DESCRIPTION
TITLE OF INVENTION: PRESS-WORK METHOD AND BOTTOMED
CONTAINER
TECHNICAL FIELD
[0001] The present invention relates to a press-work
method of thickening an inclined portion rising from
a bottom surface portion of a bottomed container, and
to a bottomed container manufactured by the same.
BACKGROUND ART
[0002] With reference to Fig. 1A and Fig. IB, as a
method of thickening a vertical wall of a bottomed
container, a method in which a disk-shaped workpiece
is formed into a bottomed container 11 by deep
drawing, and an end surface lib of the bottomed
container is pushed by a pushing punch 14 while a
bottomed container bottom surface 11a is sandwiched
by a die 12 and a pressing punch 13, to thereby
thicken a vertical wall lie of the bottomed container
has been conventionally in general use. In this
method, however, being constrained only weakly, the
vertical wall portion of the bottomed container
buckles during the thickening, so that folding lid
occurs. This has made it difficult to realize a
large thickening ratio (sheet thickness after the
thickening/original sheet thickness) exceeding 1.3.
For example, Patent Literature 1 discloses a
thickening press-work method in which a pressing
punch and an upsetting punch are provided, and
between an upper end portion and a bottom inner
- 1 -
portion of a workpiece, a gap is reserved between the
pressing punch and a die, and an upper surface of the
end portion of the workpiece is pressed by the
upsetting punch. However, in the method of Patent
Literature 1, folding may also occur because buckling
occurs in the gap during the thickening.
[0003] Therefore, there has been proposed a method
to overcome the drawbacks of the above-described
thickening methods, in the manufacture of a pulley'
piston for continuously variable transmission of an
automobile, as described in Non Patent Literature 1,
This forming method is capable of preventing folding
ascribable to buckling because a portion to be
thickened is thickened by pushing an end portion of a
cup in a state where a constraint surface of a
material is increased by providing a corner portion
in the portion to be thickened. However, since a gap
of the portion to be thickened is geometrically
decided by constraint by the shape of a mold and the
movement of the mold, a maximum thickening ratio that
can be achieved in one forming is about 1.5. Further,
before this process, it is necessary to form a
bottomed cylindrical container by deep drawing or the
like, and totally two processes are required.
[0004] Further, Patent Literature 2 proposes a
method in which a press-worked workpiece which has an
end wall, a bent portion bent from an outer periphery
of the end wall toward one side, and a cylindrical
portion provided to continue from the bent portion is
~ 2 -
used, the workpiece is clamped by a crank punch
adapted to an inner surface of the workpiece, a clamp
die adapted to an outer surface of the end wall, and
a thickness-increase guide die fitted to an outer
peripheral surface of the clamp die so as to be
swingable in an axial direction and adapted to outer
peripheral surfaces of the bent portion and the
cylindrical portion, a thickness-increasing punch is
inserted in space formed between the clamp punch and
the thickness-increase guide die to apply an axialdirection
compression load to the cylindrical portion,
thereby thickening the bent portion, and the
thickness-increase guide die is retracted from the
clamp die according to the thickening.
Further, Patent Literature 3 proposes a structure
in which a knockout for receiving a body portion of a
workpiece, a plate presser for pressing an area up to
the middle of a rising portion rising obliquely
outward from the body portion, a thickness-increasing
punch for pressing a tip of the rising portion, and a
die for receiving the rising portion are provided,
and the die is movable in an axial direction
relatively to the knockout and the thicknessincreasing
punch. In the process of crushing the
rising portion by pressing the tip of the rising
portion by the thickness-increasing punch, the die is
pressed by the rising portion which is in the course
of being thickened without being pushed by the
thickness-increasing punch, to move relatively to the
„ 3 _
knockout, so that a gap between the plate presser and
the die which sandwich the rising portion widens.
However, the methods of Patent Literatures 2 f 3
also require the forming of a bottomed cylindrical
container by deep drawing or the like, and thus
require totally two processes. Further, a cutting
process is sometimes required because a large step
occurs in a boundary between a thickened portion and
a non-thickened portion. Further, an achievable
thickening ratio is not mentioned.
