JP7294355B2 - Press molding method and press molding die - Google Patents

Description

The present invention relates to a method of press-molding a press-molded member and a press-molding die used for the press-molding.

Most automobile parts are manufactured by press forming metal sheets. In recent years, higher-strength metal sheets have been adopted for automobile parts in order to achieve both weight reduction of the vehicle body and collision safety. As such a press-formed product for automobiles, there is a press-formed member having a U-shaped cross-section as shown in FIG. 1(a) or a press-formed member having a hat-shaped cross-section as shown in FIG. 1(b). Such press-molded members are manufactured by form molding (bending molding) or draw molding (drawing molding).

In particular, when forming a U-shaped cross-sectional press-formed member or a hat cross-sectionally-shaped press-formed member having a long vertical wall portion and a high forming height of the formed member, the warpage of the vertical wall portion becomes large if it is performed in one step. Generally, molding is performed in a plurality of steps because the shape deviates greatly from the target shape. That is, as shown in FIG. 2(a), first, in the first step, after forming a press-formed member 30 having a hat cross-sectional shape with a relatively low forming height _h1 , the second step shown in FIG. 2(b) , the flange portion is bent back to form a press-formed member 40 having a desired forming height _h2 .

However, when the flange portion is bent back in the second step, it is not flattened back, and as shown in FIG. do. In particular, it is noticeable in high-strength steel sheets exceeding 440 MPa class and having a thickness of 1.0 mm or more. Here, as shown in FIG. 3B, as an index for quantitatively evaluating the magnitude of the bending habit 10, the height from the inner plate surface of the vertical wall portion to the tip of the convex portion of the bending habit 10 is measured. The habit height is set to 12.

If such a bending habit 10 remains, as shown in FIG. 4, it becomes difficult to perform resistance spot welding when assembling a flat component to the vertical wall portion. That is, in resistance spot welding, the vertical wall portion 14 and another flat part 16 are superimposed and sandwiched with electrodes 18 while applying pressure from both sides, and a large current is applied for a short time to create a welded portion (nugget) 20 between metals. join. However, if the vertical wall portion 14 remains with the bending tendency 10, a gap is generated between the vertical wall portion 14 and the component 16 to be welded facing the vertical wall portion 14, and the current becomes difficult to flow, making welding difficult.

In order to address such a problem, Patent Literature 1 discloses a bend straightening device that straightens a convex, R-shaped bending peculiarity formed in a sheet metal. In Patent Document 1, a punch having a first bending portion having three first convex portions arranged side by side at a predetermined interval and two concave forming spaces formed in the first bending portion are arranged to face each other. By using a die having a second bending part having two second convex parts that are formed by bending, a small deformation is applied locally to correct the bending tendency of the press-formed product.

JP 2013-103226 A

However, in the method described in Patent Literature 1, in addition to the step of forming the press-formed product, there is a problem that a step of correcting the bending tendency using special press equipment is added. The present invention is intended to solve such problems, and a press forming method that can make the height of the bending habit of a press-formed product lower than before without adding a step of correcting the bending habit, and a method for use in the press molding. It is an object of the present invention to provide a press molding die that can be

