Note: Descriptions are shown in the official language in which they were submitted.
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I CONTAINER SEAL TESTING METHOD AND SYSTEM
AND TEST~E~LF~ CONTAINER STRUCTURE
; sackqround of the Invention
Field of the Invention
The present invention relates to the testing of the
. integrity of the seal securing a container lid or closure on a
container body and a container structure whose seal is adapted
to be tested.
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Description of the Related Art
At the present time comestibles such as yogur~, ¦
cheese spread or other perishable items, are often packed in
containers of various types, such as bowls, trays and other
containers which are opened by peeling off their lids. The
containers may have any shape and configuration, for example,
cylindrical, rectangular, oval, oblong, etc. One type of
container has a bowl-like body, a bottom wall and a flexible
lid.
The lid usually is, but need not be a multl-layer
sheet or laminate, pre erably flexible in the form of a thin,
flexible disc. The lid may consist of layers of p'as_ic which
are laminated on opposite sides of a layer o' aluminum foil.
The bottom layer of the lid is usually a heat-sealable or
adherable plastic. The cont.ainer body is filled and its lid
is placed on a top surface usually the flange, of the
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¦l container body. The outer peripheral portion of the lid, at
its bottom face, is hermetically sealed or adherecl to the
I flange.
¦ If the lid-flange seal has even a tiny hole, void or
I interruption micro-organisms may enter the container and spoil
¦l the food or other perishable product. Such spoilage may cause
¦i consumers to reject the brand of the product in the future.
Il The consumer may resent having the inconvenience of discarding
¦¦ the container or returning it to the store. In addition, the
- li spoiled food, if eaten, may cause illness, and may also
~I seriously damage the reputation of the manufactu_er and/ox
j~ food producer or packer.
i! Food manufacturers are aware of the danger of
, spoilage due to seals which are not hermetic, and seek to
i prevent such faults by quality inspection of their filled
i containers. Generally, such quality inspectlon in the case of
high acid food products includes testing for faulty seals by
~; pulling a few containers from the production line and visually
testing them for leakage. That type of quality control, based -
on a statistically meaningful random sample, is well adapted
to detect machine errors which cause faulty seals on all the
containers in a product~on run. However, statistical quality
control is not well adapted to detect random faulty seals, for
example, a pin hole in the seal of one container out of a
1~ production run of 10,000 containers.
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It is reali~ed that it would be preferable for high
I acid foodstuffs and it is generally required for low acid
l sterilized, i.e., retorted shelf-stable foodstuffs, to test
i each and every container, which is called ~100~ testing~. The
ideal is to test each container twice, called "200~ testing".
Such testing for retortable containers would preferably be
accomplished before and after the filled, sealed container and
¦ its contents are sterilized. For filling, sealing and packing
.! operations high speed is preferred. To be compatible with
i such filling, sealing and packaqing systems, seal integrity
testing systems should run at similar high speeds.
The seal area of containers of low acid foods having
~¦ a heat-sealed lid are presently being individually visually
100% inspected rather than automatically tested by machine,
due to the difficulty of such testing at the requisite high
¦ speeds of production. Several leak detection systems have
¦ been in development to solve the problem of high speed
automatic testing of package seal integrity in a
non-destructive way. Electronic, thermal and pressure
differential systems have been proposed. However, for one
reason or another there are problems with each Oc these
systems and none is totally successful in addressing all the
needs of a fullv commercial testing system. The system should
be fast and must be sensitive, non-destructive, automatic,
reliable and accurate.
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Objectives and Features of the Invention
It is an objective of the present invention to
l provide a system and method of testing the previously dis- I
,j cussed containers, particularly the seal of lids to container
bodies in which the seal integrity of every filled container
is tested at least once, ideally twice, i.e., 200% testing.
It is a further objective of the present invention
that the seal testing be accomplished at a sufficiently high
speed so that such testing is fully compatible with the speed
of production of the filling operation. ~~
It is a further objective of the present invention
that such testing not add appreciably to the per-unit cost of
production.
It is a further objective of the present invention
that such testing provide a fully accurate test oF each seal
and ~e of sufficient accuracy to detect tiny openings through
the seal of even pin-hole size.
't is a still further objective of the present
invention to provide a container body construction which is
particularly adap ed to the testing systems and methods of the
present invention.
Tt is a stili further objective -of th.s invention to
p ovide an on-line, non-destructive system and method for
testing the seal integrity of plastic containers having sealed
or adhered covers or lids.
