Note: Descriptions are shown in the official language in which they were submitted.
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Description
EASY OPEN CAN END WITH HIGH PRESSURE VENTING
Technical Field
[0001] This invention relates broadly to the field of convenience closures
for full-open type
can ends. More specifically, this invention relates to convenience closures
for full-
open type can ends which are suitable for use in pressurised food can
applications.
Further aspects of the invention relate to a method and tooling assembly for
making
such a convenience closure.
Background Art
[0002] One form of self-opening can which is in wide use is the so called
full-open can, in
which a peripheral score, generally circular in configuration, is formed in
the end panel
at or adjacent to the periphery thereof to permit its complete removal.
[0003] Full-open type cans are to be distinguished from those self-opening
cans which have
a comparatively small removable section which, when opened, provide a com-
paratively small hole for dispensing the product. The latter type of can end
is only ap-
propriate for packaging soda, beer, or other liquids. Full-open type cans, on
the other
hand, are suitable for packaging solid products such as candy, nuts, meats, or
ground
coffee.
[0004] A conventional full-open type can end of the type disclosed in U.S.
Patent 5,232,114
to Zysset is depicted in FIGURE 1. Can end 10 conventionally includes an end
panel
12 and an edge-curled peripheral flange 14 that is adapted to be interfolded
with an
end flange of a can body. At or adjacent to the periphery of the end panel 12
is a
peripheral score 16 which is indented into the end panel 12 and defines a
fixed can end
portion 18 and a removable portion or panel 20. A gripping tab 22 is mounted
to the
end panel 12 by means of a rivet formation 24.
[0005] The gripping tab 22 is positioned close enough to the peripheral
score 16 so that
when its inner end is rocked upwardly to cause its outer end to move
downwardly and
exert a downward force on the end panel 12 at or near the peripheral score 16,
a
portion of the end panel 12 is bent downwardly to initiate rupture of the
peripheral
score 16. Thereafter, an upward and backward pull on the gripping tab 22 by
the user
induces tearing of the metal in the peripheral score 16 on both sides of the
area of
initial rupture to complete detachment from the can of the removable portion
or panel
20 of the end panel 12.
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[0006] It is also known within the prior art to employ a vent score behind
the rivet formation
24 toward the centre of the end panel 12 in order to relieve internal pressure
or vacuum
that exists within the container, and thereby avoid implosion or explosion as
the
container is opened by pivoting of the gripping tab 22 about the rivet
formation 24.
The most frequently used shape for the vent score is curved like a man's
moustache
and therefore these scores are generally known as "moustache scores."
[0007] For the aforesaid purposes and to promote flexibility and to provide
a hinge point for
the tab 22 when it is lifted, a moustache score 34 may be formed in the end
panel 12,
as is illustrated in FIG. 1. Moustache score 34 typically has an inner portion
36 that is
defined on a raised area 26 of rivet formation 24 having an outer edge 27, and
at least
one outer portion 38 that is defined on the outer surface of end panel 12.
Raised area
26 includes an oval shaped first operation butble 40, which is elongated along
an axis
which is a chord perpendicular to a radius of end panel 12. Raised area 26
further
includes a second operation butble 30, which is defined centrally with respect
to the
first operation bible 40.
[0008] The inner portion 36 of moustache score 34 may be curved about the
radial inner
periphery of the second operation butble 30. The outer portions 38 of the
moustache
score 34 would typically be shaped so as to flare outwardly from the
respective inner
portions 36, and would typically end up at their extreme outer ends to be
substantially
parallel or slightly curved away from the peripheral score 16.
[0009] Although conventional moustache scores, such as the one that is
described above, are
generally effective in preventing violent explosions or implosions during the
opening
of containers that are moderately pressurised or underpressurised, they tend
to be in-
effective in preventing explosions during the opening of highly pressurised
containers.
A highly pressurised container for the purposes of this document is a
container that is
pressurised to at least 25 pounds per square inch over ambient pressure
conditions.
[0010] A need exists for an improved easy open can end that can be used
with highly
pressurised containers and that is capable of effectively reducing the
likelihood of a
violent explosion or implosion occurring when such a highly pressurised
container is
opened.
[0011] Accordingly, it is an object of the invention to provide an improved
easy open can
end that can be used with highly pressurised containers and that is capable of
ef-
fectively reducing the likelihood of a violent explosion or implosion
occurring when
such a highly pressurised container is opened.
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Disclosure of Invention
[0012] In order to achieve the above and other objects of the invention, a
full-open con-
venience closure which is adapted for sealing an end of a can according to a
first
aspect of the invention comprises an end panel, a peripheral score in the end
panel, the
peripheral score defining fixed and removable portions of the end panel, a tab
having a
nose portion for exerting a downwards force on the end panel in an area
proximate to
the peripheral score, a rivet formation for securing the tab to the end panel,
char-
acterised in that the closure further comprises a flex line score defined in
the end panel
and located adjacent to the rivet formation.
