U.S. patent application number 10/354670 was filed with the patent office on 2004-08-05 for shaping method and apparatus of thin metal sheet.
Invention is credited to Amino, Hiroyuki, Lu, Yan, Matsubara, Shigeo.
Application Number | 20040148997 10/354670 |
Document ID | / |
Family ID | 33132655 |
Filed Date | 2004-08-05 |
United States Patent
Application |
20040148997 |
Kind Code |
A1 |
Amino, Hiroyuki ; et
al. |
August 5, 2004 |
Shaping method and apparatus of thin metal sheet
Abstract
The invention provides a method and an apparatus capable of
accurately shaping, within a short time, cubic products such as
trial products for press molding for mass production without
limitation of a molding shape. While edge portions of a blank are
clamped, a mold punch having a molding shape is pushed from a sheet
thickness direction to conduct rough forming. While the mold punch
is kept pushed, shaping is conducted by use of a rod-like tool from
an opposite side to the mold punch sandwiching the sheet
thickness.
Inventors: |
Amino, Hiroyuki; (Shizuoka,
JP) ; Matsubara, Shigeo; (Tokyo, JP) ; Lu,
Yan; (Shizuoka, JP) |
Correspondence
Address: |
Striker, Striker & Stenby
103 East Neck Road
Huntington
NY
11743
US
|
Family ID: |
33132655 |
Appl. No.: |
10/354670 |
Filed: |
January 30, 2003 |
Current U.S.
Class: |
72/297 |
Current CPC
Class: |
B21D 22/16 20130101;
B21D 11/02 20130101; B21D 25/02 20130101 |
Class at
Publication: |
072/297 |
International
Class: |
B21D 011/02 |
Claims
1. A shaping method of a thin metal sheet comprising the steps of:
clamping edge portions of a thin metal sheet; pushing under this
state a mold punch finished to a product shape from below a sheet
thickness direction; conducting forming to shape a rough forming
body having a top portion and side portions; and finishing said
rough forming body to a product shape by use of a tool capable of
moving three-dimensionally with said mold punch as a mold surface
from an opposite side to said mold punch sandwiching the sheet
thickness while said mold punch is kept under a pushed state.
2. A shaping method of a thin metal sheet according to claim 1,
wherein said step of finishing to the product shape is carried out
by using a rod-like tool and causing said rough forming body to
undergo local plastic deformation.
3. A shaping method of a thin metal sheet according to claim 1,
wherein said step of finishing to the product shape is carried out
in two stages of using an elastic tool and pushing said elastic
tool to said mold punch from an opposite side to said mold punch
while sandwiching the sheet thickness to cause local compression
molding, and shaping said rough forming body to a finish shape by
use of a rod-like tool.
4. A molding apparatus of a thin metal sheet comprising: a bed
equipped with a mounting frame; a plurality of wrinkle support
devices arranged on said bed with intervals among them and clamping
edge portions of a thin metal sheet in a sheet thickness direction;
a mold punch arranged inside a recess chamber which is formed in
said bed more inward than said wrinkle support devices; a mold
punch elevation device for pushing said mold punch into said thin
metal sheet supported by said wrinkle support devices; a secondary
molding device fitted to said mounting frame movably in three-axis
directions; and a tool fitted to said secondary molding device for
conducting shaping of a rough forming body shaped by said mold
punch in cooperation with said mold punch.
5. A molding apparatus of a thin metal sheet according to claim 4,
wherein said tool is two kinds of tools, that is, a local
compression molding tool having a fitting portion and an elastomer,
and a rod-like hard tool, the tools being removably fitted to a
tool holder of said secondary molding device.
Description
TECHNICAL FIELD
[0001] This invention relates to a shaping method of a thin metal
sheet and an apparatus for the method.
BACKGROUND ART
[0002] Methods and means for processing a thin metal sheet into a
cubic shape are described in JP-A-7-132329, for example. In this
prior art technology, edge portions of a thin metal sheet are fixed
to a frame-like table capable of moving up and down, and a
pole-like push body is implanted inside a space encompassed by the
frame-like table. To conduct shaping, the pole-like push body is
brought into contact with a lower surface of the thin metal sheet,
and a rod-like tool capable of moving in a Z-axis direction is
positioned on the upper surface side of the thin metal sheet. While
the rod-like tool is moved round the push body, the frame-like
table is lowered so as to serially cause plastic deformation of the
thin metal sheet.
