Note: Descriptions are shown in the official language in which they were submitted.
2l2639o
CONTAINER CLO~UR13 WITH EXTERNAL RIB8
Fi ~ld of the Invention
The present invention relates to injection
molded closures, and in particular, to such closures
S having deep plugs used in closing dairy containers
containing diary products.
~aclcground of the Invention
Many dairy products, such as cottage cheese,
sour cream, chip dip and the like are packaged in plastic
containers having a complementary plastic lid or closure
which engages with and seals the container. United
States Patents 4,826,039 and 4,872,586 disclose a
container closure that is injection molded and designed
to be used with the pre-existing conventional packaging
equipment that had been used with automatic filling and
capping equipment to place thermoformed closures onto the
filled plastic containers. The dairies that use this
equipment with thermoformed closures do want to replace
their existing filling and capping equipment merely to
switch from thermoformed closures to the injection molded
closures. The thermoformed closures or lids are made by
a die forcing a plastic sheet into the desired plug
configuration, which has an enlarged sealing bead
adjacent the bottom of the plug. The edges of the
thermoformed sheet are later rolled to form the closure
rim having a depending rim skirt with a generally
circular cross-section. These thermoformed lids are
nested in stacks from which they are dispensed. In the
stack, the edges of the adjacent rim skirts are spaced
from each other. That is, the outer skirts of the
thermoformed containers do not extend downwardly as far
as the plug portions. The nesting surfaces of adjacent
thermoformed closures hold closures with this space
between adjacent skirts; and it is into this space
-
212639
--2--
between adjacent skirts that a pair of mechanical fingers
ol ~ capping machine are inserted to remove the lowermost
c osure fr~m the stack. With closures of this type, it
is important that adjacent closures in the stack do not
become askew or tilted with respect to one another,
resulting in a relatively large gap between skirts on
adjacent closures on one side of the stack and little or
no gap between these adjacent closures on the other side
of the stack. The mechanical fingers employed in
automated packaging require generally uniform spacing
between adjacent stacked closures for successful
operation, and askew closures may cause obstruction of
the mechanical fingers, resulting in production
interruption and possibly equipment damage. United
States Patent 4,826,039 discloses a closure which, when
stacked, maintains adjacent, stacked closures level with
respect to one another, to provide generally uniform
spacing between adjacent closures about their periphery.
In this patented closure, a central panel of
the plug portion has a circular array of vertically
extending ribs projecting upwardly from the central
panel. If a closure begins to shift laterally relative
to another closure in the stack, it will be supported
against tilting by engaging supporting ribs on the
closure therebelow. More specifically lower nesting
surfaces on an offset in the upstanding sidewall of the
plug-like portion will engage ribs on the rim of the
closure therebelow. In this canted or inward position of
the top lid, the ribs supported the upper lid from
dropping further to the extent that caused its rim skirt
to close or to substantially narrow the gap or space,
into which the mechanical fingers need to move. If gap
or space was allowed to become too narrow, the mechanical
fingers would hit the inclined skirt wall and not remove
the lid. When the upper lid shifted inwardly and was
slightly canted enough to rest on the adjacent ribs of
2126390
--3--
the lower lid, the space between adjacent skirts was
still larce enough to accept the mechanical fingers.
Thus, the ribs functioned to prevent ^losure jamming.
It is preferred to support the closures in the
stack by the continuous, circular nesting surface on the
container rim rather than support a stack of closures on
the small, top edges of the ribs. It will be appreciated
that these closures are often shipped in large cartons
and that cartons may be placed on top of each, and
thereby cause a considerable downward force that would
tend to force the top edges of the ribs into the panel of
the overlying closure. Also, the closures should be
capable of withstanding a drop test simulating the
dropping of a carton full of stack closures, e. g.
simulating a drop of the carton from a truck or the like
for about four feet.
