BLANK, FORMING PLATE, PRESS FORMED ARTICLE MANUFACTURING METHOD,
AND PRESS FORMED ARTICLE
DESCRIPTION
Technical Field
[0001] The present invention relates to a blank, a forming plate, a manufacturing method for
a press formed article, and a press formed article.
Background Art
[0002] Automotive body shells include unit construction structures (nlonocoque structures)
in which framework members such as front pillars, center pillars, side sills, roof rails, side
members and the like, are joined together with various formed panels such as hood ridges,
dash panels, front floor panels, rear floor front panels, and rear floor rear panels. Fratnework
members that generally have a closed cross-section, such as front pillars, center pillars, and
side sills, are assembled by joining configuration members such as front pillar reinforcement,
center pillar reinforcement, and side sill outer reinforcement, to other configuration members
such as outer panels and inner panels.
[0003] For example, as illustrated in Fig. 12, a framework member 1 is formed by joining
configuration members 2 to 5 together by spot weldit~g.
[0004] The configuration member 2 has a substantially hat shaped lateral cross-section
profile including a top plate section 2a, a pair of vertical wall sectior~s2 b, 2b extending
downward from either end of the top plate section 2a, and flange sections 2c, 2c extending
outward from lower ends of the vertical wall sections 2b, 2b. The top plate section 2a of the
structural member 2 has an L-shaped external profile in plan view (such a configuration
meniber is also referred to below as an "L-shaped profile comnponent"). The strength and
rigidity of the framework member 1 are secured by including such a configuration member 2.
[0005] Fig. 13 is an explanatory diagram illustrating a configuration member (also
sometimes referred to below as a "T-shaped profile component") 6 including a top plate
section 6a that has a T-shaped external profile in plan view. Similarly to the L-shaped profile
component 2, the T-shaped profile component 6 also has a su~bsta~~tiahlalty shaped lateral
cross-sectiou profile including the top plate section 6a, a pair of left and right vettical wall
sections 6b, 6b, and flange sections 6c, 6c. hire are also Y-shaped profile colnponents (not
illustrated in the drawings), in which the T-shaped profile component 6 has been modified so
as to give the top plate section a Y-shaped external profile in plan view.
[0006] Pressing by drawing is norlnally employed when manufacturing the L-shaped profile
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conlponent 2, tlie T-shaped profile component 6, or the Y-shaped profile component by
pressing, in order to suppress creasing from occurring.
[0007] Fig. 14A is a schematic explanatory diagra~nil lustrating pressing by drawing at a
stage prior to the start of forming, and Fig. 14B is a schematic explanatory diagram
illustrating forming cotnpletion.
[0008] In a drawing method, as illustrated in Fig. 14A and Fig. 14B, a die 7, a punch 8, and
a crease suppresser 9 (blank holder) are employed to press material of a metal plate (a blank)
10 into a press formed article, for example an L-shaped profile component 11, by drawing.
[0009] Fig. 15 is a schematic explanatory diagram illustrating an example of tlie press
fornled article 11 manufactured by pressing using drawing, arid Fig. 16 is a schematic
explanatoly diagram illustrating the blank 10 that is the forming material of the press formed
article 11. Fig. 17 is a schematic explanatory diagram in which a crease suppression region
10a of the blank 10 is illustrated by hatching, and Fig. 18 is a schematic explanatory diagram
illastrating an intermediate press fonned alticle 12 prior to trimming.
[0010] For example, in cases in which the L-shaped profile component 11 illustrated in Fig.
15 is manufactured by a pressing method using drawing, (1) the plate metal material 10
illustrated in Fig. 16 is placed between the die 7 and the punch 8 illustrated in Fig. 14A, (2)
the crease suppression region 10a surrounding the plate metal material 10 as illustrated in Fig.
17 is held firmly in place by tlie crease suppresser 9 and the die 7, (3) as illustrated in Fig.
14B, the die 7 and the punch 8 are moved relative to each other in the pressing direction (the
vertical direction) and the plate metal material 10 is pressed into the intermediate press
formed article 12 illustrated in Fig. 18 by drawing, and (4) unwanted portions surrounding the
intermediate press formed article 12 are trimmed, so as to obtain the L-shaped profile
component 11.
[0011] As illustrated in Fig. 14A, Fig. 14B, and Fig. 15 to Fig. 18, by pressing forming by
drawing, inflow of the blank 10 into the mold can be suppressed by the crease suppresser 9,
thereby enabling the occurrence of creasing due to excessive inflow of the blank 10 to be
suppressed in the intermediate press formed article 12.
[0012] However, in order to tnanufacture the press fornied article 11 by pressing forming by
drawing, a broad trim region is required surrounding the intermediate press formed article 12,
thereby reducing the yield of the press formed article 11 and increasing the manufacturing
cost.
[0013] Fig. 19 is a schematic explanatory diagram illustrating examples of conditions under
which the pressing defects of creasiug and cracking occur in the intermediate press fornled
article 12.
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[0014] As illustrated in Fig. 19, in the intermediate press formed article 12, creasing is liable
to occur at regions a where there is excessive inflow of the blank 10 into the mold during the
drawing process, and cracking is liable to occur at regions where there is localized reduction
in plate thickness during the drawing process. In particulal; when pressing is attempted by
drawing the L-shaped profile component 2 using a high strength steel plate with low ductility
as a blank, creasing and cracking are liable to occur due to ins~ificiendt uctility of the blank
10.
[0015] In order to prevent the occurrence of such creasing and cracking, conventionally a
steel plate that has excelle~ldt uctility but comparatively low strength has been employed as
the blank 10 for the L-shaped profile component 2, such as fiont pillar reinforcenlent or the
like, or for the T-shaped profile component 6, such as center pillar reinforcement or the like.
It has accordingly been necessary to increase plate thickness of the blank 10 in order to secure
strength, making an increase in weight and an increase in cost unavoidable.
[0016] Japanese Patent Application Laid-Open (JP-A) Nos. 2003-103306,2004-154859,
2006-015404, and 2008-307557 (also referred to below as "Patent Documents 1 to 4"
respectively) describe pressing methods using bending to manufacture components with a
simple cross-section profile such as a hat shaped or a Z-shaped profile extending along the
entire length in the.length direction. However, these methods are not applicable to
manufacture of products with complex profiles such as the L-shaped profile component 2, the
T-shaped profile component 6, or a Y-shaped profile component.
[0017] Accordinglj: in pamphlet of International Publication No. 201 11145679 (also refen-ed
to below as "Patent Document 5'7, the present inventors have previously disclosed a patented
invention (specification of Japanese Patent No. 5168429) relating to a method that enables the
L-shaped profile conlponent 2, the T-shaped profile component 6, or a Y-shaped profile
component to be pressed by bending with good yield, and without creasing or cracking
occurring, even lvlvhen a high tensile steel plate with low ductility is employed for the blank.
[0018] Since this patented invention is already known fkom Patent Document 5, it is
explained in brief below. This patented invention is a method to form, from a blank, a
component having a substantially hat shaped lateral cross-section profile and a vertical wall
section including a bent portion forming a protrusion toward a top plate section side in plan
view, such as an L-shaped profile membec A blank is placed between a die, and a pad and a
bending mold, and (1) in a state in which the pad applies pressure to a portion of a location of
the blank corresponding to the top plate section and sewing as an out-of-plane deformation
suppression region, and also in a state in which an end portion of a portion of the blank
corresponding to the L-shape lower side is present in the same plane as the top plate section,
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moving the die and the bending mold relative to each other in a vertical direction so as to
form an L-shaped profile component by forming a vertical wall section and a flange section
while sliding (moving in-plane) the end portion of the portion of the blank col~espondingto
the L-shape lower side over a location of the die corresponding to the top plate section.
Alternatively, (2) the pad is placed in the vicinity or in contact with a portion of the location
of the blank corresponding to the top plate section and sewing as an out-of-plane deformation
suppression region, and in a state in which a gap between the pad and the die is maintained at
fiom the plate thickness of the blank to 1.1 times the plate thickness of the blank, and also in a
state in which the end portion of the blank at the portion corresponding to the L-shape lower
side is present in the same plane as the top plate section, moving the die and the bending mold
relative to each other in a vertical direction so as to form the L-shaped profile component by
forming a vertical wall section and a flange section while sliding (moving in-plane) the end
portion of the blank at the portion corresponding to the L-shape lower side over the location
of the die corresponding to the top plate section of the blank. It1 the present specification,
the method of pressing by bending according to this patented invention is referred to as a "fsee
bending method".
[0019] In the free bending method, in order to press an L-shaped profile component or the
like from a blank, a.location of the blank corresponding to a portion at the L-shape lower side
of the L-shaped profile component is pulled toward the vertical wall section. As a result,
cracking is suppressed due to being able to reduce excessive tensional stress at the flange
section, which is vulnerable to cracking due to a reduction in plate thickness when pressing by
ordinary drawing.
[0020] Moreover, even at the top plate section where creasing is likely to occur due to
excessive inflow of the blank during pressing by normal drawing of the L-shaped profile
conlponent, creasing that occurs due to inflow of the blank is suppressed.
[0021] Moreover, yield is improved since there is no need to provide a large him region to
suppress creasing, sac11 as is always provided at a location of the blank corresponding to a
portion at the L-shape lower side of the L-shaped profile component when pressing by normal
drawing.
[0022] Moreover, since the ductility demanded of the blank for pressing by bending is
reduced, it is possible to employ a steel plate with colnparatively low ductility and high
strength for the blank, as well as a steel plate with excellent ductility and comparatively low
strength. This thereby enables a reduction in the plate thickness of the blank, enabling a
contribution to be made to reducing the weight of a vehicle or the like.