[0003] This shaping method is believed suitable for producing a
trial product. Since the rod-like tool is allowed to describe a
contour line orbit to serially shape the shape of the overall
product, however, the method is time-consuming from the start till
the end of shaping, and mass-production of 500 pieces/month is
difficult to attain in practice.
[0004] Though this shaping method can shape a simple expanding
shape such as a cone and a pyramid, the method is not free from the
limitation that it cannot easily shape an angular portion of a
longitudinal wall and cannot either shape easily a product having
grooves and protrusions on its bottom surface having a large
area.
[0005] Since the prior art technology is based on expansion molding
exclusively utilizing "stretching" of a material as its processing
principle, the resulting product is inferior in a large drop of its
sheet thickness and its dimensional accuracy to those obtained by
press molding. Therefore, the method is not entirely suitable for
trial production for mass-producing press moldings and for
producing trial products.
DISCLOSURE OF THE INVENTION
[0006] To solve the problems described above, it is a first object
of the invention to provide a shaping method that can shape
accurately and moreover, within a short time, cubic products such
as trial products for mass-producing press moldings from a thin
metal sheet without limitation of a molding shape.
[0007] It is a second object of the invention to provide an
apparatus that can shape accurately and moreover, within a short
time, cubic products such as trial products for mass-producing
press moldings without limitation of a molding shape, and has a
simple construction.
[0008] A shaping method of a thin metal sheet for accomplishing the
first object described above comprises the steps of clamping edge
portions of a thin metal sheet; pushing under this state a mold
punch finished to a product shape from below a sheet thickness
direction; conducting a forming operation to shape a rough forming
body having a top portion and side portions; and finishing the
rough forming body to a product shape by use of a tool capable of
moving three-dimensionally with the mold punch as a mold surface
from an opposite side to the mold punch sandwiching the sheet
thickness while the mold punch is kept under a pushed state.
[0009] The step of finishing the rough forming body to the product
shape may employ a method that uses a rod-like tool and cause the
rough forming body to undergo local plastic deformation.
Furthermore, it is possible to use an elastic tool in a first stage
and to push the tool to the mold punch from an opposite side to the
mold punch sandwiching the sheet thickness so as to cause local
compression molding, and to conduct finish shaping by use of the
rod-like tool in the second stage. According to the latter, a high
precision molding operation can be conducted even in a complicated
shape locally having projections and recesses.
[0010] To accomplish the second object, the invention provides a
molding apparatus of a thin metal sheet comprising a bed equipped
with a mounting frame;
[0011] a plurality of wrinkle support devices arranged on the bed
with intervals each other for clamping edge portions of a thin
metal sheet in the sheet thickness direction; a mold punch arranged
inside a recess chamber which is formed in the bed more inward than
the wrinkle support devices;
[0012] a mold punch elevation device for pushing the mold punch
into the thin metal sheet supported by the wrinkle support devices;
a secondary molding device fitted to the mounting frame movably in
three-axis directions; and a tool fitted to the secondary molding
device for conducting shaping of a rough forming body shaped by the
mold punch in cooperation with the mold punch.
[0013] According to this construction, a mold punch corresponding
to a product shape is prepared and is fitted to the mold punch
elevation device and high precision shaping can be carried out.
[0014] The wrinkle support devices are arranged on the bed and do
not move up and down. In other words, unlike the prior art shaping
apparatus, a frame-like table for clamping the edge portions of the
thin metal sheet in the direction of the sheet thickness, capable
of moving up and down, is not necessary. The invention neither
requires a mechanism for lowering the frame-like table in
accordance with the progress of shaping nor balance movement
control. Therefore, the construction of the apparatus can be
simplified. In addition, the height of the apparatus can be
lowered, and conveying of the thin metal sheet and withdrawal of
the product can be carried out at a position close to a ground
level.
[0015] The invention is suitable for shaping large-scale products
such as outer panels typified by automobile components such as a
fender and a food outer panel, airplane components, building
materials, kitchen products, bath products and electric
appliances.
[0016] Other features and advantages of the invention will become
more apparent from the following detailed description, but the
invention is not particularly limited to the construction of the
embodiments so long as the basic feature of the invention is
satisfied. It will be therefore obvious that those skilled in the
art can make various changes and modifications without departing
from the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a longitudinal sectional side view showing a state
before the start of shaping in a metal thin sheet shaping apparatus
according to an embodiment of the invention.
[0018] FIG. 2 is a longitudinal sectional side view showing a state
of use of the apparatus according to the invention.
