U.S. patent application number 09/748927 was filed with the patent office on 2002-08-22 for can end for a container.
Invention is credited to Forrest, Randy G., Turner, Timothy.
Application Number | 20020113069 09/748927 |
Document ID | / |
Family ID | 25011494 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020113069 |
Kind Code |
A1 |
Forrest, Randy G. ; et
al. |
August 22, 2002 |
Can end for a container
Abstract
An end member for a container having a circumferential sidewall,
the end member having a peripheral seaming edge adapted to be
integrally connected to the sidewall, and having a central panel
wall with a means for opening a frangible panel segment of the
panel wall is claimed. The end member comprises a deboss panel
recessed in the central panel. The deboss panel has first and
second spaced apart end portions joined by first and second
sidewalls. The first spaced apart end portion has an apex and first
and second arcuate portions. A distance between the first and
second arcuate portions is defined by a plurality of progressively
increasing secant lengths located in spaced relation from the apex.
A score groove is located within the deboss panel defining an outer
perimeter of the frangible panel segment. The score groove has a
first end and a second end joined to the first end by a curvilinear
segment. The first end and the second end are separated by a
generally linear hinge segment of the central panel wall. The
curvilinear segment includes first and second curved segments
joined by a transition point located adjacent the apex of the
deboss panel. The generally arcuate transition region is defined by
a plurality of progressively increasing chordal lengths located in
spaced relation from the apex of the deboss panel. A ratio of the
plurality of progressively increasing secant lengths to the
progressively increasing chordal lengths increases along respective
lengths of the first and second arcuate portions of the deboss
panel.
Inventors: |
Forrest, Randy G.; (Park
Ridge, IL) ; Turner, Timothy; (Pecatonica,
IL) |
Correspondence
Address: |
Peter M. Klobuchar
Wallenstein & Wagner, Ltd.
311 South Wacker Drive, 53rd Floor
Chicago
IL
60606-6630
US
|
Family ID: |
25011494 |
Appl. No.: |
09/748927 |
Filed: |
December 27, 2000 |
Current U.S.
Class: |
220/269 ;
220/906 |
Current CPC
Class: |
B65D 2517/0014 20130101;
B65D 2517/0062 20130101; B65D 17/08 20130101; B65D 2517/007
20130101; B65D 7/36 20130101; B65D 17/4012 20180101; Y10S 220/906
20130101; B65D 2517/0076 20130101 |
Class at
Publication: |
220/269 ;
220/906 |
International
Class: |
B65D 017/34 |
Claims
We claim:
1. An end member for a container, the end member having a central
panel wall with a product side and a public side, the public side
having a means for opening a frangible panel segment, the end
member comprising: a deboss panel recessed in the central panel,
the deboss panel having a profile defined by first and second
spaced apart end portions joined by first and second sidewalls; a
score groove within the deboss panel defining an outer perimeter of
the frangible panel segment, the score groove having a portion
adjacent the first spaced apart end portion of the deboss panel
wherein a distance between the deboss profile and the score groove
has an increased length.
2. The end member of claim 1 wherein the distance between the
deboss profile and the score groove is greater than 0.050
inches.
3. The end member of claim 1 wherein the distance between the
deboss profile and the score groove is between 0.050 inches and 0.1
inches.
4. The end member of claim 1 wherein the second spaced apart end
portion of the deboss panel includes first and second arcuate
portions extending outwardly from an apex, and the distance between
the score groove and the deboss profile becomes progressively
longer along at least the first or second arcuate portion.
5. The end member of claim 4 wherein the distance between the
deboss profile and the score groove becomes progressively longer
along the first and second arcuate portions.
6. The end member of claim 1 wherein the first spaced apart end
portion includes an apex and first and second arcuate portions
joining the apex with the first and second sidewalls respectively
wherein a distance between the first and second arcuate portions is
defined by a plurality of progressively increasing secant lengths
located in spaced relation from the apex, and the score groove
includes a first end and a second end joined to the first end by a
curvilinear segment, the curvilinear segment including a generally
arcuate transition region adjacent the apex of the deboss panel,
the generally arcuate transition region defined by a plurality of
progressively increasing chordal lengths located in spaced relation
from the apex of the deboss panel wherein a ratio of the plurality
of progressively increasing secant lengths to the progressively
increasing chordal lengths increases along respective lengths of
the first and second arcuate portions of the deboss panel.
7. The end member of claim 6 further comprising: a rivet located
within the deboss panel and adapted to integrally attach a tab
lever to the panel, the tab lever having a nose portion overlying
at least a portion of the frangible panel and having a lift end
opposite the nose; and a coined region having an outer periphery
located about the rivet wherein the score groove has a portion
separated from the product side of the central panel by a residual,
and the score groove includes a vent region located within the
coined region and adjacent the rivet, and a length defined by a
thickened portion of the residual located beyond the periphery of
the coined region wherein the frangible panel segment initially
opens within the vent region in response to a pulling force on the
lift end of the tab lever.
8. The end member of claim 7 further comprising a vent coin
adjacent the length of the score groove defined by a thickened
portion of the residual for placing a compressive stress on the
length of the score groove defined by a thickened portion of the
residual.
9. The end member of claim 7 further comprising an anti-fracture
score adjacent the score groove wherein the vent coin intersects
the anti-fracture score.
10. The end member of claim 1 wherein the central panel has an
outer peripheral edge segment including a stepped portion having at
least a first panel radius interconnected to a second panel
radius.
