Method for Manufacturing Press-Formed Product

This application claims the benefit of Japanese Patent Application No. 2024-073642 filed on Apr. 30, 2024 with the Japan Patent Office, the entire disclosure of which is incorporated herein by reference.

The present disclosure relates to a method for manufacturing a press-formed product by press forming.

Japanese Unexamined Patent Application Publication No. 2021-194687 discloses a well-known technique for forming a member having a plate-shaped top plate extending in its longitudinal direction and a plate-shaped vertical wall protruding from an end of the top plate in its width direction by press forming.

In the manufacturing method disclosed in Japanese Unexamined Patent Application Publication No. 2021-194687, a part corresponding to a top plate of a workpiece is held between a first die and a second die when the above-described member is formed. Then, by moving a third die adjacent to the first die relative to the first die and the second die, the vertical wall is formed.

According to the technique disclosed in Japanese Unexamined Patent Application Publication No. 2021-194687, the member is formed while the top plate is held between the first die and the second die. Thus, it is possible to inhibit wrinkles from being formed on the top plate during press forming. However, with the method of Japanese Unexamined Patent Application Publication No. 2021-19468, it is not possible to apply sufficient pressure to the vertical wall during press forming, and wrinkles may be formed on the vertical wall.

In one aspect of the present disclosure, it is desirable to inhibit formation of wrinkles during press forming.

On aspect of the present disclosure provides a method for manufacturing a press-formed product, and the method comprises: forming a first formed product by press forming a plate-shaped blank material; forming a second formed product by press forming the first formed product; and forming the press-formed product by press forming the second formed product. The press-formed product is a member extending in its longitudinal direction, and comprises a top plate and two vertical walls. The top plate is an elongated plate-shaped portion extending in the longitudinal direction. The two vertical wall are wall-like portions protruding on a first side from opposite ends of the top plate in a width direction of the top plate. The first formed product is a member extending in the longitudinal direction, and includes a preliminary top plate, an inclined section, and a flat section. The preliminary top plate is an elongated plate-shaped portion extending in the longitudinal direction. The inclined section is a plate-shaped portion extending in a curved manner on the first side from a first end of the preliminary top plate in a width direction of the preliminary top plate. The flat section is a plate-shaped portion extending from an end of the inclined section opposite the preliminary top plate. The second formed product is a member extending in the longitudinal direction, and includes the preliminary top plate, the inclined section, and a preliminary vertical wall. The preliminary vertical wall is a wall-like portion protruding on the first side from the end of the inclined section opposite the preliminary top plate. The preliminary vertical wall is formed by deforming the flat section while the preliminary top plate and the inclined section in the first formed product are held between dies.

According to the configuration above, the preliminary top plate and the inclined section of the first formed product are held between the dies when the preliminary vertical wall is formed. Thus, it is possible to inhibit wrinkles from being formed during press forming.

In one aspect of the present disclosure, the first formed product may be formed by holding a blank material between a first die disposed on the first side and a second die disposed on a second side opposite the first side. The preliminary vertical wall may be formed by pressing the flat section from the second side with a third die disposed on the second side while the preliminary top plate and the inclined section in the first formed product are held between the first die and the second die.

According to the configuration above, the preliminary top plate, the inclined section, and the preliminary vertical wall can be appropriately formed.

In one aspect of the present disclosure, the press-formed product may be formed by pressing and deforming the inclined section with a sixth die disposed on the first side while the preliminary top plate in the second formed product is held between a fourth die disposed on the second side opposite the first side and a fifth die disposed on the first side.

According to the configuration above, it is possible to appropriately form the top plate and one of the two vertical walls corresponding to part of the inclined section and the preliminary vertical wall in the second formed product, in the press-formed product.

In one aspect of the present disclosure, the inclined section and the preliminary vertical wall may contact the fourth die and the sixth die when the press-formed product is formed by press forming the second formed product.

According to the configuration above, it is possible to appropriately form one of the two vertical walls in the press-formed product corresponding to part of the inclined section and the preliminary vertical wall in the second formed product.

