JP2023059228A - Manufacturing method of press-forming product, and press-forming metal mold - Google Patents

Abstract

To provide a manufacturing method of a press-forming product, and a press-forming metal mold in which cracks or winkles are suppressed during a molding process of an intermediate molded product so that occurrence of winkles at a punch shoulder R part or a top plate part is surely prevented when molding the intermediate molded product into a target shape.SOLUTION: A manufacturing method of a press-forming product according to the present invention is a manufacturing method which press-forms, by a die, a punch and a pad 18, a press-forming product including: a top plate part 3; a vertical wall part 7 which is continuous from the top plate part 3 through a punch shoulder R part 5; a flange part 11 which is continuous from the vertical wall part 7; and a bent part 13 which is bent in a concave shape when seen from a top view. The manufacturing method of a press-forming product comprises: an intermediate molded product molding step S1 molding an intermediate molded product 1 in which bend radius of the punch shoulder R part 5 in the bent part 13 is enlarged from a midship part of bending to an end side; and a target molded product molding step S2 remolding at least the punch shoulder R part 5 in which bend radius of the punch shoulder R part 5 is molded to be the same as the midship part of bending of the intermediate molded product 1 or less to obtain a target molded product 101.SELECTED DRAWING: Figure 1

Description

The present invention has a top plate portion, a vertical wall portion continuous from the top plate portion via a punch shoulder R portion, and a flange portion continuous from the vertical wall portion via a die shoulder R portion, and an upper surface The present invention relates to a method for manufacturing a press-formed product having a curved portion that is curved in a concave shape when viewed, and a press-molding die.

Press molding is a manufacturing method capable of manufacturing metal parts at low cost and in a short period of time, and is used in the manufacture of many automobile parts.
Moreover, in recent years, in order to achieve both the improvement of collision safety of automobiles and the weight reduction of automobile bodies, higher-strength metal plates have been used for automobile parts. The main problems in the press forming of high-strength metal sheets are the occurrence of cracks due to a decrease in ductility and the occurrence of wrinkles due to an increase in tensile strength.

For example, as shown in FIG. 12, in a press-formed product manufacturing method in which a press-formed product 101 in which a vertical wall portion 107 is concavely curved in a top view is formed into a target shape, the flange portion 111 at the curved portion 113 extends in the circumferential direction. Cracks are likely to occur when pulled.
In addition, as a reaction force, the top plate portion 103 and the punch shoulder R portion 105 in the curved portion 113 are deformed to contract in the circumferential direction, which easily causes wrinkles. This deformation is called stretch flange deformation. Therefore, it is important in the method of manufacturing a press-formed product having a shape such as the press-formed product 101 to suppress the occurrence of cracks and wrinkles in such stretch flanging deformation.

As a technique for suppressing cracks and wrinkles in a press-molded product that is concavely curved when viewed from above, for example, Patent Document 1 discloses the following technique. That is, it is a press forming method that increases the material movement toward the flange of the curved portion, which is likely to crack due to stretch flanging deformation, and reduces the material toward the top plate of the curved portion, which is likely to cause wrinkles.
This press molding method includes, as shown in FIG. When press-molding the intermediate molded product 1 (press-molded product 1) having a flange portion 11 continuous from the wall portion 7 and having a concavely curved portion when viewed from above, the bending radius of the punch shoulder R portion is set to devising. That is, by increasing the bending radius of the punch shoulder R portion 5 in the curved portion 13 from the central portion of the curve toward the end portion, the top of the curved end portion is bent as shown by the arrow in FIG. 3(a). The material is moved from the plate portion 3 toward the flange portion 11 at the central portion of the curve. Accordingly, cracks in the flange portion 11 of the curved portion 13 can be suppressed, and wrinkles in the top plate portion 3 and the punch shoulder R portion 5 on the flange portion side of the curved portion 13 can be suppressed.

Patent No. 6897840

However, the inventors have determined that the press-formed product shown in FIG. 3 is the intermediate formed product 1 and the press-formed product 101 shown in FIG. I noticed the following things by press molding as. In other words, the inventors have found that wrinkles are likely to occur in a portion having a large bending radius (punch shoulder R portion on the curved end side) in the punch shoulder R portion 5 of the intermediate molded product 1 .