11. The end member of claim 10 further comprising a countersink
portion connected to the central panel by the outer peripheral edge
portion, the countersink including an inner wall, a curved segment,
and an outer wall, the curved segment having an inner arcuate
portion joined to an outer arcuate portion along an annular base,
the inner wall having an upper portion joined to the outer
peripheral edge portion of the center panel and a lower portion
joined to the inner portion of the curved segment, and the outer
wall having a lower portion joined to the outer portion of the
curved segment, a crease portion angled outwardly of the center
panel, and an upper portion wherein the crease is positioned at a
first height above the annular base and the second panel radius is
positioned at a second height, the second height being greater than
the first height.
12. A method of producing the end member of claim 1, the method
comprising the steps of: providing an end member including a
central panel wall with a product side and a public side, a
countersink, and an outer peripheral edge; forming the score groove
within the central panel; coining the outer peripheral edge of the
metal blank; reforming the countersink downwardly with respect to
the central panel; forming the deboss panel within the central
panel and spaced from the outer peripheral edge; and reforming the
outer peripheral edge of the end member wherein the outer
peripheral edge portion includes a first panel radius
interconnected to a second panel radius.
13. An end member for a container having a circumferential
sidewall, the end member having a peripheral seaming edge adapted
to be integrally connected to the sidewall, and having a central
panel wall with a product side and a public side, the public side
having a means for opening a frangible panel segment, the end
member comprising: a rivet positioned within the central panel and
adapted to integrally attach a tab lever to the panel, the tab
lever having a nose portion overlying at least a portion of the
frangible panel segment and having a lift end opposite the nose; a
coined region substantially surrounding the rivet, the coined
region coin having an outer periphery; a score groove in the
central panel defining an outer perimeter of the frangible panel
segment, the score groove having a portion separated from the
product side of the central panel by a residual; a vent region
located adjacent the rivet, a portion of the vent region located
within the coined region, the frangible panel segment opening
initially within the vent region in response to a pulling force on
the lift end of the tab lever; and a length of the score groove
defined by a thickened portion of the residual located beyond the
periphery of the coined region.
14. The end member of claim 13 further comprising a vent coin
adjacent the length of the score groove defined by a thickened
portion of the residual for placing a compressive stress on the
length of the score groove defined by a thickened portion of the
residual.
15. The end member of claim 14 further comprising an anti-fracture
score adjacent the score groove wherein the vent coin intersects
the anti-fracture score.
16. The end member of claim 15 wherein the vent coin is located
beyond the periphery of the coined region substantially surrounding
the rivet.
17. The end member of claim 16 wherein the length of the score
groove defined by a thickened portion of the residual is located
entirely beyond the periphery of the coined region substantially
surrounding the rivet.
18. The end member of claim 13 wherein the central panel has an
outer peripheral edge segment including a stepped portion having at
least a first panel radius interconnected to a second panel
radius.
19. The end member of claim 18 further comprising a countersink
portion connected to the central panel by the outer peripheral edge
portion, the countersink including an inner wall, a curved segment,
and an outer wall, the curved segment including an inner arcuate
portion joined to an outer arcuate portion along an annular base,
the inner wall including an upper portion joined to the outer
peripheral edge portion of the center panel and a lower portion
joined to the inner portion of the curved segment, and the outer
wall including a lower portion joined to the outer portion of the
curved segment, a crease portion angled outwardly of the center
panel, and an upper portion wherein the crease is positioned at a
first height above the annular base and the second panel radius is
positioned at a second height, the second height being greater than
the first height.
20. The end member of claim 19 further comprising a deboss panel
recessed in the central panel, the deboss panel including a profile
defined by first and second spaced apart end portions joined by
first and second sidewalls, the first spaced apart end portion
including an apex and first and second arcuate portions joining the
apex with the first and second sidewalls respectively wherein a
distance between the first and second arcuate portions is defined
by a plurality of progressively increasing secant lengths located
in spaced relation from the apex, and the curvilinear segment of
the score groove including a generally arcuate transition region
adjacent the generally arcuate apex portion of the deboss panel,
the generally arcuate transition region defined by a plurality of
progressively increasing chordal lengths located in spaced relation
from the apex of the deboss panel wherein a ratio of the plurality
of progressively increasing secant lengths to the progressively
increasing chordal lengths increases along respective lengths of
the first and second arcuate portions of the deboss panel.
21. The end member of claim 13 the thickened portion of the
residual includes a first region and a second region, the residual
located within the first region having a greater thickness than the
residual located within the second region.
22. The end member of claim 21 wherein the first region is located
adjacent the coined region substantially surrounding the rivet.
23. An end closure for a container, comprising: a central panel
having a public side and an opposing product side and an outer
peripheral edge segment, the outer peripheral edge segment
including a stepped portion including a first panel radius
interconnected to a second panel radius; a countersink connected to
the central panel by the outer peripheral edge portion, the
countersink including an inner wall, a curved segment, and an outer
wall, the curved segment including an inner arcuate portion joined
to an outer arcuate portion along an annular base, the inner wall
including an upper portion joined to the outer peripheral edge
portion of the center panel and a lower portion joined to the inner
portion of the curved segment, and the outer wall including a lower
portion joined to the outer portion of the curved segment, a crease
portion angled outwardly of the center panel, and an upper portion
wherein the crease is positioned at a first height above the
annular base and the second panel radius is positioned at a second
height, the second height being greater than the first height; and
a seaming curl joined to the upper portion of the outer wall for
joining the end closure to a container.
