U.S. patent application number 12/450074 was filed with the patent office on 2010-04-08 for process for manufacturing ring-shaped member.
Invention is credited to Naoki Fuji, Toshiaki Kanemitsu, Katsuhiko Nakayama, Kazuyuki Oda.
Application Number | 20100083727 12/450074 |
Document ID | / |
Family ID | 39759069 |
Filed Date | 2010-04-08 |
United States Patent
Application |
20100083727 |
Kind Code |
A1 |
Kanemitsu; Toshiaki ; et
al. |
April 8, 2010 |
PROCESS FOR MANUFACTURING RING-SHAPED MEMBER
Abstract
A yield which is a ratio of the weight of a ring-shaped member
to that of a stock material, and a yield which is a ratio of the
ring-shaped member to a blank are improved, and the cost is
reduced. In a method of producing a ring-shaped member in which a
ring-shaped member is obtained from a longitudinally elongated
annular blank 3, a pair of linking portions 3b, 3c are outward
expanded from the inner side of the blank 3, and a pair of arcuate
portions 3d are pressed from the outer side toward the inner side
to be pressingly expanded, thereby shaping into a ring-shaped
member.
Inventors: |
Kanemitsu; Toshiaki; (Hyogo,
JP) ; Nakayama; Katsuhiko; (Hyogo, JP) ; Fuji;
Naoki; (Hyogo, JP) ; Oda; Kazuyuki; (Hyogo,
JP) |
Correspondence
Address: |
BACON & THOMAS, PLLC
625 SLATERS LANE, FOURTH FLOOR
ALEXANDRIA
VA
22314-1176
US
|
Family ID: |
39759069 |
Appl. No.: |
12/450074 |
Filed: |
March 12, 2007 |
PCT Filed: |
March 12, 2007 |
PCT NO: |
PCT/JP2007/000200 |
371 Date: |
September 10, 2009 |
Current U.S.
Class: |
72/362 |
Current CPC
Class: |
B21D 53/16 20130101 |
Class at
Publication: |
72/362 |
International
Class: |
B21D 31/00 20060101
B21D031/00 |
Claims
1. A method of producing a ring-shaped member in which a
ring-shaped member is obtained from a longitudinally elongated
annular blank having: a pair of arcuate portions which are opposed
to each other in ends in a longitudinally elongated direction; and
a pair of linking portions which are opposed to each other in both
sides in lateral directions perpendicular to the longitudinally
elongated direction, and which link together terminals of said pair
of arcuate portions, wherein said pair of linking portions are
outward expanded from an inner side of said blank, and said pair of
arcuate portions are pressed from an outer side toward an inner
side to be pressingly expanded, thereby shaping into a ring-shaped
member. A method of producing a ring-shaped member in which a
ring-shaped member is obtained from a longitudinally elongated
annular blank having: a pair of arcuate portions which are opposed
to each other in ends in a longitudinally elongated direction; and
a pair of linking portions which are opposed to each other in both
sides in lateral directions perpendicular to the longitudinally
elongated direction, and which link together terminals of said pair
of arcuate portions, wherein said pair of linking portions are
outward expanded from an inner side of said blank, thereby shaping
inflated linking portions, said pair of arcuate portions are
pressed from an outer side toward an inner side to be pressingly
expanded, thereby shaping enlarged arcuate portions having a radius
of curvature which is larger than a radius of curvature of said
arcuate portions, said pair of enlarged arcuate portions are then
pressed from an outer side toward an inner side, thereby shaping
enlarged arcuate portions having a radius of curvature which is
larger than the radius of curvature of said enlarged arcuate
portions, and, while restricting lateral outward expansion of said
pair of inflated linking portions, said pair of inflated linking
portions are shaped into inflated linking portions having a radius
of curvature which is smaller than a radius of curvature of said
inflated linking portions, thereby shaping into a ring-shaped
member.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of producing a
ring-shaped member.
BACKGROUND ART
[0002] Conventionally, a ring-shaped member 1 such as shown in FIG.
9 is produced by a method in which, from a stock material 2 shown
in FIGS. 11(a), (b) and having a predetermined thickness, a
plurality of annular ring-shaped members 1 are punched out in a
single or plural rows by a pressing apparatus.
