[Name of Document] DESCRIPTION
[Title of the Invention] METHOD FOR MANUFACTURING PRESS-FORMED
PRODUCT AND PRESS-FORMING APPARATUS
[Technical Field]
5 [0001]
The present invention relates to a method for manufacturing a press-formed
product and a press-forming apparatus. More particularly, the present invention
relates to a method for manufacturing a press-formed product that is made of a hightensile
steel sheet having a tensile strength of 390 MPa or more and has a
10 substantially gutter-shaped cross section, and to a press-forming apparatus to be used
for manufacturing the press-formed product.
[Background Art]
[0002]
The floor of an automotive body (hereinafter simply referred to as "floor")
15 has rigidity to primarily resist the torsion and bending of the vehicle body when
driving the vehicle, and also transfers an impact load in a case of collision of the
vehicle. The floor also affects a weight of the automotive body significantly.
Accordingly, the floor is required to have mutually contradicting prope1iies, that is, a
high rigidity and a lightweight. The floor includes flat panels that are joined to each
20 other by welding, vehicle widthwise members that have substantially gutter-shaped
cross sections and are fixed to the flat panels along the vehicle widthwise direction,
and vehicle longitudinal members that have substantially gutter-shaped cross sections
and are fixed to the flat panels along the front-back direction of the vehicle body.
[0003]
25 The flat panels include, for example, a dash panel, a front floor panel, a rear
floor panel, and the like. The vehicle widthwise members are members fixed by
2
welding and disposed along the vehicle widthwise direction of these flat panels to
increase the rigidity and strength of the floor. The vehicle widthwise members
include, for example, floor cross members, seat cross members, and the like. The
vehicle longitudinal members are members fixed by welding and disposed along the
5 front-back direction of an automotive body to increase the rigidity and strength of the
floor. The outward flangevehicle longitudinal members include, for example, side
sills, side members, and the like. Among them, reinforcing members such as the
vehicle widthwise members and the vehicle longitudinal members are typically
joined to other members via outward flanges formed at ends of the reinforcing
10 members. For example, a floor cross member, which is an example of the vehicle
widthwise members, is joined to the tunnel portion of a front floor panel and to a side
sill via outward flanges that are formed at both ends of the floor cross member.
[0004]
FIGs. 19 (a) and 19 (b) illustrate a floor cross member 1, which is a
15 representative example of a member joined to other members with outward flanges 4
formed at both ends in the longitudinal direction of the member. FIG. 19 (a) is a
perspective view of the floor cross member 1 and FIG. 19 (b) is a view on the arrow
A in FIG. 19 (a).
20
[0005]
A front floor panel 2 is reinforced, for example, by a tunnel portion (not
shown) that is joined to the upper surface (indoor-side surface) of the front floor
panel 2, and also by a side sill 3 and the floor cross member 1. The tunnel portion
is a structural member projecting toward the inside of a vehicle along the
substantially widthwise center of the front floor panel 2. The side sill 3 is spot
25 welded to the upper surface of the front floor panel 2 at each widthwise edge of the
front floor panel 2. Both ends of the floor cross member 1 are spot welded to the
5
3
tunnel portion and the side sill 3 with the outward flanges 4 formed at both ends in
the longitudinal direction. This improves the rigidity of the floor and the load
transfer property when an impact load is applied.
[0006]
As described above, the floor cross member I is an impmtant structural
member to perform a fi.mction to improve the rigidity of an automotive body and to
absorb an impact load in a case of a lateral collision event. Accordingly, in an aim
to reduce body weight and improve collision safety, a high-tensile steel sheet of
smaller thickness and larger strength, such as, for example, a high-tensile steel sheet
10 having a tensile strength of 390 MPa or more (high-strength steel sheet or hightensile
strength steel sheet), has been used as a material for the floor cross member I
in recent years. However, there is still a strong demand for a floor cross member I
that has more i.Jnprov.ed load transfer prope1ty when an impact load is applied. To
address the demand, it is necessary to improve the load transfer property when an
15 impact load is applied, not only by increasing the material strength alone but also by
modifying the shape of the floor cross member 1.
[0007]
Although Patent Literatures 1 to 3 do not intend to form a floor cross
member, Patent Literatures 1 to 3 disclose inventions to solve defects in shape
20 fixation of press4bTined'J'Toducts made of high strength materials by modifying pad
mechanisms used with dies. These inventions have attempted to make an
improvement in the shape fixability after press forming by intentionally generating
deflection of a material during forming depending on the positional relationship
between the top of a punch and a flat pad of only a part that faces a flat part of the
25 top of the punch.
[Prior Art Literature]
[Patent Literatures]
[0008]
[Patent Literature I] JP 44 3 8468B
[Patent Literature 2] JP 2009-255116A
5 [Patent Literature 3] JP 2012-051005A
[Summary ofinvention]
4
[Problem(s) to Be Solved by the Invention]
[0009]
In order to increase the floor rigidity and the load transfer property of the
10 floor when an impact load is applied, it is preferable that the outward flanges formed
at both ends of the floor cross member are made continuous and joined to members
such as the tunnel portion of the floor front panel and the side sill. In other words,
it is preferable, .as will.be described later, that the outward flanges are formed also in
the ends in the longitudinal direction of ridges of the floor cross member, and are
15 made continuous along at least a gutter bottom and the ridges. Incidentally, the
term "outward flange" as used herein refers to a flange formed in the way that an end
of a formed product having a substantially gutter-shaped cross section is bent
outwardly from the gutter, and the term "outward continuous flange" refers to an
outward flange that is continuously formed along at least the ridges and the gutter
20 bottom.
[0010]
However, when forming the outward continuous flange including the ends
of the ridges by using press forming, such forming of the outward flange to be
formed in the ends of the ridges becomes stretched flange forming, which tends to
25 cause cracking in the edges of the outward flange. In addition, when forming the
outward continuous flange, which includes the ends of the ridges, by using press
5
forming, wrinkling tends to occur near the base of the flanges formed in the vicinity
of the ends of the ridges. These defects during press forming occur more often as
the material strength of the press-formed product becomes higher. Moreover, these
defects occur more often as a stretch flanging rate during flange forming in the ends
5 of the ridges becomes larger, in other words, as the angle e between the gutter bottom
lc and each vertical wall ld in FIG. 19 (b) becomes smaller. Furthermore, these
defects occur more often as the height h of the press-formed product in FIG. 19 (b)
becomes larger, because more tension in the outward flange is produced.
10
[0011]
There is a tendency that reinforcing members such as vehicle widthwise
members and vehicle longitudinal members are more strengthened as an automotive
body becomes lighter. In addition, such reinforcing members tend to be designed to
have a shape in which the stretch flanging rate becomes larger in forming the
outward continuous flange, due to prope1iy requirements and a shape of a joint for
15 joining to another member. In these circumstances, press forming methods known
in the art have had a difficulty in reducing cracking in the outward continuous flange
and wrinkling in the vicinity of the ends of the ridges. Accordingly, due to the press
forming constraints, notches have to be provided, by sacrificing propetiies of a
reinforcing member, at regions corresponding to ends of the ridges in the outward
20 flange formed in an end of the reinforcing member made of the high-tensile steel
sheet. In other words, the outward flange 4 has to be discontinuous due to notches
4a formed in the regions of the ends of the ridges 1a as illustrated in FIG. 19 (a) and
FIG.19(b).
