JP2022139529A - Press device, and press molded product manufacturing method - Google Patents

Abstract

To provide a press device which can effectively suppress torsion and wall camber when manufacturing a press molded product that is long and has a hat-shaped cross section, and includes a part curving in a plan view.SOLUTION: A press device 1 comprises: a lower punch 4 including a top face with a curved part; a lower cushion 5 which supports the lower punch 4; an inside lower jig 6i; an upper pad 7; and an upper die 8. The inside lower jig 6i is so located as to be adjacent to an inside bottom surface 43i of the lower punch 4. The inside lower jig 6i has an inside lower blade 61i at an edge adjacent to the inside bottom surface 43i of the lower punch 4. The inside lower jig 6i has an inner groove 62i, which is formed along a curved inner side edge of the curved part, in a top face. The upper die 8 has an inside upper blade 84i at an edge adjacent to an inside recess 83i of an inside lower surface 82i. The upper die 8 has an inner convex ridge 85i projecting from the inside lower surface 82i at a position facing the inner groove 62i of the inside recess 83i.SELECTED DRAWING: Figure 6

Description

The present invention relates to a press machine and a method of manufacturing a press-formed product using the press machine.

Many of the parts that make up the vehicle body of an automobile are formed by press working using a mold. This type of press-formed product is manufactured by drawing or bending a blank made of a metal plate. In recent years, press-molded products for automobiles are required to be lighter and stronger. In order to meet this requirement, blanks having high strength (tensile strength) are used when producing press-formed products.

However, when a high-strength blank is used, springback tends to occur in the obtained press-molded product. For this reason, it is difficult to ensure the target dimensional accuracy unless some measures are taken during press molding.

In particular, when the press-formed product is long, has a hat-shaped cross section, and includes a curved portion in a plan view, the press-formed product may be twisted or warped in the vertical wall (hereinafter, also referred to as "wall warp"). ) is likely to occur. Examples of automobile press-molded products having such a shape include an A-pillar upper (front pillar upper), a roof rail, and a front side member front.

Generally, a press-formed product is manufactured through a plurality of steps. Therefore, if the press-formed product is significantly twisted and wall warped, the press-formed product cannot be set in the mold in the next step. In this case, even correction in the next process is difficult. Therefore, there is a demand for a technique for suppressing twisting and wall warping of press-formed products.

Conventional techniques for suppressing torsion and wall warpage include, for example, Japanese Patent Application Laid-Open No. 2008-213028 (Patent Document 1), Japanese Patent Application Laid-Open No. 2008-000778 (Patent Document 2), and Japanese Patent Application Laid-Open No. 2016-002583 (Patent Document 3).

Patent Literature 1 discloses a technique of forming embossments on the web surface of a channel material during press molding. In Patent Document 1, only by applying a relatively simple process of forming embossing on the web surface during press molding, when the molded product is removed from the mold after press working, the molded product may be twisted due to springback. It is described that it is very small and does not cause any inconvenience in assembling parts or the like.

Patent Document 2 discloses that when manufacturing a hat-shaped metal part having a U-shaped or V-shaped cross-sectional shape comprising a ceiling portion, a vertical wall portion, and a flange portion, at least one of the vertical wall portions is manufactured by press molding. Disclosed is a technique of forming a plurality of holes with a width of 10 mm or less in the part to relieve residual stress after press molding. Patent Literature 2 describes that a hat-shaped metal part having excellent shape fixability without twisting or deformation can be obtained.

Patent Document 3 manufactures a molded product 11 having a groove-shaped portion 13 extending in the longitudinal direction and having flange portions curved along the longitudinal direction on both of a pair of vertical wall portions 13b forming the groove-shaped portion 13. Disclose the technology to In the technique of Patent Document 3, a punch 3 for forming a groove-shaped portion 13, a flange forming die 5 movably provided on both sides of the punch 3, and a die 7 having a groove-shaped forming portion 7a and a flange forming portion 7b. and press molding using. At the time of press forming, when the distance from the bottom dead center of the die 7 during forming is H, and the distance from the top dead center of the flange forming die 5 during forming is D, H>0 during forming. D>0, and H=D=0 at the time of molding into a product shape. Patent Document 3 describes that three-dimensional springback such as twisting and bending can be reduced.

Japanese Patent Application Laid-Open No. 2008-213028 Japanese Patent Application Laid-Open No. 2008-000778 JP 2016-002583 A

In the techniques of Patent Document 1 and Patent Document 2, it is necessary to emboss or perforate the product. In this case, the product is likely to be deformed starting from the embossments and holes. This can reduce product stiffness, strength, and crash performance. In addition, in the technique of Patent Document 2, since the product is perforated, there is a concern that the rust prevention performance may be lowered. Therefore, the techniques of Patent Documents 1 and 2 are not practical.

The technique of Patent Document 3 requires a movable flanging die 5 during press forming. When a general press is used, a predetermined load is simply applied to the mold corresponding to the flange forming die 5 from the die of the press via a cushion pin or via a gas cushion. Therefore, it is difficult to perform complicated position control during molding, and the technique of Patent Document 3 is not practical.

Therefore, a technique for effectively suppressing twisting and wall warping is highly desired.

An object of the present invention is to provide a press apparatus that can effectively suppress torsion and wall warpage when manufacturing a press-formed product that is long and has a hat-shaped cross section and includes a curved portion in a plan view. and to provide a method for manufacturing a press-formed product.

A press apparatus according to one embodiment of the present invention comprises a bed, a slide, a lower punch, a lower cushion, an inner lower jig, an upper pad and an upper die. The slide can be raised and lowered with respect to the bed. The lower punch has an elongated top surface, an inner side surface, an outer side surface, an inner bottom surface, and an outer bottom surface. The top surface has an in-plane curvature. The inner side surface connects to the curved inner side edge of the curved portion of the side edges of the top surface. The outer side surface connects to the curved outer side edge of the curved portion of the side edges of the top surface. The inner bottom surface joins the lower edge of the inner side surface. The outer bottom surface joins the lower edge of the outer side surface. A lower cushion supports the lower punch and is fixed to the bed.

The inner lower jig is arranged adjacent to the inner bottom surface of the lower punch and fixed to the bed. The inner lower jig has an inner lower blade on the edge of the upper surface of the inner lower jig adjacent to the inner bottom surface of the lower punch. The inner lower jig has an inner groove formed on its upper surface along the curved inner side edge of the curved portion. The upper pad is arranged to face the top surface of the lower punch. The upper pad is supported by the slide via elastic members.

The upper die is fixed to the slide. The upper die has an inner wall surface, an outer wall surface, an inner lower surface, an outer lower surface, and an inner recess. The inner wall surface corresponds to the inner side surface of the lower punch. The outer wall surface corresponds to the outer side surface of the lower punch. The inner bottom surface faces the inner bottom surface of the lower punch. The outer lower surface faces the outer bottom surface of the lower punch. The inner recess is adjacent to the inner lower surface. The upper die has an inner upper blade on the edge of the inner lower surface adjacent to the inner recess. The upper die has an inner ridge projecting from the inner bottom surface at a position facing the inner groove on the bottom surface of the inner recess.

A method of manufacturing a press-formed product according to one embodiment of the present invention is a manufacturing method using the press apparatus of the above one embodiment. A press-formed product manufactured by the manufacturing method includes an elongated top plate, an inner vertical wall, an outer vertical wall, an inner flange, and an outer flange. The top plate has a curved portion that curves in-plane. The inner vertical wall connects to the curved inner side edge of the curved portion of the side edges of the top plate. The outer vertical wall connects to the curved outer side edge of the curved portion of the both side edges of the top plate. The inner flange joins the lower edge of the inner longitudinal wall. The outer flange joins the lower edge of the outer longitudinal wall.

The manufacturing method includes steps (a) to (e). In step (a), a blank made of a metal plate is prepared. The blank has a size exceeding the installation area of the inner ridge of the upper die. In step (b), the blank is placed on top of the lower punch. In step (c), the slide is lowered to clamp the blank between the upper pad and the top surface of the lower punch. In step (d), the slide is further lowered, and the blank is pressed by the upper die and the lower punch, as well as by the inner ridge and the inner groove. In step (e), the slide is further lowered to cut the blank with the inner upper and inner lower blades.

A press apparatus according to another embodiment of the present invention comprises a bed, a slide, a lower punch, a lower cushion, an outer lower jig, an upper pad and an upper die. The slide can be raised and lowered with respect to the bed. The lower punch has an elongated top surface, an inner side surface, an outer side surface, an inner bottom surface, and an outer bottom surface. The top surface has an in-plane curvature. The inner side surface connects to the curved inner side edge of the curved portion of the side edges of the top surface. The outer side surface connects to the curved outer side edge of the curved portion of the side edges of the top surface. The inner bottom surface joins the lower edge of the inner side surface. The outer bottom surface joins the lower edge of the outer side surface. A lower cushion supports the lower punch and is fixed to the bed.

The outer lower jig is positioned adjacent to the outer bottom surface of the lower punch and fixed to the bed. The outer lower jig has an outer lower blade on the edge of the upper surface of the outer lower jig adjacent to the outer bottom surface of the lower punch. The outer lower jig has an outer groove formed on its upper surface along the curved outer side edge of the curved portion. The upper pad is arranged to face the top surface of the lower punch. The upper pad is supported by the slide via elastic members.

The upper die is fixed to the slide. The upper die has an inner wall surface, an outer wall surface, an inner lower surface, an outer lower surface, and an outer recess. The inner wall surface corresponds to the inner side surface of the lower punch. The outer wall surface corresponds to the outer side surface of the lower punch. The inner bottom surface faces the inner bottom surface of the lower punch. The outer lower surface faces the outer bottom surface of the lower punch. The outer recess abuts the outer lower surface. The upper die has an outer upper edge on the edge of the outer lower surface adjacent to the outer recess. The upper die has an outer ridge projecting from the outer bottom surface at a position facing the outer groove on the bottom surface of the outer concave portion.

A method of manufacturing a press-formed product according to another embodiment of the present invention is a manufacturing method using the press apparatus of the other embodiment. A press-formed product manufactured by the manufacturing method includes an elongated top plate, an inner vertical wall, an outer vertical wall, an inner flange, and an outer flange. The top plate has a curved portion that curves in-plane. The inner vertical wall connects to the curved inner side edge of the curved portion of the side edges of the top plate. The outer vertical wall connects to the curved outer side edge of the curved portion of the both side edges of the top plate. The inner flange joins the lower edge of the inner longitudinal wall. The outer flange joins the lower edge of the outer longitudinal wall.

The manufacturing method includes steps (a) to (e). In step (a), a blank made of a metal plate is prepared. The blank has a size exceeding the installation area of the outer ridges of the upper die. In step (b), the blank is placed on top of the lower punch. In step (c), the slide is lowered to clamp the blank between the upper pad and the top surface of the lower punch. In step (d), the slide is further lowered, and the blank is pressed by the upper die and the lower punch, and by the outer ridge and the outer groove. In step (e), the slide is further lowered to cut the blank by the outer upper and lower outer blades.

According to the press apparatus and the method for manufacturing a press-formed product according to the embodiment of the present invention, when manufacturing a press-formed product that is long and has a hat-shaped cross section and includes a curved portion in a plan view. , can effectively suppress torsion and wall warpage.

FIG. 1A is a perspective view showing the appearance of a press-molded product. FIG. 1B is a plan view showing the appearance of a press-formed product. FIG. 1C is a perspective view showing the appearance of another press-molded product. FIG. 2A is a plan view showing variations of press-formed products. FIG. 2B is a plan view showing a variation of the press-formed product. FIG. 2C is a plan view showing a variation of the press-formed product. FIG. 2D is a plan view showing a variation of the press-formed product. FIG. 2E is a plan view showing a variation of the press-formed product. FIG. 2F is a plan view showing a variation of the press-formed product. FIG. 2G is a plan view showing a variation of the press-formed product. FIG. 3A is a plan view showing stress generated in a plank during press forming by general press working. FIG. 3B is a perspective view showing stress generated in a press-formed product at the completion of press-forming by general press working. FIG. 3C is a perspective view showing stress generated by springback in a molded article taken out from a mold after press molding by general press working. FIG. 4A is a cross-sectional view showing stress generated in a blank during press forming by general press working. FIG. 4B is a cross-sectional view showing stress generated in a press-molded product taken out from a mold after press-molding by general press working. FIG. 4C is a cross-sectional view showing a press-formed product before and after springback occurs when the press-formed product is formed by general press working. FIG. 5 is a perspective view showing a press-formed product in which twisting and wall warpage have occurred. FIG. 6 is a cross-sectional view showing an example of the pressing device of the first embodiment. 7 is a perspective view of a mold set provided in the pressing device shown in FIG. 6. FIG. FIG. 8A is a cross-sectional view showing one step in the method of manufacturing a press-formed product using the press apparatus of the first embodiment. FIG. 8B is a cross-sectional view showing a step following FIG. 8A. FIG. 8C is a cross-sectional view showing a step following FIG. 8B. FIG. 8D is a cross-sectional view showing a step following FIG. 8C. FIG. 8E is a cross-sectional view showing a step following FIG. 8D. FIG. 8F is a cross-sectional view showing a step following FIG. 8E. FIG. 9 is a plan view showing a blank applied to the method of manufacturing a press-formed product using the pressing device of the first embodiment. FIG. 10 is a plan view for explaining the situation when a press-formed product is formed by the manufacturing method using the press apparatus of the first embodiment. FIG. 11 is a cross-sectional view showing an example of the press device of the second embodiment. FIG. 12 is a plan view showing a blank applied to the method of manufacturing a press-formed product using the press device of the second embodiment. FIG. 13 is a plan view of the blank. FIG. 14 is a cross-sectional view showing a state during press molding. FIG. 15 is a plan view showing a preferred shape 1 of the blank. FIG. 16 is a plan view for explaining the situation when the blank shown in FIG. 15 is formed into a press-formed product. FIG. 17 is a diagram showing the relationship between .theta.2/.theta.1 and the twist angle of the press-formed product. FIG. 18 is a plan view showing a preferred shape 2 of the blank. FIG. 19 is a plan view showing a preferred shape 3 of the blank. FIG. 20 is a plan view for explaining the situation when the blank shown in FIG. 19 is formed into a press-formed product. FIG. 21 is a diagram showing the relationship between .theta.3/.theta.1 and the twist angle of the press-formed product. FIG. 22 is a plan view showing a preferred shape 4 of the blank. FIG. 23 is a cross-sectional view for explaining preferred dimensions of the inner and outer ridges. FIG. 24 is a cross-sectional view for explaining preferred dimensions of the inner lower jig and the outer lower jig. FIG. 25 is a cross-sectional view for explaining preferred initial height positions of the inner bottom surface and the outer bottom surface of the lower punch. FIG. 26 is a cross-sectional view for explaining a suitable amount of descent of the lower punch and suitable depths of the inner and outer recesses of the upper die. FIG. 27A shows a preferred shape of the inner bedknife. Figure 27B shows a preferred shape for the outer bedknife. FIG. 28A is a perspective view for explaining a torsion evaluation method. FIG. 28B is a cross-sectional view for explaining a wall warpage evaluation method.

Embodiments of the present invention will be described below. In addition, in the following description, although an embodiment of the present invention will be described with an example, the present invention is not limited to the example described below. Although specific numerical values and specific materials may be exemplified in the following description, the present invention is not limited to those exemplifications.

In order to solve the above-mentioned problems, the present inventors studied in detail the mechanism of twisting and wall warping during the production of press-formed products. As a result, the following findings were obtained. In this specification, the press-formed product includes a portion that is elongated, has a hat-shaped cross section, and is curved in a plan view.

[Press molded product]
1A and 1B are diagrams showing the appearance of a press-formed product 101. FIG. Of these figures, FIG. 1A is a perspective view and FIG. 1B is a plan view. Referring to FIGS. 1A and 1B, a press-formed product 101 is elongated and has a hat-shaped cross section. The press-formed product 101 includes a portion (hereinafter also referred to as “curved portion”) 111 that curves in plan view. Furthermore, the press-formed product 101 includes a linear portion 112 that extends linearly from the longitudinal end of the curved portion 111 . In this specification, the cross section means a cross section perpendicular to the longitudinal direction of the press-formed product 101 . The longitudinal direction means the direction in which the press-formed product 101 extends. Transverse means the direction perpendicular to the longitudinal direction. Further, when a section and directions are shown in a press apparatus 1 for forming the press-formed product 101 , which will be described later, the section and directions match those of the press-formed product 101 . For example, in the press device 1, the direction in which the top surface 41 of the lower punch 4 extends is the longitudinal direction, and the cross section perpendicular to the direction in which the top surface 41 of the lower punch 4 extends is the cross section.

The press-formed product 101 includes a top plate 102, an inner vertical wall 103i, an outer vertical wall 103o, an inner flange 104i, and an outer flange 104o. The top plate 102 is elongated and flat and has a curved portion 121 . The curved portion 121 of the top plate 102 is a portion that curves within the flat surface of the top plate 102 . The curved portion 121 of the top plate 102 is included in the curved portion 111 of the press-formed product 101 . In addition, the top plate 102 of the press-formed product 101 shown in FIGS. 1A and 1B has linear portions 122 extending linearly in the longitudinal direction from both ends of the curved portion 121 of the top plate 102 . The straight portion 122 of the top plate 102 is included in the straight portion 112 of the press-formed product 101 .

The inner vertical wall 103i connects to the curved inner side edge 121i of the curved portion 121 among the side edges of the top plate 102 . The inside of the curve here means the center side of the radius of curvature of the curve with respect to one curved portion 121 . When the term "inwardly curved" is used for other elements, it is interpreted in the same way. The inner vertical wall 103i has a curved portion 131i. A curved portion 131i of the inner vertical wall 103i is a portion connected to the curved portion 121 of the top plate 102 and is curved concavely. In other words, the curved portion 131i of the inner vertical wall 103i is convexly curved outward in the plate thickness direction. The curved portion 131 i of the inner vertical wall 103 i is included in the curved portion 111 of the press-formed product 101 . In addition, the inner vertical wall 103i has linear portions 132i that linearly extend in the longitudinal direction from both ends of the curved portion 131i of the inner vertical wall 103i. A straight portion 132 i of the inner vertical wall 103 i connects to the straight portion 122 of the top plate 102 . The straight portion 132 i of the inner vertical wall 103 i is included in the straight portion 112 of the press-formed product 101 .

Outer vertical wall 103 o connects to curved outer side edge 121 o of curved portion 121 of both side edges of top plate 102 . The curved outer side referred to here means the side opposite to the center of the radius of curvature of the curve with respect to one curved portion 121 . When the term "curved outward" is used for other elements, it is interpreted in the same way. The outer vertical wall 103o has a curved portion 131o. A curved portion 131o of the outer vertical wall 103o is a portion connected to the curved portion 121 of the top plate 102 and is curved convexly. In other words, the curved portion 131o of the outer vertical wall 103o is convexly curved outward in the plate thickness direction. The curved portion 131 o of the outer vertical wall 103 o is included in the curved portion 111 of the press-formed product 101 . In addition, the outer vertical wall 103o has linear portions 132o extending linearly in the longitudinal direction from both ends of the curved portion 131o of the outer vertical wall 103o. A straight portion 132 o of the outer vertical wall 103 o connects to the straight portion 122 of the top plate 102 . The straight portion 132 o of the outer vertical wall 103 o is included in the straight portion 112 of the press-formed product 101 .

The inner flange 104i connects to the lower edge of the inner vertical wall 103i. The inner flange 104i has a curved portion 141i. A curved portion 141i of the inner flange 104i joins a curved portion 131i of the inner vertical wall 103i. The curved portion 141 i of the inner flange 104 i is included in the curved portion 111 of the press-formed product 101 . In addition, the inner flange 104i has linear portions 142i extending linearly in the longitudinal direction from both ends of the curved portion 141i of the inner flange 104i. The straight portion 142i of the inner flange 104i connects to the straight portion 132i of the inner vertical wall 103i. The straight portion 142 i of the inner flange 104 i is included in the straight portion 112 of the press-formed product 101 .

The outer flange 104o connects to the lower edge of the outer vertical wall 103o. The outer flange 104o has a curved portion 141o. A curved portion 141o of the outer flange 104o joins a curved portion 131o of the outer vertical wall 103o. The curved portion 141 o of the outer flange 104 o is included in the curved portion 111 of the press-formed product 101 . In addition, the outer flange 104o has linear portions 142o extending linearly in the longitudinal direction from both ends of the curved portion 141o of the outer flange 104o. A straight portion 142o of the outer flange 104o connects to a straight portion 132o of the outer vertical wall 103o. The straight portion 142 o of the outer flange 104 o is included in the straight portion 112 of the press-formed product 101 .

