JP2024036855A - Method of press molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a press molding which can suppress a spring back when forming a bent projection strip part.

SOLUTION: One embodiment of this disclosure is a method of manufacturing a press molding for obtaining a press molding having a projection strip part provided with a concave bead and keeping the projection strip part bent so that the top plate may expand in a projecting direction from a lateral side view. The method of manufacturing a press molding includes a step of pre-molding an intermediate molding having a pre-projection part and a step of mainly molding a press molding by pressing the intermediate molding. The pre-molding step enables the formation of an expansion part expanding in the projecting direction of the pre-projection part in the top plate of the pre-projection part and keeping an apex arranged outside in the pre-projection strip part in a width direction from a concave bead scheduled region working as the concave bead of the press molding.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to a method for manufacturing a press-molded product.

2. Description of the Related Art A method of manufacturing a press-formed product having a convex stripe curved in the longitudinal direction by press working (that is, drawing) a metal plate is known (see Patent Document 1).

Japanese Patent Application Publication No. 2010-207906

In the above-described press-formed product, the length in the longitudinal direction of the inner curved region of the convex portion is smaller than the length in the longitudinal direction of the outer curved region, so tensile stress is generated on the inner side of the curve during press working. Therefore, when the press-formed product is taken out from the die, springback occurs in which the inside of the curve stretches due to residual stress. As a result, the dimensional accuracy of the product decreases.

One aspect of the present disclosure is to provide a method for manufacturing a press-formed product that can suppress springback when forming curved protrusions.

One aspect of the present disclosure is that the top plate has a convex portion provided with a concave bead along the longitudinal direction, and the top plate bulges in the direction in which the convex portion protrudes when viewed from the side of the convex portion. This is a method for manufacturing a press-formed product to obtain a press-formed product with curved protrusions as shown in FIG. The method for manufacturing a press-formed product includes the steps of: preforming an intermediate molded product having preliminary convex stripes by pressing a flat blank; and main-forming the press-formed product by pressing the intermediate molded product. Be prepared.

In the preforming process, the top plate of the preliminary convex strip bulges in the protruding direction of the preliminary convex strip, and the outer side of the preliminary convex strip in the width direction from the area where the concave bead is expected to become the concave bead of the press-formed product. forming at least one bulge having an apex located at the bulge;

According to such a configuration, the compressive stress in the concave bead is dispersed by crushing the bulge portion of the top plate of the preliminary convex portion having its apex outside the area where the concave bead is expected to be formed in the main molding. As a result, residual stress in the ridges is reduced, so springback of the press-formed product is suppressed.

In one aspect of the present disclosure, in the preforming step, a first bulge and a second bulge may be formed as at least one bulge. The apex of the first bulge and the apex of the second bulge may be arranged to sandwich the concave bead expected area in the width direction of the preliminary convex strip. According to such a configuration, compressive stress is dispersed on both sides of the concave bead during main molding, so that the effect of suppressing springback of the press-formed product is promoted.

In one aspect of the present disclosure, in the preforming step, the vertices bulge in the protruding direction of the preliminary convex strip only in a region of the preliminary convex strip that is outside the region in the width direction of the preliminary convex strip from the area where the concave bead is planned. may be formed. According to such a configuration, the concentration of compressive stress on the concave bead can be suppressed, thereby promoting the effect of suppressing springback of the press-formed product.

In one aspect of the present disclosure, in the preforming step, the concave bead expected region of the preliminary convex strip may be made to bulge out in the direction of protrusion of the preliminary convex strip beyond the concave bead of the press-formed product. According to such a configuration, it is possible to suppress an increase in the circumferential length of the preliminary ridged portion, so that the difference between the circumferential length of the preliminary ridged portion and the circumferential length of the ridged portion in the press-formed product is reduced. As a result, the dimensional accuracy of the press-formed product can be improved.

