阅读说明：本技术 冲压成型方法 (Press molding method ) 是由 秋庭弘克 佐野武司 松谷健司 狩野贵之 于 2020-03-03 设计创作，主要内容包括：一种冲压成型方法,将板材(10)成型为包含棱线部(14)的目标成型体(12),该方法包括：第一工序,成型中间成型体(42)；和第二工序,用中间成型体(42)形成目标成型体(12)。目标成型体(12)和中间成型体(42)具有一致区域(46a、46b)和中间区域(44),一致区域位于中间棱线部(44c)的两侧,在一致区域,目标成型体和中间成型体的截面形状一致；在中间区域(44)中,目标成型体和中间成型体的截面形状不一致,中间区域(44)具有外侧区域(44b)和内侧区域(44a),在外侧区域(44b),中间成型体(42)比目标成型体(12)向棱角半径的外侧突出；在内侧区域(44a),中间成型体(42)比目标成型体(12)向棱角半径的内侧弯曲。(A press molding method for molding a plate material (10) into a target molded body (12) including a ridge line portion (14), the method comprising: a first step of molding an intermediate molded body (42); and a second step of forming the target molded body (12) from the intermediate molded body (42). The target molded body (12) and the intermediate molded body (42) have matching regions (46a, 46b) and an intermediate region (44), the matching regions are located on both sides of the intermediate ridge line portion (44c), and the cross-sectional shapes of the target molded body and the intermediate molded body are matched in the matching regions; in the middle area (44), the cross-sectional shapes of the target molded body and the middle molded body are not consistent, the middle area (44) is provided with an outer area (44b) and an inner area (44a), the outer area (44b) is provided with the middle molded body (42) which protrudes to the outside of the corner radius than the target molded body (12); in the inner region (44a), the intermediate molded body (42) is bent inward of the corner radius than the target molded body (12).)

1. A press-forming method for forming a plate material (10) into a target formed body (12) including a ridge line portion (14),

the method comprises the following steps:

a first step of molding an intermediate molded body (42) having an intermediate ridge portion (44c) having a radius larger than a corner radius of the ridge portion; and

a second step of forming a target molded body from the intermediate molded body,

the target molded body and the intermediate molded body have matching regions (46a, 46b) located on both sides of the intermediate ridge line portion, and an intermediate region (44) where the cross-sectional shapes of the target molded body and the intermediate molded body match; in the intermediate region, the cross-sectional shapes of the target molded body and the intermediate molded body are not uniform,

the intermediate region has an outer region (44b) in which the intermediate molded body protrudes more outward than the target molded body in the corner radius, and an inner region (44 a); in the inner region, the intermediate molded body is bent more inward than the target molded body toward the corner radius.

2. The press-forming method according to claim 1,

in the second step, the intermediate molded body in the outer region is moved toward the ridge line portion, thereby compensating for a shortage of length when the inner region is molded into the ridge line portion.

3. The press-molding method according to claim 1 or 2,

the length of the intermediate formed body in the cross-sectional direction in the outer region is longer than the length of the intermediate formed body in the cross-sectional direction in the inner region.

4. The press-forming method according to any one of claims 1 to 3,

the intermediate region of the intermediate molded body is formed of a plurality of arc regions having different curvatures, and has a reference inflection point (48b) as a boundary of the arc regions in the vicinity of a position to be the ridge line part of the target molded body,

the length of the intermediate region on the outer region side with respect to the reference inflection point is greater than the length of the intermediate region on the opposite side to the outer region with respect to the reference inflection point.

5. The press-forming method according to claim 4,

the intermediate region of the intermediate molded body includes: a first arc region curved from one end of the intermediate region to an inner side of the target molded body; and a second arc region connected to the first arc region at the reference inflection point and curved to protrude outward of the target molded body,

the radius of curvature (Rb) of the second circular arc region is greater than the radius of curvature (Ra) of the first circular arc region.

6. The press-forming method according to any one of claims 1 to 5,

a maximum deviation (Ha) in a press stroke direction between the intermediate molded body and the target molded body in the inner region is larger than a maximum deviation (Hb) in the press stroke direction between the intermediate molded body and the target molded body in the outer region.

