Note: Descriptions are shown in the official language in which they were submitted.
CA 02529831 2000-11-24
1
METAL CONTAINER WITH THREAD
This application is a division of Canadian Application Serial No.
2,392,234 filed November 24, 2000. The claims of the present application are
directed
to a metal container capable of maintaining a highly airtight condition by way
of a curled
or slightly rounded projection formed at the upper end of a mouth part thereof
which
interacts with a packing laid on a ceiling-surface of a cap which is screwed
on.
However, for the purpose of understanding the invention, including all objects
and
features which are inextricably bound-up in one and the same inventive
concept, the
teachings of those features claimed in the parent Canadian Application Serial
No.
2,392,234 are retained herein.
Accordingly, the retention of any such objects or features which may be
more particularly related to the parent application or a separate divisional
thereof should
not be regarded as rendering the teachings and claiming ambiguous or
inconsistent with
the subject matter defined in the claims of the divisional application
presented herein
when seeking to interpret the scope thereof and the basis in this disclosure
for the claims
recited herein.
The present invention relates to a metal container with thread in which a
mouth part including a threaded part and an upper end of a shoulder part have
an
improved strength. The present invention further relates to a metal container
with thread
capable of maintaining a highly airtight condition.
Conventionally, a metal container with thread, as shown in Fig. 19, is
manufactured by drawing, drawing-and-ironing or impact forming from a metallic
material such as aluminium. An open mouth part of such a metal container is
closed
airtight, as a cap is screwed on a threaded part formed in a periphery of the
cylindrical
mouth part. Fig. 19 is a cross sectional view of a conventional metal
container with
thread. Denoted at 50 is a container main body, and the container main body 50
is
formed by a curled part 51, a mouth part 52 with a threaded part, a tapered
shoulder part
53, a trunk part 54 and a bottom part 55, shown in this order from the top. A
female
screw of a cap 56 and a male screw of the mouth part 52 are fitted with each
other,
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2
whereby the mouth part 52 of the container main body 50 is sealed up. The
symbol 57
denotes packing. In such a container main body 50, as shown in Fig. 20, the
shoulder
part 53 is formed to have a linear cross sectional shape up to its upper end
53a, and the
upper end 53a of the shoulder part 53 is continuous up to a lower end 52a of
the mouth
part.
Meanwhile, a metal container with thread as shown in Fig. 21 is known
and commercially available, where plurality of protruded parts 62 (three in
Fig. 21) are
formed at schematic equal intervals entirely over a shoulder part 61 of a
container main
body 60.
However, as shown in Fig. 20, the container main body 50 shown in Fig.
19 has a problem that the strength of the lower end 52a of the mouth part 52
and the
upper end 53a (area W) of the shoulder part 53 is weak against pressure forces
in a radial
direction and an axial direction (pressing forces P, Q) therefore, the area W
may be
collapsed or buckled during a capping operation to fill content into the
container and fit
a cap to the container automatically using a machine.
With respect to the container main body 60 shown in Fig. 21, a purpose
of forming the plurality of protruded parts 62 entirely over the shoulder part
61 is to
mainly achieve a design effect of the metal container with thread and to
prevent the
shoulder part 61 from getting wrinkled during a necking operation of
manufacturing
steps. Thus, an improvement in strength at the mouth part and the upper edge
of the
shoulder part is not intended here, accordingly no actual enhancement of
strength is
expected.
On the other hand, as shown in Fig. 22, the curled part 51 is formed at the
upper end of the mouth part 52 in the conventional metal container with thread
to thereby
ensure a better strength, safety for a user and sealable effect. In other
words, by means
of an axial clamping force developed as the female screw of the cap 56 is
fitted to the
male screw of the mouth part 52, the packing 57 laid on an inner ceiling
surface of the
cap 56 abuts on a top surface of the curled part 51 formed at the upper end of
the mouth
part 52, whereby an opening at the mouth part 52 is sealed up. A lower end 56a
of the
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3
cap 56 is bent along a bead part (annular groove) 52b formed in the mouth part
52 and
fitted with the upper area of the bead part to its end.