Further, in the structure in which the die is
divided and part thereof is moved, in Patent
Literature 2, for example, a force in a direction
perpendicular to an inclined portion (2b in Patent
Literature 2) acts on the thickness-increase guide
die at the time of the thickening. Since this force
acts in such a direction as to make the thicknessincrease
guide die separate from the clamp die
(outward in a diameter direction), a gap occurs in a
boundary between the clamp die and the thicknessincrease
guide die, which may cause a burr.
CITATION LIST
PATENT LITERATURE
[000 5] Patent Literature 1: Japanese Laid-open
Patent Publication No. 2001-47175
Patent Literature 2: Japanese Laid-open Patent
Publication No. 2010-247199
Patent Literature 3: Japanese Laid-open Patent
Publication No. 2009-248092
- 4 -
NON-PATENT LITERATURE
[0006] Non Patent Literature 1: "Automotive
Engineering", Automotive Engineers of Japan Inc.,
1996, Vol. 50, No 12, p.31-37
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0007] The present invention was made in order to
solve the above-described conventional drawbacks and
its main object is to make it possible to avoid
folding due to buckling to achieve thickening with a
thickening ratio of 1.5 times or more in a press-work
Its another object is to make it possible to
manufacture a bottomed container having a smooth
shape without a large step in a boundary between a
thickened portion and a non-thickened portion. Its
another object is to make it possible to manufacture
a bottomed container whose inclined portion is
thickened, from a disk-shaped workpiece by a presswork
having one process.
SOLUTION TO PROBLEM
[0008] The gist of the present invention that is to
achieve the aforesaid obj ects is as follows.
[1] A press-work method using a press mold, which
includes an inner punch, an intermediate punch
disposed along an outer periphery of the inner punch
and having an intermediate punch inclined portion at
a leading end, an outer punch disposed along an outer
periphery of the intermediate punch, and a die having
a die inclined portion facing the intermediate punch
- 5 -
inclined portion, central axes of all of which are
disposed coaxially, the method including a thickening
step of, while constraining a bottom portion of a
bottomed container by the inner punch and the die,
pressing an end portion of the bottomed container by
the outer punch and moving the intermediate punch in
a direction opposite a direction in which the outer
punch is pressed, to thereby thicken a bottomed
container inclined portion of the bottomed container
sandwiched by the intermediate punch inclined portion
and the die inclined portion.
[2] A press-work method using a press mold which
includes an inner punch having an inner punch flat
portion and an inner punch inclined portion at a
leading end, an intermediate punch disposed along an
outer periphery of the inner punch and having an
intermediate punch inclined portion at a leading end,
an outer punch disposed along an outer periphery of
the intermediate punch, and a die having a die
inclined portion disposed to face the intermediate
punch inclined portion, central axes of all of which
are disposed coaxially, the inner punch inclined
portion being formed at an end portion, of the.
leading end of the inner punch, on a side adjacent to
the intermediate punch inclined portion, the method
including:
an outer punch pressing step of, while
constraining a bottom portion of a bottomed container
by the inner punch flat portion and the die, pressing
- 6 -
an end portion of the bottomed container by the outer
punch to thereby bring a bottomed container inclined
portion, of the bottomed container, which extends
along the inner punch inclined portion and the
intermediate punch inclined portion, into contact
with the die inclined portion;
an intermediate punch pressing step of pressing
the intermediate punch in a direction of the die
against the bottomed container which is brought into
contact with the die inclined portion in the outer
punch pressing step, to bring the intermediate punch
inclined portion into contact with the bottomed
container inclined portion; and
a thickening step of pressing the outer punch
against the bottomed container which is brought into
contact with the intermediate punch inclined portion
in the intermediate punch pressing step, and moving
the intermediate punch in a direction opposite a
direction in which the outer punch is pressed, to
thereby thicken the bottomed container inclined
portion.
