Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a die for forming such
as sheet metals of 0.1 to lOmm thick, plastics and die
casts.
Negative angle forming of sheet metals, plastics and
die casts is usually performed by using a slide cam.
By the way,-the negative angle forming referred herein
denotes a processing in which, when a work placed on a lower
die is formed by descending an upper die vertically for
abutment, a formed portion enters from a descending locus of
the upper die into the lower die.
In the conventional negative angle forming of the sheet
metals plastics and die casts, the work is placed on the
lower die and processed laterally by descending the upper
die vertically and driving a driven cam of the lower die.
When the processing is finished and the upper die is
ascended, the passive cam was retreated by means of a
spring. In this case, a former of the driven cam which
forms the work
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by sliding thereon laterally from outside, is formed into a
unit shape as same as a forming shape of the work. However, a
former of the lower die whereon the work is placed, must be
made possible to take out the work by dividing and retreating
5 a negative angle portion into which the lower die has entered
on by deleting the negative angle portion, since the work
must be taken out from the lower die after the processing.
It is not so problematic if the degree of negative angle
is small. However, when the degree of negative angle is large
10 or, for example, when the work takes the form of elongated
frame with grooved section such as a front-pillar outer of
automotive sheet metal parts, since the groove width of the
work is narrow, if the negatively angled lower die is divided
or deleted, it can not be shaped distinctly only by the
15 pressure of the driven can, and also the lower die strength
is deteriorated and the negative angle forming was
practically impossible.
In the negative angle forming by the slide cam, though
the driven can is guided and slid a long distance by a drive
20 can of the upper die, it is not always simple to move the
driven can repetitively to a predetermined position
accurately because a guide member is not always used for
smooth guidance, thus a product is hardly stable in quality
and besides the torsion and strain may occur to necessitate
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correction of the product.
The correction of products having tree-dimensional
curved surfaces and lines such as parts constituting the
automobile body plate like the front-pillar outer is
S practically impossible. Assembling the torsional or strained
parts with the other parts by welding results in a poor
connection therebetween, thus a high quality sheet metal
structure of the automobile can not be provided and a
predetermined product accuracy of the sheet metal forming can
not be maintained.
When the slide cam is used, a large driven cam and heel
must be provided on the side of the lower die where-the work
is placed, or the moving area of the driven cam is
necessitated, thus the lower die area becomes larger and
heavier, results in expensive dies.
The present invention is based on converting the linear
vertical motion of mass-production equipment into rotating
motion. More particularly, the invention provides a die
having a former which is negatively angled when an upper die
is moved linearly against a lower die for forming, wherein a
cylindrical cam member provided with a groove axially on its
peripheral wall is disposed rotatably on the lower die to
form a negative angle former on the grooved edge of the cam
member, the cam member having a pivoting plate, an actuating
cam having the negative angle former being installed on the
upper die oppositely to said cam member, the actuating cam
having a negative angle former, and an auto-return device is
provided on the lower die to rotate and retreat the cam
member to the state where a work W can be taken out from the
lower die after forming, the upper die is positioned at the
top dead center of a press machine, the work W is placed on
the lower die, the upper die starts to descend from the top
dead center, and first the lower face of the actuating cam is
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contacted to the pivoting plate without interfering the
negative angle former of the cam member, which is rotated
clockwise, as the upper die continues to descend further, the
actuating cam urged externally of the die is moved leftward
against the urging force, thereby the work is formed by
negative angle former of the cam member pivoted and the
negative angle former of the actuating cam, after the
actuating cam, the upper die starts to ascend, the actuating
cam is urged externally of the die, moved rightward and
ascended without interfering the work W formed, meanwhile,
the cam member is rotated counterclockwise by the auto-return
device, since the actuating cam which has restrained is
ascended, so that the work W formed can be taken out from the
lower die without interfering the negative angle former of
the cam member.