While the injection molded closures of the kind
taught by United States Patent 4,826,039 are commercially
successful and in widespread use, the ribs on the top
panel were annoying to people who picked up the closures
two at a time with their hands and cut their fingers on
the sharp, top edges of the ribs. It sometimes occurs in
the dairy that a small short run will be capped manually
by workers using their hands to place the lids onto the
containers. In other instances, the capping machine may
not have successfully capped the container with a
closure, and a person will manually place a closure on
that container to manually cap the closure. Persons who
handled these closures wore leather gloves in some
instances or put bandages on their fingertips to prevent
their fingertips from being cut by the sharp, upper edges
of the ribs. While the sharp edges of the ribs could be
blunted to prevent cutting of fingers, the ribs still
suffered the shortcoming of being potential dust
collectors.
2~2~3go
Furthermore, the ribs on the upper closure
surface may detract from the aesthetic appearance of the
closure and make i~ difficult to print onto the closure.
The ribs on the upper closure surface also make it
difficult to wipe spillage off of the closure surface.
It is desirable to provide a closure which can
be formed by injection molding and having means for
preventing both jamming of adjacent closures, with the
closure also providing a smooth upper closure panel to
facilitate wiping away of spillage on the closure and
providing good aesthetic appearance to the consumer.
8ummary of the Invention
In accordance with the present invention, an
injection molded plastic closure for dairy products is
formed with a plurality of peripherally spaced, integral
anti-jamming ribs on its underside. The anti-jamming
ribs of a given stacked closure will contact the upper
surface of the closure therebeneath when the overlying
lid shifts laterally from its fully nested position, with
the ribs being configured in a manner which maintains
generally uniform spacing between adjacent stacked
closures about their periphery and maintains adjacent
stacked closures level with respect to one another. That
is, the ribs preventing a wedge-type of locking
engagement between adjacent lids and a riffling of the
stack when a lid is askew, will generally cause a
self-centering of the askew lid with the rest of the lids
in the stack.
In accordance with the preferred embodiment of
the invention, the closure comprises an encircling upper
rim surface and a recessed central circular panel or
disk, with a sidewall extending between the upper rim and
the central panel which sidewall has offset portion
radially inwardly of the rim to the recessed central
circular panel. The double step-down sidewall comprises
2l26~9o
an upper vertical annular wall section, a horizontal
annular shelf, and a lower vertical annular wall section.
The upper annular wall section depends vertically
downwardly from the inner edge of the annular upper rim,
and terminates at the horizontal annular shelf. The
horizontal annular shelf extends radially inwardly from
the lower end of the upper annular wall section and
terminates at the lower annular wall section. The lower
annular wall section depends vertically downward from the
inner edge of the horizontal shelf and terminates at the
central circular panel or disk. Thus, the double step-
down of the sidewall from the upper rim to the central
circular panel recesses the circular panel with respect
to the upper rim to define an upwardly facing cavity.
The sidewall and circular panel form the plug-like
section of the lid to be received.
A peripheral skirt extends downwardly from the
radially outward edge of the annular upper rim, with the
skirt having a radially inward retention bead near its
lower end. The container to which the closure is applied
has a radially outward retention bead at the upper end of
its sidewall. Upon application of the closure with the
container, the upper end of the container is received
between the peripheral skirt and the upper annular wall,
with the radially outward bead at the upper end of the
container sidewall sliding below and engaging the
underside radially inward ~ead of the closure skirt to
retain the closure with the container.
For the purpose of preventing the jamming of
lids and to keep the lids centered in the stack, a
plurality of peripherally spaced rib means extend
radially outwardly from the underside of the closure
sidewall and have an upper closure-engaging surface for
contact with the encircling rim upper surface of another
closure therebelow and have a lower closure-engaging
surface for contact with the lateral shelf of said other
2126391~
-
--6--
closure therebelow. The ribs prevent the lower sidewall
portion of a closure from sliding down into wedged
engagement with the lower sidewall poi-tion of another
closure therebelow.
S In accordance with a preferred embodiment of
the invention, the intersection of the lateral shelf and
lower sidewall portion is arcuate to define a lower
self-aligning surface, and the outward end of the lower
closure-engaging surface is arcuate to define an upper
self-aligning surface. When two closures are in
non-centered stacked relation, the upper self-aligning
surface of the upper closure, which surface is defined by
the ribs, bears or cams against the lower self-aligning
surface of the lower closure, which surface is defined by
the closure sidewall, to facilitate self-centering of the
closures with respect to one another particularly when
the stack is rifled in order to provide the force to
realign-the non-centered lids.