24. The end closure of claim 23 further comprising: a rivet
centrally recessed within the central panel and adapted to
integrally attach a tab lever to the panel; a coined region
substantially surrounding the rivet, the coined region having an
outer periphery; a score groove in the central panel defining an
outer perimeter of the frangible panel segment, the score groove
having a first end and a second end joined to the first end by a
curvilinear segment, the score groove including a portion separated
from product side of the central panel by a residual; a vent
region, a portion of the vent region located within the coined
region adjacent the rivet, the frangible panel segment opening
initially within the vent region in response to a pulling force on
the lift end of the tab lever; and a length of the score groove
defined by a thickened portion of the residual located within the
vent region and beyond the periphery of the coined region.
25. The end closure of claim 24 further comprising a vent coin
adjacent the length of the score groove defined by a thickened
portion of the residual for placing a compressive stress on the
length of the score groove defined by a thickened portion of the
residual.
26. The end closure of claim 25 further comprising an anti-fracture
score adjacent the score groove wherein the vent coin intersects
the anti-fracture score.
27. The end closure of claim 24 wherein the vent coin is located
beyond the periphery of the coined region substantially surrounding
the rivet.
28. The end closure of claim 23 further comprising a deboss panel
recessed in the central panel, the deboss panel including a profile
defined by first and second spaced apart end portions joined by
first and second sidewalls, the first spaced apart end portion
including an apex and first and second arcuate portions joining the
apex with the first and second sidewalls respectively wherein a
distance between the first and second arcuate portions is defined
by a plurality of progressively increasing secant lengths located
in spaced relation from the apex, and the curvilinear segment of
the score groove including a generally arcuate transition region
adjacent the generally arcuate apex portion of the deboss panel,
the generally arcuate transition region defined by a plurality of
progressively increasing chordal lengths located in spaced relation
from the apex of the deboss panel wherein a ratio of the plurality
of progressively increasing secant lengths to the progressively
increasing chordal lengths increases along respective lengths of
the first and second arcuate portions of the deboss panel.
29. An end member for a container, the end member comprising: a
central panel wall having a product side and a public side, the
public side a frangible panel segment and a means for opening the
frangible panel segment; a deboss panel recessed in the central
panel, the deboss panel having a substantially gibbous-shaped
profile defined by first and second spaced apart end portions
joined by first and second substantially linear sidewalls; a score
groove within the deboss panel defining an outer perimeter of the
frangible panel segment, the score groove having a portion adjacent
the first spaced apart end portion of the deboss panel wherein a
distance between the deboss profile and the score groove has an
increased length.
30. The end member of claim 29 wherein the distance between the
deboss profile and the score groove is greater than 0.050
inches.
31. The end member of claim 29 wherein the distance between the
deboss profile and the score groove is between 0.050 inches and 0.1
inches.
32. The end member of claim 29 wherein the second spaced apart end
portion of the deboss panel includes first and second arcuate
portions extending outwardly from an apex, and the distance between
the score groove and the deboss profile becomes progressively
longer along at least the first or second arcuate portion.
33. An end member for a container, the end member comprising: a
central panel wall having a product side and a public side, the
public side a frangible panel segment and a means for opening the
frangible panel segment; a deboss panel recessed in the central
panel, the deboss panel having a substantially pear-shaped profile
defined by first and second spaced apart end portions joined by
first and second curvilinear sidewalls; a score groove within the
deboss panel defining an outer perimeter of the frangible panel
segment, the score groove having a portion adjacent the first
spaced apart end portion of the deboss panel wherein a distance
between the deboss profile and the score groove has an increased
length.
34. The end member of claim 33 wherein the second spaced apart end
portion of the deboss panel includes first and second arcuate
portions extending outwardly from an apex, and the distance between
the score groove and the deboss profile becomes progressively
longer along at least the first or second arcuate portion.
35. The end member of claim 33 wherein the distance between the
deboss profile and the score groove is greater than 0.050
inches.
36. The end member of claim 35 wherein the distance between the
deboss profile and the score groove remains substantially constant
throughout the second end portion of the deboss profile.
37. The end member of claim 33 wherein the distance between the
deboss profile and the score groove is between 0.050 inches and 0.1
inches.
38. The end member of claim 37 wherein the distance between the
deboss profile and the score groove remains substantially constant
throughout the second end portion of the deboss profile.
Description
TECHNICAL FIELD
[0001] The present invention relates to end closures for two-piece
beer and beverage metal containers having a non-detachable
operating panel. More specifically, the present invention relates
to improved forming techniques to produce a lightweight end
closure.
BACKGROUND OF THE INVENTION
[0002] Common end closures for beer and beverage containers have a
central panel that has a frangible panel (sometimes called a "tear
panel," "opening panel," or "pour panel") defined by a score formed
on the outer surface, the "consumer side," of the end closure.
Popular "ecology" can ends are designed to provide a way of opening
the end by fracturing the scored metal of the panel, while not
allowing separation of any parts of the end. For example, the most
common such beverage container end has a tear panel that is
retained to the end by a non-scored hinge region joining the tear
panel to the reminder of the end, with a rivet to attach a leverage
tab provided for opening the tear panel. This type of container
end, typically called a "stay-on-tab" ("SOT") end has a tear panel
that is defined by an incomplete circular-shaped score, with the
non-scored segment serving as the retaining fragment of metal at
the hinge-line of the displacement of the tear panel.
