U.S. patent application number 13/719764 was filed with the patent office on 2013-08-22 for press product forming method.
This patent application is currently assigned to TOPRE CORPORATION. The applicant listed for this patent is TOPRE CORPORATION. Invention is credited to KENICHI OGASAWARA.
Application Number | 20130213109 13/719764 |
Document ID | / |
Family ID | 48981231 |
Filed Date | 2013-08-22 |
United States Patent
Application |
20130213109 |
Kind Code |
A1 |
OGASAWARA; KENICHI |
August 22, 2013 |
PRESS PRODUCT FORMING METHOD
Abstract
Provided is a press product forming method for press-forming a
curved press product. The curved press product is formed into a
hat-like cross-section including an upper surface portion, side
wall portions, and flange portions. The press product forming
method includes: a pre-forming step of forming, at a widthwise end
portion of a flat plate-like blank, at least one bending portion
extending along a longitudinal direction; and a main forming step
of forming the upper surface portion and the side wall portions
under a state in which the bending portion is left.
Inventors: |
OGASAWARA; KENICHI;
(KANAGAWA, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOPRE CORPORATION; |
|
|
US |
|
|
Assignee: |
TOPRE CORPORATION
TOKYO
JP
|
Family ID: |
48981231 |
Appl. No.: |
13/719764 |
Filed: |
December 19, 2012 |
Current U.S.
Class: |
72/379.2 |
Current CPC
Class: |
B21D 11/20 20130101;
B21D 22/02 20130101 |
Class at
Publication: |
72/379.2 |
International
Class: |
B21D 11/20 20060101
B21D011/20 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 2012 |
JP |
2012-035781 |
Claims
1. A press product forming method for press-forming a curved press
product, the curved press product being formed into a hat-like
cross-section including: an upper surface portion; side wall
portions each bending and extending from a widthwise edge of the
upper surface portion in a direction crossing the upper surface
portion; and flange portions each bending and extending from an
edge of each of the side wall portions, the widthwise edge of the
upper surface portion being shaped so as to curve and extend along
a longitudinal direction, the press product forming method
comprising: a pre-forming step of forming, at a widthwise end
portion of a flat plate-like blank, a highly rigid portion
extending along the longitudinal direction; and a main forming step
of forming the upper surface portion and the side wall portions
under a state in which the highly rigid portion is left.
2. A press product forming method according to claim 1, wherein the
main forming step is carried out by hot press forming.
3. A press product forming method according to claim 1, further
comprising a flange-portion flattening step of pressing and
flattening the highly rigid portion into one of the flange
portions.
4. A press product forming method according to claim 3, wherein the
main forming step is carried out by hot press forming.
5. A press product forming method according to claim 1, wherein the
highly rigid portion comprises at least one of: a ridge which
protrudes to at least one of a front surface side and a back
surface side of the flat plate-like blank; and a bending portion
which is formed through bending the widthwise end portion of the
flat plate-like blank obliquely to at least one of the front
surface side and the back surface side of the flat plate-like
blank.
6. A press product forming method according to claim 5, wherein the
main forming step is carried out by hot press forming.
7. A press product forming method according to claim 5, further
comprising a flange-portion flattening step of pressing and
flattening the highly rigid portion into one of the flange
portions.
8. A press product forming method according to claim 7, wherein the
main forming step is carried out by hot press forming.
9. A press product forming method comprising: providing a
substantially flat plate-like blank; pre-forming the blank to
create at least one bending portion at or near a widthwise end
portion of the blank, the at least one bending portion extending
along a longitudinal direction of the blank; forming the pre-formed
blank into a curved press comprising a hat-like cross-section
including: an upper surface portion; side wall portions each
bending and extending from a widthwise edge of the upper surface
portion at an angle from the upper surface portion; and flange
portions each bending and extending from an edge of each of the
side wall portions, the widthwise edge of the upper surface portion
curving and extending along the longitudinal direction, wherein the
step of forming the pre-formed blank into the curved press is such
that the upper surface portion and the side wall portions are
formed while the at least one bending portion remains intact.
10. The method of claim 9, wherein the step of forming the
pre-formed blank into the curved press comprises hot press
forming.