FIG. 1A is a schematic plan view of a press-formed product obtained by the method for manufacturing a press-formed product in the embodiment, FIG. 1B is a schematic side view of the press-formed product of FIG. 1A, and FIG. 1C is a schematic side view of the press-formed product of FIG. 1A. , is a schematic cross-sectional view taken along the line IC-IC in FIG. IA. FIG. 2 is a flowchart of a method for manufacturing a press-formed product in the embodiment. FIG. 3A is a schematic cross-sectional view of the preliminary ridge, and FIG. 3B is a schematic side view of the preliminary ridge. FIGS. 4A and 4B are schematic cross-sectional views of preliminary protrusions in an embodiment different from FIG. 3A. 5A and 5B are schematic cross-sectional views of a preliminary protrusion in an embodiment different from FIG. 3A.

Embodiments to which the present disclosure is applied will be described below with reference to the drawings.
[1. First embodiment]
[1-1. composition]
<Press molded product>
A press-formed product 1 shown in FIGS. 1A, 1B, and 1C is a metal molded product obtained by pressing a blank material. The press-formed product 1 has a convex portion 2, a first flange portion 3, a second flange portion 4, and a concave bead 5.

The protruding portion 2 is formed along the longitudinal direction of the press-formed product 1. The cross section of the protruding strip 2 perpendicular to the longitudinal direction is U-shaped. The protruding portion 2 includes a top plate 21, a first side plate 22, and a second side plate 23.

The top plate 21 is a band-shaped portion extending along the longitudinal direction of the press-formed product 1. As shown in FIG. 1B, the top plate 21 bulges in the protruding direction of the protruding strip 2 when viewed from the side of the protruding strip 2. In other words, the protruding part 2 is curved so that the top plate 21 bulges when viewed from the side of the protruding part 2, and the top plate 21 is curved with respect to the first flange part 3 and the second flange part 4. , located on the outside of the bend of the protruding portion 2.

The first side plate 22 and the second side plate 23 are connected to two ends of the top plate 21 in the width direction (that is, a direction orthogonal to the longitudinal direction), and are opposed to each other. The plate surfaces of the first side plate 22 and the second side plate 23 intersect with the plate surface of the top plate 21.

The first flange portion 3 and the second flange portion 4 are respectively disposed on the outside of the protruding strip portion 2 in the width direction and continuously with the protruding strip portion 2, and constitute ends of the press-formed product 1 in the width direction. There is. Specifically, the first flange portion 3 extends from the end of the first side plate 22 of the protruding strip 2 to the side opposite to the protruding strip 2 . The second flange portion 4 extends from the end of the second side plate 23 of the protruding portion 2 to the opposite side from the protruding portion 2 .

The concave bead 5 is a groove provided in the top plate 21 of the protruding strip 2 along the longitudinal direction of the protruding strip 2 . The concave bead 5 is concave in a direction opposite to the protruding direction of the convex strip 2 (that is, toward the first flange section 3 and the second flange section 4). The concave bead 5 is arranged at a position apart from each of the first side plate 22 and the second side plate 23 in the width direction of the protruding strip 2.

Although the use of the press-formed product 1 is not limited, the press-formed product 1 is suitably used as a member (for example, a front pillar, a center pillar, etc.) that constitutes the frame of an automobile. By using the press-formed product 1, springback can be suppressed without limiting the material used in the framework of an automobile that requires high strength and dimensional accuracy.

<Manufacturing method of press molded products>
As shown in FIG. 2, the method for manufacturing a press-formed product of this embodiment includes a preforming step S10 and a main molding step S20.

<Preforming process>
In this step, an intermediate molded product 101 shown in FIG. 3A is preformed by sandwiching and pressing a flat plate-shaped blank material between dies in the thickness direction. Note that the intermediate molded product 101 may be molded by pressing several times.

The intermediate molded product 101 has a preliminary convex portion 102, a first flange portion 3, and a second flange portion 4. The preliminary protruding portion 102 is a portion that is formed into the protruding portion 2 in the main forming step S20. The preliminary protruding portion 102 has a top plate 121, a first side wall 122, and a second side wall 123.

The top plate 121 has a concave bead expected region R that will become the concave bead 5 of the press-formed product 1 in the main molding step S20. Further, the top plate 121 is provided with a first bulge 124 and a second bulge 125.

The first bulging portion 124 and the second bulging portion 125 each bulge out in the direction in which the preliminary protruding portion 102 protrudes from the top plate 121 (that is, outward). The first bulging portion 124 and the second bulging portion 125 are arranged side by side in the width direction of the preliminary convex strip portion 102 .

