CN117840337A

CN117840337A - Press forming method

Info

Publication number: CN117840337A
Application number: CN202211209960.XA
Authority: CN
Inventors: 松谷健司
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2022-09-30
Filing date: 2022-09-30
Publication date: 2024-04-09
Also published as: JP2024052586A; US20240109114A1

Abstract

The invention discloses a stamping forming method. The press molding method comprises a molding step in which an intermediate molded body (30) having an intermediate ridge portion (32) with a large edge radius is pressed to form a target molded body (20), an upper die (48) has an upper die step portion (60) at a boundary portion between a product portion (22) and a discard portion (24), and the discard portion (24) of the intermediate molded body (30) has a separation portion (56), a 1 st contact portion (54), and a 2 nd contact portion (58), wherein the separation portion (56) is separated from the upper die (48) at an initial stage of the molding step to provide a stretching margin to the discard portion (24); the 1 st contact portion (54) and the 2 nd contact portion (58) are brought into contact with an upper die (48) at an initial stage of a molding process to prevent wrinkles from occurring. Accordingly, both prevention of local expansion of the reject portion and prevention of occurrence of wrinkles can be achieved.

Description

Press forming method

Technical Field

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

Background

Outer panels (outer panels) typified by a hood (bonnet), a side panel (side panel), and a door panel (door panel) of an automobile are generally produced by press molding (press molding) a metal plate. The outer panel is a part that determines the appearance of the automobile, and sometimes adopts a design having a ridge line portion with a small radius of curvature called a characteristic line. The press molding of such a ridge portion with a small radius of curvature requires advanced techniques. For example, international publication No. 2020/195591 discloses a press molding method of forming a ridge line portion of a small radius of curvature by press molding.

The press molding method described in international publication No. 2020/195591 forms an intermediate molded body having an intermediate ridge portion with a larger radius of curvature than the ridge portion by a first press step, and thereafter forms the intermediate ridge portion into a ridge portion with a smaller radius of curvature by a second press step. In this press molding method, a slack portion (outer region) is provided in the intermediate molded body in advance so as to deviate from the target molded body (target molded body 20) in the vicinity of the intermediate ridge portion. The slack portion is a margin of extension (elongation) of the plate material when forming the ridge line portion with a small radius of curvature, and can form the ridge line portion with a small radius of curvature by two pressing steps while preventing occurrence of cracks in the vicinity of the ridge line portion.

Disclosure of Invention

However, in the press molding method described above, when the angle (hereinafter referred to as the included angle θ.) of a pair of flat portions sandwiching the ridge line portion becomes small, the stretching of the ridge line portion increases, and therefore, a larger stretching margin is required. In the press molding method described above, if the slack portion is increased in order to secure the expansion margin of the ridge line portion, the intermediate molded body interferes with the upper die when the intermediate molded body is sandwiched by the upper die and a platen (blank holder). As a result, the conventional press molding method has a problem that the molded product is damaged when the included angle θ is reduced.

In order to prevent the intermediate mold body and the upper mold from interfering with each other and from being damaged, it is considered to increase the height of the step portion of the boundary between the product portion and the discard portion of the upper mold. In the case of using such an upper die, the intermediate formed body having the slack portion that expands more in the press stroke direction can be prevented from interfering with the upper die.

However, when the height of the step portion of the boundary between the product portion and the discard portion of the upper die is increased, the expansion of the discard portion is increased, and the boundary between the product portion and the discard portion is locally expanded. In order to prevent such partial stretching, a slack portion may be provided as a stretching margin in the reject portion, but it has been found that when the slack portion is provided in the reject portion, wrinkles may occur in the vicinity of the boundary between the product portion and the reject portion.

The present invention aims to solve the above-mentioned technical problems.