As shown in FIG. 1C, a fillet R may be formed at the corner portion between the top plate 102 and the inner vertical wall 103i. This corner portion is a portion that connects the side edge 121i of the top plate 102 and the upper edge of the inner vertical wall 103i. Fillet R means the radius of curvature appearing in the cross section of the corner. The same applies to the corner portion between the inner vertical wall 103i and the inner flange 104i, the corner portion between the top plate and the outer vertical wall 103o, and the corner portion between the outer vertical wall 103o and the outer flange 104o. In FIG. 1A, for the sake of simplicity, a shape with no fillet R, that is, a shape with 0 (zero) fillet R is shown. In addition, for the sake of simplicity, the following figures also show the shape without the fillet R at each corner.

A press-formed product 101 shown in FIGS. 1A and 1B is composed of a curved portion 111 and straight portions 112 linearly extending from both ends of the curved portion 111 in the longitudinal direction. The curved portion 111 of the press-formed product 101 includes the curved portion 121 of the top plate 102, the curved portion 131i of the inner vertical wall 103i, the curved portion 131o of the outer vertical wall 103o, the curved portion 141i of the inner flange 104i, and the curved portion 141i of the outer flange 104o. It is composed of a portion 141o. The straight portion 112 of the press-formed product 101 includes the straight portion 122 of the top plate 102, the straight portion 132i of the inner vertical wall 103i, the straight portion 132o of the outer vertical wall 103o, the straight portion 142i of the inner flange 104i, and the straight portion of the outer flange 104o. It is composed of a portion 142o. However, the press-formed product 101 may be composed only of the curved portion 111 or may be composed of the curved portion 111 and one straight portion 112 .

2A to 2G illustrate variations of the press-formed product 101. FIG. 2A to 2G show plan views of the top plate 102 of the press-molded product 101. FIG.

The top plate 102 shown in FIGS. 2A to 2D is composed of only one curved portion 121. FIG. In other words, the press-formed product 101 shown in FIGS. 2A to 2D consists of only one curved portion 111. As shown in FIG. In the case of the top plate 102 shown in FIG. 2A, the side edge 121i (121o) of the curved portion 121 is configured by one circular arc in plan view. In the case of the top plate 102 shown in FIG. 2B, the side edge 121i (121o) of the curved portion 121 is composed of two circular arcs having mutually different curvature radii in plan view. The two circular arcs are smoothly connected to each other. In the case of the top plate 102 shown in FIG. 2C, the side edge 121i (121o) of the curved portion 121 is configured by one elliptical arc in plan view. In the case of the top plate 102 shown in FIG. 2D, the side edges 121i (121o) of the curved portion 121 are composed of two elliptical arcs of mutually different sizes in plan view. The two elliptical arcs are gently connected to each other. In plan view, the side edges 121i (121o) of the curved portion 121 may be other curves (eg, spline curve, Bezier curve).

The top plate 102 shown in FIG. 2E is composed of one curved portion 121 and one straight portion 122 . In other words, the press-formed product 101 shown in FIG. 2E is composed of one curved portion 111 and one straight portion 112 . In the case of the top plate 102 shown in FIG. 2E, a straight portion 122 is provided at one end of the curved portion 121 . A side edge 121i (121o) of the curved portion 121 smoothly connects to a side edge of the straight portion 122 .

The top plate 102 shown in FIG. 2F is composed of one curved portion 121 and two straight portions 122 . In other words, the press-formed product 101 shown in FIG. 2F is composed of one curved portion 111 and two straight portions 112 . In the case of the top plate 102 shown in FIG. 2F , straight portions 122 are provided at both ends of the curved portion 121 . A side edge 121i (121o) of the curved portion 121 smoothly connects to a side edge of each straight portion 122 .

The top plate 102 shown in FIG. 2G is composed of two curved portions 121 and one straight portion 122 . In other words, the press-formed product 101 shown in FIG. 2G is composed of two curved portions 111 and one straight portion 112 . In the case of the top plate 102 shown in FIG. 2G, curved portions 121 are provided at both ends of the linear portion 122 . The side edge of the straight portion 122 smoothly connects to the side edge 121i (121o) of each curved portion 121 .

Such a press-formed product 101 is formed by press working such as squeezing or bending. Generally, a lower punch and an upper die are used as dies for press working. A lower punch, an upper die and an upper pad may be used as the mold. The situation when forming the press-formed product 101 using such a mold will be described below.

[Manufacturing of press-formed products by general press working]
3A to 3C are diagrams for explaining the situation when the press-formed product 101 is formed by general press working. Of these figures, FIG. 3A is a plan view showing stresses occurring in the blank 1201 during press forming. FIG. 3B is a perspective view showing stress generated in the press-formed product 101 when press-forming is completed. FIG. 3C is a perspective view showing stress generated in the press-molded product 101 taken out from the mold after press-molding.

In FIG. 3A, the blank 1201 is indicated by a solid line, and the press-formed product 101 molded from this blank 1201 is indicated by a two-dot chain line. In addition, in FIG. 3A, the longitudinal stress generated in the regions of the inner vertical wall 103i, the inner flange 104i, the outer vertical wall 103o, and the outer flange 104o of the press-formed product 101 is indicated by thick solid arrows. In FIG. 3B, the stress during forming that occurs in the inner vertical wall 103i and the outer vertical wall 103o of the press-formed product 101 is indicated by thick solid arrows, and occurs in the inner flange 104i and the outer flange 104o of the press-formed product 101. Stresses during forming are indicated by thin solid arrows. In FIG. 3C, the stress generated by springback after releasing the mold from the inner vertical wall 103i and the outer vertical wall 103o of the press-formed product 101 is indicated by a thick solid arrow. and the stress generated by springback in the outer flange 104o is indicated by thin solid arrows. The direction of each arrow represents the direction in which stress acts.

Referring to FIG. 3A, in the blank 1201 being press-molded, a region corresponding to the curved inner side of the curved portion 121 of the top plate 102 undergoes stretch-flange deformation. That is, the region that is the inner portion of the curve of the curved portion 121 of the top plate 102 undergoes stretch-flange deformation. This is because the circumferential length (longitudinal length) of this region increases during press molding. On the other hand, in the blank 1201 being press-molded, the area corresponding to the curved outer side of the curved portion 121 of the top plate 102 undergoes contraction flange deformation. In other words, the region of the curved portion 121 of the top plate 102 on the outer side of the curve is contracted and deformed into a flange. This is because the peripheral length (longitudinal length) of this region becomes smaller during press molding.

In this case, in the blank 1201 being press-formed, tensile stress is generated in the longitudinal direction in the regions to be the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i. This is because this region undergoes stretch-flange deformation. On the other hand, in the blank 1201 being press-molded, compressive stress is generated in the longitudinal direction in the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o. This is because this region undergoes contraction flange deformation.

Then, as shown in FIG. 3B, in the press-formed product 101 in the mold when press-forming is completed, tensile stress is generated in the longitudinal direction in the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i. . This is because the curved portion 131i and the curved portion 141i are formed by stretch-flange deformation and restrained by the mold in a state in which tensile stress in the longitudinal direction is generated. On the other hand, in the press-formed product 101 in the mold after completion of press-forming, compressive stress is generated in the longitudinal direction in the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o. This is because the curved portion 131o and the curved portion 141o are formed by contraction flange deformation, and are constrained by the mold in a state where compressive stress in the longitudinal direction is generated.

When the press-molded product 101 is removed from the mold after press-molding, the restraint by the mold is released. Therefore, springback occurs in the press-formed product 101 . That is, as shown in FIG. 3C, the tensile stress at the completion of press forming is reversed in the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i, and compressive stress is generated in the longitudinal direction. On the other hand, in the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o, the compressive stress at the completion of press forming is reversed, and tensile stress is generated in the longitudinal direction.

In short, in the press-formed product 101, due to springback, longitudinal compressive stress is generated in the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i, and the curved portion 131o of the outer vertical wall 103o and the outer flange 104o are compressed. A tensile stress in the longitudinal direction is generated in the curved portion 141o. Therefore, the entire press-formed product 101 is twisted. That is, the press-formed product 101 is twisted due to the compressive stress in the longitudinal direction generated in the curved inner part of the curved portion of the press-formed product 101 . In addition, twisting of the press-formed product 101 occurs due to the tensile stress in the longitudinal direction that is generated in the curved outer portion of the curved portion of the press-formed product 101 .

4A to 4C are diagrams for explaining the situation when the press-formed product 101 is formed by bending, which is a general press work, from a different perspective from the situation shown in FIGS. 3A to 3C. . Of these figures, FIG. 4A is a cross-sectional view showing stresses occurring in blank 1201 during press forming. FIG. 4B is a cross-sectional view showing the stress generated in the press-molded product due to springback when it is removed from the mold after press-molding. FIG. 4C is a cross-sectional view showing the press-formed product 101 before and after springback occurs.

4A to 4C show cross sections of the press-formed product 101 at the curved portion. In addition, in FIG. 4A, the stresses generated in the regions that become the inner vertical wall 103i and the outer vertical wall 103o of the press-formed product 101 are indicated by solid line arrows. In FIG. 4B, the stresses generated in the inner vertical wall 103i and the outer vertical wall 103o of the press-formed product 101 are indicated by solid line arrows. In FIG. 4C, the press-formed product 101 before springback is indicated by a two-dot chain line, and the press-formed product 101 after springback is indicated by a solid line. The direction of each arrow represents the direction in which stress acts.

Referring to FIG. 4A, a lower punch 1004, an upper die 1008 and an upper pad 1007 are used as a mold for press working. In this case, first, the blank 1201 is sandwiched between the upper pad 1007 and the lower punch 1004 by lowering the slide (not shown). Thereafter, further descent of the slide gradually shapes the inner longitudinal wall 103i and the outer longitudinal wall 103o. At that time, the inner vertical wall 103 i and the outer vertical wall 103 o are bent and deformed by the die shoulder 1086 of the upper die 1008 . As a result, a tensile stress is generated in the lateral direction (height direction) on the outer surface of the region that will become the inner vertical wall 103i. On the other hand, compressive stress is generated in the lateral direction (height direction) on the inner surface of the region that will become the inner vertical wall 103i. A phenomenon similar to that of the inner vertical wall 103i also occurs in the region that becomes the outer vertical wall 103o. That is, a tensile stress is generated in the lateral direction (height direction) on the outer surface of the region that will be the outer vertical wall 103o. On the other hand, compressive stress is generated in the lateral direction (height direction) on the inner surface of the region that will become the outer vertical wall 103o. In these regions, the outer surface means the surface that contacts the upper die 1008 (especially the die shoulder 1086) and the inner surface means the surface that contacts the lower punch 1004.

Then, in the press-formed product 101 in the mold when press-forming is completed, tensile stress is generated in the lateral direction on the outer surfaces of the inner vertical wall 103i and the outer vertical wall 103o. This is because the inner vertical wall 103i and the outer vertical wall 103o are restrained by the mold while tensile stress in the transverse direction is generated on each outer surface. On the other hand, in the press-molded product 101 in the mold after press-molding is completed, compressive stress is generated in the lateral direction on the inner surfaces of the inner vertical wall 103i and the outer vertical wall 103o. This is because the inner vertical wall 103i and the outer vertical wall 103o are restrained by the mold while a compressive stress in the lateral direction is generated on each inner surface.

When the press-molded product 101 is removed from the mold after press-molding, the restraint by the mold is released. Therefore, springback occurs in the press-formed product 101 . That is, as shown in FIG. 4B, the tensile stress at the time of completion of press forming is reversed on the outer surfaces of the inner vertical wall 103i and the outer vertical wall 103o, and compressive stress is generated in the lateral direction. On the other hand, on the inner surfaces of the inner vertical wall 103i and the outer vertical wall 103o, the compressive stress at the completion of press forming is reversed, and tensile stress is generated in the lateral direction.

In short, in the press-formed product 101, a compressive stress in the lateral direction is generated on the outer surfaces of the inner vertical wall 103i and the outer vertical wall 103o due to the springback, and the inner vertical wall 103i and the outer vertical wall 103o each generate a lateral compressive stress. directional tensile stress occurs. In this way, stresses in different directions are generated on the outer surface and the inner surface. Due to this stress difference, the inner vertical wall 103i and the outer vertical wall 103o respectively warp outward as shown in FIG. 4C. In other words, due to the difference between the compressive stress in the lateral direction generated on the outer surface of the inner vertical wall 103i and the tensile stress in the lateral direction generated on the inner surface of the inner vertical wall 103i, wall warp in the inner vertical wall 103i of the press-formed product 101 occurs. In addition, due to the difference between the compressive stress in the lateral direction generated on the outer surface of the outer vertical wall 103o and the tensile stress in the lateral direction generated on the inner surface of the outer vertical wall 103o, the wall warp of the outer vertical wall 103o of the press-formed product 101 occurs.

FIG. 5 is a perspective view showing a press-formed product 101 in which twisting and wall warpage have occurred. In FIG. 5, the press-formed product 101 in which no twisting and wall warpage have occurred is indicated by a chain double-dashed line. With reference to FIG. 5, as described above, the press-formed product 101 undergoes twisting and wall warpage due to springback in general press working.

[Examination of suppression of torsion and wall warpage]
As described above, when the press-formed product 101 is removed from the mold after press-molding and the restraint by the mold is released, the longitudinal compressive stress generated in the curved inner portion of the curved portion of the press-formed product 101 causes the press Twisting of the molded product 101 occurs. That is, the press-formed product 101 is twisted by longitudinal compressive stress generated in the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i. Further, when the press-molded product 101 is removed from the mold after press-molding and the restraint by the mold is released, the longitudinal tensile stress generated in the curved outer portion of the curved portion of the press-molded product 101 causes the press-molded product to 101 torsion occurs. That is, the press-formed product 101 is twisted by longitudinal tensile stress generated in the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o.

Further, when the press-molded product 101 is removed from the mold after press molding and the restraint by the mold is released, the compressive stress in the lateral direction generated on the outer surface of the inner vertical wall 103i and the short stress generated on the inner surface of the inner vertical wall 103i. The wall warpage of the press-formed product 101 occurs due to the difference between the tensile stress in the hand direction and the tension stress in the hand direction. The wall warpage of the press-formed product 101 occurs due to the difference between the lateral compressive stress generated on the outer surface of the outer vertical wall 103o and the lateral tensile stress generated on the inner surface of the outer vertical wall 103o.

Therefore, in order to suppress the twisting of the press-formed product 101, it is sufficient to reduce the longitudinal tensile stress generated in the curved inner portion of the curved portion of the press-formed product 101 when the press-formed product 101 is completely formed. The curved inner portions of the curved portion of the press-formed product 101 are the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i. In order to suppress the twisting of the press-formed product 101, it is sufficient to reduce the longitudinal compressive stress generated in the curved outer portion of the curved portion of the press-formed product 101 when the press-formed product 101 is completely formed. The curved outer portions of the curved portion of the press-formed product 101 are the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o. In order to further suppress twisting of the press-formed product 101, both the tensile stress and the compressive stress should be reduced.

In order to suppress the wall warp in the inner vertical wall 103i of the press-formed product 101, when the press-formed product 101 is completed, the tensile stress in the lateral direction generated on the outer surface of the inner vertical wall 103i and the stress on the inner surface of the inner vertical wall 103i It suffices if the difference between the generated compressive stress in the lateral direction and the stress can be reduced. In addition, in order to suppress the wall warp in the outer vertical wall 103o of the press-formed product 101, when the molding of the press-formed product 101 is completed, the tensile stress in the lateral direction generated on the outer surface of the outer vertical wall 103o and the stress of the outer vertical wall 103o It suffices if the difference between the compressive stress in the lateral direction generated on the inner surface can be reduced.

Thus, the present inventors investigated the mechanism of twisting and wall warping when manufacturing the press-formed product 101 and found a direction for suppressing the twisting and wall warping of the press-formed product 101 . The present inventors have studied a press apparatus and a method of manufacturing the press-formed product 101 that are suitable for this direction. As a result of intensive studies, the following findings were obtained.

In a typical press forming blank 1201 , the areas that will become the inner longitudinal walls 103 i and inner flanges 104 i are simply drawn toward the area that will become the top plate 102 . Similarly, the area that will become the outer vertical wall 103 o and the outer flange 104 o will simply be drawn towards the area that will become the top plate 102 .

The stretch-flange deformed portion, that is, the inner curved portion of the curved portion of the press-formed product 101 (the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i) is a region that becomes that portion during press molding. In addition, by applying a tension that resists the pulling force toward the area that becomes the top plate 102 and completing the molding of the press-formed product 101 while applying the tension, the tensile stress in the longitudinal direction can be reduced, and in the lateral direction The difference between tensile stress and compressive stress can be reduced. This is because the application of tension during press molding imparts compressive stress in the longitudinal direction as a component force in the longitudinal direction, and as a result, the tensile stress in the longitudinal direction associated with stretch-flange deformation is alleviated. In order to apply the tension, a surplus inner trough that does not become the final product is formed inside the curved portion 141i of the inner flange 104i during press molding. The inner valley is formed along the curved inner side edge 121 i of the curved portion 121 of the top plate 102 .

However, if the inner valley portion still exists after the completion of press forming, the inner valley portion will be twisted. This is because the inner valley corresponds to the press-formed product 101 of small size. In this case, the press-formed product 101 as a product may be twisted as the inner valley is twisted. Therefore, at least before removing the press-formed product 101 from the mold, the region including the inner valley is removed from the press-formed product 101 .

In this way, the inner portion of the curved portion of the press-formed product 101 (the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i) of the press-formed product 101 accommodated in the mold has a longitudinal direction Tensile stress can be reduced, and in the transverse direction, the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be reduced. As a result, the compressive stress in the longitudinal direction can be reduced in the curved inner portion of the curved portion of the press-formed product 101 removed from the mold, and the difference between the compressive stress on the outer surface and the tensile stress on the inner surface can be reduced in the lateral direction. can be reduced. As a result, twisting and wall warping of the press-formed product 101 can be effectively suppressed.

In addition, for the portions that undergo shrinkage flange deformation, that is, the outer curved portions of the curved portion of the press-formed product 101 (the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o), during press-molding By applying a tension to the region to be the top plate 102 to resist the pulling force toward the region to be the top plate 102 and completing the molding of the press-formed product 101 while applying the tension, the compressive stress in the longitudinal direction can be reduced, direction can reduce the difference between tensile and compressive stress. This is because the application of tension during press molding imparts tensile stress in the longitudinal direction as a component of force in the longitudinal direction, and as a result, the compressive stress in the longitudinal direction associated with contraction flange deformation is alleviated. In order to achieve the application of tension, a surplus outer trough portion that does not become the final product is formed further outward from the curved portion 141o of the outer flange 104o during press molding. This outer valley is formed along the curved outer side edge 121 o of the curved portion 121 of the top plate 102 .

However, if the outer troughs still exist after the completion of press forming, the outer troughs will be twisted. This is because the outer valley corresponds to the small-sized press-formed product 101 . In this case, the press-formed product 101, which is a product, may be twisted along with the twisting of the outer valley. Therefore, at least before removing the press-formed product 101 from the mold, the region including the outer valley is removed from the press-formed product 101 .

In this way, in the curved outer portion (the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o) of the curved portion of the press-formed product 101 in the state of being accommodated in the mold, the longitudinal direction Compressive stress can be reduced, and in the transverse direction, the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be reduced. As a result, the tensile stress in the longitudinal direction can be reduced in the curved outer portion of the curved portion of the press-formed product 101 taken out from the mold, and the difference between the compressive stress on the outer surface and the tensile stress on the inner surface can be reduced in the lateral direction. can be reduced. As a result, twisting and wall warping of the press-formed product 101 can be effectively suppressed.

However, if both the inner valley and the outer valley are formed during press molding, and both the inner recess and the outer recess are removed from the press-molded product 101 at least before removing the press-molded product 101 from the mold, press-molding can be achieved. Twisting of the product 101 and wall warping can be further suppressed.

The present invention has been completed based on the above findings.

A press apparatus according to one embodiment of the present invention comprises a bed, a slide, a lower punch, a lower cushion, an inner lower jig, an upper pad and an upper die. The slide can be raised and lowered with respect to the bed. The lower punch has an elongated top surface, an inner side surface, an outer side surface, an inner bottom surface, and an outer bottom surface. The top surface has an in-plane curvature. The inner side surface connects to the curved inner side edge of the curved portion of the side edges of the top surface. The outer side surface connects to the curved outer side edge of the curved portion of the side edges of the top surface. The inner bottom surface joins the lower edge of the inner side surface. The outer bottom surface joins the lower edge of the outer side surface. A lower cushion supports the lower punch and is fixed to the bed.

The inner lower jig is arranged adjacent to the inner bottom surface of the lower punch and fixed to the bed. The inner lower jig has an inner lower blade on the edge of the upper surface of the inner lower jig adjacent to the inner bottom surface of the lower punch. The inner lower jig has an inner groove formed on its upper surface along the curved inner side edge of the curved portion. The upper pad is arranged to face the top surface of the lower punch. The upper pad is supported by the slide via elastic members.