Further, as shown in FIG. 3B, the first bulging portion 124 is divided into a plurality of portions in the longitudinal direction of the preliminary convex portion 102. As shown in FIG. The same applies to the second bulging portion 125. However, the first bulging portion 124 and the second bulging portion 125 may be continuously provided over the entire intended concave bead region R.

The apex P1 of the first bulging portion 124 is arranged in a portion closer to the first side wall 122 in a region outside the predetermined concave bead region R in the width direction of the preliminary convex strip portion 102. The apex P2 of the second bulging portion 125 is arranged in a portion closer to the second side wall 123 in a region outside the pre-convex strip portion 102 in the width direction than the concave bead expected region R.

In this embodiment, the apex P1 of the first bulging portion 124 is a point on the ridgeline of the first bulging portion 124 extending along the longitudinal direction of the preliminary convex strip 102. Further, the apex P2 of the second bulging portion 125 is a point on the ridgeline of the second bulging portion 125 extending along the longitudinal direction of the preliminary convex strip portion 102. The ridgeline of the first swollen portion 124 and the ridgeline of the second swollen portion 125 are each located outside the concave bead expected region R in the width direction of the preliminary convex strip portion 102 .

The apex P1 of the first bulge 124 and the apex P2 of the second bulge 125 are arranged to sandwich the concave bead expected region R in the width direction of the preliminary convex strip 102. In this embodiment, the heights (that is, the amount of bulge) of the apex P1 of the first bulge part 124 and the apex P2 of the second bulge part 125 from the top plate 21 in the press-molded product 1 are the same.

A portion of the first bulging portion 124 and a portion of the second bulging portion 125 are provided in the concave bead expected region R. Specifically, the connecting portion (that is, the valley) between the first bulging portion 124 and the second bulging portion 125 exists in the concave bead expected region R. Therefore, the concave bead expected region R bulges out further to the outside of the preliminary convex strip portion 102 than the concave bead 5 in the press-formed product 1 . On the other hand, in the concave bead expected region R, there is no apex of the bulge.

In this way, in this step, the first bulge 124 and the second bulge 125 are formed as part of the top plate 121 of the preliminary ridge 102. Further, in this step, no apex that bulges in the protruding direction of the preliminary convex strip 102 is formed in the concave bead expected region R. That is, in this step, a vertex that bulges in the protruding direction of the preliminary convex strip 102 is formed only in a region of the preliminary convex strip 102 that is outside the concave bead planned region R in the width direction of the preliminary convex strip 102. . Furthermore, in this step, the concave bead expected region R of the preliminary convex strip 102 is made to bulge out more than the concave bead 5 of the press-formed product 1 in the protruding direction of the preliminary convex strip 102 .

<Main molding process>
In this step, the intermediate molded product 101 is further sandwiched between dies and pressed, thereby forming the press molded product 1. Specifically, the preliminary protrusions 102 are pressed so as to crush the first protrusions 124 and the second protrusions 125, thereby forming the protrusions 2 and concave beads 5.

The top plate 121 of the preliminary convex portion 102 is a top plate having a concave bead 5 at the center in the width direction while dispersing compressive stress by crushing the first bulging portion 124 and the second bulging portion 125. 21.

[1-2. effect]
According to the embodiment detailed above, the following effects can be obtained.
(1a) The compressive stress in the concave bead 5 is dispersed by crushing the bulging portions 124 and 125 of the preliminary convex strip 102 whose apex is outside the concave bead expected region R on the top plate 121 in the main molding. As a result, the residual stress in the protruding portion 2 is reduced, so that the springback of the press-formed product 1 is suppressed.

(1b) By arranging the apex P1 of the first bulging part 124 and the apex P2 of the second bulging part 125 to sandwich the concave bead expected region R, compressive stress is applied to both sides of the concave bead 5 during main molding. is dispersed, so that the effect of suppressing springback of the press-formed product 1 is promoted.