25
[0012]
Furthermore, the phrase "provide a notch in a flange" as used herein is
meant to provide a notch formed in the whole width direction of the flange, which
6
makes the flange discontinuous. The term "the width of a flange" is used to have
the same meaning as the height of the flange. When the width of the flange is made
small partially but a part of the flange still remains, the notch is not meant to be
provided in the flange.
5 [0013]
With each of the known inventions disclosed in Patent Literatures 1 to 3, it
is difficult to form a desired outward continuous flange along at least a gutter bottom
and ridges in the end of the press-formed product that is made of a high-tensile steel
sheet having a tensile strength of 390 MPa or more and that has a gutter bottom,
10 ridges, and ve1tical walls that make a substantially gutter-shaped cross section.
Therefore, when the press-formed product having an outward flange is formed
according to the known inventions disclosed by Patent Literatures 1 to 3, it is
necessary to provide the notches in the regions in the ends of the ridges. That is to
say, when using the known inventions disclosed in Patent Literatures 1 to 3, the
' 15 press-formed products having the outward flange cannot be formed without lowering
the production yield of the press-formed products to be obtained.
[0014]
An object of the present invention is to provide a method for manufacturing
a press-formed product and a press-forming apparatus, which can reduce cracking in
20 the edge of the· outward continuous flange and wrinkling near the base of the flange
in the vicinity of the ends of the ridges in forming the press-formed product that is
made of a high-tensile steel sheet having a tensile stTength of 3 90 MPa or more and
that has a substantially gutter-shaped cross section and an outward continuous flange.
[Means for Solving the Problem(s)]
25 [0015]
In order to solve the above described problem, according to an aspect of the
7
present invention, there is provided a method of manufacturing a press-formed
product by press forming a forming material made of a high-tensile steel sheet of390
MPa or more, the press-formed product extending in a predetermined direction,
having a substantially gutter-shaped cross section intersecting the predetermined
5 direction, and including a gutter bottom, a ridge continuing to the gutter bottom, a
vertical wall continuing to the ridge, and an outward continuous flange being
continuously formed along at least the gutter bottom and the ridge in at least one end
in the predetermined direction, the method including: a first step in which, by using a
first press-forming apparatus including a first punch, a first die, a first pad, and a
10 second pad, the both pads facing the first punch, the first pad presses at least a part of
a portion to be formed into the gutter bottom in the forming material to press the
fmming material against the first punch in a marmer that an end of the forming
material continui11g to th
A method for manufacturing a press-formed product and a press-forming
apparatus according to an embodiment of the present invention are provided to
5 manufacture a press-formed product having an outward continuous flange of desired
shape. Accordingly, a press-formed product manufactured according to the present
embodiment will be first explained. The explanation will be made using an
exemplaty press-formed product in which the width of a gutter bottom or the height
of vettical walls gradually increases toward the end that has an outward continuous
10 flange (such a shape of a press-formed product is hereinafter referred to as a
"widening-toward-end shape").
[0028]
FIGs.) .((I) at}d 1 (b) illustrate an example of a press-formed product 10
manufactured using the method for manufacturing the press-formed product and the
15 press-forming apparatus according to the present embodiment. FIG. 1 (a) is a
perspective view illustrating a structural member 100 including a press-formed
product 10, and FIG. 1 (b) is a cross-sectional view taken along A-A in FIG. 1 (a).
[0029]
The press-formed product 10 is a press-formed product that is formed
20 extending in a predetermined direction (a direction designated by the arrow X in FIG.
1 (a), namely, an axial direction), and is made of a high-tensile steel sheet having a
tensile strength of 390 MPa or more measured by tensile testing in accordance with
JIS Z2241. The longitudinal direction of the press-formed product 10 illustrated in
FIG. 1 (a) serves as the predetermined direction. The predetermined direction,
25 however, is not limited to the longitudinal direction of the press-formed product 100.
[0030]
14
The press-formed product 10 illustrated in FIG. 1 (a) can be used as a
member constituting a structural member 100 of an automotive bodyshell.
Examples of the structural member 100 include a floor cross member, a side sill, a
front side member, and a floor tunnel brace. When the structural member l 00 is
5 used as a reinforcing member for an automotive body, such as the floor cross member,
the side sill, the front side member, the floor tunnel or the like, a high-strength steel
sheet having a tensile strength preferably of 590 MPa or more, and more preferably
of 780 MPa or more, is used as a forming material.
[0031]
10 Incidentally, as used herein, the term "structural member l 00" may
represent a press-formed product 10 (a first member) itself that excludes a second
member 18, or a composite member in which the press-formed product 10 (the first
member) is joined .to .the second member 18. For example, when the structural
member l 00 is used as a floor cross member, a floor panel corresponds to the second
15 member 18, and the press-formed product 10 itself, which is joined to the floor panel,
becomes the floor cross member serving as the structural member l 00. In
addition, when the structural member 100 is used as a side sill, the press-formed
product 10 (the first member) is joined to a closing plate or a second member having
a substantially gutter-shaped cross section, which is similar to the first member, to
20 form a cylim!riea!ly"shaped composite member, and the cylindrically-shaped
composite member serves as the structural member 100.
[0032]
Moreover, when the structural member l 00 is used as a front side member,
the cylindrically-shaped composite member made of the press-formed product 10
25 (the first member) and the second member, which is generally the same as the case of
the side sill, serves as the front side member. In the case of the front side member,
5
IS
however, the second member corresponds to, for example, a hood ridge panel, and
the press-formed product I 0 itself, which is joined to the hood ridge panel, is
sometimes referred to as the front side member.
[0033]
As illustrated in FIG. I (a), the press-formed product 10 has a gutter bottom
11, ridges 12a, 12b, vet1ical walls 13a, 13b, curved sections 14a, 14b, and flanges
!Sa, !Sb. The two ridges 12a, 12b are formed continuing to both widthwise ends of
the gutter bottom II. The two vertical walls 13a, 13 b are formed continuing to the
two ridges 12a, 12b, respectively. The two curved sections 14a, 14b are formed
10 continuing to the two vet1ical walls 13a, 13b, respectively. The two flanges !Sa,
!Sb are formed continuing to the two curved sections 14a, 14b, respectively.
[0034]
In addition, the two flanges !Sa, !Sb are joined to a second member 18 such
as, for example, a closing plate or a formed panel that constitutes a bodyshell (for
15 example, floor panel). In this way, the press-formed product 10 serving as the first
member and the second member 18 form a closed cross-sectional shape. It should
be noted that the curved section 14a, 14b continuing to the vet1ical walls 13a, 13b
and the flanges !Sa, !Sb continuing to the curved section 14a, 14b may be omitted
from the press-formed product manufactured using the method for manufacturing a
20 press-formed ·"Product and the press-forming apparatus according to the present
embodiment.