On the curved end side, the bending radius of the punch shoulder R portion 5 of the intermediate molded product 1 (FIG. 2A) is the target bending radius of the punch shoulder R portion 105 of the press-formed product 101 (FIG. 12A). ). Then, when forming it into a target shape with a small bending radius, wrinkles tend to occur in the punch shoulder R portion 105 and the top plate portion 103 on the curved end side of the target molded product in some cases.

The present invention has been made to solve such problems, and suppresses cracks in the flange portion of the curved central portion and wrinkles in the top plate portion during the molding process of the intermediate molded product. In addition, a method for manufacturing a press-formed product that reliably prevents the generation of wrinkles in the punch shoulder R portion and the top plate portion on the curved end side when forming the intermediate formed product into a target shape, and the press-formed product. An object of the present invention is to provide a press molding die that enables the manufacturing method of

(1) A method for manufacturing a press-formed product according to the present invention includes a top plate portion, a vertical wall portion continuing from the top plate portion via a punch shoulder R portion, and a flange portion continuing from the vertical wall portion. A press-formed product manufacturing method for press-molding a press-formed product having a concavely curved portion in a top view with a die, a punch, and a pad,
an intermediate molded product forming step of molding an intermediate molded product in which the bending radius of the punch shoulder R portion in the curved portion is increased from the central portion of the curve toward the end portion;
A target molded product forming in which at least the punch shoulder R is reshaped to form a target molded product having a bending radius equal to or smaller than the bending radius of the central portion of the curve of the intermediate molded product. and
In the target molded article molding process,
The position of the punch shoulder R portion in the intermediate product includes the following position X, which is the most shifted toward the die, and is set to be the same as or closer to the position X than the following position Y, which is the most shifted toward the punch. Along with being
It is characterized in that the pad is pressed up to the boundary between the top plate portion and the punch shoulder R portion in the target molded product.
Position X: Position where the boundary between the top plate portion and the punch shoulder R portion in the intermediate molded product coincides with the boundary between the top plate portion and the punch shoulder R portion in the target molded product Position Y: Punch in the intermediate molded product A position where the amount of overhang of the arc of the shoulder R portion coincides with the amount of overhang of the arc of the punch shoulder R portion in the target molded product

(2) In addition, in the above (1), a metal plate having a tensile strength YS of 440 MPa class or higher is used as the blank.

(3) Further, a press-molding die according to the present invention enables the method of manufacturing a press-molded product described in (1) or (2) above.

According to the present invention, cracks in the flange portion of the curved central portion and wrinkles in the top plate portion are suppressed in the molding process of the intermediate molded product, and when molding the intermediate molded product into a target shape, It is possible to reliably prevent the punch shoulder R portion and the top plate portion from being wrinkled.

It is explanatory drawing of the press molding process in embodiment of this invention. It is explanatory drawing of the intermediate molded product in embodiment of this invention. FIG. 3 is an explanatory diagram of a mechanism by which wrinkles and cracks can be prevented in the intermediate molded product shown in FIG. 2; FIG. 3 is an explanatory diagram for explaining the reason why wrinkles are generated when the intermediate molded product shown in FIG. 2 is molded into a target molded product; FIG. 5 is a cross-sectional view taken along line EE′ of FIG. 4 and is an explanatory view of a portion that is not pressed by a pad; FIG. 10 is an explanatory diagram of a problem in the position of the pad pressing position and the position of the punch shoulder R portion of the intermediate molded product; FIG. 4 is an explanatory diagram of a position to be pressed by a pad, which is one of the devised points of the present invention; It is explanatory drawing of the position of a pad in embodiment, and arrangement|positioning of the punch shoulder R part of an intermediate molded product. FIG. 4 is an explanatory diagram of the position X of the punch shoulder R portion in the intermediate molded product defined in the embodiment; FIG. 4 is an explanatory diagram of the position Y of the punch shoulder R portion in the intermediate molded product defined in the embodiment; 5 is a graph showing the relationship between the amount of floating of a pad and the amount of misalignment of an intermediate molded product in Examples. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a shape of a target molded product in the present invention and a portion where wrinkles and cracks are likely to occur when the target molded product is press-molded.

Before describing the embodiments of the present invention, the circumstances leading to the present invention will be described.
<Circumstances leading to the invention>
In the method of manufacturing a press-formed product of the present invention, a press-formed product as disclosed in Patent Document 1 is used as an intermediate product, and this is formed into a target product (press-formed product 101 in FIG. 12).
First, an example of an intermediate molded product will be described with reference to FIGS.