However, since the packing 57 and the ceiling surface of the curled part
51 are in surface contact, such a closing structure has a problem with a
sealing capability
if the curled part 51 has a slight dimensional error and the surface contact
is accordingly
weak. In short, when content develops an internal pressure, the content may
leak out
between the packing 57 and the ceiling surface of the curled part 51.
Particularly, as for
a metal container containing a carbonated beverage such as beer and cola, it
is required
that the metal container is sealed up without fail again after being opened
once, so that
the quality and the internal pressure of the remaining contained drink are
maintained, so
that an insufficient sealing capability becomes a problem.
An attempt to improve a sealing capability by strongly tightening the cap
56 and increasing applied pressure between the packing 57 and the curled part
51 to one
another invites the area W at the upper end of the shoulder part 53 shown in
Fig. 20 to
twist more, and therefore, makes it easier for the area W to be buckled. If
the tightening
force is reduced to prevent such buckling, leakage tends to occur.
On the other hand, in a conventional metal container, an area of the bead
part 52b easily collapses when lower end 56a of the cap 56 is plastically
deformed along
the bead part 52b in the manner as shown in Fig. 22. Further, the cap 56 may
be a screw
cap with preformed thread or a roll-on type cap put on the mouth part 52 to be
pressurized along the male screw of the mouth part to thereby form threads. In
the latter
case, a side wall of the cap 56 is pressed strongly in the radial direction
toward the
inside, and therefore, the threaded part may easily collapse.
In addition, where the metal container shown in Fig. 19 uses a cap such
as a Pilfer Proof cap (PP cap) and a similar Alten cap (also known as a flavor
cap or a
high-lock cap), to be fractured as opened in order to clearly indicate to a
user that the
container has been unopened, the threaded part, the bead part and the like
collapse more
easily and the upper end of the shoulder part buckles more easily, since the
strength of
the cap is high.
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4
The present invention was made in view of the conventional problems
described above, and accordingly, a first object of the present invention is
to provide a
metal container with the threaded part 52 and the lower end 52a of the mouth
part as well
as the upper end 53a (area W) of the shoulder part 53 having an improved
strength in a
radial direction and an axial direction. Further, a second object of the
present invention
is to provide a metal container with thread capable of maintaining a highly
airtight
condition.
A metal container with thread according to the invention is manufactured
by drawing, drawing-and-ironing or impact forming from a metallic material
with
container main body consisting of a mouth part including a threaded part, a
tapered
shoulder part, a trunk part and a bottom part and maintaining a highly
airtight condition
with a cap screwed on, and is characterized in that at least one or more
outwardly
curving smooth annular recessed parts or at least one or more inwardly curving
smooth
annular protruded parts are formed around an upper end of said tapered
shoulder part
widening in a radial direction toward below from a lower end of said mouth
part.
Accordingly to a preferred embodiment, both said annular protruded parts and
annular
recessed parts are formed. Further, a bead part for bending a lower end of
said cap for
engagement may be formed in the vicinity of said lower end of said mouth part.
According to an aspect of the present invention there is provided a metal
container with at least one thread made by drawing, drawing-and-ironing or
impact
forming from a metallic material, having a container main body consisting of a
mouth
part with a threaded part, a tapered shoulder part, a trunk part and a bottom
part and
maintaining a highly airtight condition with a cap screwed on, wherein an
annular
slightly rounded projection with a rounded radius of 0.2 mm to 0.8 mm is
formed at an
upper end of the mouth part so that when the cap is screwed on, the annular
projection
bites into a packing laid on an inner surface of a ceiling surface of the cap
so as to realize
an airtight condition.
According to another aspect of the present invention there is provided a
metal container with at least one thread made by drawing, drawing-and-ironing
or impact
CA 02529831 2000-11-24
forming from a metallic material, having a container main body consisting of a
mouth
part with a threaded part, a tapered shoulder part, a trunk part and a bottom
part and
maintaining a highly airtight condition with a cap screwed on, wherein a
curled part is
5 formed at an upper end of the mouth part with sectional view of a circle,
and a flat
surface is formed at an outer part of the curled part, whereby creating the
outer part of
the curled part has a sectional view of a straight line and an inner part of
the curled part
has a sectional view of an arc and a bent line is formed annularly between the
outer part
and the inner part of the curled part forms.