Means for solving the above problems are as follows.
[1] A top plate portion, a vertical wall portion continuous from both ends of the top plate portion and inclined with respect to the top plate portion, and a flange portion continuous from the lower end of the vertical wall portion via a curved surface portion. A press-forming method in which the flange portion of a press-formed member having a hat cross section is bent back to form a vertical wall portion, wherein the upper surface supporting the top plate portion and the press-forming so as to spread downward from the upper surface The press forming member is attached to a punch having two inclined surfaces inclined from the direction, and the side surfaces facing each of the two inclined surfaces of the punch and inclined at the same angle as the inclined surfaces of the opposing punch. are moved in the press forming direction and also in the direction away from the punch, and the vertical distance between the side surface of the die and the inclined surface of the punch is kept constant to form the flange portion A press molding method that bends back.
[2] The press molding method according to [1], wherein the clearance between the inclined surface of the punch and the side surfaces of the two dies satisfies the following formula (1).
0%≦clearance≦50% (1)
The clearance in the formula (1) is calculated by subtracting the plate thickness of the vertical wall portion from the vertical distance between the inclined surface of the punch and the side surfaces of the two dies, dividing by the plate thickness, and multiplying by 100. is the value (%)
[3] A top plate portion, a vertical wall portion continuous from both ends of the top plate portion and inclined with respect to the top plate portion, and a flange portion continuous from the lower end of the vertical wall portion via a curved surface portion. A press-forming die for use in press-forming a vertical wall portion by bending back the flange portion of a press-formed member having a hat cross-sectional shape, wherein the press-forming die has a lower die and an upper die , the lower mold has an upper surface for supporting the top plate portion, and a punch having two inclined surfaces inclined from the press molding direction so as to spread downward from the upper surface; moves two dies having side surfaces facing the two inclined surfaces of the punch and inclined at the same inclination angle as the inclined surfaces of the punch, and moving each of the two dies in a direction away from the punch. and an upper support base for supporting the two dies, wherein the two dies move in the press forming direction while maintaining a constant vertical distance between the side surfaces of the two dies and the inclined surface of the punch. molding die.
[4] The press molding die according to [3], wherein the clearance between the inclined surface of the punch and the side surfaces of the two dies satisfies the following formula (1).
0%≦clearance≦50% (1)
The clearance in the formula (1) is calculated by subtracting the plate thickness of the vertical wall portion from the vertical distance between the inclined surface of the punch and the side surfaces of the two dies, dividing by the plate thickness, and multiplying by 100. is the value (%)

According to the present invention, it is possible to manufacture a press-formed member having a low bending habit height without adding a step of correcting the bending habit. This makes it possible to easily perform resistance spot welding when assembling a flat component to the vertical wall portion, maintain a high bonding strength, and suppress a decrease in productivity of the press-formed member.

It is a perspective view of a press-formed member (U-shaped cross-sectional shape, hat cross-sectional shape). It is a schematic diagram explaining the method to shape|mold U-shaped cross-sectional shape from hat cross-sectional shape. It is a schematic diagram explaining a bending habit and bending habit height. It is a schematic diagram explaining the resistance spot welding of the member which has a bending habit, and a flat component. 1 is a perspective view of a press-molding die 100 as an example used in the press-molding method according to the present embodiment; FIG. It is a cross-sectional view showing a press-formed member 30 having a hat cross-sectional shape. FIG. 2 is a cross-sectional view showing the press-molding die 100 in a mold-opened state before press-molding. 4 is a cross-sectional view showing the press-molding die 100 in a state at the start of press-molding in which the tips of the dies 66 and 68 are in contact with the flange portion 36 of the hat cross-sectional member; FIG. FIG. 3 is a cross-sectional view showing the press-molding die 100 in a state of reaching the bottom dead center of molding; FIG. 3 is a cross-sectional view showing the press-molding die 100 in a mold-opened state after press-molding. FIG. 2 is an enlarged cross-sectional view showing the press-molding die 100 in a state of reaching the bottom dead center of molding; It is a cross-sectional schematic diagram explaining the condition which bends back the flange part 36 immediately after press-forming start. FIG. 3 is a perspective view of a press-molding die 110 as another example used in the press-molding method according to the present embodiment. FIG. 3 is a cross-sectional view showing the press-molding die 110 in a mold-opened state before press-molding. 3 is a cross-sectional view showing the press-molding die 110 in a state at the start of press-molding in which the tips of the dies 73 and 75 are in contact with the flange portion 36. FIG. FIG. 4 is a cross-sectional view showing the press-molding die 110 in a state of reaching the bottom dead center of molding; FIG. 3 is a perspective view of a press-molding die 120 as another example used in the press-molding method according to the present embodiment.

Hereinafter, the present invention will be described through embodiments of the present invention. FIG. 5 is a perspective view of a press-molding die 100 as an example used in the press-molding method according to this embodiment. The press molding die 100 has at least an upper die 60 and a punch 86 . The upper mold 60 has at least an upper support 62 and two dies 66 , 68 . In the press-molding method according to the present embodiment, the upper die 60 is moved in the press-molding direction in a state in which the press-molded member 30 having a hat cross-sectional shape formed linearly in the longitudinal direction is mounted on the punch 86, and the upper die 60 and the punch 86 are relatively moved to bend back the flange portion 36 of the press forming member 30 to perform press forming to form a vertical wall portion. As a result, the press-formed member 40 having a U-shaped cross section with a high forming height is obtained.