11. The method of claim 9, further comprising pressing and
flattening the at least one bending portion into one of the flange
portions.
12. The method of claim 11, wherein the step of forming the
pre-formed blank into the curved press comprises hot press
forming.
13. The method of claim 9, wherein the at least one bending portion
comprises at least one of: a ridge which protrudes from at least
one of a front surface side and a back surface side of the flat
plate-like blank; and a bent flange formed by bending the widthwise
end portion of the flat plate-like blank obliquely relative to at
least one of the front surface side and the back surface side of
the flat plate-like blank.
14. The method of claim 13, wherein the step of forming the
pre-formed blank into the curved press comprises hot press
forming.
15. The method of claim 13, further comprising pressing and
flattening the at least one bending portion into one of the flange
portions.
16. The method of claim 13, wherein the ridge is triangular in
cross-section.
17. The method of claim 9, wherein the step of pre-forming the
blank comprises creating at least two bending portions, with a
first bending portion extending along the longitudinal direction of
the blank at a first widthwise end portion of the blank and the a
second bending portion extending along the longitudinal direction
of the blank at a second widthwise end portion of the blank.
18. The method of claim 13, wherein the bent flange extends from
the at least one of the front surface side and the back surface
side at an angle between approximately 10.degree. and approximately
90.degree..
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority from Japanese Patent
Application No. 2012-035781 filed on Feb. 22, 2012, the entirety of
which is hereby incorporated by reference into this
application.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This disclosure relates to a press product forming
method.
[0004] 2. Description of the Related Art
[0005] There is known a technology of press-forming a press
product, with Japanese Patent Application Laid-open No. 2010-36217
disclosing one example.
[0006] However, in a case where the press product is a curved press
product which exhibits a curved shape in plan view or in side view,
an excess material resulting from the curved shape is more likely
to cause forming defects, such as wrinkles, in the flange
portions.
[0007] FIG. 1 is a perspective view of a mold for forming a curved
press product according to the related art. As illustrated in FIG.
2, in a curved press product 101 according to the related art, a
bending portion is not formed at a widthwise end portion of a
blank. Accordingly, the widthwise end portion of the blank has low
rigidity, and hence has low resistance against a force of shrinking
the blank in a longitudinal direction. Therefore, as illustrated in
FIG. 3, the excess material resulting from the curved shape is more
likely to cause wrinkles, with the result that a large number of
wrinkles 140 occur in flange portions 107. Note that, when upper
forming sections 31 of the mold are further lowered under the state
illustrated in FIG. 2, layers of wrinkles occur when the flange
portions 107 are formed by lower surfaces 31b of the upper forming
sections 31 and upper surfaces 36a of flange-portion forming
sections 36 of the mold.
SUMMARY OF THE INVENTION
[0008] According to an exemplary embodiment of this disclosure,
there is provided a press product forming method for press-forming
a curved press product, the curved press product being formed into
a hat-like cross-section including: an upper surface portion; side
wall portions each bending and extending from a widthwise edge of
the upper surface portion in a direction crossing the upper surface
portion; and flange portions each bending and extending from an
edge of each of the side wall portions, the widthwise edge of the
upper surface portion being shaped so as to curve and extend along
a longitudinal direction. In some embodiments, the press product
forming method includes: a pre-forming step of forming, at a
widthwise end portion of a flat plate-like blank, a highly rigid
portion extending along the longitudinal direction; and a main
forming step of forming the upper surface portion and the side wall
portions under a state in which the highly rigid portion is
left.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] In the accompanying drawings:
[0010] FIG. 1 is a perspective view of a mold for forming a curved
press product according to the related art;
[0011] FIG. 2 is a cross-sectional view taken along the line A-A of
FIG. 1, for illustrating a forming state in the midst of a main
forming step according to the related art;
[0012] FIG. 3 is a perspective view of the curved press product in
the midst of the main forming step according to the related
art;
[0013] FIG. 4A is a perspective view of a curved press product