The following aspect of the invention provides a press molding method for forming a plate material into a target molded body, wherein the plate material has a product portion and a discard portion, the discard portion being located on an outer periphery of the product portion and being cut out from the product portion after molding, the target molded body is a molded body including a ridge line portion in the product portion, the press molding method having a 1 st step and a 2 nd step, and in the 1 st step, an intermediate molded body having an intermediate ridge line portion with an edge radius larger than an edge radius of the ridge line portion is formed; in the step 2, the target molded body is formed from the intermediate molded body, and the product portion of the intermediate molded body has an inner portion and a slack portion, wherein the inner portion is offset inward in the edge radial direction from the target molded body; the relaxation section is offset to the outside in the edge radial direction from the target molded body, and the discard section of the intermediate molded body has a separation section and a contact section, wherein the separation section is separated from the upper die of the 2 nd step at the initial stage of the 2 nd step to provide a stretching margin for the discard section; the contact portion is in contact with the upper die in the 2 nd step, and prevents the plate from moving at the initial stage of the 2 nd step.

In the press molding method of the above aspect, the intermediate mold body of the discard portion has a separation portion separated from the upper mold, so that the extension margin of the discard portion can be ensured. In the press molding method, the discard portion is in contact with the upper die, so that it is possible to prevent the excessive material from being supplied at the initial stage of the molding process, thereby preventing the occurrence of wrinkles. Therefore, the press molding method of the above embodiment can simultaneously prevent the local extension of the reject portion and the generation of wrinkles.

The above objects, features and advantages should be easily understood by the following description of the embodiments with reference to the attached drawings.

Drawings

Fig. 1 is a perspective view of a target molded article according to an embodiment.

Fig. 2 is a cross-sectional view of the intermediate molded body according to the embodiment and the molding die used in step 2, and shows a cross-section corresponding to the position of line II-II in fig. 1.

Fig. 3 is an enlarged cross-sectional view of the vicinity of the reject portion in the hold step of step 2 of the embodiment.

Fig. 4A is a cross-sectional view of a step of disposing the intermediate molded body in the molding die of step 2, and fig. 4B is an enlarged cross-sectional view of the vicinity of the discard portion of fig. 4A.

Fig. 5 is a cross-sectional view of the holding step.

Fig. 6A is a cross-sectional view of a step (initial stage) of pressing the intermediate formed body between the upper die and the lower die, and fig. 6B is an enlarged cross-sectional view of the vicinity of the discard portion of fig. 6A.

Fig. 7A is a cross-sectional view of a step (end stage) of pressing the intermediate formed body between the upper die and the lower die, and fig. 7B is an enlarged cross-sectional view of the vicinity of the discard portion of fig. 7A.

Fig. 8 is a cross-sectional view showing an initial deformation of a molding step when the intermediate molded body is press molded by the press molding method according to the comparative example.

Detailed Description

The press molding method of the present embodiment is suitable for manufacturing, for example, the roof panel and the trunk portion outer panel 10 of an automobile. This press molding method is suitable for molding an outer panel 10, and the outer panel 10 has, for example, a ridge line portion 16 sandwiched by flat portions 14 of 90 ° or less of a spoiler (spoler) 12 or the like. This embodiment describes an example of forming the rectangular plate 18 shown in fig. 1. The illustrated plate material 18 is a target molded body 20 after press molding, and has the shape of the outer plate 10 of the trunk portion. In fig. 1, the plate 18 is shown in a state of being cut at the center in the width direction.

The target molded body 20 has the ridge portion 16 in the product portion 22. The ridge portion 16 has a curvature radius (edge radius) as small as 2.5mm to 9mm, for example, and has a sharp-blade-like appearance. The ridge portion 16 is, for example, a portion of the spoiler 12, and is integrally formed with the outer panel 10. The target molded body 20 has a 1 st slope 14a on one side of the ridge portion 16 and a 2 nd slope 14b on the other side of the ridge portion 16. The ridge portion 16 is sandwiched between the 1 st slope 14a and the 2 nd slope 14b. The angle between the 1 st slope 14a and the 2 nd slope 14b is referred to as the angle θ. The press molding method of the present embodiment can mold the target molded body 20 having a small included angle θ, for example, 30 ° to 90 °.

The plate 18 used in the press molding method of the present embodiment is made of, for example, a thin metal plate such as steel or an aluminum alloy having a thickness of 0.3 to 3 mm. Sheet 18 has a product portion 22 and a reject portion 24. The product portion 22 is located on the center side of the plate 18 and is a portion formed into the shape of a product. The reject portion 24 is located at the peripheral portion of the sheet material 18, and is a band-like portion surrounding the product portion 22.

