JP7343766B2 - Press molding mold and press molding equipment - Google Patents

Description

The present invention relates to a press molding die and a press molding apparatus.

In recent years, there has been an increasing need to reduce the weight of automobile bodies due to environmental issues. The main ways to reduce weight include reducing the thickness of the steel plate that the car body is made of, and replacing the steel plate with another material (aluminum plate, magnesium plate, titanium plate, etc.). be. However, regardless of the type of material, when manufacturing car body frame parts by applying plastic processing to metal plates (blanks), an elastic recovery phenomenon (so-called springback) occurs, and molded products aimed at metal plates There is a problem that it cannot be processed into the shape of .

For example, Patent Document 1 below describes a method for correcting springback that occurs in a molded product obtained by press forming, in which a reverse bending radius portion is formed in the opposite direction to the molding bending direction along the bending ridge line of the molded product. , a method is disclosed in which a moment in the opposite direction to the springback moment is generated by this reverse bending radius portion.

For example, Patent Document 2 below describes a method for suppressing springback that occurs in a bent shoulder formed by press bending a metal plate into a substantially L shape. When doing this, by forming a concave stepped part that is continuously recessed along the ridgeline of the bending shoulder in the opposite direction to the forming bending direction, and then forming this reverse recess into a convex part, approximately A method of forming an L-shaped bending shoulder is disclosed.

For example, Patent Document 3 below describes a method for suppressing springback that occurs in a bent shoulder formed by press bending a metal plate. A concave stepped portion recessed in a direction opposite to the forming bending direction of the bending shoulder is provided in parallel to the ridge line of the bending shoulder, and a punch having a convex curvature portion, and convex portions on both sides of the concave curvature corresponding to the punch. A method is disclosed for simultaneously forming the bent shoulder and the concave shape using a die.

Patent No. 3473868 Patent No. 3379595 Patent No. 3442122

In the method disclosed in the above-mentioned Patent Document 1, by additionally processing a molded product obtained by press forming, a reverse bending radius portion in the opposite direction to the molding bending direction is formed along the bending ridge line of the molded product. Since it is necessary to mold, there is a problem that the manufacturing process becomes complicated and the degree of freedom in designing the shape of the ultimately required molded product is restricted.

In the method disclosed in Patent Document 2, when bending and forming a substantially L-shaped bending shoulder, the bending shoulder is first formed in a continuous manner along the ridgeline of the bending shoulder in a direction opposite to the bending direction. After forming the concave stepped portion, it is then necessary to form the approximately L-shaped bent shoulder by forming the inverted concave portion into a convex portion. There is a problem of complication.

In the method disclosed in Patent Document 3, a concave stepped portion is formed in the bending shoulder in the finally obtained molded product, so the degree of freedom in the shape design of the molded product is There is a problem that there are restrictions on

The present invention has been made in view of the above circumstances, and it is possible to suppress springback occurring in a molded product without complicating the manufacturing process and without restricting the degree of freedom in designing the shape of the molded product. An object of the present invention is to provide a press molding mold and a press molding device equipped with the same.

For example, as shown in FIG. 9, when manufacturing a hat-shaped molded product 100 consisting of a top plate portion 101, a pair of vertical wall portions 102, and a pair of flange portions 103, the blank is Generally, drawing is performed while applying tension. In this case, as shown in FIG. 10, wall warpage occurs in the pair of vertical wall portions 102 due to springback.

FIG. 11 is a diagram schematically showing a general press molding method for producing a hat-shaped molded product 100 from a blank 200 that is a metal plate. As shown in FIG. 11(a), the general press forming method uses a die (upper mold) 300, a blank holder 400, and a punch 500. FIG. 11(b) is an enlarged view of area A1 in FIG. 11(a).