The upper die is fixed to the slide. The upper die has an inner wall surface, an outer wall surface, an inner lower surface, an outer lower surface, and an inner recess. The inner wall surface corresponds to the inner side surface of the lower punch. The outer wall surface corresponds to the outer side surface of the lower punch. The inner bottom surface faces the inner bottom surface of the lower punch. The outer lower surface faces the outer bottom surface of the lower punch. The inner recess is adjacent to the inner lower surface. The upper die has an inner upper blade on the edge of the inner lower surface adjacent to the inner recess. The upper die has an inner ridge projecting from the inner bottom surface at a position facing the inner groove on the bottom surface of the inner recess (first configuration).

According to the press device having the first configuration, press molding is performed by lowering the slide. During press molding, the press-formed product 101 is formed by the lower punch, the upper die and the upper pad, and the curved portion of the press-formed product 101 is further curved by the inner ridge of the upper die and the inner groove of the inner lower jig. Inwardly, excess inner valleys are molded that do not become the final product. Then, the inner upper blade of the upper die and the inner lower blade of the inner lower jig cut the boundary between the press-formed product 101 and the region including the inner valley. As a result, the region including the inner valley is removed from the press-formed product 101 .

In the process of forming the inner valley portion during press molding, in the region that will be the inner curved portion of the curved portion of the press-formed product 101 (the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i), A tension is applied to resist the pulling force toward the area that will become the top plate 102 . In this case, by applying tension, compressive stress is applied in the longitudinal direction as a component of force in the longitudinal direction, and as a result, tensile stress in the longitudinal direction associated with stretch-flange deformation is alleviated. Therefore, the tensile stress in the longitudinal direction can be reduced, and the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be reduced in the lateral direction. Furthermore, the inner valley is removed during the press forming process. By applying such tension and removing the inner valley, the inner curved portion of the curved portion of the press-formed product 101 removed from the mold (the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i) ), the compressive stress in the longitudinal direction caused by springback can be reduced, and the difference between the compressive stress on the outer surface and the tensile stress on the inner surface can be reduced in the transverse direction. As a result, twisting and wall warping of the press-formed product 101 can be effectively suppressed.

A press apparatus according to another embodiment of the present invention comprises a bed, a slide, a lower punch, a lower cushion, an outer lower jig, an upper pad and an upper die. The slide can be raised and lowered with respect to the bed. The lower punch has an elongated top surface, an inner side surface, an outer side surface, an inner bottom surface, and an outer bottom surface. The top surface has an in-plane curvature. The inner side surface connects to the curved inner side edge of the curved portion of the side edges of the top surface. The outer side surface connects to the curved outer side edge of the curved portion of the side edges of the top surface. The inner bottom surface joins the lower edge of the inner side surface. The outer bottom surface joins the lower edge of the outer side surface. A lower cushion supports the lower punch and is fixed to the bed.

The outer lower jig is positioned adjacent to the outer bottom surface of the lower punch and fixed to the bed. The outer lower jig has an outer lower blade on the edge of the upper surface of the outer lower jig adjacent to the outer bottom surface of the lower punch. The outer lower jig has an outer groove formed on its upper surface along the curved outer side edge of the curved portion. The upper pad is arranged to face the top surface of the lower punch. The upper pad is supported by the slide via elastic members.

The upper die is fixed to the slide. The upper die has an inner wall surface, an outer wall surface, an inner lower surface, an outer lower surface, and an outer recess. The inner wall surface corresponds to the inner side surface of the lower punch. The outer wall surface corresponds to the outer side surface of the lower punch. The inner bottom surface faces the inner bottom surface of the lower punch. The outer lower surface faces the outer bottom surface of the lower punch. The outer recess abuts the outer lower surface. The upper die has an outer upper edge on the edge of the outer lower surface adjacent to the outer recess. The upper die has an outer ridge projecting from the outer bottom surface at a position facing the outer groove on the bottom surface of the outer concave portion (second configuration).

According to the press device having the second configuration, press molding is performed by lowering the slide. During press molding, the press-formed product 101 is formed by the lower punch, the upper die and the upper pad, and the curved portion of the press-formed product 101 is further curved by the outer ridges of the upper die and the outer grooves of the outer lower jig. Excess outer valleys are molded outwardly that do not form the final product. Then, the outer upper blade of the upper die and the outer lower blade of the outer lower jig cut the boundary between the press-formed product 101 and the region including the outer valley. As a result, the region including the outer valley is removed from the press-formed product 101 .

During press molding, in the process of forming the outer valley portion, in the region that will be the curved outer portion of the curved portion of the press-formed product 101 (the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o), A tension is applied to resist the pulling force toward the area that will become the top plate 102 . In this case, by applying tension, tensile stress is applied in the longitudinal direction as a component force in the longitudinal direction, and as a result, longitudinal compressive stress associated with contraction flange deformation is relieved. Therefore, the compressive stress in the longitudinal direction can be reduced, and the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be reduced in the transverse direction. Additionally, the outer valleys are removed during the press forming process. By applying such tension and removing the inner valley portion, the curved outer portion of the curved portion of the press-formed product 101 removed from the mold (the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o) ), the tensile stress in the longitudinal direction caused by springback can be reduced, and in the lateral direction, the difference between the compressive stress on the outer surface and the tensile stress on the inner surface can be reduced. As a result, twisting and wall warping of the press-formed product 101 can be effectively suppressed.

The pressing device having the first configuration may be combined with the pressing device having the second configuration. In this case, the pressing device having the first configuration further includes an outer lower jig. The outer lower jig is positioned adjacent to the outer bottom surface of the lower punch and fixed to the bed. The outer lower jig has an outer lower blade on the edge of the upper surface of the outer lower jig adjacent to the outer bottom surface of the lower punch. The outer lower jig has an outer groove formed on its upper surface along the curved outer side edge of the curved portion. The upper die also has an outer recess. The outer recess abuts the outer lower surface. The upper die has an outer upper edge on the edge of the outer lower surface adjacent to the outer recess. The upper die has an outer ridge projecting from the outer bottom surface at a position facing the outer groove on the bottom surface of the outer concave portion (third configuration).

A press device having a third configuration is a press device that combines the first configuration and the second configuration. Therefore, according to the pressing device having the third configuration, both the inner and outer valleys are formed during press-forming, and both the inner and outer valleys are removed during the press-forming process. . Therefore, the effect of the press device having the first configuration and the effect of the press device having the second configuration are synergistically manifested, and the torsion and wall warping of the press-formed product 101 can be suppressed more effectively.

In addition, in the lower punch described above, the inner side surface may be directly connected to the top surface, or may be connected to the top surface via a corner portion. The outer side surface may be directly connected to the top surface, or may be connected to the top surface via a corner portion. The inner bottom surface may be directly connected to the inner side surface, or may be connected to the inner side surface via a corner portion. The outer bottom surface may be directly connected to the outer side surface, or may be connected to the outer side surface via a corner portion.

In the press device having the first or third configuration, it is preferable that the protrusion amount of the inner ridge from the inner lower surface is 5 mm or more (fourth configuration).

If the protrusion amount of the inner ridge is 5 mm or more, the inner trough portion of the curved portion of the press-formed product 101 is curved inwardly during the process of forming the inner valley portion by the inner ridge of the upper die and the inner groove of the inner lower jig. Tension is more effectively applied to the areas that will be the parts (the curved portion 131i of the inner longitudinal wall 103i and the curved portion 141i of the inner flange 104i). The protrusion amount of the inner ridge is more preferably 9 mm or more. The upper limit of the protrusion amount of the inner ridge is not particularly limited. However, if the protrusion amount of the inner ridge is 20 mm or more, the effect of suppressing torsion and wall warpage is saturated. Therefore, the preferable upper limit of the protrusion amount of the inner ridge is 20 mm.

In any one of the first, third and fourth configurations of the press device, the width of the inner ridge is preferably 0.8 times or more the height of the inner ridge (fifth configuration).

If the width of the inner ridge is 0.8 times or more the height of the inner ridge, the strength of the inner ridge itself can be sufficiently ensured. In this case, deformation, chipping, etc. of the inner ridge can be suppressed. The width of the inner ridges is more preferably 1.2 times or more the height of the inner ridges. The upper limit of the width of the inner ridge is not particularly limited. However, if the width of the inner ridges exceeds 2.0 times the height of the inner ridges, the strength of the inner ridges does not change and rather the material yield deteriorates. Therefore, it is preferable that the width of the inner ridge is 2.0 times or less the height of the inner ridge.

In the press device of any one of the first, third, fourth and fifth configurations, the inner lower blade is arranged in a longitudinal range corresponding to the curved inner side edge of the curved portion from both ends of the range. is also preferably inclined so that the center of the range is low (sixth configuration).

This inclination of the inner bedknife is the so-called shear angle. In this case, when the region including the inner valley portion is removed from the press-formed product 101 by the inner upper blade of the upper die and the inner lower blade of the inner lower jig, the curved inner side edge of the curved portion of the press-formed product 101 is removed. (The side edges of the curved portion 141i of the inner flange 104i) are not cut at the same time, but are cut gradually from both ends of the side edge toward the center of the side edge. Therefore, the press load required for cutting can be small. Also, during cutting, a compressive stress is applied in the longitudinal direction. Therefore, tensile stress in the longitudinal direction during press molding or at the completion of molding is further alleviated. As a result, the tensile stress in the longitudinal direction during press molding or at the completion of molding can be further reduced, and the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be further reduced in the lateral direction.

In the press apparatus having the second or third configuration, it is preferable that the protrusion amount of the outer protrusion from the outer lower surface is 5 mm or more (seventh configuration).

If the protrusion amount of the outer ridges is 5 mm or more, the outer ridges of the upper die and the outer grooves of the outer lower jig are used to form the outer troughs. Tension is more effectively applied to the areas that will be the parts (the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o). The protrusion amount of the outer ridges is more preferably 9 mm or more. The upper limit of the protrusion amount of the outer ridges is not particularly limited. However, if the projection amount of the outer ridges is 20 mm or more, the effect of suppressing torsion and wall warpage is saturated. Therefore, the preferable upper limit of the protrusion amount of the outer ridges is 20 mm.

In any one of the second, third and seventh configurations of the press device, the width of the outer ridges is preferably 0.8 times or more the height of the outer ridges (eighth configuration).

If the width of the outer ridge is 0.8 times or more the height of the outer ridge, the strength of the outer ridge itself can be sufficiently secured. In this case, it is possible to suppress deformation, chipping, etc. of the outer ridges. The width of the outer ridges is more preferably 1.2 times or more the height of the outer ridges. The upper limit of the width of the outer protrusion is not particularly limited. However, if the width of the outer ridges exceeds 2.0 times the height of the outer ridges, the strength of the outer ridges does not change, and rather the material yield deteriorates. For this reason, it is preferable that the width of the outer ridge is 2.0 times or less the height of the outer ridge.

In the press device of any one of the second, third, seventh and eighth configurations, the outer bedknife is arranged in a longitudinal range corresponding to the curved outer side edge of the curved portion from both ends of the range. is also preferably inclined so that the center of the range is higher (ninth configuration).

This inclination of the outer bedknife is the so-called shear angle. In this case, when removing the region including the outer trough from the press-formed product 101 by the outer upper blade of the upper die and the outer lower blade of the outer lower jig, the curved outer side edge of the curved portion of the press-formed product 101 (The side edge of the curved portion 141o of the outer flange 104o) is not cut at the same time, but is cut gradually from the center of the side edge toward each end of the side edge. Therefore, the press load required for cutting can be small. Also, a tensile stress is applied in the longitudinal direction during cutting. For this reason, the compressive stress in the longitudinal direction during press molding or at the completion of molding is further alleviated. As a result, the compressive stress in the longitudinal direction during press molding or at the completion of molding can be further reduced, and in the lateral direction, the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be further reduced.

A method of manufacturing a press-formed product according to one embodiment of the present invention is a manufacturing method using a press apparatus having any one of the first, third, fourth, fifth and sixth configurations. A press-formed product manufactured by this manufacturing method has an elongated top plate, an inner vertical wall, an outer vertical wall, an inner flange, and an outer flange. The top plate has a curved portion that curves in-plane. The inner vertical wall connects to the curved inner side edge of the curved portion of the side edges of the top plate. The outer vertical wall connects to the curved outer side edge of the curved portion of the both side edges of the top plate. The inner flange joins the lower edge of the inner longitudinal wall. The outer flange joins the lower edge of the outer longitudinal wall.

The manufacturing method includes steps (a) to (e). In step (a), a blank made of a metal plate is prepared. The blank has a size exceeding the installation area of the inner ridge of the upper die. In step (b), the blank is placed on top of the lower punch. In step (c), the slide is lowered to clamp the blank between the upper pad and the top surface of the lower punch. In step (d), the slide is further lowered, and the blank is pressed by the upper die and the lower punch, as well as by the inner ridge and the inner groove. In step (e), the slide is further lowered to cut the blank with the inner upper blade and the inner lower blade (tenth configuration).

In the manufacturing method having the tenth configuration, the press-formed product 101 is manufactured using the pressing device having the first configuration. Therefore, according to the manufacturing method having the tenth configuration, in step (d), the press-formed product 101 is formed by the lower punch, the upper die and the upper pad, and the inner ridge of the upper die and the inner undercut are formed. By the inner groove of the tool, a surplus inner trough that does not become the final product is formed inside the curved portion of the press-formed product 101 . In the process of forming the inner valley portion, the top plate 102 and A tension force is applied to resist the pulling force towards the region. Further, in step (e), the inner upper blade of the upper die and the inner lower blade of the inner lower jig cut the boundary between the press-formed product 101 and the region including the inner valley. As a result, the region including the inner valley is removed from the press-formed product 101 .

Therefore, according to the manufacturing method of the tenth configuration, the curved inner portion of the curved portion of the press-formed product 101 taken out from the mold (the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i) , the longitudinal compressive stress caused by springback can be reduced, and the difference between the compressive stress on the outer surface and the tensile stress on the inner surface can be reduced in the transverse direction. As a result, twisting and wall warping of the press-formed product 101 can be effectively suppressed.

A method of manufacturing a press-formed product according to another embodiment of the present invention is a manufacturing method using a press device having any one of the second, third, seventh, eighth and ninth configurations. A press-formed product manufactured by this manufacturing method has an elongated top plate, an inner vertical wall, an outer vertical wall, an inner flange, and an outer flange. The top plate has a curved portion that curves in-plane. The inner vertical wall connects to the curved inner side edge of the curved portion of the side edges of the top plate. The outer vertical wall connects to the curved outer side edge of the curved portion of the both side edges of the top plate. The inner flange joins the lower edge of the inner longitudinal wall. The outer flange joins the lower edge of the outer longitudinal wall.

The manufacturing method includes steps (a) to (e). In step (a), a blank made of a metal plate is prepared. The blank has a size exceeding the installation area of the outer ridges of the upper die. In step (b), the blank is placed on top of the lower punch. In step (c), the slide is lowered to clamp the blank between the upper pad and the top surface of the lower punch. In step (d), the slide is further lowered, and the blank is pressed by the upper die and the lower punch, and by the outer ridge and the outer groove. In step (e), the slide is further lowered to cut the blank by the outer upper blade and the outer lower blade (eleventh configuration).

In the manufacturing method having the eleventh configuration, the press-formed product 101 is manufactured using the pressing device having the first configuration. Therefore, according to the manufacturing method having the eleventh configuration, in step (d), the press-formed product 101 is formed by the lower punch, the upper die, and the upper pad, and the outer ridges of the upper die and the outer lower molding are formed. By the outer groove of the tool, a surplus outer trough that does not become the final product is formed further outward from the curved portion of the press-formed product 101 . In the process of forming the outer valley portion, the top plate 102 and A tension force is applied to resist the pulling force towards the region. Further, in step (e), the outer upper blade of the upper die and the outer lower blade of the outer lower jig cut the boundary between the press-formed product 101 and the region including the outer valley. As a result, the region including the outer valley is removed from the press-formed product 101 .

Therefore, according to the manufacturing method of the eleventh configuration, the curved outer portion of the curved portion of the press-formed product 101 removed from the mold (the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o) , the tensile stress in the longitudinal direction caused by springback can be reduced, and the difference between the compressive stress on the outer surface and the tensile stress on the inner surface can be reduced in the lateral direction. As a result, twisting and wall warping of the press-formed product 101 can be effectively suppressed.

The manufacturing method of the eleventh configuration may be combined with the manufacturing method of the tenth configuration. The manufacturing method in this case is a manufacturing method using a press apparatus having the third configuration and any one of the fourth to ninth configurations including the third configuration. A press-formed product manufactured by this manufacturing method has an elongated top plate, an inner vertical wall, an outer vertical wall, an inner flange, and an outer flange. The top plate has a curved portion that curves in-plane. The inner vertical wall connects to the curved inner side edge of the curved portion of the side edges of the top plate. The outer vertical wall connects to the curved outer side edge of the curved portion of the both side edges of the top plate. The inner flange joins the lower edge of the inner longitudinal wall. The outer flange joins the lower edge of the outer longitudinal wall.

The manufacturing method includes steps (a) to (e). In step (a), a blank made of a metal plate is prepared. The blank has a size that exceeds the installation area of the inner ridges of the upper die and exceeds the installation area of the outer ridges of the upper die. In step (b), the blank is placed on top of the lower punch. In step (c), the slide is lowered to clamp the blank between the upper pad and the top surface of the lower punch. In step (d), the slide is further lowered to press the blank with the upper die and the lower punch, press the blank with the inner ridges and the inner grooves, and press the blank with the outer ridges and the outer grooves. In step (e), the slide is further lowered to cut the blank with the inner upper blade and the inner lower blade, and cut the blank with the outer upper blade and the outer lower blade (12th configuration).

In the manufacturing method having the twelfth configuration, the press-formed product 101 is manufactured using the pressing device having the third configuration. That is, the manufacturing method of the twelfth configuration is a manufacturing method combining the tenth configuration and the eleventh configuration. Therefore, according to the manufacturing method of the twelfth configuration, the effect of the manufacturing method of the tenth configuration and the effect of the manufacturing method of the eleventh configuration are synergistically manifested, and the press-formed product 101 is more effectively twisted and Wall warpage can be suppressed.

In the manufacturing method of the tenth configuration or the twelfth configuration, in the blank prepared in the step (a), the first region corresponding to at least the central portion in the longitudinal direction of the installation region of the inner ridges of the upper die is the inner ridges. It is preferable that an area outside the both ends of the first area beyond the installation area of the first area is notched (13th configuration).

In this case, no inner valley is formed in the blank in the region of the cutout adjacent to the first region. That is, the cut-out areas do not provide tension. Therefore, the direction of the tension applied during the molding process of the inner valley portion is inclined from the lateral direction. The component force in the longitudinal direction of the tension inclined from the lateral direction becomes larger, and is applied as longitudinal compressive stress. As a result, the tensile stress in the longitudinal direction during press forming that accompanies stretch flanging deformation is more relaxed.

In the manufacturing method of the eleventh configuration or the twelfth configuration, in the blank prepared in the step (a), the second regions corresponding to at least both ends in the longitudinal direction of the installation region of the outer ridges of the upper die are outwardly convex. It is preferable that a region beyond the region where the ridges are provided and located inside the second regions is notched (14th configuration).

In this case, no outer valley is formed in the blank in the region of the cutout adjacent to the second region. That is, the cut-out areas do not provide tension. Therefore, the direction of the tension applied during the molding process of the outer troughs is inclined from the lateral direction. The component force in the longitudinal direction of the tension inclined from the lateral direction becomes larger, and is applied as tensile stress in the longitudinal direction. As a result, the compressive stress in the longitudinal direction during press forming due to shrinkage flange deformation is further alleviated.

The manufacturing method of the 14th configuration may be combined with the manufacturing method of the 13th configuration. The manufacturing method in this case conforms to the manufacturing method of the twelfth configuration. Specifically, in the blank prepared in the step (a), the first region corresponding to at least the central portion in the longitudinal direction of the installation region of the inner ridges of the upper die exceeds the installation region of the inner ridges, and the first region are notched out from the ends of the Further, in the blank prepared in the step (a), the second regions corresponding to at least the longitudinal ends of the installation region of the outer ridges of the upper die exceed the installation region of the outer ridges, and the second regions are separated from each other. The inner region is cut out (15th configuration).

A manufacturing method of the fifteenth configuration is a manufacturing method combining the thirteenth configuration and the fourteenth configuration. Therefore, according to the manufacturing method of the fifteenth configuration, the effect of the manufacturing method of the thirteenth configuration and the effect of the manufacturing method of the fourteenth configuration are synergistically manifested, and the press-formed product 101 is more effectively twisted and Wall warpage can be suppressed.

A specific example of the press apparatus and the method of manufacturing a press-formed product according to the present embodiment will be described below with reference to the drawings. The same reference numerals are given to the same or corresponding parts in the drawings, and the description thereof will not be repeated.

[First embodiment]
[Composition of press device]
FIG. 6 is a cross-sectional view showing an example of the press device 1 of the first embodiment. 7 is a perspective view of a mold set provided in the pressing device shown in FIG. 6. FIG. A press apparatus 1 shown in FIGS. 6 and 7 is used for manufacturing a press-formed product 101 shown in FIGS. 1A and 1B. FIG. 6 shows a cross section of the press-formed product 101 at the position where the curved portion is formed. The right side of FIG. 6 corresponds to the inner side of the curved portion of the press-formed product 101 , and the left side of FIG. 6 corresponds to the outer side of the curved portion of the press-formed product 101 .

