TECHNICAL FIELD
[0001]
The present invention relates to a method for manufacturing a press component,
and an apparatus for manufacturing a press component.
BACKGROUND ART
[0002]
The body shell of an automobile has a unit construction structure (monocoque
structure). A unit construction structure is constituted by a number of framework
members and formed panels that are joined together.
[0003]
For example, a front pillar, a center pillar, a side sill, a roof rail and a side
member are known as framework members. Further, for example, a hood ridge, a dash
panel, a front floor panel, a rear floor front panel and a rear floor rear panel are known
as formed members.
[0004]
Framework members that have a closed cross-section such as a front pillar, a
center pillar and a side sill are assembled by joining configuration members such as a
front pillar reinforcement, a center pillar reinforcement and a side sill outer
reinforcement to other configuration members such as an outer panel and an inner panel.
[0005]
Figure 14 is an explanatory drawing that illustrates an example of a framework
member 1.
(0006]
As illustrated in Figure 14, a framework member 1 is assembled by joining
configuration members 2, 3, 4 and 5 together by spot welding. The configuration
2
member 2 has a substantially hat-shaped cross-sectional shape. The substantially
hat-shaped cross-sectional shape includes a top plate 2a, a pair of left and right vertical
walls 2b and 2b, and flanges 2c and 2c that connect with the vertical walls 2b and 2b.
The top plate 2a has an inverted L-shaped external shape in plan view as viewed from a
direction orthogonal to the top plate 2a.
[0007]
Note that, a configuration member also exists that has an L-shaped external
shape that is opposite to the shape of the aforementioned configuration member 2
illustrated in Figure 14 in plan view. In the following description, a component having
the aforementioned L-shaped or inverted L-shaped external shape in plan view is
referred to generically as an "L-shaped component". The strength and rigidity of the
framework member 1 are secured by having an L-shaped component as a constituent
element.
[0008]
Figure 15 is an explanatory drawing illustrating an example of a T -shaped
component 6. A top plate 6a of the T-shaped component 6 has aT-shaped external
shape in plan view when viewed from a direction that is orthogonal to the top plate 6a.
For example, a center pillar reinforcement is known as the T-shaped component 6.
[0009]
Similarly to the L-shaped component 2, the T -shaped component 6 has a
substantially hat-shaped cross-sectional shape. The substantially hat-shaped
cross-sectional shape has a top plate 6a, a pair of left and right vertical walls 6b and 6b,
and a pair of left and right flanges 6c and 6c. In addition, a Y-shaped component (refer
to Figure 13 that is described later) is known as a modification of the T-shaped
component 6. A top plate 6a of the Y -shaped component has an external shape that is
a Y -shape in the aforementioned plan view. In the following description, the L-shaped
component 2, the T -shaped component 6 and the Y -shaped component are referred to
generically as "curved component".
[0010]
A curved component is usually manufactured by press working by draw
3
forming in order to prevent the occurrence of wrinkling.
[0011]
Figures 16(a) and 16(b) are explanatory drawings illustrating an outline of
press working by draw forming, in which Figure 16(a) illustrates a state prior to the start
of forming, and Figure 16(b) illustrates a state when forming is completed (bottom dead
center of forming).
[0012]
As illustrated in Figure 16(a) and Figure 16(b), press working by draw forming
is performed on a blank 10 using a die 7, a punch 8 and a blank holder 9 to form an
intermediate press component 12.
[0013]
Figure 17 is an explanatory drawing illustrating an example of a press
component 11 manufactured by press working by draw forming. Figure 18 is an
explanatory drawing illustrating a blank 10 that is the forming starting material for the
press component 11. Figure 19 is an explanatory drawing illustrating a wrinkle
suppression region lOa of the blank 10. Figure 20 is an explanatory drawing
illustrating an intermediate press component 12 as it is in a state in which press working
has been performed thereon.
[0014]
The press component 11 illustrated in Figure 17 is manufactured by press
working by draw forming through, for example, the processes (i) to (iv) that are listed
hereunder.
[0015]
(i) The blank 10 illustrated in Figure 18 is disposed between the die 7 and the
punch 8.
[0016]
(ii) The wrinkle suppression region 1 Oa (hatched region in Figure 19) at the
periphery of the blank 10 is firmly held by the die 7 and the blank holder 9 as illustrated
in Figure 16(a) and Figure 16(b). By this means, excessive inflow of the blank 10 into
the press mold is suppressed.
4
[0017]
(iii) By moving the die 7 and the punch 8 relatively to each other in a pressing
direction (vertical direction) in which the die 7 and the punch 8 approach each other as
illustrated in Figure 16(b ), press working by draw forming is performed on the blank 10
to form the intermediate press component 12.
(iv) By cutting off (trimming) the wrinkle suppression region lOa (a cutting-off
region that is an unrequired portion) around the intermediate press component 12, the
press component 11 illustrated in Figure 17 is obtained.
[0018]
As illustrated in Figures 17 to 20, in the press working by draw forming,
excessive inflow of the blank 10 into the press mold is suppressed by the blank holder 9.
Therefore, the occurrence of wrinkles in the intermediate press component 12 that are
caused by excessive inflow ofthe blank 10 is suppressed.
[0019]
However, the occurrence of the cutting-off region that is an unrequired portion
around the intermediate press component 12 is unavoidable. Consequently, the yield
of the press component 11 decreases and the manufacturing cost of the press component
11 rises.
[0020]
Figure 21 is an explanatory drawing illustrating an example of the state of
occurrence of pressing defects (wrinkling and cracking) in the intermediate press
component 12.
[0021)
As illustrated in Figure 21, in the intermediate press component 12, wrinkling
is liable to occur at a regions where the blank 10 is liable to excessively flow into the
press mold during the draw forming process, and cracking is liable to occur at p regions
where there is a partial reduction in sheet thickness during the draw forming process.
[0022]
In particular, when it is attempted to manufacture a curved component by
performing pressing working by draw forming on the blank 10 that is made from a high
5
strength steel sheet with low ductility, wrinkling and cracking are liable to occur in the
intermediate press component 12 due to insufficient ductility of the blank 10.
[0023]
To prevent the occurrence of such wrinkling and cracking in the intermediate
press component 12, conventionally a steel sheet that has excellent ductility but
comparatively low strength has been used as the blank 10 for the curved component.
Consequently, to secure the strength required for the curved component, it has been
necessary to make the sheet thickness of the blank 10 thick, making an increase in the
weight and an increase in the manufacturing cost of the curved component unavoidable.
[0024]
The present applicants have previously disclosed, in Patent Document 1, a
patented invention relating to a method that, even when using a blank made from a high
tensile strength steel sheet having low ductility, enables press working of a curved
component by bending forming with a good yield, and without wrinkling or cracking
occurring. In the present description, the method relating to the aforementioned
patented invention is also referred to as "free bending method".
[0025]
Hereunder, the aforementioned patented invention will be described referring
to the aforementioned Figure 17 and Figure 22. Figure 22 is an explanatory drawing
that partially illustrates an outline of the patented invention disclosed by Patent
Document 1.
[0026]
The patented invention disclosed by Patent Document 1 manufactures a press
component 11 by performing cold or warm press working by bending forming on a
blank. As illustrated in Figure 17, the press component 11 has a cross-sectional shape
(for example, a hat-shaped cross-sectional shape) that includes a top plate lla, convex
ridge lines 11 b, 11 b, vertical walls 11 c, 11 c, concave ridge lines 11 d, 11 d, and flanges
lle, 11e.
[0027]
The top plate lla extends in first direction (direction indicated by an arrow in
6
Figure 17). The convex ridge lines 11 b, 11 b are connected to the two ends in the width
direction (direction orthogonal to the first direction) of the top plate 11 a, respectively.
The vertical walls 11 c, 11 c are connected to the convex ridge lines 11 b, 11 b,
respectively. The concave ridge lines lld, lld are connected to the vertical walls llc,
11c, respectively. The flanges lle, lle are connected to the concave ridge lines lld,
11d, respectively.
[0028]
The press component 11 also has a curved portion 13 that curves in a plan view
that is ortho genal to the top plate 11 a, and by this means the press component 11 has an
external shape that is an inverted L-shape.