[0003] The container is typically a drawn and ironed metal can,
usually constructed from a thin plate of aluminum. End closures for
such containers are also typically constructed from a cut-edge of
thin plate of aluminum or steel, formed into a blank end, and
manufactured into a finished end by a process often referred to as
end conversion. These ends are formed in the process of first
forming a cut-edge of thin metal, forming a blank end from the
cut-edge, and converting the blank into an end closure which may be
seamed onto a container. Although not presently a popular
alternative, such containers and/or ends may be constructed of
plastic material, with similar construction of non-detachable parts
provided for openability.
[0004] These types of "stay-on-tab" ecology container ends have
been used for many years, with a retained tab and a tear panel of
various different shapes and sizes. Throughout the use of such
ends, manufacturers have sought to save the expense of the metal by
down-gauging the metal of the ends and the tabs. However, because
ends are used for containers with pressurized contents and are
sometimes subject to pasteurization, there are conditions causing
great stresses to the components of the end during pasteurization,
transit and during opening by a user. These conditions limit the
available gauge reduction of the end metal, and make it difficult
to alter design characteristics of the end, such as by reducing
metal gauge or the thickness of the metal residual in the score
defining the tear panel.
[0005] The pressurized contents of the container often causes the
end to buckle. The pressurized contents will also force the tabs
upwardly. There is a maximum allowable distance that the tab can be
displaced without the tab extending upwardly above the remainder of
the container. This is called tab-over-chime. Tab-over-chime leads
to ship abuse problems wherein the frangible panel prematurely
fractures during distribution of filled beverage containers.
[0006] As manufacturers reduce the thickness of the metal used to
make the ends, buckle and tab-over-chime become more and more of a
problem. Therefore, a need for can end with improved ability to
withstand buckle and tab-over-chime is needed.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to provide an end
closure for a container having a circumferential sidewall and a
peripheral seaming edge adapted to be integrally connected to the
sidewall. The end has a central panel wall with a deboss portion
recessed therein. The deboss panel includes a means for opening a
frangible panel segment of the panel wall and a rivet adapted to
integrally attach a tab lever having a nose portion overlying at
least a vent region of the frangible panel segment and a lift end
opposite the nose. A score groove is formed in the central panel
wall to define an outer perimeter of the frangible panel. The score
groove has a first end adjacent the vent region and a second end
joined to the first end by a curvilinear segment, whereby the first
end and the second end are separated by a generally linear hinge
segment of the central panel wall. The hinge segment is
non-frangible to integrally connect the frangible panel segment to
an adjacent area of the panel.
[0008] It is also an object of the present invention to provide
such an end member wherein the central panel has a stepped profile
along an outer peripheral portion.
[0009] It is another object of the present invention to provide an
end member whereby the score groove is a generally v-shaped recess
having a score depth into the thickness of the central panel, and
the second groove is also a generally v-shaped recess having a
groove depth into the thickness of the central panel less than that
of the score groove. The score groove includes a check slot region
for naturally slowing the fracture of the score to allow the
container to vent safely.
[0010] It is further an object of the invention to provide an end
member having a countersink with an inner wall, a curved segment,
and an outer wall. The outer wall has a lower portion joined to an
outer arcuate portion of the curved segment, a crease portion
angled outwardly of the central panel, and an upper portion.
[0011] Other features and advantages of the invention will be
apparent from the following specification taken in conjunction with
the following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a top view of a can end of the present invention
without a tab;
[0013] FIG. 1A is a top view of the can end of FIG. 1 with a tab
staked thereto;
[0014] FIG. 2 is a partial top view of the can end of FIG. 1;
[0015] FIG. 3A is a partial cross-sectional view of taken along
3A-3A of FIG. 2;
[0016] FIG. 3B is a partial cross-sectional view of taken along
3B-3B of FIG. 2;
[0017] FIG. 4 is a cross-sectional view of the can end of FIG. 1
taken along 4-4;
[0018] FIG. 5 is a partial view of a deboss panel of the present
invention; and
[0019] FIG. 6 is a top view of a can end of the present invention
without a tab.
DETAILED DESCRIPTION
[0020] While this invention is susceptible of embodiment in many
different forms, there are shown in the drawings and will herein be
described in detail preferred embodiments of the invention with the
understanding that the present disclosure is to be considered as an
exemplification of the principles of the invention and is not
intended to limit the broad aspect of the invention to the
embodiments illustrated.
[0021] The container end of the present invention is a stay-on-tab
10 end member 10 with improved physical properties including
strength. Essentially, the present invention provides a lightweight
end member 10 which embodies the physical characteristics and
properties required in the beverage container market, as explained
below.
[0022] In the embodiment of FIGS. 1 through 6, the end member 10
for a container (not shown) has a central panel wall 12 having a
seaming curl 14 for joining the wall to the container. The
container is typically a drawn and ironed metal can, usually
constructed from a thin plate of aluminum or steel, such as the
common beer and beverage containers. End closures for such
containers are also typically constructed from a cut edge of thin
plate of aluminum or steel, formed into blank end, and manufactured
into a finished end by a process often referred to as end
conversion. In the embodiment shown in the Figures, the central
panel 12 is joined to a container by a seaming curl 14 which is
joined to a mating curl of the container. The seaming curl 14 of
the end closure 10 is integral with the central panel 12 by a
countersink area 16 which is joined to the panel outer peripheral
edge 18 of the central panel 12. This type of means for joining the
central panel 12 to a container is presently the typical means for
joining used in the industry, and the structure described above is
formed in the process of forming the blank end from a cut edge of
metal plate, prior to the end conversion process. However, other
means for joining the central panel 12 to a container may be
employed with the present invention.