[0019] FIG. 3 is a plan view.
[0020] FIG. 4 is a longitudinal sectional front view.
[0021] FIG. 5 is a partial cut-away side view showing the
arrangement of a tool for finishing a product into shape and a
secondary molding device.
[0022] FIG. 6 is a partial enlarged side view showing a state where
shaping is carried out by use of a first kind of a tool for
finishing the product into shape.
[0023] FIG. 7 is a partial enlarged side view showing a state where
shaping is carried out by use of a second kind of a tool for
finishing the product into shape.
[0024] FIG. 8 is a partial perspective view showing another example
of the secondary molding device according to the invention.
[0025] FIG. 9 is a partial sectional view of FIG. 8.
[0026] FIGS. 10A, 10B and 10C are explanatory views each showing an
example of a shaping tool.
[0027] FIGS. 11A and 11B are explanatory views each showing an
example of a final shaping tool.
[0028] FIGS. 12A to 12D are sectional views each showing step-wise
a shaping example according to the invention.
[0029] FIGS. 13A to 13C are partial sectional views each showing
step-wise another example of the shaping example according to the
invention.
[0030] FIGS. 14A to 14C are partial sectional views each showing
step-wise still another shaping example according to the
invention.
[0031] FIG. 15 is a perspective view showing an example of a
product to which the invention is applied.
[0032] FIG. 16 is a perspective view showing another example of a
product to which the invention is applied.
[0033] FIGS. 17A to 17C are sectional views each showing step-wise
a shaping step of the product shown in FIG. 16.
DETAILED DESCRIPTION OF THE INVENTION
[0034] Embodiments of the invention will be hereinafter explained
with reference to the accompanying drawings.
[0035] FIGS. 1 to 4 show a shaping apparatus of a thin metal sheet
according to a first embodiment of the invention.
[0036] Reference numeral 1 denotes a bed or frame (hereinafter
called "bed"). A recess chamber 11 opening to an upper surface 10
is defined in a center region. An elevation actuator 2 such as a
hydraulic cylinder is fixedly disposed at a lower part of the
recess chamber 11. A mold-fitting disk 3 is interconnected to an
output portion of the elevation actuator 2. A mold punch 4 finished
into a cubic shape corresponding to a shape of a product is
removably fitted to the mold-fitting disk 3.
[0037] The mold punch 4 generically represents those that are
called "formed type" or a "master mold", and includes a top portion
and side portions. The mold punch 4 is generally formed of a metal
material such as a steel material, but may be formed of FRP in some
cases. The mold punch 4 locally has a concavo-convexity portion 40
besides a flat surface shape, and the concavo-convex portion 40
includes a protrusion, a projection, a recess, a groove, and so
forth.
[0038] Reference numeral 5 denotes a plurality of wrinkle support
devices arranged with a predetermined interval each other so as to
encompass the opening of the recess chamber 11 on the bed outside
the recess chamber 11. Each wrinkle support device 5 includes a die
50 for supporting an edge portion of a thin sheet W, a support disk
51 opposing the die 50, a block-like main body 5a having a support
actuator 52 for pressurizing the support disk 51 and a movement
actuator 5b fixed on the bed at the back of the main body 5a and
having an output portion interconnected to the main body 5a, as
shown in FIG. 6. The wrinkle support devices 5 can be operated
separately. The number of the wrinkle support devices 5 and their
operation forms (the support actuator 52 alone or the support
actuator 52 and the movement actuator 5b) are selected in
accordance with the shape of the thin sheet, its mechanical
properties and shapes to be molded.
[0039] Reference numeral 6 denotes a secondary molding device
capable of moving above the bed 1. The secondary molding device 6
includes a mounting frame 6a provided to the bed 1 so as to avoid
the wrinkle support devices 5 and a main shaft body 6b mounted to
the mounting frame 6a. The main shaft body 6b includes a tool
holder 6c to which a tool 7 for local compression molding and a
tool 8 for shaping are removably fitted as will be explained
later.
[0040] The mounting frame 6a includes four or more columns 69 whose
lower portions are fixed to the bed 1, a pair of parallel X-axis
rails 60 transversely supported by the top portions of these
columns 69, and a Y-axis rail 61 supported by the X-axis rails 60
and 60. A numerical control type driving mechanism 62 for moving
the Y-axis rail 61 along the X-axis rails 60, 60 is mounted to the
Y-axis rail 61.
