LANGUETTE RIVEE SUR COUVERCIE FACILE A OUVRIR

RIVET PANEL (BELLOW) FOR EASY-O END RIVET STRUCTURE

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
An improved pull tab mounting arrangement provides
an movable fulcrum to facilitate opening a self-opening can.
An expandable pleat is formed in the end panel at the base
of the tab-attaching rivet and the tab is mounted with its
nose portion in spaced relation above and radially inward
of the opening score line. As the finger ring portion of
the tab is lifted, the pleat unfolds, allowing both the
rivet and the tab to travel upwardly and outwardly to
bring the tab nose into contact with the score line. This
displacement moves the fulcrum point of the tab toward the
nose portion and away from the finger ring portion, thereby
providing increased leverage and reducing the effort required
to fracture the score line. In addition, the stress placed
on the tab and the end panel during opening is reduced,
thereby permitting the use of thinner gauge metal for these
members. Further, spacing of the nose portion and the
score line reduces the probability that mishandling of the
container will result in an unintentional fracture of the
score.

Revendications

The embodiments of the invention in which an ex-
clusive property or privilege is claimed are defined as follows:
1. An improved pull tab mounting arrangement for a
self-opening end closure for a can or similar container, said
end closure comprising an end panel, attachment means formed
in said end panel, a pull tab attached by said attachment
means to said end panel, and a score line formed in said end
panel and defining an opening flap therein, the improvement
comprising unfoldable means comprising a pleat closely
surrounding said attachment means for shiftably mounting
said attachment means in said end panel for relieving stresses
on said pull tab and said end panel during lifting movements
of said tab for opening of said container.
2. The improved pull tab mounting arrangement as
described in claim 1, wherein said unfoldable mounting means
unfolds upon commencement of said opening of said container,
thereby displacing the fulcrum point of said pull tab for
enhancing the leverage thereof.
3. The improved pull tab mounting arrangement as
described in claim 2, wherein said fulcrum displacing means
comprises an expandable pleat formed in said attachment
means.
4. The improved pull tab mounting arrangement as
described in claim 3, wherein said attachment means comprises
a tiltable rivet structure.
5. The improved pull tab mounting arrangement as
described in claim 2, wherein said stress relieving means
comprises expansion means formed in said attachment means.
6. The improved pull tab mounting arrangement as
described in claim 5, wherein said expansion means expands
upon stressing thereby relieving stress loading of said
end panel and said tab.

7. The improved pull tab mounting arrangement as
described in claim 4, wherein said expansion means comprises
a single U-shaped pleat formed in said end panel.
8. The improved pull tab mounting arrangement as
described in claim 7, wherein said pleat is concentric with
and immediately adjacent to said rivet.
9. The improved pull tab mounting arrangement as
described in claim 8, wherein said pull tab has a nose portion
for fracturing said score line and said nose portion in pre-
opening position is held in spaced relation above and
radially inward of said score line.
10. The improved pull tab mounting arrangement as
described in claim 9, wherein said pleat comprises two con-
centric circular sidewalls depending from said end panel and
a substantially U-shaped bight portion connecting said
sidewalls, such that folding of that portion of said pleat
nearest said score line effects simultaneous unfolding of
that portion of said pleat most remote from said score line,
consequent to opening said container, results in displacing
said pull tab relative to said end panel.
11. The improved pull tab mounting arrangement
as described in claim 10, wherein said unfolded portion of
said pleat everts such that at least one sidewall of said
portion projects outwardly of the plane of said end panel
and said displacement of said tab brings said nose portion
into contact with said score line.