[003S]
The press-formed product 10 has an outward continuous flange 16 in a
longitudinal end. In the press-formed product I 0 illustrated in FIG. I (a) by way of
25 example, the outward continuous flange 16 is continuously formed, in the
longitudinal end, along the peripheral direction of the cross section of the gutter
16
bottom II, the ridges 12a, 12b, and the vetiical walls 13a, 13b. It is sufficient,
however, that the press-formed product I 0 according to the present embodiment has
the outward continuous flange 16 formed, in the longitudinal end, at least along the
gutter bottom 11 and the ridges l2a, 12b.
5 [0036]
The outward continuous flange 16 is formed in the longitudinal end of the
press-formed product 10 via a curved rising surface 17 having a curvature radius of r
(mm) (refer to FIG 1 (b)). In addition, the press-formed product 10 has a wideningtoward-
end shape in which the width of the gutter bottom 11 or the height of the
10 vetiical walls 13a, 13b gradually increases along the longitudinal direction toward
the end having the outward continuous flange 16. The press-formed product 10
preferably satisfies the relations expressed in the following formula (I):
L2xLI
5 The method for manufacturing a press-formed product and the pressforming
apparatus according to the present embodiment will now be described. As
described above, the method for manufacturing a press-formed product and the
press-forming apparatus according to the present embodiment are a method and an
apparatus to be used for manufacturing the press-formed product 10 having the
10 outward continuous flange 16 in at least one end in the predetermined direction as
illustrated in FIG. 1 (a) by way of example. The method for manufacturing the
press-formed product will now be outlined hereafter, and then a press-forming
apparatus 30 and the methoqfor manufacturing the press-formed product according
to the present embodiment will be described in detail.
15 [0047]
(2-1. Outline of Manufacturing Method)
The method for manufacturing a press-formed product according to the
present embodiment is first outlined. The method for manufacturing the pressformed
product according to the present embodiment includes a first step catl'ied out
20 by using a fust "f1l"=-forming apparatus and a second step carried out by using a
second press-forming apparatus.
[0048]
(2-1-1. Outline of First Step)
The first step is carried out by using the first press-forming apparatus. The
25 first press-forming apparatus corresponds to a press-forming apparatus according to
the present embodiment, which will be described later. In the first step, a first pad
21
presses at least a part of the portion to be formed into the gutter bottom in a forming
material. By doing so, the end of the forming material, which continues to the
portion to be formed into the gutter bottom, is raised in the direction opposite to the
pressing direction of the first pad. The first pad subsequently presses the forming
5 material against a first punch so that at least a part of the portion to be formed into
the gutter bottom is restrained by the first pad and the first punch.
[0049]
After the pmtion to be formed into the gutter bottom in the forming material
is restrained by the first pad, a second pad, which is different from the first pad,
10 presses at least a part of a longitudinal end of the portion to be formed into ridges in
the forming material. By doing so, the end of the forming material, which
continues to the pmtion to be formed into the ridges, is raised in the direction
opposite to the;: .pressil).g direction of the second pad. While the second pad
subsequently bends the portion to be formed into the ridges in the forming material
15 to the pressing direction of the second pad, the second pad and the first punch
restrain at least a part of the pmtion to be formed into the ridges.
[0050]
Subsequently, a first die is moved closer to the first punch to press fonn the
forming material while the forming material is restrained by the first and second pads
20 and the first}Jtmeh. 1'he·above-described first step forms an intermediate product
that has the outward continuous flange in a longitudinal end with cracking in the
flange and wrinkling in the vicinity of the ends of the ridges being reduced.
[0051]
(2-1-2. Outline of Second Step)
25 The second step is carried out by using the second press-forming apparatus,
which is different from the first press-forming apparatus. The first step uses the
22
first pad that restrains the portion to be formed into the gutter bottom and the second
pad that restrains the portion to be formed into the ridges. Accordingly, there
remains a part of the press forming material that is not completely pressed by the first
die and the first punch. Thus, the second step forms the press-formed product by
5 press forming the intermediate product using a second punch and a second die.
[0052]
The second press-forming apparatus may be a type of apparatus capable of
press forming the portion that the first press-forming apparatus does not form. In
pmiicular, the second press-forming apparatus may be a type of apparatus capable of
10 press forming the region that has not been restrained by the first pad or the second
pad in the portions to be formed into the gutter bottom, the ridges, and the vetiical
walls. Fmiher, the second press-forming apparatus may be a type of apparatus that
press forms th.e pmi of the outward continuous flange that the first press-forming
apparatus does not form. The second press-forming apparatus can be constituted by
15 a known press-forming apparatus having a die and punch.
[0053]
(2-2. Manufacturing Apparatus)
Now, the press-forming apparatus according to the present embodiment will
be described below. As described in the foregoing, the press-forming apparatus
20 according to the present embodiment is the first press-forming apparatus to be used
to form the intermediate product in the first step of the method for manufacturing a
press-formed product. FIG. 2 (a) and FIG. 2 (b) illustrate a schematic structure for
describing the exemplary first press-forming apparatus 30. FIG. 2 (a) is a sectional
view outlining a part of the first press-forming apparatus 30 that forms the end region
25 of the press-formed product, and FIG. 2 (b) is a perspective view outlining the first
press-forming apparatus 30. FIG. 2 (b) illustrates only half portions of a first punch
23
31 and a first pad 34-1, which are divided in half at the center line along the
longitndinal direction of the intermediate product to be formed.
[0054]
The first press-forming apparatus 30 has a first punch 31, a first die 32, and
5 a first pad 34-1 and a second pad 34-2 both of which face the first punch 31. The
first press-forming apparatus 30 is fundamentally configured to press form a forming
material by moving the first die 32 closer to the first punch 31 with the forming
material being restrained by the first and second pads 34-1, 34-2 and the first punch
31.
10 [0055]
The first punch 31 has punch surfaces on the sides facing the first die 32, the
first pad 34-1, and the second pad 34-2. The first punch 31 has an upper surface
3la, shoulders.Jlbj'or forming the ridges of the intermediate product, and a flangeforming
part 31 c.
15 [0056]
The first pad 34-1 has a restraining surface 34-1 a and a flange-forming part
34-lb. The restraining surface 34-1a of the first pad 34-1, which is disposed facing
the upper surface 31 a of the punch 31, presses the forming material against the upper
surface 31 a of the punch 31 and restrains the forming material. The part of the
20 forming material-that is restrained by the restraining surface 34-la and the upper
surface 31a is the pmiion to be formed into the gutter bottom. The restrained part
of the forming material may be the whole pmiion or a part of the portion to be
formed into the gutter bottom. However, at least the vicinity of the end on the side
having the outward continuous flange in the portion to be formed into the gutter
25 bottom is made to be restrained. The flange-forming pmi 34-lb of the first pad 34-
1 presses the forming material against the flange-forming part 31c of the punch 31.
