JP2022025205A - Press molding method and press molding metal mold - Google Patents

Abstract

To provide a press molding method and a press molding metal mold which can simultaneously prevent cracking of both of a tip of a vertical wall part formed at a central part of a branch and a bent back part in both side parts of the branch when molding a press molded product comprising a top plate part which has a bifurcated shape in a plan view and the vertical wall part continuous with the top plate part.SOLUTION: A press molding method comprises: an overhang molding process S1 in which a top plate part 1, an intermediate vertical wall part 9 on a base end side of the vertical wall part 3, a bent part 11, and a shelf part 13 are overhang-molded; a trimming process S3 in which an unnecessary part is removed from the shelf part 13, and a flange part 25 is formed; and a restriking process S5 in which the bent part 11 is bent back, and the intermediate vertical wall part 9 and the vertical wall part 3 comprising a part corresponding to the flange part 25 are molded. In the overhang molding process S1, molding is performed so that a bend radius of a central part of a branch in the bent part 11 becomes smaller than a bend radius of parts on both sides in a bending ridge line direction of the central part of the branch (branch both sides).SELECTED DRAWING: Figure 1

Description

The present invention relates to a press molding method for press molding a member such as an automobile part from a metal base plate and a press molding die, and in particular, a top plate portion having a bifurcated shape in a plan view, such as a lower arm, and the same. The present invention relates to a press molding method and a press molding die of a press-molded product having a continuous vertical wall portion on a top plate portion.

Some press-molded products have a top plate portion having a bifurcated shape in a plan view and a vertical wall portion continuous with the top plate portion, such as a lower arm which is an automobile undercarriage component. .. An example of such a press-molded product will be described with reference to FIG.
The press-molded product 5 shown in FIG. 6 has a top plate portion 1 having a bifurcated shape in a plan view, and a vertical wall portion 3 continuous with the top plate portion 1. Hereinafter, the bifurcated portion of the press-molded product 1 is referred to as a bifurcated portion 23.

When the vertical wall portion 3 is formed on the top plate portion 1 having a bifurcated shape as shown in FIG. 6, the vertical wall portion 3 formed on the bent portion (central portion of the branch portion) of the top plate portion 1 is elongated. Since the flange is deformed, the tip of the vertical wall portion 3 (the o portion surrounded by the broken line circle in the figure) is likely to be stretched and the flange is cracked.

In order to avoid the above-mentioned stretch flange cracking, such a press-molded product 5 is generally manufactured by a plurality of steps as described below.
First, an intermediate vertical wall that is continuous with the top plate portion 1 and the top plate portion 1 and is the base end side of the vertical wall portion 3 as shown in FIG. 7 by foam molding or the like in which a blank (metal plate) is pressed with a pad. An intermediate molded product 7 having a portion 9, a bent portion 11 continuous with the intermediate vertical wall portion 9, and a shelf portion 13 continuous with the bent portion 11 is overhanged (overhang molding step).

Next, as shown in FIG. 8, the panel is trimmed along a predetermined trim line, unnecessary portions (parts shown by diagonal lines in the figure) are removed from the shelf portion 13 of the intermediate molded product 7, and the flange portion 25 is removed. Form (trim process). Then, by bending back the bent portion 11 and erecting the flange portion 25 (restrictive), a vertical wall portion 3 composed of an intermediate vertical wall portion 9 and a portion corresponding to the flange portion 25 is formed (restrictive process). The press-molded product 5 shown in 6 is manufactured. In FIG. 6, the portion shown in gray in the figure is a portion corresponding to the bent portion 11 bent back in the rest-like step.

In the method described above, the amount of deformation during the subsequent rest-like step is reduced by interposing the intermediate molded product 7 molded by overhang molding. Further, since the intermediate molded product 7 is provided with a surplus portion (a portion to be removed in the trim step), a portion corresponding to the o portion shown in FIG. 6 during overhang molding (a portion indicated by a broken line circle in the state of FIG. 7). Since the material flow is suppressed, it is possible to suppress the stretched flange cracking that occurs in the o portion during the restoration process.
As such a press molding method, Patent Document 1 discloses an example in which overhang molding and trimming are carried out in the same process.