Brief De~cription of the Drawings
In the drawings, wherein like elements are
referenced alike:
FIG. 1 is a perspective view of a closure
embodying various features of the present invention,
shown spaced from a container;
FIG. 2 is an elevational view of the underside
of the closure of FIG. 1;
FIG. 3 is an enlarged, fragmentary
cross-sectional view of the closure taken along line 3-3
of FIG. 2;
FIG. 4 is a fragmentary cross-sectional view of
two closures embodying various features of the present
invention, shown in askew stacked relation;
FIG. 5 is a fragmentary cross-sectional view of
two closures embodying various features of the present
invention, shown in properly stacked relation; and
2 1 ~C~ ~
FIG. 6 is a view similar to FIG. 3 with the
closure applied to the container rim.
Detailed DescriPtion of the Preferred Embo~iments
A closure embodying various features of the
present invention is illustrated in FIGS. 1-5 and
referred to generally by reference numeral 20. The
closure 20 comprises a central, plug-like portion with a
recessed central circular disk or panel section 22.
Encircling the plug-like portion is an encircling annular
upper rim 24, with a sidewall 26 extending between the
upper rim 24 and the central circular panel 22.
The sidewall 26 is offset, or stated
differently, steps down radially inwardly of the rim 24
to the recessed central circular panel 22. The preferred
embodiment is a step-down sidewall 26 which comprises an
upper annular, vertical sidewall section 28, a lateral
offset annular shelf 30, and a lower annular, vertical
sidewall section 32. In the illustrated embodiment of
~IGS. 1-5, the upper annular sidewall section 28 depends
vertically downwardly from the inner edge 34 of the
annular upper rim 24, and terminates at the lateral
offset annular shelf 30. The lateral offset annular
shelf 30 extends radially inwardly from the lower end 36
of the upper annular sidewall section 28 and terminates
at the lower annular sidewall section 32. The lower
annular sidewall section 32 depends vertically downwardly
from the inner edge 38 of the lateral offset shelf 30 and
terminates at the central circular panel or disk 22.
Thus, the step-down of the closure sidewall 26 from the
upper rim 24 to the central circular panel 22 recesses
inwardly the circular panel 22 with respect to the upper
rim 24 to define an upwardly facing cavity 40.
For the purpose of retaining the closure on the
container, the closure has a peripheral skirt 42 which
depends downwardly from the radially outward edge 44 of
2 12639
--8--
the annular upper rim 24, with the skirt 42 having a
radially inward retention bead 46 near its lower end 48.
The container 50, to which the closure is
applied, has a radially outward bead or projection 52 at
the upper end 54 of its container sidewall 56, which
defines an open mouth. Upon application of the closure
20 to the container 50, the upper end 54 of the container
50 is received between the peripheral skirt 42 and the
upper annular sidewall portion 28 of the closure 20, with
the radially outward bead 52 at the upper end 54 of the
container sidewall 56 engaging with the radially inward
retention bead 46 of the closure skirt 42 to retain the
closure 20 on the container 50 in a generally sealed
relationship. As best seen in FIG. 6, the retention bead
lS engages the upper sidewall portion 28, the upper rim 24
and the skirt 42 to seal the container contents against
leaking from the container. The closure sidewall 26 and
circular panel 22 define a plug-like section, referred to
generally by reference numeral 58, which is received in
the open mouth of the container 50 for sealing engagement
with the container sidewall 56.
There is a need for the closures 20 to have an
anti-jamming feature or means that prevents the stacked
closures from jammed, as shown in the left portion of
FIG. 4 in which the left end of the upper closure has
slid inwardly sufficiently that the skirt 42 on the upper
lid has dropped to engage the rim of the underlying lid,
thereby eliminating the space or gap 72 (FIG. 5) into
which the mechanical fingers of the automatic capping
apparatus must move. With the closure in the position
shown in FIG. 4, the mechanical finger will hit the
depending skirt 42 of the upper closure and cause a
jamming, and a consequent failure to remove the lower
closure and probably subsequent closures on the continual
cycling of the capping apparatus. While the closures of
the kind disclosed in aforementioned patent had
2l2639o
anti-jamming ribs, these were positioned to cause cuts on
the fingers when handled manually, and to collect dust.