According to a third aspect of the present invention there is provided
a metal container with at least one thread made by drawing, drawing-and-
ironing or
impact forming from a metallic material, having a container main body
consisting of a
mouth part with a threaded part, a tapered shoulder part, a trunk part and a
bottom part
and maintaining a highly airtight condition with a cap screwed on, wherein a
curled part
is formed at an upper end of the mouth part with sectional view of a circle,
and a flat
surface is formed at an inner part of the said curled part, whereby the inner
part of the
said curled part has a sectional view of a straight line and an outer part of
the said curled
part has a sectional view of an arc and a bent line is formed annularly
between the inner
part and the outer part of the curled part forms.
The container main body may be formed by integral forming so that the
mouth part including the threaded part, the tapered shoulder part, the trunk
part and the
bottom part are integral with each other, or alternatively, the mouth part
including the
threaded part and a tapered neck part may be formed integral with each other
to thereby
form an upper container body, the side wall part and the bottom part may be
formed
integral with each other to thereby form a lower container body, and the upper
container
body and the lower container body may be joined to each other.
According to a fourth aspect of the present invention there is provided a
metal container with at least one thread made by drawing, drawing-and-ironing
or impact
forming from a metallic material, comprising a container main body consisting
of a
mouth part with a threaded part, a tapered shoulder part, a trunk part and a
bottom part;
CA 02529831 2008-05-23
5a
a cap screwed on the mouth part of the container main body; and a packing
housed
inside a ceiling surface of the cap and held between the ceiling surface of
the cap and
an upper end of the mouth part of the container main body; wherein a curled
part is
formed at the upper end of the mouth part and a flat surface part is formed in
a part of
the curled part, whereby an inner part of the curled part has a sectional view
of a
straight line and an outer part of the said curled part has a sectional view
of an arc and
a bent line is formed annularly between the inner part and the outer part of
the curled
part forms, and a side surface part of an upper end of the cap is crimped to
have a
stepped area so that the packing laid on the ceiling surface of the cap abuts
on the flat
surface part of the curled part formed at the upper end of the mouth part.
According to a fifth aspect of the present invention, there is provided a
process for manufacturing a metal container with a thread having an upper
container
body comprising a mouth part and a shoulder part formed integrally and a lower
container body comprising a trunk part and a bottom part formed integrally and
a cap
that maintains a highly airtight condition when screwed on, the process
comprising the
steps of forming a curled part at an upper end of the mouth part, inserting a
core from
the mouth part before forming the flat surface after forming the curled part,
forming
a flat surface by abutting a roll on an outer surface of the curled part.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a front cross sectional view showing a first preferred
embodiment of the present invention;
Fig. 2 is a cross sectional view showing a mouth part and an upper end
of a shoulder part according to the first preferred embodiment of the present
invention;
Fig. 3 is an enlarged cross sectional view showing an area A according
to the first preferred embodiment of the present invention;
Fig. 4 is a cross sectional view showing a mouth part and an upper end
of a shoulder part according to a second preferred embodiment of the present
invention;
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=
5b
Fig. 5 is a cross sectional view showing a mouth part and an upper end
of a shoulder part according to a third preferred embodiment of the present
invention;
Fig. 6 is a cross sectional view showing a mouth part and an upper end
of a shoulder part according to a fourth preferred embodiment of the present
invention;
Fig. 7 is an elevational view showing a crush strength test on a bead part
of a metal container with thread according to the present invention;
Fig. 8 is an elevational view showing a crush strength test on a threaded
part of a metal container with thread according to the present invention;
Fig. 9 is an elevational view showing a buckling strength test on a
shoulder part of a metal container with thread according to the present
invention;
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Fig. 10 is an elevational view showing a metal container with thread
according to the present invention forming a mouth part, a shoulder part, a
side
wall part and a bottom part integrally with each other;
Fig. 11 is an enlarged cross sectional view showing a mouth part having a
threaded part of a metal container with thread according to a fifth preferred
embodiment of the present invention;
Fig. 12 is a cross sectional view showing a condition that a cap is screwed
on the mouth part of the metal container with thread according to the fifth
preferred embodiment of the present invention;
Fig. 13 is a flow chart showing a method of attaching the cap to the
mouth part of the metal container with thread according to the fifth preferred
embodiment of the present invention;
Fig. 14 is a cross sectional view showing a condition that a cap is screwed
on a mouth part of a metal container with thread according to a sixth
preferred
embodiment of the present invention;
Fig. 15 is a cross sectional view showing a condition that a cap is screwed
on a mouth part of a metal container with thread according to a seventh
preferred embodiment of the present invention;
Fig. 16 is a cross sectional view showing a condition that a cap is screwed
on a mouth part of a metal container with thread according to an eighth
preferred embodiment of the present invention;
Fig. 17 is a elevational view showing manufacturing of the metal
container with thread according to the fifth preferred embodiment shown in
Fig.