The die 300 has an end surface 310 (hereinafter referred to as a blank pressing surface) provided on one side (lower side) in the height direction Z so as to be orthogonal to the height direction Z, and It has a recess 320 that is recessed on the other side (upper side) in the width direction Z and is provided so as to extend in the length direction X. A first vertical wall surface 321 parallel to the height direction Z exists on one side (right side) in the width direction Y as a surface forming the outline of the recessed portion 320, and the first vertical wall surface 321 and the blank pressing surface 310 are 1 They are connected by a curved surface 322 (hereinafter referred to as a first die shoulder surface) having two curvatures.
The blank holder 400 has a blank support surface 410 that faces the blank pressing surface 310 of the die 300. The punch 500 has a protrusion 510 that can be inserted into the recess 320 of the die 300.

As shown in FIG. 11(a), the protrusion 510 is inserted into the recess 320 with the blank 200 sandwiched between the blank pressing surface 310 of the die 300 and the blank support surface 410 of the blank holder 400. By raising the punch 500 to the top dead center, the blank 200 is drawn and formed into a hat-shaped molded product 100.

FIG. 12(a) shows a state in which the punch 500 is about to reach the top dead center. FIG. 12(b) is an enlarged view of area A2 in FIG. 12(a). As shown in FIG. 12(b), during drawing forming of the blank 200, when material flows from a portion corresponding to the flange portion 103 to a portion corresponding to the vertical wall portion 102, the blank 200 is drawn by the first die shoulder surface 322. When the blank 200 is bent back and deformed, a stress difference is generated between the front and back in the thickness direction of the portion of the blank 200 that is in contact with the first die shoulder surface 322. Because this stress difference remains in the vertical wall portion 102 of the molded product 100, springback occurs in the vertical wall portion 102.

In order to suppress the springback occurring in the vertical wall portion 102 of the molded product 100, the inventors of the present application have conducted extensive studies on means for reducing the stress difference remaining between the front and back sides of the vertical wall portion 102 in the thickness direction. As a result, as shown in FIGS. 13 and 14, the shape of the first die shoulder surface 322 is set so that a space is formed between the first die shoulder surface 322 and the blank 200 when the blank 200 is drawn. It has been found that the difference in stress remaining on the front and back surfaces in the thickness direction of the vertical wall portion 102 of the molded product 100 finally obtained can be reduced.
13(a) and 14(a) both show a state in which the punch 500 is about to reach the top dead center. FIG. 13(b) is an enlarged view of area A3 in FIG. 13(a). FIG. 14(b) is an enlarged view of area A4 in FIG. 14(a).

The reason for this is that, as shown in FIGS. 13 and 14, when a space is formed between the first die shoulder surface 322 and the blank 200 during drawing forming of the blank 200, a vertical wall is formed from a portion corresponding to the flange portion 103. This is thought to be because the stress generated on the front and back sides of the blank 200 in the thickness direction is once reversed (the positive and negative signs of the stress are reversed) when the material flows into the portion corresponding to the portion 102.

According to the above means, it is possible to suppress the springback that occurs in the molded product 100 simply by changing the shape of the first die shoulder surface 322 of the die 300, so that the manufacturing process is not complicated as in the conventional technology. In addition, the degree of freedom in designing the shape of the molded product 100 is not restricted.

The present invention has been completed based on the above findings, and employs the following means to solve the above problems and achieve the objects.
(1) A press molding die for a hat-shaped molded product according to one aspect of the present invention has an end surface provided on one side in the height direction so as to intersect with the height direction, and a A press molding die having a recess provided to be recessed on the other side in the width direction and extending in the length direction, the first mold extending in the height direction as a surface forming the outline of the recess. A vertical wall surface exists on one side in the width direction, the first vertical wall surface and the end surface are connected by a first die shoulder surface having n curvatures, and the first vertical wall surface is connected to the first vertical wall surface at the first die shoulder surface. When the curvatures are numbered in order in the direction toward the end surface, there is at least one s-th curvature ρ(s) that satisfies the following relational expression (1).
ρ(s)<ρ(s-1), and ρ(s)<ρ(s+1)...(1)
(However, n≧3, 2≦s≦n-1)