[0029]
According to the free bending method, as illustrated in Figure 22, a blank 18 is
disposed between a die 15 and a die pad 16, and a punch 17 of a press-forming machine
14 that employs bending forming.
[0030]
By (i) the die pad 16 applying a pressure that is 1.0 MPa or more and less than
32.0 MPa to a portion (vicinity of a portion at which the curved portion 13 of the press
component 11 is to be formed) 18a of a portion at which the top plate 11 a is to be
formed in the blank 18, or (ii) the die pad 16 being brought adjacent to or into contact
with the punch 1 7 so that the distance of a gap between the die pad 16 and the punch 1 7
satisfies the condition of being within a range of {sheet thickness of blank 18 x (1.0 to
1.1)}, the press component 11 is manufactured by performing press working as
described hereunder while suppressing out-of-plane deformation at the portion 18a of
the portion at which the top plate 11 a is to be formed.
[0031]
1n a state in which a portion (portion corresponding to the base of the inverted
L-shape) of the blank 18 to be formed into an end portion 11 fin the extending direction
of the top plate 11 a is present on the same plane as a portion of the blank 18 to be
formed into the top plate lla, the die 15 and the punch 17 are moved relative to each
other in directions in which the die 15 and the punch 17 approach each other.
7
[0032]
By this means, while causing the portion (portion corresponding to the base of
the inverted L-shape) of the blank 18 to be formed into the end portion 11 f to move
in-plane (slide) over the portion of the die 15 at which top plate lla will be formed, the
vertical wall llc, concave ridge line lid and flange lle on the inner circumferential
side of the curved portion 13 are formed.
[0033]
In this way, when manufacturing the press component 11 having the curved
portion 13 by performing press working on the blank 18, during the press working, the
inflow amount of the portion of the blank 18 to be fanned into the end portion 11 fin the
extending direction of the top plate 11 a that flows into the portion of the blank 18 to be
formed into the vertical wall llc increases.
[0034]
Consequently, according to the free bending method, excessive tensile stress at
the flange 11 e (in the conventional press working by draw forming, a region where
cracking is liable to occur due to a reduction in the sheet thickness) on the inner
circumferential side of the curved portion 13 is reduced, and the occurrence of cracking
is suppressed.
[0035]
Further, according to the free bending method, at the top plate 11 a (in the
conventional press working by draw forming, a region where wrinkling is liable to
occur due to excessive inflow of the blank 18) also, because the blank 18 is pulled, the
occurrence of wrinkling is suppressed.
[0036]
Further, according to the free bending method, a wrinkle suppression region
(cutting-off region) that must be provided in the blank 18 when performing the
conventional press working by draw forming is not required. Therefore, the yield of
the press component 11 improves.
[0037]
In addition, the free bending method employs press working by bending
8
forming. Therefore, the ductility required for the blank 18 in the free bending method
is less than the ductility required for a blank when performing press working by draw
forming. Accordingly, it is possible to use a high strength steel sheet with
comparatively low ductility as the blank 18, and the sheet thickness of the blank 18 can
be set to a small thickness, and thus a reduction in the weight of a vehicle can be
achieved.
[0038]
In Patent Document 2, the present applicants disclosed an invention in which
an excess portion of a specific shape is provided at an edge section of a portion to be
formed into the flange 11 e on the inner circumferential side of the curved portion 13 in
a developed blank that is used in the free bending method.
[0039]
According to the invention disclosed by Patent Document 2, while further
enhancing the formability of the vicinity of the curved portion 13 and preventing
cracking of the flange 11 e on the inner circumferential side of the curved portion 13 by
means of the free bending method, excessive inflow of the blank 18 from a portion of
the blank 18 to be formed into the top plate 11 a to a portion of the blank 18 to be
formed into the vertical wall 11 c can also be suppressed, and cracking in the end portion
of the top plate 11 a can also be prevented.
LIST OF PRIOR ART DOCUMENTS
PATENT DOCUMENT
[0040]
Patent Document 1: WO 2011/145679
Patent Document 2: WO 2014/185428
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0041]
The present inventors conducted intensive studies to further enhance the
9
formability of the free bending method, and as a result newly found that even when
press working is performed on the blank 18 by the free bending methods disclosed in
Patent Documents 1 and 2, in some cases the press component 11 cannot be
manufactured without defective forming occurring.
[0042]
As such cases, for example, the following first case and second case may be
mentioned. That is, the first case is a case that satisfies at least one of the following
conditions:
(a) the blank 18 is made from an ultra-high tensile strength steel sheet having a
tensile strength of 1180 MPa or more,
(b) a height (projection distance in a product height direction of the vertical
wall 11 c) of the press component 11 is a high height of 70 mm or more,
(c) a radius of curvature R1 of the concave ridge line lld of the press
component 11 is a small value of 10 mm or less in side view, and
(d) a radius of curvature Rz of the curved portion 13 of the press component 11
is a small value of 1 00 mm or less in plan view;
and the second case is a case that satisfies at least two or more of the following
conditions:
(e) the blank 18 is made from an ultra-high tensile strength steel sheet having a
tensile strength of 1180 MPa or more,
(f) the height (projection distance in the product height direction of the vertical
wall 11 c) of the press component 11 is 55 mm or more,
(g) the radius of curvature R1 of the concave ridge line lld of the press
component 11 is 15 mm or less in side view, and
(h) the radius of curvature Rz on the inner side of the curved portion 13 of the
press component 11 is 140 mm or less in plan view.
In the first case or second case, even if the free bending method is used, cracking occurs
in the flange lle on the inner circumferential side of the curved portion 13.
[0043]
The present invention has been conceived to solve these new problems of the
10
inventions disclosed in Patent Documents 1 and 2. An objective of the present
invention is to provide a manufacturing method and a manufacturing apparatus for
manufacturing a press component, which can manufacture a curved component without
generating cracking in a flange on an inner circumferential side of the curved portion
even when press working by the free bending method is performed on a blank in the
aforementioned first case or second case.
SOLUTION TO PROBLEM
[0044]
The present inventors conducted intensive studies to solve the above described
problem, and as a result obtained the findings A to D described hereunder to thereby
complete the present invention.
[0045]
(A) As has been described referring to Figure 17 and Figure 22, in the free
bending method, a portion (portion corresponding to the base of the inverted L-shape)
of the blank 18 to be formed into the end portion 11 f in the extending direction of the
top plate II a flows in towards a portion of the blank 18 to be formed into the vertical
wall llc on the inner circumferential side of the curved portion 13. By this means, in
the blank 18, material is supplied to a portion to be formed into the flange 11 e on the
inner circumferential side of the curved portion 13.
[0046]
Therefore, by increasing the amount by which the portion of the blank 18 to be
formed into the end portion 11 fin the extending direction of the top plate 11 a flows into
the portion of the blank 18 to be formed into the vertical wall llc on the inner
circumferential side of the curved portion 13, the occurrence of cracking in the flange
lle on the inner circumferential side of the curved portion 13 can be prevented, and it is
thus possible to raise the forming limit of the free bending method.
[0047]
(B) However, when performing press working, a limit of the aforementioned
inflow amount is geometrically determined according to the amount of change in a
II
cross-section line length of the flange 11e between before and after forming of a
cross-section in the inflow direction. Further, the limit of the inflow amount serves as
the forming limit in the free bending method.
[0048]
(C) When performing press-forming, the aforementioned inflow amount can be
increased by, for example, forming, at the same time as the press-forming, a material
inflow facilitating portion such as a bead in the vicinity (preferably, in the blank 18, a
region that is outside a region to be formed into the press component 11) of a portion of
the blank 18 to be formed into the flange 11 e on the inner circumferential side of the
curved portion 13.
[0049]
(D) By making the shape of the material inflow facilitating portion a shape that
can secure a cross-section line lengtn difference in an inflow direction of the material
(in the blank 18, the maximum principal strain direction of a deformation of a portion to
be formed into the flange lle on the inner circumferential side of the curved portion 13),
the aforementioned inflow amount can be increased, and by this means the forming
limit in the free bending method can be raised.
[0050]
The present invention is as described hereunder.