(1c) By not forming a vertex that bulges in the protruding direction of the preliminary convex strip 102 in the concave bead planned region R, the concentration of compressive stress on the concave bead 5 can be suppressed, so that the springback of the press-formed product 1 can be suppressed. The inhibitory effect of

(1d) Since the increase in the circumferential length of the preliminary protruding portion 102 can be suppressed, the difference between the circumferential length of the preliminary protruding portion 102 and the circumferential length of the protruding portion 2 in the press-formed product 1 is reduced. As a result, the dimensional accuracy of the press-formed product 1 can be improved.

[2. Other embodiments]
Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above embodiments and can take various forms.

(2a) In the method for manufacturing a press-formed product of the above embodiment, two bulges do not necessarily need to be formed in the preforming step. For example, as shown in FIGS. 4A and 4B, only one bulge 124 may be formed in the preforming process. That is, only one vertex P1 may be provided outside the concave bead expected region R.

Note that in FIG. 4B, the apex P1 of the first bulging portion 124 is located at the center in the width direction of the top plate 121, but since the expected concave bead area R is shifted from the center in the width direction, the expected concave bead area Vertex P1 is not located in R.

(2b) In the method for manufacturing a press-formed product according to the above embodiment, a vertex that bulges in the direction of protrusion of the preliminary convex strip may be formed in the concave bead planned region in the preforming step. For example, as shown in FIG. 5A, a third bulge 126 may be formed in which the apex P3 is located in the concave bead expected region R in the preforming step.

(2c) In the method for manufacturing a press-formed product according to the above embodiment, in the preforming step, the region where the concave bead is to be formed does not necessarily need to bulge out in the direction of protrusion of the preliminary convex strips beyond the concave bead of the press-formed product. For example, as shown in FIG. 5B, the concave bead expected region R may be made to have the same shape as the concave bead 5 in the preforming process.

(2d) The function of one component in the above embodiment may be distributed as multiple components, or the functions of multiple components may be integrated into one component. Further, a part of the configuration of the above embodiment may be omitted. Further, at least a part of the configuration of the above embodiment may be added to, replaced with, etc. in the configuration of other embodiments. Note that all aspects included in the technical idea specified from the words described in the claims are embodiments of the present disclosure.

DESCRIPTION OF SYMBOLS 1... Press-formed product, 2... Convex strip part, 3... First flange part, 4... Second flange part,
5... Concave bead, 21... Top plate, 22... First side plate, 23... Second side plate, 101... Intermediate molded product,
102... Preliminary convex strip, 121... Top plate, 122... First side wall, 123... Second side wall,
124...first bulge, 125...second bulge, 126...third bulge,
P1, P2, P3...Vertex, R...Concave bead expected area.

Claims (4)

The top plate has a convex portion provided with a concave bead along the longitudinal direction, and the convex portion is configured such that the top plate bulges in the direction in which the convex portion protrudes when viewed from the side of the convex portion. A method for manufacturing a press-formed product for obtaining a press-formed product with curved stripes, the method comprising:
a step of preforming an intermediate molded product having preliminary convex stripes by pressing a flat blank material;
Mainly forming the press-formed product by pressing the intermediate molded product;
Equipped with
In the preforming step, the top plate of the preliminary convex strip bulges in the protrusion direction of the preliminary convex strip, and the preliminary convex portion is larger than the area where the concave bead is to become the concave bead of the press-formed product. A method for manufacturing a press-molded product, comprising forming at least one bulge portion having an apex disposed on the outside in the width direction of the strip portion. A method for manufacturing a press-formed product according to claim 1, comprising:
In the preforming step, a first bulge and a second bulge are formed as the at least one bulge,
The method for producing a press-molded product, wherein the apex of the first bulging portion and the apex of the second bulging portion are arranged to sandwich the concave bead expected area in the width direction of the preliminary convex strip. A method for manufacturing a press-formed product according to claim 1 or 2, comprising:
In the preforming step, a vertex that bulges in the protruding direction of the preliminary convex strip is formed only in a region of the preliminary convex strip that is outside the predetermined concave bead area in the width direction of the preliminary convex strip. A method for manufacturing press-formed products. A method for manufacturing a press-formed product according to claim 1 or 2, comprising:
In the preforming step, the concave bead expected region of the preliminary convex strip is expanded in a direction in which the preliminary convex strip is projected beyond the concave bead of the press-formed product.