[0003] In the conventional production method, however, the yield
which is a ratio of the weight of the ring-shaped members 1 to that
of the stock material 2 is poor, and hence the cost of the
ring-shaped member 1 is increased. The reason is that the ratio of
a skeleton S1 and a slug S2 to the ring-shaped member 1 is high in
the material utilization. The term "skeleton" means a frame-like
scrap which remains as a result of punching of the plurality of
ring-shaped members 1. The term "slug" means a plurality of scraps
which are removed by a punch in the process of punching out the
plurality of ring-shaped members 1.
[0004] Therefore, a method of shaping a ring-shaped member shown in
FIGS. 12(a), (b) has been proposed (for example, see Patent
Literature 1).
[0005] The method of shaping a ring-shaped member disclosed in
Patent Literature 1 above includes steps of: continuously bending
the width of an oblong ring-like stock material while preventing it
from being deformed, thereby forming the stock material into a
circular shape; and shaping the circular stock material into a
perfect circular shape.
[0006] As shown in FIG. 12(a), inner and outer rolls 103, 104 which
are opposed and slidably clamp one width of the minor-axis side of
an oblong ring-like stock material 100, and which are rotatable and
movable, and a pair of bending rolls 105 which are movable are
disposed. The inner and outer rolls 103, 104 are rotated in the
direction of arrow F or the opposite direction, to feed the oblong
ring-like stock material 100 in the direction of arrow L or the
opposite direction. While performing the feeding, the pair of
bending rolls 105 are pressed in the direction of arrow G, whereby
a curvature process is gradually performed on a linear portion of
the stock material 100 to shape a circular stock material 101.
[0007] As shown in FIG. 12(b), then, a large-diameter inner roll
106 is fitted onto the inner roll 103 so as to be simultaneously
rotatable, and then internally in contact with the circular stock
material 101. The large-diameter inner roll 106 and the outer rolls
103, 104 are rotated in the direction of arrow F or the opposite
direction, whereby a ring-shaped member 102 which is shaped into a
perfect circular shape can be obtained.
[0008] According to the method of shaping a ring-shaped member, the
circular stock material 101 is obtained from the oblong ring-like
stock material 100, and hence material utilization in which the
ratio of a skeleton and a slug to the perfect circular ring-shaped
member 102 is suppressed to be smaller than that of the skeleton S1
and the slug S2 to the ring-shaped member 1 described with
reference to FIG. 11 is enabled. Therefore, the yield which is a
ratio of the weight of the ring-shaped member 102 to that of the
stock material is improved, and the cost of the ring-shaped member
102 can be reduced.
Patent Literature 1: Japanese Utility Model Application Laying-Open
No. 62-203633
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0009] In the method of shaping a ring-shaped member disclosed in
Patent Literature 1, however, an arcuate portion 107 which remains
in the circular stock material 101, and which has a small radius of
curvature is pressingly expanded from the inner side by a strong
pressing force in the direction of arrow K due to the
large-diameter inner roll 106. When the arcuate portion 107 having
a small radius of curvature is pressingly expanded from the inner
side in this way, large "elongation" occurs in a radially inward
region having a small radius of curvature and in the arcuate
portion 107, so that the thickness is reduced and a stress is
concentrated. In the process of shaping the circular stock material
101 into the perfect circular ring-shaped member 102, therefore,
there is the possibility that the radially inward region of the
arcuate portion 107 cracks. This impairs the yield which is a ratio
of the perfect circular ring-shaped member 102 to the oblong
ring-like stock material 100, and increases the cost.
[0010] The invention has been conducted in order to solve the
problems. It is an object of the invention to provide a method of
producing a ring-shaped member in which, although a yield that is a
ratio of the weight of the ring-shaped member to that of a stock
material can be improved to reduce the cost, a yield that is a
ratio of the ring-shaped member to a longitudinally elongated
annular blank can be improved.