[0041] The main shaft body 6b is mounted on the Y-axis rails 61,
and has a numerical control type driving mechanism 63 for moving
along the Y-axis rail 61. The main shaft body 6b has at its lower
part the tool holder 6c extending toward the bed. A numerical
control type driving mechanism 64 for moving the tool holder 6c or
a slide having the tool holder 6c thereon in a Z-axis direction is
mounted to the top portion of the main shaft body 6b. The driving
mechanisms 62, 63 and 64 are electrically connected to a
controller, not shown, and can freely adjust the position of the
tool removably fitted to the tool holder 6c in accordance with the
control signal from the controller.
[0042] The tool holder 6c has a chuck mechanism. The chuck
mechanism is arbitrary. This embodiment includes an extensible
chuck 600 having a fastening nut 601 and a split sleeve 602 fitted
into a taper hole of the chuck 600 as shown in FIG. 5.
[0043] Reference numeral 7 denotes the tool for local
compression-molding. This tool 7 includes a fitting portion 70 to
the split sleeve 602 of the tool holder 6c and an elastomer 71 such
as urethane rubber for locally applying a strong pressure to the
thin metal sheet W and shaping it in cooperation with the
concavo-convexity portion 40 of the mold punch 4 as shown in FIGS.
4 and 5.
[0044] Reference numeral 8 denotes a tool for shaping, formed of a
hard material such as a super-hard alloy. This tool 8 includes a
fitting portion 80 to the split sleeve 602 of the tool holder 6c
and a push portion 81 for shaping detailed shapes of the thin metal
sheet W and finishing the work as a whole in cooperation with the
mold punch 4 as shown in FIG. 5. The fitting portions 70 and 80 of
both the tools 7 and 8 have the same outer diameter.
[0045] The construction shown in the drawings represents a mere
example of the invention, and other constructions may well be
employed, too.
[0046] For example, though this embodiment uses an AC servo motor
as the moving mechanism of the secondary molding device 6, a linear
motor may be used instead, as shown in FIGS. 8 and 9. Reference
numeral 65 denotes a guide rail. Reference numeral 66 denotes a
magnetic plate. Reference numeral 67 denotes a coil slider.
Reference numeral 68 denotes a linear scale.
[0047] The tool 8 for shaping may have a spherical push portion 81
at its distal end as shown in FIG. 10A. Alternatively, as shown in
FIG. 10B, it may have at the distal end a recess portion 82 having
curvature and rotatably dispose a hard ball 81' in the recess
portion 82. Still alternatively, a liquid charging port 83
communicating with the recess portion 82 may be formed as shown in
FIG. 10C to supply a lubricant thereinto.
[0048] The tool 8 for shaping may be rotatable relative to the tool
holder 6c. FIG. 11A shows this example. A rotary shaft 6d is
disposed at the lower part of the tool holder 6c so as to be
relatively rotatable, and the tool 8 is fitted to the rotary shaft
6d eccentrically with the axis of the rotary shaft 6d. Any rotation
means can be used, however, in this example, a driving motor 6e is
mounted to the tool holder 6c and the motor output is transmitted
to the rotary shaft 6d through a transmission element 6f such as a
pulley and a gear.
[0049] Next, a shaping method of a thin metal sheet according to
the invention will be explained.
[0050] To start shaping, the mold punch 4 finished to the molding
shape is fixed to the mold-fitting disk 3 by use of a bolt and a
nut. When the preparation is ready in this way, the thin metal
sheet W is conveyed onto the bed 1 by conveyor means such as a
magnet chuck. In that case, it is preferable that the movement
actuator 5b of the wrinkle support device 5 has been operated to
move back the main body 5a and to move the support disk 51 towards
the open side by each support actuator 52 of the wrinkle support
device 5. Then, the main body 5a is moved forward with conveying of
the thin metal sheet W and the edge portions of the thin metal
sheet W are inserted between the main body 5a and the die 50. The
necessary support actuator 52 is operated to lower the support disk
51 to clamp the edge portions of the thin metal sheet W with the
die 50.
[0051] FIGS. 1 and 12A show this state. The thin metal sheet W is
spread over the recess chamber 11 and the mold punch 4 is
positioned below the thin metal sheet W. The secondary molding
device 6 is located at the side standby position. The tool 7 for
local compression molding or the tool 8 for shaping is fitted at
this time to the tool holder 6c in accordance with the product
shape. When the product has a relatively simple shape such as a
shape not having concavo-convexity at its top, the tool 8 for
shaping may be used. Otherwise, the tool 7 for local compression
molding is fitted for the first stage shaping.