10;
Fig. 18 is a partial cross sectional elevational view showing a metal
container with thread according to other embodiment of the present invention
which is obtained by bonding an upper container body to a lower container
body;
Fig. 19 is a cross sectional view showing an example of a conventional
metal container with thread;
Fig. 20 is a cross sectional view showing a mouth part and an upper end
CA 02529831 2000-11-24
7
of a shoulder part of the metal container with thread which is shown in Fig.
19;
Fig. 21 is a elevational view showing other example of a conventional
metal container with thread;
Fig. 22 is an enlarged cross sectional view showing a condition that a cap
is screwed on a mouth part of a conventional metal container with thread.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Figs. 1 through 3 show a metal container with thread according to a first
preferred embodiment of the present invention. A container main body 1 of this
container with thread is basically approximately the same as the conventional
one, and as shown in Fig. 1, comprises a cylindrical mouth part 2, a tapered
shoulder part 3 downwardly contiguous from a lower end 2a of the mouth part 2,
a trunk part 11 contiguous from a lower end of the shoulder part, and a bottom
part 12 closing a lower end of the trunk part 11. As clearly shown in Fig. 2,
a
characteristic is that an inwardly curving smooth annular recessed part 4 is
formed in an area around an upper end 3a of the shoulder part 3 (area A) and
below this an outwardly curving smooth annular protruded part 5 is formed
contiguously. A lower portion of the protruded part 5 is linearly continuous,
like
conventional ones. A portion in the vicinity of an upper end of the mouth part
2
has a slightly smaller diameter, and a curled part 13 curled up outwardly is
formed at this upper end. Fig. 3 is a cross sectional view further enlarging
the
area A according to the first preferred embodiment.
The container main body 1 is obtained by drawing, drawing-and-ironing
or impact forming a metallic material, such as aluminium for instance, into a
cylindrical shape with bottom, thereafter forming the shoulder part and the
mouth part by shoulder-drawing, a bead part 2b by rolling, then a threaded
part,
and further the curled part 13 at the upper end of the mouth part by curling
part.
In this embodiment, an upper portion of the container main body 1 including
the
mouth part 2 with the shoulder part 3 and a lower portion including the bottom
part 12 are formed integral with each other.
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8
The diameter of the mouth part 2 is approximately 35 to 40 mm, for
instance, preferably about 37.8 mm, while the diameter of the trunk part 11 is
approximately 60 to 70 mm, preferably about 66.0 to 66.4 mm. The thickness of
a material plate is approximately 0.2 to 0.3 mm, for example, preferably about
0.21 to 0.25 mm. The plate thickness of the mouth part 2 after forming is
approximately 0.3 to 0.4 mm, preferably about 0.31 to 0.35 mm. The angle of
the shoulder part 3 is approximately 25 to 30 degrees with respect to a
perpendicular line. The plate thickness of the shoulder part 3 is around 0.30
to
0.34 mm in the vicinity of the upper end 3a. Meanwhile, the plate thickness of
the trunk part 11 is about 0.11 to 0.15 mm, for instance. The plate thickness
of
the curled part 13 is approximately 0.33 to 0.37 mm.