7. The press-forming method according to any one of claims 1 to 6,

the first step and the second step are performed in a molding die (20, 30) having a pressing plate (24, 34) that holds the peripheral portion (16) of the plate material before the ridge line portion is pressed, and the molding die is configured to perform the first step and the second step

The outer region of the intermediate molded body is formed in a portion closer to the platen than the ridge portion.

8. The press-forming method according to claim 7,

the height of the platen (34) in the second step is set to be higher than the height of the platen (24) in the first step by at least a maximum deviation (Hb) between the intermediate molded body and the target molded body in the press stroke direction in the outer region.

9. The press-forming method according to claim 8,

the length of the peripheral portion (16b) in the second step is set to be longer than the length of the peripheral portion (16b) in the first step.

10. The press-forming method according to any one of claims 1 to 9,

the outer periphery of the plate material is formed into a quadrangle formed by a first side (10a), a second side (10b), a third side (10c) and a fourth side (10d), wherein the second side is opposite to the first side; the third side extends in a direction intersecting the first side; the fourth side is opposite to the third side,

the ridge line portion is formed to extend from the first edge toward the second edge in the vicinity of the third edge and in the vicinity of the fourth edge.

11. The press-forming method according to any one of claims 1 to 10,

the inner region of the intermediate molded body is formed inside the ridge line portion of the target molded body,

the outer region of the intermediate molded body is formed outside the ridge line portion of the target molded body.

Technical Field

The present invention relates to a press-forming method for forming a plate material into a predetermined shape.

Background

Outer panels such as engine covers, side panels, and door panels of automobiles are generally produced by press-molding a metal plate material. The outer panel is a part that determines the appearance of the automobile, and is designed using, for example, a ridge portion having a small radius of curvature called a character line (character line). In the molding of such an outer panel, an advanced press molding technique is required.

German patent application publication No. 102011115219 discloses a press-forming method of a plate material in which a ridge line portion (also referred to as a ridge corner portion) is preformed using a first die and a portion other than the ridge line portion is formed into a final shape, and then the ridge line portion is formed into the final shape using a second die. The radius of curvature (also referred to as a corner radius) of the ridge portion formed by the first die is about 2 to 10 times as large as the final shape, and the ridge portion is formed into a predetermined size by deep drawing with the second die.

Japanese patent laid-open publication No. 5959702 discloses a method of manufacturing a molded article having a ridge line portion by two-stage press working. Japanese patent laid-open publication No. 5959702 discloses a method of preventing wire displacement by setting the intermediate shape formed by the first-stage press working to protrude outward than the target molded body formed by the second-stage press working.

Disclosure of Invention

In the press forming method described in the german patent application publication No. 102011115219, since drawing is performed in two stages, surface distortion is not easily generated. However, when the ridge portion is required to be molded with a small radius of curvature (corner radius), the ridge portion may be cracked. In the press molding method of japanese patent application laid-open No. 5959702, since the second stage molding is performed with the tension removed, surface distortion may occur.

Accordingly, an object of the present invention is to provide a press forming method for forming a ridge line portion having a small radius of curvature by two-stage drawing, which can achieve both suppression of crack generation and suppression of surface distortion.

One aspect of the present invention is a press-forming method of forming a plate material into a target formed body including a ridge line portion, the press-forming method including: a first step of molding an intermediate molded body having an intermediate ridge line portion with a radius larger than a corner radius of the ridge line portion; and a second step of forming a target molded body from the intermediate molded body, the target molded body and the intermediate molded body having a matching region and an intermediate region, the matching region being located on both sides of the intermediate ridge line portion, the target molded body and the intermediate molded body having a matching cross-sectional shape in the matching region; in the intermediate region, the cross-sectional shapes of the target molded body and the intermediate molded body do not match, the intermediate region having an outer region and an inner region, the intermediate molded body protruding outward of the corner radius from the target molded body in the outer region; in the inner region, the intermediate molded body is bent more inward than the target molded body toward the corner radius.

According to the press molding method described above, even when the ridge line portion having a small radius of curvature is molded, both suppression of crack generation and suppression of surface distortion can be achieved.