Means for Solving the Problems
[0011] The invention will be described with reference to the
reference numerals used in FIGS. 3 and 4, in order to facilitate
the understanding of the contents of the invention. The invention
provides a method of producing a ring-shaped member in which a
ring-shaped member is obtained from a longitudinally elongated
annular blank (3) having: a pair of arcuate portions (3d) which are
opposed to each other in ends in a longitudinally elongated
direction; and a pair of linking portions (3b, 3c) which are
opposed to each other in both sides in lateral directions
perpendicular to the longitudinally elongated direction, and which
link together terminals of the pair of arcuate portions (3d),
wherein the pair of linking portions (3b, 3c) are outward expanded
from an inner side of the blank (3), and the pair of arcuate
portions (3d) are pressed from an outer side toward an inner side
to be pressingly expanded, thereby shaping into a ring-shaped
member.
[0012] According to the configuration, a ring-shaped member is
obtained from the longitudinally elongated annular blank (3), and
hence material utilization in which the ratio of a skeleton and a
slug to the ring-shaped member is suppressed to a low level as
compared with the case shown in FIG. 11 is enabled, and the yield
that is a ratio of the weight of the ring-shaped member to that of
a stock material can be improved.
[0013] Furthermore, at the same time when the pair of linking
portions (3b, 3c) are outward expanded from the inner side of the
longitudinally elongated annular blank (3), the pair of arcuate
portions (3d) are pressed from the outer side toward the inner side
to be pressingly expanded, whereby the blank (3) is shaped into a
ring-shaped member. Therefore, "elongation" in radially inward
regions of the arcuate portions (3d) in the both ends in the
longitudinally elongated direction of the longitudinally elongated
annular blank (3) is suppressed as far as possible, the thickness
of the radially inward regions can be prevented from being locally
reduced, and stress concentration in the radially inward regions is
relaxed. As a result, the arcuate portions (3d) in the both ends in
the longitudinally elongated direction of the blank (3) can be
prevented from cracking, and the yield which is a ratio of the
ring-shaped member to the longitudinally elongated annular blank
(3) can be improved.
[0014] The invention will be described with reference to the
reference numerals used in FIGS. 3 to 6, in order to facilitate the
understanding of the contents of the invention. The invention
provides a method of producing a ring-shaped member in which a
ring-shaped member is obtained from a longitudinally elongated
annular blank (3) having: a pair of arcuate portions (3d) which are
opposed to each other in ends in a longitudinally elongated
direction; and a pair of linking portions (3b, 3c) which are
opposed to each other in both sides in lateral directions
perpendicular to the longitudinally elongated direction, and which
link together terminals of the pair of arcuate portions (3d),
wherein the pair of linking portions (3b, 3c) are outward expanded
from an inner side of the blank (3), thereby shaping inflated
linking portions (3B, 3C), the pair of arcuate portions (3d) are
pressed from an outer side toward an inner side to be pressingly
expanded, thereby shaping enlarged arcuate portions (3D) having a
radius of curvature which is larger than a radius of curvature of
the arcuate portions (3d), the pair of enlarged arcuate portions
(3D) are then pressed from an outer side toward an inner side,
thereby shaping enlarged arcuate portions (3E) having a radius of
curvature which is larger than the radius of curvature of the
enlarged arcuate portions (3D), and, while restricting lateral
outward expansion, the pair of inflated linking portions (3B, 3C)
are shaped into inflated linking portions (3F, 3F) having a radius
of curvature which is smaller than a radius of curvature of the
inflated linking portions (3B, 3C), thereby shaping into a
ring-shaped member.
[0015] According to the configuration, a ring-shaped member is
obtained from the longitudinally elongated annular blank (3), and
hence material utilization in which the ratio of a skeleton and a
slug to the ring-shaped member is suppressed to a low level as
compared with the case shown in FIG. 11 is enabled, and the yield
that is a ratio of the weight of the ring-shaped member to that of
a stock material can be improved.
[0016] In the process of shaping the longitudinally elongated
annular blank (3) into a ring-shaped member, at a same time when
the pair of linking portions (3b, 3c) are outward expanded from the
inner side of the blank (3), thereby shaping the inflated linking
portions (3B, 3C), first, the pair of arcuate portions (3d) are
pressed from the outer side toward the inner side to be pressingly
expanded, thereby shaping the enlarged arcuate portion (3D).
