The present invention relates to a press-forming apparatus and a press-forming
method for a high strength and/or long size press-formed article, which is used for a
structure member of a vehicle body such as a side sill or a floor cross member.
Priority is claimed on Japanese Patent Application No. 2015-096908, filed on
May 11, 2015, the content of which is incorporated herein by reference.
[Related Art]
[0002]
As is widely known, automotive bodies have a so-called monocoque structure
configured by a body shell having a box type structure as a basic structure in which a
plurality offormed panels are overlapped and joined at each of edge portions; and a
reinforcement framework member joined to the box type structure at a specific portion
such as a portion applied with a stress and a portion loaded by a heavy object. As an
example of such framework members, there is a side sill which is joined to both edge
portions in the automotive width direction of a floor panel. The side sill is a close
sectional member assembled by overlapping and welding a side sill outer panel, a side sill
inner reinforcement arranged if required, and a side sill inner panel, which are
press-formed article, at flange portions formed at end portions ofthese members.
[0003]
FIG. SA is a perspective view showing an example shape of a side sill inner panel
0 constituting the side sill, and FIG. 88 is a plan view showing an example shape of the
side sill inner panel 0.
2
As shown in FIG. 8A and FIG. 8B, the side sill inner panel 0 is generally
manufactured by press-forming a material (blank) of a steel sheet by using a punch and a
die, so as to obtain a press-formed article with a hat type cross-section configured by the
following portions (a) to (e).
(a) top portion 0-1
(b) two ridge portions 0-2a, 0-2b, which are formed on both edges of the top portion 0-1
(c) two sidewall portions 0-3a, 0-3b, which connect to each ofthe two ridge portions 0-2a,
0-2b
(d) two bending portions 0-4a, 0-4b, which connect to each of the two sidewall portions
0-3a, 0-3b
(e) two flange portions 0-Sa, 0-Sb, which connect to each of the two bending portions 0-4a,
0-4b
[0004]
It should be noted that a recessed portion 0-6 is formed on the top portion 0-1 of
the side sill inner panel 0 shown in FIG. 8A and FIG. SB. However, the top portion 0-1
may be formed with a shape other than the recessed portion 0-6, and the top portion 0-1
may have a planar shape without such a specific shape.
In addition, the term "press-formed article with a substantially U shaped
cross-section" used in this specification means a part including at least the above portions
(a), (b), and (c). Further, the term "press-formed article with a hat type cross-section" is
a part in which a bending portion and a flange portion are added to the "press-formed
article with a substantially U shaped cross-section".
[0005]
For the side sill, there is a tendency of higher strength and thinner thickness as an
approach of a vehicle weight saving for achieving further reduction of C02 emission and
3
improving collision safety properties. Therefore, for example, a side sill having a high
strength of not less than 980 MPa has been used, and recently, even a side sill having a
ultra-high strength of not less than 1180 MPa with a thickness of 1.2 mm has been
demanded. On the other hand, to cope with an enlargement of vehicle bodies and an
integration of parts, demands for higher strength and/or longer size ofthe side sill are
increased. Therefore, as exemplified in FIG. 8B, it is considered to use, as a blank, a
galvannealed steel sheet (GA steel sheet) having a thickness of 1.2 mm, a tensile strength
of not less than 1180 MPa, and a total length of about 2200 mm.
[0006]
For the mass-production of such high strength and/or long size side sill inner panel or a
side sill outer panel on an industrial scale, following means (i) and (ii) may be considered.
(i) performing a roll forming by a sequential bending processing by using a plurality of
forming rolls linearly arranged through which a strip material is continuously passed, and
final rolls for obtaining a product with a desired cross-section.
(ii) performing a press-forming using a transfer press-machine having a fingering
mechanism that grips a strip used as a blank in a multi-stage forming tool placed on a
press bolster, and a transfer mechanism that conveys the gripped strip.
[0007]
However, in a case of using the above (i), the productivity by the roll forming is
low as compared to a press forming, and further, it is impossible to manufacture a formed
product in which a cross sectional shape varies along the longitudinal direction.
Accordingly, by the roll forming method, it is not easy to realize a mass production of the
side sill inner panel or the side sill outer panel with high strength and/ or long size.
[0008]
4
On the other hand, in a case of the above (ii), for the mass-production of the side
sill inner panel or the side sill outer panel with high strength and/or long size, it is
necessary to perform press-forming by using, for example, 2500 tons class transfer press
machine. Accordingly, if the blank having a tensile strength of 1180 MPa and a
thickness of 1.2 mm is used, the maximum length of the blank is limited to about 1700
mm, and thus, there is a problem in a forming load and a producible length.
[0009]
Further, when a ultra-high strength blank having a tensile strength of not less than
980 MPa is press-formed by using a punch and a die, a portion in the blank formed to be a
sidewall portion is subject to a bending/unbending deformation by the punch and the die
in a process of press-forming, therefore, a bending moment is generated at the
press-formed sidewall portion. Then, when a formed product is removed from a forming
tool and the pressure applied by the punch and the die is released, a spring back tends to
occur which is a phenomenon that two sidewall portions becomes an opened shape from a
shape (product shape) when a load has been applied, due to an elastic deformation
recovery.
[0010]
FIG. 9A to FIG. 9D are explanation diagrams showing an invention of Patent
Document 1 in a time line.
[00 II]
Though Patent Document 1 is not directly directed to a manufacturing of a side
sill inner panel or a side sill outer panel, Patent Document 1 discloses an invention for
manufacturing a high strength press-fmmed article with hat type cross-section while
suppressing a spring back of sidewall portions, by using a bending processing tool 1000
equipped with a punch 1002, a die I 003, a flange bending tool1008, and a blank holder
5
1006. More specifically, the press-formed article is manufactured by:
(1) a first step of placing a blank 1001 on the bending tooll008, as shown in FIG. 9A,
(2) a second step of forming a flange portion by using a flange bending tool so as to bend
end portions of the blank 1001 in the width direction in a state where portions in the blank
I 001 to be formed into the sidewall portions are clamped by the die I 003 and the blank
holder 1006, as shown in FIG. 9B,
(3) a third step of moving away the blank holder 1006 from a position adjacent to the
portion in the blank 1001 to be formed into the sidewall portion toward a lower direction
by a cylinder 1009, as shown in FIG. 9C, and
( 4) a fourth step of forming the sidewall portion by performing a bending processing using
the die 1003 and the punch 1002, as shown in FIG. 9D.
It should be noted that, in FIG. 9A to FIG. 9D, a reference number I 004 indicates
a shoulder portion of the punch 1002, a reference number 1005 indicates a shoulder
portion of the die 1003, a reference number 1007 indicates a hat-head portion pad
member, and a reference number 1010 indicates a pipework for driving the cylinder I 009.
[Prior Art Document]
[Patent Document]
[0012]
[Patent Document 1] Japanese Unexamined Patent Application, First
Publication No. 2004-167593
[Disclosure of the Invention]
[Problems to be Solved by the Invention]
[0013]
The invention disclosed in Patent Document 1 forms the sidewall portions by
lowering a pair of the dies 1003 simultaneously, and thus, a forming load becomes
6
excessrve. Accordingly, for example, in order to press-form a blank with a tensile
strength of not less than 980 MPa and a length oflonger than 1700 mm, it is impossible to
realize an accurate press-forming by using a conventional 1200 tons class press-forming
facility. Therefore, it is necessary to employ a new press-forming apparatus that can
exhibit high pressing load, such as 2500 tons class. Therefore, the cost for the facility
mcreases.