according to a first embodiment of this disclosure;
[0014] FIG. 4B is a cross-sectional view of the curved press
product taken along the line B-B of FIG. 4A;
[0015] FIG. 5A is a perspective view of a blank according to the
first embodiment of this disclosure after completion of a
pre-forming step;
[0016] FIG. 5B is a cross-sectional view of the blank taken along
the line C-C of FIG. 5A;
[0017] FIG. 6 is a perspective view of a mold for forming a curved
press product according to an example of this disclosure;
[0018] FIG. 7 is a cross-sectional view taken along the line D-D of
FIG. 6, for illustrating a forming state in the midst of a main
forming step according to the example of this disclosure;
[0019] FIG. 8 is a perspective view of the curved press product
according to the example of this disclosure in the midst of the
main forming step;
[0020] FIG. 9 is a cross-sectional view taken along the line D-D of
FIG. 6, for illustrating a state after completion of a
flange-portion flattening step;
[0021] FIG. 10A is a perspective view of a curved press product
according to a second embodiment of this disclosure;
[0022] FIG. 10B is a cross-sectional view of the curved press
product taken along the line E-E of FIG. 10A;
[0023] FIG. 11A is a perspective view of a blank according to the
second embodiment of this disclosure after completion of the
pre-forming step;
[0024] FIG. 11B is a cross-sectional view of the blank taken along
the line F-F of FIG. 11A;
[0025] FIG. 12A is a perspective view of a curved press product
according to a third embodiment of this disclosure;
[0026] FIG. 12B is a cross-sectional view of the curved press
product taken along the line G-G of FIG. 12A;
[0027] FIG. 13A is a perspective view of a blank according to the
third embodiment of this disclosure after completion of the
pre-forming step;
[0028] FIG. 13B is a cross-sectional view of the blank taken along
the line H-H of FIG. 13A;
[0029] FIG. 14A is a perspective view of a curved press product
according to a fourth embodiment of this disclosure;
[0030] FIG. 14B is a cross-sectional view of the curved press
product taken along the line I-I of FIG. 14A;
[0031] FIG. 15A is a perspective view of a blank according to the
fourth embodiment of this disclosure after completion of the
pre-forming step;
[0032] FIG. 15B is a cross-sectional view of the blank taken along
the line J-J of FIG. 15A;
[0033] FIG. 16A is a perspective view of a blank according to
another embodiment of this disclosure;
[0034] FIG. 16B is a cross-sectional view of the blank taken along
the line K-K of FIG. 16A;
[0035] FIG. 17A is a perspective view of a blank according to the
another embodiment of this disclosure after completion of the
pre-forming step;
[0036] FIG. 17B is a cross-sectional view of the blank taken along
the line L-L of FIG. 17A;
[0037] FIG. 18A is a perspective view of a curved press product
according to the another embodiment of this disclosure after
completion of the flange-portion flattening step; and
[0038] FIG. 18B is a cross-sectional view of the curved press
product taken along the line M-M of FIG. 18A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0039] In the following, embodiments of this disclosure are
described with reference to the drawings. Note that, in each
drawing, W represents a width direction, L represents a
longitudinal direction, UPR represents an upper side, and LWR
represents a lower side. Further, a drawing viewed from the width
direction W illustrates a side view, a drawing viewed from the
upper side UPR or the lower side LWR illustrates a plan view, and a
drawing viewed from the longitudinal direction L illustrates a
front view.
First Embodiment
[0040] As illustrated in FIGS. 4A and 4B, a curved press product 1
according to a first embodiment of this disclosure is formed into a
hat-like cross-section including: an upper surface portion 3
arranged on the upper side of the curved press product so as to
extend in the longitudinal direction L; a pair of right and left
side wall portions 5 each extending from a widthwise edge 3a of the
upper surface portion 3 obliquely downward (in a direction crossing
the upper surface portion 3) ; and flange portions 7 bending and
extending respectively from lower ends 5a (edges) of the side wall
portions 5 to both right and left sides.
[0041] The widthwise edge 3a of the upper surface portion 3 is
formed into a convex shape that bulges to the upper side UPR along
the longitudinal direction L in side view.
[0042] A press product forming method according to this embodiment
includes a pre-forming step, a main forming step, and a
flange-portion flattening step.
[0043] As illustrated in FIGS. 5A and 5B, the pre-forming step is
carried out in such a manner that a highly rigid portion 9
extending along the longitudinal direction L is formed at each
widthwise end portion of a flat plate-like blank (not shown).