SUMMARY OF INVENTION
Technical Problem
[0023] As described above, a free bending method is a groundbreaking pressing method that
enables cold pressing of L-shaped profile components, T-shaped profile components, or the
like from high strength blanks, at low cost and without cracking and creasing occurring.
[0024] However, as a result of careful investigation by the inventors in order to further
inlprove on the excellent pressing characteristics of the free bending method, new issues
particular to the free bending method have been discovered, namely that when each of the
dimensions of the L-shaped profile component 11, and especially the width w3 of the L-shape
base section of a top plate section 1 la (see Fig. 15), are long, even using the free bcnding
method, cracking occurs at the inside or at edge portions of the L-shaped profile component
11 (at the vicinity of portion A in Fig. 15) at a portion connecting between a vertical wall
section 1 lb and a flange section l l c in a curved portion 14 (also sometimes referred to below
as "flange cracking"), and edge cracking occurs at an L-shape base section of the top plate
section 1 la (the portion B in Fig. 15) (also sometimes referred to below as "top plate edge
cracking").
[0025] As a countermeasure against cracking when pressing using the free bending method,
consideration might be given to, sitnilarly to in other pressing methods that employ bending,
preventing cracking by providing an excess portion of an appropriate size at the edge of a
portion of the blank 10 that will form the flange section llc, thereby letting the material of the
top plate section 1 la move toward the vertical wall section I l b side.
[0026] However, a further issue was uncovered as a result of the inventors' investigations.
Namely, in order to relieve flange cracking in the free bending method, it is undoubtedly
effective to provide an excess portion and increase the range at the edge of the blank 10 at the
portion that will fonn the flange section I lc. I-Iowever, it was discovered that since the
strength of the portion that will form the flange section 1 lc where the excess portion is
provided also increases, the amout~ot f inflow of the blank from the portion of the blatlk 10
that will form the top plate section 1 la to tile portion of the blank 10 that will form the
vertical wall section l l b increases, leading to the top plate edge cracking.
[0027] If, in order to avoid top plate edge cracking, an excess portion is provided to the
portion of the blank 10 that will form the L-shape base section of the top plate section lla:
then the amount of inflow of the blarlk from the top plate section 1 la to the vertical wall
section 1l b becomes insufficient due to increased defor~nationr esistance of the top plate
section I la, leading to flange cracking.
[0028] Paragraph 0058 of Patent Document 5 refers to providing an excess portion of from
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25 mln to 100 mm in cases in which the width of the flange section is less than 25 mm.
However, there is no specific detail regarding the shape of the excess portion. There is also
no description of providing an excess portion in cases in \vllich the width of the flange section
is from 25 mm to 100 nnn.
[0029] Accordingly, there are 110 established techniques for preventi~lgt he occurrence of
flange cracking or top plate edge cracking when using the free bending method to press an
L-shaped profile component, a T-shaped profile component, or moreover a Y-shaped profile
component in which the \vidth w3 at one length direction end of the top plate section lla is
greater than the width wl at the other end due to the presence of the curved portion 14.
Accordingly, for example, when pressing using the free bending method to mallufacture
center pillar reinforcement, this being a typical example of a T-shaped profile component, the
width of one length direction end has to be shortened (the difference in width to the other eud
has to be reduced) in order to prevent flange cracking and top plate edge cracking from
occursing. Accordingly, it has not been possible to set the width of one length direction end
of the top plate sectiou of center pillar reinforcement longer than 300 tnm with press forming
technology.
[0030] An object of the present invention is to provide a blank and a forming plate that
prevent or suppress creasing and cracking during pressing, a press formed article
manufacturing method that prevents or suppresses creasing and cracking during pressing, and
a press formed article in which creasing and cracking have been prevented from occurring.
Solution to Problem
[003 11 Briefly stated, the present invention is based on the technological concept of
"suppressing excessive inflow of the blank from a top plate section to a vettical wall section
so as to enable top plate edge cracking to be prevented from occt~rringw, hile preventing
flange cracking from occurring in the press formed article by devising a way to provide an
excess portion to an edge portion of a portion that will form a flange section in a blank with
an opened-out shape of a press formed article of an L-shaped profile component, a T-shaped
profile component, or moreover a Y-shaped profile component". More specifically, the
present invention is based on the technological concept of "providing an excess portion to an
edge portion of a portion that will form a flange section in a blank with an opened-out shape
of a press formed article of a T-shaped profile component, an L-shaped profile component, or
moreover a Y-shaped profile component, and also providing a first recess, a protrusion, and a
second recess to an edge portion of the excess portion, thereby enabling the occurrence of
flange cracking to be suppressed by the protrusion provided to the excess portion, and
enabling top plate edge cracking to be suppressed from occurring due to being able to reduce
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the amount of displaceinent fiorn the top plate section to the vertical wall section by
straightening out of both the first recess and the second recess provided to the excess portion".
[0032] A first aspect of the present invention provides a flat plate shaped blank for pressing
to manufacture a worked component, the worked conlponent including: a top plate section
including, out of a pair of outer edge portions, at least one outer edge portion that has, in plan
view, a straight-line outer edge poi-tion of a straight line and a curved-line outer edge portion
that is contiguous to the straight-line outer edge portion and that curves in a concave shape so
as to move away from the other outer edge portion toward the ooutside; a vertical wall section
including a flat vertical wall portion that is bent downward fioru the outer edge portion and
that is formed following the straight-line outer edge portion, and a curved vertical wall
portion that is formed following the cui-ved-line outer edge portion; and a flange section
including a straight-line flange portion that extends from the flat vertical wall portion toward
the outside, and that is formed following the straight-line outer edge portion, and a
curved-line flange portion that is formed following the curved-line outer edge portion and that
extends from the cui-ved vertical wall portion toward the outside. Tlie blank includes: an
excess portion provided at a location corresponding to an edge of the flange section in an
opened-out shape of the worked component, with the excess portion formed with a protrusion
forming a protruding shape toward the outside and a first recess and a second recess
respectively forming recess shapes on either side of the protlusion, wherein at least the
protrusion is provided at a location corresponding to an edge of the cullred-line flange
portion.
[0033] Asecond aspect of the present invention provides the blank of the first aspect of the
present invention, wherein the excess portion further includes a straight-line portion forming a
straight line in plan view at at least one out of between the first recess and the protrusion, or
between the protrusion and the second recess.
[0034] A third aspect of the present invention provides a forming plate including the blank
of either the first aspect of the second aspect of the present invention, on which
pre-processing has been performed prior to pressing.
[0035] Afourth aspect of the present invention provides a lnanufacturing method for a press
formed article, the manufacturing method including: a process of placing the blank of either
the first aspect of the second aspect, or the forlning plate of the third aspect, of the present
invention between a die, and a pad and a bending mold; and in a state in which a portion of
the blank, or of the forming plate, that will form an end portion of the top plate section, the
vertical wall section, and the flange section is present in the same plane as a poi-tion of the
blank, or of the forming plate, that will form the top plate section, a process of pressing by
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bending the vertical wall section and the flange sectiori while moving the end portion in-plane
with respect to a location of the die corresponding to the top plate section, by relatively
moving either the die or the bending mold in a direction so as to approach eacli other in a state
in which an out-of-plane deformation suppression region that is part of a portion of the blank,
or of the forniing plate, that will fonn the top plate section is being applied with pressure by
the pad.
[0036] A fifth aspect of the present invention provides a manufacturing method for a press
formed article, the manufacturing method including: a process of placing the blank of either
the first aspect of the second aspect, or the forming plate of the third aspect, of the present
invention, between a die, and a pad and a bending mold; and in a state in which a portion of
the blank, or of the forming plate, that will form an end portion of the top plate section, the
vertical wall section, and the flange section, is present in the same plane as a portion of the
blank, or of the forming plate, that will form the top plate section, a process of pressing by
bending the vertical wall section and the flange section by placing the pad in the vicinity of,
or in contact with, an out-of-plane deformation suppression region that is part of a portion of
the blank, or of the forming plate, that will form the top plate section, and relatively moving
either the die, or the bending mold, in a direction so as to approach each other while
maintaining a gap between the pad and the die of from the plate thickness to 1.1 times the
plate thickness of the blank, or of the forming plate.
[0037] A sixth aspect of the present invention provides the press formed article
manufacturing method of either the fourth aspect or the fifth aspect of the present invention,
wherein, in plan view of the blank or the forming plate, the out-of-plane deformation
suppression region is a region that is on the side of a location that will form the curved-line
outer edge portion from out of regions of the portion that will form the top plate section
divided into two by an extension line of a line that will form the straight-line outer edge
portion, and that is a region that contacts the die.
[0038] A seventh aspect of the present invention provides the press formed article
manufacturing method of any one of the fourth aspect to the sixth aspect of the present
invention, wherein a portion that is an end portion of the blank, or of the forming plate, and
that is present fiirther toward a side that will form the top plate section than the curved-line
outer edge portion out of locations corresponding to the out-of-plane deformation snppression
region of the blank, or of the forming plate, is present in the same plane as a postion that will
form the top plate section.
[0039] An eighth aspect of the present invention provides the press formed a~ticle
manufacturing method of any one of the fourth aspect to the seventh aspect of the present
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invention, wherein the height of the vertical wall section is either 0.2 times the length of the
curved-line outer edge portion or greater, or 20 mm or greater.
