Note: Descriptions are shown in the official language in which they were submitted.
2121279
This invention relates to a tamper resistant
closure for use on a container and to a method of
manufacturing a core of a mold to form screw threads of a
closure made up of elongated bubbles.
For safety and security reasons, tamper
resistant closures are known. One such previous closure
is described in European Patent Application Number
90310078.2 published on April 10th, 1991. The closure in
that Application has a tamper evident band having a
movable flange thereon with the band being connected to
the closure along a weakened line. The weakened line can
be formed by scoring or by circumferentially-spaced
bridges. When the closure is installed on the container,
the flange and tamper evident band override a ring on the
container. When the closure is desired to be removed,
sufficient force must be exerted on the closure 'o sever
the tamper evident band and flange from the rest of the
closure along the weakened line. A disadvantage of this
closure is that the weakened line must be designed within
a very fine tolerance, one that is not always
satisfactorily achieved during manufacture.
PCT Application No. US 91/05434 published on
March 5th, 1992 describes a tamper indicating closure
having a retaining hoop with relief windows extending
from a hinged edge at least one-third of the distance
toward a free edge. The windows are located to interrupt
the hinged edge and create a series of spaced hinges
around the circumference of the closure. The windows are
located along the hinged edge so that the retainer can be
moved from an outward molded position to an inward
installation position much more easily so that the
retainer does not have to be moved between the two
positions by a separate step. With the present
invention, t~e windows are spaced from the hinged edge.
In Car.adian Patent No. 1,182,782 issued on February l9th,
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1985, there is described a closure and container with
screw threads made up of a series of projections in the
shape of truncated cones so that the screw threads of the
closure and container can interlock with one another.
The projections were made by drilling successive holes
into a core for use in a mold. The separate drilling of
each hole can be extremely time consuming particularly
when the spacing between holes and the depth of each hole
must be ident~al.
It is an object of the present invention to
provide a tamper resistant closure having a tear strip in
combination with a flange hinged onto a tamper evident
band where the flange has windows located therein so that
the flange can be manufactured with an extremably small
or even negative tolerance relative to a ring of a
container and still be made to fit over said ring during
installation without severing the tear strip.
It is a further object of the present invention
to provide a method of manufacturing a core for a ~.old
where the core contains depressions to create a screw
thread in a closure where the screw thread is a series o~
elongated bubbles located end to end.
A tamper resistant closure is used on a
container having a neck surrounding an opening said necX
having external threads thereon, said neck having a ring
located beneath said threads when the container is in an
upright position. The closure has a central portion
having a periphery with a skirt extending from said
periphery, a tear strip extending from said skirt, a
tamper evident band affixed to said tear strip and a
movable flange extending from said band. The tear strip
is affixed to said skirt by severable attachment means.
The skirt has an interior surface with threads thereon
corresponding to the threads on said container. The
flange is co~,nected to said band by hinging means so that
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said flange extends inwardly relative to said band an.d a
free edge of said flange is movable between an upper
position and a lower position. The flange has a
plurality of spaced windows located therein, said windows
S being spaced fr~m said hinging means and being
substantially centrally located between said hinging
means and said free edge. The central por~ion, skirt,
strip, band and flange are sized to fit snugly on said
neck so that when the threads of the neck are engaged
with the threads of the closure, the closure is in a
closed position relative to said container. The free
edge of said flange is located above said hinging means
and beneath said ring. The flange overrides said ring as
the closure is installed on said container. The flange
engages said ring when the closure is attempted to be
removed from said container to prevent said flange from
overriding said ring, said band and flange being
detachable from said skirt by manually seve.ing said
attachment means to remove said tear strip.
A method of manufacturing a core of a mold to
form screw threads made up of elongated bubbles located
end to end, said core having a cylindrically-shaped outer
surface thereon, said method using a ring-shaped
electrode having a cylindrically-shaped inner surface
thereon, said electrode being sized to fit over said
cylindrically-shaped outer surface of said core, with
equally-spaced contact points on said inner surface, said
electrode being connected to a high voltage source and
mounted in an electrical discharge machine, there being a
contact point on said inner surface for each bubble to be
formed in said screw thread, contacting one contact point
of said electrode for every two vertically spaced bubble-
shaped depressions that are to be cut into said core,
said method comprising moving the electrode such that one
contact point contacts said outer surface at a time to
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burn at least one bubble into said outer surface, moving
the electrode so that a second contact edge cuts at least
one more bubble into said ou~er surface, repeating this
process until each contact poir.t around the circumference
of the electrode contacts an outer surface of said core
to burn oblong bubble shapes into said core so that said
bubble shapes form a screw thread around said core from
end to end, each contact edge cutting two vertically
aligned bubbles where parts of the screw threads are to
be vertically spaced from one another.