24
By doing so, the flange to be formed in the end of the gutter bottom in the forming
material is bent upward.
[0057]
The second pad 34-2 has restraining surfaces 34-2a and a flange-forming
5 part 34-2b. The second pad 34-2 is disposed in the way that it does not interfere
with the first pad 34-1 .in press forming. Each restraining surface 34-2a of the
second pad 34-2, which is disposed facing the shoulder 3lb of the punch 31, presses
and then restrains the forming material against the shoulder 31 b of the punch 31.
The part of the forming material restrained by the restraining surface 34-2a and the
10 shoulder 31 b is at least a pmi of the end region of the potiion to be formed into each
ridge. The flange-forming part 34-2b of the second pad 34-2 presses the forming
material against the flange-forming part 31 c of the punch 31. In this way, the flange
to be formed in the end.of each ridge in the forming material is bent upward.
15
[0058]
The second pad 34-2 restrains the pmtions to be formed into ridges in the
vicinity of the outward continuous flange while the portion to be formed into the
gutter bottom is restrained by the first pad 34-1. Accordingly, the shapes of the
ridges in the vicinity of the outward continuous flange is formed by projecting
outward the material approximately in the region pressed by the second pad 34-2.
20 This restrains 1he movement ·of the material surrounding the region contacted by the
second pad 34-2, and thus reduces stretch or shrinkage deformation of the
surrounding material, which otherwise causes cracking and wrinkling.
Consequently, the generation of cracking of stretched flange in the region
corresponding to the ridge in the outward continuous flange, and the generation of
25 wrinkling near the base of the flange at the ridges in the vicinity of the ends of the
ridges can be reduced.
25
[0059]
In addition, the second pad 34-2 is aimed at projecting outward the material
in the vicinity of the outward continuous flange and forming the ridges so as to
reduce the movement of the surrounding material. For tllis purpose, it is preferable
5 that the second pad 34-2 restrains the whole pmiions to be formed into the ridges in
the vicinity of the potiion to be formed into the outward continuous flange, starting
from the border between the portion to be formed into the gntter bottom and the
portions to be formed into the ridges.
10
[0060]
More specifically, it is preferable that the region of the forming material that
is restrained by the restraining surface 34-2a of the second pad 34-2 includes the
border between the portion to be formed into the gntter bottom and the pmiion to be
formed into each ridge. It ,is,pmiicularly preferable that the second pad 34-2
restrains the region of at least 1/3 of the perimeter length of the cross section starting
15 from the above-described border in the pmiions to be formed into the ridges 12a, 12b.
The second pad 34-2 presses the above-mentioned region, while restraining the
movement of the surrounding steel sheet material and projecting outward the steel
sheet material in the region pressed by the restraining surface 34-2a of the second
pad 34-2, so that a part of each ridge 12a, 12b can be formed. It should be noted
20 that the second·~ 34-2 may'be· configured to press the ridge and a pmi of the
vertical wall, in other word, a region of 20 nm1 or less in length of the vetiical wall
that continues to the ridge, for example.
[0061]
Other properties of the first pad 34-1 and the second pad 34-2, such as
25 dimensions and materials, can be the same as those of pads known in the art.
[0062]
26
The first die 32 is moved closer to the first punch 31 to press form the
forming material with the forming material being restrained by the first pad 34-l and
the second pad 34-2. The first die 32 is disposed in the way that it does not
interfere with the first pad 34-1 and the second pad 34-2 during press forming. The
5 first pad 34-1, the second pad 34-2, and the first die 32 are preferably arranged with a
minimum spacing with respect to the pressing direction.
[0063]
The first press-forming apparatus 30 according to the present embodiment is
configured to have the first pad 34-1, the second pad 34-2, and the first die 32 press
10 the forming material in this order. In other words, the second pad 34-2 restrains the
end region in the p01tions to be formed into the ridges after at least a part of the
portion to be formed into the gutter bottom is restrained by the first pad 34-1. The
first die 32 subs~quent\yp(ess forms the forming material with the forming material
being restrained by the first pad 34-1 and the second pad 34-2.
15 [0064]
This configuration has been achieved in the present embodiment by
suspending the first pad 34-1 and the second pad 34-2 from the die 32 with coil
spnngs. More specifically, the restraining surface 34-la of the first pad 34-1, the
restraining surfaces 34-2a of the second pad 34-2, and the press surface of the first
20 die 32 are arranged·inthis·order from the side of the first punch 31 in the state before
press forming. By moving the first die 32 toward the first punch 31, the first die 32
press forms the forming material after the first pad 34-1 and the second pad 34-2
consecutively contact with, and then restrain, the forming material in this order.
Subsequently, the first die 32 press forms the forming material.
25 [0065]
It should be noted that one or all of the first pad 34-1, the second pad 34-2,
27
and the first die 32 may be configured to be able to move independently toward the
first punch 31. In this case, the order of contacting with the forming material is
controlled by controlling each movement of the first pad 34-1, the second pad 34-2,
and the first die 32.
5 [0066]
Jncidentally, due to the presence of the first pad 34-1 or the second pad 34-2,
there are regions in which the first die 32 does not press the forming material against
the first punch 31. For example, the first die 32 does not press form vertical walls
and the flanges that are overlapped by the second pad 34-2 in the pressing direction.
10 These regions are press formed by the second press-forming apparatus in the second
step. The second press-forming apparatus can be configured using a press-forming
apparatus known in the ati, and fmiher description thereon is omitted.
[0067]
(2-3. Manufacturing Method)
15 Now, the method for manufacturing a press-formed product according to the
present embodiment will be described specifically. The method for manufacturing
a press-formed product according to the present embodiment is an exemplary method
illustrated by way of example in FIG. I (a) for manufacturing the press-formed
product 10 having the widening-toward-end shape and the outward continuous flange
20 16.
[0068]
(2-3-1. First Step)
FIGs. 3 to 7 are schematic views conceptually illustrating the first step
carried out by using the first press-forming apparatus 30 as described above. FIGs.
25 3 (a) and 3 (b) are a cross-sectional view and a perspective view, schematically
illustrating a state in which a forming material 33 is restrained by the first pad 34-1.
28
FIGs. 4 (a) and 4 (b) are a cross-sectional view and a perspective view, schematically
illustrating a state in which the forming material 33 is restrained by the second pad
34-2. FIG. 7 is a cross-sectional view schematically illustrating a state in which the
forming material 33 is press formed by the first die 32.
5 [0069]
It should be noted that FIGs. 3 to 7 illustrate the first step in manufacturing
the press-formed product 10 having a widening-toward-end shape. In addition, FIG.
3 (a), FIG. 4 (a), and FIG. 7 (a) illustrate a state in which the first step forms an end
region in the longitudinal direction in the forming material 33, in which the outward
10 continuous flange 16 is formed. FIGs. 3 (b) and 4 (b) illustrate only a half portion
of the first punch 31, the first pad 34-1, and the forming material 33, which are
divided in half at the center line along the longitudinal direction of an intermediate
product to be formed. Moreover, a manufacturing method as described below uses
the first press-forming apparatus 30 in which the first pad 34- I and the second pad
15 34-2 are suspended from the first die 32.