Therefore, "elongation" in radially inward regions of the arcuate
portions (3d) in the both ends in the longitudinally elongated
direction of the longitudinally elongated annular blank (3) is
suppressed as far as possible, the thickness of the radially inward
regions can be prevented from being locally reduced, stress
concentration in the radially inward regions is relaxed, and the
arcuate portions (3d) in the both ends in the longitudinally
elongated direction of the blank (3) can be prevented from
cracking.
[0017] Furthermore, at a same time when the pair of enlarged
arcuate portions (3D) are pressed from the outer side toward the
inner side to be pressingly expanded, thereby shaping the enlarged
arcuate portions (3E) having a radius of curvature which is larger
than that of curvature of the enlarged arcuate portions (3D), while
restricting lateral outward expansion, the pair of inflated linking
portions (3B, 3C) are shaped into the inflated linking portions
(3F, 3F) having a radius of curvature which is smaller than that of
curvature of the inflated linking portions (3B, 3C), thereby
shaping a ring-shaped member (1). Therefore, the arcuate portions
(3d) of the longitudinally elongated annular blank (3) can be
prevented from cracking, and the yield which is a ratio of the
ring-shaped member (1) to the longitudinally elongated annular
blank (3) can be improved.
[0018] Particularly, the first step of shaping the linking portions
(3b, 3c) of the blank (3) into the inflated linking portions (3B,
3C), and shaping the arcuate portions (3d) into the enlarged
arcuate portions (3D), and the second step of shaping the enlarged
arcuate portions (3D) into the enlarged arcuate portions (3E)
having a radius of curvature which is larger than that of the
enlarged arcuate portions, and shaping the inflated linking
portions (3B, 3C) into the inflated linking portions (3F, 3F)
having a radius of curvature which is smaller than that of the
inflated linking portions are performed to shape the ring-shaped
member (1). While preventing the thickness of the radially inward
regions of the arcuate portions (3d) from being reduced, and
preventing cracking from occurring, therefore, also the
longitudinally elongated annular blank (3) which is thick can be
shaped into a ring-shaped member having a shape such as an annular
shape or a polygonal shape which is approximately annular.
EFFECTS OF THE INVENTION
[0019] According to the invention, by material utilization in which
a ratio of a skeleton and a slug to the ring-shaped member is
suppressed to a low level, the yield that is a ratio of the weight
of the ring-shaped member to that of a stock material can be
improved, and the cost of the ring-shaped member can be reduced.
Moreover, "elongation" in the radially inward regions of the
arcuate portions in the longitudinally elongated annular blank is
suppressed as far as possible, the thickness of the radially inward
regions can be prevented from being reduced, and stress is not
concentrated in the radially inward regions. Therefore, cracking
does not occur in the arcuate portions of the longitudinally
elongated annular blank, and the yield which is a ratio of the
ring-shaped member to the longitudinally elongated annular blank
can be improved. Consequently, the invention is advantageous.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a plan view showing a first embodiment of a step
of punching out blanks from a stock material.
[0021] FIG. 2 is a plan view showing a blank which is punched out
from the stock material of FIG. 1.
[0022] FIG. 3 is a plan view showing an embodiment in a state where
the blank is set in a first die pressing apparatus.
[0023] FIG. 4 is a plan view showing an embodiment of a ring-shaped
member in a state where the ring-shaped member is shaped by the
first die pressing apparatus.
[0024] FIG. 5 is a plan view showing an embodiment in a state where
the ring-shaped member is set in a second die pressing
apparatus.
[0025] FIG. 6 is a plan view showing an embodiment of a ring-shaped
member in a state where the ring-shaped member is shaped by the
second die pressing apparatus.
[0026] FIG. 7 is a plan view showing a second embodiment of the
blank.
[0027] FIG. 8 is a plan view showing another embodiment of the step
of punching out blanks from a stock material.
[0028] FIG. 9 is a plan view showing an example of the ring-shaped
member.
[0029] FIG. 10 is a plan view showing a third embodiment of the
blank.