[0014]
Further, the invention disclosed in Patent Document 1 rises and lowers the blank
holder 1006 by using the cylinder 1009 arranged under the flange bending tool 8.
Accordingly, the height of the press-forming apparatus increases in order to secure a
stroke range for raising and lowering the blank holder 6.
[0015]
The present invention has been made in view of the above problems of these
related art, and an objective of the present invention is to provide a press-forming
apparatus and a press-forming method that can manufacture a high strength and/or long
size press-formed article while suppressing the excessive amount of the maximum
press-forming load and the excessive size of the press-forming apparatus in the
press-forming direction.
[Means for Solving theT'roblem]
[0016]
The present invention employs the following means.
(1) A first aspect ofthe present invention is a press-forming apparatus for manufacturing
a press-formed article from a workpiece sheet by moving at least one of a die and a punch
so as to be close to each other in a press-forming direction, the press-formed article having
a top portion, a first sidewall portion, and a second sidewall portion, the first sidewall
7
portion and the second sidewall portion being connected to ridge portions formed on both
edges of the top portion, wherein the die includes: a die slide; a first divisional die
arranged at the die slide so as to be adjacent to a first side face of the punch in a state
where the die and the punch are the closest to each other; a second divisional die arranged
at the die slide so as to be adjacent to a second side face of the punch in a state where the
die and the punch are the closest to each other, the second side face being an opposite side
face of the first side face; a second divisional die driving unit configured to move the
second divisional die in the press-forming direction so as to separate the second divisional
die from the die slide; a die pad arranged between the first divisional die and the second
divisional die; a die pad driving unit configured to move the die pad in the press-forming
direction; an insert block having a base end portion configured to be inserted between the
die slide and the second divisional die in a state where the die slide and the second
divisional die are separated from each other; and an insert block driving unit configured to
move the insert block in a direction perpendicular to the press-forming direction.
(2) In the press-forming apparatus in the above (I), the insert block may have a tip end
portion which extends from the base end portion to the direction perpendicular to the
press-forming direction, and which is configured to be inserted between the die slide and
the die pad in a state where the die slide and the die pad are separated from each other, and
the thickness ofthe base end portion may be thicker than the thickness of the tip end
portion.
[0017]
(3) In the press-forming apparatus in the above (I) or (2), the press-formed article may
have a flange portion which connects a bending portion formed on an edge of at least one
ofthe first sidewall portion and the second sidewall portion.
(4) The press-fanning apparatus in the above (3) may include a flange forming tool
8
arranged between the die and the punch; and a flange forming tool driving unit configured
to move the flange forming tool between a position where a stroke range of the first
divisional die or the second divisional die is interfered, and a position where a stroke
range ofthe first divisional die or the second divisional die is not interfered, wherein an
upper face of the flange forming tool and a lower face of at least one of the first divisional
die and the second divisional die may have a shape corresponding to a face shape of the
bending portion and the flange portion.
(5) In the press-forming apparatus in the above (4), the flange forming tool driving unit
may be configured to move the flange fanning tool into the direction perpendicular to the
press-forming direction.
( 6) In the press-forming apparatus in the above ( 4) or ( 5), a lower face of the flange
forming tool may be in surface-contact with a ground face of the punch.
[0018]
(7) The press-forming apparatus in any one ofthe above (1) to (6) may include a punch
pad configured to be housed in a recessed portion formed in a top face of the punch, and a
punch pad driving unit configured to move the punch pad in the press-forming direction.
(8) In the press-forming apparatus in any one of the above (1) to (7), the first divisional
die may be formed integrally with the die slide.
(9) In the press-forming apparatus in any one of the above (1) to (8), the die slide may
be connected to a single driving shaft.
[0019]
(I 0) In the press-forming apparatus in any one ofthe above (1) to (9), the workpiece
sheet may be a steel sheet.
(11) In the press-forming apparatus in any one of the above (1) to (10), a tensile strength
ofthe workpiece sheet may be not less than 980 MPa.
9
(12) In the press-forming apparatus in any one of the above (1) to (11), the total length
of the workpiece sheet may be more than 1700 mm.
[0020]
(13) A second aspect ofthe present invention is a press-forming method for
manufacturing the press-formed article by using the press-forming apparatus according to
any one of the above (1) to (12), the press-forming method including; forming the first
sidewall portion by moving the die slide toward the punch in a state where the insert block
is not inserted between the die slide and the second divisional die; and forming the second
sidewall portion by moving the die slide toward the punch in a state where the insert block
is inserted between the die slide and the second divisional die.
[0021]
(14) In the press-forming method according to the above (13), after performing the
forming of the first sidewall portion, the insert block may be inserted between the die slide
and the second divisional die, and the forming of the second sidewall portion may be
perfom1ed.
(15) In the press-forming method according to the above (14), in the forming of the first
sidewall portion, a portion in the workpiece sheet corresponding to the second sidewall
portion may be pre-formed by using the second divisional die.
(16) In the presscforming method according to the above (13), after performing the
forming ofthe second sidewall portion, the insert block may be pulled out from between
the die slide and the second divisional die, and the forming of the first sidewall portion
may be perfonned.
(17) In the press-fanning method according to the above (16), in the fanning of the
second sidewall portion, a portion in the workpiece sheet corresponding to the first
sidewall portion may be pre-formed by using the first divisional die.
10
[0022]
(18) In the press-forming method according to any one ofthe above (13) to (!7), before
performing the forming of the first sidewall portion and the forming of the second
sidewall portion, the die slide may he relatively moved toward the punch in a state where a
flange forming tool is arranged at a position interfering with a stroke range of the first
divisional die and the second divisional die, thereby forming a flange portion in the
workpiece sheet by using the flange forming tool and at least one ofthe first divisional die
and the second divisional die.
[0023]
(19) In the press-forming method according to any one ofthe above (13) to (18), in at
least one of the forming ofthe first sidewall portion and the forming ofthe second
sidewall portion, the die slide may be lowered in a state where a punch pad configured to
be housed in a recess portion formed in a top face of the punch is positioned high above a
top face of the punch, and the punch pad may be lowered in accordance with the lowering
of the die slide to complete a press-forming.
[Effects of the Invention]
[0024]
According to the above aspects of the present invention, it is possible to
manufacture a high strength and/or long size press-formed article while suppressing the
excessive amount of the maximum press-forming load and the excessive size of the
press-forming apparatus in the press-forming direction.
[Brief Description of the Drawings]
[0025]
FIG. I is a cross sectional view of a press-formed article having a substantially U
shaped cross-section.
11
FIG. 2A is a view showing a press-forming method using a press-forming
apparatus according to a first embodiment of the present invention, indicating a state
before starting a press-forming.
FIG. 2B is a view showing a press-forming method using a press-forming
apparatus according to a first embodiment of the present invention, indicating a state
where a first divisional die forms a first sidewall portion and a second divisional die
pre-forms a second sidewall portion.
FIG. 2C is a view showing a press-forming method using a press-forming
apparatus according to a first embodiment of the present invention, indicating a state
where an insert block is inserted between a die slide and both of a second divisional die
and a die pad.