JP-A-2017-21766898

The inventors conducted molding analysis and press molding experiments by the finite element method for press-molded products such as lower arms having various shapes, and depending on the shape of the branch portion 23, the vertical wall formed in the central portion of the branch portion. Not only the tip (o part) of the part 3, but also the part bent back in the rest-like process in the vicinity of the central part of the branch part (a part and b part surrounded by the broken line circle in the figure, and the central part of the branch part in the bending ridge line direction). It was clarified that cracks also occur during molding in the parts on both sides of the above, hereinafter simply referred to as "both sides of the branch"). The reason why the cracks occur in the a part and the b part will be described with reference to FIGS. 6 and 9.

9 (a) is a cross-sectional view taken along the line A'-A'of the intermediate molded product 7 shown in FIG. 8, and FIG. 9 (b) is a cross-sectional view taken along the line AA of the press-molded product 5 shown in FIG. be. The cross-sectional view taken along the line A'-A'and the cross-sectional view taken along the line AA show a cross-sectional view of a portion corresponding to the portion a in the intermediate molded product 7 and the press-molded product 5.
The intermediate vertical wall portion 9, the bent portion 11, and the flange portion 25 (see FIG. 9A) formed by the overhang forming step and the trim step are formed by bending back the bent portion 11 by the rest-like step, so that FIG. 9 (see FIG. 9A) As shown in b), it becomes the vertical wall portion 3. At this time, work hardening occurs in the portion corresponding to the bent portion 11 that has been bent back, so that the plate thickness of the portion indicated by the arrow in the figure decreases.
Further, since the o portion where the material shortage is likely to occur due to the deformation of the stretch flange is in the vicinity (see FIG. 6), the material flow from the a portion to the o portion is generated. Due to both the reduction of the plate thickness and the action of the material flow, cracks occur in the a part. Further, for the same reason, the b portion is also cracked.

In order to suppress cracks that occur in parts a and b as described above, in order to reduce work hardening, the bending radius of the bent part 11 of the intermediate molded product 7 is increased to increase the bending radius in the overhang molding process. The amount of deformation may be reduced, but if the amount of deformation in the overhang molding step is reduced, the amount of deformation in the subsequent restorike step becomes large, and cracks are likely to occur in the o portion.
As described above, in the conventional technique, the tip (o portion) of the vertical wall portion 3 formed in the central portion of the branch portion and the bent back portions (a portion and b portion) on both side portions of the branch portion are prevented from cracking at the same time. There was a problem that it was difficult to do.

The present invention has been made to solve such a problem, and is a press provided with a top plate portion having a bifurcated shape in a plan view, such as a lower arm, and a vertical wall portion continuous with the top plate portion. When molding a molded product, a press molding method and a press molding die that can prevent cracking at the same time for both the tip of the vertical wall formed in the center of the branch and the bent back portion on both sides of the branch are used. The purpose is to provide.

(1) The press-molding method according to the present invention is to press-mold a press-molded product having a top plate portion having a bifurcated shape in a plan view and a vertical wall portion continuous with the top plate portion. Then, with the metal plate pressed against the punch with a pad, the top plate portion, the intermediate vertical wall portion that is continuous with the top plate portion and is the base end side of the vertical wall portion, and the intermediate vertical wall portion are continuous. An overhang molding step in which the punch and the die cooperate to overhang and form a bent portion and a shelf portion continuous with the bent portion, and a trim step in which an unnecessary portion is removed from the shelf portion to form a flange portion. A wrist-like step of bending back the bent portion to form the vertical wall portion including the intermediate vertical wall portion and the portion corresponding to the flange portion is provided, and the overhang forming step is a branch portion in the bent portion. It is characterized in that the bending radius of the central portion is formed so as to be smaller than the bending radius of the portions on both sides in the bending ridge line direction of the central portion of the branch portion.

