the upper die 61. Although the die cushion 73 receives a downward pressure from the lower pad 72, the die cushion 73 is substantially not deformed.

[1-3-3. Top Plate Portion Forming Step]

The top plate portion forming step S30 is a step of performing press-forming on the blank 10 that is in the process of having the wall portion 3 formed therein by further moving the upper die 61 downward, thus forming the top plate portion 2 with the first upwardly recessed part 21a in the blank 10, as is shown in FIG. 5.

In the top plate portion forming step S30, the upper die 61 is further moved downward continuously from the wall portion forming step S20. At this time, the upper die 61 is moved downward while in contact with the upper pad 62 at the upper contact part 61b and in contact with the gas cushion 63 at the top face 61a. Thus, the upper die 61, the upper pad 62, and the gas cushion 63 are integrally moved downward. The description of the top plate portion forming step S30 below will focus on the movement of the upper pad 62. The upper pad 62 being moved downward means the upper die 61 and the gas cushion 63 being moved downward a distance the same as that the upper pad 62 is moved.

The upper end part of the lower protruding part 71e of the lower die 71 is within the lower through hole 72c in the lower pad 72. The positions of the lower protruding part 71e and the upper first recess forming part 62a of the upper pad 62 in the horizontal direction are substantially the same as each other.

By being pressed downward by the upper pad 62, the part of the blank 10 in contact with the upper pad 62 and the lower pad 72 is moved downward following the upper pad 62 together with the lower pad 72.

Part of the blank 10 in the same position as the upper first recess forming part 62a and the lower through hole 72c in the horizontal direction is moved downward following the upper pad 62, and comes in contact with the upper end part of the lower protruding part 71e. Further downward movement of the upper pad 62 causes the lower pad 72 to move downward, following the upper pad 62, relative to the lower protruding part 71e. Such downward movement of the lower pad 72 relative to the lower protruding part 71e causes the upper end part of the lower protruding part 71e to pass through the lower through hole 72c to come in contact with the blank 10. A part of the blank 10 in contact with the lower protruding part 71e receives an upward pressure from the lower protruding part 71e, thus being deformed so as to be recessed upward of the reference plane A. Further downward movement of the upper pad 62 causes an upper face of the part of the blank 10 in contact with the lower protruding part 71e to come in contact with the upper first recess forming part 62a of the upper pad 62 and subsequently to be further deformed so as to come in close contact with the upper first recess forming part 62a. This results in forming the first upwardly recessed part 21a in the blank 10. In other words, the top plate portion 2 with the first upwardly recessed part 21a is formed in the blank 10.

In the top plate portion forming step S30, the upper pad 62 is moved downward until the blank 10 comes in close contact with the upper first recess forming part 62a. At this time, the upper pad 62 may be moved downward, in the top plate portion forming step S30, until the lower pad 72 comes in contact with an upper face of the lower contact part 71b. The upper pad 62 reaches its bottom dead point by its downward movement in the top plate portion forming step S30.

When the upper pad 62 reaches the bottom dead point, the wall portion 3 formed in the blank 10 is in close contact with the upper wall forming part 61c and the lower wall forming part 71c. A part of the blank 10 extending from the edge of the wall portion 3 opposite the ridge line 3a comes in close contact with the upper bottom-plate forming part 61d and the lower bottom-plate forming part 71d. This results in forming the bottom plate portion 4 in the blank 10.

In the top plate portion forming step S30, the distance between the top face 61a in contact with the gas cushion 63 and the upper pad 62 is constant; thus, the gas cushion 63 is substantially not deformed. The die cushion 73 is compressed downward by the lower pad 72 and the bottom face 71a as a result of the movement of the lower pad 72.

In this way, a part including the first upwardly recessed part 21a and the wall portion 3 in the press-formed product 1 is formed. A sectional view of the blank 10 in FIG. 5 corresponds to a view of a section of the press-formed product 1 taken along line V-V in FIG. 1.

[1-4. Manufacturing Method of Press-Formed Product with Downwardly Recessed Part]

So far, the description has been given of the manufacturing method of the press-formed product 1 with reference to FIGS. 3 to 5, focusing on the section of the press-formed product 1 taken along line V-V in FIG. 1. Hereafter, a description will be given of the manufacturing method of the press-formed product 1 with reference to FIGS. 6 to 8, focusing on a section of the press-formed product 1 taken along line VIII-VIII in FIG. 1. In other words, a description will be given of the manufacturing method of the press-formed product 1 as viewed in a section including the first downwardly recessed part 21b and the wall portion 3 in the press-formed product 1.