[3] The press-work method according to [1],
including, before the thickening step, a forming step
of pressing a disk-shaped workpiece into the die by
the inner punch and the intermediate punch to form
the bottomed container in which the bottomed
container inclined portion is formed at a position
sandwiched by the intermediate punch inclined portion
and the die inclined portion.
- 7
[4] The press-work method according to [2],
including, before the outer punch pressing step, a
forming step of pressing a disk-shaped workpiece into
the die by the inner punch and the intermediate punch
to form the bottomed container in which the bottomed
container inclined portion is formed at a position
sandwiched by the inner punch inclined portion and
the intermediate punch inclined portion, and the die
inclined portion.
[5] The bottomed container manufactured by the
press-work method according to [1], wherein a
thickening ratio of a thickness of the bottomed
container inclined portion is 1.5 times or more.
[6] The bottomed container manufactured by the
press-work method according to [2] , wherein a
thickening ratio of a thickness of the bottomed
container inclined portion is 1,5 times or more.
ADVANTAGEOUS EFFECTS OF INVENTION
[000 9] According to the present invention, it is
possible to avoid folding due to buckling to achieve
thickening with a thickening ratio of 1.5 times or
more .
Further, according to the invention according to
claim 2, it is possible to manufacture a bottomed
container having a smooth shape without a large step
in a boundary between a thickened portion and a nonthickened
port ion.
Furthermore, according to the inventions
according to claims 3, 4, it is possible to
manufacture a bottomed container whose inclined
portion is thickened, from a disk-shaped workpiece by
a press-work having one process.:
BRIEF DESCRIPTION OF DRAWINGS
[0010] [Fig. 1A] Fig. 1A is a cross-sectional view
illustrating a conventional thickening work.
[Fig. IB] FIG. IB is a cross-sectional view
illustrating the conventional thickening work.
[Fig. 2] Fig. 2 is a cross-sectional view
illustrating a state before deep drawing in a presswork
method according to a first embodiment.
[Fig. 3] Fig. 3 is a cross-sectional view
illustrating a state after the deep drawing in the
press-work method according to the first embodiment.
[Fig. 4 ] Fig. 4 is a cross-sectional view
illustrating a state in the middle of thickening in
the press-work method according to the first
embodiment.
[Fig. 5] Fig. 5 is a cross-sectional view
illustrating a state after the thickening in the
press-work method according to the first embodiment.
[Fig. 6] Fig. 6 is a cross-sectional view
illustrating a state before deep drawing in a presswork
method according to a second embodiment.
[Fig. 7] Fig. 7 is a cross-sectional view
illustrating a state after the deep drawing in the
press-work method according to the second embodiment.
[Fig. 8] Fig. 8 is a cross-sectional view
illustrating a state where an inclined portion of a
- 9 -
die is brought into contact with an inclined portion
of a bottomed container in the press-work method
according to the second embodiment.
[Fig. 9] Fig. 9 is a cross-sectional view
illustrating a state where an inclined portion of an
intermediate punch is brought into contact with the
inclined portion of the bottomed container in the
press-work method according to the second embodiment.
[Fig. 10] Fig. 10 is a cross-sectional view
illustrating a state in the middle of thickening in
the press-work method according to the second
embodiment.
[Fig. 11] Fig. 11 is a cross-sectional view
illustrating a state after the thickening in the
press-work method according to the second embodiment.
[Fig. 12] Fig. 12 is a cross-sectional view
illustrating a comparative example of the second
embodiment.
DESCRIPTION OF EMBODIMENTS
[0011] Hereinafter, modes for carrying out the
present invention will be described with reference to
the attached drawings.
As a result of studious studies, the present
inventor has found out that, by performing deep
drawing by using an inner punch, an intermediate
punch disposed along an outer periphery of the inner
punch, and a die, central axes of all of which are
coaxially disposed, to form a bottomed container, and
subsequently, while constraining a workpiece,
- 10 -
performing thickening by gradually increasing a gap
between the intermediate punch and the die when an
end surface of the bottomed container is pressed by
the outer punch, it is possible to perform the
thickening with a thickening ratio of 1.5 times or
more by a press-work having one process while
avoiding folding due to buckling.