(2) The press-molding die according to the present invention is for realizing the press-molding method according to (1) above, and is continuous with the top plate portion and the vertical wall portion. From the intermediate vertical wall portion on the base end side of the above, a first mold for molding an intermediate molded product having a bent portion continuous with the intermediate vertical wall portion, and a shelf portion continuous with the bent portion, and the shelf portion. A second mold for forming a flange portion by removing unnecessary portions, and a third mold for forming the vertical wall portion including the intermediate vertical wall portion and a portion corresponding to the flange portion by bending back the bent portion. The first mold includes a punch having a top plate portion forming surface portion for forming the top plate portion, a pad arranged facing the punch and pressing a metal plate against the punch, and an intermediate vertical portion. It has an intermediate vertical wall portion forming surface portion for forming a wall portion, a die shoulder portion for forming the bent portion, and a die having a shelf portion forming surface portion for forming the shelf portion, and the central portion of the branch portion in the die is formed. The die shoulder R to be formed is set smaller than the die shoulder R forming the portions on both sides in the bending ridge line direction of the branch center portion.

In the present invention, in the overhang molding step of molding an intermediate molded product, the bending radius of the central portion of the branch portion at the bent portion is formed to be smaller than the bending radius of both portions in the bending ridge line direction of the central portion of the branched portion. By doing so, it is possible to suppress the decrease in the plate thickness of the bent-back portion on both sides of the branch portion and the amount of deformation of the central portion of the branch portion during the retreating process. Therefore, the vertical wall portion formed in the central portion of the branch portion. It is possible to prevent cracking at the same time at both the tip of the portion and the bent back portion at both sides of the branch portion.

It is explanatory drawing of the press molding method which concerns on one Embodiment of this invention. It is explanatory drawing of the overhang molding process which concerns on one Embodiment of this invention, and the 1st mold used for this. FIG. 1A is a diagram showing a PP cross section and an OO cross section of the intermediate molded product in FIG. 1A, and is an explanatory diagram illustrating a difference in bending radius between a bent portion in the PP cross section and a bent portion in the OO cross section. Is. It is explanatory drawing of the trim process which concerns on one Embodiment of this invention, and the 2nd mold used for this. It is explanatory drawing of the rest like process which concerns on one Embodiment of this invention, and the 3rd mold used for this. It is explanatory drawing explaining the target shape which concerns on one Embodiment of this invention, and the problem which arises in the molding process of the target shape. It is explanatory drawing of the conventional press molding method (the 1). It is explanatory drawing of the conventional press molding method (the 2). It is explanatory drawing explaining the reason why crack occurs in the molding process of the target shape shown in FIG.

In the press molding method according to the present embodiment, a press-molded product 5 (see FIG. 6) having a top plate portion 1 having a bifurcated shape in a plan view and a vertical wall portion 3 continuous with the top plate portion 1 is provided. As shown in FIG. 1, an overhang molding step S1 for molding a metal plate into an intermediate molded product 7 and a trim step for removing unnecessary portions from the intermediate molded product 7 formed in the overhang molding step S1. It is provided with S3 and a restlike step S5 for molding the intermediate molded product 7 from which unnecessary portions have been removed in the trim step S3 into a target shape.
Hereinafter, each step will be described. In FIG. 1, the same parts as those in FIGS. 6 to 8 and the corresponding parts for explaining the target shape and the intermediate molded product 7 are designated by the same reference numerals.

<Overhang molding process>
The overhang molding step S1 is a step of molding the intermediate molded product 7 as shown in FIG. 1 (a), and the intermediate molded product 7 is continuous with the top plate portion 1 and the top plate portion 1 of the vertical wall portion 3. It has an intermediate vertical wall portion 9 on the base end side, a bent portion 11 continuous with the intermediate vertical wall portion 9, and a shelf portion 13 continuous with the bent portion 11.