[0040] A ninth aspect of the present invention provides the press formed article
manufacturing method of any one of the fourth aspect to the eighth aspect of the present
invention, wherein the vertical wall section and the flange section are fornled by placing the
pad in the vicinity of, or in contact with, a region that is inside a portion of the blank, or of the
forming plate, that will form the top plate section, and that is a region that extends up to at
least 5 nun fro111 the curved-line outer edge portion toward the side that will form the top plate
section.
[0041] A tenth aspect of the present invention provides the press formed asticle
manufacturing method of any one of the fourth aspect to the ninth aspect of the present
invention, wherein the width of the flange section, fiom a central position of the curved-line
outer edge portion to a position separated by 50 mtn or greater frotn an end portion of the
curved-line outer edge portion toward the straight-line outer edge portion side is from 25 mm
to 100 mtn.
[0042] An eleventh aspect of the present invention provides the press formed article
tnanufacturing method of any one of the fourth aspect to the tenth aspect of the present
invention, wherein the maximum radius of curvature of the culved-line outer edge portion of
the top plate section is fsom 5 mm to 300 mtn.
[0043] Atwelfth aspect of the present invention provides the press fornled article
manufacturing method of any one of the fourth aspect to the eleventh aspect of the present
invention, wherein the tensile strength of the blank, or of the forming plate, is fiom 400 MPa
to 1600 M a .
[0044] A thirteenth aspect of the present invention provides a press formed article including:
a top plate section including, oat of a pair of outer edge portions, at least one outer edge
portion that has, in plan view, a straight-line outer edge portion of a straight line and a
curved-line outer edge portion that is contiguous to the straight-line outer edge pottion and
that cntves in a concave shape so as to move away fsom the other outer edge portion toward
the outside; a vertical wall sectior~in cluding a flat vertical wall portion that is bent dow~lward
from the outer edge portion and that is formed following the straight-line outer edge poltion,
and a curved vertical wall poltion that is formed following the curved-line outer edge portion;
and a flange section including a straight-line flange portion that extends from the flat vertical
wall portion toward the outside, and that is formed following the straight-line outer edge
portion, and a curved-line flange portion that is formed following the curved-line outer edge
portion and that extends from the cur\red vertical wall portion toward the outside, wherein the
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width of an end portion of the top plate section on the curved-line portion side is 150 nltn or
greater, and the pressed product is obtained by pressing, with cold bending, material of a
blank having a tensile strength of from 400 MPa to 1600 MPa, or of a forming plate of the
blank on which pre-processing has been performed.
Advantageons Effects of Invention
[0045] Pressing forming the blank or the forming plate of the present invention enables the
occulTeiice of creasing and cracking in the press formed article to be prevented or suppressed.
The press formed article manufacturing method of the present invention enables a press
formed ar-ticle to be manufactured in which the occurrence of creasing and cracking has been
suppressed or prevented. The press formed article of the present invention is one that has
been manufactnred in a desired shape from a high strength blank, with the occurrence of
creasing and cracking suppressed or prevented.
BRIEF DESCRIPTION OF DRAWINGS
[0046] Fig. 1 is a schematic explanatory diagratn illustrating a simplified shape of an
L-shaped profile component that is a press formed article according to an exemplaiy
embodiment of the present invention.
Fig. 2 is a schematic explanatory diagram illustrating an example of dimensions of
relevant portions of an L-shaped profile component according to an exemplary embodiment
of the present invention.
Fig. 3 is a schematic explanatory diagram illustrating a schematic shape of a blank
for an L-shaped profile component according to an exemplaly embodiment of the present
inventiofi.
Fig. 4A is a perspective view illustrating the vicinity of a curved vertical wall portion
of an L-shaped profile component according to an exemplary embodiment of the present
invention.
Fig. 4B is a perspective view illustrating the vicinity of a curved vertical wall portion
of an L-shaped profile component obtained by a manufactusing method according to an
exemplary embodiment of the present invention.
Fig. 5 is a schematic explanatory diagram illustrating an outline of a mold unit
employed during execution of a manufacturing method according to an exemplary
embodiment of the present invention.
Fig. 6A is a cross-section taken along line a-a in Fig. 4B, schematically illustrating
the mold unit illustrated in Fig. 5 prior to the start of pressing.
Fig. 6B is an explanatory diagram of a cross-section taken along line a-a in Fig. 4B,
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schematically illustrating the mold unit illustrated in Fig. 5 upon completion of pressing.
Fig. 6C is a cross-section taken along line b-b in Fig. 4B, schematically illustrating
the mold unit illustl.ated in Fig. 5 prior to the start of pressing.
Fig. 6D is a cross-section explanatory diagram take11 along line b-b in Fig. 4B,
schematically illustrating the mold unit illustrated in Fig. 5 upon complctioli of pressing.
Fig. 7 is a schematic explanatory diagram illustrating an out-of-plane deformation
suppression region (region F) of a blank by hatching.
Fig. 8 is a perspective view illustrating a state in which a blank has been placed on a
die.
Fig. 9 is a perspective view illustrating a state after the blank has been formed into an
L-shaped profile member.
Fig. 10A is a schematic explanatory diagram illustrating the shape of a blank of a
Comparative Example 1.
Fig. 10B is a schematic explanatoly diagram illustrating the shape of a blank of a
Comparative Example 2.
Fig. 10C is a schematic explanatoty diagram illustrating the shape of a blank of a
Comparative Example 3.
Fig. 10D isa schematic explanatory diagram illustrating the shape of a blank of a
Comparative Example 4.
Fig. 10E is a schematic explanatory diagram illustrating the shape of a blank of an
Example.
Fig. 11 is a perspective view illustrating shape of a press formed article that is a
cot~figurationc omponent of a framework component of an automobile produced by the
Example.
Fig. 12 is a schelllatic explanatory diagram illustrating an example of a framework
metnber formed by joining configuration members together by spot welding.
Fig. 13 is an explanatory diagram illustrating a T-shaped profile component in which
a top plate section has a T-shaped external profile in plan view.
Fig. 14Ais a schematic explanatory diagram illustrating pressing by drawing, prior to
the start of forming.
Fig. 14B is a schematic explanatory diagratn illustratitlg pressing by drawing, upon
completion of forming.
Fig. 15 is a schematic explatlatory diagram illustrating an example of a press formed
article tnat~ufacturedb y pressing by drawing.
Fig. 16 is a perspective view illustrating a blank that is material for forming a press
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formed article.
Fig. 17 is a schematic explanatory diagram in \vhich a crease suppl.ession region of a
blank is illustrated by hatching.
Fig. 18 is a perspective view illustrating an intermediate press formed article after
pressing.
Fig. 19 is an explanatory diagram illustrating an example of conditions under which
creasing and cracking occur in an intermediate press formed article when employing a free
bending method.
Fig. 20A is a schematic explanatory diagram illustrating a variation in shape of a
blank according to an exemplary embodiment of the present invention.
Fig. 20B is a schematic explanatory diagram illustrating a variation in shape of a
blank according to an exetnplary embodiment of the present invention.
Fig. 20C is a schematic explanatory diagram illustrating a variation in shape of a
blank according to an exemplary embodiment of the present invention.
Fig. 20D is a schematic explanatoty diagram illustrating a variation in shape of a
blank according to an exemplary embodiment of the present invention.
Fig. 20E is a schetnatic explanatory diagram illustrating a variation in shape of a
blank according to.au exemplaly embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS
[0047] Explanation follows regarding a blank, a press formed article, and a manufacturing
method thereof according to an exemplary embodiment of the present invention, with
reference to Fig. 1 to Fig. 11 and Fig. 20. Note that in the present exemplary embodiment,
"plan view" means viewed along the direction of relative movement between a die and a
bending mold during pressing.
[0048] In the present exemplaly embodiment, an example is given in which the press formed
article is an L-shaped profile component. However, the present invention is not limited to an
L-shaped profile component, and may be similarly applied to press formed articles such as a
T-shaped profile component and a Y-shaped profile component that include both a lateral
cross-section profile described later and a curved portion.
[0049] It is sufficient that the blank is a metal plate suitable for pressing, and the material
properties thereof are not particularly limited. The blank is preferably plate metal suitable
for pressing, such as a steel plate, an aluminum plate,or an alloy plate with main components
of steel or aluminum. In the present exetnplary embodilllent, an example is given in which
the blank is a steel plate.
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[0050] 1. Press foulled article
[0051] Fig. 1 is a simplified explanatory diagram of the shape of an L-shaped profile
component 20, this being an elongated press formed article according to the present
exemplary embodiment. Fig. 2 is an explaiiatory diagram illustrating an example of
dimensions of relevant portions of the press formed article. Fig. 3 is a schematic
explanatory diagram illustrating the shape of a blank 30 of the L-shaped profile component 20
according to the present exemplary embodiment.
[0052] As illustrated in Fig. 1, the L-shaped profile component 20 is an elongated press
formed asticle that is elongated along a length direction (the arrow X direction in Fig. 1 (also
referred to below as the X direction)). The dimension of the L-shaped profile component 20
in the X direction is in a range of from 100 mm to 1400 mm, atid is, for example, 300 mm, as
illustrated in Fig. 2.
[0053] The L-shaped profile component 20 has a substantially hat shaped lateral
cross-section profile, and includes a top plate section 20a with a substantially L-shape in plan
view, two vertical wall sections 20c, 20c extending downward from both ends in a direction
orthogonal to the X direction of the top plate section 20a (the arrow Y direction orthogonal to
the X direction in the present exemplary embodiment (also referred to below as the Y
direction)) of the top plate section 20a, and two flange sections 20d, 20d extending toward the
outside from lower end portions of the two vertical wall sections 20c, 20c. Ridge line
sections 20b, 20b having rounded profile lateral cross-sections are provided between the.top
plate section 20a and tlie vertical wall sections 20c, 20c.