6, 7, 1A and 1B, the press apparatus 1 of the first embodiment includes a bed 2, a slide 3, a lower punch 4, a lower cushion 5, and an inner lower jig 6i. , an outer lower jig 6 o , an upper pad 7 and an upper die 8 . A slide 3 is arranged above a fixed bed 2 . The slide 3 can be raised and lowered with respect to the bed 2 . The lower punch 4, the inner lower jig 6i and the outer lower jig 6o constitute a lower mold set for press molding, and the upper pad 7 and the upper die 8 constitute an upper mold set for press molding.

In the press apparatus 1 shown in FIGS. 6 and 7, a lower mold holder 10 is fixed to the upper surface of the bed 2 and an upper mold holder 11 is fixed to the lower surface of the slide 3. As shown in FIG. A lower mold set is held by a lower mold holder 10 . The upper mold set is held by the upper mold holder 11 .

[Lower die set]
The lower punch 4 has a top surface 41, an inner side surface 42i, an outer side surface 42o, an inner bottom surface 43i and an outer bottom surface 43o. Top surface 41 is elongated and flat with a curvature. The curved portion of the top surface 41 is a portion of the top surface 41 that curves within a flat plane. Note that the top surface 41 does not have to be a strictly flat surface. That is, the top surface 41 may have some unevenness. The shape of the top surface 41 reflects the shape of the top plate 102 of the press-formed product 101 . For example, when the top plate 102 of the press-formed product 101 is composed of a curved portion 121 and straight portions 122 connected to both ends of the curved portion 121, the top surface 41 includes the curved portion and both ends of the curved portion. Including a straight part leading to

The inner side surface 42 i connects to the curved inner side edge of the curved portion of the side edges of the top surface 41 . The shape of the inner side surface 42 i reflects the shape of the inner vertical wall 103 i of the press-formed product 101 . The outer side surface 42 o connects to the curved outer side edge of the curved portion of the both side edges of the top surface 41 . The shape of the outer side surface 42 o reflects the shape of the outer vertical wall 103 o of the press-formed product 101 . For example, when the inner vertical wall 103i of the press-formed product 101 is composed of a curved portion 131i and straight portions 132i connected to both ends of the curved portion 131i, the inner side surface 42i includes the curved portion and both ends of the curved portion. Including the straight part leading to each. When the outer vertical wall 103o of the press-formed product 101 is composed of a curved portion 131o and straight portions 132o connected to both ends of the curved portion 131o, the outer side surfaces 42o are formed at the curved portion and at both ends of the curved portion. Including connecting straight parts.

The inner bottom surface 43i connects to the lower edge of the inner side surface 42i. The shape of the inner bottom surface 43 i reflects the shape of the inner flange 104 i of the press-formed product 101 . The outer bottom surface 43o connects to the lower edge of the outer side surface 42o. The shape of the outer bottom surface 43 o reflects the shape of the outer flange 104 o of the press-formed product 101 . For example, when the inner flange 104i of the press-formed product 101 is composed of a curved portion 141i and straight portions 142i connected to both ends of the curved portion 141i, the inner bottom surface 43i includes the curved portion and both ends of the curved portion. Including a straight part leading to When the outer flange 104o of the press-formed product 101 is composed of a curved portion 141o and straight portions 142o connected to both ends of the curved portion 141o, the outer bottom surface 43o connects to the curved portion and both ends of the curved portion. Including straight part.

The lower cushion 5 supports the lower punch 4 via cushion pins 51 . A lower cushion 5 is fixed to the bed 2 . The lower cushion 5 is, for example, a hydraulic cylinder. The lower cushion 5 supports the lower punch 4 in a floating state with a high load. When a load greater than that applied to the lower punch 4 from the lower cushion 5 is applied to the lower punch 4 from above, the lower punch 4 can move downward.

The inner lower jig 6i is arranged adjacent to the inner bottom surface 43i of the lower punch 4 . The inner lower jig 6 i is fixed to the bed 2 . 6 and 7, the inner lower jig 6i is fixed to the lower die holder 10. As shown in FIGS. The inner lower jig 6i has an inner lower blade 61i on its edge adjacent to the inner bottom surface 43i of the lower punch 4. As shown in FIG.

The inner lower jig 6i has an inner groove 62i on its upper surface. The inner groove 62 i is formed along the curved inner side edge of the curved portion of the top surface 41 . From another point of view, the inner groove 62 i is formed parallel to the curved inner side edge of the curved portion of the top surface 41 . The term “parallel” here means not only complete parallelism, but also allows a slight deviation from perfect parallelism. In other words, the inner groove 62i is curved in plan view in the same manner as the curved portion of the top surface 41 . If the top surface 41 includes a curved portion and straight portions connecting to both ends of the curved portion, the inner groove 62i extends to a region of the top surface 41 corresponding to the straight portion. The cross-sectional shape of the inner groove 62i is trapezoidal. The trapezoid here means a trapezoid in which the inner groove 62i does not have a negative angle during press molding. That is, when the inner groove 62i is viewed in cross section, the width of the upper side is wider than the width of the bottom side. However, the cross-sectional shape of the inner groove 62i is not limited to a trapezoid, and may be rectangular, semicircular, or the like. Also, in order to prevent cracking, appropriate fillets R may be provided at the corners of the trapezoid, rectangle, and semicircle. Furthermore, the depth of the inner groove 62i must be such that it does not interfere with the inner ridge 85i at the bottom dead center of press forming. In a typical example, the depth of the inner groove 62i is greater than the height of the inner ridge 85i.

The height position of the upper surface of the inner lower jig 6i matches the initial height position of the inner bottom surface 43i of the lower punch 4. FIG. However, the height position of the upper surface of the inner lower jig 6i may be slightly lower than the initial height position of the inner bottom surface 43i of the lower punch 4. FIG.

The outer lower jig 6 o is arranged adjacent to the outer bottom surface 43 o of the lower punch 4 . The outer lower jig 6 o is fixed to the bed 2 . 6 and 7, the outer lower jig 6o is fixed to the lower mold holder 10. As shown in FIG. The outer lower jig 6o has an outer lower blade 61o on its edge adjacent to the outer bottom surface 43o of the lower punch 4. As shown in FIG.

The outer lower jig 6o has an outer groove 62o on its upper surface. The outer groove 62 o is formed along the curved outer side edge of the curved portion of the top surface 41 . From another point of view, the outer groove 62 o is formed parallel to the curved outer side edge of the curved portion of the top surface 41 . The term “parallel” here means not only complete parallelism, but also allows a slight deviation from perfect parallelism. That is, the outer groove 62o is curved in plan view in the same manner as the curved portion of the top surface 41 is. When the top surface 41 includes a curved portion and straight portions connected to both ends of the curved portion, the outer groove 62o extends to a region of the top surface 41 corresponding to the straight portion. The cross-sectional shape of the outer groove 62o is trapezoidal. The trapezoid here means a trapezoid in which the outer groove 62o does not have a negative angle during press molding. That is, when the outer groove 62o is viewed in cross section, the width of the upper side is wider than the width of the bottom side. However, the cross-sectional shape of the outer groove 62o is not limited to a trapezoid, and may be rectangular, semicircular, or the like. Also, in order to prevent cracking, appropriate fillets R may be provided at the corners of the trapezoid, rectangle, and semicircle. Furthermore, the depth of the outer groove 62o must be such that it does not interfere with the outer ridges 85o at the bottom dead center of press forming. In a typical example, the depth of the outer groove 62o is greater than the height of the outer ridge 85o.

The height position of the upper surface of the outer lower jig 6 o matches the initial height position of the outer bottom surface 43 o of the lower punch 4 . However, the height position of the upper surface of the outer lower jig 6o may be slightly lower than the initial height position of the outer bottom surface 43o of the lower punch 4. FIG.

In the press machine 1 shown in FIGS. 6 and 7, a bottoming member is provided between the lower punch 4 and the lower mold holder 10. As shown in FIG. The bottoming member comprises an upper plate 12 with a bottom attached to the lower surface of the lower punch 4 and a lower plate 13 with a bottom attached to the upper surface of the lower mold holder 10 . The upper plate 12 with a bottom faces the lower plate 13 with a bottom. When the lower surface of the upper plate 12 with the bottom comes into contact with the upper surface of the lower plate 13 with the bottom, the downward movement of the lower punch 4 is restricted.

[Upper die set]
The upper pad 7 is arranged to face the top surface 41 of the lower punch 4 . The shape of the lower surface of the upper pad 7 reflects the shape of the top plate 102 of the press-molded product 101 . The upper pad 7 is supported by the slide 3 via elastic members 71 . In addition, in the press apparatus 1 shown in FIGS. 6 and 7 , the elastic member 71 is fixed to the upper die holder 11 .

The elastic member 71 is, for example, a spring and a gas cylinder. When a load is applied to the upper pad 7 from below, the upper pad 7 can move upward with respect to the upper die 8 by contracting the elastic member 71 . After the blank 201 is sandwiched between the lower punch 4 and the upper die 8 to form the inner vertical wall 103i, the outer vertical wall 103o, the inner bottom surface 43i, and the outer bottom surface 43o, the inner upper blade 84i and the inner lower blade 61i, or In order to cut the blank 201 with the outer upper blade 84o and the outer lower blade 61o, the lower punch 4 must not move downward only by the load of the upper pad 7 via the elastic member 71. For this purpose, the elastic member 71 needs to support the upper pad 7 with a smaller load than the lower cushion 5 .

An upper die 8 is fixed to the slide 3 . 6 and 7, the upper die 8 is fixed to the upper die holder 11. As shown in FIGS. The upper die 8 has an inner wall surface 81i, an outer wall surface 81o, an inner lower surface 82i, an outer lower surface 82o, an inner recess 83i, and an outer recess 83o.

The inner wall surface 81 i corresponds to the inner side surface 42 i of the lower punch 4 . The shape of the inner wall surface 81 i reflects the shape of the inner vertical wall 103 i of the press-formed product 101 . The outer wall surface 81 o corresponds to the outer side surface 42 o of the lower punch 4 . The shape of the outer bottom surface 43 o reflects the shape of the outer vertical wall 103 o of the press-formed product 101 .

The inner bottom surface 82i faces the inner bottom surface 43i of the lower punch 4 . The shape of the inner lower surface 82 i reflects the shape of the inner flange 104 i of the press-formed product 101 . The outer bottom surface 82 o faces the outer bottom surface 43 o of the lower punch 4 . The shape of the outer lower surface 82 o reflects the shape of the outer flange 104 o of the press-formed product 101 .

The inner recess 83i adjoins the inner lower surface 82i. The inner recess 83i is arranged above the inner lower jig 6i. The outer recess 83o adjoins the outer lower surface 82o. The outer concave portion 83o is arranged above the outer lower jig 6o.

A boundary portion between the inner wall surface 81i and the inner lower surface 82i is an inner die shoulder 86i. A boundary portion between the outer wall surface 81o and the outer lower surface 82o is an outer die shoulder 86o.

The upper die 8 also has an inner upper blade 84i on the edge of the inner lower surface 82i adjacent to the inner recess 83i. The inner upper blade 84i is paired with the inner lower blade 61i of the inner lower jig 6i.

Furthermore, the upper die 8 has an inner ridge 85i at a position facing the inner groove 62i in the inner recess 83i. The inner ridge 85i protrudes from the inner lower surface 82i. That is, the inner ridge 85i protrudes downward. The inner ridge 85i makes a pair with the inner groove 62i of the inner lower jig 6i. Therefore, the inner ridges 85i are curved in plan view in the same manner as the inner grooves 62i. When the top surface 41 includes a curved portion and straight portions connected to both ends of the curved portion, the inner ridge 85i extends to a region of the top surface 41 corresponding to the straight portion. The cross-sectional shape of the inner ridge 85i is trapezoidal corresponding to the cross-sectional shape of the inner groove 62i. However, the cross-sectional shape of the inner ridge 85i may be rectangular, semicircular, or the like as long as it corresponds to the cross-sectional shape of the inner groove 62i. Also, in order to prevent cracking, appropriate fillets R may be provided at the corners of the trapezoid, rectangle, and semicircle.

The initial height position of the lower surface of the inner ridge 85i is preferably the same as the initial height position of the lower surface of the upper pad 7 or higher than the initial height position of the lower surface of the upper pad 7 . This is to prevent the inner ridge 85i from coming into contact with the blank 201 before pressing the top surface 41 with the upper pad 7 . If the inner ridge 85i contacts the blank 201 before the upper pad 7 presses the top surface 41, the blank 201 moves in the width direction of the product, making it difficult to obtain a product of a predetermined size. Also, if the initial height position of the lower surface of the inner ridge 85i is much higher than the initial height position of the lower surface of the upper pad 7, the elastic member 71 connected to the upper pad 7 must be long. Mold cost increases. Therefore, it is desirable that the initial height position of the lower surface of the inner ridge 85i is higher than the initial height position of the lower surface of the upper pad 7 by 20 mm at maximum. However, the initial height position of the lower surface of the upper pad 7 is lower than the initial height position of the inner lower surface 82 i of the upper die 8 .

The upper die 8 also has an outer upper blade 84o on the edge of the outer lower surface 82o adjacent to the outer concave portion 83o. The outer upper blade 84o is paired with the outer lower blade 61o of the outer lower jig 6o.

Furthermore, the upper die 8 has an outer protrusion 85o at a position facing the outer groove 62o in the outer recess 83o. The outer ridge 85o protrudes from the outer lower surface 82o. That is, the outer ridge 85o protrudes downward. The outer ridge 85o is paired with the outer groove 62o of the outer lower jig 6o. Therefore, the outer ridges 85o are curved in plan view in the same manner as the outer grooves 62o. When the top surface 41 includes a curved portion and straight portions connected to both ends of the curved portion, the outer ridge 85o extends to a region of the top surface 41 corresponding to the straight portion. The cross-sectional shape of the outer ridge 85o is trapezoidal corresponding to the cross-sectional shape of the outer groove 62o. However, the cross-sectional shape of the outer ridge 85o may be rectangular, semi-circular, or the like as long as it corresponds to the cross-sectional shape of the outer groove 62o. Also, in order to prevent cracking, appropriate fillets R may be provided at the corners of the trapezoid, rectangle, and semicircle.

The initial height position of the lower surface of the outer ridge 85o is preferably the same as the initial height position of the lower surface of the upper pad 7 or higher than the initial height position of the lower surface of the upper pad 7 . This is to prevent the outer ridges 85 o from contacting the blank 201 before pressing the top surface 41 with the upper pad 7 . If the outer ridge 85o contacts the blank 201 before pressing the top surface 41 with the upper pad 7, the blank 201 moves in the width direction of the product, making it difficult to obtain a product of predetermined dimensions. Further, if the initial height position of the lower surface of the outer ridge 85o is much higher than the initial height position of the lower surface of the upper pad 7, the elastic member 71 connected to the upper pad 7 must be long. Mold cost increases. Therefore, it is desirable that the initial height position of the lower surface of the outer ridge 85o is higher than the initial height position of the lower surface of the upper pad 7 by 20 mm at maximum. However, the initial height position of the lower surface of the upper pad 7 is lower than the initial height position of the outer lower surface 82 o of the upper die 8 .

[Manufacturing method of press-molded product 101]
A method for manufacturing the press-formed product 101 according to the present embodiment is a method for manufacturing the press-formed product 101 shown in FIGS. 1A and 1B using the press apparatus 1 shown in FIGS. The method for manufacturing the press-formed product 101 according to the present embodiment includes steps (a) to (e). Each step will be described below with reference to FIGS. 8A to 8F, 9 and 10. FIG.

8A to 8F are diagrams for explaining a method of manufacturing a press-formed product 101 using the press apparatus 1 of the first embodiment. The manufacturing steps proceed in the order shown in FIGS. 8A-8F. 8A to 8F show cross sections at positions where the curved portion of the press-formed product 101 is formed.

FIG. 9 is a plan view showing a blank 201 applied to the method of manufacturing the press-formed product 101 using the press apparatus 1 of the first embodiment. In FIG. 9, the blank 201 is indicated by a solid line, and the press-formed product 101 molded from this blank 201 is indicated by a two-dot chain line. FIG. 9 shows imaginary lines (in FIG. indicated by a thin double-dashed line (not attached). Also, in FIG. 9, the area where the inner grooves 62i and the inner ridges 85i of the press device 1 are installed and the area where the outer grooves 62o and the outer ridges 85o are installed are indicated by dotted lines.

FIG. 10 is a plan view for explaining the situation when the press-formed product 101 is formed by the manufacturing method using the press apparatus 1 of the first embodiment. In FIG. 10, a blank 201 is indicated by a solid line, and a press-formed product 101 molded from this blank 201 is indicated by a two-dot chain line. In addition, in FIG. 10, the tension applied to the inner vertical wall 103i, the inner flange 104i, the outer vertical wall 103o, and the outer flange 104o of the press-formed product 101 is indicated by dotted arrows. The longitudinal stress (component force) applied to each region is indicated by solid arrows.

[Step (a)]
8A and 9, first, in step (a), a blank 201 made of a metal plate is prepared. The blank 201 has a high strength (tensile strength) of, for example, 590 MPa or more. The thickness of the blank 201 is approximately 0.8 to 2.3 mm. A metal plate used for the blank 201 is, for example, a steel plate. A blank 201 having a predetermined shape is obtained by subjecting the metal plate to punching, cutting, machining, laser trimming, electrical discharge machining, or the like.

Here, in the press machine 1 of the present embodiment, as described above, the inner groove 62i and the inner ridge 85i are provided in the area further inside the curved portion of the press-formed product 101 . Further, the inner grooves 62i and the inner ridges 85i are also provided in the curved inner regions of the straight portions respectively connected to both ends of the curved portion of the press-formed product 101 . In other words, the inner grooves 62i and the inner ridges 85i are provided throughout the press-formed product 101 in the longitudinal direction.

In addition, in the press machine 1 of the present embodiment, the outer grooves 62o and the outer ridges 85o are provided in the region of the curved portion of the press-formed product 101 further outward of the curve, as described above. Further, the outer grooves 62o and the outer ridges 85o are also provided in the curved outer regions of the straight portions connected to both ends of the curved portion of the press-formed product 101 respectively. That is, the outer grooves 62o and the outer ridges 85o are provided over the entire length of the press-formed product 101. As shown in FIG.

The blank 201 has a size exceeding the area where the inner ridges 85i (inner grooves 62i) are arranged (installation area of the inner ridges 85i), and the outer ridges 85o (outer grooves 62o) are arranged. It has a size exceeding the area where the outer ridge 85o is located (the installation area of the outer ridge 85o). In other words, the inner edge 203i of the blank 201 exceeds the setting area of the inner ridge 85i (inner groove 62i). The outer edge 203o of the blank 201 extends beyond the installation area of the outer ridge 85o (outer groove 62o).

From another point of view, the width of the blank 201 is larger than the width of the press-formed product 101 when it is developed on the same plane. That is, the inner extra length portion 202i is provided on the curved inner side of the blank 201 . An outer extra length portion 202 o is provided on the curved outer side of the blank 201 . In the blank 201, the inner edge 203i of the inner extra length portion 202i exceeds the position of the side edge 106i of the inner flange 104i when the press-formed product 101 is developed on the same plane, and furthermore, the inner ridge 85i (inner groove 62i ) beyond the installation area. In the blank 201, the outer edge 203o of the outer extra length portion 202o exceeds the position of the side edge 106o of the outer flange 104o when the press-formed product 101 is developed on the same plane, and furthermore, the outer ridge 85o (outer beyond the installation area of the gutter 62o).

The installation area of the inner ridges 85i referred to here means the installation area of the inner ridges 85i in a state in which each molding surface of the upper die 8 is developed into a plane. In other words, the installation area of the inner groove 62i means the installation area of the inner groove 62i in a state in which the forming surfaces of the lower punch 4 and the inner lower jig 6i are developed flat. Further, the installation area of the outer ridges 85o referred to here means the installation area of the outer ridges 85o in a state in which each molding surface of the upper die 8 is developed into a plane. In other words, the installation area of the outer grooves 62o means an installation area of the outer grooves 62o in a state in which the forming surfaces of the lower punch 4 and the outer lower jig 6o are developed flat.

[Steps (b) and (c)]
In step (b), referring to FIG. 8A, blank 201 is placed on top surface 41 of lower punch 4 . After that, in step (c), the press device 1 is operated. That is, the slide 3 is lowered. Lowering the slide 3 lowers the upper pad 7 and the upper die 8 . Thereby, first, the blank 201 is sandwiched between the lower surface of the upper pad 7 and the top surface 41 of the lower punch 4 . That is, the upper pad 7 presses the area of the blank 201 that will become the top plate 102 (the curved portion 121 and the straight portion 122).