[0030] FIG. 11 is a plan view showing of a conventional step of
punching out blanks from a stock material, (a) shows single-row
punching, and (b) shows parallel punching.
[0031] FIG. 12 is a view illustrating a method of shaping a
ring-shaped member disclosed in Patent Literature 1.
DESCRIPTION OF REFERENCE NUMERALS
[0032] 1, 1A ring-shaped member [0033] 3, 27 longitudinally
elongated annular blank [0034] 3b, 3c linking portion [0035] 3d
arcuate portion [0036] 3D, 3E enlarged arcuate portion [0037] 3B,
3C, 3F inflated linking portion
BEST MODE FOR CARRYING OUT THE INVENTION
[0038] Hereinafter, preferred embodiments of the method of
producing a ring-shaped member related to the invention will be
described with reference to the drawings.
[0039] As shown in FIG. 1, while feeding a stock material 2 having
a predetermined thickness in the longitudinal direction of the
stock material 2 as indicated by arrow P, a plurality of
longitudinally elongated annular blanks 3 are punched out in series
by a pressing apparatus with being separated from each other by a
predetermined gap 1 in the feeding direction. As the stock material
2, a bar member which is formed by shaping a metal such as copper,
aluminum, iron, or stainless steel into a plate-like member by
rolling or the like may be used, or a stock material which is
originally formed into a plate-like shape may be used.
[0040] As shown in FIG. 2, each of the longitudinally elongated
annular blanks 3 has a small longitudinally elongated hole 3a
having a width w1 in the inner side, and includes: a pair of
arcuate portions 3d, 3d which are opposed to each other in both
ends in the longitudinally elongated direction; and a pair of
linear linking portions 3b, 3c which are respectively on both sides
in the lateral direction perpendicular to the longitudinally
elongated direction, to be opposed to each other, and which link
together terminals of the pair of arcuate portions 3d, 3d.
[0041] As shown in FIG. 3, the longitudinally elongated annular
blank 3 is set in a first die pressing apparatus 4. The first die
pressing apparatus 4 includes a pair of right and left moving
plates 5, a pair of front and rear shaping outer dies 8, and a pair
of front and rear guiding plates 6. The pair of right and left
moving plates 5 are reciprocated in the right and left directions
(the directions of arrows X1, X2) by a reciprocating mechanism
which is not shown, while being guided by the guiding plates 6. A
shaping inner die 7 in which the projected plan view shape has a
rear convex arcuate shape is upward protruded from the tip end of
each of the right and left moving plates 5. The right and left
shaping inner dies 7, 7 stand at positions which are bilaterally
symmetrical about a line Y that is perpendicular to a line X, and
their flat front faces meet each other. The width w2 of the meeting
right and left shaping inner dies 7, 7 is set to a size which is
slightly smaller than the width w1 of the longitudinally elongated
hole 3a of the blank 3, in order that the shaping inner dies can be
fitted into the longitudinally elongated hole 3a.
[0042] The pair of front and rear shaping outer dies 8 are
reciprocated in the front and rear directions (the directions of
arrows Y1, Y2) by a reciprocating mechanism which is not shown,
while being guided by the guiding plates 6. A pressing face 8a
which is vertical upward protruded, and in which the projected plan
view shape is recessed in an arcuate shape is provided in the tip
end of each of the front and rear shaping outer dies 8. The radius
of curvature of the pressing faces 8a are set to a value which is
larger than the radius of curvature of the outer circumferential
faces of the arcuate portions 3d of the longitudinally elongated
annular blank 3.
[0043] The pair of front and rear shaping outer dies 8 are opposed
to each other on the line Y, and placed at positions which are fore
and aft symmetrical about the line X, and the opposing gap is set
to a value which is larger than the dimension in the longitudinally
elongated direction of the longitudinally elongated annular blank
3, in order that the longitudinally elongated annular blank 3 can
be set.
