WO2023153285A1 - Press-forming apparatus and method for producing press-formed article - Google Patents

Abstract

This press forming apparatus comprises a punch, a die, and a blank holder. The punch has a top surface, a side surface, and a punch shoulder located between the top surface and the side surface. The punch shoulder has a punch shoulder straight section extending with a radius of curvature of greater than or equal to 500 mm and a punch shoulder curved section extending with a radius of curvature of less than 500 mm. An area of the top surface located adjacent to the punch shoulder curved section convexly extends outward from the top surface. The top surface has a protrusion protruding in the pressing direction. The protrusion extends along the extending direction in which the punch shoulder straight section extends. The bottom of a die hole in the die has a shape corresponding to the top surface. The blank holder is disposed opposite the plate pressing surface of the die.

Description

PRESS MOLDING APPARATUS AND METHOD OF MANUFACTURING PRESS MOLDED PRODUCT

The present invention relates to a press-molding apparatus and a method of manufacturing a press-molded product.
This application claims priority based on Japanese Patent Application No. 2022-019563 filed in Japan on February 10, 2022, the contents of which are incorporated herein.

Conventionally, there has been a press forming apparatus that forms a formed product of a desired shape by drawing forming in which the end portion of a high-strength, thin-walled material is sandwiched between a die and a punch and pressed (for example, See Patent Document 1).

Japanese Patent No. 2560416

However, draw forming with conventional press forming equipment may cause defects such as wrinkles and cracks in the vicinity of the curved portion of the molded product.

An object of the present invention is to provide a press-molding apparatus and a method of manufacturing a press-molded product that can suppress defects occurring in the curved portion of the molded product in view of the problems of the background art described above.

In order to solve the above problems, the present invention proposes the following means.
(1) Aspect 1 of the present invention comprises a punch, a die, and a blank holder, the punch having a top surface, side surfaces, and a punch shoulder disposed between the top surface and the side surfaces; wherein the punch shoulder includes a punch shoulder straight portion extending with a radius of curvature of 500 mm or more and a curved punch shoulder portion extending with a radius of curvature of less than 500 mm, and the punch shoulder curved portion on the top surface The adjacent portions protrude toward the outside of the top surface, and the top surface has a protrusion projecting in the pressing direction, and the protrusion extends in the extending direction of the straight punch shoulder portion. , the bottom surface of the die hole of the die has a shape corresponding to the top surface, and the blank holder is arranged to face the plate holding surface of the die. .

(2) In a second aspect of the present invention, when viewed from the pressing direction, the distance in the extension direction between the tip of the protrusion in the extension direction and the center of the punch shoulder straight portion is equal to the punch shoulder straight portion. 40% or more of the length in the extending direction of the press forming apparatus according to (1).
(3) A third aspect of the present invention is characterized in that, when viewed from the pressing direction, a first straight line passing between the punch shoulder straight portion and the punch shoulder curved portion and perpendicular to the extending direction and a straight line between the punch shoulder curved portion and the punch shoulder curved portion. The press molding apparatus according to (1) or (2) may be provided, wherein the tip portion of the convex portion is between a second straight line passing through the center portion and parallel to the first straight line.

(4) In a fourth aspect of the present invention, in a cross section passing through the protrusion and perpendicular to the extending direction, the length of the surface of the protrusion is 1.5 times the width of the protrusion perpendicular to the pressing direction. The press molding apparatus according to any one of (1) to (3) may be more than twice.
(5) In a fifth aspect of the present invention, in cross sections along the pressing direction and the extending direction through the convex portion, the surface of the tip portion of the convex portion in the extending direction and the pressing direction form The press molding apparatus according to any one of (1) to (4) may be used, wherein the angle is 30° or more.

(6) According to mode 6 of the present invention, when viewed from the pressing direction, the centroid of the top surface is inside the top of 20% or more of the height of the protrusion in the pressing direction, from (1) The press molding apparatus according to any one of (5) may be used.
(7) A seventh aspect of the present invention is the press according to any one of (1) to (6), wherein the angle formed by the two punch shoulder straight portions on both sides of the punch shoulder curved portion is an acute angle. It may be a molding device.

(8) Aspect 8 of the present invention is a method for manufacturing a press-formed product using the press-forming apparatus according to any one of (1) to (7), wherein a metal plate is formed with the die and the blank holder. and draw-forming the metal plate with the press-forming device, wherein the metal plate has a tensile strength of 980 MPa or more.

(9) A ninth aspect of the present invention may be the method for manufacturing a press-formed product according to (8), wherein the portion formed on the metal plate is removed by the protrusion.

According to the press molding apparatus and the method for manufacturing a press-molded product of the present invention, it is possible to suppress defects that occur in the curved portion of the molded product.