[Step (d)]
In step (d), the slide 3 is further lowered. Thereby, the blank 201 is pressed by the upper die 8 and the lower punch 4, the blank 201 is pressed by the inner ridges 85i and the inner grooves 62i, and the blank 201 is pressed by the outer ridges 85o and the outer grooves 62o. Further, during step (d), the lower punch 4 hardly moves downward and is supported by the lower cushion 5 via the cushion pin 51 . The area sandwiched between the lower punch 4 and the upper die 8 is formed with a force equal to or less than the load set by the lower cushion 5 .

Specifically, referring to FIG. 8B, the lowering of the slide 3 causes the upper die 8 to descend. At that time, while the upper pad 7 continues to press the blank 201, the elastic member 71 supporting the upper pad 7 contracts. As the upper die 8 descends, the inner die shoulder 86i of the upper die 8 comes into contact with the inner vertical wall 103i (curved portion 131i and straight portion 132i) of the blank 201, and the inner die shoulder 86i and the lower punch 4 are separated. The inner vertical wall 103i of the press-formed product 101 is gradually formed by the inner side surface 42i of the . At the same time, the outer die shoulder 86o of the upper die 8 comes into contact with the outer vertical wall 103o (the curved portion 131o and the straight portion 132o) of the blank 201, and the outer die shoulder 86o and the outer side surface of the lower punch 4 By 42o, the outer vertical wall 103o of the press-formed product 101 is gradually formed.

At that time, as shown in FIG. 8C, the inner vertical wall 103i and the outer vertical wall 103o are started to be formed, and the inner ridge 85i of the upper die 8 comes into contact with the blank 201, and the inner ridge 85i and the inner lower jig are brought into contact with each other. The inner groove 62i of 6i gradually shapes the inner valley 105i. At the same time, the outer ridges 85o of the upper die 8 come into contact with the blank 201, and the outer troughs 105o are gradually formed by the outer ridges 85o and the outer grooves 62o of the outer lower jig 6o.

When the forming of the inner valley 105i and the outer valley 105o begins, tension is generated in the area of the blank 201 between the inner die shoulder 86i and the inner ridge 85i (see dotted arrows in FIGS. 8C and 10). That is, in the blank 201, the drawing force toward the area to be the top plate 102 is resisted in the area to be the inner vertical wall 103i (curved portion 131i and straight portion 132i) and the inner flange 104i (curved portion 141i and straight portion 142i). Tension is applied. At the same time, tension in the transverse direction is generated in the blank 201 between the outer die shoulder 86o and the outer ridge 85o (see dotted arrows in FIGS. 8C and 10). In other words, in the blank 201, the drawing force toward the area to be the top plate 102 is resisted in the area to be the outer vertical wall 103o (curved portion 131o and straight portion 132o) and the outer flange 104o (curved portion 141o and straight portion 142o). Tension is applied.

In this case, referring to FIG. 10, it becomes a stretch-flange deformed portion, that is, a curved inner portion of the curved portion of the press-formed product 101 (a curved portion 131i of the inner vertical wall 103i and a curved portion 141i of the inner flange 104i). As for the region, a compressive stress is applied in the longitudinal direction as a force component in the longitudinal direction by applying tension (see the solid line arrow in FIG. 10).

Also, in this case, referring to FIG. 10, the portion that shrinks and is flange-deformed, that is, the portion outside the curve of the curved portion of the press-formed product 101 (the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o). In the region where the tension is applied, a tensile stress is applied in the longitudinal direction as a force component in the longitudinal direction (see solid line arrows in FIG. 10).

Then, as shown in FIG. 8D, each surface of the lower punch 4 (inner side surface 42i, outer side surface 42o, inner bottom surface 43i, and outer bottom surface 43o) and each surface of the upper die 8 (inner wall surface 81i, outer wall surface 81o, inner A press-formed product 101 is formed by the lower surface 82i and the outer lower surface 82o).

In this case, the inner curved portion of the curved portion of the press-formed product 101 (the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i) formed by stretch flange deformation is formed as described above. Since a longitudinal compressive stress is applied with the application of tension during the process of (1), the longitudinal tensile stress during press forming accompanying stretch flanging deformation is alleviated. Therefore, the tensile stress in the longitudinal direction can be reduced, and the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be reduced in the lateral direction.

Further, in this case, the curved outer portion of the curved portion of the press-formed product 101 (the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o) formed by shrinkage flange deformation is as described above. Since a tensile stress in the longitudinal direction is applied as tension is applied in the process of forming, the compressive stress in the longitudinal direction during press forming due to shrinkage flange deformation is relaxed. Therefore, the compressive stress in the longitudinal direction can be reduced, and the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be reduced in the transverse direction.

[Step (e)]
In step (e), the slide 3 is further lowered. Thereby, the blank 201 is cut by the inner upper blade 84i and the inner lower blade 61i, and the blank 201 is cut by the outer upper blade 84o and the outer lower blade 61o.

Specifically, referring to FIG. 8E, lowering the slide 3 lowers the upper die 8 . Along with this, the lower punch 4 supported by the lower cushion 5 descends. At that time, the press-formed product 101 descends together with the upper die 8 and the lower punch 4 while being held between the upper die 8 and the lower punch 4 .

Then, as shown in FIG. 8F, the inner upper blade 84i of the upper die 8 and the inner lower blade 61i of the inner lower jig 6i cut the boundary between the press-formed product 101 and the region including the inner valley portion 105i. This boundary is the curved inner side edge of the press-formed product 101, namely the side edge 106i of the inner flange 104i. As a result, the region including the inner valley portion 105i is removed from the press-formed product 101 . At the same time, the outer upper blade 84o of the upper die 8 and the outer lower blade 61o of the outer lower jig 6o cut the boundary between the press-formed product 101 and the area including the outer valley portion 105o. This boundary is the curved outer side edge of the press-formed product 101, namely the side edge 106o of the outer flange 104o. As a result, the region including the outer valley portion 105o is removed from the press-formed product 101. As shown in FIG.

As shown in FIG. 8F, lowering of the lower punch 4 is restricted by the contact of the upper plate 12 with the bottom with the lower plate 13 with the bottom. That is, the bottom dead point of the lower punch 4 is when the upper plate 12 with the bottom contacts the lower plate 13 with the bottom. Until the upper plate 12 with the bottom contacts the lower plate 13 with the bottom, the press-formed product 101 in the area between the lower punch 4 and the upper die 8 is formed under the cushion load set by the lower cushion 5 or less. When the upper plate 12 with the bottom comes into contact with the lower plate 13 with the bottom, the press-formed product 101 can be pressed with the press load set by the press machine. Generally, the cushion load is lower than the press load, and the difference between the cushion load and the press load allows the upper die 8 to move slightly downward after the lower punch 4 reaches the bottom dead center. That is, the bottom dead center of the upper die 8 is slightly delayed from the bottom dead center of the lower punch 4 . By slightly lowering the upper die 8, the press-formed product 101 is strongly pressed, and the shape of the press-formed product 101 becomes a precise product shape.

According to the method for manufacturing the press-formed product 101 of the present embodiment, the inner curved portion of the curved portion of the press-formed product 101 formed by stretch flange deformation (the curved portion 131i of the inner vertical wall 103i and the inner flange 104i Regarding the curved portion 141i), as described above, the tensile stress in the longitudinal direction during press molding can be reduced, and in the lateral direction, the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be reduced. For this reason, the compressive stress in the longitudinal direction due to springback can be reduced in the curved inner portion of the curved portion of the press-formed product 101 taken out from the mold, and in the lateral direction, the compressive stress on the outer surface and the tensile stress on the inner surface can be reduced. can reduce the difference between As a result, twisting and wall warping of the press-formed product 101 can be effectively suppressed.

In addition, according to the method for manufacturing the press-formed product 101 of the present embodiment, the curved outer portion of the curved portion of the press-formed product 101 (the curved portion 131o of the outer vertical wall 103o and the outer flange) formed by shrinkage flange deformation. As described above, the curved portion 141o) of 104o can reduce the compressive stress in the longitudinal direction during press molding, and can reduce the difference between the tensile stress on the outer surface and the compressive stress on the inner surface in the transverse direction. Therefore, in the curved outer portion of the curved portion of the press-formed product 101 taken out from the mold, the tensile stress in the longitudinal direction due to springback can be reduced, and in the lateral direction, the compressive stress on the outer surface and the tensile stress on the inner surface can be reduced. can reduce the difference between As a result, twisting and wall warping of the press-formed product 101 can be effectively suppressed.

In particular, according to the method of manufacturing the press-formed product 101 of the present embodiment, the stress in the longitudinal direction can be reduced in both the inner and outer curved portions of the curved portion of the press-formed product 101 . Therefore, twisting and wall warping of the press-formed product 101 can be suppressed more effectively.

Further, when the boundary between the press-formed product 101 and the region including the inner valley portion 105i is cut by the inner upper blade 84i and the inner lower blade 61i in step (e), the inner ridge 85i of the upper die 8 and the inner lower Forming of the inner valley portion 105i by the inner groove 62i of the jig 6i continues. This is because the upper die 8 is lowered with respect to the inner lower jig 6i. For this reason, the application of tension also continues. In a state in which tension is applied, if the inner upper blade 84i and the inner lower blade 61i slightly bite into the press-formed product 101, the press-formed product 101 is easily broken. Then, cutting can be easily performed. In general, after the lower blade or upper blade bites into the press-formed product, the amount of work hardening on the cut end face is smaller and the end face quality is better if the cut end face breaks easily than if it does not break easily. . Therefore, when the curved inner side edge (the side edge 106i of the inner flange 104i) of the press-formed product 101 is cut, the side edge has good properties. Moreover, since it is easily broken, damage to each of the inner upper blade 84i and the inner lower blade 61i is small.

From the same point of view, when the boundary between the press-formed product 101 and the region including the outer valley portion 105o is cut by the outer upper blade 84o and the outer lower blade 61o in step (e), the outer convex portion of the upper die 8 Forming of the outer valley portion 105o by the ridge 85o and the outer groove 62o of the outer lower jig 6o continues. This is because the upper die 8 is lowered with respect to the outer lower jig 6o. For this reason, the application of tension also continues. When the outer upper blade 84o and the outer lower blade 61o bite into the press-formed product 101 slightly under tension, the press-formed product 101 is easily broken. Then, cutting can be easily performed. Therefore, when the curved outer side edge (the side edge 106o of the outer flange 104o) of the press-formed product 101 is cut, the side edge has good properties. Moreover, since it is easily broken, damage to each of the outer upper blade 84o and the outer lower blade 61o is small.

[Second embodiment]
A press apparatus 1 of the second embodiment and a method for manufacturing a press-formed product 101 will be described below with reference to FIGS. 11 and 12 . The second embodiment is a modification of the first embodiment described above.

FIG. 11 is a cross-sectional view showing an example of the press device 1 of the second embodiment. A press machine 1 shown in FIG. 11 is used for manufacturing a press-formed product 101 shown in FIGS. 1A and 1B. FIG. 11 shows a cross section of the press-formed product 101 at the position where the curved portion is formed. The right side of FIG. 11 corresponds to the curved inner side of the curved portion of the press-formed product 101 , and the left side of FIG. 6 corresponds to the curved outer side of the curved portion of the press-formed product 101 .

FIG. 12 is a plan view showing a blank 201 applied to a method of manufacturing a press-formed product 101 using the press apparatus 1 of the second embodiment. In FIG. 12, the blank 201 is indicated by a solid line, and the press-formed product 101 molded from this blank 201 is indicated by a two-dot chain line. In FIG. 12, both side edges (the side edge 106i of the inner flange 104i and the side edge 106o of the outer flange 104o) when the press-formed product 101 to be molded is developed on the same plane are shown by imaginary lines (in FIG. indicated by a thin double-dashed line (not attached). Also, in FIG. 12, the installation areas of the inner grooves 62i and the inner ridges 85i of the press device 1 are indicated by dotted lines.

Referring to FIG. 11, the press apparatus 1 of this embodiment includes a bed 2, a slide 3, a lower punch 4, a lower cushion 5, an inner lower jig 6i, an upper pad 7 and an upper die 8. , provided. That is, the press device 1 of this embodiment does not include the outer lower jig 6o. Therefore, there is no outer lower cutting edge 61o and outer groove 62o as in the first embodiment. Further, the upper die 8 of the present embodiment does not have the outer concave portion 83o, the outer concave portion 83o, and the outer ridge 85o of the first embodiment. Other configurations are the same as those of the press device 1 of the first embodiment.

A method for manufacturing the press-formed product 101 according to the present embodiment is a method for manufacturing the press-formed product 101 shown in FIGS. 1A and 1B using the press apparatus 1 shown in FIG. The method of manufacturing the press-formed product 101 according to the present embodiment includes steps (a) to (e) as in the first embodiment.

Referring to FIG. 12, the blank 201 prepared in step (a) has a size exceeding the setting area of the inner ridge 85i (inner groove 62i), as in the first embodiment. From another point of view, an inner extra length portion 202i is provided on the curved inner side of the blank 201 . That is, as in the first embodiment, the inner edge 203i of the blank 201 exceeds the position of the side edge 106i of the inner flange 104i when the press-formed product 101 is developed on the same plane, and furthermore, the inner ridge 85i ( Beyond the installation area of the inner groove 62i). On the other hand, the outer extra length portion 202o is not provided on the curved outer side of the blank 201 . That is, the outer edge 203o of the blank 201 corresponds to the side edge 106o of the outer flange 104o when the press-formed product 101 is developed on the same plane.

In this case, in step (d), similarly to the first embodiment, the blank 201 is press-molded by the upper die 8 and the lower punch 4, and the blank 201 is press-molded by the inner ridge 85i and the inner groove 62i. Then, in step (e), the blank 201 is cut by the inner upper blade 84i and the inner lower blade 61i as in the first embodiment. For this reason, the stretch-flange deformed portion, that is, the inner curved portion of the curved portion of the press-formed product 101 (the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i) is subjected to tension during the molding process. Since the compressive stress in the longitudinal direction is applied along with the application, the tensile stress in the longitudinal direction during press forming due to stretch flanging deformation is alleviated. By doing so, the tensile stress in the longitudinal direction can be reduced, and the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be reduced in the transverse direction.

On the other hand, for the portion that shrinks and flanges are deformed, that is, the outer curved portion of the curved portion of the press-formed product 101 (the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o), the tension due to the formation of the valley portion No grant. This is because there are no outer ridges 85o and outer grooves 62o as in the first embodiment.

In the case of the second embodiment, reduction of the stress in the longitudinal direction and the lateral direction cannot be expected in the curved outer portion of the curved portion of the press-formed product 101 taken out from the mold. However, as in the first embodiment, the compressive stress in the longitudinal direction due to springback can be reduced in the curved inner portion of the curved portion of the press-molded product 101 removed from the mold, and the outer surface can be compressed in the lateral direction. The difference between the stress and the tensile stress on the inner surface can be reduced. As a result, twisting and wall warping of the press-formed product 101 can be effectively suppressed.

In addition, according to the manufacturing method using the press apparatus 1 of the second embodiment, it is also possible to manufacture the press-formed product 101 without the outer flange 104o. In this case, the outer edge 203o of the blank 201 to be prepared should correspond to the curved outer side edge (lower edge of the outer vertical wall 103o) when the press-formed product 101 to be molded is developed on the same plane. .

[Modification of Second Embodiment]
The press apparatus 1 of the second embodiment and the method of manufacturing the press-formed product 101 shown in FIGS. 11 and 12 can be modified as follows.

A press apparatus 1 of a modification of the second embodiment includes a bed 2, a slide 3, a lower punch 4, a lower cushion 5, an outer lower jig 6o, an upper pad 7, and an upper die 8. . That is, the press device 1 of the modified example of the second embodiment does not include the inner lower jig 6i. Therefore, the inner lower cutting edge 61i and the inner groove 62i as in the first embodiment do not exist. Further, the upper die 8 of the modified example of the second embodiment does not have the inner recessed portion 83i, the inner recessed portion 83i, and the inner ridge 85i as in the first embodiment. Other configurations are the same as those of the press device 1 of the first embodiment.

In the method of manufacturing the press-formed product 101 according to the modified example of the second embodiment, the blank 201 prepared in step (a) exceeds the setting area of the outer ridge 85o (outer groove 62o), as in the first embodiment. have a size. From another point of view, an outer extra length portion 202o is provided on the curved outer side of the blank 201 . That is, as in the first embodiment, the outer edge 203o of the blank 201 exceeds the position of the side edge 106o of the outer flange 104o when the press-formed product 101 is developed on the same plane, and furthermore, the outer ridge 85o ( beyond the installation area of the outer groove 62o). On the other hand, the inner surplus portion 202i is not provided on the curved inner side of the blank 201 . That is, the inner edge 203i of the blank 201 corresponds to the side edge 106i of the inner flange 104i when the press-formed product 101 is developed on the same plane.

In this case, in step (d), similarly to the first embodiment, the blank 201 is press-molded by the upper die 8 and the lower punch 4, and the blank 201 is press-molded by the outer ridge 85o and the outer groove 62o. Then, in step (e), the blank 201 is cut by the outer upper blade 84o and the outer lower blade 61o, as in the first embodiment. For this reason, the portions that undergo shrinkage flange deformation, that is, the outer curved portions of the curved portion of the press-formed product 101 (the curved portion 131o of the outer vertical wall 103o and the curved portion 141o of the outer flange 104o) are subjected to tension during the molding process. Since a tensile stress in the longitudinal direction is applied along with the application, the compressive stress in the longitudinal direction during press forming due to shrinkage flange deformation is alleviated. By doing so, the compressive stress in the longitudinal direction can be reduced, and the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be reduced in the transverse direction.

On the other hand, the portion that undergoes stretch flange deformation, that is, the inner portion of the curved portion of the press-formed product 101 (the curved portion 131i of the inner vertical wall 103i and the curved portion 141i of the inner flange 104i) is affected by the tension associated with the formation of the troughs. No grant. This is because there are no inner ridges 85i and inner grooves 62i as in the first embodiment.

In the case of the modified example of the second embodiment, reduction of the stress in the longitudinal direction and the lateral direction cannot be expected in the curved inner portion of the curved portion of the press-formed product 101 taken out from the mold. However, as in the first embodiment, the tensile stress in the longitudinal direction due to springback can be reduced in the curved outer portion of the curved portion of the press-formed product 101 taken out from the mold, and the outer surface can be compressed in the lateral direction. The difference between the stress and the tensile stress on the inner surface can be reduced. As a result, twisting and wall warping of the press-formed product 101 can be effectively suppressed.

In addition, according to the manufacturing method using the press apparatus 1 of the modified example of the second embodiment, it is also possible to manufacture the press-formed product 101 without the inner flange 104i. In this case, the inner edge 203i of the blank 201 to be prepared should correspond to the curved inner side edge (lower edge of the inner vertical wall 103i) when the press-formed product 101 to be molded is unfolded.

Other modifications and preferred embodiments will be described below.

[Inner Extra Length 202i and Outer Extra Length 202o of Blank 201]
As described above, in the present embodiment, when the press-formed product 101 is formed and the inner valley portion 105i is formed, the inner surplus portion 202i is provided on the curved inner side of the blank 201 . Further, when forming the outer trough portion 105o together with the forming of the press-formed product 101, an outer extra length portion 202o is provided on the curved outer side of the blank 201. As shown in FIG. Hereinafter, with reference to FIGS. 13 and 14, respective preferable ranges of the total width Wi of the inner extra length portion 202i and the total width Wo of the outer extra length portion 202o will be described.

FIG. 13 is a plan view of the blank 201. FIG. In FIG. 13, the blank 201 is indicated by a solid line, and the press-formed product 101 molded from this blank 201 is indicated by a two-dot chain line. In FIG. 13, both side edges (the side edge 106i of the inner flange 104i and the side edge 106o of the outer flange 104o) when the press-formed product 101 to be molded is developed on the same plane are shown by imaginary lines (in FIG. indicated by a thin double-dashed line (not attached). Also, in FIG. 13, the installation area of the inner groove 62i and the inner ridge 85i of the press device 1 and the installation area of the outer groove 62o and the outer ridge 85o are indicated by dotted lines.

FIG. 14 is a cross-sectional view showing a state during press molding. FIG. 14 shows a cross section of the press-formed product 101 at the position where the curved portion is formed. Note that FIG. 14 corresponds to FIG. 8F described above.

Referring to FIG. 14, Wi1 is the line length in the cross section from the side edge 106i of the inner flange 104i of the press-formed product 101 to the curved inner side edge 151i of the inner valley portion 105i. Hereinafter, this line length Wi1 is also referred to as the inner first line length Wi1. Wi2 is the line length in the cross section from the curved inner side edge 151i of the inner valley portion 105i to the inner side edge 203i of the blank 201 . Hereinafter, this wire length Wi2 is also referred to as an inner second wire length Wi2. The total width (Wi1+Wi2) of the inner first line length Wi1 and the inner second line length Wi2 developed on the same plane corresponds to the total width Wi of the inner extra length portion 202i shown in FIG.