The reject portion 24 is located at a peripheral portion of the sheet material 18, surrounding the outside of the product portion 22. As shown in fig. 2, the reject portion 24 has a 1 st region 26 held by the platen 44 when the intermediate formed body 30 is press-formed, and a 2 nd region 28 facing the upper die step 60 of the upper die 48. The discard portion 24 is cut out from the product portion 22 after the press molding method of the present embodiment is completed.

The press molding method of the present embodiment includes a 1 st step and a 2 nd step. Step 1 is a step of forming an intermediate-molded body 30 shown in fig. 2 from a flat plate-like plate 18. The 1 st step may be press molding (drawing molding) or may be a method other than press molding.

Next, the intermediate molded body 30 will be described. The intermediate molded body 30 has an intermediate ridge portion 32, a step portion 36, and a fixing structure 38. Wherein the intermediate ridge portion 32 is located in the product portion 22 and has an inner portion 33 and a slack portion 34. On the other hand, the stepped portion 36 and the fixing structure 38 are located at the discarding portion 24.

The intermediate ridge portion 32 is a ridge-shaped portion provided at a portion forming the ridge portion 16 of the target molded body 20, and has an edge radius larger than the edge radius of the ridge portion 16. The inner portion 33 of the intermediate ridge portion 32 is offset downward from the shape of the target molded body 20. The slack portion 34 is located on the side of the inner portion 33 (on the side of the 2 nd incline surface 14 b), and is connected to the inner portion 33 by a smooth edge radius. The slack portion 34 is offset to bulge outward (upward) of the edge radius with respect to the 2 nd slope 14b of the target molded body 20. The product portion 22 of the intermediate molded body 30 other than the intermediate ridge portion 32 is a conforming portion 35 conforming to the shape of the target molded body 20. The conforming portion 35 appears on both side portions of the intermediate ridge portion 32.

As shown in fig. 3 in enlarged form, the stepped portion 36 is located at the reject portion 24. The stepped portion 36 is inclined downward at a steep angle with respect to the 1 st inclined surface 14a and the 2 nd inclined surface 14b of the product portion 22. A part of the stepped portion 36 is sandwiched between the upper die 48 and the lower die 64 and molded. The fixing structure 38 is provided adjacent to the outer peripheral side of the stepped portion 36. The fixing structure 38 is connected to the stepped portion 36 through a bent portion 38 a. The inclination of the fixing structure 38 of the present embodiment is smaller than that of the stepped portion 36.

The fixed structure 38 has locking ribs 40 and adjusting ribs 42. The locking rib 40 and the adjusting rib 42 extend in a groove shape along the outer circumference of the plate 18. Wherein the adjusting rib 42 is located on the inner peripheral side and the locking rib 40 is located on the outer peripheral side. The locking rib 40 is held by the locking recess 46 of the pressing plate 44 and the locking protrusion 50 of the upper die 48 to prevent positional displacement of the plate 18. The locking rib 40 is deformed into a rectangular concave shape by the pressing plate 44 and the upper die 48 in the holding process.

The adjustment lug 42 is located between the locking lug 40 and the step 36. In order to form a portion separated from the upper die 48, the adjusting rib 42 has a semicircular shape in cross-section with a concave upper side. The adjustment rib 42 is accommodated in the adjustment recess 52 of the platen 44. The adjusting rib 42 appears in the intermediate molded body 30 and disappears in the target molded body 20. The adjustment rib 42 serves as a margin for the discard portion 24 in step 2. At the end of step 2, the adjusting rib 42 is stretched to deform into the shape of the target molded body 20 along the upper die 48.

The inner peripheral end (inner end) of the adjusting rib 42 is a 1 st contact portion 54 that is in line contact with the platen 44 and the upper die 48 in the holding step of fig. 3. The portion on the inner peripheral side of the 1 st contact portion 54 is a separation portion 56 that separates the intermediate molded body 30 from the upper die 48 in the holding step. The separation portion 56 extends to a 2 nd contact portion 58 midway in the step portion 36. The separation portion 56 is a portion of the intermediate molded body 30 that is relaxed from the upper die 48, and is the expansion margin in step 2.