[0051]
( 1) A method for manufacturing a press component, by performing press
working on a blank or a pre-formed blank disposed between a die and a die pad, and a
punch that is disposed facing the die and die pad, which constitute a press-forming
apparatus that employs bending forming,
the press component having a cross-sectional shape constituted by a top plate
extending in a first direction, a convex ridge line connecting to an end portion of the top
plate in a direction orthogonal to the first direction, a vertical wall connecting to the
convex ridge line, a concave ridge line connecting to the vertical wall, and a flange
connecting to the concave ridge line, and also having a curved portion that, with the
convex ridge line, the vertical wall and the concave ridge line curving, provides an
12
external shape of the top plate with an L-shape, a T -shape or a Y -shape in a plan view
that is orthogonal to the top plate,
the method comprising, when manufacturing the press component:
weakly pressing a portion of the blank to be formed into a part of the top plate
of the curved portion by the die pad, or subjecting the die pad to approach or come in
contact with a portion of the blank to be formed into a part of the top plate of the curved
portion while maintaining a gap between the die pad and the punch at a distance that is
not less than a sheet thickness of the blank and not more than 1.1 times the sheet
thickness of the blank, and
forming, in a state in which a portion of the blank to be formed into an end
portion of the top plate in the first direction is present on a same plane as the portion of
the blank to be formed into the top plate, the vertical wall, the concave ridge line and
the flange on an inner circumferential side of the curved portion while causing the
portion of the blank that is to be formed into the end portion of the top plate in the first
direction to move in-plane over a portion of the die at which the top plate will be
formed by relatively moving the die and the punch in directions in which the die and the
punch approach each other,
wherein,
by the press working, in a vicinity of a portion of the blank to be formed into a
flange on the inner circumferential side of the curved portion of the press component,
one or more material inflow facilitating portions are provided, the material inflow
facilitating portions increasing an inflow amount by which the portion of the blank to be
formed into the end portion flows into the portion of the blank to be formed into the
flange on the inner circumferential side of the curved portion, and
the material inflow facilitating portion includes, in a plan view orthogonal to
the top plate, a cross-sectional shape in which a cross-section line length in a
cross-section parallel to a straight line that is tangent to a middle position of an inner
circumference of the curved portion increases with distance from the flange on the inner
circumferential side of the curved portion.
[0052]
13
(2) The method for manufacturing a press component described in item (1)
above, wherein the method satisfies at least one of the following conditions:
the blank comprises an ultra-high tensile strength steel sheet having a tensile
strength of 1180 MPa or more;
a projection distance of the vertical wall in a product height direction as a
height of the press component is 70 mm or more;
a radius of curvature of the concave ridge line of the press component is 10
mm or less in side view; and
a radius of curvature on the inner circumferential side of the curved portion in
the press component is 100 mm or less in the plan view.
[0053]
(3) The method for manufacturing a press component described in item (1)
above, wherein the method satisfies two or more of the following conditions:
the blank comprises an ultra-high tensile strength steel sheet having a tensile
strength of 1180 MPa or more;
a projection distance of the vertical wall in a product height direction as a
height of the press component is 55 mm or more;
a radius of curvature of the concave ridge line of the press component is 15
mm or less in side view, and
a radius of curvature on an inner side of the curved portion in the press
component is 140 mm or less in the plan view.
[0054]
( 4) The method for manufacturing a press component described in any one of
items (1) to (3) above, wherein:
in the blank, the material inflow facilitating portion is provided at a region that
is outside of a region to be formed into the press component.
[0055]
(5) The method for manufacturing a press component described in any one of
items (1) to (4) above, wherein:
the cross-sectional shape includes a case where the cross-section line length is
14
partially constant.
[0056]
( 6) The method for manufacturing a press component described in any one of
items (1) to (5) above, wherein:
the material inflow facilitating portion is a convex bead that is convex toward a
same side as the top plate of the press component, or is a concave bead that is convex
toward an opposite side to the top plate of the press component.
[0057]
(7) The method for manufacturing a press component described in any one of
items (1) to (6) above, wherein:
the material inflow facilitating portion is provided at least in a region in which
the blank is present.
[0058]
(8) The method for manufacturing a press component described in any one of
items (1) to (7) above, wherein:
the material inflow facilitating portion is provided in a stepped shape in a
direction parallel to a sheet thickness direction of the blank.
[0059]
(9) The method for manufacturing a press component described in any one of
items (1) to (8) above, wherein:
the material inflow facilitating portion has an external shape obtained by
connecting a meeting point of the concave ridge line and the flange in the curved
portion that is formed, and an end portion of the blank at a time when the forming starts.
[0060]
( 1 0) The method for manufacturing a press component described in any one of
items (1) to (9) above, wherein:
the cross-sectional shape is a hat-shaped cross-sectional shape constituted by:
a top plate extending in a first direction,
two convex ridge lines connecting to both end portions of the top plate
in a direction orthogonal to the first direction,
15
two vertical walls connecting to the two convex ridge lines,
respectively,
two concave ridge lines connecting to the two vertical walls,
respectively, and
two flanges connecting to the two concave ridge lines, respectively.
[0061]
(11) An apparatus for manufacturing a press component, that comprises a die
and a die pad, and a punch that is disposed facing the die and die pad, and that:
by perfotming press working on a blank or a pre-formed blank that is disposed
between the die and die pad and the punch,
manufactures a press component having a cross-sectional shape constituted by
a top plate extending in a first direction, a convex ridge line connecting to an end
portion in a pirection orthogonal to the first direction of the top plate, a vertical wall
connecting to the convex ridge line, a concave ridge line connecting to the vertical wall,
and a flange connecting to the concave ridge line, and also having a curved portion that,
with the convex ridge line, the vertical wall and the concave ridge line curving, provides
an external shape of the top plate with an L-shape, T-shape or Y-shape in a plan view
that is orthogonal to the top plate,
the apparatus manufacturing the press component by:
the die pad weakly pressing a portion of the blank to be fotmed into a part of
the top plate of the curved portion, or the die pad approaching or contacting with a
portion of the blank to be formed into a part of the top plate of the curved portion while
maintaining a gap between the die pad and the punch at a distance that is not less than a
sheet thickness of the blank and not more than 1.1 times the sheet thickness of the blank,
and
in a state in which a portion of the blank to be formed into an end portion in the
first direction of the top plate is present on a same plane as the portion of the blank to be
formed into the top plate, by the die and the punch moving relatively in directions in
which the die and the punch approach each other, forming the vertical wall, the concave
ridge line and the flange on an inner circumferential side of the curved portion while
16
causing the portion of the blank to be formed into the end portion to move in-plane over
a portion of the die at which the top plate will be formed;
wherein:
the die and the punch comprise a material inflow facilitating portion forming
mechanism that, by means of the press working, in a vicinity of a portion of the blank to
be formed into a flange on an inner circumferential side of the curved portion of the
press component, provides one or more material inflow facilitating portions that
increase an amount by which a portion of the blank to be formed into the end portion
flows into the portion of the blank to be formed into the flange on the inner
circumferential side of the curved portion; and
the material inflow facilitating portion forming mechanism provides the
material inflow facilitating portion in a manner so that, in a plan view that is orthogonal
to the top plate, a cross-section line length of the material inflow facilitating portion at a
cross-section that is parallel to a straight line that is tangent to a center position of an
inner circumference of the curved portion increases with distance from the flange on the
inner circumferential side of the curved portion.
[0062]
(12) The apparatus for manufacturing a press component described in item (11)
above, the apparatus for manufacturing a press component according to claim 11,
wherein the apparatus satisfies at least one of the following conditions:
the blank comprises an ultra-high tensile strength steel sheet having a tensile
strength of 1180 MPa or more;
a projection distance of the vertical wall in a product height direction as a
height of the press component is 70 mm or more;
a radius of curvature of the concave ridge line of the press component is 10
mm or less in side view; and
a radius of curvature on the inner circumferential side of the curved portion in
the press component is 100 mm or less in the plan view.