[0012] (First Embodiment)
Fig. 2 is a cross-sectional view illustrating a
state before deep drawing is executed. As
illustrated in Fig. 2 , a press mold includes an inner
punch 23, an intermediate punch 2 4 disposed along an
outer periphery of the inner punch 23, an outer punch
2 5 disposed along an outer periphery of the
intermediate punch 24, a knockout 26, and a die 27
disposed along an outer periphery of the knockout 26,
central axes of all of which are coaxially disposed.
The inner punch 2 3 is disposed to face the knockout
26 and the die 27, and the intermediate punch 24 and
the outer punch 25 are disposed to face the die 27.
[0013] The inner punch 23 has a columnar shape, and
is of a movable type capable of moving up and down by
a not-illustrated drive source of a mechanical type
(hydraulic or servo motor, or the like).
The intermediate punch 2 4 has a cylindrical shape,
and on its surface that comes into contact with a
portion to be thickened of a workpiece (that is, on a
lower end portion (leading end) of the intermediate
punch 24), an intermediate punch inclined portion 24a
- 11 -
is formed. This intermediate punch inclined portion
2 4a is inclined in an obliquely upward direction from
an inner punch 23 side toward an outer punch 25 side.
The intermediate punch 24 is of a movable type
capable of moving up and down by a not-illustrated
mechanical drive source.
The outer punch 25 has a cylindrical shape and is
of a movable type capable of moving up and down, by a
not-illustrated mechanical drive source,
[0014] The knockout 26 has a columnar shape, is
intended to detach a formed product from the mold,
and is of a movable type capable of moving up and
down by a not-illustrated mechanical drive source.
The die 27 is of a fixed type, has a
substantially concave shape, and has, at a center
portion, a hole allowing the knockout 26 to be
inserted therein. Further, in the die 27, a die
inclined portion 2 7a is formed, and this die inclined
portion 27a is disposed to face the intermediate
punch inclined portion 24a.
[0015] In this embodiment, by executing the
following forming step and thickening step, the
workpiece 21 was press-worked. As the workpiece 21,
a disk-shaped high-tensile steel sheet (SAPH5 90)
having a 240 mm outside diameter and a 4 mm sheet
thickness was used.
[0016] The workpiece 21 is placed on the die 27 and
is subjected to the deep drawing by pressing the
inner punch 23 and the intermediate punch 24, whereby
- 12 -
a bottomed container 22 in which a bottomed container
inclined portion 22a is formed at a position
sandwiched by the intermediate punch inclined portion
24a and the die inclined portion 27a is formed as
illustrated in Fig. 3 (forming step).
[0017] In the state illustrated in Fig. 3, a bottom
portion of.the bottomed container 22 is constrained
by the inner punch 23 and the die 27.
Subsequently, as illustrated in Fig. 4 and Fig. 5,
an end surface of the bottomed container 2 2 formed in
the forming step is pressed by the outer punch 25,
and the intermediate punch 24 is moved upward.
Consequently, a gap between the intermediate punch
inclined portion 2 4a and the die inclined portion 2 7a
gradually becomes larger, which makes it possible to
perform the thickening while suppressing buckling by
sandwiching the bottomed container inclined portion
22a by the intermediate punch inclined portion 24a
and the die inclined portion 2 7a (thickening step).
The cross-sectional views in Fig. 4 and Fig. 5
illustrate states in the middle of the thickening and
after the thickening respectively.
[0018] After the thickening step, the inner punch 23,
the intermediate punch 24, the outer punch 25, and
the knockout 2 6 are moved upward, and the bottomed
container 22 is detached from the die 27, A sheet
thickness of the bottomed container inclined portion
2 2a is 6.9 mm, and thus the thickness can be
increased to 1.73 times an original sheet thickness
- 13
of 4 mm without any occurrence of folding due to
buckling.
Further, at the time of the thickening, a force
in a direction perpendicular to the intermediate
punch inclined portion 2 4a acts on the intermediate
punch 24, but since this force acts in such a
direction as.to press the intermediate punch 2 4
against the inner punch 23 (inward in a diameter
direction (center direction)}, there occurs no gap in
a boundary between the inner punch 23 and the
intermediate punch 24 and a burr is not generated.