The drawings show a specific embodiment of the present
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invention, in which
Fig. 1 is a perspective view of an automotive front-
pillar outer processed by press dies of the present
invention,
Fig. 2 is a longitudinal sectional view of press dies,
- Fig. 3 is a plan view of its lower die,
Fig. 4 is a plan view of its upper die,
Fig. 5 is side view of a slide cam,
Fig. 6 is sectional view taken along the line VI-VI of
Fig. 5,
Fig. 7 is a sectional view taken along the line VII-VII
Of Fig. 5,
Fig. 8 is a longitudinal sectional view of press dies
for a front-door trim base of automotive sheet metal parts
of another embodiment, and
Figs. 9A to 9D describe a further embodiment of the
invention.
In the following, the present invention will be
described in detail on the basis of a specific embodiment
shown in the accompanying drawings.
First Embodiment
Fig. 1 shows a schematic view of right and left
finished front-pillar outers which are automotive sheet
metal parts formed by press dies of the present invention.
In the
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figure, the lower one is for the right and the upper one is
for the left.
The front-pillar outer is a portion of a front-door
frame and also a portion of a front-glass frame. Moreover, it
5 constitutes a portion of a frame supporting a roof panel.
Since the front-pillar outer is connected to various parts as
such, it requires a severe product accuracy. If such an
accuracy is not satisfied, the sheet metal body of a good
quality can not be provided.
The front-pillar outer includes three-dimensional curved
surfaces and lines since it constitutes an automobile body.
A portion which is subject to a negative angle forming
by the press dies is indicated at A and has the length of
about 750mm, a section of which is shown as a work W in
15 Fig. 2. That is, after the negative angle forming, the work W
is formed into the state shown by a solid line from the state
shown by a two-dot chain line.
By the way, in the press forming, first the drawing
takes place. Then, the peripheral trimming is performed to
20 the state shown by the two-dot chain line. As the next third
process, the press dies of the present forming process is
used. Fig. 3 shows a plan view of its lower die and Fig. 4
shows a plan view of its lower die and Fig. 4 shows that of
the upper die.
A cylindrical cam member 2 provided with a groove 1
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axially on its peripheral wall is disposed rotatably on the
lower die 3, whose upper surface is shaped so as to be able
to receive the work W. A negative angle former 4 is formed on
the edge of the groove 1 of the cam member 2 near the upper
5 face of the lower die 3.
An auto-return device 5 which rotates and retreats the
cam member 2 to the state shown by the two-dot chain line so
as to take out the work W from the lower die after forming is
embedded in the lower die 3.
In the auto-return device 5 of the present embodiment, a
push pin 7 urged by a coil spring 6 is contacted to the lower
end face of a pivoting plate 8 secured to the other edge of
the groove 1 of the cam member 2.
As the auto-return device 5, an air-pressure or
15 hydraulic pressure device or a link mechanism may be used.
Meanwhile, an actuating cam 11 sliding on the position
opposing the cam member 2 is provided on an upper die 9. As
shown in Fig. 2 and Figs. 5 to 7, the actuating cam 11 is
formed with a negative angle former 12 at a lower end, guided
20 by a side guide 13 and a lower guide 14 and urged externally
of the die by a coil spring 17 provided around a positioning
pin 16 between a seat 15 of the actuating cam 11 and the
upper die 9.
The numeral 18 generally indicates a urethane rubber
25 buffer and 19 denotes a safety suspension bolt of the
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actuating cam 11. Positioning of the actuatinq cam 11 against
the lower die 3 is effected by engaging two positioning
grooves 20 provided on its lower surface to positioning keys
21 projected at the positions of the lower die 3 opposing
5 thereto.
Next, the operation of the press dies will be described.
The upper die 9 is positioned at a top dead center and a
work W is placed on the lower die 3. In ~ig. 2, the work W is
in the state shown by the two-dot chain line, and the cam
10 member 2 is pivoted and retreated to the state shown by the
two-dot chain line by the auto-return device 5. The upper die
9 is positioned at the top dead center of a pressing machine
above the state shown in the figure.
The upper die 9 starts to descend from the top dead
15 center, and first the lower face of the actuating cam 11 is
contacted to the pivoting plate 8 without interfering the
negative angle former 4 of the cam member 2, which is rotated
clockwise in Fig. 2.