[0054] The top plate section 20a includes outer edge portions 24a, 24b that form boundary
lines with the ridge line sections 20b, 20b at both Y direction end portions of the top plate
section 20a. The outer edge portion 24a includes a straight-line outer edge portion 24al
extending along a straight line in plan view from one X direction (also referred to below as
the "XI direction") end portion, a curved-line outer edge portion 24a2 that is contiguous to
the straight-line outer edge portion 24al and curves so as to form a convex shape protruding
toward the inside in plan view, and that diverges from the outer edge portion 24b on
progression toward the other X direction (also referred to below as tlie "X2 direction"), and a
straight-line outer edge portion 24a3 that is contiguous to the cul-ved-line outer edge portion
24a2 and extends alotig a straight line in plan view. Note that the outer edge portion 24b on
the opposite side is formed by a straight-line outer edge portion having a purely straight line
shape in plan view.
[0055] The top plate section 20a extends along the X direction and has a specific width win
the Y direction. A width wl at ail X1 direction end portion of the top plate section 20a is in
13
a range of fiom 50 rnnl to 200 rnm, and is, for example, 100 mm, as illtistrated in Fig. 2. A
width w3 at an X2 direction end portion of the top plate section 20a is in a range of from 70
mm to 1000 tntn, and is, for example, 200 mm as illustrated in Fig. 2.
[0056] In the L-shaped profile component 20, a "base section of the L" means the X2
direction end portion 25 of the top plate section 20a, as illustrated in Fig. 1. In cases such as
in the present exemplary embodiment, in which the end portion is formed from plural pol-tions
in plan view (two straight lines in the present exenlplary embodiment), all of these portions
are included.
[0057] Next, explanation follows regarding the vertical wall sections 20c, 20c.
[0058] The vertical wall section 20c on the outer edge portion 24a side includes a straight
vertical wall portion 20cl following the straight-line outer edge portion 24al and forming a
straight line shape from the XI direction end portion in plan view, a curved vertical wall
portion 20c2 following the curved-line outer edge portion 24a2 and forming a curved shape
that is convex so as to protrude toward the inside in plan view, and a straight vertical wall
postion 20c3 following the straight-line outer edge pottion 24a3 and forming a straight line
shape in plan view. Note that the vertical wall section 20c on the opposite side is formed
fiom a veltical wall section with a purely straight line shape in plan view.
[0059] The height of the vertical wall sections 20c, 20c is in a range of from 20 mm to 120
mm, and is, for example, 70 mm as illustrated in Fig. 2. If the height of the vertical wall
section 20c is below 0.2 times the length of the curved-line outer edge portion 24a2, or below
20 mnl, creasing of the vertical wall section 20c is liable to occur. The height of the vertical
wall section 20c is accordingly preferably 0.2 times the length of the curved-line outer edge
portion 24a2 or greater, and also 20 mm or greater.
[0060] The maximum radius of curvature of the vertical wall section 20c (curved vertical
wall portion 20c2) in plan view, namely the maximum radius of curvature of the outer
edge portion 24a (curved-line outer edge portion 24a2), is preferably from 5 mm to 300 rnm.
If the maximum radius of curvature is less than 5 tnm, a maximum curvature portion juts out
locally and is therefore vulnerable to cracking. If the maximum radius of curvature is
greater than 300 mm, then a large difference arises between the width ~v3of the X2 direction
end portion of the top plate section 20a and the width wl of the X1 direction end portion, and
the pulling distance into the vertical wall section 20d during pressing increases, giving a large
distance of sliding between a mold unit 40, which will be described later, and the blank 30,
exacerbating abrasion of the mold unit 40 and reducing the mold lifespan. The maximum
radius of curvature of the curved vertical wvall portion 20c2 (curved-line outer edge portion
24a2) is thus preferably 100 mnl or below.
14
[0061] Next, explanation follows regarding the flange sections 20d, 20d.
[0062] The flange section 20d on the outer edge portion 24a side includes a straight-line
flange portion 20dl following the outer edge portion 24a and with an edge fro111 the Xl
direction end portion for~ninga straight line shape in plan view, a curved-line flange portion
20d2 in a curved shape having an edge indented toward the inside, and a straight-line vertical
wall portion 20d3 fornling a straight line shape. Note that the flange section 20d on the
opposite side is formed fiom a straight-line flange portion with a purely straight line shape in
plan view.
[0063] The two flange sections 20d, 20d both have a width in a range of fiom 10 mm to 100
Inm, for example 35 mm, as illustrated in Fig. 2.
[0064] 1x1 the manufacturing method according to the present exemplary embodiment, as
illustrated in Fig. 4A, the width hi of the flange section 20d at a side further toward a first end
portion A than the center C of the curved vertical wall portion 20c2 (meaning at the end point
of the curved vertical ~ralpl ortion 20c2 on the X1 direction side) may be from 25 mm to 100
mm. More specifically, pressing is preferably performed such that the width hi of the flange
section 20d is from 25 mm to 100 mm in the section D in Fig. 4A, which will be described
later, spanning from the center line C of the flange section 20d, past the flange section 20d at
the end portion A, and up to a position 50 mnm away from the flange section 20d along the
flange peripheral direction on the end portion A side.
[0065] The width hi of the flange section 20d is defined as the distance of the flange section
20d in a direction oitl~ogonatlo a tangent at a freely selected position of an edge of the flange
section 20d.
[0066] If there are locations where the flange width hi of the flange section 20d in tl~c
section D is below 25 mm, a reduction in plate thickness at the flange section 20d becomes
large, and cracking is liable to occur. This is due to force pulling the X2 direction end
portion of the top plate section 20a (the vicinity of portion B in Fig. 1) into the vertical wall
section 20c becoming concentrated in the vicinity of the flange section during the fornling
process.
[0067] If there are locations where the flange width hi of the flange section 20d in the
section D exceeds 100 mm, then the flange section 20d is compressed by a large amount, and
creasing is liable to occut
[0068] Accordingly, the occurrc~~ocfe creasing and cracking in the flange section 20d can be
suppressed by setting the flange width hi of the flange section 20d in the section D from 25
mm to 100 mm.
[0069] Accordingly, when manufacturing a component \vit11 a shape in ~vlvhicht he flange
15
width hi of the flange section 20d is less than 25 mnl, an intermediate pressed body having a
flange section 20d of width 25 111111 or greater is preferably nianufactured by pressing, with the
unwanted portion then being trimmed off.
[0070] For convenience, the L-shaped profile component 20 is divided into a first portion 21
and a second portion 22 at an X direction boundaiy position between the straight-line outer
edge portion 24al and the curved-line outer edge poition 24a2. In the first poition 21, the
vertical wall sections 20c, 20c are formed with parallel straight line shapes in plan view, such
that the width wl of the top plate section 20a is substantially uniforn~.
[0071] On the other hand, in the second pol-tion 22, out of the vertical wall sections 20c, 20c,
the cui-ved vertical wall poition 20c2 (curved-line outer edge portion 24a2) curves
substantially toward the plate thickness direction, such that the width w of the top plate
section 20a gradually increases on progressio~to~w ard the X2 direction end portion, thereby
giving the top plate section 20a a substantially L-shape in plan view. The radius of curvature
of the curved veitical wall portion 20c2 is in a range of from 5 mn to 500 mm, and is, for
exan~ple2, 00 mm as illustrated in Fig. 2.
[0072] Note that the curved-line outer edge portion 24a2, the curved vertical wall portiot~
20c2, and the curved-line flange section 20d2 are also collectively referred to as a curved
portion 23.
[0073] In plan view, the curved-line outer edge poition 24a2 of the L-shaped profile
component 20 may have a profile with a uniform curvature, an elliptical profile, a profile
including plural curvatures, or a profile iucluding a straight-line portion. Namely, in tlie
L-shaped profile component 20, in plan view the top plate section 20a is present to the outside
of the curved arc shape of the ridge line section 20b (curved-line outer edge portion 24a2),
and the flange section 20d is present at the inside (the arc center side) of the curved arc shape
of the ridge line section 20b. Note that the top plate section 20a does not need to be a
perfectly flat face, and various additional shapes (such as recesses or protix~sions)m ay be
imparted to the top plate section 20a according to the design of the press formed article.
[0074] As illustrated in Fig. 4A, out of tlie two end poitions of the ctui-ved-line outer edge
portion 24a2 of the L-shaped profile component 20, the X1 direction end portion is referred to
as the end portion A (first end portion), and the X2 direction end portion is referred to as the
end poition B (second end portion).
[0075] At1 example is illustrated in which the width w3 of the X2 direction end poltion of
the top plate section 20a is 150 tnm or greater. Hitherto, when manufacturing center pillar
reinforcement, this being a typical example of a T-shaped profile component, by pressit~g
usiug the free bending method, it has been necessary to modify the shape of the blank in order
16
to prevent the occurrence of flange cracking and top plate edge cracking, and it has been
difficult to set the width w3 at a base section of the center pillar reinforcen~entg reater than
150 mni. However, the L-shaped profile conlponent 20 according to the present exemplary
enlbodiment is formed using the free bending method enlploying the blank 30, described latel;
rendering modification of tlie shape of tlie blank in order to prevent the occurrence of flange
cracking and top plate edge cracking unnecessary, and enabling a width w3 of 150 tnrn or
greater to be secured for the X2 direction end poltion of the top plate section 20a.