Specifically, as in a case of a blank 2, the highly rigid portion 9
includes a bending portion 11 which is formed through bending a
widthwise end portion of the blank 2 obliquely to the upper side
UPR (front surface side). In some cases, the bending portion 11 and
a body portion 13 form an angle .theta. of, for example,
approximately 10.degree. to approximately 90.degree.. Further, in
some embodiments, the bending portion 11 is formed into a
substantially straight shape in order to prevent occurrence of
wrinkles at the time of pre-forming. Note that, after the
pre-forming step and before the main forming step, the blank 2 may
be heated.
[0044] The main forming step is carried out in such a manner that
the upper surface portion 3 and the side wall portions 5 are formed
in the heated blank 2 using a mold which is described in detail
later.
[0045] The flange-portion flattening step is carried out in such a
manner that the bending portion 11 of the highly rigid portion 9
formed in the pre-forming step is pressed and flattened into the
flange portion using the above-mentioned mold. As described above,
the main forming step and the flange-portion flattening step may be
carried out by hot press forming under a state in which the blank 2
is heated.
[0046] After the flange-portion flattening step is finished, the
blank is quenched. In this manner, the curved press product 1 that
is increased in strength is completed as illustrated in FIG.
4A.
EXAMPLE
[0047] Next, procedures for forming the curved press product
according to the first embodiment using the mold are described in
detail.
[0048] As illustrated in FIG. 6, a mold 21 includes an upper die 23
and a lower die 25. The upper die 23 includes a mounting plate 27
and an upper forming die 29 provided under the mounting plate 27.
The upper forming die 29 is formed into a U-shape in front view,
and includes a pair of right and left upper forming sections 31
extending downward, and a coupling section 32 bridging the upper
forming sections 31. Further, the lower die 25 includes a mounting
plate 33 and a lower forming die 35 provided on the mounting plate
33. The lower forming die 35 is formed into a T-shape in front
view, and includes flange-portion forming sections 36 provided on
right and left sides thereof, and a lower forming section 37 formed
through protruding upward a center portion thereof in a right-left
direction. The lower forming section 37 is fitted between the pair
of upper forming sections 31. Further, upper surfaces 36a of the
flange-portion forming sections 36 and an upper surface 37a of the
lower forming section 37 are formed so as to exhibit a convex shape
that bulges to the upper side UPR in side view. Note that, as shown
in FIG. 7, lower surfaces 31b of the upper forming sections 31 and
a lower surface 32b of the coupling section 32 are curved so as to
conform to the upper surfaces 36a and the upper surface 37a of the
lower forming die 35. As described above, the mold 21 according to
this embodiment is formed of a simply-structured mold (forming
mold) which is not provided with a wrinkle prevention device (blank
holder) or the like.
[0049] As illustrated in FIG. 7, in the main forming step, the
upper surface portion 3 is formed in the heated blank in such a
manner that a widthwise center portion of the blank is brought into
contact with the upper surface of the lower forming section 37, and
each side wall portion 5 is formed in the heated blank in such a
manner that each widthwise side region of the blank is sandwiched
between a side surface 37b of the lower forming section 37 and an
inner side surface 31a of the upper forming section 31. Here, the
bending portion 11 is formed at each widthwise end portion of the
blank along the longitudinal direction. Accordingly, the widthwise
end portion of the blank 2 has high rigidity, and thus has high
resistance against a force of shrinking the blank in the
longitudinal direction. Therefore, an excess material resulting
from a curved shape is less likely to cause wrinkles. As a result,
as illustrated in FIG. 8, wrinkles 40 are less likely to occur in
the flange portion 7. Note that, when the upper forming sections 31
are further lowered under the state illustrated in FIG. 7, as
illustrated in FIG. 9, in the flange-portion flattening step, each
bending portion 11 is pressed by the lower surface 31b of the upper
forming section 31 and the upper surface 36a of the flange-portion
forming section 36. In this manner, the flat flange portion 7 has
less wrinkles and no layers of wrinkles.
[0050] In the following, operations and effects of this embodiment
are described.