The greater the inner second wire length Wi2, the greater the tension applied along with the formation of the inner valley portion 105i. If the inner second wire length Wi2 is 20 mm or more, this tension can be sufficiently secured. Therefore, the lower limit of the inner second wire length Wi2 is preferably 20 mm. On the other hand, the upper limit of the inner second wire length Wi2 is not particularly limited. However, if the inner second wire length Wi2 is 200 mm or more, the increase in tension is saturated. Therefore, the preferable upper limit of the inner second wire length Wi2 is 200 mm.

Similarly, referring to FIG. 14, the line length within the cross section from the side edge 106o of the outer flange 104o of the press-formed product 101 to the curved outer side edge 151o of the outer valley portion 105o is Wo1. . Hereinafter, this wire length Wo1 is also referred to as the outer first wire length Wo1. Further, the line length in the cross section from the curved outer side edge 151o of the outer valley portion 105o to the outer edge 203o of the blank 201 is Wo2. Hereinafter, this wire length Wo2 is also referred to as the outer second wire length Wo2. The sum of the line lengths (Wo1+Wo2) obtained by developing the first outer line length Wo1 and the second outer line length Wo2 on the same plane corresponds to the total width Wo of the outer extra length portion 202o shown in FIG.

As the outer second wire length Wo2 increases, the tension applied along with the formation of the outer valley portion 105o increases. If the outer second wire length Wo2 is 20 mm or more, this tension can be sufficiently ensured. Therefore, the lower limit of the outer second wire length Wo2 is preferably 20 mm. On the other hand, the upper limit of the outer second wire length Wo2 is not particularly limited. However, when the outer second wire length Wo2 is 200 mm or more, the increase in tension is saturated. Therefore, the preferred upper limit of the outer second wire length Wo2 is 200 mm.

[Preferred shape 1 of blank 201]
As described above, in the present embodiment, by forming the inner valley portion 105i together with the forming of the press-formed product 101, the portion that undergoes stretch flanging deformation, that is, the inner portion of the curved portion of the press-formed product 101 (inner vertical wall 103i, and the curved portion 141i) of the inner flange 104i) are tensioned and longitudinally compressive stress is applied to this region. If the longitudinal compressive stress applied with the application of tension can be increased, the longitudinal tensile stress during press forming due to stretch flanging deformation can be more alleviated. In order to realize this, the shape of the curved inner side of the blank 201 may be changed.

Typically, in the blank 201, the first region corresponding to at least the central portion in the longitudinal direction of the curved portion of the installation region of the inner ridge 85i (inner groove 62i) is the installation region of the inner ridge 85i (inner groove 62i). , and outside from both ends of the first region are cut out. In this case, in the blank 201, the inner valley 105i is not formed in the area of the notch adjacent to the first area. Therefore, the direction of the tension applied during the molding process of the inner valley portion 105i is inclined from the lateral direction. The component force in the longitudinal direction of the tension inclined from the lateral direction becomes larger, and is applied as longitudinal compressive stress. As a result, the tensile stress in the longitudinal direction during press forming that accompanies stretch flanging deformation is more relaxed.

An example of a preferred shape 1 of the blank 201 will be described below with reference to FIGS. 15 and 16. FIG.

FIG. 15 is a plan view showing a preferred shape 1 of the blank 201. FIG. In FIG. 15, the blank 201 is indicated by a solid line, and the press-formed product 101 formed from this blank 201 is indicated by a two-dot chain line. In FIG. 15, both side edges (the side edge 106i of the inner flange 104i and the side edge 106o of the outer flange 104o) when the press-formed product 101 to be molded is developed on the same plane are shown by imaginary lines (in FIG. indicated by a thin double-dashed line (not attached). Also, in FIG. 15, the installation area of the inner grooves 62i and the inner ridges 85i of the press device 1 and the installation area of the outer grooves 62o and the outer ridges 85o are indicated by dotted lines.

FIG. 16 is a plan view for explaining the situation when the blank 201 shown in FIG. 15 is formed into the press-formed product 101 by the manufacturing method of this embodiment. In FIG. 16, the blank 201 is indicated by a solid line, and the press-formed product 101 formed from this blank 201 is indicated by a two-dot chain line. In addition, in FIG. 16, the tension applied to the regions that become the inner vertical wall 103i and the inner flange 104i of the press-formed product 101 is indicated by dotted arrows. Stresses (component forces) are indicated by solid arrows.

15 and 16 show an example of manufacturing a press-formed product 101 corresponding to FIG. Similar effects are obtained when a press-formed product having no straight portions on both sides of the curved portion 111 is produced, or when a press-formed product having a straight portion provided only on one side is produced.

Referring to FIG. 15 , inner extra length portion 202 i of blank 201 is provided in a part of the region corresponding to curved portion 111 of press-formed product 101 . In other words, the inner extra length portion 202 i of the blank 201 is not provided in the region corresponding to the straight portion 112 of the press-formed product 101 . The curved portion 111 of the press-formed product 101 includes the curved portion 121 of the top plate 102, the curved portion 131i of the inner vertical wall 103i, the curved portion 131o of the outer vertical wall 103o, the curved portion 141i of the inner flange 104i, and the outer flange 104o. curved portion 141o (see FIG. 1B). The straight portion 112 of the press-formed product 101 includes the straight portion 122 of the top plate 102, the straight portion 132i of the inner vertical wall 103i, the straight portion 132o of the outer vertical wall 103o, the straight portion 142i of the inner flange 104i, and the straight portion of the outer flange 104o. It consists of a portion 142o (see FIG. 1B).

From another point of view, the inner ridge 85i (inner groove 62i) of the press device 1 is installed inside the curve of the curved portion 111 of the press-formed product 101, and the blank 201 has the inner ridge 85i (inner groove 62i). ) is provided in an area corresponding to at least the central portion of the installation area. A region outside from both ends 202ip of the inner extra length portion 202i is cut out. In other words, the blank 201 has cutouts 204i outside both edges 202ie of the inner extra length portion 202i (first region). The notch 204i is formed so that the contour shape of the inner extra length portion 202i is gentle. Edges 202ie appear by notches 204i at both ends 202ip of the inner extra length portion 202i. In a typical example, the edge 202ie of the inner extra length portion 202i is straight in plan view. The edge 202ie is inclined with respect to the widthwise direction.

In this case, as shown in FIG. 16, in the blank 201, the inner valley 105i is not formed in the area of the notch 204i on the inner side of the curve during press molding. That is, the area of the notch 204i on the curved inner side provides no tension. Therefore, the direction of the tension applied during the molding process of the inner valley portion 105i is further inclined from the lateral direction. This is due to the concentration of tension in the vicinity of both edges 202ie of the inner extra length portion 202i. The component force in the longitudinal direction of the tension inclined from the lateral direction becomes larger, and is applied as longitudinal compressive stress. As a result, the tensile stress during longitudinal forming associated with stretch-flange deformation is more relaxed.

In order to effectively develop such an effect, when the blank 201 is viewed in plan, the angle γi between the tangent line Lfi at both ends 202ip of the inner edge 203i and the edge 202ie is 10° or more and 70° or less. Preferably. If the angle γi is greater than 70°, the deformation concentrates on the edge 202ie of the inner extra length portion 202i and the end 202ip of each inner extra length portion 202i, causing cracks. If the angle γi is less than 10°, the notch 204i cannot be located in the inner valley portion 105i, and the notch 204i may not be formed.

A curved portion 111 of the press-formed product 101 shown in FIG. 15 is composed of one circular arc. In this case, with respect to the angle θ1 [°] formed between the arc center line Lc and the bending portion end connection line Ld, the angle θ2 [°] formed between the arc center line Lc and the extra length portion end connection line Lei is given by the following: It is preferable to satisfy the relationship of formula (1). In this specification, the arc centerline Lc means a line connecting the center of the arc forming the curved portion 111 and the center of curvature of the arc. The bending portion end connecting line Ld means a line connecting the end of the bending portion 111 and the center of curvature of the arc forming the bending portion 111 . The surplus portion end connecting line Lei means a line connecting the end 202ip of the inner edge 203i and the center of curvature of the arc forming the curved portion 111 .
0.2≤θ2/θ1≤0.9 (1)

If θ2/θ1 satisfies the relationship of formula (1), the stretch-flange deformation portion, that is, the region inside the curve of the curved portion 111 of the press-formed product 101, the longitudinal direction applied along with the application of tension. The compressive stress in the direction can be effectively increased, and the tensile stress in the longitudinal direction during press forming due to stretch flanging deformation can be more alleviated. Therefore, the tensile stress in the longitudinal direction can be further reduced, and the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be further reduced in the lateral direction. In this case, the compressive stress in the longitudinal direction can be further reduced in the curved inner portion of the curved portion 111 of the press-formed product 101 taken out from the mold, and the compressive stress on the outer surface and the tensile stress on the inner surface can be reduced in the lateral direction. The difference can be further reduced. As a result, twisting and wall warping of the press-formed product 101 can be effectively suppressed.

FIG. 17 is a diagram showing the relationship between .theta.2/.theta.1 and the twist angle of the press-formed product 101. As shown in FIG. The twist angle shown in FIG. 17 means the angle [°] by which the press-formed product 101 is twisted from the design dimensions. For comparison, FIG. 17 shows the twist angle of the press-formed product 101 manufactured by general press working without forming the inner valley portion 105i and the outer valley portion 105o. As is clear from FIG. 17, when θ2/θ1 is in the range of 0.2 or more and 0.9 or less, that is, the range shown in formula (1), the twist angle of the press-formed product 101 is extremely small.

[Preferred shape 2 of blank 201]
An example of a preferred shape 2 of the blank 201 will be described below with reference to FIG.

FIG. 18 is a plan view showing a preferred shape 2 of the blank 201. FIG. In FIG. 18, the blank 201 is indicated by a solid line, and the press-formed product 101 molded from this blank 201 is indicated by a two-dot chain line. In FIG. 18, both side edges (the side edge 106i of the inner flange 104i and the side edge 106o of the outer flange 104o) when the press-formed product 101 to be molded is developed on the same plane are shown by imaginary lines (in FIG. indicated by a thin double-dashed line (not attached). Also, in FIG. 18, the installation area of the inner grooves 62i and the inner ridges 85i of the press device 1 and the installation area of the outer grooves 62o and the outer ridges 85o are indicated by dotted lines.

The curved portion 111 of the press-formed product 101 shown in FIG. 18 is composed of two circular arcs and has the same shape as in FIG. 2B. One arc having a smaller radius of curvature Ra is also called a first arc, and the other arc having a larger curvature radius Rb than the first arc is also called a second arc. The first arc joins the second arc.

In this case, with respect to the angle θa1 [°] formed between the first arc center line Lc1 and the first curved portion end connecting line Ld1, the angle formed between the first arc center line Lc1 and the first extra length portion end connecting line Lei1 is θa2[°] preferably satisfies the relationship of the following formula (2). In this specification, the first circular arc center line Lc1 means a line connecting the center of the first circular arc forming the curved portion 111 and the center of curvature of the first circular arc. The first curved portion end connecting line Ld1 means a line connecting the end of the curved portion 111 on the first arc side and the center of curvature of the first arc. The first extra long portion end connecting line Lei1 means a line connecting one end 202ip of the inner extra long portion 202i and the center of curvature of the first circular arc.
0.2≤θa2/θa1≤0.9 (2)

Further, the angle θb2 formed between the second arc center line Lc2 and the second marginal portion end connecting line Lei2 is relative to the angle θb1 [°] formed between the second arc center line Lc2 and the second bending portion end connecting line Ld2. [°] preferably satisfies the relationship of the following formula (3). In this specification, the second arc centerline Lc2 means a line connecting the center of the second arc forming the curved portion 111 and the center of curvature of the second arc. The second curved portion end connecting line Ld2 means a line that connects the end of the curved portion 111 on the side of the second arc and the center of curvature of the second arc. The second marginal portion end connecting line Lei2 means a line connecting the other end 202ip of the inner marginal portion 202i and the center of curvature of the second circular arc.
0.2≤θb2/θb1≤0.9 (3)

When the curved portion 111 of the press-formed product 101 is composed of two arcs (a first arc and a second arc), θa2/θa1 satisfies the relationship of Equation (2), and θb2/θb1 satisfies the relationship of Equation (3). is satisfied, the same effect as when .theta.2/.theta.1 satisfies the relationship of formula (1) appears. However, another arc may be arranged between the first arc and the second arc. That is, the curved portion 111 of the press-formed product 101 may be composed of three or more arcs.

[Preferred shape 3 of blank 201]
As described above, in the present embodiment, by forming the outer valley portion 105o together with the molding of the press-formed product 101, the portion that shrinks and flanges are deformed, that is, the curved outer portion of the curved portion of the press-formed product 101 (outer vertical wall 103o and the curved portion 141o) of the outer flange 104o) are tensioned and longitudinally tensile stressed. If the tensile stress in the longitudinal direction that is applied along with the application of tension can be increased, it will be possible to further alleviate the compressive stress in the longitudinal direction that accompanies shrinkage flange deformation during press forming. To achieve this, the shape of the curved outer side of the blank 201 may be changed.

Typically, in the blank 201, each second region corresponding to at least both ends of the installation region of the outer ridges 85o (outer grooves 62o) exceeds the installation region of the outer ridges 85o (outer grooves 62o). A part of the region inside the two regions is cut out. In this case, in the blank 201, the outer valley 105o is not formed in the area of the notch adjacent to the second area. Therefore, the direction of the tension applied during the molding process of the outer valley portion 105o is inclined from the lateral direction. The component force in the longitudinal direction of the tension inclined from the lateral direction becomes larger, and is applied as tensile stress in the longitudinal direction. As a result, the compressive stress in the longitudinal direction during press forming due to shrinkage flange deformation is further alleviated.

An example of the preferred shape 3 of the blank 201 will be described below with reference to FIGS. 19 and 20. FIG.

FIG. 19 is a plan view showing a preferred shape 3 of the blank 201. FIG. In FIG. 19, the blank 201 is indicated by a solid line, and the press-formed product 101 formed from this blank 201 is indicated by a two-dot chain line. In FIG. 19, both side edges (the side edge 106i of the inner flange 104i and the side edge 106o of the outer flange 104o) when the press-formed product 101 to be molded is developed on the same plane are shown by imaginary lines (in FIG. indicated by a thin double-dashed line (not attached). Also, in FIG. 19, the installation area of the inner grooves 62i and the inner ridges 85i of the press device 1 and the installation area of the outer grooves 62o and the outer ridges 85o are indicated by dotted lines.

FIG. 20 is a plan view for explaining the situation when the blank 201 shown in FIG. 19 is formed into the press-formed product 101 by the manufacturing method of this embodiment. In FIG. 20, a blank 201 is indicated by a solid line, and a press-formed product 101 formed from this blank 201 is indicated by a two-dot chain line. In addition, in FIG. 20, the tension applied to the regions to be the outer vertical wall 103o and the outer flange 104o of the press-formed product 101 is indicated by dotted arrows. Stresses (component forces) are indicated by solid arrows.

19 and 20 show an example of manufacturing a press-formed product 101 corresponding to FIG. Similar effects are obtained when a press-formed product having no straight portions on both sides of the curved portion 111 is produced, or when a press-formed product having a straight portion provided only on one side is produced.

Referring to FIG. 19 , outer extra length portions 202 o of blank 201 are provided in regions corresponding to straight portions 112 of press-formed product 101 . The extra outer length portion 202 o of the blank 201 is continuous with regions corresponding to both ends of the curved portion 111 of the press-formed product 101 . The curved portion 111 of the press-formed product 101 includes the curved portion 121 of the top plate 102, the curved portion 131i of the inner vertical wall 103i, the curved portion 131o of the outer vertical wall 103o, the curved portion 141i of the inner flange 104i, and the outer flange 104o. curved portion 141o (see FIG. 1B). The straight portion 112 of the press-formed product 101 includes the straight portion 122 of the top plate 102, the straight portion 132i of the inner vertical wall 103i, the straight portion 132o of the outer vertical wall 103o, the straight portion 142i of the inner flange 104i, and the straight portion of the outer flange 104o. It consists of a portion 142o (see FIG. 1B).

From another point of view, the outer ridge 85o (outer groove 62o) of the press device 1 is installed on the curved outer side of the curved portion 111 of the press-formed product 101, and the blank 201 has the outer ridge 85o (outer groove 62o). ) are provided in each region corresponding to at least both ends of the installation region. A region inside the ends 202op of each outer extra length portion 202o is notched. That is, the blank 201 has cutouts 204o on the inner sides of the edges 202oe of the outer extra length portions 202o (second regions). The notch 204o is formed so that the contour shape of each outer extra length portion 202o is gentle. Edges 202oe appear at ends 202op of each outer extra length portion 202o by notches 204o. In a typical example, the edge 202oe of the outer extra length portion 202o is straight in plan view. The edge 202oe is inclined with respect to the lateral direction.

In this case, as shown in FIG. 20, in the blank 201, part of the outer trough 105o is not formed in the area of the notch 204o on the curved outer side during press molding. That is, the area of the notch 204o on the curved outer side does not provide tension. Therefore, the direction of the tension applied during the molding process of the outer valley portion 105o is further inclined from the lateral direction. This is due to the concentration of tension in the vicinity of the edge 202oe of the outer extra length portion 202o. The component force in the longitudinal direction of the tension that is more inclined than the transverse direction becomes larger, and is applied as tensile stress in the longitudinal direction. As a result, compressive stresses during longitudinal forming associated with shrink flange deformation are more relaxed.

In order to effectively develop such an effect, when the blank 201 is viewed in plan, the angle γo between the tangent line Lfo at the end 202op of the outer edge 203o and the edge 202oe is 10° or more and 70° or less. Preferably. If the angle γo is greater than 70°, the deformation concentrates on the edge 202oe of the outer extra length portion 202o and the end 202op of each outer extra length portion 202o, causing cracks. If the angle γo is less than 10°, the notch 204o cannot be located in the outer valley 105o, and the notch 204o may not be formed.

A curved portion 111 of the press-formed product 101 shown in FIG. 19 is composed of one circular arc. In this case, with respect to the angle θ1 [°] formed between the arc center line Lc and the bending portion end connection line Ld, the angle θ3 [°] formed between the arc center line Lc and the extra length portion end connection line Leo is given by the following: It is preferable to satisfy the relationship of formula (4). In this specification, the surplus portion end connecting line Leo means a line connecting the end 202op of the edge 202oe and the center of curvature of the arc forming the curved portion 111 . The meanings of the arc center line Lc and the curved portion end connecting line Ld are as described above.
0.15≤θ3/θ1≤0.7 (4)

If θ3/θ1 satisfies the relationship of formula (4), the portion that undergoes contraction flange deformation, that is, the region that is the outer portion of the curve of the curved portion 111 of the press-formed product 101, is given along with the application of tension. The tensile stress in the direction can be effectively increased, and the compressive stress in the longitudinal direction during press forming associated with shrinkage flange deformation can be more relaxed. Therefore, the compressive stress in the longitudinal direction can be further reduced, and the difference between the tensile stress on the outer surface and the compressive stress on the inner surface can be further reduced in the lateral direction. In this case, the tensile stress in the longitudinal direction can be further reduced in the curved outer portion of the curved portion 111 of the press-formed product 101 taken out from the mold, and in the lateral direction, the compression stress on the outer surface and the tensile stress on the inner surface can be reduced. The difference can be further reduced. As a result, twisting and wall warping of the press-formed product 101 can be effectively suppressed.

FIG. 21 is a diagram showing the relationship between .theta.3/.theta.1 and the twist angle of the press-formed product 101. As shown in FIG. The twist angle shown in FIG. 21 means the angle [°] by which the press-formed product 101 is twisted from the design dimensions. For comparison, FIG. 21 shows the twist angle of the press-formed product 101 manufactured by general press working without forming the inner valley portion 105i and the outer valley portion 105o. As is clear from FIG. 21, when θ3/θ1 is in the range of 0.15 or more and 0.7 or less, that is, the range shown in formula (4), the twist angle of the press-formed product 101 is extremely small.

[Preferred shape 4 of blank 201]
It is also possible to combine the preferred shapes 1 and 2 of the blank 201 described above. FIG. 22 shows a plan view of a preferred shape 4 of blank 201 . In the blank 201 shown in FIG. 22, the situation on the inside of the curve is the same as for shape 1 shown in FIG. 15, and the situation on the outside of the curve is the same as for shape 3 shown in FIG. Therefore, the stress in the longitudinal direction can be reduced in both the inner curved portion and the outer curved portion of the curved portion of the press-formed product 101 . Therefore, the press-formed product 101 with better dimensional accuracy can be obtained than when the stress in the longitudinal direction is reduced only on the inner side of the curve or when the stress in the longitudinal direction is reduced only on the outer side of the curve.

[Dimensions of inner ridge 85i and outer ridge 85o]
FIG. 23 is a cross-sectional view for explaining preferred dimensions of each of the inner ridge 85i and the outer ridge 85o. FIG. 23 shows a cross section at the position where the curved portion of the press-formed product 101 is formed.