[0023] The outer peripheral edge 18 of the central panel 12 is
typically coined to add strength to can end 10. Coining is the work
hardening of metal between tools. The metal is typically compressed
between a pair of tools, generally an upper and lower tool.
[0024] The central panel wall 12 has a displaceable tear panel 20
defined by a curvilinear frangible score 22 with an adjacent
anti-fracture score 24 on the tear panel 20, and a non-frangible
hinge segment 26. The hinge segment 26 is defined by a generally
straight line between a first end 28 and a second end 30 of the
frangible score 22. The tear panel 20 of the central panel 12 may
be opened, that is the frangible score 22 may be severed and the
tear panel 20 displaced at an angular orientation relative to the
remaining portion of the central panel 12, while the tear panel 20
remains hingedly connected to the central panel 12 through the
hinge segment 26. In this opening operation, the tear panel 20 is
displaced at an angular deflection, as it is opened by being
displaced away from the plane of the panel 12.
[0025] The first and second ends 28, 30 of the frangible score 22
are joined by a curvilinear segment 32. The curvilinear segment 32
includes first and second curved segments 33a, 33b joined by an
arcuate transition region 34 which lies adjacent the outer
peripheral edge 18 of the center panel 12 and are defined by a
radius of curvature R.sub.4. (See FIG. 5). The first and second
curved segments 33a, 33b are separated by a series of chordal
lengths 31a-33d. (See FIG. 5).
[0026] As best shown in FIG. 3B, the frangible score 22 is
preferably a generally V-shaped groove 35 formed into the public
side 34a of the panel wall 12. Similarly, the anti-fracture score
24, is preferably a generally V-shaped groove 38 formed into the
public side 34a of the panel wall 12 on the tear panel 20. As is
explained in more detail below, the frangible score groove 35 is
preferably deeper than the anti-fracture score groove 38.
Accordingly, the score residual 40, being the amount of frangible
material remaining below the frangible score groove 35, is less
than the adjacent anti-fracture score residual 42. This difference
between score residual 40 and adjacent anti-fracture score residual
42 is the score residual differential.
[0027] The frangible score 22 and the second groove or
anti-fracture score 24 are formed using conventional-type of
scoring operation during the can end forming process, using tools
including an upper (public side) die with a score knife and a lower
(product side) die with an anvil surface.
[0028] The score residual differential is adapted to provide a tear
panel 20 with a score 22 more readily frangible than the
anti-fracture score 24, a significant factor for providing
efficient opening of the end member 10. Having a double score of a
frangible score 22 and an anti-fracture score 24 wherein there is a
score residual differential is common in the industry.
[0029] As illustrated in FIG. 1A, end member 10 has a tab 44
secured to the end panel 12 by a rivet 46. The tab 44 has a lift
end 48, a central region 50, and a nose portion 52. The lift end 48
and the nose portion 52 are generally aligned along a central
longitudinal axis passing through the rivet 46. A bead 56 is
optionally formed in the tear panel 20 inward of the score 22 and
the anti-fracture score 24. The tear panel bead 56 is useful to
draw excess metal, or slack of metal, from the tear panel 20 to
tighten the metal of the tear panel 20 and improve opening
characteristics of the end member 10 by the tab 44 being lifted to
push against the tear panel 20.
[0030] The rivet 46 is formed in the typical manner. It is the
conventional practice to coin the metal on the central panel 12
proximate the base of the rivet 46 during formation thereof. When
the rivet 46 is completely formed in the central panel 12, a coined
region 58 having a generally circular periphery is also formed and
is located about the rivet 46. This coined region 58 is typically
called a button coin.
[0031] The user initiates opening of the end member 10 by lifting
the lift end 48 of the tab 44. This lifts the rivet 46 which causes
the score groove 22 to fracture in a vent region 60 which is
located at least partially within the bounds of the coined region
surrounding the rivet 46. As the nose portion 52 presses against
the tear panel 20, the fracture of the score 22 propagates around
the tear panel 20, preferably in progression from the first end 28
of the score 22 toward the second end 30 of the score 22.
[0032] The frangible score 22 includes a length defined by a
thickened portion of the residual. This length is often referred to
as a check slot region 62. As illustrated in FIG. 3A, the check
slot 62 includes an area of thickened residual 64. The area
thickened residual 64 causes the propagation of the fracture of the
frangible score 22 to slow naturally as the fracture reaches the
check slot region 62. This allows the container to vent safely
before the fracture of the frangible score 22 continues.
[0033] Typically, the check slot 62 is located within the bounds of
the coined region 58. The check slot 62 of the present invention,
however, is located beyond the boundary of the coined region 58.
Thus, the check slot 62 is not located within the thinned metal of
the coined region 58 surrounding the rivet 46. This is advantageous
for reasons which will be discussed below.
[0034] Preferably, the check slot region 62 includes a duel step
residual differential. (See FIG. 3A). The dual step residual
differential includes two levels of residual thickness. Thus, the
check slot region 62, rather than having a constant residual
thickness, includes a first step 63a wherein the residual
differential between the first step 63a and substantially the
remaining portions of the frangible score 22 is approximately
0.0020 inches and a second step 63b wherein the residual
differential between the second step 63b and substantially the
remaining portions of the frangible score 22 is approximately
0.0016 inches thick.