1 is a perspective view of a press-formed product manufactured by a press-forming apparatus according to one embodiment of the present invention; FIG. It is a top view of the same press-molded product. It is a perspective view of the annular component manufactured from the same press-molded product. It is the perspective view which decomposed|disassembled the same press molding apparatus. It is sectional drawing of the same press forming apparatus before draw-forming a metal plate. It is a top view of the punch of the same press molding apparatus. FIG. 7 is a cross-sectional view taken along a cutting line A1-A1 in FIG. 6; 7 is a cross-sectional view taken along a cutting line A2-A2 in FIG. 6; FIG. It is a flow chart which shows a manufacturing method of a press-formed article in one embodiment of the present invention. It is sectional drawing of the same press forming apparatus in the middle of draw-forming a metal plate. It is a cross-sectional view of the same press forming apparatus after drawing the metal plate. FIG. 10 is a plan view showing the inflow state of the metal plate in the main part of the press-formed product of the comparative example; FIG. 4 is a plan view showing a state in which a metal plate is introduced into a main portion of the press-formed product; FIG. 4 is a diagram showing changes in plate thickness reduction rate ratios with respect to values of (De/Ds). FIG. 4 is a diagram showing changes in thickness reduction rate ratio with respect to line length ratio (Lp/Ls). It is a figure which shows the change of thickness reduction rate ratio with respect to the depth Hp. It is a top view of the press-formed article of the 1st modification of one Embodiment. FIG. 10 is a diagram showing changes in the plate thickness reduction rate ratio with respect to the value of (De/Ds) for the press-formed product of the first modified example. It is a perspective view of the press-formed product of the 2nd modification of one Embodiment. FIG. 11 is a perspective view of a press-formed product of a third modified example of one embodiment; It is a perspective view of the press-formed product of the 4th modification of one Embodiment. It is a perspective view of the annular component of the 1st modification of one Embodiment. FIG. 11 is a perspective view of an annular component of a second modification of one embodiment; FIG. 11 is a perspective view of an annular component of a third modified example of one embodiment;

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a press-molding apparatus and a method of manufacturing a press-molded product according to the present invention will be described below with reference to FIGS. 1 to 24. FIG.
First, an annular component manufactured by a press molding apparatus and a method for manufacturing a press-molded product, and a press-molded product that is an intermediate molded product formed during the manufacture of the annular component will be described below.

[Press molded product]
As shown in FIGS. 1 and 2, for example, a press-formed product 100A includes a top plate 10, a peripheral wall 20, and a flange 30. As shown in FIGS. The press-formed product 100A has a deep dish shape.
The top plate 10 presents a polygonal shape with rounded corners when viewed in the thickness direction of the top plate 10 . In this example, the top plate 10 has a rectangular shape with rounded corners, which is obtained by rounding the corners of a rectangular shape having long sides and short sides. That is, between two rounded corners there is either a long side or a short side.
A projection 11 is formed on the top plate 10 . In this example, the top plate 10 is formed with two protrusions 11 . Each protruding portion 11 protrudes in the thickness direction (protruding direction) D1 on the first surface 10a side of the top plate 10 . Here, the surface of the top plate 10 opposite to the first surface 10a is referred to as a second surface 10b. That is, the deep dish-shaped outer surface of the top plate 10 is the first surface 10a, and the deep dish-shaped inner surface of the top plate 10 is the second surface 10b.
Each projecting portion 11 is a groove that extends (extends) in the direction along the long side when viewed from the second surface 10b of the top plate 10 . The two projecting portions 11 are spaced apart from each other in the direction along the short side of the top plate 10 . The two projecting portions 11 are arranged in the middle portion of the top plate 10 when viewed in the thickness direction of the top plate 10 . That is, a flat surface is formed by the second surface 10b between each protrusion 11 and the edge of the second surface 10b.

The peripheral wall 20 protrudes from the edge of the top plate 10 in the anti-protrusion direction D2 opposite to the protruding direction D1. The peripheral wall 20 is formed along the entire edge of the top plate 10 . The angle formed by the second surface 10b of the top plate 10 and the peripheral wall 20 may be an obtuse angle or a right angle.
The flange 30 protrudes outward from the peripheral wall 20 from the end of the peripheral wall 20 in the anti-projection direction D2. The flange 30 is formed over the entire circumference of the peripheral wall 20 .

The shape of the press-formed product 100A is not limited to this. For example, the press-formed product 100A may not have the flange 30.

[Annular part]
As shown in FIG. 3, the annular component 100 is manufactured by removing the intermediate portion of the top plate 10 including the two projecting portions 11 of the top plate 10 from the press-formed product 100A. A through hole 12 is formed in the top plate 10 from which the intermediate portion is removed. The through hole 12 penetrates the top plate 10 in the thickness direction of the top plate 10 .
For example, the annular component 100 can be applied to a frame such as a window frame of a vehicle, or a component that constitutes an A-pillar.

[Press forming equipment]
Next, the press molding device will be described.
As shown in FIGS. 4 and 5, the press molding device 200 includes a punch 210, a die 220, a blank holder 230, and a biasing member 240. As shown in FIG. Note that the biasing member 240 is not shown in FIG. The biasing member 240 may be one used in conventional press forming equipment, such as a hydraulic mechanism. FIG. 5 is a cross-sectional view taken along line A5-A5 in FIG.
The punch 210 has a base 211 , a punch portion 212 and a convex portion 213 . The punch portion 212 and the convex portion 213 are essential, but the base 211 may be omitted. Without the base 211 , the biasing member 240 is supported by a base separate from the punch 210 .