FIG. 6 is a cross-sectional view showing a press-formed member 30 having a hat cross-sectional shape. As shown in FIG. 6 , the press-formed member 30 having a hat cross-sectional shape includes a top plate portion 32 and vertical walls that are continuous from both ends of the top plate portion 32 via curved surface portions 33 and that are inclined with respect to the top plate portion 32 . and a flange portion 36 continuous from the lower end of the vertical wall portion 34 via a curved surface portion 35 .

FIG. 7 is a cross-sectional view showing the press-molding die 100 in an opened state before press-molding. The cross-sectional views shown in FIGS. 7 to 10 are cross-sectional views of the B cross section in FIG. The upper support table 62 of the upper mold 60 supports the dies 66 and 68 so as to be movable in the direction separating from the punch 86 (the X direction in FIG. 7). A pad 72 may be provided on the upper support table 62 so as to be movable in the press forming direction, and the top plate portion 32 of the press forming member 30 may be pressed during press forming.

The punch 86 is a convex mold having an upper surface 87 that supports the top plate portion 32 of the press-molded member 30, and inclined surfaces 88 and 89 that continue from both ends of the upper surface 87 and are inclined to spread downward. (lower mold). The angle (θ1) of the inclined surfaces 88 and 89 with respect to the press molding direction is preferably about 1 to 5°.

The die 66 has a side surface 67 that is inclined at the same angle as the inclined surface 88 of the punch 86 facing it during press molding. The die 68 also has a side surface 69 inclined at the same angle as the inclined surface 89 of the punch 86 facing it during press molding.

FIG. 8 is a cross-sectional view showing the press-molding die 100 in a state at the start of press-molding in which the tips of the dies 66 and 68 are in contact with the flange portion 36 of the hat cross-sectional member. When the upper die 60 moves in the press-forming direction from the state shown in FIG. 7, the dies 66 and 68 also move away from the punch 86 while moving in the press-forming direction. In this manner, the dies 66 and 68 move in the same oblique direction while maintaining a constant vertical distance from the opposing oblique surfaces 88 and 89 and abut the flange portion 36 . At this time, in order to maintain a constant vertical distance between the inclined surfaces 88, 89 of the punch 86 and the side surfaces 67, 69 of the dies 66, 68, the inclined side surfaces 67, 69 of the dies 66, 68 are positioned opposite to each other. A cylinder or the like may be provided on the side outer surfaces 70, 71 to move the dies 66, 68 away from the punch 86 in correspondence with the movement in the press forming direction.

In the mold provided with the pad 72 , the dies 66 and 68 contact the upper surface of the top plate portion 32 of the press forming member 30 before contacting the flange portion 36 , and the top plate portion 32 contacts the upper surface 87 of the punch 86 . is pressed with a predetermined biasing force. Thereby, swinging of the press-molding member 30 is suppressed, and press-molding can be performed stably.

FIG. 9 is a cross-sectional view showing the press-molding die 100 in a state of reaching the bottom dead center of molding. When the upper die 60 moves further in the press molding direction from the state shown in FIG. 8, the dies 66 and 68 move the flange portions in the same direction of inclination as the inclined surfaces while maintaining a constant vertical distance from the inclined surfaces 88 and 89. 36 is bent and then the bottom dead center of the forming is reached. In this state, the flange portion 36 of the press-formed member 30 is bent back, and a press-formed member 40 having a U-shaped cross section with a high forming height is manufactured.

FIG. 10 is a cross-sectional view showing the press-molding die 100 in an opened state after press-molding. After reaching the molding bottom dead center, the upper die 60 is relatively moved away from the punch 86 and raised to the position shown in FIG. In this state, the press-formed member 40 is taken out.

FIG. 11(a) is an enlarged cross-sectional view showing the press-molding die 100 in a state of reaching the bottom dead center of the molding. The vertical distance L between the inclined surface 89 of the punch 86 and the side surface 69 of the die 68 at the bottom dead center of forming is determined by the dimensional accuracy required for the press-formed member 40 to be manufactured. If a line extending from the side surface 69 of the die 68 intersects with the lower surface of the die 68 as a reference point 94, in the conventional press molding method, the die 68 is integrated with the upper support 62 as shown in FIG. 11(b). Since the die 68 was moved in the press-forming direction while the die 68 was being pressed, the punch 86 and the die 68 were inclined at the start of press-forming, so the vertical distance L between them reached the forming bottom dead center. It turns out that it takes longer than the time. Therefore, when the die 68 and the flange portion 36 come into contact with each other, the vertical distance L between the inclined surface 89 of the punch 86 and the side surface 69 of the die 68 when the flange portion 36 is bent back is at the bottom dead center of the forming process. is longer than the corresponding vertical distance of .