[0044] As shown in FIG. 3, when the longitudinally elongated
annular blank 3 is set in the first die pressing apparatus 4, an
upper die 9 indicated by a dash-dot-dot line is lowered from the
upper side. This causes the upper faces of the guiding plates 6,
the pair of right and left shaping inner dies 7, and the pair of
front and rear shaping outer dies 8 to be pressed by the lower face
of the upper die 9. The upper faces of the blank 3, the shaping
inner dies 7, and the shaping outer dies 8 are opposed to the lower
face of the upper die 9 across a very small gap (a small gap which
allows sliding motion), thereby preventing the blank 3 from
vertically warping.
[0045] In this state, the right and left moving plates 5 are moved
respectively toward the outer sides in the right and left lateral
directions (the directions of arrows X1) perpendicular to the
longitudinally elongated direction of the blank 3, and at the same
time the front and rear shaping outer dies 8 are moved respectively
toward the inner sides in the longitudinally elongated direction
(the directions of arrows Y1). Then, the right and left shaping
inner dies 7 press the linking portions 3b, 3c on the both sides in
the right and left lateral directions of the longitudinally
elongated annular blank 3, from the inner sides toward the outer
sides (the directions of arrows X1) to, as shown in FIG. 4, expand
the portions in the directions of arrows X1 at a uniform large
radius of curvature, and the front and rear shaping outer dies 8
press the arcuate portions 3d at the both ends in the
longitudinally elongated direction of the blank 3, from the outer
sides toward the inner sides (arrows Y1) in the longitudinally
elongated direction of the blank 3, to expand the arcuate portions
at a radius of curvature which is larger than that of the arcuate
portions 3d of FIG. 3. As a result, an oval annual ring-shaped
member 1A such as shown in FIG. 4 is produced which has a pair of
enlarged arcuate portions 3D having a radius of curvature that is
larger than that of the arcuate portions 3d of FIG. 3, and a pair
of inflated linking portions 3B, 3C that are continuous to the
enlarged arcuate portions, and that are arcuately inflated and
curved at a large radius of curvature.
[0046] As described above, the plurality of longitudinally
elongated annular blanks 3 are punched out from the stock material
2 shown in FIG. 1, and the longitudinally elongated annular blanks
3 are shaped by the first die pressing apparatus 4, thereby
producing the ring-shaped member 1A shown in FIG. 4. By the
material utilization in which a ratio of the skeleton S1 and the
slug 2 of FIG. 1 to the ring-shaped member 1A is suppressed to be
lower than that of the skeleton S1 and the slug 2 to the
ring-shaped member 1 described with reference to FIG. 11,
therefore, the yield that is a ratio of the weight of the
ring-shaped member 1 to that of the stock material 2 can be
improved, and the cost of the ring-shaped member 1A can be
reduced.
[0047] Furthermore, the linking portions 3b, 3c on the both sides
in the right and left lateral directions of the longitudinally
elongated annular blank 3 are pressed from the inner sides to the
outer sides in the right and left lateral directions (the
directions of arrows X1) to be expanded in the directions of arrows
X1 as shown in FIG. 4, and at the same time pressed from the outer
sides in the longitudinally elongated direction of the blank 3
toward the inner sides (the directions of arrows Y1) to be expanded
at a radius of curvature which is larger than that of the arcuate
portions 3d, whereby "elongation" in the radially inward regions
which have a small radius of curvature, and which are in the
arcuate portions 3d of the blank 3 is suppressed as far as
possible, and the thickness of the radially inward regions can be
prevented from being reduced. Moreover, a flow of the material
which, on the contrary, may cause the arcuate portions 3d to be
thickened is produced, and stress concentration in the radially
inward regions is relaxed. As a result, cracking does not occur in
the arcuate portions 3d, and the yield which is a ratio of the
ring-shaped member 1A to the longitudinally elongated annular blank
3 can be improved.
[0048] From the state of the first die pressing apparatus 4 shown
in FIG. 4, the right and left shaping inner dies 7 are further
moved in the directions of arrows X1 to expand the linking portions
3b, 3c of the blank 3 from the inner sides, and the front and rear
shaping outer dies 8 are moved in the directions of arrows Y1 to
expand the arcuate portions 3d of the blank 3, whereby shaping to a
shape which is more approximated to an annular shape than the
ring-shaped member 1A seen in FIG. 4 can be performed.