FIG. 20 is a view showing a press-forming method using a press-forming
apparatus according to a first embodiment of the present invention, indicating a state
where a second divisional die forms a second sidewall portion.
FIG. 3 is a cross sectional view of a press-fanned article having a hat type
cross-section.
FIG. 4A is a view showing a press-forming method using a press-forming
apparatus according to a second embodiment ofthe present invention, indicating a state
before starting a presscforming.
FIG. 4B is a view showing a press-forming method using a press-forming
apparatus according to a second embodiment ofthe present invention, indicating a state
where a flange forming tool, a first divisional die, and a second divisional die form a
flange portion.
12
FIG. 4C is a view showing a press-forming method using a press-forming
apparatus according to a second embodiment of the present invention, indicating a state
where a flange forming tool is moved away in the horizontal direction.
FIG. 4D is a view showing a press-forming method using a press-forming
apparatus according to a second embodiment of the present invention, indicating a state
where a first divisional die forms a first sidewall portion and a second divisional die
pre-forms a second sidewall portion.
FIG. 4E is a view showing a press-forming method using a press-forming
apparatus according to a second embodiment of the present invention, indicating a state
where an insert block is inserted between a die slide and both of a second divisional die
and a die pad.
FIG. 4F is a view showing a press-forming method using a press-forming
apparatus according to a second embodiment of the present invention, indicating a state
where a second divisional die forms a second sidewall portion.
FIG. SA is a view showing a press-forming method using a press-forming
apparatus according to a third embodiment of the present invention, indicating a state
before starting a press-forming.
FIG. 58 is a view showing a press-forming method using a press-forming
apparatus according to a third embodiment of the present invention, indicating a state
where a flange forming tool, a first divisional die, and a second divisional die form a
flange portion.
FIG. 5C is a view showing a press-forming method using a press-forming
apparatus according to a third embodiment of the present invention, indicating a state
where a flange forming tool is moved away in the horizontal direction.
13
FIG. 50 is a view showing a press-forming method using a press-forming
apparatus according to a third embodiment of the present invention, indicating a state
where a first divisional die forms a first sidewall portion and a second divisional die
pre-forms a second sidewall portion.
FIG. 5E is a view showing a press-forming method using a press-forming
apparatus according to a third embodiment of the present invention, indicating a state
where an insert block is inserted between a die slide and both of a second divisional die
and a die pad.
FIG. 5F is a view showing a press-forming method using a press-forming
apparatus according to a third embodiment of the present invention, indicating a state
where a second divisional die forms a second sidewall portion.
FIG. 6 is a graph showing an example of a relationship between a press-forming
stroke and a press-forming load in a case where a press-formed article having a hat type
cross-section is manufactured by using a press-forming apparatus according to a third
embodiment of the present invention.
FIG. 7 is a graph showing an example of a relationship between a stroke of a
punch pad and a spring back amount.
FIG. 8A is a perspective view of a side sill inner panel.
FIG. 8B is a: plan view of a side sill inner panel.
FIG. 9A shows a first step of a press-forming method disclosed in the Patent
Document 1.
FIG. 9B shows a second step of a press-forming method disclosed in the Patent
Document 1.
FIG. 9C shows a third step of a press-forming method disclosed in the Patent
Document 1.
14
FIG. 9D shows a fourth step of a press-forming method disclosed in the Patent
Document I.
[Embodiments ofthe Invention]
[0026]
The inventors obtained following new and important fmdings (A) to (C), as a
result of earnest investigations to achieve the above objective.
[0027]
(A) It is possible to significantly reduce a maximum press-forming load by performing
press-forming of one sidewall portion and thereafter performing press-forming of the other
sidewall portion, unlike the invention disclosed in Patent Document 1 which performs
press-forming of left and right sidewall portions at the same time. This makes it possible
to employ a conventional 1200 tons class press-forming apparatus for press-forming a
blank having a tensile strength of not less than 1180 MPa and a length of more than 1700
mm. In addition, by press-forming one sidewall portion and pre-forming the other
sidewall portion simultaneously, and thereafter press-forming the other sidewall which is
pre-formed, it is possible to reduce the maximum press-forming load and suppress the
generation of spring back so as to improve the dimensional accuracy.
[0028]
(B) It is possibleto prevent the height of the press-forming apparatus from increasing,
by moving a blank holder toward a horizontal direction after forming the flange, unlike the
invention disclosed in Patent Document 1 which moves the blank holder toward the lower
direction after forming the flange.
[0029]
(C) Jt is possible to practically overcome the generation of spring back in the
press-fonned article, by providing a punch pad which is movable to be in-out, positioning
15
the blank above the upper face of the punch by the punch pad when the press-forming of
the one sidewall portion is started and when the press-forming of the other sidewall
portion is started, lowering the punch pad in accordance with the proceeding of the press
fording of the one sidewall portion and the other sidewall portion, and housing the punch
pad in the punch at the press-forming bottom dead point.
[0030]
The present invention on the basis of the above findings (A) to (C) will be
explained with reference to the attached drawings.
[0031]
(First Embodiment)
Hereinafter, a press-forming apparatus l according to a first embodiment of the
present invention will be explained in detail with reference to FIG. 1 and FIG. 2A to FIG.
20.
[0032]
FIG. 1 is a cross sectional view of a press-formed article I 00 having a
substantially U shaped cross-section. This cross sectional view is taken along a plane
which is perpendicular to the longitudinal direction of the press-fonned article. As
shown in FIG. 2A to FIG. 20, the press-forming apparatus l according to this
embodiment relatively moves a die 10 and a punch 20 in the press-forming direction,
thereby manufacturing the press-formed article I 00 from a steel sheetS.
[0033]
(Steel sheet S)
The steel sheet S which is a workpiece sheet may be a sheet, for example having
a tensile strength of not less than 980 MPa, a length in the longitudinal direction of more
than 1700 mm, and a thickness of 0.8 to 2.3 mm. In this embodiment, as the steel sheetS,
16
a flat sheet with no particular shape, but a sheet may be pre-formed with a particular
shape.
[0034]
(Press-formed article I 00)
The press-fom1ed article 100 includes a substantially U shaped cross-section as
shown in FIG. 1, and has a top portion 101, a first sidewall portion 103 and a second
sidewall portion 105 which connect to ridge portions 1 02a, I 02b which are formed at both
ends of the top portion 101. As shown in FIG. 1, the top portion 101, the first sidewall
portion I 03, and the second sidewall portion 105 may be fonned with a particular surface
shape.
[0035]
(Punch20)
The punch 20 is provided to face the die 10 in the press-forming direction, and
has a first side face 20a which is fonned with a shape corresponding to the first sidewall
portion 103, a second side face 20b which is a face opposite to the first side face 20a and
which is formed with a shape corresponding to the second sidewall portion 105, and a top
face 20c which faces the die 10.
[0036]
(Die)
The die I 0 includes a die slide !I, a first divisional die 13, a second divisional die
15, a second divisional die driving unit 150, a die pad 17, a die pad driving unit 170, an
insert block 19, and an insert block driving unit 190. Hereinafter each of the
components will be explained.