For example, the base 211 is formed in a flat plate shape.
The punch part 212 is formed in a shape corresponding to the top plate 10 and the peripheral wall 20 of the press-formed product 100A. The punch portion 212 protrudes from an intermediate portion of a surface 211 a of the base 211 facing the thickness direction of the base 211 . The punch part 212 is formed in a tapered shape in which the cross-sectional area perpendicular to the direction of projection becomes narrower as the projection length increases. In other words, the punch part 212 is formed in the shape of a truncated quadrangular pyramid with rounded corners. The punch part 212 has a rectangular shape with rounded corners, corresponding to the top plate 10 of the press-formed product 100A, when viewed in the projecting direction.

The press direction is the direction in which the mold moves toward the object to be molded during press molding. If the die 220 moves toward the punch 210 during press molding, the press direction is E2 in FIGS. If the punch 210 moves toward the die 220 during press molding, the press direction is E1 in FIGS. Even if the pressing direction is E1 or E2, if there is no difference in the relative positional relationship of the molds, there is no difference in molding. Therefore, in general description, the press direction means the axial direction of E1 and E2, and the orientation of the press direction is not taken into consideration. In the following description, to facilitate understanding of the description of the present disclosure, the direction from the punch 210 to the die 220 is referred to as the press direction E1, and the direction from the die 220 to the punch 210 is referred to as the anti-press direction E2. A direction F along the short side of the punch portion 212 (hereinafter referred to as the short side direction) and a direction along the long side of the punch portion 212 (hereinafter referred to as the long side direction; extending direction) G are respectively It is perpendicular to the pressing direction E1.

The punch portion 212 has a convex shape toward the die 220 . The punch portion 212 is formed with a top surface 212a, a side surface 212b, and a punch shoulder 212c.
The top surface 212a is the tip surface of the punch portion 212 in the pressing direction E1.
The side surface 212b is a side surface of the punch part 212 with respect to the pressing direction E1. The side surface 212b is formed over the entire periphery of the top surface 212a.
The punch shoulder 212c is arranged in the punch portion 212 between the top surface 212a and the side surface 212b (connection portion). In other words, top surface 212a and side surface 212b are connected via punch shoulder 212c. Punch shoulder 212c is the ridgeline between top surface 212a and side surface 212b.

As shown in FIG. 4, the punch shoulder 212c includes punch shoulder straight portions 212c1 and 212c2 and a punch shoulder curved portion 212c3.
The punch shoulder straight portions 212c1 and 212c2 extend with a radius of curvature of 500 mm or more. In this example, the punch shoulder straight portion 212c1 extends along the short side direction F. As shown in FIG. In this example, the punch shoulder straight portion 212c2 extends along the long side direction G. As shown in FIG.
The punch shoulder curved portion 212c3 extends with a radius of curvature of less than 500 mm. The punch shoulder curved portion 212c3 continues to the end of the straight punch shoulder portion 212c1 in the short side direction F and the end of the straight punch shoulder portion 212c2 in the long side direction G, respectively. When viewed from the pressing direction E1 (viewed along the pressing direction E1), the center angle of the punch shoulder curved portion 212c3 is about 90°.
A portion of the top surface 212a adjacent to the punch shoulder curved portion 212c3 protrudes outward along the top surface 212a.

As shown in FIGS. 4 and 5, in this example, the punch 210 has two protrusions 213 corresponding to the two protrusions 11 of the press-formed product 100A. The two convex portions 213 each protrude from the top surface 212a of the punch portion 212 in the pressing direction E1. That is, the top surface 212a of the punch portion 212 has two projections 213 projecting in the pressing direction E1. The protrusion 213 protrudes toward the die 220 . This is the same regardless of whether the press direction defined by the moving direction of the mold during press molding is the press direction E1 or the counter-press direction E2.
Each convex portion 213 extends along the long side direction G. As shown in FIG. The two convex portions 213 are arranged in the short side direction F with a space therebetween. Each convex portion 213 is not formed at the edge of the top surface 212a of the punch portion 212, but is formed at the intermediate portion of the top surface 212a. That is, a flat surface is formed by the top surface 212a between the convex portion 213 and the edge of the top surface 212a.

As shown in FIG. 6, here, a plane passing through the end of the straight punch shoulder portion 212c1 and orthogonal to the straight punch shoulder portion 212c1 is defined as a plane P5. A plane passing through the end of the straight punch shoulder portion 212c2 and orthogonal to the straight punch shoulder portion 212c2 is defined as a plane P6. The planes P5 and P6 are also planes that pass through the end of the punch shoulder curved portion 212c3 and are orthogonal to the punch shoulder curved portion 212c3.
When the press-molded product 100A is manufactured by the press-molding device 200, planes corresponding to the planes P5 and P6 are defined as planes P5A and P6A as shown in FIG.

A portion of the flange 30 sandwiched between the two planes P5A is defined as a flange straight portion 33a. A portion of the flange 30 sandwiched between the two planes P6A is defined as a flange straight portion 33b. A portion of the flange 30 sandwiched between the planes P5A and P6A is defined as a flange curved portion 33c.