[0063]
(13) The apparatus for manufacturing a press component described in item (11)
17
above, wherein the apparatus satisfies two or more of the following conditions:
the blank comprises an ultra-high tensile strength steel sheet having a tensile
strength of 1180 MPa or more;
a projection distance of the vertical wall in a product height direction as a
height of the press component is 55 mm or more;
a radius of curvature of the concave ridge line of the press component is 15
mm or less in side view, and
a radius of curvature on an inner side of the curved portion in the press
component is 140 mm or less in the plan view.
[0064]
(14) The apparatus for manufacturing a press component described in any one
of items (11) to (13) above, wherein:
the material inflow facilitating portion forming mechanism provides the
material inflow facilitating portion at a region of the blank that is outside of a region to
be formed into the press component.
[0065]
(15) The apparatus for manufacturing a press component described in any one
of items (11) to (14) above, wherein:
the cross-sectional shape includes a case where the cross-section line length is
partially constant.
[0066]
(16) The apparatus for manufacturing a press component described in any one
of items (11) to (15) above, wherein:
the material inflow facilitating portion is a convex bead that is convex toward a
same side as the top plate of the press component, or is a concave bead that is convex
toward an opposite side to the top plate of the press component.
[0067]
(17) The apparatus for manufacturing a press component described in any one
of items (11) to (16) above, wherein:
the material inflow facilitating portion forming mechanism provides the
18
material inflow facilitating portion in at least a region in which the blank is present.
[0068]
(18) The apparatus for manufacturing a press component described in any one
of items (11) to (17) above, wherein:
the material inflow facilitating portion forming mechanism provides the
material inflow facilitating portion in a stepped shape in a direction parallel to a sheet
thickness direction of the blank.
[0069]
(19) The apparatus for manufacturing a press component described in any one
of items (11) to (18) above, wherein:
the material inflow facilitating portion forming mechanism provides the
material inflow facilitating portion so as to have an external shape obtained by
connecting a region of the blank to be formed into a meeting point between the concave
ridge line and the flange of the curved portion, and an end portion of the blank prior to
the forming.
[0070]
(20) The apparatus for manufacturing a press component described in any one
of items (11) to (19) above, wherein:
the cross-sectional shape is a hat-shaped cross-sectional shape
constituted by:
a top plate extending in a first direction,
two convex ridge lines connecting to both end portions of the top plate
in a direction orthogonal to the first direction,
two vertical walls connecting to the two convex ridge lines,
respectively,
two concave ridge lines connecting to the two vertical walls,
respectively, and
two flanges connecting to the two concave ridge lines, respectively.
ADVANTAGEOUS EFFECTS OF INVENTION
[0071]
19
According to the present invention, even when press working by a free bending
method is performed on a blank in the aforementioned first case or second case, an
inflow amount of material can be increased and a forming limit can be raised in
comparison to the free bending methods disclosed by Patent Documents 1 and 2, and it
is thus possible to manufacture a press component without generating cracking in a
flange on an inner circumferential side of a curved portion of a press component.
BRIEF DESCRIPTION OF DRAWINGS
[0072)
[Figure 1] Figure 1 is an explanatory drawing illustrating a configuration example of a
manufacturing apparatus according to the present invention.
[Figure 2] Figure 2 is an explanatory drawing partially illustrating an example of a press
component that was press-formed by the manufacturing apparatus according to the
present invention.
[Figure 3] Figure 3 is an explanatory drawing illustrating the positional relationship
between a material inflow facilitating portion forming mechanism and a concave ridge
line forming portion of the manufacturing apparatus according to the present invention
and a blank.
[Figure 4] Figure 4 is an explanatory drawing illustrating a cross-section in a
conventional punch in which a material inflow facilitating portion forming mechanism
is not provided, that corresponds to a cross-section A-A in Figure 1.
[Figure 5] Figure 5 is an explanatory drawing illustrating the positional relationship
between a material inflow facilitating portion forming mechanism and a concave ridge
line forming portion of the manufacturing apparatus according to the present invention
and a blank, and the locations of cross-sections B, C and D.
[Figure 6] Figure 6 is a graph illustrating cross-section line length differences with
respect to a conventional punch at a flange forming portion of a punch at the
cross-sections B, C and D.
[Figure 7] Figure 7 is an explanatory drawing illustrating a cross-section A-A of a punch
in which a material inflow facilitating portion forming mechanism is provided.
20
[Figure 8] Figure 8 is an explanatory drawing illustrating the positional relationship
between a material inflow facilitating portion forming mechanism and a concave ridge
line forming portion of the manufacturing apparatus according to the present invention
and a blank, and the locations of cross-sections B, C and D.
[Figure 9] Figure 9 is an explanatory drawing that shows the reason why cracking at a
portion "a" of a blank is prevented by providing a material inflow facilitating portion
forming mechanism constituted by a recess and a protrusion in a die and punch.
[Figure 1 0] Figure 1 O(a) to Figure 1 O(t) are explanatory drawings that partially illustrate
examples of the shapes of protrusions or recesses that are constituent elements of
various kinds of material inflow facilitating portion forming mechanisms that are
provided in a punch.
[Figure 11] Figure ll(a) and Figure 11(b) are explanatory drawings that respectively
illustrate another press component manufactured by the present invention.
[Figure 12] Figure 12 is an explanatory drawing illustrating an intermediate component
(example embodiment of the present invention) for aT-shaped component.
[Figure 13] Figure 13 is an explanatory drawing illustrating an intermediate component
(example embodiment of the present invention) for a Y -shaped component.
[Figure 14] Figure 14 is an explanatory drawing illustrating an example of a framework
member.
[Figure 15] Figure 15 is an explanatory drawing illustrating an example of aT-shaped
component.
[Figure 16] Figures 16( a) and Figure 16(b) are explanatory drawings illustrating an
outline of press working by draw forming, in which Figure 16(a) illustrates a state prior
to the start of forming, and Figure 16(b) illustrates a state when forming is completed
(bottom dead center of forming).
[Figure 17] Figure 17 is an explanatory drawing illustrating an example of a press
component manufactured by press working by draw forming.
[Figure 18] Figure 18 is an explanatory drawing illustrating a blank that is a forming
starting material for a press component.
[Figure 19] Figure 19 is an explanatory drawing illustrating a wrinkle suppression
21
region of a blank.
[Figure 20] Figure 20 is an explanatory drawing illustrating an intermediate press
component as it is in a state in which press working has been performed thereon.
[Figure 21] Figure 21 is an explanatory drawing illustrating an example of the state of
occurrence of pressing defects in an intermediate press component.
[Figure 22] Figure 22 is an explanatory drawing that partially illustrates an outline of
the patented invention disclosed by Patent Document 1.
REFERENCE SIGNS LIST
[0073]
11 Press component
11 a Top plate
11e Flange
llfEnd portion
13 Curved portion
19 Material inflow facilitating portion
20 Press-forming apparatus
21 Die
22 Die pad
23 Punch
24 Blank
25 Material inflow facilitating portion forming mechanism
DESCRIPTION OF EMBODIMENTS
[0074]
The manufacturing apparatus and manufacturing method according to the
present invention are described hereunder.
[0075]
In the following description, a case in which a press component 11 to be
manufactured by the present invention is an L-shaped component in which a top plate
22
11a has an external shape that is an inverted L-shape in a plan view that is orthogonal to
the top plate lla is taken an example. However, objects to be manufactured by the
present invention are not limited to an L-shaped component, and also include other
curved components (T-shaped component andY-shaped component).
[0076]
Further, in the following description, a case in which the press component 11
and an intermediate component 11-1 have a hat-shaped cross-sectional shape constituted
by the top plate lla, two convex ridge lines llb, llb, two vertical walls llc, llc, two
concave ridge lines 11 d, 11 d and two flanges 11 e, 11 e is taken as an example.
However, objects to be manufactured by the present invention are not limited to the
press component 11 and the intermediate component 11-1 that have a hat-shaped
cross-sectional shape, and also include intermediate components 11-2 and 11-3 for press
components having the cross-sectional shapes shown in Figure 11 set forth below.
[0077]
1. Manufacturing apparatus 20 of the present invention
Figure 1 is an explanatory drawing illustrating a configuration example of a
manufacturing apparatus 20 according to the present invention. Figure 2 is an
explanatory drawing partially illustrating an example of an intermediate component
11-1 of a press component 11 that was press-formed by the manufacturing apparatus 20.