[0076] Aportion of the second portion 22 including the X2 direction end portion configures
a joint portion with other members (for example a roof rail or a side sill), and joining to the
other members though this portion is performed by appropriate means (such as spot welding
or laser welding).
[0077] The press formed article 20 according to the present exempla~ye mbodiment
accordingly enables an increase in the joint surface area of the portion configuring the joint
portion with other members, and enables the joint strength with the other members to be
raised. Increased bending rigidity and increased twisting rigidity of the automotive body
shell is enabled when the press formed article is an automotive vehicle body configuration
member (such as various pillar outer reinforcements or sill outer reinforcenlents).
[0078] The above explanation similarly applies to cases in which one of the vertical wall
sections 20c out of the two vertical wall sections 20c, 20c, and the ridge line section 20b and
flange section 20d that are connected to this vertical wall section 20c, all curve substantially
to\vard the plate thickness direction of the vertical wall section 20c, namely, to use the
example of the L-shaped profile component 20, in cases in which both of the vertical wall
sections 20c out of tlie two vertical wall sections 20c, 20c, and the ridge line sections 20b and
flange sections 20d respectively connected to these vertical wall sections 20c, all curve
substantially toward the plate thickness direction of the vertical wall section 20c. Namely,
the above explanation similarly applies to T-shaped profile components and Y-shaped profile
components.
[0079] The L-shaped profile component 20 that is a press formed article according to the
present exemplary embodiment is configured as described above.
[OOSO] 2. Blank
[008 11 Next, explanation follows regarding the blank 30, this being a plate metal material
for pressing the L-shaped profile component 20.
[0082] As illustrated in Fig. 3, the blank 30 is manufactured by cutting a specific shape out
of a steel plate material using an appropriate method (such as laser cutting).
[0083] Pre-processing performed on the blank 30 includes, for example, bending to form
17
light protrusio~isin the il~terioro f the blank 20, pressing by drawing, arid hole cutting. Such
pre-processing lnay be perforlned on the blank 30 as appropriate in consideration of the
dimensions and shape of tlie press formed article 20.
[0084] The blank 30 is configured with a shape 31 of the press formed article 20 as it is
opened-out (the shape illustrated by single-dotted intermittent lines in Fig. 3, also sometimes
referred to as the "opened-out shape" in the present specification), namely a shape combining
a portion 30a that will form the top plate section 20a, portions 30b, 30b that will form the
outer edge portions 24a, 24b, and portions 30c, 30c that will form the ridge liue sections 20b,
20b, the vertical wall sections 20c, 20c, and the flange sections 20d, 20d, to which a bulging
portion 48 is additionally provided at an edge of a portion that will form the flange section
20d including the curved-line flange portion 20d2. An edge of the bulging portion 48 is
corifigured by an excess portion 32 provided with a first recess 33, a protrusion 34, and a
second recess 35 that satisfy Condition 1, described below.
[0085] As illustrated in Fig. 3, an edge portion 45 of the portion of the opened-out shape 3 1
that will form the flauge section 20d is formed, from the XI direction end portion, with a
straight-line edge portion 45a, a curved-line edge portion 45b, and a straight-line edge portion
45c, similarly to the flange section 20d of the L-shaped profile component 20.
[0086] Condition I: Takiqga curvature ill a directiori toward tlie inside of the blank 30 as
having a negative sign, and taking a curvature in the opposite direction to toward the inside of
the blank 30 as having a positive sign, the first recess 33 with a negative sign curvature, the
protrusion 34 with a positive sign curvature, aud the second recess 35 with a negative sign
curvature are formed in this sequence along the edge of the excess portion 32.
100871 The blank 30 preferably also satisfies Conditiotis 2 and 3 below.
[0088] Condition 2: In plan view, the edge length of the protrusion 30 (edge lengths in
plan view are sometilnes also referred to below as "edge lengths") is the edge leugth of the
curved-line edge portion 45b or shorter. The prot~usiou3 4 is provided in order to prevent
flange cracking, and, since it is the curved-line flange portion 20d2 where flalige cracking is
liable to occur, tlie edge length of the protrusion 34 is preferably the edge length of the
curved-line edge portioll 45b or shorter.
[0089] Note that in the blank 30, "plan view" means as viewed alotig a directio~oi rthogonal
to the extension directioli of the plate.
[0090] The edge lengths of the first recess 33, the protrusion 34, atid the second recess 35
refer to the distance betweell inflection points on the edge of the blank 30.
[0091] Conditiori 3: The absolute values of the respective curvatures of the first recess 33
and the second recess 35 are both 0.1 (Ilmm) or below. The first recess 33 and the second
18
recess 35 are provided in order to prevent top plate edge cracking, and the first recess 33 and
the second recess 35 straighten out and suppress inflow of the blank 30 into the mold during
pressing. Accordingly, if the absolute values of the respective curvatnres of the first recess
33 and the second recess 35 are large, stress concentration occurs at the first recess 33 and the
second recess 35 respectively, aud edge cracking is liable to occur at the first recess 33 and
the second recess 35 respectively. Accordingly, the absolute values of the respective
curvatnres of the first recess 33 and the second recess 35 are preferably set to 0.1 (llmm) or
below.
[0092] The opened-out shape 3 1 is the shape on which the shape of the blank 30 is based,
and is the shape of the top plate section 20a, the ridge line sections 20b, 20b, the vertical wall
sections 20c, 20c, and the flange sections 20d, 20d as opened out flat. The opened-out shape
3 1 is the shape obtained by adding, to the portion that will form the top plate section 20a,
portions that will form the ridge line sections 20b, 20b, portions that will form the vertical
wall sections 20c, 20c, and portions that will form the flange sections 20d, 20d.
[0093] As described above, the excess portion 32 is a portion that is the basis for preventing
flange cracking and top plate edge cracking, and the range and size for forming the excess
portion 32 may be decided from these perspectives. For example, an excess portion 32
having a width (the distance fioln a boundary line between the vertical wall section 20c and
the flange section 20d, to the edge of the excess portion 32) of fiom 112 to 312 times the
height of the vertical wall section 20c of the L-shaped profile component 20 product is
preferably formed at the portion that will form the curved-line flange portion 20d2 of the
L-shaped profile component 20. This is to prevent fluctuations in the excess portion 32
according to the shape (length) of the flange section 20d of the L-shaped profile cotnponent
20. Flange cracking occurs if the width of the excess portion 32 is less than 112 the height of
the vertical wall section 20c, and flange creasing and vertical wall cracking occur if the width
of the excess portion 32 exceeds 312 of the height of the vertical wall section 20c.
[0094] In the manufacturing method according to the present exemplary embodiment, a
reduction in the plate thickness of the flange section 20d during forming is suppressed,
thereby enabling good pressing to be achieved not only when employing the blank 30
configured from a steel plate with high ductility and comparatively low strength (for example,
a steel plate with tensile strength of approximately 400 MPa), but also when employing
blanks configured fiom a steel plate with low ductility and comparatively high strength (for
example, a steel plate with tensile strength of approximately 1600 MPa). This thereby
enables high strength plate steel with a tensile strength from 400 MPa to 1600 MPa to be
employed for the blank 30.
19
[0095] An X2 direction end portion 30d of the blank 30 preferably has a shape in which at
least a portion of the end portion is disposed in the same platle as tlie portion 30a that will
form the top plate section 20a, natnely preferably has a shape in which the end portion
remai~lsu naffected during pressing. Moreovel; as illustrated in Fig. 7 described later, out of
the blank 30, the end portion at a location corresponding to an out-of-plane defornlation
suppression region (region F) is preferably in the same plane as the portion 30a. In other
words, a portion of the blank 30 that is an end portion of the blank 30 and that is present
further to the side that will form tlie top plate section 20a than a portion that will form the
curved-line outer edge portion 24a2 and the straight-line outer edge portion 24a3 in a location
corresponding to the out-of-plane deformation suppression region, is preferably present in the
same plane as the portion that will form the top plate section 20a.
[0096] In contrast to the blank 30 illustrated in Fig. 3, a straight-line portion may be present
at one or both locations out of between the first recess 33 and the prot~~~s3i4o,n a nd between
the second recess 35 and the protrusion 34 (see the straight-line portions 46,47 in Fig. 20E).
Accordingly, it1 cases in wl~iclsi mall respective radii sufice for the curvature of the first
recess 33, the protrusion 34, and the second recess 35, the excess portion 32 may be formed
so as to include desired edges of the first recess 33, the protrusion 34, and the second recess
35, without the need to employ Jqge radii of curvature, with this being preferable.
[0097] Note that there are various conceivable layouts for the excess portion 32 provided to
the blank 30, as illustrated in Fig. 20A to Fig. 20E.
[0098] As illustrated in Fig. 20A, conceivable blanks 30 include a blank 30 in which the first
recess 33, the protrusion 34, and the second recess 35 of the excess portion 32 are all provided
within the range of the cu~ved-linee dge portion 45b (see Fig. 20A), a blank 30 in which the
start point of the first recess 33 is at a straight-line edge portion 45a (see Fig. 20B), and a
blank 30 in which the start poitit of the second recess 35 is at a straight-line edge portion 45c
(see Fig. 20C).
[0099] Moreover, a blank 30 is conceivable in which the first recess 33 is formed to the
straight-line edge portion 45a, the protrusion 34 is formed to the cul-ved-line edge portion 45b,
and the second recess 35 is formed to the straight-line edge portion 45c (see Fig. 20D).