When viewed from the pressing direction E1 shown in FIG. 6, the interval in the long side direction G between the tip of the first side G1 in the long side direction G of the convex portion 213 and the center of the straight punch shoulder portion 212c2 is defined as the interval L1. . The interval L1 is preferably 40% or more of the length in the long side direction G of the straight punch shoulder portion 212c2. Here, a first straight line M1 perpendicular to the long side direction G is defined that passes through (connecting portion) between the punch shoulder straight portion 212c2 and the punch shoulder curved portion 212c3 when viewed from the pressing direction E1. The first straight line M1 is included in the plane P6. As viewed from the pressing direction E1, a second straight line M2 is defined that passes through the central portion of the punch shoulder curved portion 212c3 along the longitudinal direction and is parallel to the first straight line M1. At this time, when viewed from the pressing direction E1, the tip of the first side G1 in the long side direction G of the projection 213 is preferably between the first straight line M1 and the second straight line M2.

FIG. 7 shows a cross section passing through the projection 213 and perpendicular to the long side direction G. As shown in FIG. The direction perpendicular to the pressing direction E1 along this cross section is the short side direction F. As shown in FIG. In this cross section, the length of the surface of the protrusion 213 is preferably greater than 1.2 times the width of the protrusion 213 in the direction F of the short side.
Here, the cross sections along the pressing direction E1 and the long side direction G are cross sections perpendicular to the short side direction F. As shown in FIG. FIG. 8 shows a cross section passing through the projection 213 and perpendicular to the short side direction F. As shown in FIG. In this cross section, the angle θ1 between the surface of the tip of the projection 213 in the long side direction G and the pressing direction E1 is preferably 30° or more.

When manufacturing the press-formed product shown in FIG. 17, the centroid of the top surface 212a of the punch portion 212 is positioned inside the top portion of 20% or more of the height of the convex portion 213 in the pressing direction E1 when viewed from the pressing direction E1. Preferably. The centroid of the top surface 212a referred to here means the center of gravity of the top surface 212a when the projections 213 are not formed on the top surface 212a. The apex of 20% or more of the height in the pressing direction E1 of the convex portion 213 is 20% of the height in the pressing direction E1 of the convex portion 213 in the counter-pressing direction E2 from the end of the convex portion 213 in the pressing direction E1. means the range of
2 and 17, both sides of the punch shoulder curved portion 212c3 shown in FIG. Since the angle θ2 formed by the two punch shoulder straight portions 212c1 and 212c2 at is an acute angle, the effects of the present disclosure are likely to be exhibited.

As shown in FIGS. 4 and 5, for example, die 220 is a block of metal. The surface of the die 220 facing the counter-pressing direction E2 is a plate pressing surface 220a.
A plate pressing surface 220 a of the die 220 is formed with a die hole 221 recessed in the shape of the punch portion 212 . The bottom surface 221 a of the die hole 221 has a shape corresponding to the top surface 212 a of the punch 210 . In other words, the bottom surface 221a has a shape in which the unevenness of the top surface 212a is reversed in the pressing direction E1. Strictly speaking, the bottom surface 221a has a shape in which the top surface 212a is extended along the top surface 212a to the outside of the edge of the top surface 212a by the thickness of the metal plate S described later.
Two concave portions 222 corresponding to the two convex portions 213 of the punch 210 are formed in the bottom surface 221 a of the die hole 221 . Each recess 222 extends along the long side direction G. As shown in FIG. The two recesses 222 are spaced apart from each other in the direction F of the short side.

For example, the blank holder 230 is formed in a flat plate shape. A through hole 231 corresponding to the punch portion 212 of the punch 210 is formed in the central portion of the blank holder 230 . The through hole 231 penetrates the blank holder 230 in the pressing direction E1. The punch part 212 can be inserted into the through hole 231 in the pressing direction E1.
The blank holder 230 is arranged between the base 211 of the punch 210 and the plate pressing surface 220 a of the die 220 . If the punch 210 does not have the base 211, the biasing member 240 that supports the blank holder 230 from the counter-pressing direction E2 is supported by a base (not shown). In any case, the blank holder 230 is arranged so as to face the plate holding surface 220a of the die 220 .
The die 220 and the blank holder 230 can sandwich the metal plate S, which is the material for forming the press-formed product 100A.

As shown in FIG. 5, the press forming device 200 includes a plurality of biasing members 240 in this example. For example, biasing member 240 is a spring. Each biasing member 240 is fixed to the surface 211a of the base 211 so as to sandwich the punch portion 212 in the short side direction F. As shown in FIG. Each biasing member 240 extends from the base 211 in the pressing direction E1. Each biasing member 240 is fixed to the surface of the blank holder 230 facing the counter-pressing direction E2.
Note that the biasing member 240 is not limited to a spring, and may be a hydraulic cylinder or the like.

Note that the press molding device 200 does not have to include the biasing member 240 . In this case, the blank holder 230 does not move, and the die 220 moves toward the blank holder 230 to sandwich the metal plate S therebetween. After that, the punch 210 moves in the press direction E1 to perform press molding.

[Manufacturing method of press-molded product]
Next, a method for manufacturing a press-molded product using the press-molding apparatus 200 will be described. FIG. 9 is a flow chart showing a method S1 for manufacturing a press-formed product according to one embodiment of the present invention. The tensile strength of the metal plate S used in the press-formed product manufacturing method S1 is 980 MPa (megapascal) or more.
First, in step S5 shown in FIG. 9, the metal plate S is clamped between the die 220 and the blank holder 230 by the biasing force of the biasing member 240 as shown in FIG. 5 (hereinafter referred to as clamping step S5). After the sandwiching step S5 is completed, the process proceeds to step S6.