[1-4-1. Clamping Step]

In the clamping step S10, as shown in FIG. 6, the upper die 61 and the upper pad 62 are arranged over the blank 10, and the lower pad 72 and the lower die 71 are arranged under the blank 10. To be noted in FIG. 6 is arrangement of the upper protruding part 61e of the upper die 61, the upper through hole 62c in the upper pad 62, and the lower first recess forming part 72a of the lower pad 72, for forming the first downwardly recessed part 21b. The upper die 61, the upper pad 62, and the lower pad 72 are arranged such that the positions of the upper protruding part 61e, the upper through hole 62c, and the lower first recess forming part 72a in the horizontal direction are substantially the same as each other.

[1-4-2. Wall Portion Forming Step]

In the wall portion forming step S20, as shown in FIG. 7, in the process until the upper contact part 61b comes in contact with the upper face of the upper pad 62, the upper die 61 is moved downward so that the upper protruding part 61e comes in contact with the upper face of the blank 10.

When the upper protruding part 61e comes in contact with the upper face of the blank 10, the upper contact part 61b is apart from the upper pad 62. Part of the upper wall forming part 61c near the upper edge thereof is not yet moved downward of the reference plane A. A lower end part of the upper protruding part 61e is within the upper through hole 62c in the upper pad 62. The blank 10 and the lower first recess forming part 72a are apart from each other. A part of the lower pad 72 is in contact with the upper face of the lower contact part 71b.

Part of the blank 10 in contact with the lower edge of the upper wall forming part 61c (i.e., a part where the upper wall forming part 61c and the upper bottom-plate forming part 61d meet) is deformed so as to be lower than the reference plane A by receiving pressure from the upper wall forming part 61c. In other words, the blank 10 is bent downward at an edge of the part clamped by and between the upper pad 62 and the lower pad 72. At this time, the blank 10 is in the process of having the wall portion 3 formed therein.

[1-4-3. Top Plate Portion Forming Step]

In the top plate portion forming step S30, as shown in FIG. 8, the press-forming progresses, on the blank 10 in the process of having the wall 3 formed therein, by further moving the upper die 61 downward. As a result, the top plate portion 2 with the first downwardly recessed part 21b is formed in the blank 10.

In this step, the upper die 61 is further moved downward continuously from the wall portion forming step S20.

A part of the upper protruding part 61e is within the upper through hole 62c in the upper pad 62.

In this step, the lower pad 72 is in contact with the upper face of the lower contact part 71b. Thus, downward movement of the lower pad 72 is restricted. A part of the blank 10 in contact with the upper protruding part 61e receives a downward pressure from the upper protruding part 61e, thus being deformed so as to be recessed downward of the reference plane A. Further downward movement of the upper die 61 causes a lower face of the part of the blank 10 in contact with the upper protruding part 61e to come into contact with the lower first recess forming part 72a of the lower pad 72 and to be further deformed so as to come in close contact with the lower first recess forming part 72a. This results in forming the first downwardly recessed part 21b in the blank 10. In other words, the top plate portion 2 with the first downwardly recessed part 21b is formed in the blank 10.

In this step, the upper die 61 is moved downward until the blank 10 comes in close contact with the lower first recess forming part 72a. At this time, the upper die 61 may be moved downward until the upper contact part 61b comes in contact with the upper pad 62. The upper die 61 may be moved downward until the upper edge of the upper wall forming part 61c comes in contact with the blank 10. The upper die 61 reaches its bottom dead point by its downward movement in this step.

When the upper die 61 reaches the bottom dead point, a part of the blank 10 located between the upper wall forming part 61c and the lower wall forming part 71c is in close contact with the upper wall forming part 61c and the lower wall forming part 71c. This results in forming the wall portion 3 in the blank 10. The part of the blank 10 extending from the lower edge of the wall portion 3 comes in close contact with the upper bottom-plate forming part 61d and the lower bottom-plate forming part 71d. This results in forming the bottom plate portion 4 in the blank 10.