(2) In the press molding die according to (1) above, a second vertical wall surface extending in the height direction as a surface forming an outline of the recess is present on the other side in the width direction, and The wall surface and the end surface may be connected by a second die shoulder surface having n curvatures. Even in this case, when numbers are given to the curvatures in order from the second vertical wall surface toward the end surface on the second die shoulder surface, the s-th curvature ρ(s) that satisfies the above relational expression (1) is It is desirable that at least one exists.

(3) A press molding apparatus according to one aspect of the present invention includes the press molding die according to (1) or (2) above, and a blank support surface facing the end surface of the press molding die. The punch includes a blank holder and a punch having a convex portion that can be inserted into the recess of the press mold.

According to the above aspect of the present invention, the press molding die is capable of suppressing springback occurring in a molded product without complicating the manufacturing process and without restricting the degree of freedom in designing the shape of the molded product. , and a press molding device equipped with the same.

1 is a diagram schematically showing the configuration of a press molding die 10 according to a first embodiment of the present invention. 1 is a diagram schematically showing a press molding apparatus 60 equipped with a press molding die 10 according to a first embodiment of the present invention. It is a figure which shows typically the structure of the press molding die 20 based on 2nd Embodiment of this invention. It is a figure which shows typically the press molding apparatus 70 equipped with the press molding die 20 based on 2nd Embodiment of this invention. The final results are shown for each of the cases where the press molding die 10 of the first embodiment is used, the press molding die 20 of the second embodiment is used, and the general die 300 is used. A stress contour diagram shows the results of a simulation analysis of the stress difference remaining on the front and back surfaces in the thickness direction of the vertical wall of the hat-shaped molded product obtained. The final results are shown for each of the cases where the press molding die 10 of the first embodiment is used, the press molding die 20 of the second embodiment is used, and the general die 300 is used. This figure shows the results of a simulation analysis of the amount of warpage due to springback that occurs in the vertical wall of the hat-shaped molded product obtained in the above. It is an explanatory view about a 1st modification and a 2nd modification. It is an explanatory view about a 3rd modification. 1 is a diagram schematically showing a hat-shaped molded product 100. FIG. FIG. 3 is a diagram schematically showing how wall warpage occurs in a vertical wall portion 102 of a hat-shaped molded product 100 due to springback. FIG. 2 is a diagram schematically showing a general press molding method for producing a hat-shaped molded product 100 from a blank 200 that is a metal plate. FIG. 2 is a diagram schematically showing a general press molding method for producing a hat-shaped molded product 100 from a blank 200 that is a metal plate. By setting the shape of the first die shoulder surface so that a space is formed between the first die shoulder surface and the blank during drawing forming of the blank, the thickness direction of the vertical wall portion of the finally obtained molded product is These are analysis results showing that the stress difference remaining between the front and back sides can be reduced. By setting the shape of the first die shoulder surface so that a space is formed between the first die shoulder surface and the blank during drawing forming of the blank, the thickness direction of the vertical wall portion of the finally obtained molded product is These are analysis results showing that the stress difference remaining between the front and back sides can be reduced.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.
[First embodiment]
First, a first embodiment of the present invention will be described.
FIG. 1 is a diagram schematically showing the configuration of a press molding die 10 according to a first embodiment of the present invention. FIG. 1(b) is an enlarged view of region B1 in FIG. 1(a). As shown in FIG. 1, the press molding die 10 according to the first embodiment has an end face 11 (hereinafter referred to as , a blank pressing surface 11), and a recess 12 provided so as to be recessed from the blank pressing surface 11 on the other side (upper side) in the height direction Z and extending in the length direction X. are doing.
In addition, in this embodiment, the end surface 11 orthogonal to the height direction Z is illustrated as the "end surface intersecting the height direction." In other words, the end surface 11 is a surface that intersects the height direction Z at an angle of 90 degrees. However, the present invention is not limited thereto, and the end surface 11 may be a surface that intersects the height direction Z at an angle other than 90°.