FIG. 12 is a schematic cross-sectional view illustrating how the flange portion 36 is bent back immediately after the start of press forming. As shown in FIG. 12, when the flange portion 36 is bent back, along with the deformation of the curved surface portion 35, the front and rear portions 38 and 39 of the curved surface portion 35 of the press-formed member 30 move in the curvature direction of the curved surface portion 35 ( It bends and deforms in the opposite direction (concave on the punch 86 side) to the convex on the punch 86 side. At this time, if the vertical distance L between the inclined surface 89 of the punch 86 and the side surface 69 of the die 68 is long, there is a space for free deformation, so that the bending deformation in the opposite direction increases, resulting in a high bending habit. was occurring. On the other hand, in the press molding method according to the present embodiment, the dies 66 and 68 are moved in the press molding direction and moved away from the punch 86 so that the sides 67 and 69 of the dies 66 and 68 and the punch 86 are separated from each other. Since the dies 66, 68 are moved in the direction of the inclination of the punch 86 while maintaining a constant vertical distance from the inclined surfaces 88, 89, the inclined surface of the punch 86 during press molding is The vertical distance between 89 and the side face 69 of the die 68 remains the same at the start of press molding and at the bottom dead center of the molding. For this reason, the vertical distance L between the inclined surface 89 of the punch 86 and the side surface 69 of the die 68 at the time of starting the press molding of the present embodiment is shorter than that of the conventional press molding method, and the space that can be freely deformed is narrowed. . As a result, the bending deformation in the opposite direction at the front and rear portions 38 and 39 of the curved surface portion 35 is reduced immediately after the start of press-forming, and the press-formed member 40 with a low bending habit height 12 is manufactured. Thus, by carrying out the press-forming method according to the present embodiment, it is possible to manufacture a press-formed member having a low bending height without adding a conventional step of correcting the bending. As a result, when assembling a flat part to the vertical wall portion, resistance spot welding can be easily performed, a high joint strength can be maintained, and a decrease in productivity of the press-formed member can be suppressed.

Furthermore, the clearance between the inclined surfaces 88, 89 of the punch 86 and the side surfaces 67, 69 of the dies 66, 68 preferably satisfies the following formula (1).

0%≦clearance≦50% (1)
The clearance (%) in the above formula (1) is calculated from the vertical distance L between the inclined surfaces 88, 89 of the punch 86 and the side surfaces 67, 69 of the dies 66, 68 (see FIG. 11(a)). It is a value ((L−t)/t)×100 calculated by subtracting the plate thickness t of the vertical wall portion 34, dividing by the plate thickness t, and multiplying by 100.

If the clearance is less than 0%, the thickness of the press-formed member becomes smaller than the thickness of the press-formed member, so press-forming becomes a so-called "ironing process", and scratches such as "galling" and abrasion occur in the vertical wall portion 34 and the flange portion 36. I don't like it. On the other hand, when the clearance is wider than 50%, the distance between the inclined surfaces 88, 89 of the punch 86 and the side surfaces 67, 69 of the dies 66, 68 becomes too wide, and the dimensional variation of the manufactured press-formed member 40 becomes large. I don't like it.

Furthermore, in the press-molding method according to the present embodiment, an example in which the press-molded member 30 having the hat cross-sectional shape is press-molded to produce the press-molded member 40 having the U-shaped cross-sectional shape has been described. The member 30 may be press-formed to produce a shaped member having a hat profile with a high forming height. In this case, the lower surfaces of the dies 66 and 68 may be used to press-form the flange portions in the same manner as in conventional press-forming.

Next, examples of other molds used in the press molding method of the present embodiment will be described. FIG. 13 is a perspective view of a press molding die 110 as another example used in the press molding method according to this embodiment.