[0070]
In the first step as illustrated in FIGs. 3 (a) and 3 (b), as the first die 32
moves toward the first punch 31, the first pad 34-1 restrains the portion to be formed
into the gutter bottom 11 in the forming material 33. At this time, as illustrated in
20 FIG. 3 (b), the restraining surface 34-la of the first pad 34-1 restrains at least a part
of the portion to be formed into the gutter bottom II in the forming material 33. At
the same time, a longitudinal end of the forming material 33 is raised in the direction
opposite to the pressing direction, and then restrained by the flange-forming part 34-
lb of the first pad 34-1 and the flange-forming part 3Jc of the first punch 31.
25 [0071]
Subsequently, as the first die 32 moves further toward the first punch 31, the
29
second pad 34-2 restrains the portion to be formed into each ridge 12a, 12b in the
forming material 33, as illustrated in FIGs. 4 (a) and 4 (b). At this time, the
restrained region in the forming material 33 is a region in the vicinity of the end of
the portion to be formed into each ridge 12a, 12b. In other words, the restraining
5 surfaces 34-2a of the second pad 34-2 restrain the end of the pmiions to be formed
into the ridges 12a, 12b in the forming material 33, as illustrated in FIG. 4 (b). At
the same time, the pmiion to be formed into the flange, which continues to the
portion to be formed into each ridge 12a, 12b, is finiher raised in the direction
opposite to the pressing direction, and then restrained by the flange-forming part 34-
10 2b of the second pad 34-2 and the flange-forming part 31 c of the first punch 31.
[0072]
It is preferable at this time that the second pad 34-2 presses the region of at
least 1/3 ofthepe.rimete!)epgth of the cross section starting from the aforementioned
border in the portion to be formed into each ridge 12a, 12b. The second pad 34-2
15 presses this region, while restraining the movement of the sunounding steel sheet
material and projecting outward the steel sheet material in the region pressed by the
restraining surface 34-2a of the second pad 34-2, so that a part of each ridge 12a, 12b
can be formed.
[0073]
20 FIG. ·5· is a ·characteristic diagram illustrating a relationship between an
extent pressed by the second pad 34-2 in the portion to be formed into the ridge and a
minimum decrease rate of sheet thickness in the edge of the flange pmiion that
continues to the ridge 12a or 12b in the outward continuous flange 16 to be formed.
In FIG. 5, the pressed extent is represented by a pressing angle that means a central
25 angle of the extent that the second pad 34-2 restrains, where the border between the
portion to be formed into each ridge and the portion to be formed into the gutter
30
bottom is set to 0°. The pressing angle of 0° means a state in which the portion to
be formed into the ridge is not restrained.
[0074]
As shown in FIG. 5, when the pmtion to be formed into the ridge is not
5 restrained, a minimum decrease rate of sheet thickness in the edge of the flange is
approximately 36%, which indicates a high possibility of generating cracking of
stretched flange. In contrast, when restraining with a pressing angle of 23 ° or more,
in other words, restraining the ridge region of at least 1/3 of the perimeter length of
the cross section starting from the border, a minimum decrease rate of sheet thickness
10 in the edge of the flange is suppressed to less than 25%. Accordingly, this shows
that cracking in the edge of the flange is reduced.
[0075]
FIG. 6 is al~o,a characteristic diagram illustrating a relationship between an
extent pressed by the second pad 34-2 in the portion to be formed into the ridge and a
15 minimum decrease rate of sheet thickness near the base of the flange in the vicinity
of the end of the ridge 12a or 12b to be formed. In FIG. 6, the pressed extent is also
represented by the pressing angle as is in FIG. 5. As shown in FIG. 6, when the
portion to be formed into the ridge is not restrained, a minimum decrease rate of
sheet thickness near the base of the flange is approximately -65%, which apparently
20 leads to wrinkling generation. In contrast, when restraining with a pressing angle of
23° or more, in other words, restraining the ridge region of at least 1/3 of the
perimeter length of the cross section stmting from the border, a minimum decrease
rate of sheet thickness near the base of the flange is suppressed to -35% or less.
Accordingly, this shows that wrinkling near the base of the flange is reduced.
25 [0076]
Subsequently, as the first die 32 moves fi.ather toward the first punch 31, the
31
first punch 31 and the first die 32 carry out a first stage press forming with the
forming material 33 being restrained by the first pad 34-1 and the second pad 34-2,
as illustrated in FIG. 7. By doing so, the forming material 33 is press formed into
the intermediate product except, for example, the portion located below the second
5 pad 34-2 in the pressing direction (33A in FIG. 7).
[0077]
The first stage press forming using the first punch 31 and the first die 32
may be bending forming in which the first die 32 presses and bends the forming
material 33 against the first punch 31. Alternatively, the first stage press forming
10 may be deep drawing in which the first die 32 and a blank holder move toward the
first punch 31 to carry out press forming while the first die 32 and the blank holder
clamp the portions to be formed into the vet1ical walls in the forming material33.
[0078]
At this time, the second pad 34-2 is restraining the region in the vicinity of
15 the end of the portion to be formed into each ridges 12a, 12b (near the border
between the ridge 12a or 12b and the outward continuous flange 16) so that
wrinkling generation is reduced in the region. In addition, because of the second
pad 34-2 restraining this region, the stretch flanging rate of the flange that is
continuously formed in the end of each ridge 12a, 12b is reduced, which enables
20 reduction in craclcing -generation· in the outward continuous flange 16. Incidentally,
although not shown in FIGs. 3 to 7, a pmt of the curved sections 14a, 14b and the
flanges !Sa, 15b in the press-formed product 10 illustrated by way of example in FIG.
1 are press formed by the first punch 31 and the first die 32 in the first step.
[0079]
25 Now, there will be described below a reason why wrinkling near the base of
the flange in the end region of the ridge 12a or 12b and cracking in the edge of the
32
outward continuous flange 16 are reduced by using the method for manufacturing a
press-formed product according to the present embodiment. FIG. 8 is a view for
explaining the press forming that uses a pad 134 in which the first pad and the
second pad are not separated so that the pmtion to be formed into the gutter bottom
5 and the pmtions to be formed into the ridges are restrained simultaneously. The
press-formed product to be formed is shaped as a press-formed product having a
widening-toward-end shape as illustrated in FIG. 1 (a). FIG 8 (a), which
corresponds to FIG. 4 (b), is a perspective view illustrating a state in which a punch
131 and the pad 134 are restraining the pmtion to be formed into the gutter bottom
10 and the pmtions to be formed into the ridges in a forming material133. In addition,
FIG. 8 (b) is a view in which the forming material 133 is being pressed by the die,
which is viewed from above.