As shown in FIG. 2, the intermediate molded product 1 includes a top plate portion 3, a vertical wall portion 7 continuing from the top plate portion 3 via a punch shoulder R portion 5, and a die shoulder R portion 9 extending from the vertical wall portion 7. It has a flange portion 11 that is continuous through. A curved portion 13 that is concavely curved when viewed from above, and a straight portion 15 that extends linearly from both ends of the curved portion 13 (broken lines in FIG. 2). The bending radius of 5 increases from the center of the curve toward the ends.

In the molding process of the intermediate molded product 1, the reason why both cracking of the flange portion 11 at the curved portion 13 of the intermediate molded product 1 and wrinkles of the top plate portion 3 and the punch shoulder R portion 5 can be suppressed. Description will be made based on FIG. 3 which schematically shows the movement of the material in . The broken lines in FIG. 3 indicate both ends of the curve (the boundary between the curved portion 13 and the straight portion 15).

In the punch shoulder R portion 5, the bending radius Rp,1 (FIG. 3(b)) at the curved end (AA' cross section) is equal to the bending radius Rp,2 at the curved center (BB' cross section). As shown in FIG. 3(c), the bending radius increases from the central portion of the curve toward the end portions. Therefore, as indicated by black arrows in FIG. 3(a), the material can easily move along the ridge line direction (perpendicular to the paper surface) from the end side of the curve of the punch shoulder R portion 5 toward the central portion, It is pulled toward the flange portion 11 side of the central portion of the curve.

On the other hand, since the curved center portion of the punch shoulder R portion 5 has a smaller bending radius than the curved end portion side, the material is less likely to move in the ridge line direction during the press forming process.
Therefore, in the press molding process of the intermediate molded product 1, the material can be moved from the top plate portion 3 at the curved end portion side toward the flange portion 11 at the curved center portion. As a result, cracking of the flange portion 11 at the curved portion 13 can be suppressed, and wrinkles at the top plate portion 3 and the punch shoulder R portion 5 of the curved portion 13 can be suppressed.

As described above, it was confirmed that wrinkles were generated in the punch shoulder R portion 105 on the curved end side during the molding process of the target molded product 101. The wrinkle generating mechanism will be described with reference to FIGS. explain.

In general, a pad used for press molding is press-molded while pressing a flat portion of the top plate portion excluding the punch shoulder R portion. For example, when molding the intermediate molded product 1, in order to prevent wrinkles from occurring in the top plate portion 3 of the intermediate molded product 1, the hatched portion in FIG. Carry out molding. Similarly, when forming the target molded product 101 , bending is performed while pressing the flat top plate portion 3 with the same pad 17 .

FIG. 4(b) shows the arrangement of the pads 17 when the target molded product 101 is molded. It is a part corresponding to the punch shoulder R part 5 on the part side. This part is the top plate portion 103 of the target molded product 101 , but cannot be pressed by the pad 17 because the intermediate molded product 1 is curved. That is, as shown in FIG. 5, the boundary K1 between the punch shoulder R portion 5 and the top plate portion 3 in the intermediate molded product 1 (dotted line) (hereinafter simply referred to as "boundary K1" or "boundary K1 in the intermediate molded product 1") ) and the boundary K2 between the punch shoulder R portion 105 and the top plate portion 103 in the target molded product 101 (solid line) (hereinafter simply referred to as “boundary K2” or “boundary K2 in the target molded product 101”) is , which cannot be pressed by the pad 17 .

When the target molded product 101 is molded without pressing the portion enclosed by the solid-line ellipse in FIG.
When forming the target product 101, a die and a punch having a small shoulder R are used to press-form the target product 101 with a punch shoulder R portion 105 having a small bending radius. At that time, first, the die shoulder R forming portion of the die comes into contact with the die side of the punch shoulder R portion having a large bending radius in the intermediate product 1, and forming is started. However, when the intermediate product 1 is sandwiched between the die shoulder R forming portion of the die and the punch shoulder R forming portion of the punch, the large punch shoulder R portion 5 of the intermediate formed product 1 is not pressed by the pad 17 . For this reason, it swells in the direction of the die bottom (in the direction opposite to the direction of press molding), and a surplus of material occurs between the die and the punch, so wrinkles are likely to occur.