Next, in step S6, as shown in FIGS. 10 and 11, the punch 210 is moved in the press direction E1 with respect to the die 220, and the metal plate S is drawn by the press forming device 200 (hereinafter referred to as drawing called step S6). 10 is a cross-sectional view in the middle of the drawing process S6, and FIG. 11 is a cross-sectional view at the end of the drawing process S6. As shown in FIG. 10, the metal plate S is stretched in the pressing direction E1 by the two projections 213. As shown in FIG.
By performing the drawing step S6, the top plate 10, the two protrusions 11, the peripheral wall 20, and the flange 30 are simultaneously formed on the metal plate S to manufacture the press-formed product 100A. The two protrusions 11 are formed by two protrusions 213 of the punch 210 and two recesses 222 of the die 220 .
After the drawing step S6 is completed, the process proceeds to step S7.

Next, in step S7, an intermediate portion of the top plate 10 (the portion formed into the metal plate S by the two projections 213) is removed from the press-formed product 100A by a press-forming device or the like different from the press-forming device 200. Remove (hereinafter referred to as removal step S7). In the removing step S7, the two protrusions 11 on the press-formed product 100A are removed. The removing step S7 is a step performed after the drawing step S6.
When the removing step S7 is finished, all the steps of the press-formed product manufacturing method S1 are finished, and the annular component 100 is manufactured. A press-formed product manufacturing method S1 includes a sandwiching step S5, a drawing step S6, and a removing step S7.

It should be noted that if the through hole 12 is not formed in the annular component 100, the removal step S7 may not be performed in the method of manufacturing the press-formed product.

[Behavior of metal plate when producing press-formed product]
In the following, a configuration without the two projecting portions 11 is referred to as a comparative example press-formed product 100B as shown in FIG. 12 with respect to each configuration of the press-formed product 100A. FIG. 12 shows the process of drawing the metal plate S into the press-formed product 100B of the comparative example. In FIG. 12 and FIG. 13, which will be described later, the metal plate S is hatched so that the deformation can be easily understood.

In the press-formed product 100B of the comparative example, the connecting portion between the top plate 10 and the peripheral wall 20 and formed by the punch shoulder 212c of the punch portion 212 is referred to as the shoulder 14. As shown in FIG. The shoulder 14 is a convex edge. Of the shoulder 14, the portions formed by the punch shoulder straight portions 212c1 and 212c2 and the punch shoulder curved portion 212c3 of the punch shoulder 212c are called shoulder straight portions 14a1 and 14a2 and shoulder curved portion 14a3, respectively.
In the press-formed product 100B of the comparative example, the connecting portion between the peripheral wall 20 and the flange 30 is called a recess 31. As shown in FIG. The depression 31 is a concave ridgeline. The portions of the recess 31 corresponding to the straight shoulder portions 14a1 and 14a2 and the curved shoulder portion 14a3 around the outer peripheral edge Se of the metal plate S are referred to as straight recess portions 31a1 and 31a2 and a curved recess portion 31a3.

In FIG. 12 and FIG. 13 described later, the end of the linear arrow B1 represents the position before drawing of the edge of the press-formed products 100A and 100B, and the end of the linear arrow B1 represents the press-formed after forming. A point on the edges of items 100A and 100B represents the moved position.
During draw forming, the outer peripheral edge Se of the metal plate S indicated by the two-dot chain line moves (displaces) toward the die hole 221 at any position of the outer peripheral edge Se as indicated by the linear arrow. Then, the element α of the metal plate S on the recessed curved portion 31a3 is compressed along the recessed curved portion 31a3 as indicated by the white arrow. The element β of the metal plate S on the shoulder curved portion 14a3 is pulled along the shoulder curved portion 14a3 and further pulled toward the center of the top plate 10 from the flange 30, as indicated by the white arrow. .

That is, element α is shrink-flanged. Element β is bulged.
The term "shrink flange forming" as used herein means forming in which a material such as a metal plate shrinks in the extending direction of the ridge line when the material is drawn toward the ridge line. Stretch flange forming means forming in which the material is stretched in the extending direction of the ridge line when the material is drawn toward the ridge line.

FIG. 13 shows the forming of the press-formed article 100A of the present disclosure.
In FIG. 13, white arrows B4 to B6 indicate changes in the amount of inflow of the metal sheet S from FIG. In FIG. 13, the white arrow B4 indicates that there is a projecting portion 11 extending in the direction along the long side (the direction along the straight shoulder portion 14a2), so the inflow of the metal plate S from the flange 30 toward the top plate 10 has increased. means that The white arrow B5 means that the flange curved portion 33c is stretched under the influence of the inflow of the white arrow B4. A white arrow B6 adjacent to the element α means that the flange curved portion 33c is affected by being stretched, and the contraction flanging of the element α is relaxed.