[0100] Moreover, a blank 30 is cotlceivable in which the straight-line portions 46, 47 that are
straight line shaped in plan view are formed between the first recess.33 and protrusion 34, and
between the protrusiotl34 and the second recess 35 (see Fig. 20E). These are merely
exatnples, and there is no limitation thereto.
[0101] 3. Monl&~ctzrr.in~1g\4 ethod of Press.fir.~n~aedrt icle Accorclinling to Present Exennq~lory
Enn~bodinn~en~t
20
[0102] Regarding the manufacturing metl~odo f the press formed asticle according to the
present exemplary embodiment, first, explanation follows regarding the fiee bending method,
followed by explanation regarding operation and advantageous effects when this is applied to
the blank 30 according to the present exenlplary embodiment.
[0103] Briefly stated, the press formed article manufacturing method is one in which the
press formed article 20 according to the present invention, as described above, is
mat~nfacturedb y pressing the blank 30 according to the present invention as described above
using cold bending that employs the free bending method described in Patent Document 5.
Since the free bending method is already knowvn though Patent Document 5, simplified
explanation is given below.
[0104] The free bending method explained here enlploys an L-shaped profile cotnponent
20Y and a blank 30Y that are shaped differently to the L-shaped profile component 20 and the
blank 30 employed in the above explanation; however, there is no change to the operation and
the like. Moreover, configuration elements of the L-shaped profile component 20Y and the
blank 30Y that are configuration elements similar to those of the L-shaped profile component
20 and the blank 30 are allocated the same reference numerals, and detailed explanation
thereof is omitted.
[0105] Fig. 4B is a perspective view of the curved portion 23 of the L-shaped profile
component 20 obtained by the present manufacturing method. Fig. 5 is a schematic
explanato~yd rawing of the mold unit 40 employed to carly out the present matlufacturing
method. Fig. 6A and Fig. 6B are cross-sections taken along line a-a in Fig. 4B, and
schelnatically illustrate respective states prior to starting pressing, and on co~npletiono f
pressing, using the mold unit 40 illustrated it1 Fig. 5. Fig. 6C and Fig. 6D are cross-sections
taken along line b-b in Fig. 4B, and schematically illustrate respective states prior to starting
pressing, and on cotnpletion of pressing, using the mold unit 40 illustrated in Fig. 5.
[0106] Firstly, explanation follows regarding the mold unit 40, with reference to Fig. 5.
The mold unit 40 includes a die 41 on which the blatlk 30Y is placed, a pad 42 that is
disposed on the other side of the blank 30 to that of the die 41, and a bending mold 43 that
presses the blank 30 by moving relative to the die 41.
[0107] A drive mechanism of the pad 42 may employ springs or hydraulics in cases in which
the blank 30 is applied with pressure to an extent that pennits in-plane movetnent of locations
corsesponding to the out-of-plane deformation suppression region (region F), described later,
and the like. The pad 42 may also be configured by a gas cushion.
[0108] The drive mechanism of the pad 42 may be an electsic cylinder or a hj~draulics ervo
when employed in cases in which the vertical wall section 20c and the flange section 20d are
21
formed in a state in w11ich a gap between the pad 42 and the die 41 at a portion in the vicinity
of, or co~ltactingt,h e out-of-plane defortnation suppression region (region F) is maintained at
a gap from the plate thickness of the blank 30 to 1.1 times the plate thickness of the blank 30.
Note that the up-down positional relationship of the die 41 and the bending mold 43 may be
inverted.
[0109] In this method, the vertical wall section 20c and the flange section 20d are formed in
a state it1 which it is possible for a region of at least a portion of the blank 30Y (at least a
portion of a region of the blank 30 correspondi~~tog the top plate section 20a) to slide (move
in-plane) over a location of the die 41 corresponding to the top plate section 20a. Namely,
the vertical wall section 20c and the flange section 20d are formed by placing the blank 30Y
between the die 41, and the pad 42 and bending ~nold4 3, and at least a portion of the blank
30Y is slid over the location of the die 41 corresponding to the top plate section 20a in a state
in which the pad 42 is in the vicinity of, or in contact with, the blank 30Y.
[0110] Note that "a state in which the pad 42 is in the vicinity of the blank 30Y" means a
state in which the blank 30Y and the pad 42 do not contact each other when the blank 30Y
slides over the location of the die 41 corresponding to the top plate section 20a, but the blank
30Y and the pad 42 do contact each other if the blank 30Y attempts to deform (or buckle)
out-of-plane above this location. More strictly speaking, "a state in which the pad 42 is in
the vicinity of the blank 30Y" means a state in which the gap between the pad 42 and the die
41 is maintained at greater than 1.0 times the plate thickness of the blank 30Y, up to and
including 1.1 times the plate thickness of the blank 30Y
[Olll] When forming the vertical wall section 20c and the flange section 20d, forming may
be performed in a state in which the gap between the pad 42 and the die 41 at a poltion where
the pad 42 is in the vicinity of, or in contact with, the out-of-plane deformation s~~ppression
region (region F) that is a portion of the blank 30Y, is maintained at greater than 1.0 times the
plate thickness of the blank 30Y, and up to and including 1 .I times the plate thickness of the
blank 30Y.
[0112] For example, in cases in which forming is performed in a state in \vhich the gap
between the pad 42 and the die 41 at the portion corresponding to the top plate section 20a is
maintained at from the plate thickness of the blank 30Y to 1.1 times the plate thickness of the
blank 30Y, excessive surface pressure does not act on the blank 30Y, thereby enablit~gth e
blank 30Y to slide (move in-plane) sufficiently withit1 the mold unit 40 during pressing.
Moreover, as forming progresses, if excess has arisen in the top plate section 20a and a force
acts to cause out-of-plane defonnation of the blank 30Y, out-of-plane defor~natioao f the
blank 30Y is restricted by the pad 42, thereby enabling the occurrence of cracking and
22
creasing to be suppressed.
[0113] In cases in which forming is performed with a gap between the pad 42 and the die 41
at the portion corresponding to the top plate section 20a of less than the plate thickness of the
blank 30Y, excessive surface pressure acts between the blank 30Y and the die 41, such that
the blank 30Y cannot slide (~novein -plane) sufficiently in the die 41, leading to cracking of
the flange section 20d.
[0114] However, in cases in which forming is performed with the gap between the pad 42
and the die 41 at the portion corresponding to the top plate section 20a maintained at 1.1 times
the plate thickness of the blank 30Y or greatel; out-of-plane deformation of the blank 30Y is
not sufficiently restricted during pressing, and as forming progresses, not only does obvious
creasing occur in the top plate section 20a due to far too much of the blank 30Y remaitling at
the top plate section 20a, but buckling also occurs, such that forming into a specific shape can
no longer be achieved.
[0115] In cases in which a portion of a metal plate having a tensile strength of from 200
MPa to 1600 MPa, such as is generally employed in automobile components and the like, is
formed in a state in which a gap between the pad 42 and the die 51 is maintained at greater
than 1.0 times the plate thickness of the blank 30Y and up to 1.1 times plate thickness of the
blank 30Y, at a portion of the pad 42 that is it1 the vicinity of, or in contact with, the
out-of-plane deformation suppression region, as the out-of-plane deformation suppression
region (region F), the gap between the pad 42 and the die 41 is more preferably set at fiom the
plate thickness to 1.03 times the plate thickness since slight creasing occurs when the gap
between the pad 42 and the die 41 is 1.03 times the plate thickness of the blank 30Y or
greater.
[0116] In the manufacturing method according to the present exemplary embodiment, as
illustrated in Fig. 6A and Fig. 6B, the vertical wall sections 20c, 20c and the flange sections
20d, 20d are formed at the position of the cross-section on line a-a by placing the portion that
will form the top plate section 20a (see the poi-tion 30a that will forin the top plate section 20a
in Fig. 3) on the die 41, and placing the pad 42 so as to hold down or be in the vicinity of this
portion while pressing both sides of the blank 30 with the bending mold 43. When this is
performed, as illustrated in Fig. 6C and Fig. 6D, the vertical wall section 20c and the flange
section 20d are formed at the position of the cross-section on line b-b by placing a portion
corresponding to the out-of-plane deformation suppression region F on the die 41, and
pressing only one side of the blank 30 with the bending mold 43.
[0117] In this manner, at the cross-section on line b-b, only one side of the out-of-plane
deformation suppression region F is press formed by the bending nlold 43, and since the blank
23
30Y is placed between the pad 42 and the die 41 so as to be capable of moving, a suffieieat
amount of the blank flows into the mold.
[OllX] In the above explanation of the free bending method, a gap is provided between the
pad 42 and tlie die 41. However, the pad 42 may also apply pressure to the blank 30Y.
[0119] Namely, when forming the vertical wall section 20c and the flange section 20d, the
pad 42 may apply pressure to a portion of tlie blank 30Y serving as the out-of-plane
deformation suppression region (region F) with a specific load pressure.
[0120] Cracking occurs in the flange section 20d in eases in which, for example, the pad
load pressure is set high, and, during pressing of the blank 30Y, the portion where the die
mold 41 contacts the top plate section 20a is unable to slide (move in-plane) sufficiently
between the die 41 and the pad 42.
[0121] Creasing occurs in the top plate section 20a in cases in which the load pressure of the
pad 42 is set low, and, during pressing of the blank 30Y, out-of-plane deformation cannot be
restricted at the portion where the die 41 contacts the top plate section 2023.