In order to prevent wrinkles at the punch shoulder R portion 105 as described above from the mechanism of wrinkle generation in the molding process of the target molded product 101, first, it is necessary to press the relevant portion with a pad during molding. be.
That is, when molding the intermediate molded product 1 of FIG. 7(a) into the target molded product 101, as shown in FIG. A large pad 18 capable of
This point is one devised point in the present invention.

That is, when the intermediate molded product 1 is molded into the target molded product 101, the intermediate molded product is pressed by the large pad 18 to the boundary K2 of the target molded product 101 and molded.
However, for example, when a high-strength metal plate having a tensile strength of 440 MPa or more is molded into the target molded product 101, there are problems as follows. That is, when the intermediate product 1 is sandwiched between the die shoulder R forming portion of the die and the punch shoulder R forming portion of the punch during forming, the punch shoulder R portion 5 of the intermediate formed product 1 having a large bending radius is bent to a small radius. Bend along the punch shoulder R forming part of the punch. At this time, a large bending load that cannot be held by the pad acts in the direction of the bottom of the die (in the direction opposite to the press-forming direction), and the punch shoulder R portion 5 of the intermediate product 1 swells, causing the pad 18 to swell during bending. There was a case where it floated and wrinkled.

Further, in order to prevent the pad 18 from floating, the boundary K1 of the intermediate molded product 1 is moved further toward the die side than the boundary K2 of the target molded product 101 while keeping the position of the pad 18 pressed down to the boundary K2. It is conceivable to let it be (FIG. 6(b)).
However, if the punch shoulder R portion 5 of the intermediate molded product 1 having a large bending radius protrudes toward the die from the punch shoulder R portion 105 of the target molded product 101 having a small bending radius, the punch shoulder R portion 5 having a large bending radius is difficult to press with the pad 18, and wrinkles are likely to occur.

Therefore, as shown in FIG. 8, when forming the metal plate into the target shape, the position of the pad 18 is fixed at the position of the boundary K2, and the boundary K1 of the intermediate molded product 1 (dotted line) is aligned with the boundary K2. It has been found that by shifting a predetermined distance toward the punch side from the aligned state, it is possible to prevent the pad 18 from floating and wrinkles to be prevented.
The present invention is based on this knowledge and the above points of ingenuity. Specific embodiments will be described below.

<Embodiment>
The method for manufacturing a press-formed product according to the present embodiment comprises: top plate portion 103; vertical wall portion 107 continuous from top plate portion 103 via punch shoulder R portion 105; A press-formed product (see FIG. 12) having a flange portion 111 continuous via 109 and having a concavely curved portion 113 when viewed from above is press-formed with a die, a punch, and a pad 18. manufacturing method. Then, an intermediate molded product forming step S1 for molding an intermediate molded product 1 (see FIG. 2) in which the bending radius of the punch shoulder R portion 5 in the curved portion 13 is increased from the center portion of the curve toward the end portion side, and at least The punch shoulder R portion 5 is reshaped to form a target molded product 101 having a bending radius equal to or smaller than the bending radius of the central portion of the curve of the intermediate molded product 1. It has a molding step S2 (see FIG. 1).

In the target molded product molding step S2, the boundary K1 between the punch shoulder R portion 5 and the top plate portion 3 in the intermediate molded product 1 includes the position X (FIG. 9) that is most deviated toward the die side defined below. is set to be the same as or closer to the position X side than the position Y (FIG. 10) which is most shifted toward the punch side defined in . In addition, it is characterized in that the pad 18 presses up to the boundary K2 between the top plate portion 103 and the punch shoulder R portion 105 in the target molded product 101 for molding.

<Definition of position X and position Y>
As shown in FIG. 9, the position X is the position where the boundary K1 on the intermediate molded product 1 (dotted line) coincides with the boundary K2 on the target molded product 101 (solid line).
The reason why the position X is set to the position most deviated toward the die is as follows. If the boundary K1 in the intermediate molded product 1 is shifted further toward the die side than the position X, the wrinkles can be sufficiently suppressed by the pad 18 in the molding process of the target molded product 101, as shown in FIG. 6(b). Gone. As a result, when sandwiched between the die shoulder R forming portion of the die and the punch shoulder R forming portion of the punch, the intermediate formed product 1 rises and wrinkles occur. The range indicated by the black arrow in

As shown in FIG. 10, the position Y is the amount by which the arc of the punch shoulder R portion 5 in the intermediate molded product 1 (dotted line) protrudes toward the die side is equal to the arc of the punch shoulder R portion 105 in the target molded product 101 (solid line). This is the position that coincides with the amount of protrusion toward the die side of the . That is, as shown in FIG. 10, a point P closest to the die of the arc (dotted line) of the punch shoulder R portion 5 in the intermediate molded product 1 and the point P closest to the arc (solid line) of the punch shoulder R portion 105 in the target molded product 101 A point Q on the die side is a position on the same vertical line.