In the press forming apparatus 200, the punch 210 has two protrusions 213, so the metal sheet S flows in at the initial stage of stretch flanging or shrink flanging. At the same time as the inflow of the metal plate S indicated by the white arrow B4 in FIG. Due to the outflow of the curved portion of the outer peripheral edge Se of the metal plate S, the occurrence of wrinkles due to shrinkage flange forming of the element α is suppressed. Furthermore, the deformation resistance of the element α shrink flanging is mitigated. When the deformation resistance of the element α is relaxed, the amount of material flowing from the element α to the element β increases. As a result, the occurrence of cracks due to stretch flanging of the element β is suppressed.

Comparing FIG. 13 with FIG. 12, it can be seen that the edges of the press-formed products 100A and 100B are displaced by molding from the flange curved portion 33c toward the flange straight portions 33a and 33b as indicated by white arrows B5 and B6. . Since the shrink-flange forming of the element α is relaxed, wrinkles are less likely to occur in the element α. As a result of the relaxation of the shrinkage flanging of the element α, the inflow resistance of the element β toward the top plate is relaxed, and cracks are less likely to occur in the element β.

Thus, in the press-formed product 100A, it is possible to suppress the strain that occurs near the curved portions 14a3 and 31a3. Therefore, it is possible to suppress defects that are likely to occur near the curved portions 14a3 and 31a3 during draw forming.

Here, in the press-formed product 100A, a case where recesses are formed on the first surface 10a of the top plate 10 instead of the protrusions 11 will be described. In this case, as shown in FIG. 10, the punch 210 is formed with a concave portion 214 instead of the convex portion 213, and the die 220 is formed with a convex portion 223 instead of the concave portion 222, as shown in FIG. The concave portion 214 of the punch 210 and the convex portion 223 of the die 220 form a concave portion in the press-formed product 100A.

In this case, the inflow of the metal sheet S occurs at the end of stretch flanging or shrink flanging. That is, the same stretch flanging and shrink flanging as in the absence of the concave portion 214 and the convex portion 223 occur until the final stage of forming of the press-formed product. Furthermore, since the metal sheet S is restrained by the punch 210 and the die 220 at the final stage of forming, a large inflow of the metal sheet S does not occur. Instead, the metal plate S near the recess 214 is stretched.
As an adverse effect, there is concern that the recess 214 will pull the element β toward the top plate 10 and crack it.

[Examination of each parameter when manufacturing press-formed products]
Below, the examination result of each parameter at the time of manufacturing a press-formed article is demonstrated.
Here, as shown in FIG. 2, the distance from the center 10c in the direction along the long side of the top plate 10 to the tip 11a on the first side in the direction along the long side of the projecting portion 11 is defined as a distance De. . A distance from the center 10c of the top plate 10 to a boundary P1 between the straight shoulder portion 14a2 and the curved shoulder portion 14a3 is defined as a distance Ds.
At a predetermined portion of the metal plate S (the press-formed product 100A), the plate thickness before drawing is defined as tb, and the plate thickness after drawing is defined as ta. A plate thickness reduction rate r of a predetermined portion is defined as (tb-ta)/tb.

When the plate thickness reduction rate r is a positive value, it means that the plate thickness of the predetermined portion is reduced, and when the plate thickness reduction rate r is a negative value, the plate thickness of the predetermined portion is increased. means
From another point of view, when the metal plate is formed across the curved ridge line of the mold, the place where the plate thickness reduction rate r is a positive value means that stretch flanging is performed, Negative values indicate shrink-flanging.

The plate thickness reduction rate r of the press-formed product 100A is defined as the plate thickness reduction rate ra, and the plate thickness reduction rate r of the comparative example press-formed product 100B is defined as the plate thickness reduction rate rb. Then, the plate thickness reduction rate ratio is defined as (rb-ra)/rb.

In the studied example, the depth of the protrusion 11 in the press-formed product 100A was set to 10 mm. The drawing depth by drawing, that is, the distance from the flange 30 to the second surface 10b of the top plate 10 was set to 50 mm. The radius of curvature of the curved shoulder portion 14a3 was set to 90 mm. The angle formed by the second surface 10b of the top plate 10 and the peripheral wall 20 was set to 100°.
The plate thickness reduction rate ratio was measured from point t1 to point t4 in the press-formed product 100A shown in FIG.

FIG. 14 is a diagram showing the relationship between the (De/Ds) value and the plate thickness reduction rate ratio.
Improvement effect of plate thickness reduction rate ratio of each part (t1 to t4) before and after draw forming shown in FIG. verified. Changing the position of this tip changes the value of (De/Ds).

In FIG. 13, when the plate thickness reduction rate ratio is a positive value, it means that the deformation due to inflow shrink flanging or stretch flanging outflow is alleviated by the projecting portion 11 . If the plate thickness reduction rate ratio is a negative value, it means that the amount of inflow or outflow deformation is increased by the projecting portion 11 .

It was found that when the value of (De/Ds) is 0.8 or more, the plate thickness reduction rate ratio increases significantly. In other words, it was found that when the tip 11a of the projecting portion 11 was closer to the first side in the direction along the long side, the change in plate thickness before and after draw forming was reduced and improved.