[0078]
As illustrated in Figure 1, the manufacturing apparatus 20 is a press-forming
apparatus that employs bending forming and that uses the free bending method.
[0079]
The manufacturing apparatus 20 includes a die 21, a die pad 22 and a punch 23.
The punch 23 is disposed facing the die 21 and the die pad 22. The die pad 22 is
movable up and down together with the die 21, and can also press a part of a blank 24.
[0080]
The manufacturing apparatus 20 manufactures the intermediate component
11-1 of the press component 11 having the external shape illustrated in Figure 2 by
performing press working as cold or warm working on the blank (developed blank) 24
23
or on a blank (not illustrated in the drawings) which was subjected to preforming that is
minor processing (for example, embossing) that is disposed between the die 21 and die
pad 22 and the punch 23.
[0081]
The sheet thickness of the blank 24 is preferably 0.6 to 2.8 mm, more
preferably 0.8 to 2.8 mm, and further preferably 1.0 to 2.8 mm.
[0082]
The press component 11 or the intermediate component 11-1 has a hat-shaped
cross-sectional shape. The hat-shaped cross-sectional shape is a shape that includes a
top plate lla, two convex ridge lines lib, lib, two vertical walls lie, 11c, two concave
ridge lines 11 d, 11 d, and two flanges 11 e, 11 e.
[0083]
The press component 11 or the intermediate component 11-1 thereof has a
curved portion 13. The curved portion 13 curves so that the external shape of the top
plate 11 a in a plan view orthogonal to the top plate 11 a is an inverted L-shaped.
[0084]
The top plate lla extends in a first direction (arrow direction in Figures 2 and
17). The two convex ridge lines 11 b, 11 b connect to both end portions in a direction
which is orthogonal (that is, the width direction of the top plate 11 a) to the first direction
of the top plate 11a. The two vertical walls 11c, llc connect to the two convex ridge
lines llb, llb, respectively. The two concave ridge lines 11d, 11d connect to the two
vertical walls 11c, 11c, respectively. The two flanges lle, lle connect to the two
concave ridge lines 11 d, II d, respectively.
[0085]
The manufacturing apparatus 20 is favorably used in the following first case
and second case.
First case: A case satisfying one or more conditions among a condition that the blank 24
is made from an ultra-high tensile strength steel sheet having a tensile strength of 1180
MPa or more, a condition that a projection distance in a product height direction of the
vertical wall llc as a height of the press component 11 or the intermediate component
24
11-1 thereof is 70 mm or more, a condition that a radius of curvature R, of the concave
ridge line 11 d of the press component 11 or the intermediate component 11-1 thereof is
10 mm or less in side view, and a condition that a radius of curvature R2 on an inner
circumferential side of the curved portion 13 of the press component 11 or the
intermediate component 11-1 thereof is 100 mm or less in plan view.
Second case: A case satisfying at least two conditions among a condition that the blank
24 is made from an ultra-high tensile strength steel sheet having a tensile strength of
1180 MPa or more, a condition that a height (projection distance in a product height
direction of the vertical wall 11 c) of the press component 11 or the intermediate
component 11-1 thereof is 55 mm or more, a condition that a radius of curvature R, of
the concave ridge line 11 d of the press component 11 or the intermediate component
11-1 thereof is 15 mm or less in side view, and a condition that a radius of curvature R2
on an inner side of the curved portion 13 of the press component 11 or the intermediate
component 11-1 thereof is 140 mm or less in plan view.
[0086]
This is because, if press working by the conventional free bending method is
perfmmed on the blank 24 in the first case or the second case, cracks will be generated
in the flange 11 e on the inner circumferential side of the curved portion 13 of the
obtained press component 11 or intermediate component 11-1 thereof, and therefore the
significance of using the manufacturing apparatus 20 will be recognized.
[0087]
The die pad 22 presses a portion of the blank 24 to be formed into a part of the
top plate 11 a at the curved portion 13 of the press component 11 with an applied
pressure that is 1.0 MPa or more and less than 32.0 MPa, or comes adjacent to or into
contact with the aforementioned portion of the blank 24 while maintaining the distance
of a gap with respect to the punch 23 at a distance corresponding to 1.0 to 1.1 times the
sheet thickness of the blank 24.
[0088]
By this means, while out-of-plane deformation at the aforementioned portion
of the blank 24 is being suppressed by the die pad 22, the intermediate component 11-1
25
of the press component 11 is manufactured by performing press working that 1s
described hereunder.
[0089]
That is, in the press working, in a state in which a portion of the blank 24 to be
formed into the end portion 11 fin the first direction of the top plate 11 a is present on the
same plane as a portion of the blank 24 to be formed into the top plate 11 a, the die 21
and the punch 23 are relatively moved in directions in which the die 21 and the punch
23 approach each other.
[0090]
By this means, the vertical wall 11c, the concave ridge line 11d and the flange
11 e on the inner circumferential side of the curved portion 13 are formed while the
portion of the blank 24 to be formed into the end portion 11 f is caused to move in-plane
(slide) over a portion of the die 22 at which the top plate 11a will be formed.
[0091]
In this way, the intermediate component 11-1 of the press component 11 is
manufactured.
[0092]
Figure 3 is an explanatory drawing illustrating the positional relationship
between a material inflow facilitating portion forming mechanism 25 and a concave
ridge line forming portion 23b of the manufacturing apparatus 20, and the blank 24.
[0093]
In addition to performing press working by bending forming using the free
bending method disclosed by Patent Documents 1 and 2 and the like, in the
manufacturing apparatus 20, as illustrated in Figures 1 and 3, a recess 21a and a
protrusion 23a as the material inflow facilitating portion forming mechanism 25 for
providing a material inflow facilitating portion 19 in the blank 24 are provided in the die
21 and the punch 23, respectively, of the manufacturing apparatus 20. The material
inflow facilitating portion forming mechanism 25 is constituted by the recess 21 a that is
provided in the die 21 and the protrusion 23a that is provided in the punch 23.
[0094]
26
At the time of performing the press working, as illustrated in Figure 2, the
manufacturing apparatus 20 uses the material inflow facilitating portion forming
mechanism 25 to provide the material inflow facilitating portion 19 in the vicinity (for
example, at only the flange, or at the flange and the concave ridge line) of a portion of
the blank 24 to be formed into the flange 11e on the inner circumferential side of the
curved portion 13 of the intermediate component 11-1.
(0095]
As illustrated in Figures 2 and 3, preferably the material inflow facilitating
portion forming mechanism 25 provides the material inflow facilitating portion 19 in a
region that is outside a region (hatched region in Figure 3) of the blank 24 to be formed
into the press component 11. By this means, by cutting off the outer edge of the flange
11 e of the intermediate component 11-1 as a trim line, it is possible not to leave a trace
of the material inflow facilitating portion 19 in the press component 11.
[0096]
In a case where it is acceptable for a trace of the material inflow facilitating
portion 19 to remain in the press component 11, the material inflow facilitating portion
19 may be provided in a region of the blank 24 (hatched region in Figure 3) to be
formed into the press component 11.
[0097]
Next, the material inflow facilitating portion forming mechanism 25 will be
described in more detail.
[0098]
Figure 4 is an explanatory drawing illustrating a cross-section in a conventional
punch 23-1 in which the material inflow facilitating portion forming mechanism 25 is
not provided, that corresponds to a cross-section A-A in Figure 1.
[0099]
Figure 5 is an explanatory drawing illustrating the positional relationship
between the blank 24 and the material inflow facilitating portion forming mechanism 25
and concave ridge line forming portion 23b of the manufacturing apparatus 20, and
locations of cross-sections B, C and D.
27
[0100]
Figure 6 is a graph illustrating cross-section line length differences (inflow
amounts) with respect to a conventional punch at a flange forming portion of the punch
23 at the cross-sections B, C and D. In the cross-sections B, C and D in the graph in
Figure 6, the left side illustrates a case according to the conventional method, and the
right side illustrates a case according to the method of the present invention. Further,
the cross-sections below the graph in Figure 6 illustrate the respective shapes of the
blank 24 at the cross-sections B, C and D.