[0019] (Second Embodiment)
In a second embodiment, a bottomed container
having a smooth shape without a large step in a
boundary between a thickened portion and a nonthickened
portion is manufactured.
Fig. 6 is a cross-sectional view illustrating a
state before deep drawing is executed. As
illustrated in Fig. 6, a press mold includes an inner
punch 33, an intermediate punch 3 4 disposed along an
outer periphery of the inner punch 33, an outer punch
35 disposed along an outer periphery of the
intermediate punch 34, a knockout 36, and a die 37
disposed along an outer periphery of the knockout 36,
central axes 30 of all of which are coaxially
disposed. The inner punch 33 is disposed to face the
knockout 36 and the die 37, and the intermediate
punch 34 and the outer punch 35 are disposed to face
the die 37.
- 14 -
[0020] The inner punch 33 has a columnar shape, and
on its leading end, an inner punch inclined portion
33a and an inner punch flat portion 33b are formed.
The inner punch inclined portion 3 3a is formed on a
peripheral edge portion of the leading end, that is,
on an end portion on a side adjacent to an
intermediate punch inclined portion 34a, and the
inner punch flat portion 33b is formed around the
central axis 30. The inner punch inclined portion
33a is inclined in an obliquely upward direction from
a central axis 30 side toward an intermediate punch
34 side. The inner punch flat portion 33b extends in
a horizontal direction perpendicular to the central
axis 30. The inner punch 33 is of a movable type
capable of moving up and down by a not-illustrated
mechanical drive source.
[0021] The intermediate punch 34 has a cylindrical
shape, and on its surface that comes into contact
with a portion to be thickened of a workpiece (that
is, on a lower end portion (leading end) of the
intermediate punch 34}, the intermediate punch
inclined portion 3 4a is formed. This intermediate
punch inclined portion 3 4a is inclined in an
obliquely upward direction from an inner punch 33
side toward an outer punch 35 side. The intermediate
punch 34 is of a movable type capable of moving up
and down by a not-illustrated mechanical drive source.
Here, when a height of an end portion of the
inner punch inclined portion 3 3a on a side more
- 15 -
distant from the central axis 30 and a height of an
end portion of the intermediate punch inclined
portion 34a on a side closer to the central axis 30
are equal, that is, in the state illustrate in Fig. 6,
the inner punch inclined portion 33a and the
intermediate punch inclined portion 34a form a smooth
curve.
[0022] The outer punch 35 has a cylindrical shape
and is of a movable type capable of moving up and
down by a not-illustrated mechanical drive source.
[0023] The knockout 36 has a columnar shape, is
intended to detach a formed product from the mold,
and is of a movable type capable of moving up and
down by a not-illustrated mechanical drive source.
The die 37 is of a fixed type, has a
substantially concave shape, and has, at a center
portion, a hole allowing the knockout 36 to be
inserted therein. In the die 37, a die inclined
portion 37a is formed, and this die inclined portion
37a is disposed to face the inner punch inclined
portion 33a and the intermediate punch inclined
portion 34a.
[0024] In this embodiment, by executing the
following forming step, outer punch pressing step,
intermediate punch pressing step, and thickening step,
the workpiece 31 was press-worked. As the workpiece
31, a disk-shaped high-tensile steel sheet {SAPH5 90)
having a 224 outside diameter and a 4 mm sheet
thickness was used.
16 -
[0025] The workpiece 31 is placed on the die 37, and
is subjected to the deep drawing by pressing the
inner punch 3 3 and the intermediate punch 34, whereby
a bottomed container 32 in which a bottomed container
inclined portion 32a is formed at a position
sandwiched by the inner punch inclined portion 33a
and the intermediate punch inclined portion 34a, and
the die inclined portion 37a is formed as illustrated
in Fig. 7 (forming step).
[0026] In the state illustrated in Fig, 1, a bottom
portion of the bottomed container 32 is constrained
by the inner punch flat portion 3 3b of the inner
punch 33 and the die 37.