The reason why the position Y is set to be the most shifted position toward the punch is as follows. If the die-side extreme end of the arc of the punch shoulder R portion 5 of the intermediate molded product 1 is positioned closer to the punch side than the die-side extreme end of the arc of the punch shoulder R portion 105 of the target molded product 101, the intermediate molded product The vertical wall position of No. 1 is on the punch side (right side of the paper surface) from the vertical wall position of the target molded product 101 . As a result, even the vertical walls of the intermediate molded product 1 are molded into the target molded product 101, which is contrary to the intention of the present application. Therefore, the position of the intermediate molded product 1 (dotted line) was set to the area indicated by the black arrow in FIG.
The vertical wall portion 7 of the intermediate molded product 1 of the present application does not need to be parallel to the vertical wall portion 107 of the target molded product 101, and the angle formed by the top plate portion 3 and the vertical wall portion 7 of the intermediate molded product 1 is , may be different from the angle formed by the top plate portion 103 and the vertical wall portion 107 of the target molded product 101 (see FIG. 8).

In the target molded product molding step S2, if the punch shoulder R portion 5 of the intermediate molded product 1 is arranged as described above, the pad 18 can sufficiently press the vicinity of the small punch shoulder R portion 5 of the target molded product 101 to be molded. becomes possible. As a result, the rise of the punch shoulder R portion 5 of the intermediate molded product 1 toward the die bottom can be suppressed to prevent wrinkles.
Further, the die side of the large punch shoulder R portion 5 of the intermediate product 1 has an angle close to the vertical wall portion 7 as shown in FIG. I never get excited. As a result, the die side of the punch shoulder R portion 5 having a large bending radius of the intermediate product 1 is formed into the vertical wall portion 7 . Further, as shown in FIG. 10, the punch side of the intermediate product 1 is formed on the top plate portion 103 of the target product 101 while being pressed by the pad 18 up to the position of K2. Even if pressing progresses, wrinkles can be prevented.

At this time, part of the punch shoulder R portion 5 of the intermediate molded product 1 is remolded into the punch shoulder R portion 105 and the vertical wall portion 107 . Therefore, the cross-sectional line lengths of the punch shoulder R portion 5 and the vertical wall portion 7 in the intermediate molded product 1 are different between the position X in FIG. 9 and the position Y in FIG. Therefore, in order to obtain the cross-sectional line length of the target molded product, it is preferable to correct the vertical wall portion 7 of the intermediate molded product 1 in anticipation of this.

In the present invention, there are no particular restrictions on the material, strength, or part shape of the metal plate, but the effect is greater for metal plates that are more likely to wrinkle during press molding. For example, it is highly effective for a metal plate with a high tensile strength TS where internal stress increases during press working, and a thin metal plate that tends to buckle when a compressive stress is applied. Specifically, it is preferable to target a metal plate having a tensile strength TS of 440 MPa or higher or a metal plate having a thickness of 0.5 mm or more and 3.6 mm or less from the point of effect.

In addition, since a metal sheet having a tensile strength TS of less than 440 MPa class has high ductility, cracking due to stretch flanging deformation is less likely to occur, and the advantage of using the present invention is small. However, if the shape of the part is difficult to press-form, it is preferable to use the present invention even if the metal plate has a tensile strength TS of less than 440 MPa class.
Although there is no particular upper limit for the tensile strength TS, since metal plates exceeding 1600 MPa class have poor ductility, cracks are likely to occur at the punch shoulder R portions 5 and 105 and the die shoulder R portions 9 and 109, making press forming difficult. become.