As shown in Fig. 2, a corrugated male screw 14 is formed by rolling and
otherwise at the mouth part 2. The thread diameter of the male screw 14 is
about 36.9 to 37.5 mm. A skirt part 16 with somewhat larger diameter is
formed in a lower part of the mouth part 2, and the bead part 2b is formed
below
continuously. The bead part 2b is an annular groove and almost trapezoidal in
cross section. The skirt part 16 and an upper wall 17a of the bead part 2b
are,
as described later, for caulking a lower end of a cap to be fractured to open,
such
as a Pilfer Proof cap and an Alten cap (See Fig. 13).
As shown in Fig. 3, a lower wall 17b of the bead part 2b is smoothly
curved to be contiguous to the lower end 2a of the cylindrical mouth part, and
the
annular recessed part 4 is downwardly contiguous from the upper end 3a of the
contiguous shoulder part to the lower end 2a. The recessed part 4, in its
cross
section, preferably has a radius of curvature R of about 0.5 to 5 mm, and more
preferably, approximately 2 to 4 mm. The angle of inclination (i.e., the
degree of
curve) e of a common tangent line K of the recessed part 4 and the protruded
part 5 is preferably about 35 to 60 degrees, and more preferably,
approximately
40 to 50 degrees.
Fig. 4 shows a metal container with thread according to a second
preferred embodiment of the present invention. The container main body 1 of
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9
this metal container is characterized in that one inwardly curving smooth
recessed part 6 is formed in a portion around the upper end 3a of the shoulder
part (area B). The protruded part 5 of Fig. 3 is not formed. The lower wall
17b
of the bead part 2b is contiguous to the upper end of the shoulder part 3
while
remaining inclined, and the recessed part 6 is formed somewhat below this. The
recessed part 6 preferably has approximately the same radius of curvature,
width
and depth as the recessed part 4 according to the first preferred embodiment
shown in Fig 3.
Fig. 5 shows a metal container with thread according to a third preferred
embodiment of the present invention. The container main body 1 of this metal
container is characterized in that one outwardly curving smooth protruded part
7
is formed in a portion around the upper end 3a of the shoulder part 3 (area C)
continuous to the lower end 2a of the mouth part. No recessed part is formed.
The protruded part 7 preferably has approximately the same cross sectional
shape and angle of gradient (i.e., the degree of cuive) as the protruded part
5
according to the first preferred embodiment.
Fig. 6 shows a metal container with thread according to a fourth
preferred embodiment of the present invention. The container main body 1 of
this metal container is characterized in that an inwardly curving smooth
recessed part 8 is formed in a portion around the upper end 3a of the shoulder
part 3 (area D) continuing to the lower end 2a of the mouth part, and
continuously an outwardly cuiving smooth protruded part 9 is formed, and
further continuously an inwardly curving smooth recessed part 10 is formed. In
other words, the two recessed parts 8 and 10 and one protruded part 9 are
formed
alternately in the area D. As another preferred embodiment, two recessed parts
and two protruded parts may be formed alternately (not shown).
Next, an effect of the metal containers with thread above is described.
In the metal containers with thread according to the first to the fourth
preferred
embodiments, since the areas A, B, C and D are each bent to form the recessed
parts and/or the protruded parts, the strength against pressing forces P and Q
CA 02529831 2000-11-24
respectively in a radial direction and an axial direction improves. The radius
of
curvature R and the angle of inclination 8 of the recessed parts and/or the
protruded parts may be larger than the ranges described above. In the case
that
these values are larger, however, the strength against the pressing force P in
the
5 radial direction is stronger, while the strength against the pressing force
Q in the
axial direction is weaker. Hence, to improve in strength against both the
pressing forces P and Q, the recessed parts described above preferably have
the
radius of cuivature R of about 0.5 to 5 mm and the angle of 6 of about 35 to
60
degrees.
10 [Embodiment]
The following describes test results comparing the strength of the mouth
part and the upper end of the shoulder part between the metal container with
thread compizsing the recessed part 4 and the protruded part 5 (Embodiment)
according to the first preferred embodiment of the present invention and a
conventional metal container with thread not comprising a recessed part or a
protruded part (Comparison). Fig. 7 shows a test for measuring a crush
condition of the bead part 2b of the mouth part 2 when pressurized with a
pressing force Fl from above, Fig 8 shows a test for measuiing a crush
condition
of the threaded part when pressurized the mouth part 2 from above with a
pressing force F2, and Fig. 9 shows a test for measuring a buckling strength
when pressurized the upper end of the mouth 2 from above in the axial
direction
with a pressing force F3.