In one aspect of the present disclosure, the second formed product may include a flange that is a plate-shaped portion bulging from an end of the preliminary vertical wall opposite the inclined section. The flange in the second formed product may correspond to part of the flat section of the first formed product. When the press-formed product is formed by press forming the second formed product, the flange in the second formed product may contact the fourth die and the sixth die.

According to the configuration above, it is possible to appropriately form the flange.

In one aspect of the present disclosure, press forming for forming the first formed product, the second formed product, and the press-formed product may be performed by displacing the dies along a first direction. The press-formed product may include a first top plate end that is located in a width direction of the top plate and corresponds to part of the inclined section in the second formed product. A distance in the first direction between an end of the preliminary top plate on the inclined section side and an end of the preliminary vertical wall opposite the inclined section, in a first cross section of the second formed product orthogonal to the longitudinal direction, is defined as a first distance. A distance in the first direction between the first top plate end and an end of one of the two vertical walls protruding from the first top plate end, in a cross section of the press-formed product orthogonal to the longitudinal direction corresponding to the first cross section, is defined as a second distance. The first distance and the second distance may be approximately the same.

According to the configuration above, it is possible to appropriately form the top plate and one of the two vertical walls corresponding to part of the inclined section and the preliminary vertical wall in the second formed product in the press-formed product.

In one aspect of the present disclosure, the top plate may include a curved section that is a curved area that bulges out toward the first side in a cross section along the longitudinal direction. The second formed product may include the inclined section in part corresponding to the curved section of the press-formed product.

According to the configuration above, it is possible to inhibit wrinkles from being formed in the curved section during press forming.

In one aspect of the present disclosure, the press-formed product may be made from high-tensile steel having a tensile strength of 980 MPa or more.

According to the configuration above, it is possible to inhibit wrinkles from being formed while the press-formed product is formed.

In one aspect of the present disclosure, the press-formed product may be installed on a vehicle.

According to the configuration above, it is possible to inhibit wrinkles from being formed while the press-formed product to be installed on a vehicle is formed.

In one aspect of the present disclosure, the press-formed product may form part of a vehicle body.

According to the configuration above, it is possible to inhibit wrinkles from being formed while the press-formed product that forms part of a vehicle body is formed.

A press-formed productof the first embodiment is formed by press forming a metal material (see). In the first embodiment, high-tensile steel having a tensile strength of 980 MPa or more is used as the metal material. However, the metal material is not limited to this. The metal material may be, for example, high-tensile steel having a tensile strength of 1470 MPa or more, may be high-tensile steel having a tensile strength less than 980 MPa, or may be stainless steel or iron.

In addition, the press-formed productis used as a member that forms part of a vehicle body, as an example. However, the press-formed productis not limited to this. The press-formed productmay be used as a member that forms a part other than a vehicle body, or may be used as a member not installed on a vehicle.

The press-formed productis a plate-shaped member, and comprises a top plate, a vertical wall, a flange, an opposing vertical wall, and an opposing flange(see).

The press-formed productis a groove-shaped member, and extends from a first endto a second endalong its longitudinal direction. The press-formed productalso has a curved shape so that the first endand the second endprotrude toward a second side D, that is, with a center area of the press-formed productbulging out toward a first side Din a cross section along the longitudinal direction (see). The first side Dis a side on which the flangeand the opposing flangeare located relative to the top plate, and the second side Dis opposite the first side D. Of course, the shape of the press-formed productis not limited to this. The press-formed productmay have a straight-lined shape in the cross section along the longitudinal direction.

The top plateis an elongated plate-shaped portion extending from the first endto the second endalong the longitudinal direction. The press-formed producthas a longer length in its width direction (hereinafter, simply referred to as “width direction”) from a center area of the top platein the longitudinal direction toward the second end. The top plateincludes a curved section.

The curved sectionis a plate-shaped portion located in a curved area that bulges out toward the first side Din the cross section along the longitudinal direction of the top plate. The curved sectionis located substantially in the center of the top platein the longitudinal direction.