[0037]
(Die slide 11)
17
As shown in FIG. 21\ the die slide 11 has a below surface at which a first
divisional die 13 and a second divisional die 15 are provided, and the die slide 11 is
connected to a single driving shaft or a plurality of driving shafts, which are not shown, so
as to be movable in the vertical direction. The die slide 11 may be formed with a
recessed portion for housing a second divisional die driving unit 15D for adjusting a
separation distance from the second divisional die 15 in the vertical direction. The die
slide ll is formed with a suspending portion llA to which an end portion of the insert
block driving unit 19D, which will be explained later, is fixed.
[0038]
(First divisional die l3)
The first divisional die l3 is provided to the die slide 11 so as to be adjacent to a
first side face 20a of the punch 20 in a state where the die 1 0 and the punch 20 are closest
to each other. In the example shown in FIG. 2A to FIG. 2D, the first divisional die l3
and the die slide II are drawn as separate members, but the first divisional die 13 and the
die slide 11 may be formed integrally.
[0039]
(Second divisional die 15)
The second divisional die 15 is provided to the die slide 11 so as to be adjacent to
a second side face 20b ofthe punch 20 in a state where the die 10 and the punch 20 are
closest to each other.
[0040]
(Second divisional die driving unit 15 D)
The second divisional die driving unit 15D is provided between the die slide 11
and the second divisional die 15, and is connected to a control unit not shown so as to
drive the second divisional die 15, for approaching or separating the second divisional die
18
15 with respect to the die slide 15. More specifically, the second die driving unit 15D
may be a pressing mechanism or an electrical motor that generates a gas pressure, an oil
pressure, an air pressure, spring pressure, or the like.
[0041]
(Die pad 17)
The die pad 17 is provided between the tlrst divisional die 13 and the second
divisional die 15, and has a lower face having a shape corresponding to the top portion
101 and an upper face to which a lower end portion of a shaft 1 7 a extending in the vertical
direction is connected. The steel sheetS is press-formed in a state of being pressed by
the die pad 17. It should be noted that in the example of this embodiment, the shaft 17a
is formed so as to penetrate the die slide 11, and the upper end portion ofthe shaft 17a is
connected to the die pad driving unit 17D.
[0042]
(Die pad driving unit 17D)
The die pad driving unit 17D is provided in or on the die slide 11, and is
connected to a control unit not shown, so as to drive the die pad 17 in the press-forming
direction such that the steel sheet S is clamped by the punch 20 and the die pad 17 at least
during press-forming.
More specifically, the die pad driving unit 17D may be a pressing mechanism or
an electrical motor that generates a gas pressure, an oil pressure, an air pressure, spring
pressure, or the like.
[0043]
(Insert block 19)
The insert block 19 has a base end portion 19a and a tip end portion 19b. The
base end portion 19a is configured to be inserted between the die slide 11 and the second
19
divisional die 15, in a state where the die slide 11 and the second divisional die 15 are
separated from each other. The tip end portion 19b extends from the base end portion
19a to a direction perpendicular to the press-forming direction (right direction in the
drawing), and is configured to be inserted between the die slide 11 and the die pad 1 7 in a
state where the die slide II and the die pad 17 are separated from each other. The height
(thickness) of the base end portion 19a is larger than the height (thickness) ofthe tip end
portion 19b.
Accordingly, as shown in FIG. 2D, in a state where the insert block 19 is inserted,
the base end portion 19a can adjust the gap in the height between the die slide 11 and the
second divisional die 15 by the height (thiclmess) of the base end portion 19a. In
addition, the tip end portion 19b can adjust the gap in the height between the die slide ll
and the die pad 17 by the height (thickness) of the tip end portion l9b.
Accordingly, it is possible to perform a press-forming by means of the first
divisional die 13 and a press-forming by means of the second divisional die 15 at different
timing. Further, it is possible to clamp the top portion by the punch 20 and the die pad
17 in both of the press-forming by means of the first divisional die l3 and the
press-fonning by means of the second divisional die 15.
[0044]
(Insert block driving unit 19D)
The insert block driving unit l9D has one end which is fixed to the suspending
portion llA of the die slidell, and the other end which is fixed to the side face of the
base end portion 19a of the insert block 19. The insert block driving unit 19D is
connected to a controlling unit not shown, and moves the insert block 19 in the horizontal
direction so as to insert the insert block 19 between the die slide 11 and the second
divisional die 15 and between the die slide 11 and the die pad 17, or pull out the insert
20
block 19 therefrom in the horizontal direction. More specifically, the insert block driving
unit 19D may be a pressing mechanism or an electrical motor that generates a gas pressure,
an oil pressure, an air pressure, spring pressure, or the like.
[0045]
(Press-forming method)
An example ofthe press-forming method using the press-forming apparatus 1
according to this embodiment will be explained with reference to FIG. 2A to FIG. 2D.
[0046]
First, as shown in FIG. 2A, the steel sheet S is placed on the punch 20.
[0047]
Next, as shown in FIG. 28, the die slide II is lowered so as to form the first
sidewall portion I 03 by the first divisional die l3 and the first side face 20a of the punch
20. At this timing, the second divisional die 15 and the punch 20 are separated from each
other in the vertical direction, and therefore, the second sidewall portion I 05 is not formed.
However, it is preferable that the second sidewall portion 105 be pre-formed by the
lowering of the second divisional die 15. In this case, the spring back of the second
sidewall portion l 05 can be suppressed, thus, the dimensional accuracy ofthe
press-formed article 100 can be increased.
[0048]
Next, as shown in FIG. 2C, the die slide II is rose and a gap is formed between
the die slide 11 and both of the second divisional die 15 and the die pad 17. Then, the
insert block 19 is inserted into this gap, thereby positioning the base end portion 19a ofthe
insert block 19 between the die slide 11 and the second divisional die 15, and positioning
the tip end portion 19b of the insert block 19 between the die slide 11 and the die pad 17.
[0049]
21
Next, as shown in FIG. 2D, the press-formed article 100 is obtained by lowering
the die slide 11 to form the second sidewall portion 105 in a state where the insert block
19 is inserted.
[0050]
It should be noted that, in the above example, the first sidewall portion 103 is
firstly formed and thereafter the second sidewall portion 105 is formed, however, it may
be possible that the second sidewall portion 105 is firstly formed and thereafter the first
sidewall portion 103 is formed. In this case, the second sidewall portion I 05 is formed
and if necessary, the first sidewall portion 103 is pre-formed in a state where the insert
block 19 is inserted, and thereafter, the first sidewall portion 103 is formed in a state
where the insert block 19 is pulled out in the horizontal direction.
[0051]
By means of the press-forming apparatus 1 according to the this embodiment,
because the insert block 19 movable in the horizontal direction is used, it is possible to
press-form the first sidewall portion 103 and the second sidewall portion 105 at a different
timing, without increasing the size in the height direction of the press-forming apparatus 1.
In addition, the top portion 10 I can be clamped by the die pad 17 and the punch 20 at a
time of press-forming the first sidewall portion 103 and at a time of press-forming the
second sidewall portion lOS, therefore, the dimensional accuracy of the press-formed
article 100 can be improved. Accordingly, for example, by using a conventional 1200
tons class press-forming apparatus, it is possible to obtain a press-formed article 100
having a substantially U shaped cross-section with high dimensional accuracy from a
blank with a tensile strength of not less than 980 MPa and a length of longer than 1700
mm.
[0052]
22
(Second Embodiment)
Hereinafter, a press-forming apparatus 1' according to a second embodiment of
the present invention will be explained with reference to FIG. 3 and FIG. 4A to FIG. 4F.