[Test Condition]
The outer diameter of the container: 66 mmo. The height of the
container: 166 mm. The outer diameter of the mouth part: 37.8mmo. The
thickness of the threaded part and the bead part: 0.32 mm. The thickness of
the
lower end of the shoulder part: 0.2 mm. The thickness of the trunk of the
container: 0.15 mm. The test results are as shown in Table 1.
[Table 1]
The number of testing n = 2
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11
Crush Strength of Crush Strength of Buckling Strength of
Bead Part (N) Threaded Part (N) Shoulder Part (N)
Comparison 113 137 1451
Embodiment 167 142 1657
From the test results above, it is found that with respect to the metal
containers with thread according to the present invention, the crush strength
of
the bead part improves 47.8 %, the crush strength of the threaded part
improves
3.6 % and the buckling strength of the shoulder part improves 14.2 %.
As described above, the present invention has an effect to improve the
strength in an area around the mouth part of the metal container with thread,
and particularly in an area from the lower end of the threaded part to the
upper
end of the shoulder part.
Next, a second aspect of the present invention is described with reference
to the associated drawings. Figs. 10 to 12 show a fifth preferred embodiment
of
the present invention, and a cap 18 to cover the mouth part 2 is illustrated
in an
upper portion of the container main body 1 therein. The cap 18 has a
cylindrical
shape with bottom, and a female screw 19 to engage with the threaded part of
the
mouth part 2 is formed in a peripheral wall. The cap 18 is a so-called Pilfer
Proof cap. Other caps to be broken as opened, such as an Alten cap, may be
used
instead.
A characteristic of the fifth preferred embodiment is that an annular
projection 13a is formed at the upper end of the mouth part 2 of the container
main body 1 as shown in Figs. 11 and 12. Other configurations are
substantially
the same as those shown in Fig. 1, and therefore, the same portions is denoted
at
the same reference symbols and is not described. In order to form the
projection
13a at the outer upper end of the mouth part 2, first, the curled part 13 in
circular-shaped cross section is formed by a normal method, such as press work
using a curling die, at the upper end of the mouth part 2, a core 22 is
inserted
inside the container main body 1 as shown in Fig. 17, and then an outer
circumferential surface of the curled part 13 is crushed with a roll 23
abutting on
CA 02529831 2000-11-24
12
the curled part 13 from the outward side to thereby form a flat surface part
13b
on the cylindrical surface approximately in parallel to the central axis of
the
container main body 1. As a result, as shown in Fig. 11, the projection 13a is
created at an intersection of an inner circumferential surface 13c and the
flat
surface part 13b of the curled part 13 as it originally has a circular shape
in cross
section, i.e., along a bent line outside the upper end. The projection 13a is
loosely cuived (over about 0.2 to 0.8 mm).
In order to attach the cap 18 of the Pilfer Proof type to the container main
body 1 manufactured in this manner, first, as denoted at a capping step S 1
shown
in Fig. 13, the cap 18 is screwed on the mouth part 2 of the container main
body 1.
In this condition, the upper end at the outer periphery of the cap 18 is
cylindrical
without any stepped area created. Meanwhile, the lower end remains directly
downward. Further, in this condition, there is a gap between the flat surface
part 13b of the curled part 13 and the inner circumferential surface of the
cap 18,
and an outer circumferential part 24a of packing 24 fit inside a ceiling
surface of
the cap 18 expands sidewise. This however realizes a high sealable effect,
since
the projection 13a bites into the packing 24.
Following this, as denoted at a caulking step S2 shown in Fig. 13, an
upper end 18a at the outer periphery of the cap 18 is pressurized inwardly in
the
radial direction, to thereby form an annular stepped part. This makes the
outer
circumferential part 24a of packing 24 bent downward and held between the flat
surface part 13b and an inner surface of the annular stepped part. This
further
enhances the sealable effect. Further, a lower end 18b of the cap is bent
inwardly and pressed against the upper wall 17a of the bead part 2b. The cap
18 is consequently fit so as not to be removed unless broken.