[0122] In eases in which a steel plate having a tensile strength of from 200 MPa to 1600
MPa, such as is generally employed in automobile components and the like, is formed, if the
blank 30Y is applied with pressure by the pad 42 at a pressure of 30 MPa or greater, cracking
occurs in the flange section 20d due to the blank being unable to slide (move) sufficiently
above the location of the die 41 corresponding to the top plate section 20a. On the other
hand, if pressure of 0.1 MPa or lower is applied then out-of-plane deformation ea~ulobt e
sufficiently suppressed at the top plate section 20a. It is therefore desirable that the pressure
applied to the blank 30Y by the pad 42 is fso~n1 MPa to 30 MPa.
[0123] Moreovel; when the presses and mold units generally employed in automobile
component manufacture are considered, at 0.4 MPa or lowel; stable pressure application with
the pad 42 using a gas cushion or the like becomes difficult, due to this being a small load,
and at 15 MPa or greatel; high pressure press equipment that pushes up the facility cost is
required, due to this being a large load. It is therefore desirable that pressure application by
the pad 42 is performed at a pressure of from 0.4 MPa to 15 MPa.
(01241 Here, pressure refers to the average surfdee pressure when the pressing force applied
by the pad is divided by the surface at-ea of the contact portion between the pad 42 and the .
blank 30Y, and a certain amount of localized variation may be present.
[0125] Fig. 7 is an explanatory diagram in which the out-of-plane deformation suppression
region (region F) of tlie blank 30Y is illustrated by hatching.
[0126] As illustrated in Fig. 7, when forming the vertical wall section 20e and the flange
section 20d, in plan view of the top plate section 20a, out of regions of the top plate section
24
20a divided into two by the tangent to the boundaly line between the ridge line section 20b
and the top plate section 20a at the end portion A (first end portion), this being the one end
portion of the arc shaped curving locations 20b of the ridge line section 20b, the region on the
side including the end portion B (second end portion), this being the other end portion, that is
the region that contacts the top plate face of the die 41 (the face of the blank 30 corresponding
to the pol-tion 30a that will form the top plate section 20a) (the hatched poltion in Fig. 7) is
preferably applied with pressure as the out-of-plane deformation suppression region (region
F). This thereby enables creasing to be suppressed from occul~ingin the top plate section
20a and the vertical wall section 20c.
[0127] When applying pad pressure, the pad employed preferably has a shape covering the
entire poltion of the blank 30 that contacts the top plate face of the die 41, or with a shape that
covers part of the portion of the blank 30 that contacts the top plate face of the die 41 and
includes the entire out-of-plane deformation suppression region (region F). However, for
example in cases in which an additional shape has been added to the out-of-plane deformation
suppression region (region F) according to the design of the product, a pad may be employed
with a shape that avoids the additional shape portions, that at least includes a region of the
out-of-plane deformation suppression region (region F) that extends up to at least 5 mm from
the position that will form the outer edge portion 24a (the curved-line outer edge portion 24a2,
the straight-line outer edge portion 24a3), and that covers 50% or greater of the surface area
of the out-of-plane defornlation suppression region (region F). Apad with a segmented
pressure application face may also be employed.
[0128] 111 the blank 30, the region that ~vilflo rm the top plate section 30a and that extends up
to at least 5 rnm from the position that will form the outer edge portion 24a is preferably
applied with pressure by the pad 42. Namely, the curved vertical wall portion 20c2 and the
curved-line flange portion 20d2 are preferably formed by placing a region that is on the inside
of the pol-tion 30a of the blank 30 that will form the top plate section 20a and that extends up
to at least 5 mm from the position that will form the outer edge portion 24a, in the vicinity of,
or in contact with, the pad 42. For example, creasing is liable to occur in the top plate
section 20a if the pad 42 o~ilyap plies pressure to a region that extends up to at least 4 mn
from the outer edge poltion 24a.
[0129] Fig. 8 is a perspective view illustrating a state in which the blank 30Y has been
placed on the die 41. Fig. 9 is a perspective view illustrating a state after the blank 30Y has
been formed into the L-shaped profile member 20Y.
[0130] In the manufacturing method according to the present invention, as illustrated in Fig.
8, the blank 30Y is placed on the die 41, and, in a state in which the pottion 30a that will form
25
the top plate section 20a of the L-shaped profile lneniber 20Y is applied m~ithp ressure toward
the die 41 by the pad 42, the bending niold 43 is then lowered in the pressing direction, and
the vertical wall sections 20c, 20c and the flange sections 20d, 20d are formed as illustrated in
Fig. 9.
[013 11 As described above, the blank 30 is deformed so as to follow the shape of the vertical
wall section 20c and the flange section 20d by lowering the bending mold 43 in the pressing
direction. When this is perfomled, a location of the blank 30 corresponding to the end
portion 30d flows into the vertical wall section 20c. Namely, due to the position on the
blank 30 of tlie end portion 30d that will form the flange section 20d straightening out, the
occurrence of creasing in the top plate section 20a, arising in conventional drawing due to too
much of the blank 30 flowing into the mold, is suppressed. Moreover, due to the position on
tlie blank 30 of the end portion 30d corresponding to the flange section 20d not undergoing
excessive stretching, the occurrence of cracking in the flange section 20d, which is vulnerable
to cracking due to a reduction in plate thickness in conventional drawing, is suppressed.
Due to being able to suppress the occurrence of creasing and cracking in this manner, there is
no need to provide a large trim region in the vicinity of the end portion 30d of the blank 30,
which is needed in order to prevent creasing in conventional methods.
[0132] The press formed a k l e manufacturing method according to the present exemplary
embodiment is a method for manufacturing from the blank 30 by cold pressing using the
above free bending method.
[0133] Accordingly, applying the blank 30 in place of the blank 30Y results in obtaining the
following operation in addition to exhibiting operation and advantageous effects similar to
those of the free bending method described above.
[0134] In this manufacturing method, when performing pressing by bending, the blank 30
includes the first recess 33, the protrusion 34, and the second recess 35 at the edge portion of
the excess portion 32, thereby increasing the amount of the blank that flows into the mold
fiom the protrusion 34 provided to the excess portion 32, and enabling the occurrence of
flange cracking to be suppressed. Both the first recess 33 and the second recess 35 that are
respectively provided oneither side of the protrusion 34 in the excess portion 32 straighten
out during pressing, thereby enabling a reduction it1 the amount of displacement from the
portion 30a that will form the top plate section 20a toward the vertical wall section 30c, and
enabling cracking at the top plate edge to be suppressed from occurring.
[0135] In this manufacturing metllod, the blank 30 employed in pressing using such bending
includes the first recess 33, the protrusion 34, aud the second recess 35 at the edge portion of
the excess portion 32, making it possible not only to suppress flange cracking from occurring
26
using the protrusion 34 provided to the excess portion 32, but also enabling a reduction in the
amount of displacement fiom the portion 30a that will form the top plate section 20a toward
the vertical wall section 30c due to the first recess 33 and the second recess 35 provided to the
excess portion both straightening out, thereby enabling the occurrence of top plate edge
cracking to be suppressed, even in cases in which the L-shaped profile component 20 is set
with a long width w3.
[0136] The following tests were performed in order to confirm the operation of the excess
portion 32.
[0137] Namely, as illustrated in Fig. 1OA to Fig. lOE, press formed articles 20 with the shape
and dimensions illustrated in Fig. 1 and Fig. 2 were manufactured using the various shaped
blanks 36 to 39, and 30 (Comparative Examples 1 to 4, Example) (tensile strength 1180 MPa,
plate thickness 1.6 mm), by holding down the portion of the blank that will form the top plate
section 20a with a pad, and then employing the free bending method to bend wit11 a bending
forming.
[0138] Note that the blanks 36 to 39,30 are the same as each other, except for in the excess
portion 32.
[0139] Fig. 1OA illustrates the blank 36 (Comparative Example l), this having an
opened-out shape based on the L-shaped profile component 20. Fig. 10B to Fig. 10E each
illustrates blanks in which an excess portion 32 is formed to the edge of the portion that will
form the flange section 20d. Fig. IOB illustrates the blank 37 (Comparative Example 2),
formed with a recess portion 46 with a curvature on the edge of the excess portion 32 having a
negative sign (radius of curvature 300 mm). Fig. IOC illustrates the blank 38 (Comparative
Example 3), in which the excess portion 32 is formed with a straight-line edge 47. Fig. 10D
illustrates the blank 39 (Cotnparative Example 4) formed with a recess 48 and a protrusion 49,
each having a radius of curvature of 150 tntn, next to each other along the edge of the excess
portion 32. Fig. 10E illustrates the blank 30 (the present Example) formed with the first
recess 33, the protrusion 34, and the second recess 35, each having a radius of curvature of
100 mtn, next to each other along the edge of the excess portion 32.
[0140] Table 1 illustrates the results of investigating the plate thickness reduction ratio and
cracking in the portionA and in the portion B respectively in the press formed article 20
illustrated in Fig. 1. Note that the 1ocationAl to the location A3 in Table 1 refer to the
locations in Fig. 1.