FIG. 7 shows a cross section orthogonal to the direction along the long side, where the depth Hp of the protruding portion 11 is maximum. The extended length of the surface of the projecting portion 11 in this cross section is defined as an acceleration line length Lp. The length between both ends of the cross section of the projecting portion 11 is defined as a reference line length Ls. The ratio of the enhancement line length Lp to the reference line length Ls is defined as the line length ratio (Lp/Ls).
FIG. 15 shows changes in the plate thickness reduction rate ratio with respect to the line length ratio (Lp/Ls). It can be seen from FIG. 15 that when the line length ratio (Lp/Ls) exceeds 1.20, the plate thickness reduction rate ratio increases. That is, when the line length ratio (Lp/Ls) is more than 1.20, the plate thickness change before and after draw forming is moderated.
Therefore, it is preferable that the line length ratio (Lp/Ls) of the protruding portion 11 of the press-formed product 100A is more than 1.20. In other words, the ratio between the acceleration line length Lp and the reference line length Ls of the projecting portion 11 is preferably greater than 1.20.

FIG. 16 shows changes in the plate thickness reduction rate ratio with respect to the depth Hp of the protruding portion 11 .
From FIG. 16, it was found that it is more preferable for the projecting portion 11 to have a cross-section with a depth Hp of 10 mm or more.

[Effect of this embodiment]
As explained above, in the press-molding apparatus 200 of this embodiment, the punch 210, the die 220, and the blank holder 230 manufacture the press-molded product 100A. At this time, the portion of the top surface 212a adjacent to the punch shoulder curved portion 212c3 protrudes outwardly from the top surface 212a, and the top surface 212a of the punch portion 212 has two protrusions 213. As shown in FIG. Therefore, when the metal plate S is drawn, for example, the two convex portions 213 of the punch 210 pull the portions of the metal plate S that will become the curved portions 14a3 and 31a3 of the press-formed product 100A.
Therefore, when the press-molded product 100A is manufactured by the press-molding device 200, defects such as wrinkles and cracks occurring in the curved portions 14a3 and 31a3 of the press-molded product 100A can be suppressed.

The distance between the tip of the convex portion 213 and the center of the straight punch shoulder portion 212c2 may be 40% or more of the length in the long side direction G of the straight punch shoulder portion 212c2. This corresponds to the case where De/Ds in FIG. 14 is 0.8 or more. In this case, it is possible to alleviate the plate thickness change due to press forming.
The tip of the first side G1 in the long side direction G of the convex portion 213 may be between the first straight line M1 and the second straight line M2. In this case, the flow of the metal sheet S from the flange curved portion 33c to the flange straight portions 33a and 33b can be increased, and an increase in strain in the flange curved portion 33c caused by drawing can be suppressed. Therefore, the occurrence of defects such as cracks and wrinkles in the curved portions 14a3 and 31a3 of the annular component 100 can be suppressed.

In a cross section transverse to the longitudinal direction of the projection 213, the length of the surface of the projection 213 may be greater than 1.2 times the width of the projection 213 in the short side direction F. This corresponds to the case where Lp/Ls in FIG. 15 is 1.2 or more. In this case, it is possible to alleviate the plate thickness change due to press forming.
The angle θ1 between the surface of the tip of the projection 213 in the long side direction G and the pressing direction E1 may be 30° or more. In this case, it is possible to suppress the occurrence of local distortion due to the molding of the projecting portion 11 itself, and the metal plate S is smoothly moved along the top plate 10 from the flange curved portion 33c toward the flange straight portions 33a and 33b. can flow. Therefore, it is possible to manufacture the annular component 100 that suppresses defects occurring in the curved portions 14a3 and 31a3.

The centroid of the top surface 212a of the punch portion 212 may be inside the top portion of 20% or more of the height of the convex portion 213 in the pressing direction E1. In this case, the material inflow rate can be increased over the entire circumference of the annular ridge line 213c.
The angle θ2 formed by the punch shoulder straight portions 212c1 and 212c2 may be an acute angle. In this case, the change in plate thickness due to press forming is greater than when the normal angle θ2 is a right angle, so the effect of the present disclosure becomes more conspicuous.

Moreover, in the press molding apparatus 200 of this embodiment, the pinching step S5 and the drawing step S6 are performed. And when the tensile strength of the metal plate S is 980 MPa or more, the problem due to the plate thickness change due to press forming becomes apparent, so the effect of the present disclosure becomes more apparent.
By performing the removing step S7 after the drawing step S6, the intermediate portion of the top plate 10 can be removed from the press-formed product 100A, and the annular component 100 can be manufactured.

[Modified example of press-molded product and annular part]
As shown in FIG. 17, the press-formed product 101A of the first modified example has one protrusion 11 for the two protrusions 11 in each configuration of the press-formed product 100A of the present embodiment.
FIG. 18 shows the result of determining the relationship between the value of (De/Ds) and the plate thickness reduction rate ratio for the press-formed product 101A. It was found that the press-formed product 101A having one projecting portion 11 also provided the same effect as the press-formed product 100A having two projecting portions 11.

As shown in FIG. 19, the press-formed product 101B of the second modified example has three protrusions 11 in contrast to the two protrusions 11 in each configuration of the press-formed product 100A of the present embodiment. The three protruding portions 11 are spaced apart from each other in the direction along the short side.
As shown in FIG. 20, the press-formed product 101C of the third modification has four protrusions 11 in contrast to the two protrusions 11 in each configuration of the press-formed product 100A of the present embodiment. A set of protrusions 11 constituted by two protrusions 11 out of the four protrusions 11 are arranged side by side with an interval in the direction along the long side. The two sets of protrusions 11 are arranged side by side with a space therebetween in the direction along the short side.