As shown in the figure, the 2 nd contact portion 58 is a portion that makes line contact with the upper die step portion 60 of the upper die 48 in the holding step. The 1 st contact portion 54 and the 2 nd contact portion 58 prevent the movement of the discard portion 24 by friction force at an initial stage from the holding process to the molding process. Accordingly, the 1 st contact portion 54 and the 2 nd contact portion 58 prevent the excessive supply of the expansion margin, thereby preventing the generation of wrinkles.

The 2 nd step is a step performed after the 1 st step, and is a step of press-molding the intermediate molded body 30 into the target molded body 20. As shown in fig. 2, step 2 is performed using a molding die 62. The molding die 62 has a platen 44, an upper die 48, and a lower die 64. Next, the molding die 62 will be described.

The platen 44 supports the securing structure 38 of the reject portion 24 of the sheet material 18 from below. Platen 44 extends annularly along the outer periphery of sheet 18. The pressing plate 44 has a locking recess 46 and an adjustment recess 52 on the upper surface 44 a. The locking recess 46 is a concave groove that accommodates the locking bead 40 of the intermediate mold body 30. The locking recess 46 is arranged at a position corresponding to the locking rib 40, and extends annularly in a plan view. The locking concave portion 46 is fitted with the locking convex portion 50 of the upper die 48 after the holding process. The locking concave portion 46 sandwiches the locking rib 40 holding the intermediate formed body 30 between it and the locking convex portion 50.

The adjustment concave portion 52 is a concave groove that accommodates the adjustment rib 42 of the intermediate molded body 30. The adjustment recess 52 is located on the inner peripheral side of the lock recess 46. The adjustment concave portion 52 is arranged at a position corresponding to the adjustment rib 42, and extends annularly in a plan view. The cross section of the adjustment concave part 52 is a semicircle, and the adjustment concave part 52 has the same shape as the semicircular adjustment convex rib 42 of the intermediate molded body 30. As shown in fig. 3, in the holding step, the adjustment concave portion 52 accommodates the adjustment rib 42.

The pressing plate 44 can be lifted up and down, and in the holding step of step 2, the intermediate molded body 30 is sandwiched between the upper die 48 and the upper die 48 as the upper die 48 is lowered. The platen 44 descends together with the upper die 48 when pressed downward by the upper die 48. In the holding step, the 1 st contact portion 54 at the inner end of the adjustment rib 42 is pressed against the upper die 48 by the edge of the adjustment recess 52 of the platen 44. The pressing plate 44 has a guide 53 on the inner peripheral side of the adjustment recess 52. The guide portion 53 has an inclination that guides the adjustment rib 42 to the adjustment recess 52. The guide 53 is separated from the upper die 48 in the holding step. In step 2, the guide portion 53 forms a gap in which the expansion margin of the discard portion 24 can be displaced.

As shown in fig. 2, the lower die 64 is located inside the platen 44 and is surrounded by the platen 44. The lower die 64 is disposed below the upper die 48 so as to face the upper die 48. The lower die 64 has a molding surface 66 at an upper portion. The molding surface 66 of the lower die 64 conforms to the shape of the target molded body 20. The molding surface 66 of the lower mold 64 presses the 2 nd region 28 of the intermediate molded body 30 in the molding step, and molds the intermediate molded body 30 into the target molded body 20. As shown in fig. 3, the lower die 64 has a lower die step portion 70 at a peripheral edge portion 68 on the outer peripheral side. The lower die step 70 is a portion that abuts against the discard portion 24 of the plate 18, and abuts against the step 36 of the intermediate formed body 30. The lower die step 70 is inclined at a steep angle to the lower side of the 1 st inclined surface 14a and the 2 nd inclined surface 14b.