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It is another objective of this in~ention to provide
i' the above mentioned method and systems which are automated and
I preferably effected at high speeds compatible with high
¦ container fill and seal, line speed.
, Summary of the Invention
'l In accordance with the present invention, there are
;¦ provided methods and systems for testing the seal of container
~1 lids to the top portion preferably a top surface, e.g., lip or
! flange or both of container bodies. Each container, after it
is filled and the cover is secured or sealed to the flange, is
tested once, optionally twice, i.e., 200~ testing. If any
holes are found which extend through the seal, in either of
! the tests the container is rejected.
The container body can be made of any suitable
material(s) and can be of any suitable design, shape or
configuration and has an upper terminal end portion usually
defining the mouth of the container, preferably having an out-
wardly extending flange which extends from its top lip. The
te-minal end portion may be of any suitable shape, for
example, cylindrical, rectangular or oval. A portion of the
term nal end portion of the container body preferably a top
flattened surface of the lip or flange, is secured to the lid.
The lid or cover can be of any suitable materials or
I cons~ruction and preferably comprises a plastic-containing
¦ laminar or flexible sheet. An example of such a multi-layer
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lid would comprise, a bottom layer of plastic polymeric
, material for heat-sealing, a core layer of a metal foil and a
top layer of plastic polymeric material which preferably may
be printed upon. The upper terminal end portion of the
I container body has means adapted for the testing of the
j present invention. In preferred embodiments, the lip or
¦ flange, preferably the latter, has means for introducing a
¦~ testing medium to or into the seal between the lid and the
j surface of the terminal end portion of the container body,
¦i e.g., a peripheral channel which communicates with the I ¦
! lidJseal area of the container body, and means for introducing
,¦ a testing medium into the peripheral channel. The introducing
, means can be at least one, preferably two passageways, routes
j or openings extending from and through an outer portion, edge
or surface of the terminal e~d portion, for example, from and
¦ through the outer side wall of the flange and leading to and
¦ communicating with the channel. In one embodiment each
1 opening is a radially aligned bore, i.e., a round hole, and in
¦ another embodiment each opening is a radial groove.
, The peripheral channel in the lip or flange forms a
! passagewa~ which extends about the inner annular portion Oc
the lid-flanse seal. A suitable fluid is pumped, at high
pressure, through the routels) or opening(s) into the channel.
_f there is a leak in the seal, the fluid will pass through
the leak and into the container, expanding (bulging) the cover
upwards. That expansion is detected by suitable means such as
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j a linear transducer and the containers whose covers flex or
¦ bulge upwards under the fluid pressure of the test are by
suitable means identified and rejected.
The system includes a high-speed automatic machine
! which, in sequence, vertically moves a clamping ring to clamp,
for example, the outer portion of the rim or flange of a
I¦ sealed container, injects gas through the opening, and then
,¦ lifts the clamp-ng fixture. The faultily sealed container(s)
¦l is or are then rejected from the line. I
jl The above and other objec~ives of the present
!¦ invention will be apparent from the detailed description
,¦ provided below, which should be taken in conjunction with the
jl accompanying drawings.
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Brief DescriDtion of the Drawings
Figure 1 is a top plan view of a container body
without a lid, showing the preferred first embodiment of the
; present invention;
Fi~ure 2 is a side cross-sectional view taken along
line A-A of Figure l;
Figure 3 is a greatly enlarged top sec'ional plan
view of a portion of the container body flange shown within
the dash-dot circle of Figure l;
Figure 4A is a cross-sectional view ta~en along line
B-B of Figure 3;
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¦ Figure 4B is a cross-sectional view similar to
¦ Figure 4A but with the lid sealed in place;
! Figure 4C is a cross-sectional view taken along line
C-C of Figure 3- !
~¦ Figure S is a side plan view of a portion of a
!! flange showing a second embodiment of the present invention;
¦¦ Figure 6 is a top plan view, similar to Figure 3,
il but of the second embodiment of the present invention shown in
¦¦ Figure S;
i Figure 7 is a vertical sectional view of à port~on _.
of a flange taken along line D-D of Fig. 3 showing the first
embodiment of the invention;
. Figure 8A is a vertical cross-sectional view of a
il portion of an apparatus for testing the seal integrity of a
~! plastic container in accordance with the present invention;
¦ Figure 8~ is an enlarged view of a portion of the
apparatus of Figure 8A with a container in the apparatus;
I Figure 9 is a vertical cross-sectional view of a
! second alternative appa-atus for testing the seal integrity of.
a plastic container in accordance with the present invention,
with a cross-sectional view of a portion of a container taken
along line E-E of Figure 10;
Figure 9A is an enlarged vertical cross-sectional
view of the embodiment of Fig. 10 taken along line F~F of Fig.
