The steering angles of front wheels 3f and rear wheels 3r of a vehicle 1 can be respectively controlled by a front wheel steering angle control actuator 35 and a rear wheel steering angle control actuator 44. If a steering wheel 20 is operated in a turning direction of the vehicle 1 while the vehicle 1 is traveling in a straight line, then a controller 60 changes the steering angle of the front wheels 3f to approach to a steering angle specified on the basis of an operation amount after the steering wheel 20 is operated, and also controls the front wheel steering angle control actuator 35 and the rear wheel steering angle control actuator 44 to change the steering angles of the rear wheels 3r to the opposite direction of the turning direction of the vehicle 1 immediately after the steering wheel 20 is operated.

The steering angles of front wheels 3f and rear wheels 3r of a vehicle 1 can be respectively controlled by a front wheel steering angle control actuator 35 and a rear wheel steering angle control actuator 44. If a steering wheel 20 is operated in a turning direction of the vehicle 1 while the vehicle 1 is traveling in a straight line, then a controller 60 changes the steering angle of the front wheels 3f to approach to a steering angle specified on the basis of an operation amount after the steering wheel 20 is operated, and also controls the front wheel steering angle control actuator 35 and the rear wheel steering angle control actuator 44 to change the steering angles of the rear wheels 3r to the opposite direction of the turning direction of the vehicle 1 immediately after the steering wheel 20 is operated.

This torsion beam manufacturing method is for manufacturing a torsion beam including a central portion of which a cross-section orthogonal to a longitudinal direction is a closed cross-section having a substantial V-shape or a substantial U-shape at any position in the longitudinal direction, and a shape changing portion which has a connection region leading to the central portion and including a closed cross-section having a shape different from the shape of the closed cross-section of the central portion.

This torsion beam manufacturing method has a compression step of thickening at least the connection region through application of a compression force in the longitudinal direction to at least the connection region of a torsion beam material to obtain the torsion beam, the torsion beam material being formed with the central portion and the shape changing portion.

This torsion beam manufacturing method is a method of manufacturing a torsion beam that includes a uniformly shaped closed cross-sectional portion of which a cross section orthogonal to a longitudinal direction is a closed cross section having a substantial V-shape or a substantial U-shape at any position in the longitudinal direction, and a shape changing portion which has a connection region leading to the uniformly shaped closed cross-sectional portion and including a closed cross section having a shape different from the shape of the closed cross section of the uniformly shaped closed cross-sectional portion. The torsion beam manufacturing method includes pulling process of applying a tensile force in the longitudinal direction to at least the connection region of a torsion beam material including the uniformly shaped closed cross-sectional portion and the shape changing portion, to obtain the torsion beam.

This torsion beam manufacturing method is a method of manufacturing a torsion beam that includes a uniformly shaped closed cross-sectional portion of which a cross section orthogonal to a longitudinal direction is a closed cross section having a substantial V-shape or a substantial U-shape at any position in the longitudinal direction, and a shape changing portion which has a connection region leading to the uniformly shaped closed cross-sectional portion and including a closed cross section having a shape different from the shape of the closed cross section of the uniformly shaped closed cross-sectional portion. The torsion beam manufacturing method includes pulling process of applying a tensile force in the longitudinal direction to at least the connection region of a torsion beam material including the uniformly shaped closed cross-sectional portion and the shape changing portion, to obtain the torsion beam.

The production method disclosed is a method for producing a front axle beam. The production method includes a die forging step and a bending step. The die forging step is a step of forging a steel material with dies to produce a forged product including a rough web part, which is to be formed into a web part, and four plate-shaped rough flange parts protruding frontward and rearward from an upper side and a lower side of the rough web part, respectively. The bending step is a step of pressing at least one specified rough flange part, which is at least one of the four rough flange parts, with a first die to form a bent portion in the specified rough flange part such that the bent portion is bent inward in an up-down direction of the forged product.

There is provided an end plate that includes a through hole that causes an outer wall portion and an inner wall portion to communicate with each other, into which an intruding portion provided in a wheel-side member can intrude, a first press-formed portion formed by depressing in a peripheral edge of the through hole in the inner wall portion. The end plate includes a second press-formed portion arranged in a part of a peripheral edge on the side of a peripheral end of the inner wall portion, which is a remnant of a portion where the first press-formed portion is arranged in the inner wall portion, and formed therein with a protruding portion by protruding a part of the peripheral edge, and a screw hole formed by penetrating through the protruding portion in the second press-formed portion between the outer wall portion and the inner wall portion.

There is provided an end plate that includes a through hole that causes an outer wall portion and an inner wall portion to communicate with each other, into which an intruding portion provided in a wheel-side member can intrude, a first press-formed portion formed by depressing in a peripheral edge of the through hole in the inner wall portion. The end plate includes a second press-formed portion arranged in a part of a peripheral edge on the side of a peripheral end of the inner wall portion, which is a remnant of a portion where the first press-formed portion is arranged in the inner wall portion, and formed therein with a protruding portion by protruding a part of the peripheral edge, and a screw hole formed by penetrating through the protruding portion in the second press-formed portion between the outer wall portion and the inner wall portion.

In a pressing step, a first forged product is pressed by a first die, and thereby, a second forged product including a rough flange having a thickness-changing portion is produced. The thickness-changing portion includes a front part protruding frontward from a side of a rough web part and a rear part protruding rearward from the side of the rough web part. Each of the front part and the rear part includes a first part, and a second part that is thicker than the first part and is located farther from the rough web part than the first part. In the pressing step, at least a part of the rough flange that is above or below the web part (thick part) is pressed by the first die, whereby the material of the first forged product in the part is caused to flow frontward and rearward, and the thickness-changing portion is formed.

The production method includes a first step, a second step and a third step. In the first step, a steel material is forged by dies, whereby a forged product including a rough web part and four plate-shaped rough flange parts is produced. In the second step, at least one specified rough flange part, which is at least one of the four rough flange parts, is pressed by a first die, whereby a first bent portion bending outward in an up-down direction is formed in the specified rough flange part. In the third step, the edge of the first bent portion is pressed by a second die inward in the up-down direction, whereby the edge is deformed and a second bent portion is formed. In the third step, the edge of the specified flange part is deformed while the edge is kept from deforming in a front-rear direction.