To simplifY the explanation, members used in the press-forming apparatus 1 according to
the first embodiment are applied with the same reference numeral, and the same
explanation is omitted.
[0053]
FIG. 3 shows a cross sectional view of a press-formed article 100' having a hat
type cross-section obtained by this embodiment, which is taken along a plane
perpendicular to the longitudinal direction. As shown in FIG. 4A to FIG. 4F, the
press-forming apparatus 1' according to this embodiment manufacture the press-formed
article I 00' from a steel sheet S by relatively moving the die l 0 and the punch 20' in the
press-forming direction.
[0054]
(Steel sheet S)
The steel sheet S, as a workpiece sheet, may be for example a sheet having a
tensile strength of not less than 980 MPa, a length longer than 1700 mm in the
longitudinal direction, and a thickness of 0.8 to 2.3 mm. In this embodiment, as the steel
sheetS, a flat sheet with no particular shape, but a sheet may be pre-formed with a
particular shape.
[0055]
(Press-formed article 1 00')
The press-formed article 100' includes a substantially U shaped cross-section as
shown in FIG. 3, and has a top portion l Ol, a first sidewall portion 103 and a second
sidewall portion 105 which connect to ridge portions 1 02a, I 02b which are formed at both
23
ends of the top portion 101, and flange portions 107a, 107b which com1ect to bending
portions 1 06a, 1 06b formed at the first sidewall portion 103 and the second sidewall
portion l 05.
[0056]
(Punch 20')
The punch 20' is provided to face the die 10 in the vertical direction, and has a
first side face 20a which is formed with a shape corresponding to the first sidewall portion
103, a second side face 20b which is a face opposite to the first side face 20a and which is
formed with a shape corresponding to the second sidewall portion I 05, and a top face 20c
which faces the die 10.
Further, in this embodiment, the punch 20' has a ground face 20d which
externally extends in the horizontal direction from the first side face 20a and the second
side face 20b, and a lateral wall portion 20A which extends from the ground face 20d in
the upper direction.
[0057]
(Flange forming tools 30a, 30b)
The flange forming tools 30a, 30b are provided respectively on the punch 20' so
as to be movable in the horizontal direction. The upper face of the flange forming tool is
formed with a shape (recessed portion) corresponding to the bending portion 1 06a, 1 06b
and the flange portion 107a, 107b of the press-formed article 100'. Then, in the same
manner, a bottom end portion 13a of the first divisional die 13 and a bottom end portion
15a of the second divisional die 15 respectively have a shape corresponding to the bending
portions 106a, 106b, and the flange portions 107a, 107b. The bending portions 106a,
106b, and the flange portions 107a, 107b are fonned by pushing the bottom end portion
24
13a of the first divisional die 13 and the bottom end portion 15a of the second divisional
die 15 into an upper face of the flange forming tool.
[0058]
In the flange forming tools 30a, 30b, if a depth or a width of a recessed portion
formed in an upper face with an inner shape corresponding to the bending portions 1 06a,
106b, and flange portions 107a, 107b of the press-formed article 100' to be manufactured
is not within a proper range, the steel sheet S is warped at the time of forming the bending
portions I 06a, I 06b and the flange portions I 07a, I 07b, whereby a large deviation of a
stress distribution in the thickness direction is generated. This results in a generation of
the residual stress, and thus, due to inferior shape fixability, a failure occnrs in the bending
portions 106a, 106a and the flange portions 107a, 107b.
[0059]
Accordingly, it is preferable that the recessed portion formed in the upper face of
the flange forming tool 30a, 30b have a depth not more than 10 mm, and a width not less
than I 0 mm, in order to properly fonn the bending portions 1 06a, 1 06b, and the flange
portions 107a, 1 07b.
[0060]
A side face of the flange forming tools 30a, 30b, which does not face a side face
of the punch 20', is fixed with a flange fonning tool driving unit 30D.
A lower face of the flange fom1ing tool30a, 30b may be in surface to surface contact with
the ground face 20d ofthe punch.
The lower face of the flange forming tool30a, 30b, and/ or the upper face
(ground face 20d) of the punch 20' may be provided with a member for reducing a
frictional force, such as a linear guide member, wearing plate member, and a liner
member.
25
[0061]
(Flange forming tool driving unit 300)
The flange forming tool driving unit 300 has one end which is fixed to the lateral
wall portion 20A ofthe punch 20', and the other end which is fixed to the side face of the
flange forming tool 30a, 30b, which does not face the side face of the punch 20'. The
flange forming tool driving unit 300 is connected to a controlling unit not shown, and
moves the flange forming tool 30a, 30b in the horizontal direction between a position
interfering a stroke range of the first divisional die or the second divisional die, and a
position not interfering the stroke range. More specifically, the flange forming tool
driving unit 300 may be a pressing mechanism or an electrical motor that generates a gas
pressure, an oil pressure, an air pressure, spring pressure, or the like.
[0062]
(Press-forming method)
An example of the press-forming method using the press-forming apparatus I'
according to this embodiment will be explained with reference to FIG. 4A to FIG. 40.
[0063]
First, as shown in FIG. 4A, the flange forming tools 30a, 30b are provided at a
position interfering a stroke range of the first divisional die 13 and the second divisional
die 15, and place the steel sheetS on the flange forming tools 30a, 30b.
[0064]
Next, as shown in FIG. 4B, by lowering the die slide 11, the bottom end portion
13a of the first divisional die 13 and the bottom end portion l5a of the second divisional
die 15 are pushed into an upper face of the flange forming tools 30a, 30b formed with a
shape corresponding to the bending portions 1 06a, I 06b and the flange portions 1 07a,
1 07b, thereby fonning the bending portions 1 06a, 1 06b and the flange portions l 07a, I 07b.
26
If the top portion 101 does not have a planar shape, the top portion 101 may be
simultaneously formed by pushing the die pad 17 into the top face 20c of the punch 20' at
the time of forming the flange portions 107a, 1 07b.
[0065]
Next, as shown in FIG. 4C, the flange forming tools 30a, 30b are moved in the
horizontal direction so as to be located at a position not interfering the stroke range of the
first divisional die 13 and the second divisional die 15.
[0066]
Next, as shown in FIG. 40, the die slide 11 is lowered so as to form the first
sidewall portion l 03 by the first divisional die 13 and the first side face 20a of the punch
20'. At this timing, the second divisional die 15 and the punch 20' are separated from
each other in the vertical direction, and therefore, the second sidewall portion 105 is not
formed. However, it is preferable that the second sidewall portion 105 be pre-formed by
the lowering of the second divisional die 15, as the spring back ofthe second sidewall
portion 105 can be suppressed.
[0067]
Next, as shown in FIG. 4E, the die slide 11 is rose and a gap is formed between
the die slide 11 and both of the second divisional die 15 and the die pad 17. Then, the
insert block 19 is inserted into this gap, thereby positioning the base end portion 19a of the
insert block 19 between the die slide 11 and the second divisional die 15, and positioning
the tip end portion 19b of the insert block 19 between the die slide 11 and the die pad 17.
[0068]
Next, as shown in FIG. 4F, the die slide 11 is lowered in a state where the insert
block 19 is inserted, whereby the second sidewall I 05 is formed by the second divisional
27
die 15 and the second side face 20b of the punch 20'. The press-formed article 100' with
a hat type cross-section is thus obtained.