In the overhang molding step S1 for molding such an intermediate molded product 7, as shown in FIG. 2, the punch 15 having the top plate portion forming surface portion 15a for forming the top plate portion 1 is arranged so as to face the punch 15. A pad 17 for pressing a metal plate against a punch 15, an intermediate vertical wall forming surface 19a for forming an intermediate vertical wall 9, a die shoulder 19b for forming a bent portion 11, and a shelf forming surface 19c for forming a shelf 13. This is done by the first mold 21 having the die 19 having.

FIG. 2A is an OO cross section which is a cross section of the central portion of the branch portion of the intermediate molded product 7 (see the enlarged view of FIG. 1A), and FIG. 2B is the bending ridge line direction of the bending portion 11. It is a figure which shows the state of the molding bottom dead center of the PP cross section (see the enlarged view of FIG. 1 (a)) which is the cross section of both side | branch portions in the above.
As can be seen by comparing FIGS. 2 (a) and 2 (b), with respect to the die shoulder portion 19b that forms the bent portion 11, the die shoulder _R1 (FIG. 2 (a)) at the center of the branch portion is on both sides of the branch portion. It is smaller than the die shoulder R ₂ (FIG. 2 (b)) of the portion, that is, R ₁ <R ₂ is set.
As shown in the enlarged view of FIG. 1 (a), the shape between the die shoulder R ₁ and the die shoulder R ₂ is such that R gradually changes in the bending ridge line direction (gradual change portion).

In the overhang forming step S1 using the first mold 21 as described above, the die 19 is initially positioned (not shown) with the metal plate held by the top plate forming surface portion 15a of the punch 15 and the pad 17. From the above, by lowering to the position of the bottom dead center shown in FIGS. 2 (a) and 2 (b), the top plate portion 1 and the intermediate portion which is continuous with the top plate portion 1 and becomes the base end side of the vertical wall portion 3. An intermediate molded product 7 having a vertical wall portion 9, a bent portion 11 continuous with the intermediate vertical wall portion 9, and a shelf portion 13 continuous with the bent portion 11 is molded.
Then, the bending radius of the bent portion 11 at the central portion of the branched portion of the intermediate molded product 7 is made smaller than the bending radius of the bent portion 11 at both side portions of the branched portion.
Further, between the bent portion 11 having a small bending radius at the center of the branch portion and the bent portion 11 having a large bending radius at both sides of the branch portion, the bending radius gradually expands from the center to both sides in the bending ridge line direction. Become a department.

In FIG. 3, the solid line shows the cross section of the central portion of the branch portion of the intermediate molded product 7 (OO cross section), and the broken line shows the cross section of both sides of the branch portion of the intermediate molded product 7 (PP cross section). In order to make it easy to understand the difference in the bending radius of the bent portion 11, both cross sections are shown superimposed.

As shown in FIG. 3, by reducing the bending radius of the bending portion 11 at the center of the branch portion (see the OO cross section) and increasing the bending radius of both sides of the branch portion (see the PP cross section), O The line length in the −O cross section (distance of the solid line from the X point to the Y point) is long, and the line length in the PP cross section (distance of the broken line from the X point to the Y point) is short. Therefore, in the overhang forming step S1, the amount of deformation of the central portion of the branch portion is larger than that of both side portions of the branch portion.
It should be noted that the points X and Y are arbitrary points common to both cross sections when both cross sections are overlapped.

In this way, the bending radius of the central portion of the branch portion in the bent portion 11 of the intermediate molded product 7 is made smaller than the bending radius of both sides of the branched portion, and the amount of deformation of the central portion of the branched portion in the overhang molding step S1 is reduced on both sides of the branched portion. The reason for making the portion larger than the portion will be described with reference to FIGS. 1 and 3.

In the press molding method in the present embodiment, the vertical wall portion 3 is formed in the branch portion 23 by the overhang molding step S1 and the restlike step S5. Therefore, if the amount of deformation in the overhang molding step S1 is large, the press forming method is performed. The amount of deformation in the minute list-like step S5 becomes small.
Therefore, by forming a large amount of deformation (large area) of the central portion of the branch portion at the time of molding the intermediate molded product 7, the deformation of the stretched flange during the restlike step S5 is alleviated, and the o portion shown in FIG. 6 is formed. Cracking is suppressed.