In the press molding die 10, the first vertical wall surface 13 extending in the height direction Z as a surface forming the contour of the recessed portion 12 exists on one side (right side) in the width direction Y, and the first vertical wall surface 13 and the blank The pressing surface 11 is connected to the first die shoulder surface 14 having n curvatures. On the first die shoulder surface 14, when numbers are assigned to the curvatures in order from the first vertical wall surface 13 toward the blank pressing surface 11, the s-th curvature ρ(s) that satisfies the following relational expression (1) is There is at least one.
ρ(s)<ρ(s-1), and ρ(s)<ρ(s+1)...(1)
(However, n≧3, 2≦s≦n-1)
In this embodiment, the first vertical wall surface 13 extending in parallel to the height direction Z is exemplified as the "first vertical wall surface extending in the height direction," but the present invention is not limited to this, and the first vertical wall surface The wall surface 13 may be a surface extending in the height direction Z while being inclined with respect to the height direction Z.

As shown in FIG. 1(b), when focusing on points P1, P2, and P3 existing on the first die shoulder surface 14, point P1 exists on a circle whose radius of curvature is R1, and point P2 exists on a circle with a radius of curvature R1 ( =∞) exists on a circle (not shown) having a radius of curvature, and point P3 exists on a circle having a radius of curvature R3. Therefore, the first curvature ρ(1) corresponding to point P1 is obtained as the reciprocal of the radius of curvature R1 (1/R1), and the second curvature ρ(2) corresponding to point P2 is obtained as the reciprocal of the radius of curvature R2 ( 1/R2=1/∞=0), and the third curvature ρ(3) corresponding to point P3 is obtained as the reciprocal of the radius of curvature R3 (1/R1).

That is, when focusing on the second curvature ρ(2), the conditions ρ(2)<ρ(1) and ρ(2)<ρ(3) are satisfied, and the press according to the first embodiment The first die shoulder surface 14 of the molding die 10 satisfies the condition that there is at least one s-th curvature ρ(s) that satisfies the above relational expression (1).

Further, in the press molding die 10, a second vertical wall surface 15 extending in the height direction Z as a surface forming the outline of the recess 12 is present on the other side (left side) in the width direction Y. and the blank pressing surface 11 are connected by a second die shoulder surface 16 having n curvatures. Similar to the first die shoulder surface 14, when the curvatures of the second die shoulder surface 16 are sequentially numbered in the direction from the second vertical wall surface 15 toward the blank pressing surface 11, the above relational expression (1) is satisfied. There is at least one sth curvature ρ(s).
Since the second die shoulder surface 16 has the same shape as the first die shoulder surface 14, the reason why the above relational expression (1) is satisfied is also the same as that of the first die shoulder surface 14.
Further, in this embodiment, the second vertical wall surface 15 extending parallel to the height direction Z is exemplified as the "second vertical wall surface extending in the height direction", but the present invention is not limited to this, and the second vertical wall surface 15 is The wall surface 15 may be a surface extending in the height direction Z while being inclined with respect to the height direction Z.

Note that when checking the magnitude relationship of the curvatures, the magnitude relationship is not confirmed by the absolute value of the curvature, but by a value that takes into account the positive and negative signs. In this embodiment, when the center of the radius of curvature is located inside the press molding die 10, as in points P1 and P3 shown in FIG. When the center is located outside the press molding die 10, the sign of the curvature is set to be "negative". Of course, the definitions of positive and negative signs may be reversed.
That is, for example, even if ρ(s) and ρ(s-1) are the same value, the sign of ρ(s) is "positive" and the sign of ρ(s-1) is "negative". In this case, it is determined that ρ(s) is larger than ρ(s−1).