[0069]
It should be noted that, in the above example, the first sidewall portion 103 is
firstly formed and thereafter the second sidewall portion 105 is formed, however, it may
be possible that the second sidewall portion 105 is firstly formed and thereafter the first
sidewall portion 103 is formed. In this case, the second sidewall portion 105 is formed
and if necessary, the first sidewall portion 103 is pre-formed in a state where the insert
block 19 is inserted, and thereafter, the first sidewall portion 103 is formed in a state
where the insert block 19 is pulled out in the horizontal direction.
[0070]
By means of the press-forming apparatus I' according to the this embodiment,
because the insert block 19 movable in the horizontal direction is used, it is possible to
press form the first sidewall portion 1 03 and the second sidewall portion 105 at a different
timing, without increasing the size in the height direction ofthe press-forming apparatus
1 '. In addition, the top portion 101 can be clamped by the die pad 17 and the punch at a
time of press-forming the first sidewall portion 103 and at a time of press-forming the
second sidewall portion 105, therefore, the dimensional accuracy of the press-formed
article 100 can be improved.
In addition, since the flange forming tools 30a, 30b movable in the horizontal
direction are used, it is possible to manufacture the press-formed article 100' having hat
type cross-section without increasing the size oftl1e press-forming tool in the height
direction, by one set of forming tool (that is, without separately preparing a first forming
tool for forming the flange portions I 07a, 1 07b and a second forming tool for forming the
sidewall portions).
28
Accordingly, for example, by using a conventionall200 tons class press-forming
apparatus, it is possible to obtain a press-formed article 100' having a hat type
cross-section with high dimensional accuracy from a blank with a tensile strength of not
less than 980 MPa and a length oflonger than 1700 mm.
[0071]
(Third embodiment)
An example of the press-forming apparatus 1" according to the third embodiment
will be explained with reference to FIG. SA to FIG. 5F.
To simplify the explanation, members used in the press-forming apparatus 1
according to the first embodiment and the press-forming apparatus 1' according to the
second embodiment are applied with the same reference numeral, and the same
explanation is omitted.
[0072]
In this embodiment, the press-formed article 100' having a hat type cross-section
as shown in FIG. 3 is press-formed.
That is, as shown in FIG. SA to FIG. SF, the press-forming apparatus l"
according to this embodiment manufactures a press-formed article 100' from the steel
sheetS by relatively moving the die 10 and the punch 20" in the press-forming direction.
[0073]
(Punch 20")
The punch 20" is provided to face the die 10 in the vertical direction, and has a
first side face 20a which is formed with a shape corresponding to the first sidewall portion
103, a second side face 20b which is a face opposite to the first side face 20a and which is
formed with a shape corresponding to the second sidewall portion I 05, and a top face 20c
which faces the die I 0.
29
Further, in this embodiment, the punch 20" has a ground face 20d which
externally extends in the horizontal direction from the first side face 20a and the second
side face 20b, and a lateral wall portion 20A which extends from the ground face 20d in
the upper direction. In addition, a recessed portion is formed in the top face 20c of the
punch 20".
[0074]
(Punch pad 27)
A punch pad 27 is housed in the recessed portion formed in the top face 20c of
the punch 20", and includes an upper face having a shape corresponding to the top portion
1 01 and a lower face to which an upper end portion of a shaft 27 a extending in the vertical
direction is connected. The steel sheet S is press-formed in a state of being clamped
between the die pad 17 and the punch pad 27. The punch pad 27 is preferably configured
such that, in a state of fully housed in the recessed portion in the top face 20c of the punch
20", the end edge portions of the upper face of the punch pad 27 and the top face 20c of
the punch 20" are continued in a same plane. It should be noted that the shaft 27a is
provided so as to penetrate the punch 20" and the lower end portion of the shaft 27a is
connected to the punch pad driving unit 2 70.
As the punch pad 27, for example, a mechanism disclosed in WO 2013/094 705
may be used. By using this punch pad 27, at a time of starting a press-forming of the
ridge portions 1 02~ 1 02b, the first sidewall portion I 03, and a second sidewall portion
105 of the press-formed article 100', the steel sheetS is upwardly separated so as to be
high above the top face 20c ofthe punch 20", it is possible to significantly suppress the
generation of the spring back in the press-formed article 100'.
[0075]
(Punch pad driving unit 270)
30
The punch pad driving unit 27D is provided at an inner portion or a lower portion
of the punch 20", and is connected to a controlling unit not shown, so as to move the
punch pad 27 to clamp the steel sheetS between the punch pad 27 and the die pad 17 at
least when performing a press-forming.
More specifically, the punch pad driving unit 27D may be a pressing mechanism
or an electrical motor that generates a gas pressure, an oil pressure, an air pressure, spring
pressure, or the like.
[0076]
(Press-forming method)
An example of the press-forming method using the press-forming apparatus 1"
according to this embodiment will be explained with reference to FIG. 5A to FIG. 5F.
[0077]
First, as shown in FIG. SA, the flange fanning tools 30a, 30b are provided at a
position interfering a stroke range of the first divisional die 13 and the second divisional
die 15, and place the steel sheetS on the flange forming tools 30a, 30b. At this timing,
the punch pad 27 is posed in a state of standing above from the top face 20c of the punch
20" so as to contact with the steel sheetS, whereby the steel sheetS is upwardly separated
from the top face 20c ofthe punch 20".
[0078]
Next, as shown in FIG. 5B, by lowering the die slide 1 I, the bottom end portion
13a of the first divisional die 13 and the bottom end portion 15a of the second divisional
die 15 are pushed into an upper face of the flange forming tools 30a, 30b formed with a
shape corresponding to the bending portions 106a, 106b and the flange portions 107a,
1 07b, thereby forming the bending portions 1 06a, 1 06b and the flange portions 1 07a, 1 07b.
If the top portion 101 does not have a planar shape, the top portion 101 may be formed by
31
pushing the die pad 17 into fue punch pad 27 at the time offorming the bending portions
106a, 106b and the flange portions l07a, 107b.
[0079]
Next, as shown in FIG. 5C, the flange forming tools 30a, 30b are moved in fue
horizontal direction so as to be located at a position not interfering the stroke range of the
first divisional die 13 and the second divisional die.
[0080]
Next, as shown in FIG. 5D, the die slide 11 is lowered so as to form the first
sidewall portion 103 by the first divisional die 13 and the first side face 20a of the punch
20". At this timing, the second divisional die 15 and fue punch 20" are separated from
each other in the vertical direction, and therefore, the second sidewall portion 105 is not
formed. However, it is preferable that the second sidewall portion 105 be pre-formed by
the lowering of the second divisional die 15, as the spring back of the second sidewall
portion I 05 can be suppressed.
It should be noted that the movement in the vertical direction of the punch pad 27
is controlled such that a timing completing the pushing of the first divisional die 13 and a
timing fully housing the punch pad 27 in fue recessed portion offue punch 20" are the
same. That is, at the time when the press-formed article 100' is press-formed, the punch
pad 27 is pressed toward fue punch 20" gradually in the lower direction by being pushed
by the die pad 17, being housed in the recessed portion of the punch 20" at the
press-forming bottom dead point so as to have a co-plane with the top face 20c of the
punch 20". By controlling the movement of the punch pad 27 in the vertical direction in
this matmer, the generation of the spring back can be suppressed to improve the
dimensional accuracy.