In this step, the gas cushion 63 is compressed downward by the top face 61a and the upper pad 62 as a result of the movement of the upper die 61. Since the distance between the bottom face 71a in contact with the die cushion 73 and the lower pad 72 is constant, the die cushion 73 is substantially not deformed.

In this way, a part including the first downwardly recessed part 21b and the wall portion 3 in the press-formed product 1 is formed. A sectional view of the blank 10 in FIG. 8 corresponds to a view of the section of the press-formed product 1 taken along line VIII-VIII in FIG. 1.

[1-5. Actions and Effects]

The above-detailed embodiment provides the actions and effects described below.

• • (1a) In the wall portion forming step S20 shown in FIGS. 4 and 7, the press-forming device 5 performs press-forming by moving the upper die 61 downward, thus forming the wall portion 3 in the blank 10. Subsequently, in the top plate portion forming step S30 shown in FIGS. 5 and 8, the press-forming device 5 performs press-forming by moving the upper die 61 further downward, thus respectively forming the first upwardly recessed part 21a and the first downwardly recessed part 21b in the blank 10. In the top plate portion forming step S30, the upper die 61 is moved downward continuously from the wall portion forming step S20.

In such a configuration, the upper die 61 is moved downward only once throughout the wall portion forming step S20 and the top plate portion forming step S30. Thus, it is possible to form the wall portion 3, the first upwardly recessed part 21a, and the first downwardly recessed part 21b in the blank 10 through such a single press-forming. This enables reduction in the number of steps for press-forming.

• • (1b) The depths of the second upwardly recessed part 22a and the second downwardly recessed part 22b are smaller than those of the first upwardly recessed part 21a and the first downwardly recessed part 21b. The second upwardly recessed part 22a and the second downwardly recessed part 22b are formed in the blank 10 by receiving pressures from the upper pad 62 and the lower pad 72 in the clamping step S10.

In such a configuration, it is possible to form the second upwardly recessed part 22a and the second downwardly recessed part 22b, which are relatively shallow, when clamping the blank 10 by and between the upper pad 62 and the lower pad 72. This enables reduction in the number of steps for press-forming.

In addition, the depths of the second upwardly recessed part 22a and the second downwardly recessed part 22b are smaller than the thickness of the top plate portion 2. Thus, when the second upwardly recessed part 22a and the second downwardly recessed part 22b are clamped by and between the upper pad 62 and the lower pad 72, it is possible to inhibit generation of an interspace sized larger than or equal to the thickness of the blank 10 between the blank 10 and the upper pad 62 and between the blank 10 and the lower pad 72, respectively.

• • (1c) The first upwardly recessed part 21a and the first downwardly recessed part 21b are not clamped by and between the upper pad 62 and the lower pad 72.

In such a configuration, the first upwardly recessed part 21a and the first downwardly recessed part 21b, which are relatively deep, are less susceptible to pressure from the upper pad 62 and the lower pad 72. This makes it possible to inhibit occurrence of wrinkling and cracking in the first upwardly recessed part 21a and the first downwardly recessed part 21b.

• • (1d) In the wall portion forming step S20, a part of the blank 10 is clamped by and between the upper pad 62 and the lower pad 72.

In such a configuration, when the blank 10 is bent downward in the wall portion forming step S20, occurrence of wrinkling in the blank 10 can be inhibited.

• • (1e) Even after the second upwardly recessed part 22a and the second downwardly recessed part 22b are formed in the blank 10 in the clamping step S10, the blank 10 is slidable in the horizontal direction. In the wall portion forming step S20, neither the first upwardly recessed part 21a nor the first downwardly recessed part 21b has been formed in the blank 10.

In such a configuration, when the blank 10 is bent downward in the wall portion forming step S20, sliding of the blank 10 causes inflow of the material in the part where the blank 10 is bent. This makes it possible to inhibit occurrence of cracking in the blank 10 in the wall portion forming step S20.

[1-6. Correspondence Relationships Between Terms]

In the above-described embodiment, the top plate portion 2 corresponds to an example of the plate-shaped portion, the upper side corresponds to an example of the first side in the thickness direction, and the lower side corresponds to an example of the second side in the thickness direction.