As shown in fig. 2, the upper die 48 is disposed above the platen 44 and the lower die 64. The upper die 48 has a molding surface 72 (lower surface) facing the upper surface 44a of the platen 44 and the molding surface 66 of the lower die 64. The molding surface 72 has the same shape as the target molded body 20. The molding surface 72 has an upper die step 60 at an outer peripheral portion. The upper die step 60 is a portion that abuts against the step 36 of the intermediate molded body 30, and has the same shape as the lower die step 70. The height of the upper die step 60 in the stroke direction is larger than the height of the step 36 of the intermediate molded body 30 in the stroke direction. Such an upper die step 60 can hold the intermediate formed body 30 at a position farther from the forming surface 72 of the upper die 48. Therefore, the upper die 48 of the present embodiment can prevent contact with the slack portion 34 of the intermediate formed body 30 in the holding step.

The upper die 48 has a clamping portion 74 on the outer peripheral side of the upper die step portion 60 for clamping the plate 18 between it and the platen 44. The clip portion 74 has the locking protrusion 50. The locking convex portion 50 is located at a position corresponding to the locking concave portion 46 of the pressing plate 44, and has a convex shape to be fitted into the locking concave portion 46. The locking protrusion 50 sandwiches the locking rib 40 of the intermediate formed body 30 between it and the locking recess 46. The locking protrusions 50 and locking recesses 46 prevent the intermediate formed body 30 from being displaced relative to the upper die 48. Further, a portion of the upper die 48 located above the adjustment recess 52 of the platen 44 is formed in a flat shape.

Next, a specific process of the 2 nd process of the press molding method according to the present embodiment will be described.

First, as shown in fig. 4A and 4B, the intermediate-formed body 30 is disposed above the platen 44 and the lower die 64. The pressing plate 44 is stopped at the upper end position in the initial state. The platen 44 protrudes above the lower die 64 by a predetermined height in the press stroke direction in the initial state. The intermediate-formed body 30 is disposed such that the reject portion 24 overlaps the platen 44, and such that the product portion 22 overlaps the lower die 64. The intermediate ridge portion 32 of the intermediate molded body 30 is overlapped on the ridge portion 16a of the lower die 64 and the vicinity thereof. As shown in fig. 4B, the locking rib 40 of the intermediate-formed body 30 is fitted into the locking recess 46 of the pressing plate 44, and the adjusting rib 42 of the intermediate-formed body 30 is fitted into the adjusting recess 52 of the pressing plate 44.

Next, as shown in fig. 5, when the upper die 48 is lowered, the upper die 48 presses the fixing structure 38 of the intermediate molded body 30 against the pressing plate 44 (holding step). As a result, as shown in fig. 3, the intermediate-formed body 30 is sandwiched between the platen 44 and the upper die 48. The locking rib 40 is sandwiched between the locking protrusion 50 of the upper die 48 and the locking recess 46 of the lower die 64 and is sandwiched between the upper die 48 and the platen 44. The locking bead 40 is plastically deformed into the shape of the locking boss 50 and the locking recess 46. The intermediate molded body 30 on the center side of the adjusting rib 42 is in contact with the upper die 48 only at the 1 st contact portion 54 on the inner side of the adjusting rib 42 and the 2 nd contact portion 58 of the step portion 36. The portions of the intermediate formed body 30 other than the 1 st contact portion 54 and the 2 nd contact portion 58 are separated from the forming surface 72 of the upper die 48. The distance H between the conforming portion 35 of the intermediate molded body 30 and the upper die 48 in the traveling direction _2nd 。

As shown in fig. 2, when the intermediate molded body 30 and the target molded body 20 (the molding surface 66 of the lower die 64 in fig. 2) are overlapped, the slack portion 34 has a relaxed shape that bulges upward with respect to the shape of the target molded body 20. The slack portion 34 serves as a margin for stretching the inner portion 33 when the intermediate molded body 30 is molded into the target molded body 20, thereby suppressing the tension of the ridge line portion 16 and preventing the ridge line portion 16 from cracking.

As the angle θ between the 1 st slope 14a and the 2 nd slope 14b adjacent to the ridge line portion 16 becomes smaller, the expansion margin when molding the ridge line portion 16 increases. The smaller the angle θ, the more the bulge of the slack 34 needs to be increased. However, when the bulge of the slack portion 34 is large, if the intermediate-formed body 30 is held by the platen 44 to the upper die 48, the slack portion 34 interferes with the upper die 48, and the intermediate-formed body 30 is damaged or dented.