[0081]
32
Next, as shown in FIG. 5E, the die slide 11 is rose and a gap is formed between
the die slide 11 and both of the second divisional die 15 and the die pad 17. Then, the
insert block 19 is inserted into this gap, thereby positioning the base end portion 19a of the
insert block 19 between the die slide II and the second divisional die 15, and positioning
the tip end portion 19b of the insert block 19 between the die slide 11 and the die pad 17.
[0082]
Next, as shown in FIG. SF, the die slide 11 is lowered in a state where the insert
block 19 is inserted, whereby the second sidewall 105 is fonned by the second divisional
die 15 and the second side face 20b of the punch 20". The press-fonued article 100'
with a hat type cross-section is thus obtained.
Here as well, the raising and lowering movements of the punch pad 27 is
controlled such that a timing completing the pushing of the second divisional die 15 and a
timing fully housing the punch pad 27 in tl1e recessed portion oftl1e punch are the same.
By controlling the movement in the vertical direction of the punch pad 27 in this manner,
it is possible to suppress the generation of the spring back to improve the dimensional
accuracy.
[0083]
It should be noted that, in the above exan1ple, the first sidewall portion 103 is
firstly formed and thereafterthe second sidewall portion 105 is formed, however, it may
be possible that the second sidewall portion 105 is firstly formed and thereafter the first
sidewall portion 103 is fonued. In this case, the second sidewall portion I 05 is fonued
and if necessary, the first sidewall portion I 03 is pre-formed in a state where the insert
block 19 is inserted, and thereafter, the first sidewall portion 103 is fonned in a state
where the insert block 19 is pulled out in the horizontal direction.
[0084]
33
By means of the press-forming apparatus I ' according to the this embodiment,
because the insert block 19 movable in the horizontal direction is used, it is possible to
press-fonn the first sidewall portion I 03 and the second sidewall portion 105 at a different
timing, without increasing the size in the height direction of the press-forming apparatus
1 '. In addition, the top portion I 01 can be clamped by the die pad 17 and the punch 20"
at a time of press-fanning the first sidewall portion 103 and at a time of press-forming the
second sidewall portion 105, therefore, the dimensional accuracy of the press-formed
article 1 00 can be improved.
In addition, since the flange fom1ing tools 30a, JOb movable in the horizontal
direction are used, it is possible to manufacture the press-formed article 100' having hat
type cross-section without increasing the size of the press-fanning tool in the height
direction, by one set of forming tool (that is, without separately preparing a first forming
tool for forming the flange portions I 07a, I 07b and a second forming tool for forming the
sidewall portions).
Further, at the time of forming the sidewall portion, the punch pad 27 is
controlled in the vertical direction, therefore, the spring back in the sidewall portion can
be suppressed. This makes it possible to improve the dimensional accuracy.
Accordingly, for example, by using a conventional 1200 tons class press-forming
apparatus, it is possible to obtain a press-formed article 100' having a hat type
cross-section with high dimensional accuracy from a blank with a tensile strength of not
less than 980 MPa and a length of longer than 1700 mm.
[0085]
FIG. 6 is a graph showing a relationship between a stroke and a forming load in a
case of manufacturing, by using a press-forming apparatus 1" of FIG. SA to FIG. SF, a
press-formed article 100' having a hat type cross-section from a steel sheet (thickness of
34
1.2 mm). The steel sheet has a tensile strength of not less than 980 MPa, and a total
length of longer than 1700 mm. In the press-formed article 100',
- the width of the top portion I 0 I is I 00 mm,
-the radius of curvature of the ridge portions 102a, 102b is 5.5 mm,
-the height of the first sidewall portion I 03 is 60 mm,
-the height of the second sidewall portion 105 is 90 mm,
- the radius of curvature of the bending portions I 06a, I 06b is 5.5 mm, and
- the width of the flange portions I 07 am 1 07b is 20 mm.
[0086]
The "stroke" indicated in the graph of FIG. 6 means a raising and lowering stroke
of the first divisional die 13 and the second divisional die 15, and the "forming load"
means the load applied to the die slide 11. Further, the "developed method'" indicated in
the graph ofF! G. 7 means a case of forming by the present invention, and the
"conventional method" means a case of forming by a pad-bending method.
[0087]
As shown in FIG. 6, according to the forming method by the press-forming
apparatus 1" of the third embodiment (development method), it can be confirmed that the
forming load can be reduced by 200 tons compared to the conventional method, and thus,
the press-formed a1tiC!e 100' having a hat type cross-section such as a side sill inner panel
or a side sill outer panel, with high strength and long size having a tensile strength of not
less than 980 MPa (preferably not less than 1180 MPa) and a total length oflonger than
1700 mm (preferably longer than 2000 mm) can be manufactured by one set
press-forming tool by using a 1200 tons class press-machine.
[0088]
35
Further, FIG. 7 is a graph showing a cushion stroke of the inner pad and an
amount ofthe spring back in this instance.
[0089]
As shown in a graph of FIG. 7, the opening an1ount is 1. 7 mm when the cushion
stroke of the punch pad 27 with respect to the shallower sidewall is 3 mm, and the opening
amount is -0.2 mm when the cushion stroke of the punch pad 27 with respect to the deeper
sidewall is 2 mm. Combining these amount, the total opening amount of the shallower
and deeper sidewall is 0.9 mm, therefore, according to the press-forming method by using
the press-forming apparatus according to the third embodiment (development method), it
can be confirmed that the spring back can be suppressed so as to be practically used
without a problem.
[0090]
The specific examples of the present invention have been explained above based
on the various embodiments and modifications, but the present invention should not be
only limited to these examples. The present invention includes various modifications of
the above specific examples.
[0091]
In the above explanation, as an example, the insert block 19 includes the base end
portion 19a and the tip end portion 19b. However, the insert block may not include the
tip end portion 19b. In this case, when the second sidewall portion I 05 is formed, a gap
is generated between the die slide 11 and die pad I 7, therefore, a pushing force may be
applied to the steel sheetS from a die pad by using a die pad driving unit 17D.
In the above explanation, as an example, the steel sheet is used as a workpiece
sheet. However, the workpiece sheet may be a plated steel sheet such as a galvanized
steel sheet or a galvannealed steel sheet, or may be a metallic sheet such as an aluminum
36
sheet or a titanium steel sheet, or a glass fiber strengthen resin sheet such as FRP or FRTP,
or a composite sheet thereof.
In the above explanation, the die 10 is lowered. However, the punch 20, 20',
20" may be rose, or both of the die 10 and the punch 20, 20', 20" may be both rose and
lowered so as to approach each other.
(0092]
In the above explanation, the insert block 19 is inserted between the second
divisional die 15 and the die slide 11, however, a configuration may be employed in which
another insert block (not shown) is inserted between the first divisional die 13 and the die
slide 11. In this case, a first divisional die driving unit (not shown) that drives the first
divisional die 13 is provided between the die slide ll and the first divisional die 13.
In the above explanation., the flange forming tools 30a, 30b are positioned so as to
contact the upper face of the ground face 20d of the punch 20', 20". However, if the
load offorming the flange portions 107a, 1 07b can be loaded, the flange forming tools 30a,
30b may not be positioned so as to be in contact with the upper face of the ground face
20d of the punch 20', 20".