In accordance with the present invention, there
is provided a anti-jamming means which prevents the
jamming of lids and keeps the lids centered and with
their peripheral skirts 42 spaced apart to provide a
large enough gap 72 into which the mechanical fingers may
be inserted. Herein, the anti-jamming means is in the
form of ribs 62 which are formed on the lower, outer
lo peripheral surface of the plug-like portion. As shown in
FIG. 6, the ribs 62 will be disposed on the underside of
closure and hidden down within the container when the
closure is applied. This is in contrast to the patented
closure in which the ribs are exposed at the top side of
the panel.
A plurality of peripherally spaced ribs or rib
means 62 extend radially outwardly from the closure
sidewall 26. The rib means 62 are preferably narrow ribs
or tabs, which require relatively little additional
plastic. As best seen in FIG. 5, the rib means 62
preferably include an upper closure-engaging surface 64
which contacts the upper end 34 of the upper sidewall
portion 28, or the upper surface 66 of the annular
encircling upper rim 24 (which is integral with the upper
end of the closure sidewall), of another closure 20
therebelow when two closures 20 are properly stacked.
The rib means 62 preferably further include a lower
closure-engaging surface 68 which contacts the upper
surface 70 of the lateral shelf 30 of the other closure
20 therebelow when the two closures 20 are stacked. The
upper surface 70 of the lateral shelf 30 thus serves as
an upper nesting surface on which the lower
closure-engaging surface 68 of the rib means 62 rests or
nests to prevent wedged engagement of the closure with
another closure therebelow.
2l26~o
--10--
As best seen in FIGS. 1-3, the rib means 62 of
the preferred embodiment is shown as a narrow rib
integral with both the outer surfaces of the lower
sidewall portion 32 and lateral offset portion 30 of the
closure sidewall 26. The rib means 62 extend radially
outwardly from the outer surface 71 of the lower sidewall
portion 32 of the closure 20 and depend downwardly from
the lower surface 73 of the lateral offset portion 30.
The lower closure-engaging surface 68 of the
rib means 62 preferably extends radially outwardly from
the outer surface 71 of the lower sidewall portion 32 and
co-planar with the lower surface 75 of the central
circular panel 22. Thus, the lower closure-engaging
surface 68 of the rib means 62 is essentially a narrow
outward continuation of the lower surface 75 of the
central circular panel 22. The outwardmost end 74 of the
lower closure-engaging surface 68 of the rib means 62 is
preferably rounded or arcuate for self-aligning reasons
which will be explained in detail further below.
The upper closure-engaging surface 64 of the
rib means 62 is preferably horizontal and is spaced
downwardly from the lower surface 73 of the lateral
offset portion 30 of the sidewall 26. The outermost
upper edge 76 of the rib means 62 is preferably
coextensive with the outer surface 78 of the upper
sidewall portion 28. That is, the outermost upper rib
edge 76 preferably depends vertically downwardly from the
lower surface 73 of the lateral offset portion 30 of the
closure sidewall 26, not extending outwardly beyond the
outer surface 78 of the upper sidewall portion 28. The
outer surface 78 of the upper sidewall portion 28 bears
against and has a sealing engagement with the inner
annular wall surface of the container mouth. Extension
of edge 76 outwardly beyond the outer surface 78 of the
upper sidewall portion 28 would result in interference
- 2i26~
--ll--
with the upper end 54 of the sidewall 56 of a container
S0 when the closure 20 is engaged with the container.
The rib means has a tapered intermediate
section 80 which extends at an angle from the upper
closure-engaging surface and tapers inward to the rounded
outwardmost end 74 of the lower closure-engaging surface
68. Thus, the lower closure-engaging surface 68 is
offset laterally and offset vertically from the upper
closure-engaging surface 64. The rounded edge 74 and the
tapering of the intermediate section 80 facilitates
self-aligning of stacked closures, as will be described
further below.