[0035] The end member 10 also includes a vent coin 65. The vent
coin 65 is a small rectangularly shaped coin placed near the
frangible score 22. The vent coin 65 has a leading end 66 placed
adjacent the frangible score 22 and a trailing end 67 directed
outwardly and at an angle from the frangible score 22. An
intermediate section 68 of the vent coin 65 intersects the
anti-fracture score 24.
[0036] One purpose of the vent coin 65 is to prevent the tear panel
20 from missiling during the opening of the container. Missiling is
a jutting upward of the tear panel 20 upon venting. Missiling is
caused when the frangible score 22 fracture propagates beyond the
vent region 60, before the container pressure is fully relieved.
The loose tear panel 20 is then forced upward due to the internal
pressure of the container.
[0037] The end member 10 is opened by the lifting of the rivet and
subsequently by the force of the tab 44 pushing down on the tear
panel 20. Initially, the frangible score 22 should only be severed
in the vent region 60. This allows a small portion of the tear
panel 20 metal to be pushed below the central panel 12 to open and
vent the pressure within the container.
[0038] The vent coin 65 functions by displacing metal near the
juncture of the check slot 62 and the vent region 60. The displaced
metal in the area causes an elastic, compressive state. As such,
when the frangible score 22 is severed in the vent region 60, the
metal of the tear panel 20 springs out to underlap the metal of the
central panel 12 in that region. This underlapping portion of the
tear panel 20 is believed to keep the remainder of the tear panel
20 in place so as to avoid premature fracture of the remainder of
the frangible score 22 and thereby prevent the tear panel 20 from
missiling.
[0039] Typically, the vent coin 65 is located within the coined
region 58. Similar to the check shot 62 of the present invention,
the vent coin 65 is moved outside of the periphery of the coined
region 58 surrounding the rivet 46. It is believed that by moving
the vent coin 62 outside of the coined region 58 boundary, the
compressive stress on the frangible score 22 is increased.
Therefore, the depth of frangible score 22 in the vent region 60
may be increased, and the strength requirement of the tab 44 to
begin fracture of the frangible score 22 can be decreased.
[0040] The vent coin 65 also interacts with the check slot 62 to
slow the propagation of the fracture along the frangible score 22
during venting of the container.
[0041] According to another aspect of the present invention, a
deboss panel 69 is formed in the public side 34a of the central
panel 12. The deboss panel 69 is formed in the central panel 12
using conventional die-forming techniques. As shown in FIGS. 1 and
1A, the deboss panel 69 has a substantially gibbous-shaped deboss
profile 70 which is, in turn, defined by an inner radius line 72
and an outer radius line 74. As illustrated in FIG. 4, the outer
radius line 74 may have a radius of curvature of about 0.015 inches
with a center of curvature below a product side 34b of the central
panel 12 and the inner radius line 72 may have a radius of
curvature of 0.015 inches with a center of curvature above public
side 34a of the central panel 12. The depth of the deboss profile
70, i.e., the vertical distance between outer radius line 74 and
inner radius line 72 may be about 0.019 inches. The width of the
deboss profile, i.e., the lateral distance between the outer and
inner radius lines 74, 72, may be about 0.015 inches. The deboss
panel 69 has bilateral symmetry with respect to a plane defined by
axes X-X and Y-Y.
[0042] The deboss profile 70 includes first and second opposing end
portions 76, 78 joined by a pair of sidewalls 80a, 80b. The first
end portion 76 includes an apex 82. The apex 82 is joined to the
sidewalls 80a, 80b by first and second arcuate portions 84a, 84b.
The apex 82 lies between the transition region 34 of the frangible
score 22 and the outer peripheral edge 18 of the center panel 12.
The first and second arcuate portions 84a, 84b extend outwardly
equally from the apex 82 along a first angle 86 such that a series
of secant lengths 88a-88d arranged parallel to the Y-Y axis and
opposite the apex 82 become progressively longer in length until
the first and second arcuate portions 84a, 84b blend smoothly with
the sidewalls 80a, 80b. (See FIG. 5). The apex 82 may also be
described as having a radius of curvature R.sub.5 wherein the
arcuate portions 84a, 84b become increasingly farther and farther
apart until each blends with a respective sidewall 80a, 80b.
[0043] It should be noted that in the embodiment illustrated in
FIG. 5, the sidewalls 80a, 80b are substantially straight segments.
The sidewalls 80a, 80b, however, may curvilinear or any shape
without departing from the spirit of the invention. For instance,
FIG. 6 illustrates sidewalls 80a, 80b having a curvilinear
shape.
[0044] Typically, the deboss profile 70 and the frangible score 22
remain equidistant throughout the first end portion 76. The
distance between the frangible score 22 and the first end portion
68 of the deboss profile 70 is generally on the order of 0.05
inches.
[0045] As illustrated in FIG. 5, the present invention discloses a
widening of the distance between the first end portion 76 of the
deboss profile 70 and the curved segments 33a, 33b of the frangible
score 22. At the apex 82 of the first end portion 76, the distance
D.sub.0 between the deboss profile 70 and the frangible score 22 is
about 0.05 inches. The distances D.sub.1-D.sub.3 increase gradually
as the ratio of the secant lengths 88a-88d of the deboss profile 70
to the chordal lengths 31a-33d of the frangible score 22 increases.