Referring to FIG. 23, in the upper die 8 of the press device 1 of the present embodiment, it is preferable that the protrusion amount hi1 of the inner ridge 85i from the inner lower surface 82i is 5 mm or more. Similarly, it is preferable that the protrusion amount ho1 of the outer protrusion 85o from the outer lower surface 82o is 5 mm or more.

As described above, in order to apply tension to the portion that is stretch-flange deformed, that is, the region that will be the inner portion of the curved portion of the press-formed product 101, the inner ridge 85i of the upper die 8 and the inner lower jig 6i An inner valley 105i is formed by the side groove 62i. If the projection amount hi1 of the inner ridges 85i is 5 mm or more, tension is effectively applied to the inner portion of the curved portion of the press-formed product 101 during the process of forming the inner valley portion 105i. be. The protrusion amount hi1 of the inner ridge 85i is more preferably 9 mm or more. The upper limit of the protrusion amount hi1 of the inner ridge 85i is not particularly limited. However, if the projection amount hi1 of the inner ridge 85i is 20 mm or more, the effect of suppressing twisting and wall warpage is saturated. Therefore, the preferable upper limit of the protrusion amount hi1 of the inner ridge 85i is 20 mm.

In addition, as described above, in order to apply tension to the portion that is deformed by contraction flange deformation, that is, the region that will be the curved outer portion of the curved portion of the press-formed product 101, the outer ridge 85o of the upper die 8 and the outer lower jig 6o are arranged. An outer valley portion 105o is formed by the outer groove 62o. If the protrusion amount ho1 of the outer ridge 85o is 5 mm or more, tension is effectively applied to the outer curved portion of the curved portion of the press-formed product 101 in the process of forming the outer valley portion 105o. be. The protrusion amount ho1 of the outer protrusion 85o is more preferably 9 mm or more. The upper limit of the protrusion amount ho1 of the outer protrusion 85o is not particularly limited. However, if the protrusion amount ho1 of the outer protrusion 85o is 20 mm or more, the effect of suppressing twisting and wall warping is saturated. Therefore, the preferable upper limit of the protrusion amount ho1 of the outer protrusion 85o is 20 mm.

Further, referring to FIG. 23, in the upper die 8 of the pressing device 1 of the present embodiment, the width wi1 of the inner ridge 85i is preferably 0.8 times or more the height hi2 of the inner ridge 85i. . Similarly, the width wo1 of the outer protrusion 85o is preferably 0.8 times or more the height ho2 of the outer protrusion 85o. In this specification, the width wi1 of the inner ridge 85i means the widthwise length of the inner ridge 85i on the bottom surface of the inner recess 83i. The width wo1 of the outer protrusion 85o means the widthwise length of the outer protrusion 85o on the bottom surface of the outer recess 83o. The height hi2 of the inner protrusion 85i means the length in the height direction from the bottom surface of the inner recess 83i to the lower end of the inner protrusion 85i. The height ho2 of the outer protrusion 85o means the length in the height direction from the bottom surface of the outer recess 83o to the lower end of the outer protrusion 85o.

If the width wi1 of the inner ridge 85i is 0.8 times or more the height hi2 of the inner ridge 85i, the strength of the inner ridge 85i itself can be sufficiently secured. In this case, deformation, chipping, and the like of the inner ridge 85i can be suppressed. The upper limit of the width wi1 of the inner ridge 85i is not particularly limited. However, if the width wi1 of the inner ridges 85i exceeds 2.0 times the height hi2 of the inner ridges 85i, the strength of the inner ridges 85i does not change and rather the material yield deteriorates. Therefore, it is preferable that the width wi1 of the inner ridge 85i is 2.0 times or less the height hi2 of the inner ridge 85i.

Moreover, if the width wo1 of the outer protrusion 85o is 0.8 times or more the height ho2 of the outer protrusion 85o, the strength of the outer protrusion 85o itself can be sufficiently secured. In this case, it is possible to suppress deformation, chipping, and the like of the outer protrusion 85o. The upper limit of the width wo1 of the outer protrusion 85o is not particularly limited. However, if the width wo1 of the outer ridges 85o exceeds 2.0 times the height ho2 of the outer ridges 85o, the strength of the outer ridges 85o does not change, and rather the material yield deteriorates. Therefore, it is preferable that the width wo1 of the outer protrusion 85o is 2.0 times or less the height ho2 of the outer protrusion 85o.

[Dimensions of inner lower jig 6i and outer lower jig 6o]
FIG. 24 is a cross-sectional view for explaining preferred dimensions of each of the inner lower jig 6i and the outer lower jig 6o. FIG. 24 shows a cross section at the position where the curved portion of the press-formed product 101 is formed.

Referring to FIG. 24, in the inner lower jig 6i of the press apparatus 1 of this embodiment, the edge adjacent to the inner bottom surface 43i of the lower punch 4 functions as an inner lower blade 61i. On the upper surface of the inner lower jig 6i, the smaller the distance wi2 from the edge adjacent to the inner bottom surface 43i of the lower punch 4 to the edge of the inner groove 62i on the lower punch 4 side, the higher the material yield of the blank 201 is. However, if the distance wi2 is too small, it becomes difficult to ensure the strength of the inner lower blade 61i. Therefore, the distance wi2 is preferably 20 mm or more and 100 mm or less.

Further, referring to FIG. 24, in the outer lower jig 6o of the press apparatus 1 of the present embodiment, the edge adjacent to the outer bottom surface 43o of the lower punch 4 functions as an outer lower blade 61o. On the upper surface of the outer lower jig 6o, the smaller the distance wo2 from the edge adjacent to the outer bottom surface 43o of the lower punch 4 to the edge of the outer groove 62o on the lower punch 4 side, the higher the material yield of the blank 201 is. However, if the distance wo2 is too small, it becomes difficult to ensure the strength of the outer lower blade 61o. Therefore, the distance wo2 is preferably 20 mm or more and 100 mm or less.

[Initial height positions of the inner bottom surface 43i and the outer bottom surface 43o of the lower punch 4]
FIG. 25 is a cross-sectional view for explaining preferred initial height positions of the inner bottom surface 43i and the outer bottom surface 43o of the lower punch 4. As shown in FIG. FIG. 25 shows a cross section at the position where the curved portion of the press-formed product 101 is formed.

Referring to FIG. 25, the initial height position of the inner bottom surface 43i of the lower punch 4 may be slightly higher than the height position of the upper surface of the inner lower jig 6i. That is, the relative height hi3 between the initial height position of the inner bottom surface 43i of the lower punch 4 and the initial height position of the inner bottom surface 43i of the lower punch 4 may be positive. When the relative height hi3 is negative, the blank 201 is pushed by the lower blade and the upper blade while the region sandwiched between the upper die 8 and the lower punch 4 is formed, that is, during the above step (d). This is because there is a possibility that biting cutting will start. By the way, when the relative height hi3 is positive, the press-formed product 101 is formed together with the upper die 8 and the lower punch 4 after the press-formed product 101 is formed by the surfaces of the lower punch 4 and the upper die 8. descend to Thereafter, cutting by the inner upper blade 84i and the inner lower blade 61i and cutting by the outer upper blade 84o and the outer lower blade 61o are performed. In other words, cutting is not performed immediately after the press-formed product 101 is formed by the surfaces of the lower punch 4 and the surfaces of the upper die 8 .

Even in such a case, the inner valley portion 105i continues to be formed by the inner ridge 85i of the upper die 8 and the inner groove 62i of the inner lower jig 6i until cutting is performed. This is because the upper die 8 is lowered with respect to the inner lower jig 6i. For this reason, the application of tension also continues. Therefore, longitudinal compressive stress can be applied along with application of tension to the portion that undergoes stretch flanging deformation, that is, the region that is the inner portion of the curved portion of the press-formed product 101 . Therefore, it is possible to reduce the tensile stress in the longitudinal direction during press forming due to stretch flanging deformation, and in the lateral direction, it is possible to reduce the difference between the tensile stress on the outer surface and the compressive stress on the inner surface. In this case, the compressive stress in the longitudinal direction can be reduced in the curved inner portion of the curved portion of the press-formed product 101 removed from the mold, and the difference between the compressive stress on the outer surface and the tensile stress on the inner surface can be reduced in the lateral direction. can be reduced. As a result, twisting and wall warpage of the press-formed product 101 can be suppressed.

However, the greater the relative height hi3, the smaller the tension. Therefore, it is preferable that the relative height hi3 is 3 mm or less. The most preferred relative height hi3 is 0 (zero) mm. In this case, the initial height position of the inner bottom surface 43i of the lower punch 4 matches the height position of the upper surface of the inner lower jig 6i.

Further, referring to FIG. 25, the initial height position of the outer bottom surface 43o of the lower punch 4 may be slightly higher than the height position of the upper surface of the outer lower jig 6o. That is, the relative height ho3 between the initial height position of the outer bottom surface 43o of the lower punch 4 and the initial height position of the outer bottom surface 43o of the lower punch 4 may be positive. In this case, after the press-formed product 101 is formed by the surfaces of the lower punch 4 and the surfaces of the upper die 8 , the press-formed product 101 descends together with the upper die 8 and the lower punch 4 . Thereafter, cutting by the outer upper blade 84o and the outer lower blade 61o and cutting by the outer upper blade 84o and the outer lower blade 61o are performed. In other words, cutting is not performed immediately after the press-formed product 101 is formed by the surfaces of the lower punch 4 and the surfaces of the upper die 8 .

Even in such a case, the formation of the outer troughs 105o by the outer ridges 85o of the upper die 8 and the outer grooves 62o of the outer lower jig 6o continues until cutting is performed. This is because the upper die 8 is lowered with respect to the outer lower jig 6o. For this reason, the application of tension also continues. Therefore, a longitudinal tensile stress can be applied along with the application of tension to the portion that undergoes contraction flange deformation, that is, the region that is the outer portion of the curve of the curved portion of the press-formed product 101 . Therefore, it is possible to reduce the compressive stress in the longitudinal direction during press forming due to shrinkage flange deformation, and in the lateral direction, it is possible to reduce the difference between the tensile stress on the outer surface and the compressive stress on the inner surface. In this case, the tensile stress in the longitudinal direction can be reduced in the curved outer portion of the curved portion of the press-formed product 101 removed from the mold, and the difference between the compressive stress on the outer surface and the tensile stress on the inner surface can be reduced in the lateral direction. can be reduced. As a result, twisting and wall warpage of the press-formed product 101 can be suppressed.

However, the greater the relative height ho3, the smaller the tension. Therefore, it is preferable that the relative height ho3 is 3 mm or less. The most preferred relative height ho3 is 0 (zero) mm. In this case, the initial height position of the outer bottom surface 43o of the lower punch 4 coincides with the height position of the upper surface of the outer lower jig 6o.

[Load applied from lower cushion 5 to lower punch 4]
An upward load is applied to the lower punch 4 by the lower cushion 5 . This load is called the cushion load F. After the region sandwiched between the upper die 8 and the lower punch 4 is formed, that is, after the step (d) described above is completed, in order to perform the cutting in the step (e) described above, each surface of the lower punch 4 It is necessary that the lower punch 4 does not descend until the press-formed product 101 is formed by the upper die 8 and each surface of the upper die 8 .

Therefore, it is desirable that the cushion load F satisfies the following formula (5).
F≧L×TS×t×0.2 (5)
The meaning of each symbol in formula (5) is as follows;
L: length in the longitudinal direction of the press-formed product 101 [mm],
TS: tensile strength [MPa] of blank 201, and t: plate thickness of blank 201 [mm].

[Descent amount of lower punch 4 and respective depths of inner recess 83i and outer recess 83o of upper die 8]
FIG. 26 is a cross-sectional view for explaining a suitable lowering amount of the lower punch 4 and suitable depths of the inner recess 83i and the outer recess 83o of the upper die 8, respectively. FIG. 26 shows a cross section at the position where the curved portion of the press-formed product 101 is formed.

Referring to FIG. 26, it is preferable that the lowering amount h4 of the lower punch 4 satisfies the following formula (6).
1.1×t≦h4≦9.0×t (6)
The meanings of the symbols in formula (6) are as follows;
t: plate thickness [mm] of the blank 201;

26, the amount of descent h4 of the lower punch 4 is the gap in the height direction between the upper plate 12 and the lower plate 13 with the bottom. The contact of the upper plate 12 with the bottom with the lower plate 13 with the bottom restricts the downward movement of the lower punch 4 .

As the lower punch 4 descends, the cutting of the blank 201 is performed by the outer upper blade 84o and the outer lower blade 61o. If the amount of descent h4 of the lower punch 4 is too small, cutting cannot be performed. Therefore, it is preferable that the amount of descent h4 of the lower punch 4 is 1.1 times or more the plate thickness t of the blank 201 . On the other hand, if the descending amount h4 of the lower punch 4 is too large, the height of the die becomes larger than necessary, and the material cost of the die also increases. Therefore, it is preferable that the descending amount h4 of the lower punch 4 is 9.0 times or less the plate thickness t of the blank 201 .

Further, referring to FIG. 26, the depth hi5 of the inner concave portion 83i of the upper die 8 is preferably larger than the lowering amount h4 of the lower punch 4. As shown in FIG. In this specification, the depth hi5 of the inner recess 83i means the length in the height direction from the inner lower surface 82i of the upper die 8 to the bottom surface of the inner recess 83i. If the depth hi5 of the inner concave portion 83i is larger than the lowering amount h4 of the lower punch 4, the lower punch 4 can surely reach the bottom dead center.

Further, referring to FIG. 26, the depth ho5 of the outer concave portion 83o of the upper die 8 is preferably larger than the lowering amount h4 of the lower punch 4. As shown in FIG. In this specification, the depth ho5 of the outer concave portion 83o means the length in the height direction from the outer lower surface 82o of the upper die 8 to the bottom surface of the outer concave portion 83o. If the depth ho5 of the outer concave portion 83o is greater than the lowering amount h4 of the lower punch 4, the lower punch 4 can reliably reach the bottom dead center.

[Shapes of inner lower cutting edge 61i and outer lower cutting edge 61o]
Preferred shapes of the inner lower cutting edge 61i and the outer lower cutting edge 61o will be described with reference to FIGS. 27A and 27B.

FIG. 27A is a diagram showing a preferred shape of the inner lower blade 61i. FIG. 27A shows a partial side surface of the inner lower jig 6i when viewed horizontally from the lower punch 4 side, which includes an inner lower blade 61i for cutting a region corresponding to the curved portion of the press-formed product 101. FIG. A side is shown. In addition, in FIG. 27A, the inner upper cutting edge 84i paired with the inner lower cutting edge 61i is indicated by an imaginary line (thin chain double-dashed line in FIG. 27A). The blank 201 is hatched in FIG. 27A.

Referring to FIG. 27A, the inner lower blade 61i is inclined such that the center Ric of the range corresponding to the curved inner side edge of the curved portion is lower than both ends Rie of the range. On the other hand, the inner upper blade 84i is straight with a constant height. The inner upper blade 84i of the upper die 8 descends and the blank 201 is cut by the inner upper blade 84i and the inner lower blade 61i.

When the region including the inner valley portion 105i is removed from the press-formed product 101 by the inner upper blade 84i and the inner lower blade 61i, the curved inner side edge of the press-formed product 101 may not be cut at the same time. Instead, it is gradually cut from each end of the side edge toward the center of the side edge. This is because the inner lower cutting edge 61i has the above-described shear angle βi. Therefore, the press load required for cutting can be small. Also, during cutting, a compressive stress is applied in the longitudinal direction. Therefore, tensile stress in the longitudinal direction during press molding is further relaxed. As a result, tensile stress in the longitudinal direction can be further reduced.

The shear angle βi is desirably 0.5° or more and 4.5° or less. If the shear angle βi is less than 0.5°, the effect of suppressing torsion and the effect of reducing the load are low, almost the same as when there is no shear angle. If the shear angle βi is greater than 4.5°, the molding stroke hzi until punching increases, resulting in a larger mold size and an increased mold cost.

FIG. 27B is a diagram showing a preferred shape of the outer lower blade 61o. FIG. 27B shows a partial side surface of the outer lower jig 6o when viewed horizontally from the lower punch 4 side, which includes an outer lower blade 61o for cutting a region corresponding to the curved portion of the press-formed product 101. A side is shown. In addition, in FIG. 27B, the outer upper blade 84o paired with the outer lower blade 61o is indicated by an imaginary line (thin chain double-dashed line in FIG. 27B). The blank 201 is hatched in FIG. 27B.

Referring to FIG. 27B, the outer lower blade 61o is inclined such that the center Roc of the range corresponding to the curved outer side edge of the curved portion is higher than both ends Roe of the range. On the other hand, the outer upper blade 84o is straight with a constant height. The outer upper blade 84o of the upper die 8 descends, and the blank 201 is cut by the outer upper blade 84o and the outer lower blade 61o.

When the region including the outer valley portion 105o is removed from the press-formed product 101 by the outer upper blade 84o and the outer lower blade 61o, the curved outer side edge of the curved portion of the press-formed product 101 may not be cut at the same time. Instead, it is gradually cut from the center of the side edge to each end of the side edge. This is because the outer lower cutting edge 61o has the above-described shear angle βo. Therefore, the press load required for cutting can be small. Also, a tensile stress is applied in the longitudinal direction during cutting. Therefore, the compressive stress in the longitudinal direction during press molding is more relaxed. As a result, compressive stress in the longitudinal direction can be further reduced.

The shear angle βo is desirably 0.5° or more and 4.5° or less. If the shear angle βo is less than 0.5°, the torsion suppressing effect and the load reducing effect are low, almost the same as when there is no shear angle. If the shear angle βo is greater than 4.5°, the molding stroke hzo until punching increases, resulting in a larger mold size and an increased mold cost.

CAE analysis was performed to confirm the effects of this embodiment. For CAE analysis, a commercially available general-purpose solver, LS-DYNAver. 971 was used. In the CAE analysis, models of the press-formed product 101 shown in FIGS. 1A and 1B were created under various conditions.

The main dimensions of the press-formed product 101 were as follows. These dimensions were reflected in various molds.
・The curvature radius of the curved inner side edge of the curved portion 121 of the top plate 102 in plan view: 1200 mm
・Width of top plate 102: 32 mm
・Radius of curvature in the cross section of the inner surface of the corner portion between the top plate 102 and the inner vertical wall 103i: 4.5 mm
・Radius of curvature in the cross section of the inner surface of the corner portion between the top plate 102 and the outer vertical wall 103o: 4.5 mm
・Height of inner vertical wall 103i: 40 mm
・Height of outer vertical wall 103o: 40mm
・Radius of curvature in the cross section of the inner surface of the corner portion between the inner vertical wall 103i and the inner flange 104i: 4.5 mm
・Radius of curvature in the cross section of the inner surface of the corner portion between the outer vertical wall 103o and the outer flange 104o: 4.5 mm
・Width of inner flange 104i: 18 mm
・Width of outer flange 104o: 18 mm

Molding analysis and springback analysis of the press-formed product 101 using various molds were performed. The torsion and wall warpage of the press-formed product 101 were evaluated from the results of the springback analysis. The evaluation method is shown in Figures 28A and 28B.

FIG. 28A is a perspective view for explaining a torsion evaluation method. FIG. 28A shows the press-formed product 101 after springback with a solid line. Also, in FIG. 28A, the press-formed product 101 before springback is indicated by a two-dot chain line.

The twist was evaluated by the twist angle [°]. Specifically, referring to FIG. 28A, one end edge of top plate 102 of press-formed product 101 after springback was aligned with one end edge of top plate 102 of press-formed product 101 before springback. Then, the angle α [°] at which the other edge of the top plate 102 of the press-formed product 101 after springback is twisted with respect to the other edge of the top plate 102 of the press-formed product 101 before springback is calculated, This was taken as the torsion angle. A smaller twist angle means a smaller twist of the press-formed product 101 .

FIG. 28B is a cross-sectional view for explaining a wall warpage evaluation method. FIG. 28B shows the press-formed product 101 after springback with a solid line. In addition, in FIG. 28B, the press-formed product 101 before springback is indicated by a two-dot chain line.

Wall warp was evaluated by wall warp curvature [/mm]. Specifically, referring to FIG. 28B, in the cross section of the center of the press-formed product 101 in the longitudinal direction, the top plate 102 of the press-formed product 101 after springback is attached to the top plate of the press-formed product 101 before springback. Aligned with plate 102 . Then, in the press-formed product 101 after springback, the average value of the curvature C of the lower end side of the inner vertical wall 103i and the curvature C of the lower end side of the outer vertical wall 103o was calculated, and this was taken as the wall warp curvature. A smaller wall warp curvature means a smaller wall warp.

The results are summarized in Table 1 below.

In a comparative example, a press-formed product 101 was formed by general press working. That is, in the comparative example, neither the inner valley portion 105i nor the outer valley portion 105o were formed.