[0013] In a second aspect of the invention there is provided a method of
making a con-
venience closure, comprising:
providing an end panel;
forming a moustache score in the end panel;
characterised in that the method further comprises forming a flex line score
in the
end panel adjacent to the moustache score.
[0014] In a third aspect of the invention there is provided a tooling
assembly for forming an
end panel of a full-open convenience closure, comprising:
a first forming tool for forming a top surface of an end panel for an easy
open can
end, said first forming tool comprising:
a first tool surface that is constructed and arranged to form a moustache
score in the
end panel;
a second tool surface that is constructed and arranged to form a flex line
score in the
end panel that is in a predetermined relationship to the moustache score;
the tooling assembly further comprising:
a second forming tool that is constructed and arranged to work together with
the first
forming tool; and
a press assembly for driving at least one of the first and second forming
tools.
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[0014a] According to one aspect of the present invention, there is
provided a full-open
convenience closure for sealing an end of a can, comprising an end panel, a
peripheral score
in the end panel, the peripheral score defining fixed and removable portions
of the end panel,
a tab having a nose portion for exerting a downwards force on the end panel in
an area
proximate to the peripheral score, a rivet formation for securing the tab to
the end panel, the
closure further comprising a flex line score defined in the end panel and
located adjacent to
the rivet formation, which flex score line has a first portion that is located
on a first side of the
rivet formation and a second portion that is located on a second, opposite
side of the rivet
formation, and a moustache score defined in the end panel which includes a
central portion
that is positioned radially inwardly on the end panel relative to the rivet
formation and is
curved about the rivet formation in such a manner that a concave side of the
central portion
faces the rivet formation and includes first and second end portions; wherein
at least two
break line scores are defined in the end panel to provide a pre-weakened
tearing path between
the moustache score and the flex line score.
[0014b] According to another aspect of the present invention, there is
provided a
method of making the convenience closure as described herein the method
comprising:
providing an end panel; forming a moustache score in the end panel; forming a
flex line score
in the end panel adjacent to the moustache score; forming at least two break
line scores
between the moustache score and the flex line score.
[0014c] According to still another aspect of the present invention, there
is provided a
tooling assembly for forming the end panel of a full-open convenience closure
as described
herein, the tooling assembly comprising: a first forming tool for forming a
top surface of an
end panel for an easy open can end, said first forming tool comprising: a
first tool surface that
is constructed and arranged to form a moustache score in the end panel; a
second tool surface
that is constructed and arranged to form a flex line score in the end panel
that is in a
predetermined relationship to the moustache score; the tooling assembly
further comprising: a
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second forming tool that is constructed and arranged to work together with the
first forming
tool; and a press assembly for driving at least one of the first and second
forming tools;
wherein the first forming tool further comprises third and fourth tool
surfaces for forming first
and second break line scores.
[0014d] According to yet another aspect of the present invention, there is
provided a
full open type of convenience closure which is adapted for sealing an end of a
can,
comprising: an end panel; a peripheral score defined in said end panel, said
peripheral score
defining fixed and removable portions of said end panel; a tab having a nose
portion for
exerting a downward force on said end panel in an area that is proximate to
said peripheral
score; a rivet formation for securing said tab to said end panel; a mustache
score defined in
said end panel, said mustache score including a central portion that is
positioned radially
inwardly on said end panel relative to said rivet formation and is curved
about said rivet
formation and first and second end portions that are curved away from said
rivet formation;
wherein most of the total length of the first and second end portions are
substantially curved
away from a nearest portion of said peripheral score, wherein the first and
second end portions
comprise a majority of the mustache score; and further wherein the mustache
score is
substantially arcuate throughout; a flex line score defined in said end panel
adjacent to said
rivet formation and a pair of break line scores, each of said break line
scores are positioned
between said mustache score and said flex line score.
[0014e] According to a further aspect of the present invention, there is
provided a full-
open type of convenience closure which is adapted for sealing an end of a can,
comprising: an
end panel; a peripheral score defined in said end panel, said peripheral score
defining fixed
and removable portions of said end panel; a tab having a nose portion for
exerting a
downward force on said end panel in an area that is proximate to said
peripheral score; a rivet
formation for securing said tab to said end panel; a mustache score defined in
said end panel,
said mustache score including a central portion that is positioned radially
inwardly on said end
panel relative to said rivet formation and is curved with a concave side of
curvature facing
said rivet formation; a first end portion that is continuous with a first end
of said central
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portion, wherein most of the total length of said first end portion is curved
away from a
nearest portion of said peripheral score, with a convex side of curvature
facing said nearest
portion of said peripheral score; a second end portion that is continuous with
a second end of
said central portion, wherein most of the total length of said second end
portion is curved
away from a nearest portion of said peripheral score, with a convex side of
curvature facing
said nearest portion of said peripheral score; and wherein the first and
second end portions
comprise a majority of the mustache score and further wherein the mustache
score is
substantially arcuate throughout; a flex line score defined in said end panel
adjacent to said
rivet formation; and a pair of break line scores, each of said break line
scores are positioned
between said mustache score and said flex line score.