In the drawings:
Figure 1 is a perspective view of a closure and
a container where the closure has a bubbled screw thread
and a flange with windows thereon;
Figure 2 is a partial perspective view of a
bubbled screw thread;
Figure 3 is a partial front view of a bubbled
screw thread;
Figure 4 is a partial perspective view of a
closure with a flange exte~ding upward;
Figure 5 is a partial perspective view of a
closure with a flange extending downward;
Figure 6 is a perspective view of an electrode
and core spaced apart from one another;
Figure 7 is a schematic top view of an
electrode and core in one ~osition;
Figure 8 is a schematic top view of the
electrode and core in a different position from that
shown in Figure 7;
Figure 9 is a schematic top view of the core
and electrode in a different position from that shown in
Figures 7 and 8; and
Figure 10 is a cross-sectional view of a
further embodiment of a closure and part of a container
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where a tear strip and tamper evident ~and are one
component.
In Figure 1, a closure 50 is located above a
container 4. The container 4 has a neck 6 with
conventional external screw threads 8 thereon. The neck
6 has a ring 10 located beneath the threads 8 when the
container is in an upright position as shown in said
Figure. The closure 50 has a central portion 52 with a
periphery 54 and a skirt 56 extending from said
periphery. A tear strip 58 extends from the skirt 56 and
a tamper evident band 60 extends from the tear strip 58.
A movable flange ~2 extends from the band 60. The tear
strip 58 is affixed between the skirt 56 and the band 60
by severable attachment means, being a plurality of
severable tabs 64. On the flange 62 are a plurality of
spaced windows 66. The skirt 56 has an interior surface
68 with screw threads 70 thereon. The screw threads 70
can be one continuous screw thread or can be several
partial threads or any suitabie combina~io~ in between.
The screw thr~ads 70 are made up of a plurality of
elongated bubbles 72 that are located end to end to one
another to form a screw thread. With conventional
threads, when installing plastic closures on plastic
containers using a capping machine, and particularly, a
high speed capping machine, there is a large amount of
dusting produced from the corresponding screw threads on
the closure and container during installation. Dusting
refers to fine particles of plastic that break free from
the closure and/or the containers due to friction during
installation of the closure. Dusting is still a serious
problem whether the container is made of glass or
plastic. Particularly when the container is used for
food, the amount of dusting from conventional screw
threads has been found to be unacceptable. With the
elongated bubble threads 70 of the pre~ent invention, the
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amount of dusting that occurs is reduced by approximately
75~ over conventional screw threads.
In Figures 2 and 3, the shape of the
bubbles 72 can be seen more clearly. From Figure 3 it
can be seen that the bubbles 72 are relatively flat on a
bottom 74 and rounded outward on a top 76. Generally,
the bubbles can be described as having a curved oblong
surface (the cross-section of which is shown in Figure
10) with rounded edge. The edges are not 90~ as shown in
Figures 2 and 3.
In Figures 4 and 5, there is shown an
enlarged partial perspective view of the flange 62 and
tamper evident band 60. The flange 62 is connected to
the tamper evident band 60 by hinging means 78. From
Figure 4, it can be seen that the flange 62 has a
plurality of equally spaced windows 66 located therein.
The windows 66 are spaced apart from the hinging means 78
and are generally substantially centrally located between
the hinging means 78 and an inner edge 80 of said flange.
The position of the flange 62 shown in Figure 4 is the
approximate position of the flange when it is installed
beneath the ring 10 of the container 4. In Figure 5, the
flange has been moved further apart from the tamper
evident band 60 to expose an interior surface 82 of said
flange. It can be seen that there are two lateral ribs
84 located between each window 66. The purpose of the
lateral ribs 84 is to provide lateral strength to the
flange 62 so that it will not bend laterally once it is
installed on a container. If a flange were to bend
laterally, it would be possible to turn the closure off a
container without severing the tabs 64. The purpose of
the windows 66 is to provide longitudinal flexibility to
the flange 62 so that the inner edge 80 can be stretched
over the ring 10 even though an inside diameter of the
flange 80 when the flange is in a rest position is
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smaller than an outside diameter of the ring 10. Thus,
it can be seen that the flange 62 can be stretched
relatively easily over the ring 10. The flange 62 could
be designed with only one ridge located between each
window rather than two ridges. ~he windows can be
completely open or they can be closed with a thin film of
plastic or other closure material.
In Figure 6, there is shown an electrode 86
located above a core 88. The electrode 86 has a
plurality of contact points 90. The contact points gO
are located on vertical edges 91. An inside diameter of
the contact points 90 is slightly larger than an outside
diameter of the core 88 so that an outer surface 92 of
the core 88 can fit within the electrode 86. The
electrode 86 is mounted into a conventional electrical
discharge machine (not shown) and a high voltage is
ap lied to said electrode. The core 88 is mounted within
the electrode 86 with the surface 92 adjacent to the
contact points 90. When it is desired to create two
bubble forming grooves verti~ally apart from one another,
there are two contact points 90 located vertically apart
from one another on the same vertical edge 91.