The method for manufacturing a press-formed product according to the embodiment of the present invention is intended for a press-formed product having straight portions 15 extending from both curved ends of a curved portion 13, as shown in FIG. It was something. However, the present invention is not limited to this, and the press-formed product having only the curved portion 13 or the press-formed product having the straight portion 15 extending only from one end of the curve may be manufactured. with or without

Further, in the above description, the bending radius of the punch shoulder R portion 5 in the intermediate molded product 1 was made to increase from the center of the curve toward both ends. , may be increased toward one of the ends.
Further, according to the method for producing a press-formed product according to the present invention, in an automobile part having an L-shaped, T-shaped, Y-shaped, or S-shaped portion that is curved in a top view, a metal plate due to stretch flange deformation wrinkles of the top plate portion 3 can be prevented. As a specific example, the present invention is preferable when molding an A pillar lower having an L-shaped part, a B pillar having a T-shaped part, a rear side member having an S-shaped part, etc. Applicable.

Since concrete press molding was performed about the effect by the manufacturing method of the press-molded product which concerns on this invention, it demonstrates below.
In the press forming, two types of steel plates having the mechanical properties shown in Table 1 are used as metal plates, and the target formed product 101 (FIG. 12) is press formed from the intermediate formed product 1 (FIG. 2) shown in the above-described embodiment. Form molding was carried out in both the intermediate molded article molding process and the target molded article molding process. The pressing load of the pads 17 and 18 was 60 kN in both steps, and the press stroke was 80 mm. At the press bottom dead center of each process, a load of 6000 kN was applied to the entire part including the top plate surface.

The radius of curvature of the curved portion 113 at the height center of the vertical wall portion 107 of each press-molded product was 153 mm.
Further, the pads of Conventional Examples 1 and 2 and Comparative Examples 1 and 4 are the pads 17 up to the boundary K1 shown in FIGS. Pads 13 to 13 are pads 18 up to the boundary K2 shown in FIGS. 7B and 8 .

The bending radius of the intermediate molded product 1 at the punch shoulder ends of the curved portions 13 and 113 formed by press forming steel sheet G (980 MPa class) was set to 10 mm, and the bending radius of the target molded product 101 was set to 5 mm. The acute angle from the top plate portion 3 of the intermediate molded product 1 to the vertical wall portion 7 is 90 degrees, and the acute angle from the top plate portion 103 to the vertical wall portion 107 of the target molded product 101 is 90 degrees. Furthermore, the bending radius of the die shoulder R portions 9 and 109 is 6 mm for both the intermediate molded product 1 and the target molded product 101, the vertical wall height of the vertical wall portions 7 and 107 in the press forming direction is 60 mm, and the flange portions 11 and 111 The width was 30 mm at the center of the curve and 25 mm at the edge of the curve.

In addition, the bending radius of the intermediate molded product 1 at the punch shoulder ends of the curved portions 13 and 113 formed by press forming the steel plate H (1470 MPa class) is set to 20 mm, the bending radius of the target molded product 101 is set to 6 mm, and the top of the intermediate molded product 1 The acute angle from the plate portion 3 to the vertical wall portion 7 is 60 degrees, and the acute angle from the top plate portion 103 to the vertical wall portion 107 of the target molded product 101 is 80 degrees. The bending radius of the die shoulder R portions 9 and 109 is set to 6 mm for both the intermediate molded product 1 and the target molded product 101. Same as for G.

The curved end portion of the target molded product 101 after press molding was visually observed, and wrinkles extending from the punch shoulder R portion 105 of the curved end portion to the top plate portion 103 and cracking of the flange portion 111 were determined. When the wrinkles were conspicuous, the wrinkles were marked as ×, when the wrinkles were visually identifiable as Δ, when the wrinkles were identifiable but small enough to be acceptable in terms of part performance, ◯, and when they were not visually identifiable as ⊚. When the flange portion 111 at the center of the curve was cracked, it was evaluated as x, and when it was not cracked, it was evaluated as ○.
Table 2 shows the results.