[0014f] According to yet a further aspect of the present invention,
there is provided a
full open type of convenience closure which is adapted for sealing an end of a
can,
comprising: an end panel; a peripheral score defined in said end panel, said
peripheral score
defining fixed and removable portions of said end panel; a tab having a nose
portion for
exerting a downward force on said end panel in an area that is proximate to
said peripheral
score; a rivet formation for securing said tab to said end panel; a mustache
score defined in the
end panel, the mustache score including a central portion that is positioned
radially inwardly
on the end panel relative to the rivet formation and is curved about the rivet
formation, and the
mustache score including first and second end portions that are curved away
from the rivet
formation; a flex line score defined in said end panel adjacent to said rivet
formation, said flex
line score having a first linear portion and a second curved portion, wherein
said flex line
score is disposed separately from said mustache score; and further comprising
a break line
score defined in said end panel, wherein the break line score is located
between the mustache
score and the flex line score, and said break line score is perpendicularly
connected to both the
mustache score and the flex line score.
[0014g] According to still a further aspect of the present invention,
there is provided a
method of making a convenience closure, comprising: providing an end panel;
forming a
mustache score in said end panel; and forming a flex line score in said end
panel adjacent to
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said mustache score; further comprising forming a rivet formation in said end
panel, and
wherein said flex line score is adjacent to said rivet formation; wherein said
mustache score
includes a central portion that is positioned radially inwardly on said end
panel relative to said
rivet formation and is curved about said rivet formation and further has first
and second end
portions that are curved away from said rivet formation, wherein said end
panel has an
diametric axis of symmetry that intersects a center point of said central
portion of said
mustache score and said rivet formation has a center point, and wherein a
transition between
said central portion and said first end portion is located at a transitional
angle from said
diametric axis of symmetry as measured from said center point, and wherein
said transitional
angle is substantially within a range of about 45 degrees to about 60 degrees.
[0014h] According to another aspect of the present invention, there is
provided a
method of making a convenience closure, comprising: providing an end panel;
forming a
mustache score in said end panel; and forming a flex line score in said end
panel adjacent to
said mustache score; further comprising forming a rivet formation in said end
panel, and
wherein said flex line score is adjacent to said rivet formation; wherein said
mustache score
includes a central portion that is positioned radially inwardly on said end
panel relative to said
rivet formation and is curved about said rivet formation and further has first
and second end
portions that are curved away from said rivet formation, wherein said first
end portion has a
substantially constant radius of curvature.
[0014i] According to yet another aspect of the present invention, there is
provided a
method of making a convenience closure, comprising: providing an end panel;
forming a
mustache score in said end panel; and forming a flex line score in said end
panel adjacent to
said mustache score; further comprising forming at least one break line score
that is
positioned between said mustache score and said flex line score; wherein said
at least one
break line score is formed to comprise a pair of break line scores, each of
said break line
scores being positioned between said mustache score and said flex line score,
wherein said
break line score is formed to have a residual thickness that is greater than a
residual thickness
of said flex line score.
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[0014j] According to another aspect of the present invention, there is
provided a
method of making a convenience closure, comprising: providing an end panel;
forming a
mustache score in said end panel; and forming a flex line score in said end
panel adjacent to
said mustache score; further comprising forming at least one break line score
that is
positioned between said mustache score and said flex line score; wherein said
at least one
break line score is formed to comprise a pair of break line scores, each of
said break line
scores being positioned between said mustache score and said flex line score,
wherein said
break line score has a residual thickness that is greater than a residual
thickness of said
mustache score.
[0014k] According to still another aspect of the present invention, there
is provided a
method of making a convenience closure, comprising: providing an end panel;
forming a
curved mustache score in said end panel; forming a flex line score in said end
panel adjacent
to said mustache score, said flex line score having a first linear portion and
a first curved
portion; forming a first break line score extending between and contacting
both the first linear
portion and the mustache score, further wherein the first break line score is
perpendicular to
the first linear portion; and wherein the mustache score is located more
radially inwardly on
the end panel than said first curved portion.
[00141] According to yet another aspect of the present invention,
there is provided a
method of making a convenience closure, comprising: providing an end panel;
forming a rivet
formation in said end panel; forming a mustache score in said end panel,
wherein said
mustache score has a central portion positioned radially inwardly on the end
panel relative to
the rivet formation; and forming a flex line score in said end panel adjacent
to said rivet
formation, said flex line score having a first linear portion and a first
curved portion; and
forming a first break line score extending between and contacting both the
first linear portion
and the mustache score, further wherein the first break line score is score
perpendicular to the
first linear portion.