As the upper die 9 continues to descend further, the
20 actuating cam 11 urged externally of the die is moved
laterally or leftward in Fig. 2 to the state shown by the
solid line in the figure of the cam action aqainst the urging
force of the coil spring 17, thereby the work W is formed as
shown by the solid line in Fig. 2 by the negative angle
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former 4 of the cam member 2 pivoted and the negative angle
former 12 of the actuating cam 11.
After the negative angle forming, the upper die 9 starts
to ascend. The actuating cam 11 is urged externally of the
5 die by the coil spring 17, moved rightward in Fig. 2 and
ascended without interfering the work W formed.
Meanwhile, the cam member 2 is rotated counterclockwise
in Fig. 2 to the state shown by the two-dot chain line by the
auto-return device 5, since the actuating cam 11 which has
10 restrained is ascended, so that the work W formed can be
taken out from the lower die 3 without interfering the
negative angle former 4 of the cam member 2.
Second Embodiment
Fig. 8 shows an example of press dies for forming a
15 front-door trim base which is automotive sheet metal parts of
another embodiment.
In the figure, the reference character W indicates a
work, 101 is a groove, 102 is a cam member, 103 is a lower
die, 104 is a negative angle former of the cam member 102,
20 105 is an auto-return device, 106 is a coil spring, 107 is a
push pin, 108 is a pivoting plate, 111 is an actuating cam,
112 is a negative angle former of the actuating cam 111, 115
is a seat, 116 is a positioning pin and 117 is a coil spring.
In the embodiment aforementioned, though the sheet metal
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parts of the automobile has been described, the present
invention is not limited thereto, it is also applicable to
the forming of the other sheet metals, plastics and die
casts.
Third Embodiment
In Fig. 9A, the upper die 9 is positioned at the top
dead center of a press machine. A work W is placed on the
lower die 3.
In Fig. 9B, the upper die g starts to descend from the
top dead center, and first the lower face of the actuating
cam 11 is contacted to the pivoting plate 8 without
interfering the negative angle former 4 of the cam member 2,
which is rotated clockwise.
As the upper die 9 continues to descend further, the
actuating cam 11 urged externally of the die is moved
leftward in Fig. 9C against the urging force of the coil
spring (not shown, numeral 17 of Fig. 6), thereby the work W
is formed as shown in Fig. 9C by negative angle former 4 of
the cam member 2 pivoted and the negative angle former 12 of
the actuating cam 11.
After actuating cam 11, the upper die 9 starts to
ascend. The actuating cam 11 is urged externally of the die
by the coil spring (not shown, numeral 17 of Fig. 6), moved
rightward in Fig. 9D and ascended without interfering the
work W formed. Meanwhile, the cam member 2 is rotated
counterclockwise in Fig. 9D by the auto-return device, since
the actuating cam 11 which has restrained is ascended, so
that the work W formed can be taken out from the lower die 3
without interfering the negative angle former 4 of the cam
member 2.
_ g
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3 ~ 7 4
As described heretofore, in the present invention, a
negative angle forming portion is processed by converting the
linear motion into the rotating motion, whereby the negative
angle forming of the sheet metals, plastics and die casts, in
particular, the forming in the case of large negative angle
portion or the case wherein the sheet metal, plastic and die
cast products are elongated frame having three-dimensional
curved surfaces is possible.
In addition, since the cam member is rotated, it is not
necessary to be divided or deleted to avoid interference,
thus a sufficient strength can be given to the dies to allow
forming with a strong thrust. Accordingly, the distortion
and strain can be eliminated from the products having three-
dimensional curved surfaces, so that no correction is
required after processing, improving the product accuracy
considerably and removing troubles when assembled.
Since the die itself has a sufficient strength, it is
almost not necessary to be repaired as the conventional slide
cam.
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Furthermore, in the prior art slide cam die, a wide area
was required on the side of the lower die where a work is
placed, but in the press die of the present invention, a cam
member is disposed directly on the ~ower cam where the work
5 is placed, so that a small and compact metal die area is
realized, results in a light and inexpensive press die.
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