Therefore, in the present embodiment, as described above, the upper die 48 having the upper die step 60 larger than the height of the step 36 of the intermediate formed body 30 is used. Such an upper die 48 can increase the distance H between the conforming portion 35 of the intermediate formed body 30 and the upper die 48 _2nd . Therefore, in the press molding method of the present embodiment, the intermediate molded body 30 having the larger bulged slack portion 34 can be fixed to the upper die 48 without interfering with the upper die 48.

When the height of the step 36 of the intermediate molded body 30 is smaller than the height of the upper mold step 60, the difference in length of the discard portion 24 between the intermediate molded body 30 and the target molded body 20 increases.

As described with reference to fig. 3, in the press molding method of the present embodiment, the reject portion 24 of the intermediate molded body 30 has the separating portion 56 and the adjusting rib 42. These portions are relaxed with respect to the target molded body 20. Therefore, when the separating portion 56 and the adjusting rib 42 disappear in the molding process, the expansion margin of the discarding portion 24 can be provided.

Next, in step 2, as shown in fig. 6A, the upper die 48 is lowered to enter the molding step. The intermediate molded body 30 descends together with the upper die 48. The platen 44 is held in a state of sandwiching the intermediate formed body 30 between the intermediate formed body and the upper die 48 while being pressed downward by the upper die 48. The clearance between the lower die 64 and the upper die 48 in the traveling direction is smaller than the distance H _2nd When the intermediate formed body 30 is sandwiched between the upper die 48 and the lower die 64, deformation starts. The inner portion 33 and the slack portion 34 of the intermediate ridge portion 32 are gradually deformed.

At the initial stage of the molding process, the separating portion 56 and the adjusting rib 42 are deformed also at the reject portion 24 of the intermediate molded body 30. As a result, at the reject portion 24, the sheet material 18 moves in the direction of the molding surface 66. At this time, the 1 st contact portion 54 and the 2 nd contact portion 58 prevent the discard portion 24 from wrinkling.

The press molding method of the comparative example shown in fig. 8 shows an example in which the 1 st contact portion 54 and the 2 nd contact portion 58 are not provided in the reject portion 24 of the intermediate molded body 30A. In this comparative example, at the initial stage of the molding process, the sheet 18 moves from the 1 st region 26 to the product portion 22. In the comparative example, since the movement of the plate material 18 is not prevented by the 1 st contact portion 54 and the 2 nd contact portion 58, excessive feeding of the plate material to the center side occurs. As a result, as shown by the two-dot chain line in fig. 8, the sheet material 18 is deformed in a loose manner, and the reject portion 24 is wrinkled 31.

In contrast, in the press molding method of the present embodiment, as shown in fig. 6B, the movement of the plate 18 of the reject portion 24 of the intermediate formed body 30 is suppressed by the 1 st contact portion 54 and the 2 nd contact portion 58. The 1 st contact portion 54 and the 2 nd contact portion 58 suppress the movement of the discard portion 24 of the intermediate formed body 30 by friction with the upper die 48, thereby preventing the excessive supply of the plate material 18 and preventing the generation of wrinkles.

Next, as shown in fig. 7A, the molding process is continued, and the intermediate molded body 30 is pressed by the upper die 48 and the lower die 64. As a result, the intermediate molded body 30 is molded into the target molded body 20. The stretching of sheet material 18 when inner portion 33 is formed into ridge portion 16 is compensated by movement of sheet material 18 of slack portion 34 shown in fig. 2 toward ridge portion 16. Therefore, the press molding method of the present embodiment can prevent cracking of the ridge line portion 16.

As shown in fig. 7B, in the discard portion 24, the target molded body 20 is sandwiched between the upper die step portion 60 and the lower die step portion 70, and is molded into the shape of the discard portion 24. When the separating portion 56 and the adjusting rib 42 stretch and disappear, the stretch of the discarding portion 24 can be compensated. Therefore, the press molding method of the present embodiment can prevent the reject portion 24 from generating excessive tension.