[0014m] According to a further aspect of the present invention, there
is provided a
tooling assembly for forming an end panel of a full open easy open can end,
comprising: a
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first forming tool shaped to form a top surface of said end panel for said
easy open can end,
wherein said first forming tool has a diametric axis of symmetry, said first
forming tool
comprising: a first tool surface that is mustache score shaped and is
constructed and arranged
to form said mustache score in said end panel; wherein the first tool surface
has a central
portion having a center point, a first end portion located adjacent the
central portion, and a
second end portion located adjacent the central portion and wherein the first
end portion and
the second end portion are equidistant in length; a second tool surface that
is constructed and
arranged to form a first linear flex line score in said end panel; wherein
said second tool
surface comprises a linear first portion shaped to form said first flex line
score, wherein the
linear first portion is located on a first side of a rivet formation area on
the first forming tool,
and a linear second portion shaped to form the linear flex line score, wherein
the linear second
portion is located on a second side of the rivet formation area on the first
forming tool,
wherein the first linear portion and the second linear portion are
substantially perpendicular to
the diametric axis of symmetry; a second forming tool that is constructed and
arranged to
work together with said first forming tool; and a press assembly for driving
at least one of said
first and second forming tools.
[0014n] According to yet a further aspect of the present invention,
there is provided a
tooling assembly for forming an end panel of a full open easy open can end,
comprising: a
first forming tool for forming a top surface of said end panel for said easy
open can end, said
first forming tool comprising: a first tool surface that is mustache score
shaped and that is
constructed and arranged to form a mustache score in said end panel, wherein
the first tool
surface has a central portion having a center point and a first end portion
located adjacent the
central portion, and wherein said central portion of the first tool surface is
positioned radially
inwardly on said first forming tool relative to a rivet formation area and is
curved with a
concave side of curvature facing a rivet formation area; wherein the first end
portion is
continuous with a first end of said central portion, wherein most of the total
length of said first
end portion is curved away from a nearest portion of an edge of the first tool
surface, with a
convex side of curvature facing said nearest portion of said edge of the first
tool surface; and
wherein the first tool surface further comprises a second end portion that is
continuous with a
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second end of said central portion, wherein most of the total length of said
second end portion
is curved away from a nearest portion of said edge of the first tool surface,
with a convex side
of curvature facing said nearest portion of said edge of the first tool
surface; a second tool
surface shaped to form a first flex line score; wherein said second tool
surface comprises a
linear first portion shaped to form said first flex line score, wherein the
linear first portion is
located on a first side of a rivet formation area on the first forming tool,
and a linear second
portion shaped to form the linear flex line score, wherein the linear second
portion is located
on a second side of the rivet formation area on the first forming tool,
wherein the first linear
portion and the second linear portion are substantially perpendicular to a
diametric axis of
symmetry; a second forming tool that is constructed and arranged to work
together with said
first forming tool; and a press assembly for driving at least one of said
first and second
forming tools.
[0014o] According to still another aspect of the present invention,
there is provided a
tooling assembly for forming an end panel of a full open easy open can end,
comprising: a
first forming tool for forming a top surface of an end panel for an easy open
can end, wherein
said first forming tool has a diametric axis of symmetry, said first forming
tool comprising: a
first tool surface that is mustache score shaped, wherein the diametric axis
of symmetry
intersects a center point of the first tool surface, wherein the first tool
surface is symmetric
about the diametric axis of symmetry; a second tool surface having a first
portion that is
located on a first side of a rivet formation and a second portion that is
located on a second,
opposite side of the rivet formation, wherein the first portion has a first
linear portion and a
curved portion; wherein the second tool surface forms a flex line score in
said end panel,
wherein said first linear portion of said second tool surface is substantially
perpendicular to
said diametric axis of symmetry; and a third tool surface having a second
linear portion
perpendicular to the first linear portion of the first tool surface; a second
forming tool that
works together with said first forming tool; and a press assembly for driving
at least one of
said first and second forming tools.
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[0014p] According to another aspect of the present invention, there is
provided an end
panel tooling assembly for forming an end panel of a full open easy open can
end, comprising:
a first forming tool, wherein said first forming tool has a diametric axis of
symmetry,
comprising; a first tool surface shaped to a mustache score, wherein the
diametric axis of
symmetry intersects a center point of the first tool surface, wherein the
first tool surface is
symmetric about the diametric axis of symmetry; a second tool surface further
comprising a
first linear portion and a curved portion, wherein said first linear portion
of said second tool
surface is substantially perpendicular to said diametric axis of symmetry; a
third tool surface
comprising a second linear portion perpendicular to said first linear portion;
a second forming
tool that is constructed and arranged to work together with said first forming
tool; and a press
assembly for driving at least one of said first and second forming tools.
[0015] These and various other advantages and features of novelty
that characterise
the invention are pointed out with particularity in the claims annexed hereto
and forming a
part hereof. However, for a better understanding of the invention, its
advantages, and the
objects obtained by its use, reference should be made to the drawings which
form a further
part hereof, and to the accompanying descriptive matter, in which there is
illustrated and
described a preferred embodiment of the invention.