The upper pad 62 corresponds to an example of the first clamping structure, the lower pad 72 corresponds to an example of the second clamping structure, the upper die 61 corresponds to an example of the first die, and the lower die 71 corresponds to an example of the second die.

The first upwardly recessed part 21a and the first downwardly recessed part 21b each correspond to an example of the recessed part and an example of the first recessed part, and the second upwardly recessed part 22a and the second downwardly recessed part 22b each correspond to an example of the second recessed part.

In a part of the upper pad 62 adjacent to the upper through hole 62c, two points located across the upper through hole 62c from each other in a radial direction of the upper through hole 62c correspond to an example of the first point and an example of the second point, respectively.

In a part of the lower pad 72 adjacent to the lower through hole 72c, two points located across the lower through hole 72c from each other in a radial direction of the lower through hole 72c correspond to an example of the first point and an example of the second point, respectively.

The clamping step S10 corresponds to an example of clamping the blank, the wall portion forming step S20 corresponds to an example of forming the wall portion in the blank, and the top plate portion forming step S30 corresponds to an example of forming the plate-shaped portion with the recessed part in the blank.

[2. Other Embodiments]

Although the embodiment of the present disclosure has been described so far, the present disclosure may take various forms without being limited to the embodiment described above.

• • (2a) In the above-described embodiment, the first upwardly recessed part 21a is formed by bringing the blank 10 into close contact with the upper first recess forming part 62a of the upper pad 62 by press-forming. However, the structure to form the first upwardly recessed part 21a is not limited to the upper first recess forming part 62a. For example, a press-forming device 105 shown in FIG. 9 may be employed that includes an upper die 161 with an upper recessed part 161f, instead of the upper die 61, and an upper pad 162 with an upper through hole 162c, instead of the upper pad 62.

The upper recessed part 161f protrudes downward from a part of the top face 61a. A lower end part of the upper recessed part 161f has a shape recessed upward for forming the first upwardly recessed part 21a of the press-formed product 1.

The upper through hole 162c penetrates the upper pad 162 in the up-down direction.

In the present case, in the top plate portion forming step S30, a lower part of the upper recessed part 161f is within the upper through hole 162c. The lower end part of the upper recessed part 161f is a substitute for the upper first recess forming part 62a. When the upper die 161 is moved downward, a part of the blank 10 in contact with the lower protruding part 71e receives an upward pressure from the lower protruding part 71e, thus being deformed so as to be recessed upward of the reference plane A, then coming in contact with the lower end part of the upper recessed part 161f, and then being further deformed so as to come in close contact with the lower end part of the upper recessed part 161f. This results in forming the first upwardly recessed part 21a in the blank 10.

• • (2b) In the above-described embodiment, the first downwardly recessed part 21b is formed by bringing the blank 10 into close contact with the lower first recess forming part 72a of the lower pad 72 by press-forming. However, the structure to form the first downwardly recessed part 21b is not limited to the lower first recess forming part 72a. For example, a press-forming device 205 shown in FIG. 10 may be employed that includes a lower die 271 with a lower top face 271a and a lower recessed part 271f, instead of the lower die 71 and the lower pad 72.

The lower top face 271a is on the upper side of part of the lower die 271. The lower top face 271a extends in the horizontal direction. Throughout the clamping step S10, the wall portion forming step S20, and the top plate portion forming step S30, the lower top face 271a is in contact with the lower face of the blank 10 to clamp the blank 10.

The lower recessed part 271f is formed in the lower top face 271a. The lower recessed part 271f is recessed downward. The lower recessed part 271f has a shape for forming the first downwardly recessed part 21b of the press-formed product 1.

In the present case, in the top plate portion forming step S30, a lower face of the blank 10 including the part thereof in contact with the upper protruding part 61e is in contact with the lower recessed part 271f, which is a substitute for the lower first recess forming part 72a, and such a part of the blank 10 is deformed so as to come in close contact with the lower recessed part 271f. This results in forming the first downwardly recessed part 21b in the blank 10.

In the above-described embodiment, the lower die 271 corresponds to an example of the second clamping structure.