[0080]
In the case of using the pad 134, when the pad 134 presses and restrains the
15 forming material 133 against the punch 131, the portions to be formed into the ridges
are first pressed by the pad 134. In this state, a gap is created between the portion
to be formed into the gutter bottom and the pad 134, and the portion to be formed
into the gutter bottom is not pressed by the pad. In addition, the press-formed
product having the widening-toward-end shape has different perimeter lengths of
20 cross sections depending on the locations in the longitudinal direction in the vicinity
of the end of the portion to be formed into the gutter bottom. In other words, the
perimeter length of the cross section at the location Z1 is longer than that at the
location Z2 as illustrated in FIG. 8 (a).
25
[0081]
As a result, the steel sheet material for the pmtion to be formed into the
outward flange is moved from the portion to be formed into the gutter bottom toward
5
33
the portions to be formed into the ridges, until the pad 134 restrains both portions to
be formed into the gutter bottom and to be formed into the ridges together, as
illustrated in FIG. 8 (a).
[0082]
Moreover, in the case of the press-formed product having a wideningtoward-
end shape, the portions to be formed into vertical walls, which are bent by the
die, is bent in the vertical direction relative to a portion 112 to be formed into the
ridges, in other words, bent in a direction of moving away from a pmtion 116 to be
formed into the outward flange, as illustrated in FIG. 8 (b). This makes the steel
10 sheet material for the pmtion to be formed into the outward flange easier to move
toward the portion to be formed into the ridges. Consequently, this tends to cause
excessive wrinkling and thickening in the portion to be formed into the ridges. For
the reasons, in the case of using the pad 134 that simultaneously restrains the pmtion
to be formed into the gutter bottom and the portions to be formed into the ridges, the
15 wrinkling tends to occur in the end of the portion to be formed into the gutter bottom
and in the end of the portions to be formed into the ridges.
[0083]
In contrast, according to the present embodiment, the second pad 34-2
presses and restrains the ends of the portions to be formed into the ridges after the
20 first pad 34-i restrains the portion to be formed into the gutter bottom as illustrated
in FIGs. 3 (b) and 4 (b). Accordingly, while the ends of the pmtions to be formed
into the ridges are pressed by the second pad 34-2, the movement of the steel sheet
material toward the portion to be formed into the gutter bottom is reduced. As a
result, even though there exist different perimeter lengths of the cross section
25 depending on a longitudinal location in the end of the pmtion to be formed into the
gutter bottom (in the vicinity of the outward continuous flange), the movement of the
34
steel sheet material for the pmtion to be formed into the outward continuous flange
toward the pmtion to be formed into the gutter bottom and the portions to be formed
into the ridges is reduced.
[0084]
5 Moreover, while the pmtion to be formed into the gutter bottom is restrained
by the first pad 34-1, the second pad 34-2 presses the end of the pmtion to be formed
into each ridge, so that the end of the portion to be formed into each ridge is formed
in the way that the steel sheet material in the pressed region is projected outward.
Fmihermore, according to the present embodiment, the first punch 31 and the first
10 die 32 press form the forming material 33, while the forming material 33 is restrained
by the first pad 34-1 and the second pad 34-2, as illustrated in FIG. 7. Consequently,
an excessive steel sheet material movement toward the pmtion to be formed into the
ridges is reduced. As a result, an excessive thickening and wrinkling in the end of
each ridge 12a, 12b to be formed are reduced.
15 [008S]
(2-3-2. Second Step)
As described above, after the first stage press forming has been carried out
in the first step, a second stage press forming is carried out in the second step. In
the first step, the pmtions to be formed into the vettical walls 13a, 13b, which are
20 overlapped by 'the second pad 34-2, among portions below the second pad 34-2 along
the pressing direction, are not formed into final shapes as the press-formed product
10. The whole portions or a pat1 of the portions to be formed into the curved
sections 14a, 14b and the flanges !Sa, !Sa in the press-formed product 10 may not be
formed into final shapes in the first step, either.
25 [0086]
Furthermore, a pat1 of the pmiions to be formed into the ridges 12a, 12b
35
may not be formed into final shapes in the first step either, depending on the region
that the first pad 34-1 and the second pad 34-2 press in the forming material 33.
For example, when the second pad 34-2 forms a region of 1/3 of the perimeter length
of the cross section in the pmiion to be formed into the ridge 12a or 12b starting from
5 the border between the portion to be formed into the ridge 12a or 12b and the portion
to be formed into the gutter bottom 11 in the first step, the remaining region of 2/3 of
the perimeter length of the cross section needs to be pressed later.
[0087]
Accordingly, the second punch and the second die in the second step using
10 the second press-forming apparatus carry out the second stage press forming to press
the intermediate product and form the press-formed product 10 having the final
shape. The second step can be carried out by the known press forming method
using the second punch and the second die that have press surfaces corresponding to
portions to be formed into the final shapes. If the second step does not complete
15 forming into the final shape of the press-formed product 10, another forming step
may be futiher added.
[0088]
Incidentally, the second step may be stamping press forming using only a
die and punch without using pads, or may be typical press forming using pads.
20 [0089]
<3. Conclusion>
As described above, in accordance with the method for manufacturing a
press-formed product, which includes the press-forming apparatus (the first pressforming
apparatus) 30 and the first step using the first press-forming apparatus 30
25 according to the present embodiment, there is obtained the press-formed product
having the outward continuous flange formed from the gutter bottom to vertical walls
36
in the end in the predetermined direction. In the first step, the first pad restrains at
least a part of the portion to be formed into the gutter bottom, and then the second
pad restrains at least a part of the end of the portion to be formed into each ridge.
Further in the first step, the die and punch press form the forming material with the
5 forming material being restrained by the first and second pads.
[0090]
In this way, the movement of the steel sheet material, from the pmiion to be
formed into each ridge toward the portion to be formed into the gutter bottom, is
reduced while the portion to be formed into each ridge is pressed by the second pad.
10 In addition, the second pad forms the shape of the ridge in the end of the portion to
be formed into each ridge by projecting the material in the pressed region outward.
Accordingly, even though the press-formed product made of a high-tensile steel sheet
having a tensile strepgth of390· MPa or more is formed, the movement of the
material surrounding the region that is contacted by the second pad is reduced, and
15 thus the stretch or shrinkage deformation of the surrounding material are also
reduced, which otherwise causes cracking and wrinkling.
[0091]
As a result, the generation of cracking of stretched flange in the flange
portion corresponding to each ridge in the outward continuous flange and wrinkling
20 near the base ·of·1he 'flange·in the vicinity of the end of the ridge can be reduced.
The method for manufacturing a press-formed product and the press-forming
apparatus are especially effective in manufacturing a press-formed product having a
widening-toward-end shape in which the width of the gutter bottom or the height of
the vertical walls gradually increases toward the end having the outward continuous
25 flange. Structural members for an automotive body constituted by the press-formed
product formed in this way can improve the rigidity and the property of transferring
37
an impact load.