Drawings

Fig. 1A is a plan view showing an example of a target molded body molded by the press molding method according to the embodiment, and fig. 1B is a cross-sectional view taken along IB-IB in fig. 1A.

Fig. 2 is a cross-sectional view of a first step of the press molding method according to the embodiment.

Fig. 3 is a cross-sectional view of a second step of the press molding method according to the embodiment.

Fig. 4 is a cross-sectional view showing a state in which the intermediate molded body of fig. 2 and the target molded body of fig. 3 are overlapped so that respective regions coincide with each other.

Fig. 5 is a sectional view of the molding die of the second process at a standby position.

Fig. 6 is a sectional view of the molding die of the second process at a blank hold position.

Fig. 7 is a cross-sectional view of the second step in which the molding die is lowered.

Fig. 8 is a sectional view of the molding die of the second process at the lower dead point.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings by way of examples of preferred embodiments. In the following description, the top dead center side in the press stroke direction (press stroke direction) is referred to as "upper side", and the bottom dead center side is referred to as "lower side".

The press molding method according to the embodiment is applied to, for example, an engine hood, a side panel, a door panel, and the like of an automobile. As shown in fig. 1A, a rectangular plate material 10 will be described as an example. The plate material 10 is made of a thin plate made of metal such as steel or aluminum alloy having a thickness of 0.3mm to 3mm, for example. The outer periphery of the plate member 10 is formed in a quadrilateral shape including a first side 10a, a second side 10b opposed thereto, a third side 10c extending in a direction intersecting the first side 10a, and a fourth side 10d opposed to the third side 10 c. As shown in the first step of fig. 2 and the second step of fig. 3, the plate material 10 is press-molded in two stages to obtain the target molded body 12.

The surface of the target molded body 12 shown in fig. 1A is an appearance surface. This external appearance surface corresponds to the surface on the upper side in fig. 1B. As shown in fig. 1A, an edge portion 14 (also referred to as a character line) that is formed in an angular shape in the vicinity of the third side 10c and the fourth side 10d and extends from the first side 10a to the second side 10b is formed on the upper surface of the target molded body 12. As shown in fig. 1B, the ridge portion 14 has a sharp edge-like appearance in which the radius of curvature R (also referred to as a corner radius) in a cross section perpendicular to the direction of the ridge portion 14 is set to 2.5mm to 9 mm.

A first inclined surface 12a is formed on one side of the ridge line portion 14 of the target molded body 12, and a second inclined surface 12b is formed on the other side of the ridge line portion 14. Here, the slope close to the peripheral portion 16 is referred to as a first slope 12a, and the slope far from the peripheral portion 16 is referred to as a second slope 12 b. The first inclined surface 12a and the second inclined surface 12b may be a front surface which is convex when viewed from the front and may be a back surface which is concave when viewed from the front. The angle θ (also referred to as an included angle) formed by the first inclined surface 12a and the second inclined surface 12b can be set as appropriate within a range of 120 ° to 175 °.

A peripheral portion 16 that is finally cut out is formed around the target molded body 12 (region B1). The peripheral portion 16 has: a first peripheral portion 16a formed in a region B3 held by pressure plates (blank holders) 24, 34 (see fig. 2 and 3); and a second peripheral portion 16B formed in a region B2 supported by the lower dies 22, 32.

In the first step shown in fig. 2, the intermediate formed body 42 is press-molded from the plate material 10 using the first upper die 26 and the first lower die 22. As shown in the drawing, the molding die 20 used in the first step includes: a platen 24 disposed in a region B3 below the first peripheral portion 16a of the plate material 10; a first lower die 22 disposed in regions B1, B2 inside the platen 24; and a first upper die 26 disposed above the first lower die 22 and the platen 24.

In the first step, the plate material 10 is first carried into the space between the first lower die 22 and the first upper die 26 and between the platen 24. After that, the first upper die 26 is lowered, and the plate material 10 is pressed by the first lower die 22 and the first upper die 26 while the first peripheral portion 16a is held by the platen 24 and tension is generated, thereby forming the intermediate formed body 42. Further, the first step is not necessarily drawing.