[0051] (1) According to this embodiment, provided is a press
product forming method for press-forming the curved press product
1. The curved press product 1 is formed into a hat-like
cross-section including: the upper surface portion 3; the side wall
portions 5 each bending and extending from the widthwise edge 3a of
the upper surface portion 3 in a direction crossing the upper
surface portion 3; and the flange portions 7 each bending and
extending from the edge 5a of each of the side wall portions 5. The
widthwise edge 3a of the upper surface portion 3 is shaped so as to
curve and extend along the longitudinal direction L.
[0052] Further, the press product forming method includes: the
pre-forming step of forming, at the widthwise end portion of the
flat plate-like blank, each bending portion 11 (highly rigid
portion 9) extending along the longitudinal direction; and the main
forming step of forming the upper surface portion 3 and the side
wall portions 5 under a state in which each highly rigid portion 9
is left.
[0053] As described above, in the press product forming method
according to this embodiment, the upper surface portion 3 and the
side wall portions 5 are formed under the state in which each
bending portion 11 extending along the longitudinal direction is
left. Accordingly, each widthwise end portion of the blank 2 is
increased in rigidity, and is increased in resistance against the
force of shrinking the blank in the longitudinal direction.
Therefore, at the time of forming the upper surface portion 3 and
the side wall portions 5, even when the excess material resulting
from the curved shape causes action of the force of shrinking the
blank in the longitudinal direction, it is possible to prevent or
minimize the occurrence of forming defects, such as wrinkles and
layers of wrinkles, in the flange portions 7.
[0054] (2) Each highly rigid portion 9 includes the bending portion
11 formed through bending the widthwise end portion of the blank 2
obliquely to the front surface side, and hence it is possible to
increase rigidity of the widthwise end portion of the blank 2.
[0055] (3) The press product forming method according to this
embodiment further includes the flange-portion flattening step of
pressing and flattening the bending portions 11 (highly rigid
portions 9) into the flange portions 7 as illustrated in FIG. 9.
Accordingly, it is possible to prevent occurrence of wrinkles in
the flange portions 7, and to form the flat flange portions 7. In
other embodiments, the flange-portion flattening step is not
necessary.
[0056] (4) The main forming step and the flange-portion flattening
step may be carried out by hot press forming. This further
increases the significance of forming the bending portion 11 at
each widthwise end portion of the blank 2 so as to increase
rigidity of the widthwise end portion. That is, in a case of cold
press forming, the blank itself has higher rigidity than in a case
of hot press forming. Accordingly, in the case of application of
the force of shrinking the blank in the longitudinal direction, or
at the time of forming the flange portions, wrinkles and layers of
wrinkles are less likely to occur in the flange portions 7. On the
other hand, in the case of hot press forming, the blank itself has
lower rigidity than in the case of cold press forming. Accordingly,
in the case of application of the force of shrinking the blank in
the longitudinal direction, or at the time of forming the flange
portions, wrinkles and layers of wrinkles are more likely to occur
in the flange portions 7. Therefore, the bending portion 11 is
formed at the widthwise end portion of the blank 2 to thereby
increase rigidity of the widthwise end portion. In this manner, it
is possible to effectively prevent occurrence of wrinkles and
layers of wrinkles.
Second Embodiment
[0057] Next, a second embodiment of this disclosure is described.
The same components as those of the first embodiment are denoted by
the same reference symbols, and description thereof is omitted.
[0058] In the curved press product 1 according to the first
embodiment, the widthwise edge 3a of the upper surface portion 3 is
formed into a convex shape that bulges to the upper side UPR along
the longitudinal direction L in side view.
[0059] However, as illustrated in FIG. 10A, in a curved press
product 51 according to the second embodiment, an inner curved
widthwise edge 53a and an outer curved widthwise edge 53b of an
upper surface portion 53 are each formed into an arc shape that
curves along the longitudinal direction L in plan view. Note that a
cross-sectional shape illustrated in FIG. 10B is the same as that
of the first embodiment illustrated in FIG. 4B, and the curved
press product 51 is formed into a hat-like cross-section including
the upper surface portion 53, side wall portions 55, and flange
portions 57. Further, of the flange portions 57, an inner curved
flange portion is denoted by 57a, and an outer curved flange
portion is denoted by 57b.
[0060] Similarly to the first embodiment, a press product forming
method according to this embodiment includes a pre-forming step, a
main forming step, and a flange-portion flattening step.
