Method for producing press-formed product and automobile lower arm

1. A method for producing a press-formed product from a blank metal plate,

wherein the press-formed product includes a main body part that bends along a lengthwise direction in plan view and has a first end part and a second end part respectively on both ends of the main body part, and a protruded part that protrudes outward of bending from a bent part of the main body part,

the main body part and the protruded part each comprise top plate parts and vertical wall parts each extending from opposite sides of the top plate parts,

a groove part along the lengthwise direction of the main body part is provided on a surface of the top plate part of the main body part,

among the vertical wall parts, the vertical wall part extending from the first end part of the main body part to the protruded part has a corner part connecting the main body part and the protruded part, and

in a ridge part formed by the top plate part and the vertical wall part extending from the first end part of the main body part to the protruded part, an angle that is formed by a part which is on the main body side from the corner part and a part which is on the protruded part side from the corner part is an acute angle,

the method for producing the press-formed product comprising: a first step; and a second step,

wherein in the first step, by applying press-working to the blank metal plate, a surface shape on the second end part side from the bent part of the main body part is formed, in a surface shape of the top plate part, and further the vertical wall part extending from the first end part side of the main body part to the protruded part is formed, and

in the second step, a surface shape on the first end part side from the bent part of the main body part is formed, in the surface shape of the top plate part, by applying press-working to the blank metal plate after the first step.

2. The method for producing a press-formed product according to claim 1 ,

wherein the groove part of the press-formed product is provided in a domain from the first end part to the second end part so as to pass through a root of the protruded part, in the surface of the top plate part of the main body part,

in the first step, a part on the second end part side of the groove part is formed, and

in the second step, a part on the first end part side of the groove part is formed.

3. The method for producing a press-formed product according to claim 2 ,

wherein in the first step, when a circle having a radius of 35% of a length of the main body part is drawn centered at a point that is located nearest to the second end part side in the corner part, a part or a whole of a portion on the second end part side of the groove part is located in the circle.

4. The method for producing a press-formed product according to claim 1 ,

wherein the groove part of the press-formed product is provided in a domain on the first end part side from a root of the protruded part, in the surface of the top plate part of the main body part,

the groove part is not formed in the first step, and

the groove part is formed in the second step.

5. The method for producing a press-formed product according to claim 1 ,

wherein the press-formed product is an automobile lower arm,

the first end part and the protruded part of the main body part are attached to a vehicle body of an automobile, and

the second end part of the main body part is attached to a vehicle wheel of the automobile.

6. An automobile lower arm formed from a blank metal plate by press-working,

the lower arm, comprising: a main body part that bends along a lengthwise direction in plan view and has a vehicle body attaching end part and a vehicle wheel attaching end part respectively on both ends of the main body part; and a vehicle body attaching protruded part that protrudes outward of bending from a bent part of the main body part,

wherein the main body part and the protruded part each comprise top plate parts, and vertical wall parts each extending from opposite sides of the top plate parts,

a groove part along the lengthwise direction of the main body part is provided on a surface of the top plate part of the main body part,

among the vertical wall parts, the vertical wall part extending from the vehicle body attaching end part of the main body part to the protruded part has a corner part connecting the main body part and the protruded part, and

in a ridge part formed by the top plate part and the vertical wall part extending from the vehicle body attaching end part of the main body part to the protruded part, an angle that is formed by a part which is on the main body part side from the corner part and a part which is on the protruded part side from the corner part is an acute angle,

a tensile strength TS [MPa]of the automobile lower arm is 440 MPa or more, and

a maximum height H max [mm]of the corner part of the vertical wall part satisfies Formula (1) as follows:

H max >−0.0103×TS+26.051  (1).

7. The method for producing a press-formed product according to claim 2 ,

wherein the press-formed product is an automobile lower arm,

the first end part and the protruded part of the main body part are attached to a vehicle body of an automobile, and

the second end part of the main body part is attached to a vehicle wheel of the automobile.

8. The method for producing a press-formed product according to claim 3 ,

wherein the press-formed product is an automobile lower arm,

the first end part and the protruded part of the main body part are attached to a vehicle body of an automobile, and

the second end part of the main body part is attached to a vehicle wheel of the automobile.

9. The method for producing a press-formed product according to claim 4 ,

wherein the press-formed product is an automobile lower arm,

the first end part and the protruded part of the main body part are attached to a vehicle body of an automobile, and

the second end part of the main body part is attached to a vehicle wheel of the automobile.