The vertical wallis a plate-shaped portion protruding on the first side Dfrom one end of the top platein the width direction (hereinafter, referred to as “first top plate end”), and extends from the first endto the second endof the top plate. The vertical wallincludes an upper vertical wall, a first stepped section, a second stepped section, and a lower vertical wall.

The upper vertical wallis a wall-like portion protruding on the first side Dfrom the first top plate end.

The first stepped sectionand the second stepped sectionare step-shaped portions that are located at an end of the upper vertical wallopposite the top plateand protrude opposite the opposing vertical wall. The first stepped sectionand the second stepped sectionare aligned in the longitudinal direction. The first stepped sectionis located on the first endside, and the second stepped sectionis located on the second endside. In addition, the first stepped sectionhas an approximately triangular shape when viewed from the second side D(see). An end portion forming one side of the first stepped sectionextends along an end portion of the upper vertical wall. The vertical walldoes not have to have the first stepped sectionand the second stepped section. In other words, the vertical wallmay be, for example, a wall-like portion that protrudes straight out on the first side Dfrom the first top plate endwithout bending.

The lower vertical wallis a wall-like portion that protrudes on the first side Dfrom ends of the first stepped sectionand the second stepped sectionopposite the opposing vertical wall.

The flangeis a plate-shaped portion protruding opposite the opposing vertical wallfrom an end of the lower vertical wallopposite the first stepped sectionand the second stepped section.

The opposing vertical wallis a plate-shaped portion that protrudes on the first side Dfrom an end of the top plateopposite the first top plate end. The opposing vertical wallfaces the vertical wallin the width direction. The opposing vertical wallmay include a step-shaped portion like the first stepped sectionand the second stepped sectionof the vertical wall.

In a cross section orthogonal to the longitudinal direction of the press-formed product, a length of the opposing vertical wallprotruding on the first side Dis preferably less than or equal to a length of the vertical wallprotruding on the first side D, and more preferably less than the length of the vertical wallprotruding on the first side D.

The opposing flangeis a plate-shaped portion protruding opposite the vertical wallfrom an end of the opposing vertical wallopposite the top plate.

The method for manufacturing the press-formed productcomprises a first process, a second process, and a third process. In the first process, a first formed productis formed by press forming a blank material B (see). In the second process, a second formed productis formed by press forming the first formed product(see). In the third process, the press-formed productis formed by press forming the second formed product(see).

In the first process, the first formed productis formed by press forming the plate-shaped blank material B, which is made from the above-described metal material and extends along the longitudinal direction, using a press forming machine (see).

The press forming machine in the first process comprises a first lower die, an upper pad, and a first upper die, which are dies for press forming.

The first lower dieis located below the blank material B. The first lower dieextends along the longitudinal direction and protrudes on the upper side in a cross section orthogonal to the longitudinal direction (hereinafter, simply referred to as “cross section”). The first lower dieincludes a preliminary top plate shaper, an inclination shaper, a preliminary vertical wall shaper, a flange shaper, an opposing vertical wall shaper, and an opposing flange shaper.

The preliminary top plate shaperis a shaping surface that extends along the longitudinal direction and forms a top surface of a portion of the first lower dieprotruding on the upper side.

The inclination shaperis a shaping surface extending downward in a curved manner from one end of the preliminary top plate shaperin the width direction.

The preliminary vertical wall shaperis a shaping surface extending downward from an end of the inclination shaperopposite the preliminary top plate shaper. The preliminary vertical wall shaperhas a smaller angle relative to an up-down direction in press forming than the inclination shaper.

The flange shaperis a shaping surface extending opposite the opposing vertical wall shaperfrom an end of the preliminary vertical wall shaperopposite the inclination shaper.

The opposing vertical wall shaperis a shaping surface extending downward from an end of the preliminary top plate shaperopposite the inclination shaper.

The opposing flange shaperis a shaping surface extending opposite the flange shaperfrom an end of the opposing vertical wall shaperopposite the preliminary top plate shaper. The opposing flange shaperis located on an upper side compared to the flange shaper.