[0061] As illustrated in FIGS. 11A and 11B, the pre-forming step is
carried out in such a manner that a highly rigid portion 9A
extending along the longitudinal direction is formed at one of
widthwise end portions of a flat plate-like blank (not shown).
Specifically, as in a case of a blank 52, the highly rigid portion
9A includes a bending portion 58 which is formed through bending a
left widthwise end portion of the blank 52 obliquely to the upper
side (front surface side). In some cases, the bending portion 58
and a body portion 59 form an angle .theta. of, for example,
approximately 10.degree. to approximately 90.degree.. Further, the
bending portion 58 is provided in an outer curved region of the
curved press product 51 in plan view. Still further, the bending
portion 58 may be formed into a straight shape in order to prevent
occurrence of wrinkles at the time of the pre-forming step.
[0062] The main forming step and the flange-portion flattening step
are the same as those of the first embodiment. Note that, similarly
to the above-mentioned first embodiment, the main forming step and
the flange-portion flattening step may be carried out by hot press
forming under a state in which the blank is heated.
Operations and Effects of this Embodiment are the same as those of
the First Embodiment
[0063] In particular, rigidity of the widthwise end portion is
increased in such a manner that the bending portion 58 is formed at
the widthwise end portion corresponding to the outer curved flange
portion 57b in which wrinkles are more likely to occur. Thus, it is
possible to effectively prevent occurrence of wrinkles and layers
of wrinkles in the outer curved flange portion 57b.
Third Embodiment
[0064] Next, a third embodiment of this disclosure is described.
The same components as those of the first and second embodiments
are denoted by the same reference symbols, and description thereof
is omitted.
[0065] As illustrated in FIGS. 12A and 12B, a curved press product
61 according to the third embodiment has the same shape as that of
the curved press product 1 according to the first embodiment. That
is, the curved press product 61 is formed into a hat-like
cross-section including an upper surface portion 3, side wall
portions 5, and flange portions 7. Further, a widthwise edge 3a of
the upper surface portion 3 is formed into a convex shape that
bulges to the upper side UPR along the longitudinal direction L in
side view.
[0066] Similarly to the first and second embodiments, a press
product forming method according to this embodiment includes a
pre-forming step, a main forming step, and a flange-portion
flattening step.
[0067] As illustrated in FIGS. 13A and 13B, the pre-forming step is
carried out in such a manner that triangular ridges 63 (ridges)
functioning as highly rigid portions 9B and extending along the
longitudinal direction are formed respectively at both widthwise
end portions of a flat plate-like blank (not shown). Specifically,
as in a case of a blank 62, both the widthwise end portions of the
flat plate-like blank are protruded to the upper side (front
surface side), to thereby form the ridges 63 each having a dogleg
cross-section protruding upward. Further, in some cases, each of
the ridges 63 is formed into a straight shape in order to prevent
occurrence of wrinkles at the time of the pre-forming step.
[0068] The main forming step and the flange-portion flattening step
are the same as those of the first and second embodiments. Note
that, similarly to the above-mentioned first and second
embodiments, the main forming step and the flange-portion
flattening step may be carried out by hot press forming under a
state in which the blank is heated.
Operations and Effects of this Embodiment are the same as those of
the First and Second Embodiments
[0069] In particular, the triangular ridges 63 are formed
respectively at the widthwise end portions of the blank 62, and
thus rigidity of the widthwise end portions is increased.
Accordingly, the highly rigid portions 9B can effectively prevent
occurrence of wrinkles and layers of wrinkles in the flange
portions 7.
Fourth Embodiment
[0070] Next, a fourth embodiment of this disclosure is described.
The same components as those of the first to third embodiments are
denoted by the same reference symbols, and description thereof is
omitted.
[0071] A curved press product 71 according to the fourth embodiment
has the same shape as that of the curved press product 51 according
to the second embodiment. That is, as illustrated in FIGS. 14A and
14B, the curved press product 71 is formed into a hat-like
cross-section including an upper surface portion 53, side wall
portions 55, and flange portions 57. Further, of the flange
portions 57, an inner curved flange portion is denoted by 57a, and
an outer curved flange portion is denoted by 57b. An inner curved
widthwise edge 53a and an outer curved widthwise edge 53b of the
upper surface portion 53 are each formed into an arc shape that
curves along the longitudinal direction L in plan view.