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igure 9~ is an enlarged vertical cross-sectional
view of an altered embodiment of Figure 9A;
Figure 10 is a top plan view, enlarged, of an
~l optional flange structure of the flange shown in Fig. 9;
Figure 11 is a side cross-sectional view of a third
alternative apparatus for testing of the seal integrity of a
container and of another embodiment of the container
structure;
Il Figure 12 is a side plan view of a portion of the
il container shown in a cross-sectional view in Figure 11; ~
ll Figure 13 is a bottom view of a portion of the
!i apparatus shown in Figure 11; and
! Figure 14 is a vertical cross-sectional view of a
! fourth alternative apparatus for the testing of the seal
j integrity of a container.
Figure 15 is another embodiment like Figure 9A where
the lid is sealed to the inside surface of the container side
wall.
Brief Description of the Preferred Embodiments
As shown in Figures 1-4B, the preferred container of
; the present in~ention includes a flexible lid 10 (Figure 4B)
and a container body 11 here shown in the form of a bowl or
tub. The container body 11 is preferably formed of one or
more suitable plastic resin(s) and has a frustoconical or
downwardly and inwardly tapered side wall 12 (round in
horizontal cross-sectlon) and an integral bottom wall 13.
Alternatively, and not shown, the side wall may be of any
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suitable shape, for example, squared, rectangular, cylindri-
~l cal, rounded, barrel-like, etc. in cross section. The upper
terminal end portion of the container body has an integral top
~! edge, here shown as comprised of an annular flange or lip 15,
which extends radially outward from the top opening 16 of the
container body 11.
The flange 15 has a flat top face 17 and includes
!l means for introducing a testing medium into or against the
! seal between the lower face of the lid and top face 17, the
,' means being shown as a peripheral or annular channel 18 which~
¦ can but need not be, a groove or score line, which divides
face 17 into an inner annular portion 1~ and an outer annular
portion 20. The bottom face of lid 10 is secured preferably
sealed or adhered, at least to the inner annular portion l9.
Regardless of whether the seal also extends about the outer
annular portion 20, only the seal integrity of the seal about
the inner portion 19 is tested.
The outer portion 20 of the flange 15 includes means
for introducing a testing medium into channel 18. Such means
can be a single route or opening but, as here shown, pref-
erably it includes two routes or openings 23A, 23B which
extend radlally inward from and through the outer side face or
edge 22 of the flange and communicate with channel 18.
Openings 23A, 23B need not be positioned as shown, i.e., 180
apart on opposite sides of the flange. They mav be placed in
any suitable location or arrangement. The openings 23A, 23B
can be of any suitable type, shape, configuration or
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direction. Preferably they are grooves, slits, cuts or
'! channels formed or cut in the flange and preferably they are
il radial and perpendicular to the imaginary central axis 41 of
¦ the container body.
In the embodiment of Fi.gures 5 and 6, bores 25A, 25B
! (only 25B is shown) are employed as the openings instead of
the grooves 23A, 23B. The grooves 23A, 23B are easier to form
'l in the container body, but should be narrow enough to prevent
.j passage of the testing gas between the lid and the clamping
ring into the testing chamber, especially when the lidstock is - i
thin. The test gas TG introduced through the openings is
distributed by channel 18 around and tests the entire
periphery of the seal 21 at or between the bottom face of the
lid 10 and the flange inner annular portion 19, (See Figure
4B)-
In both e~bodiments, when gas TG is injected intothe channel 18 through the openings, the gas will travel
through and completely around channel 18 and the seal 21. If
there is any hole, void or interruption throush seal 21, even .
a pin-prick size hole or a weakness in the seal which will not
withstand the gas pressure, the gas will enter the container
and expand, bulge or move the cover upwardly. Such bulging,
expansion or movement of lid 10 will be sensed by suitable
means, for example, by a linear proximity transducer 26. The
defective con'ainer is identified or no4ed by suitable means.
Me~ns, for exampie and preferably, a computer-based digital
memory will, in effect, note and remember the position of the
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identified defective container in the production line and
reject it from or after it exits from the testing station.