[0101]
Figure 7 is an explanatory drawing illustrating a cross-section A-A of the punch
23 in which the material inflow facilitating portion forming mechanism 25 is provided.
[0102]
In the aforementioned first case or second case, if press working of the blank
24 is performed by the free bending method using the conventional punch 23-1,
cracking will occur at a portion "a" shown in Figure 4.
[0103]
As illustrated in Figures 5 and 6, according to the present invention, by
providing the material inflow facilitating portion forming mechanism 25 that is
constituted by the recess 21a and the protrusion 23a, the material inflow facilitating
portion 19 is provided in the intermediate component 11-1 by press working.
[0104]
The cross-sections B, C and D in Figures 5 and 6 are cross-sections in a
material inflow direction that is parallel to a straight line that is tangent to a center
position (portion "a") of an inner circumference of the curved portion 13 in a plan view
orthogonal to the top plate lla. The cross-sections B, C and D are cross-sections in a
maximum principal strain direction of a deformation of a portion to be formed into the
flange lle on the inner circumferential side of the curved portion 13.
The material inflow facilitating portion 19 is provided so that cross-section line
lengths at the cross-sections B, C and D gradually increase with distance from the
flange lle on the inner circumferential side of the curved portion 13.
28
[0105]
The cross-sectional shape of the material inflow facilitating portion 19 is not
limited to a shape which monotonously increases with distance from the flange lie on
the inner circumferential side of the curved portion 13 of the intermediate component
11-1, and may be a shape that partially includes a. portion at which the cross-section line
length is constant.
[0106]
That is, as illustrated in Figure 6, in comparison to the conventional method in
which the material inflow facilitating portion forming mechanism 25 is not provided,
the material inflow facilitating portion forming mechanism 25 of the method of the
present invention is provided so that a cross-section line length difference (inflow
amount) relative to the conventional punch of the flange forming portion of the punch
23 increases at each of the cross-sections B, C and D, and so that the cross-section line
length difference (inflow amount) at the cross-section C increases more than the
cross-section line length difference (inflow amount) at the cross-section B, and the
cross-section line length difference (inflow amount) at the cross-section D increases
more than the cross-section line length difference (inflow amount) at the cross-section
C.
[0107]
In other words, in the present invention, the material inflow facilitating portion
forming mechanism 25 having a shape that increases the cross-section line length
difference (inflow amount) at each of the cross-sections B, C and D is provided in the
die 21 as the recess 21a and is also provided in the punch 23 as the protrusion 23a.
[0108]
For example, as illustrated in Figure 7, the material inflow facilitating portion
19 is exemplified as being provided as a protrusion having an external shape that is
obtained by connecting the meeting point of the concave ridge line 11 d and the flange
11 e of the curved portion 13 that is formed, and an end portion 24a of the blank 24 at
the time that forming starts.
[0109]
29
Figure 8 is an explanatory drawing illustrating the positional relationship
between the blank 24 and the material inflow facilitating portion forming mechanism 25
and concave ridge line forming portion 23b of the manufacturing apparatus 20, and the
locations of cross-sections B, C and D.
[0110]
As described above, a change differential in the inflow amount of the material
that is caused by the material inflow facilitating portion forming mechanism 25
increases with distance from the portion "a" of the blank 24 through the cross-section B,
the cross-section C and furthermore the cross-section D as indicated by a broad arrow in
Figure 8.
[0111]
Note that, cracking at the portion "a" of the blank 24 shown in Figure 4 occurs
when a tensile force in the circumferential direction that is not less than the
rupture-yield strength of the blank 24 locally arises. Therefore, if a change in the
cross-section line length difference is imparted to the portion "a", cracking at the portion
"a" will be more liable to occur. Accordingly, practically no change may be provided
in the cross-section line length difference at the portion "a". Further, it is sufficient to
set a region that provides a change in the cross-section line length difference (inflow
amount) as a region up to the position at which the blank 24 is present before forming,
that is, up to the end portion 24a illustrated in Figure 7.
[0112]
Next, the function of the material inflow facilitating portion forming
mechanism 25 will be described.
[0113]
Figure 9 is an explanatory drawing that shows the reason why cracking at the
portion "a" of the blank 24 is prevented by providing the material inflow facilitating
portion forming mechanism 25 that is constituted by the recess 21 a and the protrusion
23a, in the die 21 and the punch 23.
[0114]
Cracking at the portion "a" of the blank 24 is attributable to a high tensile force
30
F in the circumferential direction of the concave ridge line 11 d that is located at an
upper part of the portion "a" in the blank 23. In the present invention, by providing the
material inflow facilitating portion forming mechanism 25 in the die 21 and the punch
23 and performing press working, the inflow amount of the blank 24 to an outer side
relative to the portion "a" is increased.
[0115]
By this means, because the inflow amount of the blank 24 increases from
around the portion "a", the inflow amount of the blank 24 to the portion "a" increases.
That is, the inflow amount of the blank 24 to the portion of the blank 24 to be formed
into the curved portion 13 is increased by means of the material inflow facilitating
portion forming mechanism 25. Although the direction of principal strain of a
deformation in the portion of the blank 24 to be formed into curved portion 13 does not
change significantly, the amount of deformation thereof is reduced.
[0116]
Thus, according to the present invention, as illustrated by arrows in Figure 9,
the inflow amount of the blank 24 to a portion of the blank 24 to be formed into the
flange 11 e on the inner circumferential side of the curved portion 13 of the press
component 11 increases in comparison to the conventional method in which the material
inflow facilitating portion forming mechanism 25 is not provided.
[0117]
By this means, in the blank 24, since the tensile force F in the circumferential
direction of the concave ridge line lld that is located at the upper part of the portion "a"
can be reduced and the deformation load at the portion of the blank 24 to be formed into
the curved portion 13 can be decreased, cracking is prevented at the portion "a" of the
blank 24.
[0118]
Figure 10(a) to Figure 10(f) are explanatory drawings that partially illustrate
examples of the shape of the protrusion 23a or a recess 23c that are constituent elements
of various kinds of the material inflow facilitating portion forming mechanism 25 that is
provided in the punch 23.
31
[0119]
As illustrated in Figure 1 O(a), a protrusion that is convex toward the same side
as the top plate 11 a of the press component 11 that was described above referring to
Figure 7 can be used as the protrusion 23a that is a constituent element of the material
inflow facilitating portion forming mechanism 25 provided in the punch 23.
[0120]
As illustrated in Figure 1 O(b ), the recess 23c that is convex toward the opposite
side to the top plate 11 a of the press component 11 may be used instead of the
protrusion 23a illustrated in Figure IO(a). In this case, it need scarcely be said that a
protrusion corresponding to the recess 23c is provided in the die 21.
[0121]
As illustrated in Figure 1 0( c), in a case where the blank 24 is small, the
protrusion 23a may be provided in a region which is in contact with the blank 24.
[0122]
As described in the foregoing and as is also illustrated in Figure 1 0( d), in a case
where it is acceptable for a trace of the material inflow facilitating portion 19 to remain
in the press component 11, the protrusion 23a as the material inflow facilitating portion
19 may be provided so as to extend over a region (hatched region in Figure 3) of the
blank 24 to be formed into the press component 11.
[0123]
As illustrated in Figure lO(e), two or more of the protrusions 23a that are
independent may be provided as constituent elements of the material inflow facilitating
portion forming mechanism 25.
[0124]
In addition, as illustrated in Figure 1 O(f), the protrusion 23a may be provided in
a stepped shape in a direction parallel to the sheet thickness direction of the blank 12.
[0125]
Thus, the material inflow facilitating portion forming mechanism 25 provides
one or more of the material inflow ~acilitating portions 19 that increase an inflow
amount by which a portion of the blank 24 to be formed into the end portion 11 f of the
32
intermediate component 11-1 flows into a portion of the blank 24 to be formed into the
flange 11 e on the inner circumferential side of the curved portion 13 of the intermediate
component 11-1.
[0126]
Figure ll(a) and Figure ll(b) are explanatory drawings that respectively
illustrate intermediate components 11-2 and 11-3 of other press components to be
manufactured by the present invention.