That is, when the projecting portion 11 extends along the straight shoulder portion 14a2 from a portion adjacent to the curved shoulder portion 14a3 of the straight shoulder portion 14a2 adjacent to the outside of the top plate 10, the curved flange portion 33c is formed. It has the effect of alleviating shrinkage flanging. At this time, the projecting portion 11 does not necessarily need to extend to the central portion of the straight shoulder portion 14a2.

As shown in FIG. 21, the top plate 40 of the press-formed product 101D of the fourth modification has a triangular shape with rounded corners when viewed in the thickness direction of the top plate 40 .
One projecting portion 41 is formed on the top plate 40 . The projecting portion 41 has a triangular shape with rounded corners, which is similar to the top plate 40 when viewed in the thickness direction of the top plate 40 .
That is, even if it is configured like the press-formed product 101D, it is possible to cause the inflow of the metal plate S in the same manner as indicated by the white arrow B4 in FIG.

The press-formed products 101A, 101B, 101C, and 101D of the modified examples configured as described above can also achieve the same effects as the press-formed product 100A of the present embodiment.

As shown in FIG. 22 , the top plate 45 of the annular component 102A of the first modified example has an oval shape when viewed in the thickness direction of the top plate 45 . A through hole 46 is formed in the top plate 45 so as to pass through the top plate 45 in the thickness direction.
As shown in FIG. 23 , the top plate 50 of the annular component 102B of the second modified example has a triangular shape with rounded corners when viewed in the thickness direction of the top plate 50 .
As shown in FIG. 24 , the top plate 55 of the annular component 102</b>C of the third modification has a pentagonal shape when viewed in the thickness direction of the top plate 55 .

As described above, one embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and the configuration can be changed, combined, or deleted without departing from the scope of the present invention. etc. are also included.

According to the present invention, it is possible to provide a press-molding apparatus and a method of manufacturing a press-molded product that can suppress defects occurring in the curved portion of the molded product. Therefore, industrial applicability is great.

200 press molding device 210 punch 212a top surface 212b side surface 212c punch shoulders 212c1, 212c2 punch shoulder straight portion 212c3 punch shoulder curved portion 213 convex portion 220 die 220a plate holding surface 230 blank holder E1 press direction G long side direction (along the long side direction, direction of extension)
L1 Spacing M1 First straight line M2 Second straight line S Metal plate S1 Press-formed product manufacturing method S5 Sandwiching process S6 Drawing process S7 Removing process θ1, θ2 Angles

Claims (9)

1. comprising a punch, a die and a blank holder;
   the punch has a top surface, a side surface, and a punch shoulder positioned between the top surface and the side surface;
   The punch shoulder includes a punch shoulder straight portion extending with a curvature radius of 500 mm or more and a punch shoulder curved portion extending with a curvature radius of less than 500 mm,
   a portion of the top surface adjacent to the punch shoulder curved portion protrudes outwardly from the top surface;
   The top surface has a protrusion projecting in the pressing direction,
   The convex portion extends along the direction in which the punch shoulder straight portion extends,
   The bottom surface of the die hole of the die has a shape corresponding to the top surface,
   The press molding apparatus, wherein the blank holder is arranged to face the plate holding surface of the die.
2. Seen from the press direction,
   4. The distance in the extending direction between the tip of the projection in the extending direction and the center of the straight punch shoulder portion is 40% or more of the length of the straight punch shoulder portion in the extending direction. 1. The press molding apparatus according to 1.
3. Seen from the press direction,
   A first straight line that passes between the punch shoulder straight portion and the punch shoulder curved portion and is perpendicular to the extending direction, and a second straight line that passes through the central portion of the punch shoulder curved portion and is parallel to the first straight line. 3. The press forming apparatus according to claim 2, wherein there is said tip of said projection therebetween.
4. In a cross section passing through the convex portion and perpendicular to the extending direction,
   4. The press forming apparatus according to any one of claims 1 to 3, wherein the length of the surface of the convex portion is greater than 1.2 times the width of the convex portion perpendicular to the pressing direction.
5. In cross sections along the pressing direction and the extending direction through the convex portion,
   The press forming apparatus according to any one of claims 2 to 4, wherein an angle formed by a surface of the tip portion of the projection in the extending direction and the pressing direction is 30° or more.
6. Seen from the press direction,
   6. The press forming apparatus according to any one of claims 1 to 5, wherein the centroid of the top surface is inside a top portion that is 20% or more of the height of the convex portion in the pressing direction.
7. The press forming apparatus according to any one of claims 1 to 6, wherein the two punch shoulder straight portions on both sides of the punch shoulder curved portion form an acute angle.
8. A method for manufacturing a press-formed product using the press-forming apparatus according to any one of claims 1 to 7,
   sandwiching a metal plate between the die and the blank holder;
   Draw forming the metal plate with the press forming device,
   A method for producing a press-formed product, wherein the metal plate has a tensile strength of 980 MPa or more.
9. The method for manufacturing a press-formed product according to claim 8, wherein the portion formed on the metal plate is removed by the convex portion.

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