[0049] In the case where the longitudinally elongated annular blank
3 is a thick blank, or in the case where the ring-shaped member 1A
shown in FIG. 4 is shaped more surely to a shape which is more
approximated to an annular shape, furthermore, the ring-shaped
member is set to a second die pressing apparatus 11 shown in FIG. 5
in the next step.
[0050] The second die pressing apparatus 11 includes a pair of
front and rear shaping outer dies 12, and a pair of right and left
restricting dies 13. The shaping outer dies 12 are reciprocated in
the front and rear directions (the directions of arrows Y1, Y2) by
a reciprocating mechanism which is not shown, while being guided by
guiding plates 14, and the restricting dies 13 are reciprocated in
the right and left directions (the directions of arrows X1, X2) by
a reciprocating mechanism which is not shown, while being guided by
the guiding plates 14.
[0051] Each of the pair of front and rear shaping outer dies 12
includes a placing face 12a, and a pressing face 12b which is
vertically upward protruded from the placing face 12a, and in which
the projected plan view shape is recessed in an arcuate shape. The
radius of curvature of the pressing face 12b is set to a value
which is larger than that of the outer circumferential face of the
enlarged arcuate portion 3D in the ring-shaped member 1A shown in
FIG. 4, and the pressing face 12b is formed into an arcuate shape
which extends along a part of the circumferential face of the
ring-shaped member 1 having an annular shape shown in FIG. 6 or a
polygonal shape that is approximately annular. In each of the pair
of right and left restricting dies 13, a restricting face 13a in
which the projected plan view shape is recessed in an arcuate shape
is formed in the end face of the side that is opposed to the
counter restricting die, the radius of curvature of the restricting
face 13a is set to a value which is smaller than the radius of
curvature of the outer circumferential faces of the inflated
linking portions 3B, 3C in the ring-shaped member 1A shown in FIG.
4, and the pressing face 12b is formed into an arcuate shape which
extends along a part of the circumferential face of the ring-shaped
member 1 having an annular shape shown in FIG. 6 or a polygonal
shape that is approximately annular.
[0052] As shown in FIG. 5, when the ring-shaped member 1A is set in
the second die pressing apparatus 11 in a state where the inflated
linking portions 3B, 3C in the ring-shaped member 1A are clamped by
the right and left restricting dies 13 and the enlarged arcuate
portions 3D in the ring-shaped member 1A and the vicinities of the
portions are placed on the placing faces 12a of the shaping outer
dies 12, an upper die 15 indicated by a dash-dot-dot line is
lowered from the upper side. This causes the upper faces of the
ring-shaped member 1A, the shaping outer dies 12, and the
restricting dies 13 are opposed to the lower face of the upper die
15 across a very small gap (a small gap which allows sliding
motion), thereby preventing the ring-shaped member 1A from
vertically warping.
[0053] In this state, the shaping outer dies 12 are moved in the
directions of arrows Y1. Then, the pressing faces 12b of the
shaping outer dies 12 press the enlarged arcuate portions 3D in the
ring-shaped member 1A from the outer sides toward the inner sides
to expand the portions at a large radius of curvature. This causes
the radially outer faces of the enlarged arcuate portions 3D of the
ring-shaped member 1A to be pressed by the arcuately recessed
pressing faces 12b of the shaping outer dies 12 from the outer
sides toward the inner sides. Therefore, the enlarged arcuate
portions are deformed along the pressing faces 12b, and, as shown
in FIG. 6, enlarged arcuate portions 3E having a radius of
curvature which is larger than the radius of curvature of the
enlarged arcuate portions 3D are shaped. In the radially outward
portions of the enlarged arcuate portions 3E, "elongation" occurs,
and "elongation" in the radially inward regions is suppressed as
far as possible, so that the thickness of the radially inward
regions can be prevented from being reduced. Moreover, a flow of
the material which, on the contrary, may cause the enlarged arcuate
portions 3E to be thickened is produced, and stress concentration
in the radially inward regions is relaxed. As a result, cracking
does not occur in the enlarged arcuate portions 3E.