Brief Description of Drawings
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[0016] FIGURE 1 is a diagrammatical view of a previously known easy open
can end con-
figuration;
[0017] FIGURE 2 is a perspective view of an easy open can end that is
constructed
according to a preferred embodiment of the invention;
[0018] FIGURE 3 is a fragmentary cross-sectional view of the easy open can
end that is
depicted in FIGURE 2;
[0019] FIGURE 4 is a fragmentary cross-sectional view of a press assembly
that is
preferably used in accordance with a preferred embodiment of the invention;
[0020] FIGURE 5 is a diagrammatical depiction of an opening score pattern
and a forming
tool according to a preferred embodiment of the invention;
[0021] FIGURE 6 is a diagrammatical depiction of an opening score pattern
and a forming
tool according to a modified embodiment of the invention;
[0022] FIGURE 7 is a diagrammatical depiction of the opening score pattern
that is shown
in FIGURE 5;
[0023] FIGURE 8 indicates that the seven forming operations in a preferred
method of
forming an easy open can end according to a preferred embodiment of the
invention;
[0024] FIGURE 9 is a diagrammatical depiction of an improved opening score
pattern and a
forming tool according to the preferred embodiment of the invention; and
[0025] FIGURE 10 is a diagrammatical depiction of the opening score pattern
that is shown
in FIGURE 9.
Mode(s) for Carrying Out the Invention
[0026] Referring now to the drawings, wherein like reference numerals
designate cor-
responding structure throughout the views, and referring in particular to
FIGURES 2
and 3, a full-open convenience closure or easy open can end 50 that is
constructed
according to a preferred embodiment of the invention includes an end panel 52
that has
pictorial opening instructions 54 embossed thereon. As is conventional, a
peripheral
score 72 has been formed in the end panel 52 and defines a fixed portion 74 of
the end
panel 52 and a removable portion 76 of the end panel 52. A finger well 56 is
defined in
an upper surface of the end panel 52.
[0027] The full-open convenience closure 50 further includes a
circumferentially extending
end curl or seaming panel 58 that is constructed and arranged to be secured to
a
container using a dotble seaming process. It also includes a tab 60 that has a
main
body portion 62 including a nose portion 63 that is constructed and arranged
to exert a
downward force on the end panel 52 in an area that is proximate to the
peripheral score
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72 when a lifting ring 64 of the tab 60 is lifted by a consumer. A rivet
formation 66
secures the tab 60 to the end panel 52. Convenience closure 50 further
preferably
includes a double fold 68 that is defined in the end panel 52 adjacent to the
peripheral
score 72 in order to provide cut protection for a consumer.
[0028] According to one particularly advantageous feature of the invention,
a plurality of
opening scores 70 are preferably defined in the end panel 52 in an area that
is generally
proximate to the location of the rivet formation 66. The opening scores 70
preferably
include a moustache score 78, a flex line score 80 and a pair of break line
scores 98,
100, which are best shown in FIGURE 7. Although in the preferred embodiment
the
end panel 52 has all of these scores defined therein, it should be understood
that in al-
ternative embodiments of the invention the moustache score 78 could be
provided with
a flex line score, with or without a break line score.
[0029] FIGURE 7 provides a more detailed view of the opening scores 70 in
the preferred
embodiment. As FIGURE 7 shows, the moustache score 78 preferably includes a
central portion 84 that is positioned radially inwardly on the end panel 52
relative to
the rivet formation 66 and is curved about the rivet formation 66 in such a
manner that
a concave side of the central portion 84 faces the rivet formation 66. The
curvature of
the central portion 84 is preferably a constant radius of curvature.
[0030] Moustache score 78 further preferably includes first and second end
portions 86, 88
that are preferably symmetric with respect to each other about a diametric
axis of
symmetry 82 that extends through the centre 90 of the rivet formation 66. Each
of the
first and second end portions 86, 88 preferably include a convex side of
curvature that
faces the nearest portions of the peripheral score 72.
[0031] Each of the first and second end portions 86, 88 preferably have a
constant radius of
curvature R1 that preferably extends along an arc section that is at least
about 1500
.
The constant radius of curvature R1 is preferably substantially within a range
of about
0.07 inches to about 0.2 inches. The distal ends of the first and second end
portions 86,
88 in the preferred embodiment point away from the nearest portion of the
peripheral
score 72, and a tangent line extending through the distal ends (i.e.
tangential to the
distal ends) would preferably be substantially perpendicular to a tangent line
of the
peripheral score 72 at a location where the first tangent line would intersect
the
peripheral score 72.
[0032] Preferably, a transition location 92 between the central portion 84
and the first end
portion 86 is located at a transitional angle a from the diametric axis of
symmetry 82
that is preferably substantially within a range of about 45 to about 60 .
More
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preferably, this angle is substantially within a range of about 50 to about
55 .