[0052] Next, the elevation actuator 2 is operated to raise the mold
punch 4. The mold punch 4 forcibly comes into contact with the
lower surface of the thin metal sheet W. As the mold punch 4
successively rises, the thin metal sheet W is caused to undergo
plastic deformation in the direction of the sheet thickness along
the shape of the mold punch 4, and is roughly formed into a cubic
shape having the top and sidewall portions by the squeeze
operation. Symbol W1 denotes a rough forming body.
[0053] The pressing force of the support actuator 52 of the
necessary wrinkle support device 5 is reduced during rough forming
in accordance with the characteristics such as the shape, sheet
thickness, and elongation of the thin metal sheet W, the material,
to promote the flow of the material. When this means is not yet
sufficient, the movement actuator 5b is operated to move forth the
main body 5a. In consequence, the material can be prevented from
tearing, and the overall shape is shaped with the exception of the
mold punch local portion (protuberance in this embodiment) 40 as
shown in FIG. 12B.
[0054] Next, while the mold punch 4 is kept at the raised position,
the tool 7 for local compression molding is moved immediately above
the mold punch local portion 40. This positioning can be achieved
by the movement of the Y-axis rail 61 relative to the X-axis rails
60 by the driving mechanism 62 and the movement of the main shaft
body 6b relative to the Y-axis rail 61 by the driving mechanism
63.
[0055] Next, the tool 7 for local compression molding immediately
above the mold punch local portion 40 is moved by means of the
driving device 64 in the Z-axis direction. Consequently, the blank
portion WP that has been out of contact from, gently contact with,
the mold punch local portion 40 undergoes compression molding as
the elastomer 71 is pushed against the mold punch local portion 40,
to profile the mold punch local portion 40 as shown in FIG. 12C.
Symbol WP1 denotes a compression molding portion.
[0056] Next, the main shaft body 6b is moved sideward, the chuck is
loosened and the tool 7 for local compression molding is removed
from the tool holder 6c and is replaced by the tool 8 for
shaping.
[0057] The main shaft body 6b is moved in the X-, Y- and Z-axis
directions by the respective driving mechanisms 62, 63 and 64, and
the push portion 81 (81') of the tool 8 for final shaping is
brought into high pressure contact with the compression molding
portion WP1 in the region of the mold punch local portion 40 to
cause local plastic deformation. In this way, the precise shape of
the details can be shaped as shown in FIG. 12D. Symbol WP2 denotes
a finish local portion. When the main shaft body 6b is moved in the
X-, Y- and Z-axis directions by the respective driving mechanisms
62, 63 and 64, the portions other than the mold punch local portion
40, such as the sidewalls and the boundary portion between the
sidewall and the ceiling can be finished to the final profile.
[0058] In the first step of the invention, the thin metal sheet W
is subjected to free forming inclusive of the squeeze component by
use of the mold punch 4. Therefore, it is not necessary to move the
tool 8 for shaping in the contour line orbit in the second step. In
other words, shaping may well be carried out while the thin metal
sheet W is moved three-dimensionally in accordance with the product
shape and while it is continuously pushed to the mold punch 4.
[0059] After shaping is completed as described above, the main
shaft body 6b is moved to the side standby position by the driving
mechanisms 62, 63 and 64 and the mold punch 4 is moved to the lower
limit. Consequently, the mold punch 4 is removed from the product
W2 and the product W2 remains while being held by the wrinkle
support devices 5. Clamping by the wrinkle support devices 5 is
released and the product W2 is thereafter taken out.
[0060] FIGS. 13A to 13C show another example of local compression
molding and final shaping. The mold punch 4 has a recessed local
portion (recess or groove) 40 and moreover, a protuberance 400 at
the bottom of the local portion.
[0061] In this case, the tool 7 for local compression molding is
moved at least in the Z-axis direction, or serially in the X-axis
direction and/or in the Y-axis direction and then in the Z-axis
direction, while rough forming is conducted by use of the mold
punch 4 as shown in FIG. 13A. When this operation is conducted at
least once, the non-molded portion WP is pushed into, and brought
into high-pressure contact with, the recessed local portion 40 as
the elastomer 71 strongly pushes as shown in FIG. 13B. At this
time, the compression molding portion WP1 has not yet been brought
sufficiently into contact with the recessed local portion 40 by the
strong pressure of the elastomer 71. Therefore, the tool 8 for
final shaping is serially moved under numerical control to bring
the compression molding portion WP1 into contact with the bottom
protrusion 400 forcibly as shown in FIG. 13C. Consequently, high
precision shaping can be carried out.