On the other hand, since the amount of deformation of the intermediate molded product 7 at the time of molding is kept small on both sides of the branch portion, the decrease in the plate thickness of the bent portion 11 can be suppressed. Further, as described above, since the elongation flange deformation generated in the o-part in the rest-like step S5 is also reduced, the material flow toward the o-part is also alleviated, and the cracking of the a-part shown in FIG. 6 is suppressed. To.
For the same reason, the cracking of the b portion shown in FIG. 6 is also suppressed.

<Trim process>
The trim step S3 is a step of removing unnecessary portions from the shelf portion 13 of the intermediate molded product 7 molded in the overhang molding step S1 to form the flange portion 25.

FIG. 4 is a diagram showing a state in the middle of trimming in the BB cross section of FIG. 1 (b).
As shown in FIG. 4, the trim step S3 is performed by a second mold 33 having an upper blade 27, a lower blade 29, and a plate retainer 31. The upper blade 27 and the lower blade 29 are for collaborating to remove unnecessary portions from the shelf portion 13 of the intermediate molded product 7, and each of them has a trim blade having a shape corresponding to the cutting line (trim line). (Not shown).

In the trim step S3, a part of the top plate portion 1 and the shelf portion 13 of the intermediate molded product 7 formed in the overhang molding step S1 is sandwiched between the lower blade 29 and the plate retainer 31, for example, the upper blade 27 is placed at the initial position. The flange portion 25 is formed by moving relatively downward from (not shown) and cutting off the unnecessary portion (the portion shown by the diagonal line in FIG. 1B) from the shelf portion 13.

<Restor-like process>
The wrist-like step S5 is a step of bending back the bent portion 11 of the intermediate molded product 7 from which the unnecessary portion was removed in the trim step S3 to form the vertical wall portion 3 and forming the vertical wall portion 3 into a target shape.

FIG. 5 is a diagram showing the state of the rest-like bottom dead center in the CC cross section of FIG. 1 (c).
The wrist-like step S5 is performed by a third mold 41 having a punch 35, a pad 37, and a die 39, as shown in FIG.
The punch 35 has a molding surface corresponding to the inner surface of the press-molded product 5, and grips the top plate portion 1 of the intermediate molded product 7 together with the pad 37. Further, the die 39 has a molding surface corresponding to the outer surface of the vertical wall portion 3 of the press-molded product 5, and bends back the bent portion 11 of the intermediate molded product 7 from which the unnecessary portion has been removed in the trim step S3. ..

In the rest-like step S5 using the third mold 41 as described above, the die 39 is initially positioned (not shown) with the top plate portion 1 of the intermediate molded product 7 being gripped by the punch 35 and the pad 37. Then, by lowering to the position of the bottom dead center shown in FIG. 5, the bent portion 11 is bent and stretched to erect the flange portion 25 to form the vertical wall portion 3, and the press-molded product 5 shown in FIG. 1 (c) is formed. Mold.

As described above, in the present embodiment, in the overhang molding step S1, the intermediate molded product 7 is molded so that the bending radius of the central portion of the branch portion in the bent portion 11 is smaller than the bending radius of both sides of the branched portion. After removing the unnecessary portion in the trim step S3 to form the flange portion 25, the bent portion 11 is bent back and the portion where the stretched flange is deformed is formed in the rest-like step S5.
As a result, in the central portion of the branch portion, the amount of deformation during the wrist-like step S5 is reduced and the elongation flange deformation is suppressed, so that cracking at the tip of the vertical wall portion 3 can be prevented.
Further, on both sides of the branch portion, the reduction in the plate thickness of the bend-back portion is suppressed, and the elongation flange deformation at the center portion of the branch portion is suppressed to alleviate the material flow, so that cracks generated in the bend-back portion occur. Can be prevented.