FIG. 2 is a diagram schematically showing a press molding apparatus 60 including a press molding die 10 according to the first embodiment. As shown in FIG. 2(a), this press molding device 60 is used when manufacturing a hat-shaped molded product 100 from a blank 200 that is a metal plate, and is a press molding device 60 that is used for manufacturing a hat-shaped molded product 100 from a blank 200 that is a metal plate, and is used for press molding according to the first embodiment. It includes a mold 10, a blank holder 400, and a punch 500. Note that the same components as those shown in FIG. 11 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 2(a), with the blank 200 sandwiched between the blank pressing surface 11 of the press molding die 10 and the blank support surface 410 of the blank holder 400, the convex portion 510 is inserted into the concave portion 12. By raising the punch 500 to the top dead center so as to be inserted, the blank 200 is drawn and formed into a hat-shaped molded product 100.

FIG. 2(b) shows the punch 500 in a state just before reaching the top dead center. As shown in this figure, when the blank 200 is drawn, a space is formed between the first die shoulder surface 14 and the blank 200, so that from a portion corresponding to the flange portion 103 to a portion corresponding to the vertical wall portion 102. When the material flows into the blank 200, the stress generated on the front and back sides of the blank 200 in the thickness direction is reversed once (see FIG. 13(b)). As a result, it is possible to reduce the stress difference remaining between the front and back surfaces in the thickness direction of the vertical wall portion 102 of the molded product 100 that is finally obtained, so that springback occurring in the vertical wall portion 102 of the molded product 100 can be suppressed.

Moreover, according to the above embodiment, it is possible to suppress the springback that occurs in the molded product 100 simply by replacing the general die 300 with the present press molding die 10. complication, and the degree of freedom in designing the shape of the molded product 100 is not restricted. That is, according to the first embodiment, the press is capable of suppressing springback occurring in the molded product 100 without complicating the manufacturing process and without restricting the degree of freedom in designing the shape of the molded product 100. A molding die 10 and a press molding device 60 equipped with the same can be provided.

[Second embodiment]
Next, a second embodiment of the present invention will be described.
FIG. 3 is a diagram schematically showing the configuration of a press molding die 20 according to a second embodiment of the present invention. FIG. 3(b) is an enlarged view of region B2 in FIG. 3(a). As shown in FIG. 3, the press molding die 20 according to the second embodiment has an end face 21 (hereinafter referred to as , referred to as a blank pressing surface 21), and a recess 22 provided so as to be recessed from the blank pressing surface 21 on the other side (upper side) in the height direction Z and extending in the length direction X. are doing.
Note that in this embodiment as well, the end surface 21 that is orthogonal to the height direction Z is exemplified as the "end surface that intersects in the height direction"; however, the present invention is not limited to this, and the end surface 21 is It may be a plane that intersects at an angle other than 90°.

In the press molding die 20, the first vertical wall surface 23 extending in the height direction Z as a surface forming the contour of the recessed portion 22 exists on one side (right side) in the width direction Y, and the first vertical wall surface 23 and the blank The pressing surface 21 is connected to the first die shoulder surface 24 having n curvatures. On the first die shoulder surface 24, when numbers are assigned to the curvatures in order from the first vertical wall surface 23 toward the blank pressing surface 21, the s-th curvature ρ(s) that satisfies the following relational expression (1) is There is at least one.
ρ(s)<ρ(s-1), and ρ(s)<ρ(s+1)...(1)
(However, n≧3, 2≦s≦n-1)
Note that in this embodiment as well, the first vertical wall surface 23 extending in parallel to the height direction Z is exemplified as the "first vertical wall surface extending in the height direction," but the present invention is not limited to this, and the first vertical wall surface The vertical wall surface 23 may be a surface extending in the height direction Z while being inclined with respect to the height direction Z.