Referring again to FIG. 5, it can be seen that
the rib means 62 serve to maintain the gap 72 between the
peripheral skirts 42 of an upper and lower closure 20 in
properly stacked relation. The rib means are designed so
that the gap 72 can accommodate the mechanical fingers of
automated packaging equipment which automatically remove
a closure 20 from the stack. It is important that the
closures 20 be maintained in stacks in a manner which
allows the ready release and handling of a closure by the
packaging equipment. In this regard, it is important
that there be adequate spacing maintained between the
lower end 48 of the skirt 42 of an upper closure and the
upper surface 66 of the annular encircling upper rim 24
of another closure 20 therebelow. Furthermore, this
adequate spacing must be maintained about the entire
periphery of the closures.
When two closures 20 are properly stacked, as
illustrated in FIG. 5, the requisite spacing between
closures, about their periphery, is maintained. With the
closures centered with respect to one another, it is
preferable that the upper sidewall portions 28 of
adjacent closures are in columnar loading, and the ribs
are not necessary. The lower end of the lower sidewall
portion 32 of the upper closure 20 rests on the upper end
- 212639~
-12-
of the lower sidewall portion 32 of the lower closure.
With the vibrations and handling associated with
automated packaging equipment, two closures may try to
become slightly off-center with respect to one another.
One problem associated with stacked closures is
that the downward pressure exerted on a lower closure 20
by a stack of closures thereabove sometimes causes the
sidewall 26 of the lower closure 20 to be flexed radially
outwardly to form a larger diameter section which allows
the plug section 58 of the closure thereabove to drop
down into the enlarged cavity 40 and to become wedged or
jammed therein. The closure sidewalls 26 are relatively
thin in thickness and quite wide in diameter, and are
pliable because of this diameter, the thin wall thickness
thereat, and the low density polyethylene material
commonly employed.
Without the anti-jamming ribs 62, some
particularly bad jamming of closures in a stack could
occur. For instance, if the sealing surface 87 on the
outer surface of the upper section 28 of the sidewall 26
of an upper closure was to wedge against the lower
interior surface of the lower section 32 of a lower
closure in the stack, this jamming would not only prevent
the mechanical fingers from moving into a non-existent
gap 52 between adjacent closure skirts but also would
wedgingly lock the closures to each other and thus, be
difficult to realign. The anti-jamming ribs 62 prevent
this wedging interlock and also serve to easily realign
the closures in the stack. If, when loading a stack of
closures into the automatic capping machine's magazine,
it is noticed that some of the closures are askew within
the stack, the operator will run his hand along the edge
of the stack raising and lowering the closures relative
to one another, i.e., a riffling of the stack, whereupon
the ribs 62 on one closure cam against the adjacent
closure to realign the askew lid within the stack.
2l26~9o
The rib means 62 prevent the plug section 58 of
the closure thereabove from dropping down into the cavity
40 of the closure therebelow and thus prevents the
closures from becoming wedged or jammed together. More
specifically, the rib means 62 prevent the lower sidewall
portion 32 of the closure 20 from sliding down into
wedged engagement with the lower sidewall portion 32 of
another closure 20 therebelow, and prevent the upper
sidewall portion 28 of the upper closure 20 from wedging
lo against the upper sidewall portion 28 of the lower
closure.
Absent the rib means 62 of the present
invention, upon the closures becoming off-center, the
lower sidewall portion 32 of the upper closure 20 would
slide off of the annular shelf 30 of the next lower
closure 20, with the lower sidewall portions 32 of the
closures abutting one another and closing the gap 72
between rims of adjacent closures. The rib means 62,
extending outwardly beyond the lower sidewall portion 32,
prevent this jamming. That is, with the stacked closures
20 slightly off-center and the lower sidewall portion 32
of the upper closure slid, say, inwardly of the lower
sidewall portion 32 of the lower closure, the lower
closure-engaging surface 68 of the rib means 62 would
still be supported upon the upper surface 70 of the
lateral offset portion 30, thereby preventing downward
movement of the upper closure, and thus precluding
jamming together of the closures.