FIG. 14 is a cross-sectional view showing the press-molding die 110 in an opened state before press-molding. The cross-sectional views shown in FIGS. 14 to 16 are cross-sectional views of the C cross section in FIG. The press molding die 110 has an upper die 61 and a lower die 81 . An upper support table 62 of the upper mold 61 supports the dies 73 and 75 so as to be movable in a direction away from the punch 84 . Each of the dies 73,75 has a first guide surface 74,76 extending from the tip of the dies 73,75, respectively. The inclination angle (θ2) of the first guide surfaces 74, 76 is the same as the angle of the inclination surfaces 95, 96 of the punch 84 with respect to the press forming direction.

The lower die 81 has a lower support base 82 and a punch 84 . The lower support base 82 has second guide surfaces 90 and 91 at both ends in the width direction. The inclination angle (θ2) of the second guide surfaces 90, 91 is the same as the angle of the inclination surfaces 95, 96 of the punch 84 with respect to the press forming direction. In this manner, the press molding die 110 has first guide surfaces 74, 76 and second guide surfaces 90, 91, which engage with each other to move the upper die 61 in the press molding direction. As it moves, the dies 73 and 75 move in the press forming direction and also move away from the punch 84 . In this manner, the dies 73 and 75 are arranged to maintain a constant vertical distance between the side surfaces 77 and 78 of the dies 73 and 75 and the inclined surfaces 95 and 96 of the punch 84 in the direction of inclination of the opposing inclined surfaces 95 and 96 of the punch 84 . You can hold and move. It should be noted that in order to maintain a constant vertical distance between the slanted surfaces 95, 96 of the punch 84 and the side surfaces 77, 78 of the dies 73, 75, the outer surfaces of the dies 73, 75 opposite the slanted side surfaces 77, 78 are The 70 and 71 may be pressed in the direction of the punch 84 with biasing force by springs, cylinders, or the like.

FIG. 15 is a cross-sectional view showing the press-molding die 110 in a state at the start of press-molding in which the tips of the dies 73 and 75 are in contact with the flange portion 36. As shown in FIG. As the upper mold 61 moves further in the press molding direction, the dies 73, 75 move in the direction of inclination of the inclined surfaces 95, 96 due to engagement with the first guide surfaces 74, 76 and the second guide surfaces 90, 91. The sides 77, 78 of the dies 73, 75 and the inclined surfaces 95, 96 of the punch 86 are moved at a constant vertical distance.

FIG. 16 is a cross-sectional view showing the press-molding die 110 having reached the bottom dead center of the molding. As the upper die 61 moves further in the pressing direction, the engagement of the first guide surfaces 74, 76 and the second guide surfaces 90, 91 causes the dies 73, 75 to have the same inclination as the opposing inclined surfaces 95, 96. It moves further in the angular direction and reaches the forming bottom dead center.

FIG. 17 is a perspective view of a press-molding die 120 as another example used in the press-molding method according to this embodiment. A press-molding die 120 shown in FIG. 17 has a die structure in which the press-molding die 100 and the press-molding die 110 are combined. A region D of the press molding die 120 is a press molding region. A press-formed member 30 is attached to the punch 140 in the area D. As shown in FIG. The dies 130 and 132 of the upper mold 121 in the region D are not provided with a shape corresponding to the first guide surfaces 74 and 76 . Similarly, the lower support base 144 of the lower mold 122 in the region D is not provided with a shape corresponding to the second guide surface.

On the other hand, areas E and F of the press molding die 120 are positioning areas that are not involved in press molding, and the press molding member 30 is not attached to the punches 140 in the areas E and F. The dies 130 , 132 in the regions E, F are provided with the same shape as the first guide surfaces 74 , 76 in the press molding die 110 . Similarly, the lower support base 144 in regions E and F has the same shape as the second guide surfaces 90 and 91 . Therefore, the G cross-sectional shape of the press molding die 120 is the same cross-sectional shape as the cross-sectional view shown in FIG. 14 .

With such a mold structure, when the upper mold 121 moves in the press molding direction, the dies 130 and 132 move in the direction of inclination of the inclined surfaces 141 and 142 of the punch 140 facing each other. , 133 and the inclined surfaces 141 and 142 of the punch 140 can be moved while maintaining a constant vertical distance. In addition, since the first guide surface is not provided in the molding regions 130 and 132, a press-molded member having a hat cross-sectional shape having a long flange portion 36 is used to form a U-shaped cross-sectional shape with a high molding height. A press-formed member can be press-formed.