As shown in FIG. 3(b), when focusing on points P1, P2, and P3 that exist on the first die shoulder surface 24, point P1 exists on a circle whose radius of curvature is R1, and point P2 exists on a circle whose radius of curvature is R2. It exists on a circle whose radius of curvature is R3, and point P3 exists on a circle whose radius of curvature is R3. Here, R1=R3 and R2>R1.

The first curvature ρ(1) corresponding to point P1 is obtained as the reciprocal of the radius of curvature R1 (1/R1), and the second curvature ρ(2) corresponding to point P2 is obtained as the reciprocal of the radius of curvature R2 (1/R1). R2), and the third curvature ρ(3) corresponding to point P3 is obtained as the reciprocal of the radius of curvature R3 (1/R3). The signs of the curvature ρ(1) and the curvature ρ(3) are “positive,” and the signs of the curvature ρ(2) are “negative.”

Therefore, when focusing on the second curvature ρ(2), the conditions ρ(2)<ρ(1) and ρ(2)<ρ(3) are satisfied, and the press according to the second embodiment The first die shoulder surface 24 of the molding die 20 satisfies the condition that there is at least one s-th curvature ρ(s) that satisfies the above relational expression (1).

In addition, in the press molding die 20, a second vertical wall surface 25 extending in the height direction Z as a surface forming the outline of the recessed portion 22 is present on the other side (left side) in the width direction Y. and the blank pressing surface 21 are connected by a second die shoulder surface 26 having n curvatures. Similar to the first die shoulder surface 24, when the curvatures of the second die shoulder surface 26 are numbered in order from the second vertical wall surface 25 toward the blank pressing surface 21, the above relational expression (1) is satisfied. There is at least one sth curvature ρ(s).
Since the second die shoulder surface 26 has the same shape as the first die shoulder surface 24, the reason why the above relational expression (1) is satisfied is also the same as that of the first die shoulder surface 24.
Further, in this embodiment as well, the second vertical wall surface 25 extending in parallel to the height direction Z is exemplified as the "second vertical wall surface extending in the height direction", but the present invention is not limited to this, and the second vertical wall surface 25 extends in parallel to the height direction Z. The vertical wall surface 25 may be a surface extending in the height direction Z while being inclined with respect to the height direction Z.

FIG. 4 is a diagram schematically showing a press molding apparatus 70 including a press molding die 20 according to the second embodiment. As shown in FIG. 4(a), this press molding device 70 is used when manufacturing a hat-shaped molded product 100 from a blank 200, which is a metal plate, and is used for press molding according to the second embodiment. It includes a mold 20, a blank holder 400, and a punch 500. Note that the same components as those shown in FIG. 11 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 4(a), with the blank 200 sandwiched between the blank pressing surface 21 of the press molding die 20 and the blank support surface 410 of the blank holder 400, the convex portion 510 is inserted into the concave portion 22. By raising the punch 500 to the top dead center so as to be inserted, the blank 200 is drawn and formed into a hat-shaped molded product 100.

FIG. 4(b) shows the punch 500 in a state just before reaching the top dead center. As shown in this figure, when the blank 200 is drawn, a space is formed between the first die shoulder surface 24 and the blank 200, so that from a portion corresponding to the flange portion 103 to a portion corresponding to the vertical wall portion 102. When the material flows into the blank 200, the stress generated on the front and back sides of the blank 200 in the thickness direction is reversed once (see FIG. 14(b)). As a result, it is possible to reduce the stress difference remaining between the front and back surfaces in the thickness direction of the vertical wall portion 102 of the molded product 100 that is finally obtained, so that springback occurring in the vertical wall portion 102 of the molded product 100 can be suppressed.

Moreover, according to the embodiment described above, it is possible to suppress the springback that occurs in the molded product 100 simply by replacing the general die 300 with the present press molding die 20. complication, and the degree of freedom in designing the shape of the molded product 100 is not restricted. That is, according to the second embodiment, the press can suppress the springback that occurs in the molded product 100 without complicating the manufacturing process and without restricting the degree of freedom in designing the shape of the molded product 100. A molding die 20 and a press molding device 70 equipped with the same can be provided.