Description

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This invention relates to a container having a
portion of its wall weakened to serve as a tear strip
and having a tab attached to the tear strip to serve
as a lever for initiating the severing operation.
In general, the invention is directed to two
problems which have come to the fore with widespread
acceptance of this type of container. One problem is
to make it easier to lift the tab to initiate severance
of the tear strip. The second problem is to prevent
the unintentional fracturing of the opening score line
which may occur as the result of mishandling of the
container.
It is, therefore, one of the primary objects of
the present invention to provide an improved pull tab
mounting arrangement which will facilitate the opening
of a self-opening container. This is accomplished by
increasing the leverage afforded by the pull tab. More
specifically, the tab is mounted such that lifting of the
tab causes the fulcrum point to be displaced toward the
nose portion and away from the finger ring portion, thereby
providing the user an increase in mechanical advantage.
It is a further object of this invention to provide
an improved pull tab mounting arrangement which will reduce
the probability that mishandling of the container will
result in unintentional fracturing of the opening score
line. This is accomplished by mounting the tab such that
its nose portion is maintained in spaced relation with the
score line, thereby preventing minor displacements of the
tab from resulting in a score line fracture.
It is another object of this invention to provide
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an improved pull tab mounting arrangement which will permit
the use of thinner gauge metal in the fabrication of the
pull tab and end panel. This is accomplished by mounting
the pull tab so as to reduce the stress placed on these
memhers during opening. Specifically, the stress on the
end panel in the region immediately adjacent to the rivet
is reduced by the use of an expandable bellow which allows
controlled distortion of the metal in this area.
According to the present invention, there is pro-
vided an improved pull tab mounting arrangement for a self-
opening end closure for a can or similar container. The end
closure comprises an end panel, attachment means formed in
said end panel, a pull tab attached by said attachment
means to said end panel, and a score line formed in said ~
end panel and defining an opening flap therein. The improve- ~;
ment comprises unfoldable means for shiftably mounting said
attachment means in said end panel for relieving stresses
on said pull tab and said end panel during lifting move-
ments of said tab for opening of said container.
In drawings which illustrate one embodiment of the
present invention:
Figure 1 is a cross-sectional view of an end
closure with the improved tab mounting arrangement,
illustrating the unopened condition.
Figure 2 is a cross-sectional view similar to
Figure 1, illustrating the partially opened condition.
Figure 3 is a cross-sectional view of a conventional
end closure.
Figure 4 is a cross-sectional view similar to
Figure 3, illustrating distortion due to opening stresses.
In keeping with the present invention, there is
provided an easy-open end closure comprising a m0tal end
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panel 1, a rivet 2 integrally formed in said end panel and a
metal pull tab 3 fixedly attached to said end panel 1 by said
rivet 2. A score line 4 is formed in the end panel 1 and
defines an opening flap 5 therein.
In the standard easy-open closure (Figure 3), which
lacks a pleat 6, opening is accomplished by vertically
displacing the tab 3, thereby pivoting said tab 3 about said
rivet 1 and imposing a downward force on the tab nose portion
3a, said force resulting in the breaking of said end panel
1 along said score line 4 beneath said nose portion 3a.
Continued upward displacement of said tab 3 results in
controlled tearing of said end panel 1 along said score line
4, the opening flap 5 defined by said score 4 being bent
down and away from said end panel 1, thereby establishing
an opening in said end panel 1.
The fulcrum point 7 of the conventional easy-open
closure is located on the interface between the tab 3 and the
rivet head 2a at the point furthest between the tab 3 and the
3a. As the tab finger ring portion 3b is lifted, an upward
force is impressed on the rivet 2 and the end panel 1 in the
area immediately adjacent to the fulcrum point 7. This
stressing of the end panel 1 and the rivet 2 necessitates
the use of a thickness of metal with sufficient strength and
rigidity to resist deformation or tearing during opening of
the container. Further, this configuration minimizes the
length of the lever arm and maximizes the length of the load
arm and, consequently, places the maximum stress on the tab 3.
This necessitates the use of a thickness of metal for the
tab 3 which will resist bending during opening of the
container. The inefficient lever arrangement also results '~
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in the requirement o~ considerable ef-fort to lift the
tab 3 su~ficiently far to effect fracture of the score
line 4. ~ -
In the improved tab mounting arrangement of the
present invention (Figure 1) an expandable pleat 6 is formed
in the end panel 1 concentric with and immediately adjacent
to the rivet 2. The pleat 6 comprises two substantially .
parallel, concentric sidewalls 6a depending from the end
panel 1 and a connecting U-shaped bight portion 6b. The tab
nose portion 3a is held in spaced relation above and radially
inward of the score line 4, rather than in close contact with - ;
the score line as in the standard end closure. -
As the finger ring portion 3b is lifted, the pleat
6 unfolds everting outwardly with the unfolded sidewalls
6a projecting above the plane of the end panel 1 and causing -
displacement of the fulcrum point 7 radially outwardly
upwardly toward the score line 4 (Figure 2), thereby bringing
the nose portion 3a into close contact with the score line
4. After the pleat 6 has unfolded, the end closure is opened ;
in the conventional manner as described hereinabove. How- ;
ever, the fulcrum displacement has resulted in an increase
in the length of the load arm which in turn results in a
decrease in the stress loading on the tab 3 during opening
of the container. Further, the effort required to open
the container has been reduced.
The expansion of the pleat 6 also serves to
relieve the stresses on the rivet 2 and the end panel 1
by allowing controlled distortion thereof. These stress
reductions allow the fabrication of the tab 3 and the end
panel 1 from a thinner gauge metal.
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The improved pull tab mounting arrangement also
serves to reduce the probability that mishandling of the
container will result in an unintentional fracture of the
score line 4. In the conventional pull tab mounting
arrangement (Figure 3), the nose portion 3a rests in close
contact with the score line 4, such that an accidental
impact against the nose portion 3a may well result in an
unintended fracture of the score 4. In the improved pull
tab mounting (Figure 1), the nose portion 3a is held in
spaced relation above and radially inward of the score
line 4, such that an accidental impact against the nose
portion 3a will result in the nose portion 3a being forced ~.
downward into contact with the end panel 1, leaving the
score 4 unaffected. Further, such an accidental displacement
of the tab 3 will not interfere with the subsequent opening
of the container.
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