[0033] The flex line score 80 preferably has a first portion 94 that is
located on a first side of
the rivet formation 66 and a second portion 96 that is located on a second,
opposite
side of the rivet formation 66. The first and second portions 94, 96 of the
flex line
score 80 are preferably aligned and symmetric with respect to each other and
are both
linear. The flex line score 80 and its components 94, 96 are preferably
substantially
perpendicular with respect to the diametric axis of symmetry 82.
[0034] The flex line score 80 preferably has a residual thickness (i.e. a
thickness that
remains in the end panel 52 at the location of the score line 80) that is
substantially the
same as a residual thickness of the moustache score 78. The flex line score 80
further
preferably has a residual thickness that is within a range of about 25% to
about 40% of
a thickness of the end panel 52. More preferably, the flex line score 80 has a
residual
thickness that is substantially within a range of about 30% to about 35% of
the
thickness of the end panel 52.
[0035] The moustache score 78 has a residual thickness that is preferably
substantially
within a range of about 25% to about 40% of the thickness of the end panel 52.
More
preferably, the moustache score 78 has a residual thickness that is
substantially within
a range of about 30% to about 35% of the thickness of the end panel 52. The
moustache score 78 preferably has a residual thickness that is no greater than
about
0.0045 inches, and more preferably no greater than about 0.0035 inches.
[0036] As FIGURE 7 shows, the portions of the moustache score 78 that most
closely
approach the flex line score 80 present a convex side of curvature that faces
the flex
line score 80.
[0037] As seen in FIGURE 7, in the preferred embodiment of the invention a
pair of break
line scores 98, 100 are defined in the end panel 52 in order to provide a pre-
weakened
tearing path between the moustache score 78 and the flex line score 80 that is
utilised
by the convenience closure 50 during the preliminary stages of opening. The
break line
scores 98, 100 are positioned between the moustache score 78 and the flex line
score
80. Each of the break line scores 98, 100 are preferably substantially
perpendicular to
the flex line score 80 and are aligned with locations on the respective first
and second
end portions 86, 88 of the moustache score 78 that most closely approach the
flex line
score 80.
[0038] The break line scores 98, 100 are preferably substantially
perpendicular with respect
to tangent lines that would pass through the locations on the respective first
and second
end portions 86, 88 of the moustache score 78 that most closely approach the
flex line
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score 80. The break line scores 98, 100 preferably have a residual thickness
that is
greater than a residual thickness of the flex score line 80 and that is
greater than a
residual thickness of the moustache score 78. The residual thickness of the
break line
scores 98, 100 is preferably substantially within a range of about 30% to
about 95% of
the thickness of the end panel 52, with a more preferred range of about 50% to
about
80% of the thickness of the end panel 52.
[0039] When the convenience closure 50 is used in conjunction with a can
body to package
contents under high pressure (i.e. over 20 psi), it may be opened by a
consumer by
gripping the lifting tab 60 and pulling the lift ring 64 upwardly.
[0040] As the gripping tab 60 pivots about the rivet formation 66, the nose
portion 63 will
move downwardly and exert a downward force on the end panel 52 at or near the
peripheral score 72. Before the end panel 52 is bent downwardly enough to
initiate
rupture of the peripheral score 74 however, sufficient tension is formed in
the end
panel 52 in the area near the central portion 84 of the moustache score 78 to
cause a
rupture of the end panel at the central portion 84.
[0041] Pressurised gas within the container will be permitted to harmlessly
vent through the
rupture in the central portion 84 of the moustache score 78 without affecting
the
integrity of the peripheral score 72 or accelerating the opening process. The
flow of
pressurised gas will tend to be directed harmlessly at an oblique angle
beneath the
fingers of the consumer across the top of the end panel 52 so as not to
present a hazard
to the consumer.
[0042] The presence of the flex score line 80 reduces the amount of force
that will need to
be exerted by the consumer to cause the initial rupture of the central portion
84 of the
moustache score 78.
[0043] After the convenience closure 50 has vented, the consumer will
continue to pull the
lifting ring 64 upwardly, which causes the tear or rupture in the central
portion 84 of
the moustache score 78 to enlarge. The tearing will progressively advance into
the first
and second end portions 86, 88 of the moustache score 78. At the location on
the first
and second end portions 86, 88 that is closest to the flex line score 80, the
tear line will
leave the moustache score 78 and advance directly to the respective first and
second
portions 94, 96 of the flex line score 80 along the path of the break line
scores 98, 100.
This will occur even in embodiments of the invention where the break line
scores 98,
100 are not present.
[0044] The tearing will then move laterally outwardly along the respective
first and second
portions 94, 96 of the flex line score 80. As this occurs, sufficient downward
force will
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be exerted by the nose portion 63 of the gripping tab to rupture the
peripheral score 74.
The consumer at this time may pull the lift ring 64 back to cause the
peripheral score
74 to tear, thus removing the removable portion 76 of the end panel 52 from
the fixed
portion 74.