[0054] At the same time when the enlarged arcuate portions 3E are
shaped, the inflated linking portions 3B, 3C in the ring-shaped
member 1A shown in FIG. 5 are expanded in the directions of arrows
X1. At this time, the outer faces of the inflated linking portions
3B, 3C butt against the arcuately recessed restricting faces 13a of
the restricting dies 13, whereby the ring-shaped member 1A is
deformed along the restricting faces 13a while restricting the
ring-shaped member from being excessively expanded in the
directions of arrows X1. Therefore, the inflated linking portions
3B, 3C in the ring-shaped member 1A shown in FIG. 4 are shaped into
inflated linking portions 3F, 3F having a radius of curvature which
is smaller than that of the inflated linking portions 3B, 3C. As a
result, the annular ring-shaped member 1 such as shown in FIGS. 6
and 9 in which the enlarged arcuate portions 3E and the inflated
linking portions 3F are continuous to each other is produced.
[0055] In the process of shaping into the annular ring-shaped
member 1, "elongation" in the radially inward regions of the
enlarged arcuate portions 3D and the inflated linking portions 3B,
3C is suppressed as far as possible, the thickness of the radially
inward regions can be prevented from being reduced, and stress
concentration in the radially inward regions is relaxed. As a
result, the ring-shaped member 1 can be produced without cracking
the enlarged arcuate portions 3D and the inflated linking portions
3B, 3C. Therefore, the yield which is a ratio of the ring-shaped
member 1 to the longitudinally elongated annular blank 3 can be
improved.
[0056] In the above-described embodiment, as shown in FIG. 2, the
longitudinally elongated annular blank 3 in which the width w1 of
the longitudinally elongated hole 3a is small is punched out, and
the blank 3 is produced into a ring-shaped member. Alternatively,
as shown in FIG. 7, a longitudinally elongated annular blank 27
having an oval longitudinally elongated hole 27a in which the width
w3 is sufficiently larger than the width w1 of FIG. 2 may be
punched out, and the blank 27 may be shaped into a ring-shaped
member in the same procedure as the above-described embodiment.
Also in this case, in the same manner as the above-described
embodiment, the yield which is a ratio of the ring-shaped member to
the longitudinally elongated annular blank 27 can be improved, and
the cost of the ring-shaped member can be reduced.
[0057] In the case where a plurality of longitudinally elongated
annular blanks 3, 27 are punched out from the stock material 2
having a predetermined width, as shown in FIG. 8(a), (b), the outer
end faces of the pair of linear linking portions 3b, 3c in the
longitudinally elongated annular blanks 3, 27 can be formed by
using both end faces 2a in the width direction of the stock
material 2, and the pair of arcuate portions 3d which cause the
pair of linear linking portions 3b, 3c to be continuous to each
other can be formed in both end portions in the longitudinal
direction by sharing the stock material 2 with a pressing
apparatus. According to the configuration, material utilization in
which a ratio of scraps to the longitudinally elongated annular
blanks 3, 27 is suppressed to the minimum level is enabled. Namely,
the scraps are reduced to the slug S1 which is punched away in the
process of punching the longitudinally elongated hole 3a or the
oval longitudinally elongated hole 27a, and drum-shaped end plate
portions 2x which exist between the longitudinally elongated
annular blanks 3 or blanks 27 that are arranged in the longitudinal
direction, and that are cut off from the stock material 2, as
indicated by the hatched lines in FIG. 8(a), (b). As a result, the
yield which is a ratio of the weight of the ring-shaped members 1
to that of the stock material 2 can be further improved.
[0058] In the longitudinally elongated annular blanks 3, 27, the
linking portions 3b, 3c which link together the terminals of the
pair of arcuate portions 3d, 3d are not restricted to those which
are formed into a linear shape as shown in FIG. 2, and, for
example, may be formed into a non-linear shape configured by lines
of flexure as shown in FIG. 10. The longitudinally elongated
annular blanks 3, 27 may be obtained by a pressing process such as
cutting or punching on a bar member made of a metal, forging, or
the like, in place of the process of performing punching on the
plate-like stock material 2 as shown in FIG. 1.
* * * * *