[0141] Table 1
I I I I
Cracking at die I
Blank Shape
Cracking at edge
location A1
IroundedlocationI present I present I absent I absent I absent
Comparative
Example 3
(38)
A2
Cracking at
Colnparative
Example 1
(36)
present
I verticalwall I absent I absent I present I present I absent
Comparative
Example 4
(39)
Conlparative
Example 2
(37)
location A3
Example
(30)
absent
I plate edge I absent I absent I present / present I absent
location B
absent
[0142] As illustrated in Table 1, flange cracking occurred at the portion A it1 the
Comparative Example 1. -.It cambe seen that althougl~th e plate thickness reduction ratio at
the portion A decreases as the surface area provided for the excess portion 32 becomes larger,
as it1 the Comparative Exatnples 2 to 4, and the risk of flange cracking at the poition A is
lower, the plate thickness reduction ratio becomes larger at the portion B, and so the risk of
top plate edge cracking at the portion B is higher.
[0143] On the other hand, in the Example of the present invention, not only can the smallest
plate thickness reduction ratio at the portion A be achieved, but also the plate thickness
reduction ratio at the portion B can also be kept smaller than in the blanks 38, 39 of the
absent
Comparative Examples 3 and 4. This thereby enables the occurrence of top plate edge
cracking to be prevented at the portion B as well as preventing flange section edge cracking at
poltion A.
[0144] The blank 30 is formed into an intermediate pressed body by the fiee bending
absent
method in this manner. After performing further bending as required to the intermediate
pressed body formed in this manner, trinnning is performed to give the external profile the
desired shape, and holes are formed to manufacture the pressed body product.
[0145] Example
Fig. 11 is a perspective view illustrati~igth e shape ofa press formed article 50, this
being a configuration component of a vehicle fsamework colnponent produced as a sample
28
using the present Example.
[O 1461 As illustrated in Fig. 11, the press formed article 50 has an overall length of 1000 mnl,
and a top plate section 50a has a width of 100 nnn at both the X1 direction and tlie X2
direction end portions, a height of a vertical wall section 50c of 70 mtn, and a width of a
flange section 50d of 25 mm.
[0147] Blanks for the press formed article 50 are formed from thee types of high tensile
steel plates, having respective tensile strengths of 590 MPa grade, 980 MPa grade, and 1180
MPa grade, and each having a plate thickness of 1.6 mm. In the opened-out shape of the
press formed article, the excess portion 32 illustrated in Fig. 3 is formed to the edge of a
portion that will form a curving portion of a flange, and the first recess 33, the protrusion 34,
and the second recess 35 are provided to the edge of the excess portion 32.
[0148] The press formed article 50 illustrated in Fig. 11 is tnanufactured by etnploying the
three types of blank with different strength levels, using the free bending method in which
each blank is placed on a punch, and the portion that will form the top plate section is held
down by a pad, before then bending using a die.
[0149] The results demonstrate that good pressing of the press formed article 50 according
to the present invention illustrated in Fig. 11 could be achieved whichever of the 3 types of
blank is employed, withogt flange cracking occnrring at locationA1, without cracking
occurring at the die rounded locationA2, without cracking occurring at the vertical wall
IocationA3, and, moreover, without cracking occurring at the top plate edge location B.
[0150] The entire contents of tl~ed isclosure of Japanese Patent Application No.
2013-101419, filed May 13,2013, are incorporated by reference in the present specification.
I~idzts/riaAl pplicability
[0151] As described above, the present invention enables high quality and efficient forming
with high strength steel plates and the like. The present invention has a high degree of
applicability in steel plate processing technology industries, for example in the automotive industry.

CLAIMS
1. A flat plate shaped blank for pressing to manufacture a \vorked comnponent, the worked
component comprising:
a top plate section comprising, of a pair of outer edge portions, at least one outer
edge portion that has, in plan view, a straight-line outer edge portion of a straight line and a
curved-line outer edge portion that is contiguous to the straight-line outer edge portion and
that curves in a concave shape so as to move away fiom the other outer edge portion toward
an outer side;
a vertical wall section coniprising a flat vertical wall portion that is bent downward
from the outer edge portion and that is formed following the straight-line outer edge portion,
and a curved vertical wall portion that is formed following the curved-line outer edge portion;
and
a flange section comprising a straight-line flange portion that extends from the flat
vertical wall portion toward the outer side and that is formed following the straight-line outer
edge portion, and a curved-line flange portion that is formed following the curved-line outer
edge portion and that extends from the curved vertical wall portion toward the outer side,
wherein:
an excess portion is provided at a location corresponding to an edge of the flange
section in an opened-out shape of the worked coniponent, the excess portion being formed
with a protmsion forming a protruding shape toward the outer side, and a first recess and a
second recess respectively forming recessed shapes on either side of the protrusion; and
at least the protmsion is provided at a location corresponding to an edge of the
curved-line flange portion.
2. The blank of claim 1, wherein the excess portion further comprises a straight-line portion
forming a straight line in plan view at at least one of between the first recess and the
protrusion, or between the protrusion and the second recess.
3. Aforming plate comprising the blank of claitn 1 or claim 2, on which pre-processing has
been performed prior to pressing.
4. Arnethod of matmfacturing method a press formed article, the method comprising:
placing the blank of claim 1 or claim 2, or the forming plate of claim 3, between a die,
and a pad and a bending mold; and
30
in a state in which a poi-tion of the blank, or of the forming plate, that will form an
end portion of the top plate section, the vertical wall section, and the flange section is present
in the same plane as a poi-tion of the blank, or of the forming plate, that will form the top plate
section, press forming the vertical wall section and the flange section by bending while
moving the end portion in-plane with respect to a location of the die corresponding to the top
plate section, by relatively moving either the die or the bending mold in a direction so as to
approach each othel; in a state in which an out-of-plane deformation suppression region that is
part of a portion of the blank, or of the forming plate, that will fonn the top plate section, is
being applied with pressure by the pad.
5. A method of tnannfacturing a press formed article, the method comprising:
placing the blank of claim 1 or claiin 2, or the forming plate of claim 3, between a die,
and a pad, and a bending mold; and
in a state in which a portion of the blank, or of the forming plate, that will form an
end portion of the top plate section, the vertical wall section, and the flange section, is present
in the same plane as a portion of the blank, or of the forming plate, that will form the top plate
section, pressing forming the vertical wall section and the flange section by bending, by
placing the pad in the vicinity of, or in contact with, an out-of-plane deformation suppression
region that is part of a portion of the blank, or of the forming plate, that will form the top plate
section, and relatively moving either the die, or the bending mold, in a direction so as to
approach each other while maintaining a gap between the pad and the die of froin the plate
thickness to 1 .I times the plate thickness of the blank, or of the forming plate.
6. The method of manufacturing a p ~ sfsor n~eda rticle of either claim 4 or claim 5, wherein,
in plan view of the blank or the forming plate, the out-of-plane deforination suppression
region is a region that is on a side of a location that will form the curved-line outer edge
poi-tion out of regions of the portion that will form the top plate section that are divided into
two by an extension line of a line that will form the straigl~t-lineo uter edge portion, and that
is a region that contacts the die.
7. The method of manufacturing a press formed article of any one of claim 4 to claim 6,
wherein a portion that is an end portion of the blank, or of the forming plate, and that is
present further toward a side that will fonn the top plate section than the curved-line outer
edge portion out of locations corresponding to the out-of-plane deformation suppression
region of the blank, or of the forming plate, is present in the same plane as a portion that will
3 1
form tlie top plate section.
8. The method of manufacturing a press formed ai-ticle of any one of claim 4 to claitn 7,
wherein the height of the vertical wall section is either 0.2 times tlie length of the curved-line
outer edge poi-tion or greatel; or 20 mnl or greater.
9. The method of manufacturing a press formed article of any one of claim 4 to claim 8,
wherein the vertical wall section and tlie flange section are formed by placing the pad in the
vicinity of, or in contact with, a region that is inside a portion of the blank, or of the forming
plate, that will form the top plate section, and that is a region that extends up to at least 5 mnl
from the curved-line outer edge portion toward the side that will form the top plate section.
10. The method of manufacturing a press formed article of any one of claim 4 to claim 9,
wherein the width of the flange section, from a central position of the curved-line outer edge
portion to a position separated by 50 mm or greater from an end portion of the curved-line
outer edge portion toward the straight-line outer edge portion side, is from 25 mm to 100 mm.
I I. The method of manufact~i,nga press formed article of any one of claim 4 to claitn 10,
wherein the maximum radius of curvature of the curved-line outer edge portion of the top
plate section is from 5 mm to 300 mm.
12. The method of manufacturing a press formed article of any one of claitn 4 to claim 11,
wherein the tensile strength of the blank, or of the forming plate, is from 400 MPa to 1600
MPa.
13. A press formed article comprising:
a top plate section comprising, out of a pair of outer edge portions, at least one outer
edge portion that has, in plan view, a straight-line outer edge portion of a straight line and a
curved-line outer edge poltion that is contiguous to the straight-line outer edge portion and
that curves in a concave shape so as to move away from the other outer edge portion toward
an outer side;
a vertical wall section colnprising a flat vertical wall portion that is bent downward
from the outer edge portion and that is formed following the straight-line outer edge poi-tion,
and a curved vertical wall portion that is formed following the curved-line outer edge portion;
and
32
a flange section comprising a straight-line flange pol.tion that extends fiom the flat
vertical ulall portion toward the outer side, and that is for~nedfo llowing the straight-line outer
edge portion, and a curved-line flange portion that is fornled following the curved-line outer
edge portioi~a nd that extends from the curved vertical wall portion toward the outer side,
wherein:
the width of an end portion of the top plate section on fhe curved-line portion side is
150 nun or greater; and
the press fortned article is obtained by press foming, with cold bending, a material
that is a blatlk having a tensile strength of fiom 400 MPa to 1600 MPa, or a forming piate of
the blank on url~chp re-processing has beeti perfonned.