[0045] Referring now to FIGURE 4, the tooling assembly for forming the
convenience
closure 50 according to the preferred embodiment includes a third operation
press
assembly 101 including an upper portion 102 and a lower portion 104 that are
mounted
for movement with respect to each other. The tooling assembly further
preferably
includes a first forming tool 106 for forming a top surface of the end panel
52 of the
convenience closure 50.
[0046] Looking now to FIGURE 5, it will be seen that the first forming tool
106 preferably
includes a first tool surface 108 that is constructed and arranged to form the
moustache
score 78 and a second tool surface 110 that is constructed and arranged to
form the flex
line score 80. The second tool surface 110 includes a first portion 112 for
forming the
first portion 94 of the flex line score 80 and a second portion 114 for
forming the
second portion 96 of the flex line score 80. First forming tool 106 also
preferably
includes a third tool surface 116 for forming the first break line score 98
and a fourth
tool surface 118 for forming the second break line score 100. Both the first
tool surface
108 and the second tool surface 110 are formed as projections that extend
outwardly
from the substantially flat, horizontal base surface of the first forming tool
106.
[0047] FIGURE 6 depicts a first forming tool 120 according to a modified
embodiment of
the invention. First forming tool 120 is identical in all respects to the
first forming tool
106 described above, except that it lacks the third and fourth tool surfaces
116, 118 for
forming the first and second break line scores 98, 100. First forming tool 120
would be
used to manufacture a convenience closure according to a modified embodiment
of the
invention in which the break line scores 98, 100 are not present.
[0048] A method of making such a convenience closure 50 according to the
preferred em-
bodiment of the invention would include a step of providing an end panel blank
and
providing the tooling discussed above in relation to FIGURES 4-6. The tooling
would
be used in otherwise conventional fashion to form the convenience closure that
is
discussed in detail above.
[0049] The preferred method of making the convenience closure 50 utilises a
seven
operation manufacturing process, as indicated in FIGURE 8.
[0050] The first forming operation is used to form the rivet butble
formation on the end
panel blank.
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[0051] The second forming operation completes the formation of the rivet
button and begins
the formation of a lower safety fold.
[0052] The third forming operation forms the score lines that have been
described in detail
above and pre-folds an upper safety fold.
[0053] The fourth operation completes the folding of the lower safety fold.
[0054] The fifth operation involves the staking of the tab to the end panel
and a final rivet
operation.
[0055] The sixth operation includes a tab detect function as well as a step
of forming an
upper fold pre-bulge.
[0056] The seventh and final operation involves a step of completing the
folding of the
upper fold into a position where it will afford cut protection.
[0057] Referring now to FIGURES 9 & 10, an easy open can end that is
constructed
according to a second, preferred embodiment of the invention is identical to
that
described above with regard to the first embodiment of the invention except as
otherwise described herein.
[0058] As FIGURE 10 shows, a plurality of opening scores 270 are preferably
defined in the
end panel of the can end in an area that is generally proximate to the
location of the
rivet formation 224, shown in FIGURE 9. The opening scores 270 preferably
include a
moustache score 278, a flex line score 280 and a pair of break line scores
298, 300,
which are best shown in FIGURE 10. Although in the preferred embodiment the
end
panel has all of these scores defined therein, it should be understood that in
alternative
embodiments of the invention the moustache score 278 could be provided with a
flex
line score 280, with or without a break line score.
[0059] As FIGURE 10 shows, the moustache score 278 preferably includes a
central portion
284 that is positioned radially inwardly on the end panel relative to the
rivet formation
224 and is curved about the rivet formation 224 in such a manner that a
concave side
of the central portion 284 faces the rivet formation 224. The curvature of the
central
portion 284 is preferably a constant radius of curvature.
[0060] The moustache score 278 further preferably includes first and second
end portions
286, 288 that are preferably symmetric with respect to each other about a
diametric
axis of symmetry 282 that extends through the centre of the rivet formation
224. Each
of the first and second end portions 286, 288 preferably includes a convex
side of
curvature that faces the nearest portions of the peripheral score 272. Each of
the first
and second end portions 286, 288 preferably have a constant radius of
curvature R1
that preferably extends along an arc section that is at least about 1500. The
constant
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radius of curvature R1 is preferably substantially within a range of about
0.07 inches to
about 0.2 inches.
[0061] The distal ends of the first and second end portions 286, 288 in the
preferred em-
bodiment point away from the nearest portion of the peripheral score 2E, and a
tangent line extending through the distal ends (i.e. tangential to the distal
ends) would
preferably be substantially perpendicular to a tangent line of the peripheral
score
at a location where the first tangent line would intersect the peripheral
score //2.
[0062] Preferably, a transition location 292 between the central portion
284 and the first end
portion 286 is located at a transitional angle a from the diametric axis of
symmetry
282 that is preferably substantially within a range of about 45 to about 60 .
More
preferably, this angle is substantially within a range of about 50 to about
55 .