The testing apparatus, shown in Figure 8A, is a
machine to automatically, and at high speed, provide a 100~ i
seal integrity test. The embodiment of Figure 8A is only
,1 illustrative of one possible tlesting machine design. Since
¦¦ the testing station should be integrated into or used in or
! with different types of production lines for different con-
, tainers and products, it may be constructed using various
!i mechanisms. In all cases, however, it will be adapted to --~
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!i provide a 100~ test and preferably utilized twice or at two
¦ locations for a ~00~ test, by injecting gas, under pressure,
through the two openings. If only one opening is used, and
that opening is blocked, or there is a blockage in the channel
,¦ at the junction of the channel and the opening, the test may
appear satisfactory, i.e., a false positive reading because
the cover does not bulge, and yet there may be a laak throuyh
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the seal 21. That type of false positive is avoided b~y
introducing the gas, simultaneously, through two or more
widely separated openings. The gas enters the channel through
the two openings each time the seal in egrity is tested. The
openings also permit air to ente. and diffuse through the
channel acter the container is packed. This tends to help
keep the channel dry.
As shown in Figures 8A and 8B, the container, after
being filled and having the lid 10 heat-sealed or otherwise
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secured or adhered to the flange 15, is automatically posi- j
tioned in a suitable testing apparatus by a conventional
, transfer mechanism (not shown). In the apparatus, the bottom
! face 29 of the flange 15 rests on the fixed support ledge 30.
~ A vertically movable annular clamping ring 31 is then brought
I down to clamp flange outer annular portion 20, and partially
,, but not completely over clamp channel 18, between the clamping
! ring 31 and ledge 30~ The use of O-rings 43 and 44 provides a
i gas tight seal and forms an annular gas chamber 32. The gas
! inlet 33 is connected through a solenoid-operated valve~to a~
! high pressure gas supply (not shown). After the container 11
I is clamped in position but before the pressure chamber 32 is
pressurised, the proximity transducer 26 is read. At a
parametric time during or after pressurization of chamber 32,
!! the transducer 26 is read again. If a difference greater than
!l a predetermined amount is sensed then this container will be
earmarked for automatic reject-on by simple means (not shown)
after pressure release and the lifti~g of clamping ring 31.
In the embodiments of Figures 1-8, a circumferen.ial
channel 18 with openings 23A, 23B or 25A, 25B leading to
circumferential channel 18 is employed in the flange 15 of
container 11. ~he circumferer.tial channel 18 may collect food
due ~o splashing or otherwise during the filling operation, or
collect dirt during processing or storage. This is unsightly
'¦ and unhygenic. One possible and preferred solution is in a
,~ secondary operation, after testing, to cut of f flange portion
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il 20 with or without, preferably with all of the residual
portion of the channel, that is the portion of the flange
which forms the bottom of channel 18. To avoid this extra
operation, an embodiment which dispenses with the
circumferential channel 18 is desirable and preferred. One
such embodiment is shown in Figures 9-10 in which the radial
i slots 23C penetrate further in towards the container axis 41
and further than the inner edge of clamping 31. In Figure 9,
¦ a vertical section is shown taken along F-E Figure 10 of such
i a container embodiment here shown in a testing apparatus~ ~
!I Test gas conveyed inwards by c~annel 23C moves around the
il circumference of the container in the natural channel provided
by unsealed area of lid 10 between portions 19' and 20', of
Fig. 10.
The embodiment, illustrated in Figures 11, 12 and 13
does not use a peripheral channel or one or more individual
grooves. In this embodiment, the flange 15" has a raised
inner annular portion 19~ and a depressed or offset outer
annular portion ~0". This ou~er portion can merely be a
slopinq outer portion or edge as shown in Figure 11. The
testing apparatus, par'lv shown in Figure ll, operates in the
same manner as the apparatus of Figure 8A. The container is
t-ansferred into the apparatus with its flange 15" positioned
on fixed ledge 30". The lid 10', about its outer edge,
preferably is held by vacuum up against the clamping ring 31'
; when the clamping ring 31' is lowered. The vacuum is applied,
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,j for example, through holes 46 ln clamping ring 31'. The
¦ testing gas TG, shown by arrow TG, from chamber 32" enters the
gap 47 between the bottom face of the outer edge portion of
1 lid 10' and outer depressed annular portion 20". The gas
¦ tests the peripheral seal holding cover 10' to the inner
¦ annular portion l9n. As previously mentioned, preferably the
¦ seal is tested again at another location. After the seal
! integrity tests are completed, the container preferably is
i transferred to another station (not shown) where the bottom
il face of cover lO' at its outer edge may be secured or sealed
¦1 to, for example, the outer annular portion of the flange, here
j shown as 20 n,
¦ The embodiment illustrated in Figure 14 uses a
¦¦ conventional container having container body 11 n t flange
I portion lS" and lid 10" whose bottom face, at its outer
i! peripheral edge, is sealed to the top flat face of flange lSn.