[0092]
A preferred embodiment has been described so far with reference to the
accompanied drawings. The present invention, however, is not limited to above-
5 described example. It will be evident that those skilled in the mt to which the
present invention pertains may conceive various alternatives and modifications while
remaining within the scope of the technical idea as described in the claims. It should
be understood that such alternatives and modifications apparently fall within the
technical scope of the present invention.
10 [0093]
For example, in the above-described embodiment, the method for
manufacturing a press-formed product and the press-forming apparatus have been
described using the eXCl.J.lp,l;py press-formed product 10 having a widening-towardend
shape and an outward continuous flange. However, the press-formed product to
15 be manufactured according to the present invention is not limited to that example.
The present invention can also be applied to a press-formed product that has a
constant-width gutter bottom and constant-height vertical walls and does not have a
widening-toward-end shape.
[Example( s)]
20 [0094]
Examples of the present embodiment will now be described.
[0095]
(1) Example 1 and Comparative Examples 1, 2
First, a decrease rate of sheet thickness in the end of the ridge in a press-
25 formed product 10 manufactured according to the method for manufacturing a pressformed
product of the present embodiment was evaluated. In Example 1, a press38
formed product was manufactured using the first pad 34-1 and the second pad 34-2
according to the method for manufacturing a press-formed product of the present
embodiment. In Comparative Example 1, a press-formed product was also
manufactured with the same conditions as in Example I, except for using a pad that
5 restrained only a gutter bottom instead of using the first pad and the second pad.
Further, in Comparative Example 2, a press-formed product was manufactured with
the same conditions as in Example I, except for using a pad that restrained the gutter
bottom and the ridges simultaneously instead of using the first pad and the second
pad.
10 [0096]
The forming material 3 3 used was a 1.4 mm thick steel sheet having a
tensile strength of 980 MPa class measured by tensile testing in accordance with JIS
Z 2241. In additio!j., a,.press-formed product had a substantially gutter-shaped cross
section of 100 nnn in height, 76 mm in gutter bottom width L1, and 148 mm in gutter
15 bottom width L2, and an outward continuous flange of 14 mm in flange width. The
shoulders of a punch used had a curvature radius of 12 mm.
[0097]
FIG. 9 is a schematic view showing analytical results on the decrease rate of
sheet thickness for the press-formed products of Example 1 and Comparative
20 Examples 1, 2. FIG; 9 (a) is a view showing an analysis region A where the
decrease rate of sheet thickness was analyzed. In FIG. 9 (a), a half of the pressformed
product 10, which is divided in half at the center line along the axial direction
(x direction), is shown. FIG. 9 (b) shows an analytical result on the press-formed
product according to Comparative Example 1, and FIG 9 (c) shows an analytical
25 result on the press-formed product according to Comparative Example 2. FIG 9 (d)
shows an analytical result on the press-formed product I 0 according to Example 1.
39
For the analyses, LS-DYNA, a general-purpose analysis software application, was
used.
[0098]
The press-formed product according to Comparative Example I, which used
5 the pad restraining only the gutter bottom, exhibited a decrease rate of sheet
thickness of 24.8% at a location I in the flange formed continuing to the end of a
ridge in the outward continuous flange, as shown in FIG. 9 (b). This decrease rate
of sheet thickness raises the concern of generating forming defects (cracking). The
press-formed product according to Comparative Example 2, which used the pad
10 restraining the gutter bottom and the ridges simultaneously, exhibited a low decrease
rate of sheet thickness of 11.2% at a location HI in the flange fotmed continuing to
the end of a ridge in the outward continuous flange, as shown in FIG. 9 (c). On the
other hand, the press-formed product according to Comparative Example 2 exhibited
a decrease rate of sheet thickness of -15.5% at a location H2 in the curved rising
15 surface between the end of the ridge and the outward continuous flange, as shown in
FIG. 9 (c), which raises the concern of generating wrinkling and thickening beyond
tolerance.
[0099]
In contrast, the press-formed product according to Example I, which used
20 the first pad and the second pad, exhibited a decrease rate of sheet thickness of
15.4% at a location Jl in the flange fotmed continuing to the end of a ridge in the
outward continuous flange 16 as shown in FIG 9 (d), which was within tolerance.
Moreover, a decrease rate of sheet thickness was -13.9% at a location J2 in the
curved rising surface between the end of the ridge and the outward continuous flange
25 16 as shown in FIG 9 (d), with which the generation of wrinkling and thickening
were within tolerance.
40
[0100]
(2) Example 2 and Comparative Examples 3, 4
An axial load generated in an impact event and an impact energy absorption
amount were evaluated by exerting an impact load, in the axial direction, on the end
5 having an outward continuous flange 16 in the press-formed product I 0
manufactured according to the method for manufacturing a press-formed product of
the present embodiment. Prope1iies of the press-formed product having the
widening-toward-end shape and the outward continuous flange, which was
preferably manufactured by using the method for manufacturing a press-formed
10 product and the press-forming apparatus according to the present embodiment, were
evaluated.
[0101]
FIG. 10 is. a .sch~matic view illustrating analytical models of stmctural
member used in the analyses. FIG. 10 (a) illustrates an analytical model 50
15 according to Comparative Example 3, and FIG. 10 (b) illustrates an analytical model
60 according to Comparative Example 4. FIG. 10 (c) illustrates an analytical model
70 according to Example 2. In each analytical model 50, 60, 70, a press-formed
product 10, 51, or 61, which is a first member having a substantially gutter-shaped
cross section, is joined to a flat-plate second member 18 via flanges 26 that continue
20 to vertical walls4i·ilrrough curved sections 27.
[01 02]
The analytical model 50 according to Comparative Example 3 has, in an
axial end, an outward continuous flange 23 without having notches. In addition, the
analytical model 50 has a shape in which the width of the gutter bottom and the
25 height of the vertical walls are constant (the width of the gutter bottom = I 00 mm).
The press-formed product 51 of the analytical model 50 is formed by press forming
41
with the pad (pad 134 in FIG. 8 (a)) that simultaneously restrains the pmiion to be
formed into the gutter bottom and the pmiions to be formed into the ridges.
[0103]
The analytical model 60 according to Comparative Example 4 has, in an
5 axial end, a discontinuous outward flange 24 having notches that reach the end of the
ridge 25b. In addition, the analytical model 60 has a shape in which the width of
the gutter bottom gradually increases toward the end having the outward flange 24.
A minimum width of the gutter bottom is 100 mm and a maximum width is 130 mm.
The press-formed product 61 of the analytical model 60 is formed by press forming
10 with the pad that restrains only the portion to be formed into the gutter bottom.
[01 04]
The analytical model 70 according to Example 2 has, in an axial end, an
outward contitruol.IS fla11ge 16 without having notches. In addition, the analytical
model 70 has a shape in which the width of the gutter bottom gradually increases
15 toward the end having the outward flange 24, which is the same as in Comparative
Example 4 (the width of the gutter bottom is increased from 100 mm to 130 mm).
The press-fmmed product 10 of the analytical model 70 is formed by press forming
with the first pad 34-1 and the second pad 34-2 as illustrated in FIGs. 3 to 7.