According to a sixth preferred embodiment shown in Fig. 14, a curled part
15 is applied crushing so as to be inclined at a certain angle with respect to
the
central axis of the container main body 1, and a flat surface part 15b is
accordingly created. At an intersection of the flat surface part 15b and the
curled part 15, approximately right above the curled part 15, a projection 15a
is
CA 02529831 2000-11-24
13
formed. The projection 15a is loosely curved (with a radius of about 0.2 to
0.8
mm).
According to a seventh preferred embodiment shown in Fig. 15, after
forming a flat surface part 25b with a cylindrical surface at an outer
periphery of
the curled part 25 to be approximately parallel to the central axis of the
container
main body 1, a flat surface part 25c inclined at a certain angle is further
formed
on the flat surface part 25b. Due to this, a projection 25a is created at an
intersection of the flat surface part 25c and the curled part 25,
approximately
right above the curled part 25. The projection 25a is loosely curved (with a
radius of about 0.2 to 0.8 mm). The inclined flat surface part 25c described
above has a three-dimensional conical shape in reality.
Further, according to an eighth preferred embodiment shown in Fig. 16,
crushing applied to a curled part 35 is executed on the opposite side of the
first
preferred embodiment, namely, the inward side of the container main body 1, so
that a flat suid'ace part 35b is formed on the inward side of the curled part
35.
Hence, a projection 35a is created at an inward upper end. The projection 35a
is
loosely curved (with a radius of about 0.2 to 0.8 mm).
In any one of the preferred embodiments described above, the container
main body 1 is formed as integrated one unit. However, the present invention
is
not limited to this. The container main body can be created by joining two or
more components. The container main body 1 of the metal container with
thread shown in Fig. 18 is manufactured as separate units, an upper container
body la compzzsing the mouth part 2 and the shoulder part 3 formed integral
with each other and a lower container body lb comprising the trunk part 11 and
the bottom part 12 formed integral with each other. A cylindrical joint part
3b
for capping an upper end of the trunk part 11 extends at the lower end of the
shoulder part 3. After forming the respective components, the joint part 3b is
put on the upper end of the trunk part 11 and adhered with an adhesive or the
like, whereby the container main body 1 is manufactured as one integrated
unit.
As for the upper container body la, typically, after forming the upper
container
CA 02529831 2000-11-24
14
body la into an upside-down cylindrical shape with bottom, the shoulder part 3
and the mouth part 2 are drawn, the upper end of the mouth part is then
punched through to create an opening, and the bead part, the threaded part and
the curled part 13 are thereafter formed in a manner similar to the above
described. Hence, the mouth part 2 is relatively thick and has a high
strength.
Forming of the annular projection at the upper end of the curled part 13 and a
method of the forming, etc. are the same as in the preferred embodiments
described above.
Next, an effect of the seal structure above is described. In the metal
containers with thread described above, since the curled parts 13, 15, 25 and
35
are created and processed to form the respective flat surface parts 13b, 15b,
25b,
25c and 35b as well as the projections 13a, 15a, 25a and 35a at the
intersections
of the curled parts and the flat surface parts, when the cap 18 is screwed on
the
threaded part of the mouth part 2 of the container main body 1, the
projections
13a, 15a, 25a and 35a bite and fit into the packing 24 laid inside the ceiling
surface of the cap 18. As a result, the opening of the mouth part 2 of the
container main body 1 is sealed up without fail. In other words, at the
positions
where the projections 13a, 15a, 25a and 35a bite into the packing 24, the
projections 13a, 15a, 25a, 35a reliably seive as annular seal points. As the
cap
18 is screwed and clamps, the mouth part 2 of the container main body 1 is
sealed up tightly. Hence, even if content is a beverage with an internal
pressure,
such as beer and cola, etc. it is possible to maintain the quality and the
internal
pressure of the leftover.
As described above, the present invention has an effect to prevent leakage
of content at the mouth part and maintain the quality and the internal
pressure
of a leftover beverage without fail. In addition, since a highly airtight
condition
is ensured, the cap need not be tightened too strong during a capping
operation,
so that it is possible to prevent the shoulder part and the like of the
container
main body from buckling and deformation.