Subsequently, an end surface of the bottomed
container 32 formed in the forming step is pressed by
the outer punch 35, whereby the bottomed container
inclined portion 32a extending along the inner punch
inclined portion 3 3a and the intermediate punch
inclined portion 34a is brought into contact with the
die inclined portion 37a as illustrated in Fig. 8
(outer punch pressing step).
[002 7] Subsequently, the intermediate punch 34 is
moved downward toward the bottomed container 32 which
is brought into contact with the die 37 in the outer
punch pressing step (the intermediate punch 34 is
pressed toward the die 37), whereby the intermediate
punch inclined portion 34a is brought into contact
with the bottomed container inclined portion 32a as
illustrated in Fig. 9 (intermediate punch pressing
- 17
step).
[0028] Subsequently, as illustrated in Fig. 10 and
Fig. 11, an end surface of the bottomed container 32
is pressed by the outer punch 35, and the
intermediate punch 34 is moved upward. Consequently,
a gap between the intermediate punch inclined portion
34a and the die inclined portion 37a gradually
becomes larger, which makes it possible to perform
the thickening while suppressing buckling by
sandwiching the bottomed container inclined portion
32a by the intermediate punch inclined portion 34a
and the die inclined portion 37a (thickening step).
The cross-sectional views in Fig. 10 and Fig. 11
illustrate states in the middle of the thickening and
after the thickening respectively.
[0029] After the thickening step, the inner punch 33,
the intermediate punch 34, the outer punch 35, and
the knockout 3 6 are moved upward, and the bottomed
container 32 is detached from the die 37. A sheet
thickness of the bottomed container inclined portion
32a is 8 mm, and thus the thickness can be increased
to twice an original sheet thickness of 4 mm without
any occurrence of folding due to buckling. Further,
a smooth shape is achieved without any large step in
a boundary between a thickened portion and a nonthickened
portion.
Further, at the time of the thickening, a force
in a direction perpendicular to the intermediate
punch inclined portion 34a acts on the intermediate
1!
punch 34, but since this force acts in such a
direction as to press the intermediate punch 3 4
against the inner punch 33 (inward in a diameter
direction (center direction)}, there occurs no gap in
a boundary between the inner punch 33 and the
intermediate punch 34 and a burr is not generated.
[0030] Here, in the state illustrated in Fig. 7 , if
the end portion of the bottomed container 32 is
pressed by the outer punch 35 without the
intermediate punch 3 4 abutting on the bottomed'
container 32, the bottomed container inclined portion
32a is not sufficiently constrained, and accordingly,
buckling occurs in the bottomed container inclined
portion 32a as illustrated in Fig. 12. Therefore, by
executing the thickening process by the outer punch
3 5 while constraining the bottomed container inclined
portion 32a by sandwiching it by the intermediate
punch 34 and the die 37, it is possible to suppress
the buckling in the bottomed container inclined
port ion 32a.
[0031] In the above-described examples, an angle
made by the bottomed container inclined portions 2 2a,
32a and the horizontal direction is 45° , but it is
desirably not less than 20° nor more than 70° . This
is because, if the angle made by the bottomed
container inclined portion 2 2a, 32a and the
horizontal direction is less than 20° , a flow of a
material from bottomed container vertical wall
portions 2 2b, 32b to the bottomed container inclined
- 19 -
portions 22a, 32a becomes worse, and a load required
for the forming becomes large. Further, this is
because, if the angle made by the bottomed container
inclined portions 22a, 32a and the horizontal
direction is over 7 0° , a contact length of the
workpieces 21, 31 and the mold becomes long, and
accordingly a frictional force becomes large, so that
a load required for the forming becomes large. Note
that the bottomed container vertical wall portions
22b, 32b mean portions of the bottomed containers 22,
32 on a side closer to the outer punches 25, 35 than
the bottomed container inclined portions 22a, 32a.
[00 32] Hitherto, the present invention has been
described together with various embodiments, but the
present invention is not limited only to these
embodiments, and changes and so on can be made within
the scope of the present invention.