In the above description, an example in which press molding is carried out by dividing it into three steps has been described, but the present invention is not limited to this, and for example, trim blades are provided in the punch 15 and the die 19 in the overhang molding step S1, respectively. By forming the intermediate molded product 7 and removing unnecessary portions, the overhanging step S1 and the trimming step S3 may be performed in one step, and may be performed in two steps as a whole.

Further, the vertical wall portion 3 other than the branch portion 23 may be molded during the above-mentioned three steps, or may be molded in another step without any problem in carrying out the present invention. The same applies to the molding of the top plate portion 1.

In order to confirm the effect of the present invention, CAE analysis was performed on the press molding with the lower arm component as the target shape as shown in FIG.
The metal plate used as the material was a hot-rolled steel plate having a plate thickness of 2.3 mm and a tensile strength of 780 MPa class.
The press forming step was the three steps of the overhang forming step S1, the trim step S3, and the wrist-like step S5 described in the first embodiment.
Further, the bending radius of the bent portion (the portion formed by the punch shoulder) between the top plate portion 1 and the vertical wall portion 3 in the target shape is set to 7 mm.
Here, the bending radius is the radius of the central portion of the plate thickness with respect to the arc.

As a conventional press molding method, two types of press molding methods in which the bending radius of the bending portion 11 of the intermediate molded product 7 is the same in the central portion of the branch portion and both sides of the branch portion are analyzed. The bending radius of the bent portion 11 in the conventional example is 5 mm (conventional example 1) or 7 mm (conventional example 2) for both the central portion of the branched portion and both side portions of the branched portion.

Further, as a press molding method of the example of the present invention, an analysis was performed in which the bending radius of the central portion of the branch portion in the bent portion 11 of the intermediate molded product 7 was smaller than the bending radius of both sides of the branched portion. In the example of the invention, the bending radius of the bent portion 11 is 5 mm at the central portion of the branched portion and 7 mm at both sides of the branched portion (parts a and b in FIG. 6).
Table 1 shows the maximum plate thickness reduction rate of the a part, the b part, and the o part (see FIG. 6) at the bottom dead center of the restlike step S5 obtained by the CAE molding analysis.

According to the past findings of the inventors who prototyped lower arms of various shapes, in the case of a hot-rolled steel sheet with a plate thickness of 2.3 mm and a tensile strength of 780 MPa, cracks occur when the plate thickness reduction rate exceeds 20% in CAE forming analysis. Occur. Therefore, the molding limit at which cracks occur in this embodiment is set to a plate thickness reduction rate of 20%.

As shown in Table 1, in the case of Conventional Example 1, the plate thickness reduction rate of the o part is 20% or less of the molding limit, but the plate thickness reduction rate of the a part and the b part exceeds the molding limit of 20%. There is. Therefore, in the press molding method of Conventional Example 1, it was determined that cracks did not occur in the o part, but cracks occurred in the a part and the b part.

Further, in the case of Conventional Example 2, the plate thickness reduction rate of the a portion and the b portion is 20% or less of the molding limit, but the plate thickness reduction rate of the o portion exceeds the molding limit of 20%. Therefore, in the press molding method of Conventional Example 2, it was determined that cracks did not occur in the a part and the b part, but cracks occurred in the o part.

On the other hand, in the case of the invention example, the plate thickness reduction rate was 20% or less of the molding limit in all of the a part, the b part, and the o part, and it was determined that no cracking occurred at any place.
As described above, from the results of this embodiment, it was found that the tip of the vertical wall portion at the center of the branch portion of the press-molded product having a bifurcated shape such as the lower arm and the cracking at both sides of the branch portion can be prevented at the same time. rice field.

In the conventional example 1 of Table 1 above, the bending radius of the central portion (o portion) of the branch portion and both side portions (a portion and b portion) of the branch portion of the intermediate molded product 7 are the same, and the plate thickness of the central portion of the branch portion is reduced. This is an example in which the rate is within the molding limit range, but the plate thickness reduction rate on both sides of the branch portion exceeds the molding limit range.
Further, in the conventional example 2 of Table 1, the bending radius of the central portion of the branch portion and both sides of the branch portion of the intermediate molded product 7 is the same, the plate thickness reduction rate of the central portion of the branch portion exceeds the molding limit range, and both sides of the branch portion. This is an example in which the plate thickness reduction rate of the portion is within the molding limit range.
Then, from the conventional example 1, it can be seen that the bending radius at the central portion of the branch portion may be equal to or less than the value set in the conventional example 1, and from the conventional example 2, the bending radius at both sides of the branch portion is the conventional example. It can be seen that the value should be greater than or equal to the value set in 2.