[0063] The flex line score 280 preferably has a first portion 294 that is
located on a first side
of the rivet formation 224 and a second portion 296 that is located on a
second,
opposite side of the rivet formation 224. The first portion 294 in this
embodiment of
the invention preferably includes a substantially linear portion 304 that is
proximate to
the rivet formation 224 and a second, curved portion 306 at an end of the
first portion
294 that is distal from the rivet formation 224.
[0064] Similarly, the second portion 294 in this embodiment of the
invention preferably
includes a substantially linear portion 308 that is proximate to the rivet
formation 224
and a second, curved portion 310 at an end of the second portion 296 that is
distal from
the rivet formation 224.
[0065] One purpose of the curved portions 306, 310 is to deter possible
tearing from
occurring near the outer distal ends of the first and second flex line score
portions 294,
296 during and after opening of the easy open end by a consumer.
[0066] The first and second portions 294, 296 of the flex line score 280
are preferably
aligned and symmetric with respect to each other.
[0067] The linear portions 304, 308 of the flex line score 280 and its
components 294, 296
are preferably substantially perpendicular with respect to the diametric axis
of
symmetry 282.
[0068] The flex line score 280 preferably has a residual thickness (i.e. a
thickness that
remains in the end panel at the location of the score line 280) that is
substantially the
same as a residual thickness of the moustache score 278. The flex line score
280
further preferably has a residual thickness that is within a range of about
25% to about
40% of a thickness of the end panel. More preferably, the flex line score 280
has a
residual thickness that is substantially within a range of about 30% to about
35% of the
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thickness of the end panel.
[0069] The moustache score 278 has a residual thickness that is preferably
substantially
within a range of about 25% to about 40% of the thickness of the end panel.
More
preferably, the moustache score 278 has a residual thickness that is
substantially within
a range of about 30% to about 35% of the thickness of the end panel. The
moustache
score 278 preferably has a residual thickness that is no greater than about
0.0045
inches, and more preferably no greater than about 0.0035 inches.
[0070] As FIGURE 10 shows, the portions of the moustache score 278 that
most closely
approach the flex line score 280 present a convex side of curvature that faces
the flex
line score 280.
[0071] In this preferred embodiment of the invention, a pair of break line
scores 298, 300
are defined in the end panel in order to provide a pre-weakened tearing path
between
the moustache score 278 and the flex line score 280 that is utilised by the
convenience
closure during the preliminary stages of opening. The break line scores 298,
300 are
positioned between the moustache score 278 and the flex line score 280. Each
of the
break line scores 298, 300 are preferably substantially perpendicular to the
flex line
score 280 and are aligned with the locations on the respective first and
second end
portions 286, 288 of the moustache score 278 that most closely approach the
flex line
score 280.
[0072] The break line scores 298,300 are preferably substantially
perpendicular with respect
to tangent lines that would pass through the locations on the respective first
and second
end portions 286, 288 of the moustache score 278 that most closely approach
the flex
line score 280.
[0073] The break line scores 298, 300 preferably have a residual thickness
that is greater
than a residual thickness of the flex score line 280 and that is greater than
a residual
thickness of the moustache score 278. The residual thickness of the break line
scores
298, 300 is preferably substantially within a range of about 30% to about 95%
of the
thickness of the end panel, with a more preferred range of about 50% to about
80% of
the thickness of the end panel.
[0074] The presence of the flex score line 280 reduces the amount of force
that will need to
be exerted by the consumer to cause the initial rupture of the central portion
284 of the
moustache score 278.
[0075] Looking now to FIGURE 9, it will be seen that the first forming tool
206 preferably
includes a first tool surface 208 that is constructed and arranged to form the
moustache
score 278 and a second tool surface 210 that is constructed and arranged to
form the
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flex line score 280. The second tool surface 210 includes a first portion 212
for
forming the first linear portion 304 of the first portion 294 of the flex line
score 280
and a second portion 220 for forming the curved portion 306 of the first
portion 294 of
the flex line score 280. It further includes a third portion 214 for forming
the linear
portion 308 of the second portion 296 of the flex line score 280 and a fourth
portion
222 for forming the curved portion 310 of the second portion 296 of the flex
line score
280.
[0076] The first forming tool 206 also preferably includes a third tool
surface 216 for
forming the first break line score 298 and a fourth tool surface 218 for
forming the
second break line score 300. Both the first tool surface 208 and the second
tool surface
210 are formed as projections that extend outwardly from the substantially
flat, ho-
rizontal base surface of the first forming tool 206.
[0077] It is to be understood, however, that even though numerous
characteristics and ad-
vantages of the present invention have been set forth in the foregoing
description,
together with details of the structure and function of the invention, the
disclosure is il-
lustrative only, and changes may be made in detail, especially in matters of
shape, size
and arrangement of parts within the principles of the invention to the full
extent
indicated by the broad general meaning of the terms in which the appended
claims are
expressed.