At the points where the first and second arcuate portions 84a, 84b
blend into the sidewalls 82a, 82b, the distance D.sub.4 between the
deboss profile 70 and the frangible score 22 is about 0.1
inches.
[0046] Alternatively, as illustrated in FIG. 6, the distance
between the deboss profile 70 and the frangible score 22 can be
increased while remaining substantially constant. In this
embodiment, the distance between the deboss profile 70 and the
frangible score 22 is increased from 0.050 inches to approximately
0.1 inches. The distance is preferably maintained at 0.1 inches but
also may be within the range of 0.05-0.1 inches, or any range or
combination of ranges therein.
[0047] The relationship between the deboss panel 69 and the
frangible score 22 is important. The deboss panel 69 takes up metal
displaced during the scoring process and the coining of the
peripheral edge 18. Also, by moving the deboss panel 69 outwardly
from the frangible score 22, it is believed that the stresses
created on the frangible score 22 during the forming of the deboss
panel 69 are greatly reduced. This is believed to enhance score
rupturing by taking up metal slack near the rivet 46 and also
immediately adjacent to the frangible score 22 along its entire
length from the 6 o'clock past the 9 o'clock position, the region
where score rupture failure is most likely to occur. Thus, the
widening of the deboss panel 69 also increases burst values by
relieving the stresses on the frangible score 22. The end member 10
is also strengthened because the movement of the deboss panel 69
outwardly allows the panel to be recessed deeper, taking up even
more loose metal.
[0048] Generally, the central panel 12 experiences stress
gradients. As the distance from the rivet 46 (center of the central
panel 12) becomes greater, the stress lessens. Thus, by moving the
deboss panel 69 away from the frangible score 22, the component of
stress supplied by the deboss panel 69 is reduced. Thus, the depth
of frangible score 22 may be increased as much as 50% without
incurring premature failure of the frangible score 22.
[0049] According to another aspect of the present invention and as
illustrated in FIGS. 5 and 6, a curvilinear bead 89 is formed in
the public side 34a of the central panel 12. The bead 89 is
preferably formed to have a curvilinear length, adapted to at least
partially surround the coined region 58, thereby partially
surrounding the rivet 46. Further, the bead 89 is preferably an
emboss bead or a raised portion in the public side 34a of the
central wall 12.
[0050] The bead 89 provides the desirable stiffness of the central
panel 12 in the region around the rivet 46, thereby reducing the
amount of panel lift resulting from the force of the tab 44 on the
tear panel 20 during opening. The stiffness of the tear panel 20 is
primarily provided by the bead 89 being formed as drawn metal in
the public side 34a of the central panel 12 immediately adjacent
the coined region 58 and the rivet 46.
[0051] The bead 89 preferably has an arcuate portion and a
substantially linear portion. The arcuate portion partially
surrounds the coined region 58, extending a slightly longer
distance on one side of the coined region 58 than on an opposing
side of the coined region 58. This allows the first end 28 of the
score 22 to extend upwardly so that it wraps slights around the
rivet 46. The substantially linear portion is located on an
opposite side of the coined region 58 as the frangible score
22.
[0052] Preferably, there is very little thinning of the metal
during formation of the bead 89, and the bead 89 is instead created
by forming or drawing the metal between two opposed dies to take up
slack metal. The bead 89 formation thereby draws available loose
metal in the region, such as loose metal caused by scoring, coining
of the metal while forming the rivet 46, or coining of metal while
staking the tab 44. The bead 89 also serves as a stiffening beam in
the panel 12 wall immediately adjacent the rivet 46 and the coined
region 58. By drawing loose metal and providing a stiffening beam,
the bead 89 is adapted to provide stiffness in the panel wall 12
around the coined region 58 to decrease the panel lift and enhance
the leverage by the tab 44 during opening of the end tear panel
20.
[0053] Referring to FIG. 4, the countersink 16 of the end member 10
includes an inner wall 90, a curved segment 92, and an outer wall
94. The curved segment 92 has an inner arcuate portion 96 joined to
an outer arcuate portion 98 along an annular base 100. The inner
wall 90 has an upper portion 102 joined to the outer peripheral
edge portion 18 of the central panel 12 and a lower portion 104
joined to the inner arcuate portion 96 of the curved segment 92.
The outer wall 94 has a lower portion 106 joined to the outer
arcuate portion 98 of the curved segment 92, a crease portion 108
angled outwardly of the central panel 12, and an upper portion 110.
The crease 108 has a radius of curvature of approximately 0.005
inches and is positioned at a height H.sub.1 of approximately 0.065
inches above the annular base 100.
[0054] The outer peripheral edge 18 of the central panel 12
includes a stepped profile. The stepped profile includes a first
panel radius 114 interconnected to a second panel radius 116 by the
previously coined portion of the outer peripheral edge 18. The
first panel radius 114 has a height H.sub.2 which is approximately
0.108 inches above the annular base 100. The second panel radius
116 is joined to the inner wall 90 of the countersink 16 and has a
height H.sub.3 which is approximately 0.093 inches above the
annular base 100.
[0055] The dimensions of the first panel radius 114, the second
panel radius 116, and the crease portion 108 were selected to
optimize resistance to burst and tab-over-chime. Burst is the
ability of the pour panel 20 to withstand internal pressure.