[0062] FIGS. 14A and 14B show the case where the mold punch 4 has a
convex local portion (projection or protrusion) 40 and moreover, a
recess portion 401 at the top of the local portion. In this case,
too, the non-molded portion WP of the rough forming body W1 is
subjected to local compression molding by use of the tool 7 for
local compression molding as shown in FIG. 14A, and contact
movement of the tool 8 for shaping is used for shaping detailed
portions and for finishing. In this way, high precision shaping can
be carried out.
[0063] When a hard ball 81' capable of freely rotating is used as
the tool 8 for final shaping as shown in FIG. 10B, contact with the
material changes from sliding contact to rolling contact.
Therefore, it becomes possible to prevent exothermy due to
friction, to reduce the occurrence of machining scratches of the
shaped article and to prevent spring-back.
[0064] When the tool 8 for final shaping is rotatable as shown in
FIG. 11A, shaping accuracy can be improved because as shown in FIG.
11B pressure is applied to the shaping region eccentrically as
well.
[0065] The method of the invention can take various forms of
use.
[0066] 1) The method of the invention includes the step of
operating only a part of the plurality of wrinkle support devices 5
to conduct local fixing and local clamping. In other words, the
method includes the step of keeping the pressing force of the
support actuators 52 of the necessary wrinkle support devices 5
unloosened or releasing the pressing force of the support actuator
52 of the necessary wrinkle support devices 5 to the free
state.
[0067] 2) When the shape to be shaped is smooth such as a hood, it
is possible to omit the local compression molding step and to
conduct shape-fixing for eliminating spring-back by contact
movement by the tool 8 for shaping in succession to rough forming,
or to conduct shaping of the fine portions and finish shaping.
[0068] The invention is suitable for trial production of various
large-scale cubic products. For example, the invention can easily
and accurately produce outer panels of an automobile typified by a
fender and a hood outer plate shown in FIG. 15 and a hood inner
plate shown in FIG. 16.
[0069] Explanation will be given in further detail. The product
shown in FIG. 16 has a size of 885.times.970 mm and includes
sidewalls WS and a ceiling wall WT connected at right angles to the
sidewalls WS. Moreover, the ceiling wall WT has a complicated shape
having a plurality of groove-like recess portions WP2. The
groove-like recess portion WP2 has a bottom width of 20 mm, an open
width of 32 mm and a depth of 13 mm.
[0070] To shape such a product, the invention uses the mold punch 4
having groove-like local portions 40 corresponding to the
groove-like recess portions WP2 as shown in FIG. 17A and pushes the
punch 40 into the thin metal sheet to freely shape the rough
forming body W1. Next, the non-molded portion WP of the rough
forming body W1 is subjected to local compression molding by
bringing the tool 7 for local compression molding into
high-pressure contact with the local portion 40 as shown in FIG.
17B. The tool 8 for shaping is then used to replace the tool 7 for
local compression molding. The tool 8 is moved while keeping
contact with the local portion 40 to conduct finish shaping as
shown in FIG. 17C. In the rough forming stage, the sidewalls WS do
not keep close contact with the side surface 41 of the mold punch,
but keep floating. When the tool 8 is moved three-dimensionally and
the sidewalls WS are pushed to the mold punch side surface 41,
however, sharp sidewalls can be shaped.
[0071] The shaping condition used in practice is as follows.
[0072] The thin metal sheet is an SPCD plated steel sheet having a
sheet thickness of 0.7 mm and a size of 1,050.times.1,130 mm.
[0073] The rough forming condition includes a wrinkle support force
of 70 tonf and uses an oil lubricant as a lubricant.
[0074] As the elastic tool urethane rubber having a diameter 50
mm.times.70 mm is used and local compression is conducted under a
push condition of 20% compression.
[0075] As the rod-like tool, a super-hard alloy having a diameter
of 10 mm is used, and finish shaping is conducted under the moving
condition (shaping pitch in the direction of height) of 0.5 mm.
[0076] As a result, the shaping time is 2 hours, and accuracy of
the product obtained is .+-.0.5 mm, which satisfy the required
quality. The sheet thickness reduction ratio is within 20%.
[0077] Industrial Applicability
[0078] The invention is suitable for trial production of various
large-scale cubic products.
* * * * *