Conventional Example 1, Comparative Examples 1 to 3, and Examples 1 to 6 are the results of press forming steel sheet G (980 MPa class).
In Conventional Example 1, the punch shoulder R portion 105 has a small bending radius of 5 mm in both the curved central portion and the curved end portion, and there was a problem that both conspicuous wrinkles and cracks occurred.
In Comparative Example 1, the punch shoulder R at the curved end of the intermediate molded product 1 was bent with a large bending radius of 10 mm, and a pad 17 (Fig. 4(b)) was used to bend the punch shoulder R at the curved end of the intermediate molded product 1. This is the case where the positional deviation amount of the intermediate molded product is set to 0.0 mm without pressing the part. In this case, wrinkles were visually confirmed, and no cracks occurred in the flange portion 11 .
In Comparative Example 2, the punch shoulder R portion of the curved end portion of the intermediate molded product 1 was bent with a large bending radius of 10 mm and a pad 18 (Fig. 7(b)) was used to bend the punch shoulder R portion of the curved end portion of the intermediate molded product 1. is pressed to set the positional deviation of the intermediate molded product to -1.0 mm (121.0 mm on the die side). In this case, wrinkles were visually confirmed, but no cracks occurred in the flange portion 111 .
Here, the amount of positional deviation of the intermediate molded product is the starting point of the punch shoulder R portion in the target molded product 101 and the intermediate molded product 1 (borders K1 and K2 between the punch shoulder R portions 5 and 105 and the top plate portions 3 and 103). 9) is defined as 0 (originating point), + (plus) when the boundary K1 of the intermediate molded product 1 is on the punch side, and - (minus) when it is on the die side.

In Examples 1 to 4, the punch shoulder R portion 5 of the intermediate molded product 1 has a large bending radius of 10 mm, and the pad 18 is used to press the punch shoulder R portion at the curved end of the intermediate molded product 1, thereby bending the intermediate molded product. This is the case where the amount of positional deviation is 0.0 mm to 3.0 mm (punch side). In Example 1, the boundary K1 between the punch shoulder R portion 5 at the curved end of the intermediate molded product 1 and the top plate portion 3 is the boundary between the punch shoulder R portion 105 at the curved end of the target molded product 101 and the top plate portion 103. This is the case when it matches the boundary K2. In these Examples 1 to 4, although wrinkles were confirmed, they were small enough to be permissible in terms of part performance, and the flange portion 111 was not cracked, which was good.

Further, in Examples 5 and 6, the punch shoulder R portion 5 of the intermediate molded product 1 has a large bending radius of 10 mm, and the pad 18 is used to press the punch shoulder R portion at the curved end of the intermediate molded product 1, so that the intermediate molding is performed. This is the case where the amount of product positional deviation is 4.0 mm and 5.0 mm, respectively. In Example 5, the die-side extreme end of the arc of the punch shoulder R 5 at the curved end of the intermediate molded product 1 and the die side of the arc of the punch shoulder R 105 at the curved end of the target molded product 101 This is the case where the extreme ends match (see FIG. 10). In Examples 5 and 6, wrinkles could not be visually confirmed, and cracks did not occur in the flange portion 111, which was remarkably good.

On the other hand, in Comparative Example 3, the punch shoulder R portion 5 of the intermediate molded product 1 has a large bending radius of 10 mm, and the pad 18 is used to press the punch shoulder R portion at the curved end of the intermediate molded product 1, thereby This is the case where the amount of misalignment of the molded product is 6.0 mm. In this case, the outermost end of the arc of the punch shoulder R 5 at the curved end of the intermediate molded product 1 is closer to the punch than the outermost end of the arc of the punch shoulder R 105 of the curved end of the target molded product 101 . It entered too much, and the punch was in a state of forming a vertical wall, and it was out of judgment.

Next, Conventional Example 2, Comparative Examples 4 and 5, and Examples 7 to 13 are the results of press forming steel plate H (1470 MPa class).
In Conventional Example 2, the punch shoulder R portion 5 has a small bending radius of 6 mm in both the curved center portion and the curved end portion, and there was a problem that conspicuous wrinkles and cracks occurred.
In Comparative Example 4, the punch shoulder R portion 5 at the curved end of the intermediate molded product 1 was bent with a large bending radius of 20 mm, and a pad 17 (Fig. 4(b)) was used to bend the punch shoulder R at the curved end of the intermediate molded product 1. This is the case where the positional deviation amount of the intermediate molded product is set to 0.0 mm without pressing the part. In this case, wrinkles were visually confirmed, and no cracks occurred in the flange portion 11 .
In Comparative Example 5, the punch shoulder R portion 5 at the curved end of the intermediate molded product 1 has a large bending radius of 20 mm, and a pad 18 (FIG. 7(b)) is used to bend the punch shoulder R at the curved end of the intermediate molded product 1. This is the case where the positional deviation amount of the intermediate molded product is set to -1.0 mm by pressing the part. In this case, wrinkles were visually confirmed, but no cracks occurred in the flange portion 111 .