In the above-described examples, SAPH590 is used
as the workpiece, but it is not limited to an ironbased
material, but an aluminum-based metal, a
titanium-based metal, or the like is usable.
[0033] Further, in the above-described embodiments,
the examples where the bottomed container whose
inclined portion is thickened is manufactured from
the disk-shaped workpiece by the press-work having
one process, but the present invention is also
applicable to a press-work whose thickening target is
a bottomed container having an inclined portion which
is formed in a separate process, that is, to a press-
- 20 -
work whose starting state is Fig. 3 or Fig. 7.
INDUSTRIAL APPLICABILITY
[0034] The present invention is usable for
thickening an inclined portion rising from a bottom
surface portion of a bottomed container.

CLAIMS
[Claim 1] A press-work method using a press mold
which includes an inner punch, an intermediate punch
disposed along an outer periphery of the inner punch
and having an intermediate punch inclined portion at
a leading end, an outer punch disposed along an outer
periphery of the intermediate punch, and a die having
a die inclined portion facing the intermediate punch
inclined portion, central axes of all of which are
disposed coaxially, the method comprising
a thickening step of, while constraining a bottom
portion of a bottomed container by the inner punch
and the die, pressing an end portion of the bottomed
container by the outer punch and moving the
intermediate punch in a direction opposite a
direction in which the outer punch is pressed, to
thereby thicken a bottomed container inclined portion
of the bottomed container sandwiched by the
intermediate punch inclined portion and the die
inclined portion.
[Claim 2] A press-work method using a press mold
which includes an inner punch having an inner punch
flat portion and an inner punch inclined portion at a
leading end, an intermediate punch disposed along an
outer periphery of the inner punch and having an
intermediate punch inclined portion at a leading end,
an outer punch disposed along an outer periphery of
the intermediate punch, and a die having a die
inclined portion disposed to face the intermediate
- 22
punch inclined portion, central axes of all of which
are disposed coaxially, the inner punch inclined
portion being formed at an end portion, of the
leading end of the inner punch, on a side adjacent to
the intermediate punch inclined portion, the method
comprising:
an outer punch pressing step of, while
constraining a bottom portion of a bottomed container
by the inner punch flat portion and the die, pressing
an end portion of the bottomed container by the outer
punch to thereby bring a bottomed container inclined
portion, of the bottomed container, which extends
along the inner punch inclined portion and the
intermediate punch inclined portion, into contact
with the die inclined portion;
an intermediate punch pressing step of pressing
the intermediate punch in a direction of the die
against the bottomed container which is brought into
contact with the die inclined portion in the outer
punch pressing step, to bring the intermediate punch
inclined portion into contact with the bottomed
container inclined portion; and
a thickening step of pressing the outer punch
against the bottomed container which is brought into
contact with the intermediate punch inclined portion
in the intermediate punch pressing step, and moving
the intermediate punch in a direction opposite a
direction in which the outer punch is pressed, to
thereby thicken the bottomed container inclined
portion.
[Claim 3] The press-work method according to claim 1,
coiRpris-ing, .before the thickening'step, a forming
step of pressing a disk-shaped workpiece into the die
by the inner punch and the intermediate punch to form
the bottomed container in which the bottomed
container inclined portion.is formed at a position
sandwiched by the intermediate punch inclined portion
and the die inclined portion.
[Claim 4] The press-work method according to claim 2,
comprising, before the outer punch pressing step, a
forming step of pressing a disk-shaped workpiece into
the die by the inner punch and the int ermedia.te punch
to form the bottomed container in which the bottomed
container inclined portion is formed at a position
sandwiched by the inner punch inclined portion and
the intermediate punch inclined portion, and the die
inclined portion.
[Claim 5] The bottomed container manufactured by the
press-work method according to claim X , wherein a
thickening ratio of a thickness of the bottomed
container inclined portion is 1.5 times or more.
[Claim 6] The bottomed container manufactured by the
press-work method according to claim 2 , wherein a
thickening ratio of a thickness of the bottomed
container inclined portion is 1.5 times or more.