Tab-over-chime is also the ability of the end member 10 to
withstand internal pressure. Tab-over-chime occurs when the
internal pressure forces the tab 44 upwardly. When the tab 44 is
displaced upward, it can lead to ship abuse during distribution of
filled containers which can cause premature failure of the pour
panel 20. Thus, tab-over-chime is the internal pressure at which
the tab is displaced an undesirable amount.
[0056] As the height H.sub.3 of the second panel radius 116
increases, buckle values increase; however, the tab-over-chime
value decreases as the height H.sub.3 of the second panel radius
116 increases. Thus, the height H.sub.1 of the crease portion 108
can be 0.060-0.075 inches or any height or range of heights
therein, and the height H.sub.3 of the second panel radius 116 can
be 0.080-0.095 inches or any height or range of heights therein. It
should be noted that for forming reasons, the height H.sub.1 of the
crease 108 is preferably lower than the height H.sub.3 of the
second panel radius 116.
[0057] According to another aspect of the invention, a method for
reforming a can end shell to produce the end member 10 described
herein is disclosed. The method is used to produce a lightweight
end member 10, for example from an 0.0080 inch thick aluminum stock
for attachment to a container necked to a 202 (2.125 inches) open
end. End members 10 of the present invention are generally
manufactured using a multi-stage reforming method.
[0058] In an the initial stage, the outer peripheral edge 18 of the
central panel 12 is coined and reformed in the conventional manner
as disclosed, for example, in U.S. Pat. No. 5,527,442. The coining
operation creates slack metal produced by the compression of the
peripheral edge 18 between the coining tools. This coining
operation forces metal in the outer peripheral edge to flow both
radially inwardly and radially outwardly from the peripheral edge
18.
[0059] The slack metal is removed as the countersink 16 is
reformed. In this operation, the countersink 16 is reformed so that
metal in the countersink 16 is moved downwardly with respect to the
central panel 12. This decreases the countersink 16 depth which
causes the central panel 12 height to increase. To further improve
end member 10 rock and buckle performance, the outer wall of the
countersink 16 may also be creased or kinked radially outwardly, as
illustrated in FIG. 4, during the reforming operation. This type of
operation is disclosed in U.S. Pat. No. 4,093,102.
[0060] Next, the deboss panel 69 is formed within the central panel
12. The forming of the deboss panel 69 places the central panel 12
into the desirable tension state. The deboss panel 69 also takes up
any slack metal created during the coining of the peripheral edge
18 and the scoring of the central panel 12 when the frangible score
22 and the anti-fracture score 24 are formed.
[0061] Once the tab 44 has been staked to the rivet 46, the step
portion is formed at the outer peripheral portion 18. The step
portion increases the height of the central panel 12 above that of
the initial reform increase. The forming of the step portion
increases the end member's 10 buckle resistance even higher. Also,
since no slack metal is remaining from the coining and scoring
operations, it has been found that the deboss panel 69 will roll up
or the recess will become shallower subsequent to the step portion
being formed.
[0062] In an initial trial, can ends 10 were produced with a check
slot region 62 having a single step of residual thickness of 0.0016
ins., a vent coin 65 positioned below the anti-fracture score 24,
and a 6:00-12:00 score residual differential of only 0.0002-0.0004
ins. This trial resulted in improved openability.
[0063] A second trial was carried out on can ends 10 as illustrated
in FIGS. 5. The lengths of increased residual 62 of these can ends
10 were modified to create the dual step residual differential to
the frangible score 22 of 0.0020 ins. and 0.0016 ins. All of the
can ends 10 exhibited improved openablility and passed the
missiling test. It is believed that these favorable results are
attributable to the tear panel 20 hinging at, or opening to, the
vent coin 65 when the can end 10 end is "popped" or when opening is
initialized. This creates a larger vent opening and allows the can
end 10 to vent and pass the missiling test.
[0064] Since the can ends 10 successfully passed the missiling
test, a complete evaluation was performed. Further tests on a total
of eight sets of can ends 10, as illustrated in FIGS. 1-4 were
performed. All of the forming variables of the eight sets of can
ends 10 were identical except for the score residuals of the
frangible score 22. The different score residuals are summarized in
Table 1.
1TABLE 1 Score Residuals (in inches) Residual at Residual at
Residual at Residual at the 12:00 the 3:00 the 9:00 the 6:00 Test
Group Position Position Position Position A 0.0030 0.0029 0.0029
0.0028 B 0.0033 0.0033 0.0033 0.0032 C 0.0034 0.0034 0.0034 0.0032
D 0.0036 0.0035 0.0035 0.0034 E 0.0038 0.0037 0.0037 0.0035 F
0.0042 0.0042 0.0042 0.0040 G 0.0045 0.0044 0.0044 0.0041 H 0.0047
0.0046 0.0046 0.0043
[0065] The can ends 10 were also tested for pressurized openability
(for beer). No failures were found until test group H.
[0066] The can ends 10 were further tested for score burst. None of
the can ends 10 burst open before the maximum pressure of the test
was reached. It is believed that the excellent results of this test
are directly attributable to the greater distance from the deboss
panel 69 to the frangible score 22.
[0067] While the invention has been described with reference to
preferred embodiments, it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the broader
aspects of the invention. Also, it is intended that broad claims
not specifying details of the particular embodiments disclosed
herein as the best mode contemplated for carrying out the invention
should not be limited to such details.
* * * * *