Next, using CAE analysis by the finite element method, a press-molded member having a hat cross-sectional shape is press-molded into a high-height, U-shaped cross-sectional molded product using a press-molding die 100 shown in FIGS. A press-molding analysis was performed to confirm the effect of the press-molding method according to the present embodiment. For the press forming, a press formed member having a hat cross-section made of a cold-rolled steel sheet having a plate thickness of 1.2 mm and a tensile strength of 1180 MPa class was used. The dimensions of the press-formed member having the shape of a hat cross-section are as follows: the width of the top plate portion is 50 mm, the length of the vertical wall portion is 50 mm, and the length of the flange portion is 50 mm. Further, the top plate portion and the vertical wall portion, and the vertical wall portion and the flange portion are connected by a curved surface portion having a curvature radius of 10 mm.

The width of the top surface of the punch and the pad was 50 mm, the length of the inclined surface of the punch was 120 mm, and the angle of inclination of the two inclined surfaces with respect to the press forming direction was 3°. In addition, the angle of inclination of the side surfaces of the two dies with respect to the press molding direction was also set to 3°. A curved surface portion with a radius of curvature of 10 mm is provided at the lower end of each side surface of the two dies. Using such a press-molding member and a press-molding die, changing the vertical distance between the inclined surface of the punch and the side surface of the die at the moving direction of the die and the bottom dead center of the molding is defined by the above formula (1) The press-forming analysis was performed while changing the clearance, and the height of the bending habit of the press-formed member formed under each condition was obtained. Table 1 below shows the results of the direction of movement of the die, the clearance at the bottom dead center of the forming defined by the formula (1), and the height of the bending habit. In addition, the height of the bending tendency was set to the height 12 shown in FIG.3(b).

As shown in Examples 1 to 4 in Table 1, when the direction of movement of the die is 3°, which is the inclination angle of the inclined surface of the punch, and the vertical distance between the inclined surface of the punch and the side surface of the die is constant, the height of the bending habit is became low. Further, Comparative Example 1, in which the movement direction was inclined by 1° with respect to the press forming direction and the clearance was changed, had a high bending habit height. Furthermore, it was confirmed that by keeping the vertical distance between the punch inclined surface and the die side surface constant, the height of the bending habit can be significantly reduced compared to Conventional Examples 1 and 2 in which the die is moved in the press forming direction.

On the other hand, focusing on the clearance defined by the formula (1), the smaller the clearance, the lower the height of the bending habit, and it was confirmed that the smaller the clearance between the punch and the die at the bottom dead center of forming, the better. When the clearance was negative, galling occurred during press molding (Comparative Example 2), which was a problem. From these results, it is confirmed that by bending back the flange portion using the press-forming method according to the present embodiment, a press-formed member with a low bending height can be manufactured without adding a step of correcting the bending habit. was done.

Similarly, using CAE analysis by the finite element method, press-molding analysis of press-molding a hat-shaped press-molded member to a hat-shaped press-molded member with a high molding height using a press molding die 110 shown in FIGS. The result of performing the above will be described as Example 2. For the press forming, a press-formed member having a hat cross section made of a hot-rolled steel sheet having a thickness of 3.0 mm and a tensile strength of 980 MPa was used. The dimensions of the press-formed member having the shape of a hat cross-section are as follows: the width of the top plate portion is 50 mm, the length of the vertical wall portion is 50 mm, and the length of the flange portion is 50 mm. Further, the top plate portion and the vertical wall portion, and the vertical wall portion and the flange portion are connected by a curved surface portion having a radius of curvature of 10 mm.

This press-formed member was press-formed to produce a hat-shaped press-formed member having a top plate portion with a width of 50 mm, a vertical wall portion with a length of 80 mm, and a flange portion with a width of 20 mm. The width of the upper surface of the punch was 50 mm, the length of the inclined surface of the punch was 100 mm, and the angle of inclination of the two inclined surfaces with respect to the press forming direction was 5°. In addition, the angle of inclination of the side surfaces of the two dies with respect to the press molding direction was also set to 5°. A curved surface portion with a radius of curvature of 10 mm is provided at the lower end of each side surface of the two dies. Also in this press forming analysis, the direction of movement of the die and the clearance at the forming bottom dead center defined by formula (1) were changed, and the bending tendency height of the press formed member with a hat cross-sectional shape formed under each condition was obtained. . Table 2 below shows the results of the direction of movement of the die, the clearance at the bottom dead center of the forming defined by the formula (1), and the height of the bending habit.