From this, it can be seen that the bending radius of the central portion of the branch portion and the both sides of the branch portion may be set as follows.
That is, the bending radii of the central portion of the branch portion and both sides of the branch portion of the intermediate molded product 7 are made the same, and the values are variously changed to obtain the plate thickness reduction rate of the rest-like bottom dead center. And the example (A value) where the bending radius of both sides of the branch is the same, the plate thickness reduction rate of the central part of the branch is within the molding limit range, and the plate thickness reduction rate of both sides of the branch exceeds the molding limit. An example (B value) in which the plate thickness reduction rate at the center of the branch portion exceeds the molding limit range and the plate thickness reduction rate at both sides of the branch portion is within the molding limit is obtained in advance, and molding is performed at the center portion of the branch portion. The value is set to be equal to or less than the A value within the limit range, the value is set to be equal to or higher than the B value within the molding limit range at both sides of the branch portion, and the bending radius of the central portion of the branch portion is set smaller than the bending radius of both sides of the branch portion.

1 Top plate part 3 Vertical wall part 5 Press molded product 7 Intermediate molded product 9 Intermediate vertical wall part 11 Bending part 13 Shelf part 15 Punch 15a Top plate part Molded surface part 17 Pad 19 Die 19a Intermediate vertical wall part Molded surface part 19b Die shoulder part 19c Shelf part Molded surface part 21 1st mold 23 Branch part 25 Flange part 27 Upper blade 29 Lower blade 31 Plate holder 33 2nd mold 35 Punch 37 Pad 39 Die 41 3rd mold

Claims (2)

A press-molding method for press-molding a press-molded product having a top plate portion having a bifurcated shape in a plan view and a vertical wall portion continuous with the top plate portion.
With the metal plate pressed against the punch with a pad, the top plate portion, the intermediate vertical wall portion continuous with the top plate portion and the base end side of the vertical wall portion, and the bending continuous with the intermediate vertical wall portion. An overhang molding step in which the punch and the die cooperate to overhang the portion and the shelf portion continuous with the bent portion.
The trim process of removing unnecessary parts from the shelf part to form a flange part, and
A wrist-like step of bending back the bent portion to form the vertical wall portion including the intermediate vertical wall portion and the portion corresponding to the flange portion is provided.
The overhang molding step is a press molding method characterized in that the bending radius of the central portion of the branch portion in the bent portion is smaller than the bending radius of the portions on both sides in the bending ridge line direction of the central portion of the branch portion. .. A press-molding die for realizing the press-molding method according to claim 1.
The top plate portion, an intermediate vertical wall portion that is continuous with the top plate portion and is the base end side of the vertical wall portion, a bent portion that is continuous with the intermediate vertical wall portion, and a shelf portion that is continuous with the bent portion. The first mold for molding the intermediate molded product to have
A second mold for forming a flange portion by removing an unnecessary portion from the shelf portion, and
A third mold for forming the vertical wall portion including the intermediate vertical wall portion and the portion corresponding to the flange portion by bending back the bent portion is provided.
The first mold forms a punch having a top plate forming surface portion for forming the top plate portion, a pad arranged facing the punch and pressing a metal plate against the punch, and an intermediate vertical wall portion. It has an intermediate vertical wall portion molded surface portion, a die shoulder portion for forming the bent portion, and a die having a shelf portion molded surface portion for forming the shelf portion.
A press-molding die characterized in that the die shoulder R for forming the central portion of the branch portion in the die is set smaller than the die shoulder R for forming the portions on both sides in the bending ridge line direction of the branch central portion.

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