[0127]
In the above description, a case of manufacturing the intermediate component
11-1 having the shape illustrated in Figure 2 by means of the present invention was
taken as an example. However, the present invention is not limited to the case
described above and is also applicable to a case of manufacturing the intermediate
component 11-2 illustrated in Figure 11(a) and a case of manufacturing the intermediate
component 11-3 illustrated in Figure 11 (b), that is, the intermediate components 11-2
and 11-3 that have one of the convex ridge line 11 b, the vertical wall 11 c, the concave
ridge line 11d and the flange 11e, respectively.
[0128]
2. Manufacturing method of the present invention
In the manufacturing method of the present invention, basically the
intermediate component 11-1 of the press component 11 is manufactured by the free
bending method using the manufacturing apparatus 20.
[0129]
The press component 11 that is taken as the manufacturing object of the present
invention preferably satisfies the aforementioned first case or second case. This is
because, in the press component 11 that satisfies the first case or second case, cracking
occurs at the portion "a" of the blank 24 when manufactured by the conventional free
bending method.
[0130]
That is, a portion (hatched portion 18a in Figure 20) of the blank 24 to be
formed into a part of the top plate 11 a of the curved portion 13 of the press component
33
11 is pressed with an applied pressure that is 1.0 MPa or more and less than 32.0 MPa
by the die pad 22, or while maintaining the distance of a gap between the die pad 22 and
the punch 23 at a distance corresponding to 1.0 to 1.1 times the sheet thickness of the
blank 24, the die pad 22 is brought adjacent to or into contact with the portion (hatched
portion 18a in Figure 20) to be formed into the top plate lla of the curved portion 13 of
the press component 11.
[0131]
By this means, while suppressing out-of-plane deformation of the portion to be
formed into a part of the top plate 11 a, the intermediate component 11-1 of the press
component 11 is manufactured by performing press working that is described hereunder.
[0132]
That is, in the press working, in a state in which a portion of the blank 24 to be
formed into the end portion 11 fin the first direction of the top plate 11 a is present on the
same plane as a portion of the blank 24 to be formed into the top plate 11 a, the die 21
and the punch 23 are relatively moved in directions in which the die 21 and the punch
23 approach each other.
[0133]
By this means, the vertical wall llc, the concave ridge line lld and the flange
lle on the inner circumferential side of the curved portion 13 are formed while the
portion of the blank 24 to be formed into the end portion 11 f is caused to move in-plane
(slide) over a portion of the die 21 at which the top plate lla will be formed.
[0134]
By this press working, the material inflow facilitating portion forming
mechanism 25 provided in the die 21 and the punch 23 provides at least one material
inflow facilitating portion 19 in the vicinity of the portion of the blank 24 to be formed
into the flange 11 e on the inner circumferential side of the curved portion 13 of the
intermediate component 11-1.
[0135]
According to the present invention, as described in the for~going referring to
Figure 9, an inflow amount of the blank 24 to a portion of the blank 24 to be formed
34
into the flange 11 e on the inner circumferential side of the curved portion 13 of the
intermediate component 11-1 increases. Therefore, in the blank 24, the tensile force F
in the circumferential direction of the concave ridge line 11 d that is located at an
upperpart of the portion "a" can be reduced, and by this means cracking at the portion
"a" ofthe blank 24 is prevented.
[0136]
In a case where there is no unwanted part in the intermediate component 11-1
that underwent press working according to the free bending method by means of the
manufacturing apparatus 20, the intermediate component 11-1 serves as it is as the press
component 11 that is the end product. On the other hand, in a case where there is an
unwanted part in the intermediate component 11-1, the intermediate component 11-1 is
made into the press component 11 by cutting off (trimming) the unwanted part including
the material inflow facilitating portion 19 by taking the outer edge portion of the flange
11 e as a trim line.
EXAMPLE 1
[0137]
With respect to each of the intermediate component 11-1 (example
embodiment of the present invention) illustrated in Figure 2 manufactured using the
manufacturing apparatus 20 illustrated in Figure 1, and a press component (comparative
example) manufactured using a manufacturing apparatus 14 illustrated in Figure 20, a
maximum sheet thickness reduction ratio at a meeting point "a" portion between the
concave ridge line 11 d and the flange 11 e at a center position in the circumferential
direction of the curved portion 13 was analyzed by the finite element method using a
computer.
[0138]
The specifications of the intermediate component 11-1 and the press
component that were analyzed are as described hereunder:
• Tensile strength and sheet thickness of blanks 24 and 18: 1180 MPa or more, and 1.6
mm
35
• Height (projection distance in product height direction of vertical wall llc) of
intermediate component 11-1 and press component: 60 mm
• Radius of curvature R1 of concave ridge line 11 d of intermediate component 11-1 and
press component: 20 mm in side view
• Radius of curvature R2 on inner side of curVed portion 13 of intermediate component
11-1 and press component: 100 mm in plan view
According to this analysis, if the maximum sheet thickness reduction ratio
calculated by the dynamic explicit method using the finite element method was 8% or
less, it was determined that there was no cracking at the aforementioned meeting point,
while if the maximum sheet thickness reduction ratio that was similarly calculated was
more than 13% it was determined that there was cracking at the aforementioned meeting
point.
[0139]
As a result, it was found that the maximum sheet thickness reduction ratio at
the aforementioned meeting point "a" portion of the intermediate component 11-1
(example embodiment of the present invention) was 8% and it thus was determined that
there was no cracking at the meeting point "a" portion, while in contrast it was found
that the maximum sheet thickness reduction ratio at the meeting point "a" portion of the
press component (comparative example) was 13% and it was thus determined that there
was cracking at the meeting point "a" portion.
[0140]
According to the present invention, even when press working by the free
bending method is performed on the blank 24 in the aforementioned first case or second
case, the L-shaped component 11-1 can be manufactured without generating cracking in
the flange 11 e on the inner circumferential side of the curved portion 13.

claims.
We claim:
[Claim 1]
A method for manufacturing a press component, by performing press working
on a blank or a pre-formed blank disposed between a die and a die pad, and a punch that
is disposed facing the die and die pad, which constitute a press-forming apparatus that
employs bending forming,
the press component having a cross-sectional shape constituted by a top plate
extending in a first direction, a convex ridge line connecting to an end portion of the top
plate in a direction orthogonal to the first direction, a vertical wall connecting to the
convex ridge line, a concave ridge line connecting to the vertical wall, and a flange
connecting to the concave ridge line, and also having a curved portion that, with the
convex ridge line, the vertical wall and the concave ridge line curving, provides an
external shape of the top plate with an L-shape, a T -shape or a Y -shape in a plan view
that is orthogonal to the top plate,
the method comprising, when manufacturing the press component:
weakly pressing a portion of the blank to be formed into a part of the top plate
of the curved portion by the die pad, or subjecting the die pad to approach or come in
contact with a portion of the blank to be formed into a part of the top plate of the curved
portion while maintaining a gap between the die pad and the punch at a distance that is
not less than a sheet thickness of the blank and not more than 1.1 times the sheet
thickness of the blank, and
forming, in a state in which a portion of the blank to be formed into an end
portion of the top plate in the first direction is present on a same plane as the portion of
the blank to be formed into the top· plate, the vertical wall, the concave ridge line and
the flange on an inner circumferential side of the curved portion while causing the
portion of the blank that is to be formed into the end portion of the top plate in the first
direction to move in-plane over a portion of the die at which the top plate will be
formed by relatively moving the die and the punch in directions in which the die and the
punch approach each other,
wherein,
42
by the press working, in a vicinity of a portion of the blank to be formed into a
flange on the inner circumferential side of the curved portion of the press component,
one or more material inflow facilitating portions are provided, the material inflow
facilitating portions increasing an inflow amount by which the portion of the blank to be
formed into the end portion flows into the portion of the blank to be formed into the
flange on the inner circumferential side of the curved portion, and
the material inflow facilitating portion includes, in a plan view orthogonal to
the top plate, a cross-sectional shape in which a cross-section line length in a
cross-section parallel to a straight line that is tangent to a middle position of an inner
circumference of the curved portion increases with distance from the flange on the inner
circumferential side of the curved portion.