In the above explanation., the height of the first sidewall portion 103 and the
height of the second sidewall portion I 05 are different. However, the height of the first
sidewall portion 103 and the height ofthe second sidewall portion 105 may be the same.
(0093]
In the above explanation, the flange forming tools 30a, 30b move in the
horizontal direction, but may move in the obliquely downward direction (in the direction
between the horizontal direction and the obliquely downward direction which inclines
from the horizontal direction by about 30 degrees). This makes it possible to start the
37
lowering of the die 10 when the flange forming tools 30a, 30b are being moved, and tbus,
the cycle time can be shortened.
In the above explanation, tbe flange portions 1 07a, 1 07b are formed on both sides
for the press-formed article 100' having a hat type cross-section. However, tbe flange
portion of the press-formed article may be fanned only at one side.
In the above explanation, the vertical direction is the press-forming direction.
However, a press-forming apparatus in which lateral direction is a press-forming
direction may be used.
[Industrial applicability]
[0094]
According to tbe above aspects, it is possible to manufacture a high strength
and/or long size press-formed article while suppressing tbe excessive amount of the
maximum press-fanning load and the excessive size of the press-forming apparatus in the
press-forming direction.
[Explanation of reference symbols]
[0095]
1, 1 ', 1 '' Press-forming apparatus
10 Die
11 Die slide
11A Suspending portion
13 First divisional die
13a Bottom end portion
15 Second divisional die
15a Bottom end portion
15D Second divisional die driving unit
17 Die pad
17D Die pad driving unit
19 Insert block
19a Base end portion
l9b Tip end portion
19D Insert block driving unit
20, 20', 20" Punch
20a First side face
20b Second side face
20c Top face
20d Ground face
20A lateral wall portion
27 Punch pad
27D Punch pad driving unit
30a, 30b Flange forming tool
30D Flange forming tool driving unit
100, 100' Press-formed article
101 Top portion
l 02a, 1 02b Ridge portion
103 First sidewall portion
I 05 Second sidewall portion
l 06a, 1 06b Bending portion
107a, 107b Flange portion
S Steel sheet

Claims
What is claimed is:
I. A press-forming apparatus for manufacturing a press-formed article from a workpiece
sheet by moving at least one of a die and a punch so as to be close to each other in a
press-forming direction, the press-formed article having a top portion, a first sidewall
portion, and a second sidewall portion, the first sidewall portion and the second sidewall
portion being connected to ridge portions formed on both edges of the top portion,
wherein the die comprises:
a die slide;
a first divisional die arranged at the die slide so as to be adjacent to a first side
face of the punch in a state where the die and the punch are the closest to each other;
a second divisional die arranged at the die slide so as to be adjacent to a second
side face of the punch in a state where the die and the punch are the closest to each other,
the second side face being an opposite side face of the first side face;
a second divisional die driving unit configured to move the second divisional die
in the press-forming direction so as to separate the second divisional die from the die
slide;
a die pad arranged between the first divisional die and the second divisional die;
a die pad driving unit configured to move the die pad in the press-forming
direction;
an insert block having a base end portion configured to be inserted between the
die slide and the second divisional die in a state where the die slide and the second
divisional die are separated from each other; and
an insert block driving unit configured to move the insert block in a direction
perpendicular to the press-forming direction.
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2. The press-forming apparatus according to claim I, wherein
the insert block has a tip end portion which extends from the base end portion to
the direction perpendicular to the press-forming direction, and which is configured to be
inserted between the die slide and the die pad in a state where the die slide and the die pad
are separated from each other, and
a thickness ofthe base end portion is thicker than a thickness of the tip end
portion.
3. The press-forming apparatus according to claim I or 2, wherein
the press-formed article has a flange portion which connects a bending portion
formed on an edge of at least one of the first sidewall portion and the second sidewall
portion.
4. The press-forming apparatus according to claim 3, comprising:
a flange forming tool arranged between tl1e die and the punch; and
a flange forming tool driving unit configured to move the flange forming tool
between a position where a stroke range ofthe first divisional die or the second divisional
die is interfered, and a position where a stroke range of the first divisional die or the
second divisional die is not interfered, wherein
an upper face of the flange forming tool and a lower face of at least one of the
first divisional die and the second divisional die have a shape corresponding to a face
shape of the bending portion and the flange portion.
5. The press-forming apparatus according to claim 4, wherein
the flange forming tool driving unit is configured to move the flange forming tool
into the direction perpendicular to the press-forming direction.
6. The press-forming apparatus according to claim 4 or 5, wherein
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a lower face of the flange forming tool is in surface-contact with a ground face of
the punch.
7. The press-forming apparatus according to any one of claims 1 to 6, comprising:
a punch pad configured to be housed in a recessed portion formed in a top face of
the punch, and
a punch pad driving unit configured to move the punch pad in the press-forming
direction.
8. The press-forming apparatus according to any one of claims 1 to 7, wherein
the first divisional die is formed integrally with the die slide.
9. The press-forming apparatus according to any one of claims l to 8, wherein
the die slide is connected to a single driving shaft.
10. The press-forming apparatus according to any one of claims 1 to 9, wherein
the workpiece sheet is a steel sheet.
11. The press-forming apparatus according to any one of claims 1 to 10, wherein
a tensile strength of the workpiece sheet is not less than 980 MPa.
12. The press-fonning apparatus according to any one of claims l to 11, wherein
a total length of the workpiece sheet is more than 1700 mm.
13. A press-forming method for manufacturing the press-formed article by using the
press-forming apparatus according to any one of claims 1 to 12, the press-forming method
compnsmg;
forming the first sidewall portion by moving the die slide toward the punch in a
state where the insert block is not inserted between the die slide and the second divisional
die; and
forming the second sidewall portion by moving the die slide toward the punch in
a state where the insert block is inserted between the die slide and the second divisional
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die.
14. The press-forming method according to claim 13, wherein
after performing the forming of the first sidewall portion, the insert block is
inserted between the die slide and the second divisional die, and the forming of the second
sidewall portion is performed.
15. The press-fonning method according to claim 14, wherein
in the forming of the first sidewall portion, a portion in the workpiece sheet
corresponding to the second sidewall portion is pre-formed by using the second divisional
die.
16. The press-forming method according to claim 13, wherein
after performing the forming of the second sidewall portion, the insert block is
pulled out from between the die slide and the second divisional die, and the forming of the
first sidewall portion is performed.
17. The press-forming method according to claim 16, wherein
in the forming of the second sidewall portion, a portion in the workpiece sheet
corresponding to the first sidewall portion is pre-formed by using the first divisional die.
18. The press-forming method according to any one of claims 13 to 17, wherein
before performing the forming of the first sidewall portion and the forming of the
second sidewall portion, the die slide is relatively moved toward the punch in a state
where a flange forming tool is arranged at a position interfering with a stroke range of the
first divisional die and the second divisional die, thereby forming a flange portion in the
workpiece sheet by using the flange forming tool and at least one of the first divisional die
and the second divisional die.
19. The press-forming method according to any one of claims 13 to 18, wherein
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in at least one of the fanning of the first sidewall portion and the forming of the
second sidewall portion, the die slide is lowered in a state where a punch pad configured
to be housed in a recess portion fonned in a top face of the punch is positioned high above
a top face of the punch, and the punch pad is lowered in accordance with the lowering of
the die slide to complete a press-forming.