Thereafter, in a second step shown in fig. 3, the target molded body 12 is press-molded from the intermediate molded body 42. As shown in the drawing, the molding die 30 used in the second step includes: a platen 34 disposed in a region B3 below the first peripheral portion 16 a; a second lower die 32 disposed in regions B1, B2 inside the platen 34; and a second upper die 36 disposed above the second lower die 32 and the platen 34.

In the second step, the intermediate molded body 42 is carried into the space between the second lower die 32 and the second upper die 36 and the platen 34. After that, the second upper die 36 is lowered, and the intermediate molded body 42 is pressed by the second lower die 32 and the second upper die 36 while the first peripheral portion 16a is held by the platen 34 and tension is generated, thereby forming the target molded body 12.

As shown in fig. 4, when the intermediate molded body 42 and the target molded body 12 are superposed, an intermediate region 44 having a shape different between the intermediate molded body 42 and the target molded body 12 is formed in a portion indicated by a broken line. The peripheral portion 16 of the intermediate molded body 42 and the peripheral portion 16 of the target molded body 12 are also different in shape. On the other hand, matching regions 46a and 46b are formed on both sides of the intermediate ridge line portion 44c of the intermediate molded body 42, and the shapes of the intermediate molded body 42 and the target molded body 12 match in the matching regions 46a and 46 b.

When focusing on the intermediate region 44 of the intermediate formed body 42, the intermediate region 44 has: an inner region 44a in which the intermediate formed body 42 is bent downward (inward of the corner radius) in the press stroke direction than the target formed body 12; and an outer region 44b in which the intermediate formed body 42 protrudes upward (outward of the corner radius) in the press stroke direction than the target formed body 12. The inner region 44a is formed in a range from an inflection point 48a of the second slope 12b to an intersection 48c of the intermediate formed body 42 and the first slope 12 a. The outer region 44b is formed in a range from an intersection 48c of the intermediate formed body 42 and the first slope 12a to an inflection point 48 e. As shown, the length of the outer region 44b is formed longer than the length of the inner region 44 a.

The cross-sectional shape of the intermediate region 44 of the intermediate molded body 42 is formed by a plurality of circular arc regions. In the illustrated example, the range from the inflection point 48a to the reference inflection point 48b is formed by a first arc region having a curvature radius Ra. The range from the reference inflection point 48b to the inflection point 48d is formed by a second arc region having a curvature radius Rb. The range from the inflection point 48d to the inflection point 48e is constituted by a 3 rd arc region having a curvature radius Rc at the center on the outer side. The range from the inflection point 48a to the reference inflection point 48b and the range from the reference inflection point 48b to the inflection point 48d may be configured by a plurality of arc regions having the same degree of curvature. The third arc region may be absent, and the second arc region may extend from the reference inflection point 48b to the inflection point 48 e.

In the intermediate molded body 42 of the intermediate region 44, the radius of curvature Rb of the second circular arc region is larger than the radius of curvature Ra of the first circular arc region. The radius of curvature Ra of the first circular arc region may be, for example, 15mm to 30mm, the radius of curvature Rb of the second circular arc region may be, for example, 40mm to 60mm, and the radius of curvature Rc of the third circular arc region may be 40mm or more. The length of the outer region 44b may be set as appropriate according to the size of the radius of curvature Rc of the 3 rd circular arc region.

A reference inflection point 48b between the first circular arc region and the second circular arc region is formed in the vicinity of the ridge line portion 14 of the target molded body 12, and the vicinity of the reference inflection point 48b is an intermediate ridge line portion 44c of the intermediate molded body 42 that protrudes most upward in the press stroke direction. As shown in the partially enlarged view, a length between the inflection point 48a and the reference inflection point 48b along the cross-sectional direction of the intermediate formed body 42 is represented by l. A length between the reference inflection point 48b and the inflection point 48e along the cross-sectional direction of the intermediate molded body 42 is denoted by L. In the present embodiment, the intermediate formed body 42 is formed so as to satisfy the relationship of L < L. Although not particularly limited, the length L may be 70mm or less, for example.