[Claim 2]
The method for manufacturing a press component according to claim 1,
wherein the method satisfies at least one of the following conditions:
the blank comprises an ultra-high tensile strength steel sheet having a tensile
strength of 1180 MPa or more;
a projection distance of the vertical wall in a product height direction as a
height of the press component is 70 mm or more;
a radius of curvature of the concave ridge line of the press component is 10
mm or less in side view; and
a radius of curvature on the inner circumferential side of the curved portion in
the press component is 100 mm or less in the plan view.
[Claim 3]
The method for manufacturing a press component according to claim 1,
wherein the method satisfies two or more of the following conditions:
the blank comprises an ultra-high tensile strength steel sheet having a tensile
strength of 1180 MPa or more;
a projection distance of the vertical wall in a product height direction as a
height of the press component is 55 mm or more;
a radius of curvature of the concave ridge line of the press component is 15
43
mm or less in side view, and
a radius of curvature on an inner side of the curved portion in the press
component is 140 mm or less in the plan view.
[Claim 4]
The method for manufacturing a press component according to any one of
claims 1 to 3, wherein:
in the blank, the material inflow facilitating .portion is provided at a region that
is outside of a region to be formed into the press component.
[Claim 5]
The method for manufacturing a press component according to any one of
claims 1 to 4, wherein:
the cross-sectional shape includes a case where the cross-section line length is
partially constant.
[Claim 6]
The method for manufacturing a press component according to any one of
claims 1 to 5, wherein:
the material inflow facilitating portion is a convex bead that is convex toward a
same side as the top plate of the press component, or is a concave bead that is convex
toward an opposite side to the top plate of the press component.
[Claim 7]
The method for manufacturing a press component according to any one of
claims 1 to 6, wherein:
the material inflow facilitating portion is provided at least in a region in which
the blank is present.
[Claim 8]
The method for manufacturing a press component according to any one of
claims 1 to 7, wherein:
the material inflow facilitating portion is provided in a stepped shape in a
direction parallel to a sheet thickness direction of the blank.
[Claim 9]
44
The method for manufacturing a press component according to any one of
claims 1 to 8, wherein:
the material inflow facilitating portion has an external shape obtained by
connecting a meeting point of the concave ridge line and the flange in the curved
portion that is formed, and an end portion of the blank at a time when the forming starts.
[Claim 10]
The method for manufacturing a press component according to any one of
claims 1 to 9, wherein:
the cross-sectional shape is a hat-shaped cross-sectional shape constituted by:
a top plate extending in a first direction,
two convex ridge lines connecting to both end portions of the top plate
in a direction orthogonal to the first direction,
two vertical walls com1ecting to the two convex ridge lines,
respectively,
two concave ridge lines connecting to the two vertical walls,
respectively, and
two flanges connecting to the two concave ridge lines, respectively.
(Claim 11]
An apparatus for manufacturing a press component, that comprises a die and a
die pad, and a punch that is disposed facing the die and die pad, and that:
by performing press working on a blank or a pre-formed blank that is disposed
between the die and die pad and the punch,
manufactures a press component having a cross-sectional shape constituted by
a top plate extending in a first direction, a convex ridge line connecting to an end
portion in a direction orthogonal to the first direction of the top plate, a vertical wall
connecting to the convex ridge line, a concave ridge line connecting to the vertical wall,
and a flange connecting to the concave ridge line, and also having a curved portion that,
with the convex ridge line, the vertical wall and the concave ridge line curving, provides
an external shape of the top plate with an L-shape, T -shape or Y -shape in a plan view
that is orthogonal to the top plate,
45
the apparatus manufacturing the press component by:
the die pad weakly pressing a portion of the blank to be formed into a part of
the top plate of the curved portion, or the die pad approaching or contacting with a
portion of the blank to be formed into a part of the top plate of the curved portion while
maintaining a gap between the die pad and the punch at a distance that is not less than a
sheet thickness of the blank and not more than 1.1 times the sheet thickness of the blank,
and
in a state in which a portion of the blank to be formed into an end portion in the
first direction of the top plate is present on a same plane as the portion of the blank to be
formed into the top plate, by the die and the punch moving relatively in directions in
which the die and the punch approach each other, forming the vertical wall, the concave
ridge line and the flange on an inner circumferential side of the curved portion while
causing the portion of the blank to be formed into the end portion to move in-plane over
a portion of the die at which the top plate will be formed;
wherein:
the die and the punch comprise a material inflow facilitating portion forming
mechanism that, by means of the press working, in a vicinity of a portion of the blank to
be formed into a flange on an inner circumferential side of the curved portion of the
press component, provides one or more material inflow facilitating portions that
increase an amount by which a portion of the blank to be formed into the end portion
flows into the portion of the blank to be formed into the flange on the inner
circumferential side of the curved portion; and
the material inflow facilitating portion forming mechanism provides the
material inflow facilitating portion in a manner so that, in a plan view that is orthogonal
to the top plate, a cross-section line length of the material inflow facilitating pmtion at a
cross-section that is parallel to a straight line that is tangent to a center position of an
inner circumference of the curved portion increases with distance from the flange on the
inner circumferential side of the curved portion.
[Claim 12]
The apparatus for manufacturing a press component according to claim 11,
46
wherein the apparatus satisfies at least one of the following conditions:
the blank comprises an ultra-high tensile strength steel sheet having a tensile
strength of 1180 MPa or more;
a projection distance of the vertical wall in a product height direction as a
height of the press component is 70 nun or more;
a radius of curvature of the concave ridge line of the press component is 10
nun or less in side view; and
a radius of curvature on the inner circumferential side of the curved portion in
the press component is 1 00 nun or less in the plan view.
[Claim 13]
The apparatus for manufacturing a press component according to claim 11,
wherein the apparatus satisfies two or more of the following conditions:
the blank comprises an ultra-high tensile strength steel sheet having a tensile
strength of 1180 MPa or more;
a projection distance of the vertical wall in a product height direction as a
height of the press component is 55 nun or more;
a radius of curvature of the concave ridge line of the press component is 15
mm or less in side view, and
a radius of curvature on an inner side of the curved portion in the press
component is 140 nun or less in the plan view.
[Claim 14]
The apparatus for manufacturing a press component according to any one of
claims 11 to 13, wherein:
the material inflow facilitating portion forming mechanism provides the
material inflow facilitating portion at a region of the blank that is outside of a region to
be formed into the press component.
[Claim 15]
The apparatus for manufacturing a press component according to any one of
claims 11 to 14, wherein:
the cross-sectional shape includes a case where the cross-section line length is
47
partially constant.
[Claim 16]
The apparatus for manufacturing a press component according to any one of
claims 11 to 15, wherein:
the material inflow facilitating portion is a convex bead that is convex toward a
same side as the top plate of the press component, or is a concave bead that is convex
toward an opposite side to the top plate of the press component.
[Claim 17]
The apparatus for manufacturing a press component according to any one of
claims 11 to 16, wherein:
the material inflow facilitating portion forming mechanism provides the
material inflow facilitating portion in at least a region in which the blank is present.
[Claim 18]
The apparatus for manufacturing a press component according to any one of
claims 11 to 17, wherein:
the material inflow facilitating portion forming mechanism provides the
material inflow facilitating portion in a stepped shape in a direction parallel to a sheet
thickness direction of the blank.
[Claim 19]
The apparatus for manufacturing a press component according to any one of
claims 11 to 18, wherein:
the material inflow facilitating portion forming mechanism provides the
material inflow facilitating portion so as to have an external shape obtained by
connecting a region of the blank to be formed into a meeting point between the concave
ridge line and the flange of the curved portion, and an end portion of the blank prior to
the forming.
[Claim 20]
The apparatus for manufacturing a press component according to any one of
claims 11 to 19, wherein:
the cross-sectional shape 1s a hat-shaped cross-sectional shape
48
constituted by:
a top plate extending in a first direction,
two convex ridge lines connecting to both end portions of the top plate
in a direction orthogonal to the first direction,
two vertical walls connecting to the two convex ridge lines,
respectively,
two concave ridge lines connecting to the two vertical walls,
respectively, and
two flanges connecting to the two concave ridge lines, respectively.