〔Analysis result〕
FIG. 5 shows cases in which the press molding die 10 of the first embodiment is used, the press molding die 20 of the second embodiment is used, and a general die 300 is used. The stress contour diagram shows the results of a simulation analysis of the stress difference remaining on the front and back sides in the thickness direction of the vertical wall part (the part surrounded by the solid line C1) of the hat-shaped molded product finally obtained. .

As shown in FIG. 5, as a result of analysis by the inventor of the present application, compared to the case where a general die 300 is used, the case where the press molding die 10 of the first embodiment is used, and the case where the press molding die 10 of the first embodiment is used, It was confirmed that when the press molding die 20 of the embodiment was used, it was possible to reduce the stress difference remaining on the front and back surfaces in the thickness direction of the vertical wall portion of the finally obtained hat-shaped molded product.

FIG. 6 shows the cases in which the press molding die 10 of the first embodiment, the press molding die 20 of the second embodiment, and the general die 300 are used, respectively. This figure shows the results of a simulation analysis of the amount of warpage due to springback that occurs in the vertical wall of the hat-shaped molded product that is finally obtained.

As shown in FIG. 6, as a result of analysis by the inventor of the present application, compared to the case where a general die 300 is used, the case where the press molding die 10 of the first embodiment is used, and the case where the press molding die 10 of the first embodiment is used, It was confirmed that when the press molding die 20 of the embodiment was used, it was possible to reduce the amount of warpage due to springback occurring in the vertical wall portion of the hat-shaped molded product finally obtained.

[Modified example]
Although the first and second embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention.
For example, it is also possible to adopt the following modifications.

FIG. 7A is a diagram schematically showing the first die shoulder surface 34 provided between the first vertical wall surface 33 and the blank pressing surface 31 in the press molding die 30 in the first modification. . As shown in this figure, when focusing on points P1, P2, P3, P4, and P5 that exist on the first die shoulder surface 34, point P1 exists on a circle whose radius of curvature is R1, and point P2 exists on a circle whose radius of curvature is R1. Point P3 exists on a circle whose radius of curvature is R3, point P4 exists on a circle whose radius of curvature is R4, and point P5 exists on a circle whose radius of curvature is R5. exists above. Here, R1=R2=R3=R4=R5.

The first curvature ρ(1) corresponding to point P1 is obtained as the reciprocal of the radius of curvature R1 (1/R1), and the second curvature ρ(2) corresponding to point P2 is obtained as the reciprocal of the radius of curvature R2 (1/R1). R2), the third curvature ρ(3) corresponding to point P3 is obtained as the reciprocal of the radius of curvature R3 (1/R3), and the fourth curvature ρ(4) corresponding to point P4 is the radius of curvature The fifth curvature ρ(5) corresponding to the point P5 is obtained as the reciprocal of the radius of curvature R5 (1/R5). The signs of curvature ρ(1), curvature ρ(3), and curvature ρ(5) are “positive,” and the signs of curvature ρ(2) and curvature ρ(4) are “negative.”

Here, all values of ρ(1) to ρ(5) are the same, but if we focus on the second curvature ρ(2) with a "negative" sign, we can see that the curvature ρ(1) and the curvature ρ( 3) all have "positive" signs, so the conditions ρ(2) < ρ(1) and ρ(2) < ρ(3) are satisfied, and in the first modification The first die shoulder surface 34 provided in the press molding die 30 satisfies the condition that there is at least one s-th curvature ρ(s) that satisfies the above relational expression (1).