In Example 1, both the inner valley portion 105i and the outer valley portion 105o were formed in the process of forming the press-formed product 101, and finally the region including the inner valley portion 105i and the outer valley portion 105o was cut. At the time of molding, in the blank 201, the total width Wi of the inner extra length portion 202i was set to 80 mm, and the total width Wo of the outer extra length portion 202o was set to 80 mm. The inner valley portion 105i has a height of 10 mm and a width of 20 mm. The outer valley portion 105o has a height of 10 mm and a width of 20 mm.

In Example 2, only the inner valley portion 105i was formed in the process of forming the press-formed product 101, and finally the region including the inner valley portion 105i was cut. At the time of molding, in the blank 201, the total width Wi of the inner extra length portion 202i was set to 80 mm. The inner valley portion 105i has a height of 10 mm and a width of 20 mm.

In Example 3, only the outer valley portion 105o was formed in the process of forming the press-formed product 101, and finally the region including the outer valley portion 105o was cut. At the time of molding, in the blank 201, the total width Wo of the outer extra length portion 202o was set to 80 mm. The outer valley portion 105o has a height of 10 mm and a width of 20 mm.

In Example 4, both the inner valley portion 105i and the outer valley portion 105o were formed in the process of forming the press-formed product 101, and finally the region including the inner valley portion 105i and the outer valley portion 105o was cut. At the time of molding, in the blank 201, the total width Wi of the inner extra length portion 202i was set to 80 mm, and the total width Wo of the outer extra length portion 202o was set to 80 mm. The inner valley portion 105i has a height of 2 mm and a width of 5 mm. That is, the cross-sectional size of the inner valley portion 105i of Example 4 was smaller than that of the inner valley portion 105i of Example 1. The outer valley portion 105o has a height of 2 mm and a width of 5 mm. That is, the lateral cross-sectional size of the outer valley portion 105o of Example 4 was smaller than that of the outer valley portion 105o of Example 1.

In Example 5, both the inner valley portion 105i and the outer valley portion 105o were formed in the process of forming the press-formed product 101, and finally the region including the inner valley portion 105i and the outer valley portion 105o was cut. At the time of molding, in the blank 201, the total width Wi of the inner extra length portion 202i was set to 80 mm, and the total width Wo of the outer extra length portion 202o was set to 80 mm. The inner valley portion 105i has a height of 10 mm and a width of 8 mm. That is, the width of the inner valley portion 105i of Example 5 was smaller than the width of the inner valley portion 105i of Example 1. The outer valley portion 105o has a height of 10 mm and a width of 8 mm. That is, the width of the outer valley portion 105o of Example 5 was smaller than the width of the outer valley portion 105o of Example 1.

In Example 6, only the inner valley portion 105i was formed in the process of forming the press-formed product 101, and finally the region including the inner valley portion 105i was cut. At the time of molding, in the blank 201, the total width Wi of the inner extra length portion 202i was set to 80 mm. The inner valley portion 105i has a height of 10 mm and a width of 8 mm. That is, the width of the inner valley portion 105i of Example 6 was smaller than the width of the inner valley portion 105i of Example 2.

In Example 7, only the outer valley portion 105o was formed in the process of forming the press-formed product 101, and finally the region including the outer valley portion 105o was cut. At the time of molding, in the blank 201, the total width Wo of the outer extra length portion 202o was set to 80 mm. The outer valley portion 105o has a height of 10 mm and a width of 8 mm. That is, the width of the outer valley portion 105o of Example 7 was smaller than the width of the outer valley portion 105o of Example 3.

In Example 8, both the inner valley portion 105i and the outer valley portion 105o were formed in the process of forming the press-formed product 101, and finally the region including the inner valley portion 105i and the outer valley portion 105o was cut. At the time of molding, in the blank 201, the total width Wi of the inner extra length portion 202i was set to 80 mm, and the total width Wo of the outer extra length portion 202o was set to 80 mm. The inner valley portion 105i has a height of 20 mm and a width of 30 mm. That is, the height of the inner valley portion 105i of Example 8 was greater than the height of the inner valley portion 105i of Example 1. The outer valley portion 105o has a height of 20 mm and a width of 30 mm. That is, the height of the outer valley portion 105o of Example 8 was greater than the height of the outer valley portion 105o of Example 1.

In Example 9, only the inner valley portion 105i was formed in the process of forming the press-formed product 101, and finally the region including the inner valley portion 105i was cut. At the time of molding, in the blank 201, the total width Wi of the inner extra length portion 202i was set to 80 mm. The inner valley portion 105i has a height of 20 mm and a width of 30 mm. That is, the height of the inner valley portion 105i of Example 9 was greater than that of the inner valley portion 105i of Example 2.

In Example 10, only the outer valley portion 105o was formed in the process of forming the press-formed product 101, and finally the region including the outer valley portion 105o was cut. At the time of molding, in the blank 201, the total width Wo of the outer extra length portion 202o was set to 80 mm. The outer valley portion 105o has a height of 20 mm and a width of 30 mm. That is, the height of the outer valley portion 105o of Example 10 was greater than the height of the outer valley portion 105o of Example 3.

In Example 11, both the inner valley portion 105i and the outer valley portion 105o were formed in the process of forming the press-formed product 101, and finally the region including the inner valley portion 105i and the outer valley portion 105o was cut. At the time of molding, in the blank 201, the total width Wi of the inner extra length portion 202i was set to 80 mm, and the total width Wo of the outer extra length portion 202o was set to 80 mm. The inner valley portion 105i has a height of 5 mm and a width of 7.5 mm. That is, the height of the inner valley portion 105i of Example 11 was smaller than that of the inner valley portion 105i of Example 1. The outer valley portion 105o has a height of 5 mm and a width of 7.5 mm. That is, the height of the outer valley portion 105o of Example 11 was smaller than the height of the outer valley portion 105o of Example 1.

In Example 12, only the inner valley portion 105i was formed in the process of forming the press-formed product 101, and finally the region including the inner valley portion 105i was cut. At the time of molding, in the blank 201, the total width Wi of the inner extra length portion 202i was set to 80 mm. The inner valley portion 105i has a height of 5 mm and a width of 7.5 mm. That is, the height of the inner valley portion 105i of Example 12 was smaller than that of the inner valley portion 105i of Example 2.

In Example 13, only the outer valley portion 105o was formed in the process of forming the press-formed product 101, and finally the region including the outer valley portion 105o was cut. At the time of molding, in the blank 201, the total width Wo of the outer extra length portion 202o was set to 80 mm. The outer valley portion 105o has a height of 5 mm and a width of 7.5 mm. That is, the height of the outer valley portion 105o of Example 13 was smaller than the height of the outer valley portion 105o of Example 3.

In the reference example, both the inner valley portion 105i and the outer valley portion 105o were formed in the process of forming the press-formed product 101 . At the time of molding, in the blank 201, the total width Wi of the inner extra length portion 202i was set to 80 mm, and the total width Wo of the outer extra length portion 202o was set to 80 mm. The inner valley portion 105i has a height of 10 mm and a width of 20 mm. The outer valley portion 105o has a height of 10 mm and a width of 20 mm. Unlike Example 1, the final cutting of the region including the inner valley portion 105i and the outer valley portion 105o was not performed.

The results in Table 1 show the following.

In Example 1, the twist angle was significantly smaller than that of the comparative example, and the wall warp curvature was significantly smaller than that of the comparative example. Thus, it was found that twisting and wall warping can be most effectively suppressed when both the inner valley portion 105i and the outer valley portion 105o are formed.

In Example 2, the twist angle was smaller than in Comparative Example, and the wall warp curvature was smaller than in Comparative Example, though not as much as in Example 1. As a result, it was found that when the inner valley portion 105i was formed, twisting and wall warping could be effectively suppressed.

In Example 3, the twist angle was smaller than in Comparative Example, though not as much as in Example 1. The wall warp curvature of Example 3 was smaller than that of Comparative Example. Thus, it was found that twisting and wall warpage can be effectively suppressed when the outer valley portion 105o is formed.

In Example 4, the twist angle was slightly smaller than in Comparative Example. The wall warp curvature of Example 4 was slightly smaller than that of Comparative Example. As a result, it has been found that when the inner valley portion 105i and the outer valley portion 105o to be molded are small in size, twisting and wall warpage can be suppressed to some extent.

In Example 5, as in Example 1, the twist angle was significantly smaller than that of the comparative example, and the wall warp curvature was significantly smaller than that of the comparative example. As a result, it was found that twisting and wall warping can be effectively suppressed by molding both the inner valley portion 105i and the outer valley portion 105o, and if the width of each valley portion is 0.8 times or more of its height.

In Example 6, the twist angle was smaller than that of Comparative Example, and the wall warp curvature was smaller than that of Comparative Example, though not as much as in Example 5. From this, it was found that twisting and wall warping can be effectively suppressed if the inner valley portion 105i is formed and the width of the valley portion is 0.8 times or more the height of the valley portion.

In Example 7, the twist angle was smaller than in the comparative example, and the wall warp curvature was smaller than in the comparative example, though not as much as in the example 5. As a result, it was found that twisting and wall warping can be effectively suppressed if the outer valley portion 105o is formed and the width of the valley portion is at least 0.8 times its height.

In Example 8, the twist angle was significantly smaller than that of the comparative example, and the wall warp curvature was significantly smaller than that of the comparative example. In addition, since the twist angle and the wall warp curvature were smaller than in Example 1, in which the height of the valley was lower than in Example 8, it was found that the higher the height of the valley, the greater the effect. From this, it was found that twisting and wall warping can be most effectively suppressed when both the inner valley portion 105i and the outer valley portion 105o, each having a height of 20 mm, are formed.

In Example 9, the twist angle was smaller than in Comparative Example, and the wall warp curvature was smaller than in Comparative Example, though not as much as in Example 8. In addition, since the twist angle and the wall warp curvature were smaller than in Example 2 in which the height of the valley was lower than in Example 9, it was found that the higher the height of the valley, the greater the effect. Thus, it was found that twisting and wall warpage can be effectively suppressed when the inner valley portion 105i having a height of 20 mm is formed.

In Example 10, the twist angle was smaller than in Comparative Example, and the wall warp curvature was smaller than in Comparative Example, though not as much as in Example 8. In addition, since the twist angle and the wall warp curvature were smaller than in Example 3, in which the height of the valley was lower than that of Example 10, it was found that the higher the height of the valley, the more effective it was. As a result, it was found that twisting and wall warpage can be effectively suppressed when the outer valley portion 105o having a height of 20 mm is formed.

In Example 11, the twist angle was smaller than the comparative example, and the wall warp curvature was smaller than the comparative example. In addition, the twist angle and the wall warp curvature were larger than in Example 1, which has a higher valley portion height than in Example 11. From this, it was found that the higher the height of the trough, the more effective it is, but if the height of the trough is 5 mm or more, it is possible to effectively suppress torsion and wall warpage.

In Example 12, the twist angle was smaller than the comparative example, and the wall warp curvature was smaller than the comparative example. Moreover, the twist angle and the wall warp curvature were larger than those of Example 2 in which the height of the valley portion was higher than that of Example 12. From this, it was found that the higher the height of the trough, the more effective it is, but if the height of the trough is 5 mm or more, it is possible to effectively suppress torsion and wall warping.

In Example 13, the twist angle was smaller than the comparative example, and the wall warp curvature was smaller than the comparative example. Moreover, the twist angle and the wall warp curvature were larger than those of Example 3 in which the height of the valley portion was higher than that of Example 13. From this, it was found that the higher the height of the trough, the more effective it is, but if the height of the trough is 5 mm or more, it is possible to effectively suppress torsion and wall warpage.

In the reference example, the twist angle was equivalent to that in the comparative example. The wall warp curvature of the reference example was equivalent to that of the comparative example. In other words, the torsion and wall warpage could not be suppressed unless the region including the inner valley portion 105i and the outer valley portion 105o was finally cut.

The embodiments of the present invention have been described above. However, the above-described embodiments are merely examples for implementing the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit of the present invention.

1 press device 2: bed 3: slide 4: lower punch 41: top surface 42i: inner side surface 42o: outer side surface 43i: inner bottom surface 43o: outer bottom surface 5: lower cushion 6i: inner lower jig 61i: inner lower blade 62i: Inner groove 6o: Outer lower jig 61o: Outer lower blade 62o: Outer groove 7: Upper pad 8: Upper die 84i: Inner upper blade 84o: Outer upper blade 85i: Inner ridge 85o: Outer ridge 101: Press molded product 111: curved portion 102: top plate 103i: inner vertical wall 103o: outer vertical wall 104i: inner flange 104o: outer flange 105i: inner valley 105o: outer valley 201: blank 202i: inner margin 202o: outer margin Part 203i: inner edge 203o: outer edge

Claims (15)

bed and
a slide that can move up and down with respect to the bed;
an elongated top surface having a curved portion that curves in-plane; an inner side surface of both side edges of the top surface that connects to a curved inner side edge of the curved portion; a lower punch having an outer side surface connected to the curved outer side edge, an inner bottom surface connected to the lower edge of the inner side surface, and an outer bottom surface connected to the lower edge of the outer side surface;
a lower cushion that supports the lower punch and is fixed to the bed;
An inner lower jig arranged adjacent to the inner bottom surface of the lower punch and fixed to the bed, wherein the edge of the upper surface of the inner lower jig adjacent to the inner bottom surface of the lower punch is the inner lower jig having an inner lower blade and an inner groove formed in the upper surface along the curved inner side edge of the curved portion;
an upper pad arranged to face the top surface of the lower punch and supported by the slide via an elastic member;
An upper die fixed to the slide, comprising an inner wall surface corresponding to the inner side surface of the lower punch, an outer wall surface corresponding to the outer side surface of the lower punch, and an inner lower surface facing the inner bottom surface of the lower punch. , an outer lower surface facing the outer bottom surface of the lower punch, and an inner recess adjacent to the inner lower surface, and an inner upper blade on an edge of the inner lower surface adjacent to the inner recess, the inner recess and the upper die having an inner ridge protruding from the inner lower surface at a position facing the inner groove in the bottom surface of the die. bed and
a slide that can move up and down with respect to the bed;
an elongated top surface having a curved portion that curves in-plane; an inner side surface of both side edges of the top surface that connects to a curved inner side edge of the curved portion; a lower punch having an outer side surface connected to the curved outer side edge, an inner bottom surface connected to the lower edge of the inner side surface, and an outer bottom surface connected to the lower edge of the outer side surface;
a lower cushion that supports the lower punch and is fixed to the bed;
An outer lower jig that is arranged adjacent to the outer bottom surface of the lower punch and fixed to the bed, wherein the edge of the upper surface of the outer lower jig that is adjacent to the outer bottom surface of the lower punch is provided. the outer lower jig having an outer lower blade and an outer groove formed on the upper surface along the curved outer side edge of the curved portion;
an upper pad arranged to face the top surface of the lower punch and supported by the slide via an elastic member;
An upper die fixed to the slide, comprising an inner wall surface corresponding to the inner side surface of the lower punch, an outer wall surface corresponding to the outer side surface of the lower punch, and an inner lower surface facing the inner bottom surface of the lower punch. , an outer lower surface facing the outer bottom surface of the lower punch, and an outer recess adjacent to the outer lower surface, and an outer upper blade on an edge of the outer lower surface adjacent to the outer recess, the outer recess the upper die having an outer ridge protruding from the outer lower surface at a position facing the outer groove in the bottom surface of the die. The press device according to claim 1,
The pressing device further includes an outer lower jig that is arranged adjacent to the outer bottom surface of the lower punch and is fixed to the bed, wherein the lower punch of the upper surface of the outer lower jig is arranged to be adjacent to the outer bottom surface of the lower punch. the outer lower jig having an outer lower blade on the edge adjacent to the outer bottom surface, and an outer groove formed on the upper surface along the curved outer side edge of the curved portion;
The upper die further has an outer recess adjacent to the outer lower surface, an outer upper blade on the edge of the outer lower surface adjacent to the outer recess, and a bottom surface of the outer recess corresponding to the outer groove. A press device having outer ridges at opposing positions that protrude from the outer lower surface. The press device according to claim 1 or 3,
The pressing device, wherein the protrusion amount of the inner protrusion from the inner lower surface is 5 mm or more. The press apparatus according to any one of claims 1, 3 and 4,
The press device, wherein the width of the inner ridge is 0.8 times or more the height of the inner ridge. The press device according to any one of claims 1, 3, 4 and 5,
In the press device, the inner lower blade is inclined in a longitudinal range corresponding to the curved inner side edge of the curved portion so that the center of the range is lower than both ends of the range. The press device according to claim 2 or 3,
The pressing device, wherein the protrusion amount of the outer protrusion from the outer lower surface is 5 mm or more. The press device according to any one of claims 2, 3 and 7,
The press device, wherein the width of the outer protrusion is 0.8 times or more the height of the outer protrusion. The press device according to any one of claims 2, 3, 7 and 8,
In the press device, the outer lower blade is inclined in a longitudinal range corresponding to the curved outer side edge of the curved portion so that the center of the range is higher than both ends of the range. Using the press apparatus according to any one of claims 1, 3, 4, 5 and 6, an elongated top plate having a curved portion that curves in the plane, and the curved portion of the both side edges of the top plate an inner vertical wall connected to the curved inner side edge, an outer vertical wall connected to the curved outer side edge of the curved portion of both side edges of the top plate, an inner flange connected to the lower edge of the inner vertical wall, and A method for manufacturing a press-formed product including an outer flange connected to the lower edge of the outer vertical wall,
The manufacturing method is
(a) a step of preparing a blank made of a metal plate having a size exceeding the setting area of the inner ridge of the upper die;
(b) placing the blank on the top surface of the lower punch;
(c) lowering the slide to sandwich the blank between the upper pad and the top surface of the lower punch;
(d) further lowering the slide to press the blank with the upper die and the lower punch, and press the blank with the inner ridge and the inner groove;
(e) A method of manufacturing a press-formed product, comprising the step of further lowering the slide and cutting the blank with the inner upper blade and the inner lower blade. Using the press apparatus according to any one of claims 2, 3, 7, 8 and 9, an elongated top plate having a curved portion that curves in the plane, and the curved portion of the both side edges of the top plate an inner vertical wall connected to the curved inner side edge, an outer vertical wall connected to the curved outer side edge of the curved portion of both side edges of the top plate, an inner flange connected to the lower edge of the inner vertical wall, and A method for manufacturing a press-formed product including an outer flange connected to the lower edge of the outer vertical wall,
The manufacturing method is
(a) a step of preparing a blank made of a metal plate having a size exceeding the setting area of the outer ridges of the upper die;
(b) placing the blank on the top surface of the lower punch;
(c) lowering the slide to sandwich the blank between the upper pad and the top surface of the lower punch;
(d) further lowering the slide to press the blank with the upper die and the lower punch, and press the blank with the outer ridge and the outer groove;
(e) A method of manufacturing a press-formed product, comprising the step of further lowering the slide and cutting the blank with the outer upper blade and the outer lower blade. Using the press device according to claim 3 and any one of claims 4 to 9 citing claim 3, an elongated top plate having a curved portion that curves in the plane, and both side edges of the top plate an inner vertical wall connected to the curved inner side edge of the curved portion of the top plate, an outer vertical wall connected to the curved outer side edge of the curved portion among both side edges of the top plate, and the lower edge of the inner vertical wall A method for manufacturing a press-formed product including an inner flange that connects and an outer flange that connects to the lower edge of the outer vertical wall,
The manufacturing method is
(a) preparing a blank made of a metal plate having a size that exceeds the installation area of the inner ridges of the upper die and exceeds the installation area of the outer ridges of the upper die;
(b) placing the blank on the top surface of the lower punch;
(c) lowering the slide to sandwich the blank between the upper pad and the top surface of the lower punch;
(d) further descending the slide to press the blank with the upper die and the lower punch, press the blank with the inner ridge and the inner groove, and press the outer ridge and the outer groove; pressing the blank by
(e) further lowering the slide to cut the blank with the inner upper blade and the inner lower blade, and cutting the blank with the outer upper blade and the outer lower blade; A method of manufacturing molded articles. A method for manufacturing a press-formed product according to claim 10 or 12,
In the blank prepared in the step (a), a first region corresponding to at least a central portion in the longitudinal direction of the installation region of the inner ridge of the upper die exceeds the installation region of the inner ridge, and the A method for manufacturing a press-formed product, wherein regions outside from both ends of the first region are notched. A method for manufacturing a press-formed product according to claim 11 or 12,
In the blank prepared in the step (a), second regions corresponding to at least longitudinal ends of the installation regions of the outer ridges of the upper die exceed the installation regions of the outer ridges, A method for manufacturing a press-formed product, wherein the regions inside the second regions are notched. A method for manufacturing a press-formed product according to claim 12,
In the blank prepared in the step (a), a first region corresponding to at least a central portion in the longitudinal direction of the installation region of the inner ridge of the upper die exceeds the installation region of the inner ridge, Regions outside from both ends of one region are notched, and second regions corresponding to at least both ends in the longitudinal direction of the installation region of the outer ridges of the upper die are the installation of the outer ridges. A method for manufacturing a press-formed product, wherein a region extending beyond the region and inside the second regions is notched.

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