[0072] Similarly to the first to third embodiments, a press product
forming method according to this embodiment includes a pre-forming
step, a main forming step, and a flange-portion flattening
step.
[0073] As illustrated in FIGS. 15A and 15B, the pre-forming step is
carried out in such a manner that a triangular ridge 73 (ridge)
functioning as a highly rigid portion 9C and extending along the
longitudinal direction L is formed at one of widthwise end portions
of a flat plate-like blank (not shown). Specifically, as in a case
of a blank 72, one of the widthwise end portions of the flat
plate-like blank is protruded to the upper side (front surface
side), to thereby form the ridge 73 having a dogleg cross-section
protruding to the upper side UPR. Further, the triangular ridge 73
is provided in an outer curved region of the curved press product
71 in plan view. Still further, in some cases, the ridge 73 is
formed into a straight shape in order to prevent occurrence of
wrinkles at the time of the pre-forming step.
[0074] The main forming step and the flange-portion flattening step
are the same as those of the first to third embodiments. Note that,
similarly to the above-mentioned first to third embodiments, the
main forming step and the flange-portion flattening step may be
carried out by hot press forming under a state in which the blank
is heated.
Operations and Effects of this Embodiment are the same as those of
the First to Third Embodiments
[0075] In particular, the triangular ridge 73 is formed at the
widthwise end portion of the blank 72, and thus rigidity of the
widthwise end portion is increased. Accordingly, the highly rigid
portion 9C can effectively prevent occurrence of wrinkles and
layers of wrinkles in the outer curved flange portion 57b.
Other Embodiment
[0076] Next, forming steps according to another embodiment of this
disclosure are described step by step. Here, a case of forming a
center pillar is described by way of example.
[0077] First, a flat plate-like blank 90 is formed of a flat steel
plate extending in an elongated manner as illustrated in FIGS. 16A
and 16B, and includes a longitudinal center portion 93 having a
relatively large width.
[0078] Next, in a pre-forming step, a bending portion 95 (highly
rigid portion 9D shown in FIG. 17A) is formed in such a manner that
each widthwise end portion of the longitudinal center portion 93 of
the flat plate-like blank 90 is bent obliquely to the upper side
(front surface side). Thus, the blank 90 is formed into a blank 91
illustrated in FIGS. 17A and 17B.
[0079] Then, as illustrated in FIGS. 18A and 18B, after an upper
surface portion 96 and side wall portions 97 are formed in the
heated blank 91 in a main forming step under a state in which the
bending portions 95 are left, the bending portions 95 are pressed
and flattened into flange portions 98 in a flange-portion
flattening step. The blank 91 is then quenched so as to be
increased in strength. Thus, a center pillar 99 according to this
embodiment is completed. Note that, similarly to the
above-mentioned first to fourth embodiments, the main forming step
and the flange-portion flattening step may be carried out by hot
press forming under a state in which the blank is heated.
[0080] As described above, according to this embodiment, even in a
case where the highly rigid portions 9D are formed in a part of the
longitudinal portion of the blank 91, it is possible to effectively
prevent occurrence of wrinkles and layers of wrinkles in the flange
portions 98.
[0081] The first to fourth embodiments and another embodiment of
this disclosure are described above, but this disclosure is not
limited thereto. Various modifications and changes can be made
thereto.
[0082] For example, in the first to fourth embodiments and another
embodiment, the bending portion is extended obliquely to the upper
side (front surface side), but may be extended to the lower side
(back surface side).
[0083] Further, regarding the ridge, a shape other than the
triangular ridge is also applicable. However, in order to prevent a
layered portion from being formed in a ridge when pressing the
ridge in the flange-portion flattening step, a ridge having a ridge
line, such as the triangular ridge, is preferred.
[0084] In addition, in the above-mentioned embodiments, the highly
rigid portions 9 to 9C are pressed and flattened, but the highly
rigid portions 9 to 9C may be left unpressed and unflattened in the
obtained products.
[0085] Further, the press forming according to this disclosure may
include cold press forming which does not require heating of a
blank and quenching performed after forming.
* * * * *