The cross-sectional shape of the intermediate molded body 42 is preferably formed such that the elongation ((L1-L0)/L0) is 0 to 2% when the length of the cross-section of the intermediate molded body 42 along the intermediate region 44 is L0 and the length of the cross-section of the target molded body 12 along the intermediate region 44 is L1. The elongation can be adjusted by the shape of the outer region 44b of the intermediate molded body 42.

When the maximum deviation of the portion of the inner region 44a where the deviation between the target formed body 12 and the intermediate formed body 42 in the press stroke direction (the vertical direction in the drawing) is the largest is Ha and the maximum deviation of the portion of the outer region 44b where the deviation between the target formed body 12 and the intermediate formed body 42 in the press stroke direction is the largest is Hb, the intermediate formed body 42 is formed so as to satisfy Ha > Hb. The maximum deviation Ha can be set to, for example, 3.1mm or less, and the maximum deviation Hb can be set to the maximum deviation Ha or less.

On the other hand, when the regions B2, B3 forming the peripheral portion 16 are looked at, the first peripheral portion 16a of the intermediate molded body 42 is formed at a position higher than the first peripheral portion 16a of the target molded body 12 by Hd in the press stroke direction. The height deviation Hd is provided to prevent the intermediate molded body 42 in the intermediate region 44 from being deformed by abutting against the second upper die 36 when the intermediate molded body 42 is held by the platen 34 in the second step (see fig. 6). Therefore, the intermediate formed body 42 is preferably formed so that the variation Hd in the press stroke direction of the first peripheral portion 16a is larger than the maximum variation Hb in the outer region 44 b.

The second peripheral portion 16B of the region B2 is provided to absorb the deviation Hd in the press stroke direction between the first peripheral portion 16a of the intermediate formed body 42 and the first peripheral portion 16a of the target formed body 12 in the range up to the matching region 46B. The length L of the second peripheral portion 16b of the intermediate formed body 42 is set so as not to stretch the intermediate region 44 in the second step_1stAnd the length L of the second peripheral portion 16b of the target molded body 12_2ndThe lengths are set to be substantially the same. In addition, in order to adjust the stretching in the second step, the length L of the second peripheral portion 16b of the objective molded body 12 may be set to be equal to_2ndIs longer than the length L of the second peripheral portion 16b of the intermediate formed body 42_1stLong. L is_2nd-L_1stThe value of (d) may be, for example, about 0 to 0.05 mm.

Next, the operation of the intermediate molded body 42 will be described together with the press molding in the second step with reference to fig. 5 to 8.

As shown in fig. 5, in the initial state, the platen 34 protrudes a predetermined height above the second lower die 32 in the press stroke direction. The platen 34 is configured to be displaceable and stop at a lower end position indicated by a two-dot chain line by being pressed downward by the second upper die 36.

As shown in the drawing, the intermediate molded body 42 is carried into the space between the second lower die 32 and the platen 34 and the second upper die 36. Then, the first peripheral portion 16a is disposed on the platen 34 and positioned.

Thereafter, as shown in fig. 6, when the second upper die 36 is gradually moved downward, the second upper die 36 abuts against the platen 34 via the intermediate molded body 42. Then, the first peripheral portion 16a of the intermediate formed body 42 is sandwiched and held by the platen 34 and the second upper die 36. As described above, the first peripheral portion 16a of the intermediate molded body 42 is formed to be higher in Hd than the first peripheral portion 16a of the target molded body 12 (see fig. 4). Therefore, even if the first peripheral portion 16a is held by the platen 34 and the second upper die 36, the inner region 44a and the outer region 44b of the intermediate formed body 42 do not contact the second upper die 36. Therefore, when the intermediate molded body 42 is held by the platen 34, the intermediate molded body 42 can be prevented from moving in contact with the second upper die 36 and damaging the appearance surface.