FIG. 7(b) is a diagram schematically showing a first die shoulder surface 44 provided between the first vertical wall surface 43 and the blank pressing surface 41 in the press molding die 40 in the second modification. . As shown in this figure, when focusing on points P1, P2, and P3 that exist on the first die shoulder surface 44, point P1 exists on a circle (not shown) with a radius of curvature of R1 (=0), and point P2 exists on a circle (not shown) whose radius of curvature is R2 (=0), and point P3 exists on a circle (not shown) whose radius of curvature is R3 (=0). Here, R1=R2=R3=0.

The first curvature ρ(1) corresponding to point P1 is obtained as the reciprocal of the radius of curvature R1 (1/R1=1/0=+∞), and the second curvature ρ(2) corresponding to point P2 is the curvature The third curvature ρ (3) corresponding to point P3 is obtained as the reciprocal of the radius R2 (1/R2 = 1/0 = -∞), and the third curvature ρ (3) corresponding to the point P3 is the reciprocal of the radius of curvature R3 (1/R3 = 1/0 = +∞ ) is obtained as The signs of the curvature ρ(1) and the curvature ρ(3) are “positive,” and the signs of the curvature ρ(2) are “negative.”

Here, all values of ρ(1) to ρ(3) are the same, but if we focus on the second curvature ρ(2) with a "negative" sign, we can see that the curvature ρ(1) and the curvature ρ( 3) all have "positive" signs, so the conditions ρ(2) < ρ(1) and ρ(2) < ρ(3) are satisfied, and in the second modification The first die shoulder surface 44 provided in the press molding die 40 satisfies the condition that there is at least one s-th curvature ρ(s) that satisfies the above relational expression (1).

FIG. 8(a) schematically shows a press molding die 50 in a third modification. This press molding die 50 is a die used to manufacture a substantially L-shaped molded product 110 as shown in FIG. In this mold, only the vertical wall surface 53 exists, and the first vertical wall surface 53 and the blank pressing surface 51 are connected by a first die shoulder surface 54 having n curvatures. The shape of the first die shoulder surface 54 may be the same as the first die shoulder surface of any one of the first embodiment, the second embodiment, the first modification, and the second modification.

10, 20, 30, 40, 50...Mold for press molding 11, 21, 31, 41, 51...Blank pressing surface (end surface)
12, 22... Recessed portion 13, 23, 33, 43, 53... First vertical wall surface 14, 24, 34, 44, 54... First die shoulder surface 15, 25... Second vertical wall surface 16, 26... Second die shoulder surface 60 , 70... Press molding device 100, 110... Molded product 200... Metal plate (blank)
400...Blank holder 500...Punch

Claims (3)

an end face provided on one side in the height direction so as to intersect with the height direction, and a recess provided so as to be recessed from the end face to the other side in the height direction and extend in the length direction; A press molding die having:
A first vertical wall surface extending in the height direction exists on one side in the width direction as a surface forming an outline of the recess, and the first vertical wall surface and the end surface are connected by a first die shoulder surface having n curvatures. has been
When the curvatures are numbered in order from the first vertical wall surface toward the end surface on the first die shoulder surface, there is at least one s-th curvature ρ(s) that satisfies the following relational expression (1). A press molding die for hat-shaped molded products .
ρ(s)<ρ(s-1), and ρ(s)<ρ(s+1)...(1)
(However, n≧3, 2≦s≦n-1) A second vertical wall surface extending in the height direction exists on the other side in the width direction as a surface forming an outline of the recess, and the second vertical wall surface and the end surface are formed by a second die shoulder surface having n curvatures. connected and
When the curvatures are numbered in order from the second vertical wall surface toward the end surface on the second die shoulder surface, there is at least one s-th curvature ρ(s) that satisfies the relational expression (1). The press molding die according to claim 1 , characterized in that: A press molding die according to claim 1 or 2,
a blank holder having a blank support surface opposite to the end surface of the press molding die;
a punch having a protrusion that can be inserted into the recess of the press mold;
A press molding device characterized by comprising:

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