However, with greater off-centering of stacked
closures, such as illustrated in FIG. 4, the lower
closure-engaging surface 68 of the rib means 62 may be
slid inwardly of the lower sidewall portion 32 of the
lower closure 20, as in FIG. 4. To facilitate self-
centering of the upper closure 20 from the position of
FIG. 4 to the position of FIG. 5, the outwardmost end 74
of the lower closure-engaging surface 68 is rounded, and
2 12G390
-14-
the inner edge 38 of the lateral offset portion 30, at
which the lower sidewall portion 32 and lateral offset
portion 30 intersect, is also rounded at its inner edge
38. Hence, in this off-center position, rounded end 74
of the rib means 62 bears against rounded end 38 of the
offset portion 30, with both rounded surfaces acting as
mutual camming surfaces which bear against each other and
a force applied to the stack allows the askew closure to
be cammed into a centered alignment.
More specifically, with reference to FIG. 4,
when the upper closure 20 shifts to the right, the left
side of the closure drops down slightly with rounded
surfaces 74 and 38 bearing against one another as
described above. Simultaneously, the right side of the
closure is shifted upwardly and to the right with the
rounded end 74 of the rib means 62 on the right side of
the upper closure being moved to a position at which it
bears against the inner edge 34 of the annular upper rim
24. The weight of the upper closure, in addition to the
weight of any further closures stacked thereabove, acts
downwardly on the right side of the upper closure. The
provision of the rounded end 74 on the rib means 62
provides a smooth bearing or camming surface against
which the inner edge 34 of the rim 24 slides to allow the
rib means 62 to slide downwardly and inwardly to its
properly centered position. This movement on the right
side of the closure 20 results in outward pushing of the
rib means 62 on the left side of the closure 20. The
rounded edge 74 of the left side rib means then bears
against the rounded inner edge 38 of the lateral offset
portion 30 of the lower closure which allows the left
side of the upper closure to slide upwardly and outwardly
to its centered position, as illustrated in FIG. 5.
By way of example only and not of limitation,
closures were constructed having sixteen rib means 62
spaced uniformly about the external periphery of the
- 212639o
closures. The outwardmost end 74 of the lower closure-
engaging surface 68 of each of the rib means 62 was
round~d, having a radius of curvature of 0.025 inch. The
inner edge 38 of the lateral offset portions 30 was also
rounded, having a radius of curvature of 0.045 inch.
These radii were found to attain the desired self-
leveling and self-centering effect, and no jamming
problems occurred during tests of these closures. Tests
were also run with closures having eight rib means, but
such closures were found to be inferior to those having
sixteen rib means. Better top-load support and very
little side or lateral movement was realized with sixteen
rib means as compared with embodiments having only eight
rib means.
The tapered intermediate section 80 of the rib
means 62 still further facilitates this self-centering
and self-leveling. When the upper closure is more
severely off-center, the rounded outwardmost end 74 of
the lower closure-engaging surface 68 is moved inward of
inner edge 38 of the lateral offset portion 30, as shown
in FIG. 4. Thereupon, it is the intermediate rib section
80 which bears against edge 38, rather than the rounded
end 74. With the intermediate rib section 80 tapered, as
illustrated, there is an upward force component urging
the upper closure 20 back to its centered position,
whereas if the intermediate section 80 were vertical,
there would be no such upward force component, and the
closures would remain askew.
With the rib means 62 being small and residing
on the underside of the closure 20, the aesthetic
appearance of the closure is enhanced as compared with
closures having ribs on their upper ends. Since with
this design there are no ribs at the upper surface of the
central circular panel 22, this design allows for
printing over the entire upper surface of the central
panel. Also, the elimination of rib means from the upper
2126390
-16-
central panel 22 allows for easier clean-up of spillage
onto the closure. Still further, the elimination of rib
means from the upper surface of the central panel 22
allows factory packaging workers as well as consumers to
press down on the top of the closure 20 to seal a
container S0 without concern for the rib means cutting or
scratching their fingers, which is currently a common
complaint of packaging workers.
The closure 20 of the present invention lends
itself to production by injection molding, and thus lends
itself to inexpensive production.
While only specific embodiments of the
invention have been described and shown, it is apparent
that various alterations and modifications can be made
therein. For instance, the shape and number of the rib
means 62 may be altered to suit the specific requirements
of a given application without departing from the
inventive concepts of the invention. It is, therefore,
the intention in the appended claims to cover all such
modifications and alterations as may fall within the
scope and spirit of the invention.