After that, as shown in fig. 7, the second upper die 36 is further lowered. Then, the inner region 44a comes into contact with the ridge portion 32a of the second lower die 32 and is gradually deformed into the shape of the ridge portion 14 of the target molded body 12. In addition, the outer region 44b is gradually deformed along the second lower die 32. Since the inner region 44a of the intermediate molded body 42 is bent inward of the ridge line portion 14, the length thereof is insufficient to form the ridge line portion 14 of the target molded body 12. The shortage is compensated for by the intermediate molded body 42 moving from the outer region 44b to the inner region 44 a. Further, since the portion of the intermediate molded body 42 other than the intermediate region 44 is kept in a state of floating between the second lower die 32 and the second upper die 36, the intermediate region 44 is molded preferentially over the other portions. This prevents excessive elongation from occurring in the vicinity of the ridge portion 14. When the intermediate molded body 42 is deformed, a gap is formed between the outer surface of the intermediate molded body 42 and the second upper die 36, and the gap is maintained until the second upper die 36 reaches the bottom dead center.

When the second upper die 36 is further lowered, as shown in fig. 8, the entire area of the intermediate molded body 42 is sandwiched between the second lower die 32 and the second upper die 36, and the small curvature portion of the ridge line portion 14 is molded. In the present embodiment, at the stage where the inner region 44a and the outer region 44b are extended to the maximum extent, the entire regions of the second lower die 32 and the second upper die 36 are closed, and therefore, when the ridge portion 14 having a small radius of curvature is molded, the extension of the intermediate molded body 42 is suppressed. As a result, the target molded body 12 can be formed while suppressing the occurrence of cracks in the vicinity of the ridge line portion 14. Since the length L1 of the cross section of the target molded body 12 along the intermediate region 44 is slightly longer than the length L0 of the cross section of the intermediate molded body 42 along the intermediate region 44, the intermediate region 44 of the intermediate molded body 42 is molded while being elongated at a predetermined elongation.

The press forming method of the present embodiment achieves the following effects.

The press-molding method of the present embodiment is a method of molding a plate material 10 into a target molded body 12 including a ridge line portion 14, and may include: a first step of molding an intermediate molded body 42 having an intermediate ridge line portion 44c, wherein the radius of the intermediate ridge line portion 44c is larger than the corner radius of the ridge line portion 14; and a second step of forming the target molded body 12 from the intermediate molded body 42, wherein the target molded body 12 and the intermediate molded body 42 have matching regions 46a, 46b and an intermediate region 44, the matching regions 46a, 46b are located on both sides of the intermediate ridge line portion 44c, and the cross-sectional shapes of the target molded body 12 and the intermediate molded body 42 are matched in the matching regions 46a, 46 b; in the intermediate region 44, the cross-sectional shapes of the target molded body 12 and the intermediate molded body 42 are not uniform, the intermediate region 44 has an outer region 44b and an inner region 44a, and the intermediate molded body 42 protrudes outside the target molded body 12 in the corner radius in the outer region 44 b; in the inner region 44a, the intermediate molded body 42 is bent inward of the corner radius than the target molded body 12. When the target molded body 12 is formed using such an intermediate molded body 42, the intermediate molded body 42 having a small radius of curvature can be insufficiently supplied from the outer region 44b to the ridge line portion 14 when the ridge line portion 14 having a small radius of curvature is formed. This enables the ridge portion 14 having a small radius of curvature to be molded without causing damage or cracking.

In the above-described press forming method, in the second step, the intermediate formed body 42 of the outer region 44b is moved toward the ridge line portion 14, thereby compensating for the shortage of the length when the inner region 44a is formed into the ridge line portion 14. This enables the ridge line portion 14 to be formed without excessive elongation. As a result, it is possible to prevent damage and cracking from occurring in the ridge portion 14, and it is possible to form a press-molded article having a clear ridge portion 14 with a small radius of curvature without causing surface distortion.

In the above press molding method, the length of the intermediate molded body 42 in the cross-sectional direction in the outer region 44b is longer than the length of the intermediate molded body 42 in the cross-sectional direction in the inner region 44 a. Accordingly, a sufficient amount of the intermediate molded body 42 can be supplied from the outer region 44b to the ridge portion 14.