In Examples 7 to 10, the punch shoulder R portion 5 has a large bending radius of 20 mm, and the positional deviation of the intermediate molded product is 0.0 mm to 6.3 mm. Further, in Example 7, the boundary K1 between the punch shoulder R portion 5 at the curved end of the intermediate molded product 1 and the top plate portion 3 is the boundary between the punch shoulder R portion 105 at the curved end of the target molded product 101 and the top plate portion 103. This is the case when it coincides with the boundary K2 (see FIG. 9). In these Examples 7 to 10, although wrinkles were confirmed, they were small enough to be permissible in terms of part performance, and the flange portion 111 was not cracked, which was good.

Examples 11 to 13 are cases in which the punch shoulder R portion 5 has a large bending radius of 20 mm and the positional deviation amount of the intermediate molded product is 8.4 mm to 11.4 mm. In Example 13, the die-side extreme end of the arc of the punch shoulder R 5 at the curved end of the intermediate molded product 1 and the arc of the punch shoulders R 5 and 105 at the curved end of the target molded product 101 are on the die side. This is the case where the extreme ends match (see FIG. 10). In Examples 11 and 13, wrinkles could not be visually confirmed, and cracks did not occur in the flange portions 11 and 111, so they were remarkably good.

Furthermore, when the pressing load of the pad 18 is 60 kN, the floating amount of the pad 18 in the above Examples 1 to 6 and Examples 7 to 13 is obtained from the FEM calculation for molding the intermediate molded product 1 into the target molded product 101. are shown in FIG. The values in parentheses ( ) indicate misalignment of the intermediate molded product.
Example 5 (4.0 mm), Example 6 (5.0 mm), Example 11 (8.4 mm), Example 12 (10.5 mm) and Example 13 (11.4 mm) wrinkles can not be visually confirmed when remarkably good (⊚) indicates that the pad 17 was not lifted at all.

As described above, according to the method for manufacturing a press-formed product according to the present invention, cracking of the flange portion 111 at the curved center portion of the target formed product 101 is suppressed, and wrinkles of the top plate portion 103 and the punch shoulder R portion 105 at the curved end portion are suppressed. can be suppressed.

<Intermediate molded product>
1 Intermediate molded product (press molded product)
3 top plate portion 5 punch shoulder R portion 7 vertical wall portion 9 die shoulder R portion 11 flange portion 13 curved portion 15 straight portion 17 pad 18 pad <target molded product>
101 target molded product (press molded product)
103 Top plate portion 105 Punch shoulder R portion 107 Vertical wall portion 109 Die shoulder R portion 111 Flange portion 113 Curved portion 115 Straight portion K1 Boundary between top plate portion and punch shoulder R portion in intermediate molded product K2 Top plate in target molded product Boundary between part and punch shoulder R part

Claims (3)

It has a top plate portion, a vertical wall portion continuous from the top plate portion via a punch shoulder R portion, and a flange portion continuous from the vertical wall portion. A method for producing a press-formed product by press-forming the press-formed product with a die, a punch, and a pad,
an intermediate molded product forming step of molding an intermediate molded product in which the bending radius of the punch shoulder R portion in the curved portion is increased from the central portion of the curve toward the end portion;
A target molded product forming in which at least the punch shoulder R is reshaped to form a target molded product having a bending radius equal to or smaller than the bending radius of the central portion of the curve of the intermediate molded product. and
In the target molded article molding process,
The position of the punch shoulder R portion in the intermediate product includes the following position X, which is the most shifted toward the die, and is set to be the same as or closer to the position X than the following position Y, which is the most shifted toward the punch. Along with being
A method of manufacturing a press-formed product, wherein the target formed product is formed while being held by a pad up to a boundary between the top plate portion and the punch shoulder R portion.
Position X: Position where the boundary between the top plate portion and the punch shoulder R portion in the intermediate molded product coincides with the boundary between the top plate portion and the punch shoulder R portion in the target molded product Position Y: Punch in the intermediate molded product A position where the amount of overhang of the arc of the shoulder R portion coincides with the amount of overhang of the arc of the punch shoulder R portion in the target molded product 2. The method of manufacturing a press-formed product according to claim 1, wherein a metal plate having a tensile strength YS of 440 MPa class or higher is used as the blank. A press-molding die that enables the method of manufacturing a press-molded product according to claim 1 or 2.

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