Through the above steps, the sheet material 18 is molded into the target molded body 20, and the press molding method of the present embodiment ends. As described above, according to the press molding method of the present embodiment, the target molded body 20 having the ridge line portion 16 having the small angle θ can be efficiently produced in the two-stage molding process. Further, since the slack portion 34 of the intermediate molded body 30 and the upper die 48 can be prevented from interfering with each other, the product portion 22 can be prevented from being damaged, and a molded article having a good appearance can be produced. Further, the press molding method can prevent the occurrence of local stretching or wrinkling of the reject portion 24, and thereby can prevent degradation of the quality of the product portion 22 due to the reject portion 24.

The above inventions are summarized as follows.

One embodiment provides a press molding method for forming a plate 18 into a target molded body 20, wherein the plate 18 has a product portion 22 and a discard portion 24, the discard portion 24 being located on an outer periphery of the product portion and being cut out from the product portion after molding, the target molded body 20 is a molded body including a ridge line portion 16 in the product portion, the press molding method having a 1 st step and a 2 nd step, and in the 1 st step, an intermediate molded body 30 having an intermediate ridge line portion 32 with an edge radius larger than an edge radius of the ridge line portion is formed; in the step 2, the target molded body is formed from the intermediate molded body, and the product portion of the intermediate molded body has an inner portion 33 and a slack portion 34, wherein the inner portion 33 is offset inward in the edge radial direction from the target molded body; the relaxation section 34 is offset to the outside in the edge radial direction from the target molded body, and the reject section of the intermediate molded body has a separation section 56 and contact sections 54, 58, wherein the separation section 56 is separated from the upper die 48 of the 2 nd step at the initial stage of the 2 nd step to provide a stretching margin for the reject section; the contact portions 54, 58 contact the upper die in the 2 nd step, and prevent the plate from moving at the initial stage of the 2 nd step.

In the press molding method, the intermediate molded body of the discard portion has a separation portion separated from the upper die, so that the extension margin of the discard portion can be ensured. In the press molding method, the discard portion is in contact with the upper die, so that excessive supply of material at the initial stage of the molding process can be prevented, and generation of wrinkles can be prevented. Therefore, the press molding method of the above embodiment can simultaneously prevent the local extension of the reject portion and the generation of wrinkles.

In the press molding method, the molding die 62 of the step 2 may have the upper die 48, the lower die 64, and the platen 44, wherein the upper die 48 may have the shape of the target molded body; the lower die 64 is opposite to the upper die; the platen 44 is disposed on the outer peripheral side of the lower die, and the reject portion of the intermediate molded body is sandwiched between the platen and the upper die, and the 2 nd step has a holding step of sandwiching the reject portion by the platen and the upper die, and a molding step; in the molding step, the intermediate molded body is pressed by the upper die and the lower die to mold the target molded body, the upper die has an upper die step 60 at a boundary portion between the product portion and the discard portion, and the separation portion of the intermediate molded body is disposed at a position facing the upper die step. In this press molding method, the expansion margin is provided in the reject portion, and the occurrence of wrinkles due to the sheet material moving inward (excessive feeding) can be prevented.

In the press molding method, the intermediate molded body may have an adjustment rib 42 at a position sandwiched between the platen and the upper die, and the adjustment rib 42 may be separated from the upper die to provide a stretching margin. In this press molding method, the intermediate molded body further has an adjustment rib as a margin for expansion of the discard portion, whereby excessive tension due to local expansion of the discard portion can be relaxed.

In the press molding method, the press plate may have an adjustment concave portion 52, and the adjustment concave portion 52 may receive the adjustment rib to separate the intermediate molded body from the upper die. In this press molding method, a large expansion margin can be provided in a narrow space by providing the expansion margin at a portion in contact with the platen.