The flange 15" does not have a channel, groove or hole. The
integritv of the seal is tested by gas TG when the clamping
ring ~l" is lowered near to or onto the lid 10" and a vacuum
~i is applied to hole 46". An outer chamber 32" is temporarily
I formed by the clampins -ing 31". When the gas from ou'er
chamber i2"space is pressurized, ring 31" is li'ted slightly.
~ If there is a hole in the seal, gas will enter the container
!, and cause the lid 10" to bulge outward, activating a
transducer (not shown). The clamping ring, of the type shown
in Figure 13, uses vacuum V. After the seal integrity is
tested the vacuum is shut off, the
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rin~ 31" is lifted frorn the lid lO~ and the container is
I¦ removed from the testing apparatus.
,l¦ Modifications may be made in the above-described
¦¦ embodiments within the scope oi- the claims. For example, the
container body shown in the drawings is bowl-shaped. However,
I¦ alternatively, the container body may have arcuate or rounded
¦¦ portions or straight or flat sides and be triangular,
rectangular, or have more than four side walls, As additional
: examples, the container body may be a right-sided cylinder, or ' .
cone shaped. It may be formed from one layer or -- --
~j multiple-layers of plastic or plastic and foil. It could also
!I be a suitable composite material.
The flange 15 is shown, in the drawings, as a flat
1 annular member, having a channel therein, which extends
'! horizontally outwardly from the top of the container body,
perpendicular to the imaginary axis of the container body.
i Alternatively, and not shown, the flange may extend outwardly
at an incline or obtuse angle to the axis, or the flange may
be parallel or downwardly angled relative to the axis, for
example, an upward or downward extension o~ the side wall of
the container body. The flange may also extend inwa-d, i.e.,
toward the axis.
The embodiments, described above, show the flange 15
; as an integral portion of the container body. Alternatively,
and not shown, the flange may be a separate ring which is
welded or otherwise connected to the body.
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The container body terminal end portion need not
Il include a flange. Instead, the channel 18 may be formed in
¦l the upper edge or lip of the container. For that purpose, the
¦¦ lip may be thickened compared to the container body's side
¦l wall.
he lid or cover 10 is described, in one embodiment,
11 as a multi-layer flexible sheet. The cover may be of a single
¦~ layer. It may be semi-rigid and need not be formed using a
!l plastic film or laminate. It may be injection molded. The
j cover, however, must be able to flex, bend, bulge or expand
1 due to the pressure o~ th~ testing gas to an extent as to be
¦! detectable by the testing apparatus employed and properly
1 attributable to a seal leak.
i The channel 18 and the grooves are shown as being
! U-shaped with square bottom corners. Alternatively, and not
jl shown, the channel and grooves may have other cross-sectional
¦ shapes including rectangular, square, hemi-spherical and
V-shaped. One peripheral channel is shown, however two or
more channels, each communicating through grooves or bores to
the side wall, may be utili~ed. There may be many grooves,
openings or bores in the flange outer annular portion.
In the above-described embodiments, the cover is
heat-sealed or otherwise adhered to the flange. Other sealing
methods may be used, for example, a plastic cover may be spin
` welded to a container body, or the seal may be 'ormed ultra-
-~ sonically. The adhesive, for example, may be a heat set or a
i ~old_se~.~
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The gas used in the test is preferably air, pref-
~~ erably ho~ air, to help dry the channel, or it may be an inert
¦¦ gas such as nitrogen, helium or argon.
Figure 15 is a ~ertical section through an alternate
,¦ embodiment of the container of this invention whose lid is
`' sealed to the inside surface oE the container side wall. More
Il particularly, Figure 15 shows a container 61 having a side
,¦ wall 6 , an outwardly flared or stepped marginal end portion
i! 64 having a passageway opening 63 therethrough. The container
l! is sealed by a lid 66-recessed into the container body and
Il sealed about its peripheral marginal edge portion at 68 (lower
!i seal) and 69 (upper seal). The upper seal is optional. In
! this embodiment the testing fluid is injected through opening
63 and tests seal 68.
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