• • (2c) In the above-described embodiment, the first upwardly recessed part 21a is formed in a position other than where the edge of the top plate portion 2 is present. However, the position where the first upwardly recessed part 21a is formed is not limited to this. For example, as in a press-formed product 101 shown in FIG. 11, a first upwardly recessed part 121a may be formed in a part of a top plate portion 102 continuous to the wall portion 3. Alternatively, as in a press-formed product 201 shown in FIG. 12, a first upwardly recessed part 221a may be formed so as to extend from an edge of a top plate portion 202 continuous to the wall portion 3 to an edge of the top plate portion 202 opposite the wall portion 3.
  • (2d) In the above-described embodiment, the first upwardly recessed part 21a and the first downwardly recessed part 21b each have an angular shape. However, the shapes of the first upwardly recessed part 21a and the first downwardly recessed part 21b do not have to be angular. For example, as in a press-formed product 301 shown in FIG. 13, a first upwardly recessed part 321a may be formed on a top plate portion 302 to have a gently raised shape. The shape of the first upwardly recessed part 321a may be a preliminary shape prior to being shaped to be angular.
  • (2e) The manufacturing method in the above-described embodiment is used for manufacturing the exemplary press-formed product 1. However, the manufacturing method of press-formed products is not limited to being used for manufacturing the press-formed product 1. For example, as shown in FIGS. 15A, 15B, and 15C, the manufacturing method may be used for manufacturing a press-formed product 401 having a configuration equivalent to that of the press-formed product 1.

The press-formed product 401 comprises a top plate portion 402, a wall portion 403, and a bottom plate portion 404, as portions corresponding to the top plate portion 2, the wall portion 3, and the bottom plate portion 4 of the press-formed product 1. A part where the top plate portion 402 and the wall portion 403 meet forms a ridge line 403a as a part corresponding to the ridge line 3a.

The top plate portion 402 is curved toward the thickness direction. In a case of forming the press-formed product 401 in which the top plate portion 402 is curved toward the thickness direction using the press-forming device 5, faces of the upper pad 62 and the lower pad 72 each in contact with the blank 10 are curved along the curve of the top plate portion 402.

The top plate portion 402 comprises a first upwardly recessed part 421a, a first downwardly recessed part 421b, a second upwardly recessed part 422a, and a second downwardly recessed part 422b, as parts corresponding to the first upwardly recessed part 21a, the first downwardly recessed part 21b, the second upwardly recessed part 22a, and the second downwardly recessed part 22b.

The positions where the first upwardly recessed part 421a, the first downwardly recessed part 421b, the second upwardly recessed part 422a, and the second downwardly recessed part 422b are arranged are not limited in particular as long as they are on the top plate portion 402.

For example, the press-formed product 401 is used as a member forming a body of a vehicle. The press-formed product 401 may be used as a member forming a portion of a vehicle other than the body. The press-formed product 401 may be used as a member not mounted in the vehicle.

• • (2f) In the above-described embodiment, the wall portion 3 has a shape corresponding to a stretch flange. However, the shape of the wall portion 3 is not limited to that of the stretch flange. For example, the shape of the wall portion 3 may be that corresponding to a bent flange or a shrink flange.
  • (2g) Functions of a single element in the above-described embodiments may be performed by a plurality of elements, and a single function of a single element may be performed by a plurality of elements. Functions of a plurality of elements may be performed by a single element, and a single function performed by a plurality of elements may be performed by a single element. Part of the configuration in the above-described embodiments may be omitted. At least part of the configuration in the above-described embodiments may be added to or replace a configuration in other embodiments.

[Technical Ideas Disclosed Herein]

[Item 1]

A manufacturing method of a press-formed product including: a plate-shaped portion with a recessed part recessed in a first thickness direction of the plate-shaped portion; and a wall portion extending from an edge of the plate-shaped portion in a direction intersecting with the plate-shaped portion, the manufacturing method comprising:

• • clamping a blank having a plate shape by and between a first clamping structure and a second clamping structure, the first clamping structure being on a first side in a second thickness direction, which is a thickness direction of the blank, the second clamping structure being on a second side opposite the first side in the second thickness direction with respect to the blank;
  • forming the wall portion in the blank by performing press-forming on the blank clamped by and between the first clamping structure and the second clamping structure, the press-forming being performed by moving at least one of a first die located on the first side with respect to the blank or a clamping/clamped body, which is a collection including the first clamping structure, the second clamping structure, the blank, and a second die, in a pressing direction that is parallel to the second thickness direction and that allows the first die to relatively come closer to the blank, the second die being located on the second side with respect to the blank; and
  • forming the plate-shaped portion with the recessed part in the blank by performing press-forming on the blank that is in the process of having the wall portion formed therein, the press-forming being performed by further moving the at least one of the first die or the clamping/clamped body in the pressing direction so as to allow the first die and the second die to come closer to each other.