[0105]
20 Analysis ·conditions other than the foregoing were all set the same for the
analytical models 50, 60, 70. The common analytical conditions are listed as
follows:
- Steel sheet used: a 1.4 mm thick high-tensile steel sheet having a tensile strength of
980 MPa class
25 - Height of substantially gutter-shaped cross section: I 00 mm
- Curvature radius of ridge: 12 mm
42
- Curvature radius of curved section 27 continuing to flange 26: 5 nm1
-Widths of outward continuous flange 16 and outward flange 24: 14 nun
-Curvature radius r of curved rising surface 28: 3 mm
- Length in the axial direction: 300 mm
5 [0106]
In performing analysis, as illustrated in FIG. 10 (a), a rigid wall 29 was
made to collide, in the axial direction at a collision speed of20 km/h, against the end
formed with the outward continuous flange 16, 23 or the outward flanges 24 to cause
axial displacement in each analytical model 50, 60, 70. The axial load (k:N)
10 generated in the collision and the impact energy absorption amount (k:J) were then
calculated for each of Example 2 and Comparative Examples 3, 4.
[0107]
FIG. 1 I is 11!\fn prqp,t;J;zy has been shown relatively better.
15
[0123]
As described in the foregoing, the analytical model 70, which includes the
press-formed product 10 having the outward continuous flange 16 and the wideningtoward-
end shape, is made to increase the axial load in the initial stage and the late
stage of axial crushing. In addition, the analytical model 70 generates buckling
with small buckling pitch therebetween near the end to which an impact load is
20 applied. Accordingly, ·the analytical model 70 is shown to have excellent load
transfer property and excellent impact energy absorption prope1ty. The method for
manufacturing a press-formed product and the press-forming apparatus according to
the present invention can reduce cracking generation in the edge of the outward
continuous flange 16 and wrinkling generation near the base of the flange in the ends
25 of the ridges 12a, 12b, in manufacturing the press-formed product 1 0 that constitutes
the aforementioned analytical model 70.
5
10
15
[Reference Signs List]
[0124]
10 press-formed product
11 gutter bottom
12a, 12b ridge
13a, 13b vertical wall
14a, 14b curved section
15a, 15b flange
16 outward continuous flange
18 second member
49
30 press-forming apparatus (the first press-forming apparatus)
31 punch (first punch)
32 die (frrsUii").
33 forming material
34-1 first pad
34-2 second pad
100 sttuctura1 member

[Name of Document] CLAIMS
[Claim I]
A method of manufacturing a press-formed product by press forming a
forming material made of a high-tensile steel sheet of 390 MPa or more, the press-
5 formed product extending in a predetermined direction, having a substantially guttershaped
cross section intersecting the predetermined direction, and including
a gutter bottom,
a ridge continuing to the gutter bottom,
a vertical wall continuing to the ridge, and
10 an outward continuous flange being continuously formed along at least the
gutter bottom and the ridge in at least one end in the predetermined direction,
the method comprising:
a firstS4;p in which,
by using a first press-forming apparatus including a first punch, a
15 first die, a first pad, and a second pad, the both pads facing the first punch,
the first pad presses at least a part of a portion to be formed into the
gutter bottom in the forming material to press the forming material against the first
punch in a manner that an end of the forming material continuing to the pmtion to be
formed into the gutter bottom is raised in a direction opposite to the pressing
20 direction and -at least a part of the pmtion to be formed into the gutter bottom is
restrained by the first pad and the first punch, and
the second pad subsequently presses at least a part of an end in the
predetermined direction in a portion to be formed into the ridge against the first
punch in a manner that the end in the predetermined direction continuing to the
25 pmtion to be formed into the ridge is raised in the direction opposite to the pressing
direction and the pmtion to be formed into the ridge is bent in the pressing direction,
51
and simultaneously, at least the part of the pmiion to be formed into the ridge is
restrained by the second pad and the first punch, and
the first ptmch and the first die carry out press forming to form an
intermediate product while the forming material is restrained by the first pad and the
5 second pad; and
a second step in which,
by using a second press-forming apparatus including a second
punch and a second die,
the second punch and the second die press form the intermediate
10 product to form the press formed product.
[Claim 2]
The method for manufacturing a press-formed product according to claim 1,
wherein, in the first ,step, the second pad presses, against the first punch, a portion of
at least 1/3 length of a perimeter of a cross section in the pmiion to be formed into
15 the ridge starting fi-om a border between the pmiion to be formed into the ridge and
the po1iion to be formed into the gutter bottom.
[Claim 3]
The apparatus for manufacturing a press-formed product according to claim
1 or 2, wherein the first pad and the second pad are supported by the first die, and the
20 first pad, the second ·pad, and the first die consecutively press the forming material in
this order while the first die is moved toward the first punch.
[Claim 4]
The method for manufacturing a press-formed product according to any one
of claims I to 3, wherein the press forming in the first step is bending forming.
25 [Claim 5]
The method for manufacturing a press-formed product according to any one
52
of claims I to 3, wherein the press forming in the first step is deep drawing.
[Claim 6]
The method for manufacturing a press-formed product according to any one
of claims I to 5, wherein the press-formed product is a formed product in which at
5 least one of width of the gutter bottom and height of the vertical wall gradually
increases toward an end having the outward continuous flange.
[Claim 7]
A press-forming apparatus used for manufacturing a press-formed product
extending in a predetermined direction, having a substantially gutter-shaped cross
10 section intersecting the predetermined direction, and including
a gutter bottom,
a ridge continuing to the gutter bottom,
a vertical wall continuing to the ridge, and
an outward continuous flange being continuously formed along at least the
15 gutter bottom and the ridge in at least one end in the predetermined direction,
the press-forming apparatus comprising:
a punch;
a die; and
a pad facing the punch, the punch and the die carrying out press forming
20 while a forming material made of a high-tensile steel sheet of 390 MPa or more is
restrained by the pad and the punch,
wherein the pad includes a first pad, and a second pad being different from
the first pad,
the first pad presses and restrains at least a part of a pmiion to be formed
25 into the gutter bottom in the forming material against the punch,
the second pad presses at least a part of an end in a portion to be formed into
53
the ridge against the punch in a manner that the portion to be formed into the ridge is
bent in the pressing direction and at least the part of the portion to be formed into the
ridge is simultaneously restrained, and
the second pad restrains at least the part of the p01iion to be formed into the
5 ridge after the first pad restrains at least a part of the portion to be f01med into the
gutter bottom.
[Claim 8]
The press-forming apparatus according to claim 7, wherein the second pad
presses a p01iion of at least 1/3 length of a perimeter of a cross section in the p01iion
10 to be formed into the ridge starting from a border between the p01iion to be formed
into the ridge and the portion to be formed into the gutter bottom.
[Claim 9]
The press-forming apparatus according to claim 7 or 8, wherein the first pad
and the second pad are supp01ied by the die, and the first pad, the second pad, and
15 the die consecutively press the forming material in this order while the die is moved
toward the punch.