As shown in Figures 7, 8 and 9, the electrode
86 is moved slightly relative to the core 88 so that one
of the contact points 90 of the electrode 86 contacts the
outer surface 92 of the core 88. In the portion of the
outer surface 92 shown in Figure 6, there are two rows of
grooves 94 in the shape of inverted elongated bubbles
arranged end to end to form a screw thread. As each
contact point contacts the outer surface 92, one groove
for one inverted elo~gated bubble for each row is burned
in~o the core 88. The contact points 90 are 5~ apart
from one another and the electrode 86 is therefore moved
5~ at a time relative to the core 88 until all of the
contact points around the electrode 90 have successively
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contacted the o~er surface 92 of the core 88. The
distance of movement shown in Figures 7, 8 and 9 is
greatly exaggerated to approximately 1200 between each
figure as a 5~ distance would not be noticeable.
Depending on ~he size of bubbles that one wished to
create, the distance between contact points on adjacent
edges could be more or less than 50. From Figure 6, it
can be seen that the grooves 94 are relatively flat on a
bottom and rounded outward on a top so that when the core
is used in a mold to form the closure with the elongated
bubbled screw threads, the screw threads can be removed
from the core ~ithout damaging them. The core is then
used in a conventional molding machine to form a closure.
The closure is placed into a bending machine to rotate
the flange to an inward position.
In Figure 10, in a further embodiment of the
invention, a closure 96 is identical to the closure 50
shown in Figure 1 down to the tear strip. With the
closure 96, the tear strip and tamper evident band are
combined into one component so that when the tear strip
is pulled, the band and tear strip are removed along with
the flange 62. The tear strip/band 98 has a handle 100.
When the handle is pulled, tabs 64 are severed and the
tear strip band 98 pulls away from the skirt 56.
Preferably, though not shown in Figure 10, approximately
the last approximately 10~ in circumference of the tear
strip band 98 is affixed to the skirt so that an end of
the band 98 opposite to the handle 100 remains affixed to
the skirt to discourage a user from discarding the band
98 separately from the skirt. This feature will reduce
pollution caused by discarded bands. If a user wishes to
tear the band completely off the skirt, he or she will be
able to do so by cutting it off or by applying an
appropriate force. The sectional view of the screw
thread 70 shows the cross-sectional shape to a centre of
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bubbles 72. It can be seen that the upper surface of
each bubble 72 is rounded outward relative to the lower
surface of each bubble. It can also be seen that edges
of the bubble are rounded. Where the cross-sectional
shape, shown in Figure 10, differs from the shape of the
bubbles 72 shown in Figures 1 and 2, the shape in Figure
10 is the preferred shape. Further, the cross-sectional
shape of the ring 10 and of the standard screw thread 8
of the container 4 are also shown.
The present invention has a
significant advantage over previous tamper resistant
closures in that the use of the hinged flange 62 allows
variations in the relative size of the closure and
container within acceptable tolerances. Also, the tabs
64 can be made with a great deal of strength. This
strength can be increased by increasing the number or
size of the tabs 64. Since the tabs 64 are severed by
manually pulling the tear strip 58, the tabs 64 are
severed one at a time, if the two sets of tabs are
alternated or, if the two sets of tabs are vertically
aligned with one another at the rate of two at a time.
With previous tamper resistant closures using the hinged
flange 62 and tabs or a scored line, the removal of the
closure requires that all of the tabs or the entire
scored line be severed virtually simultaneously.
Sometimes, a great deal of strength is required to sever
the tabs or the scored line. With the present invention,
the tabs can be severed easily, singly or in pairs, while
always providing more than sufficient strength to ensure
that the tabs do not sever prematurely during the initial
installation of the closure on the container or during
shipping and handling. The present invention permits a
broad range of design relating to the strength of the
tabs.
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Further, the windows permit the flange of the
closure to be designed with an inside diameter
significantly smaller than an outside diameter of said
ring on the container. This is particularly important
for large closures (for example, those having a diameter
greater than 7 cm). By giving the flange greater
flexibility, the windows enable the capping machine to
differentiate between the torque required to turn the
closure onto the container over the ring and the final
torque required to tighten the closure. The torque
required to turn the closure over the ring is no more
than 75% of the final torque. Further, when the
container is made from plastic material rather than from
glass, the container will flex somewhat and it is even
more important to size the closure within very close
tolerances relative to the container. In addition, the
bubble threads can greatly reduce dusting to acceptable
levels. Bubble-shaped screw threads can also be used on
the container.
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