[Item 2]

The manufacturing method of a press-formed product according to Item 1,

• • wherein the forming the wall portion in the blank includes forming the wall portion by moving the first die in the pressing direction, and
  • wherein the forming the plate-shaped portion with the recessed part in the blank includes forming the plate-shaped portion by further moving the first die in the pressing direction so that the recessed part is formed in the blank by the first die and the second die coming closer to each other.

[Item 3]

The manufacturing method of a press-formed product according to Item 1 or 2,

• • wherein the plate-shaped portion includes a first recessed part as the recessed part and a second recessed part recessed more shallowly in the first thickness direction than the first recessed part, and
  • wherein the clamping the blank includes clamping the blank by and between the first clamping structure and the second clamping structure to thereby form the second recessed part in the blank.

[Item 4]

The manufacturing method of a press-formed product according to any one of Items 1 to 3,

• • wherein the clamping the blank includes clamping the blank by and between the first clamping structure and the second clamping structure at at least two points apart from each other in a direction perpendicular to the second thickness direction,
  • wherein the at least two points include a first point and a second point, and
  • wherein the forming the plate-shaped portion includes forming the recessed part in the blank by moving at least one of the first die or the second die such that a part of the at least one of the first die or the second die passes through in between the first point and the second point.

[Item 5]

The manufacturing method of a press-formed product according to any one of Items 1 to 4,

• • wherein the blank is formed of a high tensile strength steel sheet.

Claims

1. A manufacturing method of a press-formed product including: a plate-shaped portion with a recessed part recessed in a first thickness direction of the plate-shaped portion; and a wall portion extending from an edge of the plate-shaped portion in a direction intersecting with the plate-shaped portion, the manufacturing method comprising: clamping a blank having a plate shape by and between a first clamping structure and a second clamping structure, the first clamping structure being on a first side in a second thickness direction, which is a thickness direction of the blank, the second clamping structure being on a second side opposite the first side in the second thickness direction with respect to the blank;forming the wall portion in the blank by performing press-forming on the blank clamped by and between the first clamping structure and the second clamping structure, the press-forming being performed by moving at least one of a first die located on the first side with respect to the blank or a clamping/clamped body, which is a collection including the first clamping structure, the second clamping structure, the blank, and a second die, in a pressing direction that is parallel to the second thickness direction and that allows the first die to relatively come closer to the blank, the second die being located on the second side with respect to the blank; andforming the plate-shaped portion with the recessed part in the blank by performing press-forming on the blank that is in the process of having the wall portion formed therein, the press-forming being performed by further moving the at least one of the first die or the clamping/clamped body in the pressing direction so as to allow the first die and the second die to come closer to each other.

2. The manufacturing method of a press-formed product according to claim 1, wherein the forming the wall portion in the blank includes forming the wall portion by moving the first die in the pressing direction, andwherein the forming the plate-shaped portion with the recessed part in the blank includes forming the plate-shaped portion by further moving the first die in the pressing direction so that the recessed part is formed in the blank by the first die and the second die coming closer to each other.

3. The manufacturing method of a press-formed product according to claim 1, wherein the plate-shaped portion includes a first recessed part as the recessed part and a second recessed part recessed more shallowly in the first thickness direction than the first recessed part, andwherein the clamping the blank includes clamping the blank by and between the first clamping structure and the second clamping structure to thereby form the second recessed part in the blank.

4. The manufacturing method of a press-formed product according to claim 1, wherein the clamping the blank includes clamping the blank by and between the first clamping structure and the second clamping structure at at least two points apart from each other in a direction perpendicular to the second thickness direction,wherein the at least two points include a first point and a second point, andwherein the forming the plate-shaped portion includes forming the recessed part in the blank by moving at least one of the first die or the second die such that a part of the at least one of the first die or the second die passes through in between the first point and the second point.

5. The manufacturing method of a press-formed product according to claim 1, wherein the blank is formed of a high tensile strength steel sheet.