In the above press molding method, the intermediate region 44 of the intermediate molded body 42 is formed of a plurality of arc regions having different curvatures, and has a reference inflection point 48b as a boundary of the arc region in the vicinity of a position to be the ridge line portion 14 of the target molded body 12, and the length L of the intermediate region 44 on the outer region 44b side of the reference inflection point 48b is larger than the length I of the intermediate region 44 on the opposite side of the outer region 44b from the reference inflection point 48 b. Accordingly, the amount of material can be controlled in the outer region 44b closer to the peripheral portion 16 than the ridge portion 32a that is likely to be elongated, so that elongation of the target molded body 12 at the ridge portion 14 can be suppressed, cracking of the ridge portion 14 can be prevented, and surface distortion of the outer region 44b can be prevented.

In the press molding method, the intermediate region 44 of the intermediate molded body 42 may include: a first arc region that curves from one end of the intermediate region 44 toward the inside of the target molded body 12; and a second arc region that is connected to the first arc region at the reference inflection point 48b and curved so as to protrude outward of the target molded body 12, the second arc region having a radius of curvature Rb that is larger than the radius of curvature Ra of the first arc region.

In the above-described press forming method, the maximum deviation Ha, which is the maximum deviation between the intermediate formed body 42 and the target formed body 12 in the press stroke direction in the inner region 44a, is larger than the maximum deviation Hb, which is the maximum deviation between the intermediate formed body 42 and the target formed body 12 in the press stroke direction in the outer region 44 b. Accordingly, in the second step, the second upper die 36 does not contact the upper surface of the intermediate molded body 42, and the intermediate molded body 42 does not contact the second lower die 32 during the clamping, so that the occurrence of damage due to sliding of the second lower die 32 and the second upper die 36 in contact with the intermediate molded body 42 can be suppressed, and the target molded body 12 without damage can be formed.

In the press molding method described above, the first step and the second step are performed in the molding dies 20 and 30, the molding dies 20 and 30 have the pressing plates 24 and 34 that hold the peripheral portion 16 of the plate material 10 before the ridge line portion 14 is pressed, and the outer region 44b of the intermediate molded body 42 is formed in a portion closer to the pressing plate 34 than the ridge line portion 14. This can control the extension of the pressure plate 34 side where the tensile force is generated, and can prevent the surface distortion in the vicinity outside the ridge line portion 14.

In the press forming method described above, the first step and the second step are performed in the forming dies 20 and 30, the forming dies 20 and 30 have the pressing plates 24 and 34 that hold the peripheral portion 16 of the plate material 10 before the ridge line portion 14 is pressed, and the height of the pressing plate 34 in the second step is set to be higher than the height of the pressing plate 24 in the first step by at least the maximum deviation Hb between the intermediate formed body 42 and the target formed body 12 in the outer region 44b in the press stroke direction. Accordingly, in the second step, the second upper die 36 does not contact the upper surface of the intermediate molded body 42, and the intermediate molded body 42 does not contact the second lower die 32 during the clamping, so that the occurrence of damage due to sliding of the second lower die 32 and the second upper die 36 in contact with the intermediate molded body 42 can be suppressed, and the target molded body 12 can be formed without damage.

In the press forming method, the length L of the peripheral portion (the second peripheral portion 16b) in the second step may be set to be equal to or less than the length L of the peripheral portion in the second step_2ndIs set to be longer than the length L of the peripheral portion (second peripheral portion 16b) of the first step_1stLong.

In the press-forming method, the outer peripheral portion of the plate material 10 may be formed into a quadrangle constituted by a first side 10a, a second side 10b, a third side 10c, and a fourth side 10d, wherein the second side 10b faces the first side 10 a; the third side 10c extends in a direction intersecting the first side 10 a; the fourth side 10d faces the third side 10c, and the ridge portion 14 is formed to extend from the first side 10a toward the second side 10b in the vicinity of the third side 10c and in the vicinity of the fourth side 10d, respectively. According to such a molding method, the clear ridge line portion 14 can be formed on a member such as an automobile hood.

In the above press molding method, the inner region 44a of the intermediate molded body 42 may be formed inside the ridge line portion 14 of the target molded body 12, and the outer region 44b of the intermediate molded body 42 may be formed outside the ridge line portion 14 of the target molded body 12.

In the above description, the present invention has been described with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and it goes without saying that various modifications can be made within the scope not departing from the gist of the present invention.