In the press molding method, the contact portion may have a 1 st contact portion 54 and a 2 nd contact portion 58, wherein the 1 st contact portion 54 is in line contact with the upper die at an inner end portion of the adjustment rib; the 2 nd contact portion 58 is in line contact with the upper die step portion, and the separation portion is located between the 1 st contact portion and the 2 nd contact portion. In this press molding method, the movement of the material in the initial stage of the molding step can be prevented by adjusting the 1 st contact portion between the rib and the upper die and the 2 nd contact portion between the step portion and the upper die. As a result, the press molding method can prevent wrinkles from occurring in the reject portion.

In the press molding method, in the molding step, the separation portion and the adjustment rib of the intermediate molded body may be extended to deform the discard portion into a shape that is in close contact with the upper die. In this press molding method, the separation portion and the adjustment rib are stretched to be closely attached to the upper die in the molding step, whereby the generation of excessive tension in the discard portion can be suppressed.

The present invention is not limited to the above-described invention, and various configurations can be adopted without departing from the scope of the present invention.

Claims

1. A press molding method for forming a plate material (18) into a target molded body (20), wherein the plate material (18) has a product portion (22) and a discard portion (24), the discard portion (24) being located on the outer periphery of the product portion (22) and being cut out from the product portion (22) after molding, the target molded body (20) is a molded body including a ridge line portion (16) in the product portion (22),

it is characterized in that the method comprises the steps of,

has a 1 st procedure and a 2 nd procedure,

in the step 1, an intermediate molded body (30) having an intermediate ridge portion (32) with an edge radius larger than that of the ridge portion (16) is formed;

in the step 2, the target molded body (20) is formed from the intermediate molded body (30),

the product portion (22) of the intermediate molded body (30) has an inner portion (33) and a slack portion (34), wherein the inner portion (33) is offset inward in the edge radial direction than the target molded body (20); the slack portion (34) is offset to the outside in the edge radial direction than the target molded body (20),

the discarding part (24) of the intermediate formed body (30) is provided with a separating part (56) and contact parts (54, 58), wherein the separating part (56) is separated from the upper die (48) of the 2 nd step at the initial stage of the 2 nd step to provide a stretching allowance for the discarding part (24); the contact portions (54, 58) are in contact with the upper die (48) in the 2 nd step, and prevent the sheet material (18) from moving at the initial stage of the 2 nd step.

2. The press molding method according to claim 1, wherein,

the molding die (62) of the 2 nd step has the upper die (48), a lower die (64) and a pressing plate (44), wherein the upper die (48) has the shape of the target molded body (20); the lower die (64) is opposite to the upper die (48); the platen (44) is disposed on the outer peripheral side of the lower die (64) and sandwiches the reject portion (24) of the intermediate formed body (30) between the lower die and the upper die (48),

the 2 nd step comprises a holding step and a molding step,

in the holding step, the reject unit (24) is held by the platen (44) and the upper die (48);

in the molding step, the intermediate molded body (30) is pressed by the upper die (48) and the lower die (64) to mold the target molded body (20),

the upper die (48) has an upper die step (60) at a boundary portion between the product portion (22) and the discard portion (24),

the separation portion (56) of the intermediate molded body (30) is disposed at a position facing the upper die step portion (60).

3. The press molding method according to claim 2, wherein,

the intermediate molded body (30) has an adjustment rib (42) at a position sandwiched between the platen (44) and the upper die (48), and the adjustment rib (42) is separated from the upper die (48) to provide a stretching margin.

4. The press molding method according to claim 3, wherein,

the platen (44) has an adjustment recess (52), and the adjustment recess (52) accommodates the adjustment rib (42) to separate the intermediate molded body (30) from the upper die (48).

5. The press forming method according to claim 3 or 4, wherein,

the contact parts (54, 58) are provided with a 1 st contact part (54) and a 2 nd contact part (58), wherein the 1 st contact part (54) is in line contact with the upper die (48) at the inner end part of the adjusting rib (42); the 2 nd contact portion (58) is in line contact with the upper die step portion (60), and the separation portion (56) is located between the 1 st contact portion (54) and the 2 nd contact portion (58).

6. The press molding method according to claim 5, wherein,

in the molding step, the separation portion (56) and the adjustment rib (42) of the intermediate molded body (30) are stretched to deform the discard portion (24) into a shape that is in close contact with the upper die (48).