As shown in invention examples 11 and 12 in Table 2, by setting the moving direction of the die to 5°, which is the inclination angle of the inclined surface of the punch, the die is moved in the press forming direction like conventional example 11. The bending habit height was lower than Further, by narrowing the clearance, the height of the bending tendency of the press-formed member was lowered, and these tendencies were the same as the results shown in Table 1. From these results, it was found that even if the press-formed member manufactured by press-forming has a hat cross-sectional shape, the height of the bending habit can be reduced in the same manner as the result of the U-shaped cross-sectional shape.

REFERENCE SIGNS LIST 10 bending habit 12 bending habit height 14 vertical wall portion 16 component 18 electrode 20 welded portion 30 hat cross-sectional press-formed member 32 top plate portion 33 curved surface portion 34 vertical wall portion 35 curved surface portion 36 flange portion 40 U-shaped cross-sectional shape 60 upper mold 61 upper mold 62 upper support base 66 die 67 side surface 68 die 69 side surface 70 outer surface 71 outer surface 72 pad 73 die 74 first guide surface 75 die 76 first guide surface 77 side surface 78 side surface 81 lower mold 82 lower support base 84 punch 86 punch 87 upper surface 88 inclined surface 89 inclined surface 90 second guide surface 91 second guide surface 94 point 95 inclined surface 96 inclined surface 100 press mold 110 press mold 120 press molding die 121 upper die 122 lower die 130 die 131 side face 132 die 133 side face 140 punch 141 inclined surface 142 inclined surface 144 lower support base

Claims (4)

A cross-section of a hat having a top plate portion, a vertical wall portion continuing from both ends of the top plate portion and inclined with respect to the top plate portion, and a flange portion continuing from a lower end of the vertical wall portion via a curved surface portion. A press-forming method in which the flange portion of the shaped press-formed member is bent back to form a vertical wall portion,
mounting the press-forming member on a punch having an upper surface for supporting the top plate portion and two inclined surfaces inclined from the press-forming direction so as to spread downward from the upper surface;
Two dies facing each of the two inclined surfaces of the punch and having side surfaces inclined at the same angle as the inclined surfaces of the opposing punch are moved in the press forming direction and also in the direction away from the punch. A press forming method in which the vertical distance between the side surface of the die and the inclined surface of the punch is kept constant while the flange portion is bent back. 2. The press molding method according to claim 1, wherein the clearance between the inclined surface of the punch and the side surfaces of the two dies satisfies the following formula (1).
0%≦clearance≦50% (1)
The clearance in the formula (1) is calculated by subtracting the plate thickness of the vertical wall portion from the vertical distance between the inclined surface of the punch and the side surfaces of the two dies, dividing by the plate thickness, and multiplying by 100. is the value (%) A cross-section of a hat having a top plate portion, a vertical wall portion continuing from both ends of the top plate portion and inclined with respect to the top plate portion, and a flange portion continuing from a lower end of the vertical wall portion via a curved surface portion. A press molding die used for press molding in which the flange portion of a shaped press molding member is bent back to form a vertical wall portion,
The press molding die has a lower die and an upper die,
The lower die has a punch having an upper surface that supports the top plate portion and two inclined surfaces that are inclined from the press molding direction so as to spread downward from the upper surface,
The upper mold includes two dies having side surfaces that face the two inclined surfaces of the punch and are inclined at the same angle as the inclined surfaces of the punch, and separates the two dies from the punch. and an upper support base that supports movably in the direction of
The press molding die, wherein the two dies move in the press molding direction while maintaining a constant vertical distance between the side surfaces of the two dies and the inclined surface of the punch. 4. The press molding die according to claim 3, wherein the clearance between the inclined surface of the punch and the side surfaces of the two dies satisfies the following formula (1).
0%≦clearance≦50% (1)
The clearance in the formula (1) is calculated by subtracting the plate thickness of the vertical wall portion from the vertical distance between the inclined surface of the punch and the side surfaces of the two dies, dividing by the plate thickness, and multiplying by 100. is the value (%)

Images