Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~427~
FIELD OF THE INVENTIO~
The present invention relates to a method of handling a
pre-formed filled bag where the mouth of the bag is sealed
and a separate closure is applied to the bag.
,
.
.
2~27~
BACKGRO~ND OF THE INVENTION
Product tampering in retail outlets at the point of sale
has become a very big problem. Tamper-proof caps are
provided on pill bot~les and the like. There is, however,
nothing in the way of tamper-prevention seals provided on
currently available pre-formed open-mouthed bags, such as
bakery products, produce, ice, citrus, fruit and milk bags.
In contrast, these particular types of bags are simply
secured by a reusable closure which can easily be removed
from the bag, allowing tampering and replacement of the
closures. Accordingly, a person buying bagged milk and/or
a bag of bread would not have any means of determining
whether or not there had been any tampering to the product
in the bag.
Certain types of bags are sealed. These are referred to as
form-filled bags such as those used for packaging of
candies. ~ form-filled bag is one in which an elongated
tube of bag material is cut at specific locations to make
smaller bags which are filled with material and sealed.
The sealing is achieved while the bag is in a relatively
stationary position.
Form-filled bags are to be distinguished from pre-formed
bags. A pre-formed bag is one which is made with a closed
bottom and an open mouth for receiving product to be later
deposited into the bag. Pre-formed bags such as the milk
and bread bags noted above, are fed along a moving conveyor
for closure of the bag. These types of bags have not been
successfully sealed because any consideration with respect
to sealing has been dismissed in view of the fact that
these bags are continuously moving along a bag handling
system. Therefore, it has considered in the past that the
seal would not have time to set and therefore the stress
caused by the product in the bag would cause the seal to
separate. Furthermore the seal cannot be applied
sufficiently close to the product to prevent its shifting
in the bag.
,
,
-
,
2~42~D
SUMMARY OF THE PRESENT INVENTION
The present invention provides a method of handling a pre-
formed open-mouth bag having a filled and an unfilled bag
portion. The method is carried out while continuously
conveying the bag through a plurality of bag handling
stations and comprises gripping the unfilled bag portion
which produces a flattening of the unfilled bag portion
with the mouth of the bag in an essentially unstressed
condition, sealing the mouth of the bag and applying a
reusable bag closure to the unfilled portion of the bag.
The key to the present invention is the gripping of the
unfilled bag portion away from the bag mouth in a manner
such that there is no stress on the seal as it is applied
to the bag mouth. This particular feature allows the
sealing process to be carried out while the bag is in
continuous movement through the bag handling system because
the seal does not have to set against pressure created by
product within the bag. It is the bag grippers rather than
the seal that absorbs the pressure of the product in the
bag.
:
'";~
21D~270
BRIEF DESCRIPTION OF THE DRAWINGS
The above as well as other advantages and features of the
present invention will be described in greater detail
according to the preferred embodiments of the present
invention in which Figure 1 is a perspective view of a bag
handling system according to a preferred embodiment of the
present invention. Figure 2 is an end view of the bag
sealing station from the system of Figure 1. Figure 2A iS
a perspective view of the belts used in the bag handling
station of Figure 2. Figure 2B iS an enlarged perspective
view of the heat sealer of Figure 2. Figure 2C is a side
view of the upper end of the bag after having gone through
the heat sealing station of Figure 2. Figure 3 is a
perspective view of an alternate bag handling system
according to a further preferred embodiment of the present
invention.
.
.~ . . .
- ~ .
~ .
DETAILED DESCRIPTION ACCORDI~G TO THE PREFERRED EMBODIME~ 2
O~F TH~ PRESENT INVENTION
Figure 1 shows an overall bag handling system generally
indicated at 1. This bag handling system is used to handle
a pre-~ormed open-mouth bag generally indicated at 3. sag
3 as best seen to the left hand side of the drawing has an
open mouth 5 and a sealed bottom 6. This bag is previously
filled with product P. In this particular case the product
is three sealed milk pouc~les.
As best indicated in Step 2 of Figure 1, the bag where
loaded comprises a filled bag portion 7 and above that
there is an unfilled bag portion 9. The unfilled bag
portion terminates in the mouth 5, which is initially open
and then sealed by the end of the bag handling line.
The bag is placed as shown in the left hand side of Figure
1 with its sealed bottom on a conveyor 11. The open mouth
is located at the top of the bag. The bag is carried by
the conveyor to a pair of rotating brushes 13, where the
unfilled bag portion is fed between the brushes, which
rotate to expel air from the upper part of the bag and
which push up the unfilled bag portion. This provides in
effect a preshaping of the bag,at the juncture between the
unfilled bag portion and the filled bag portion, as
indicated at 10 in Figure 2. There is stress on the bag at
this preshaped region but the unfilled bag portion,
specifically the mouth of the bag, is slack or unstressed
above the preshaped region.
The bag passes immediately from the brushes to a further
bag handling station including a pair of rotating belts 15
which grip the unfilled bag portion beneath the open mouth
after it has been preshaped by the brushes. Both the
brushing and the gripping of the bag b~ belts 15 causes the
unfilled bag portion to flatten, with the bag mouth 5 in an
essentially unstressed condition. The belts hold the
unfilled bag portion so that it stands upright where the
21D&4270
bag mouth 5 is fed through a pair of heat sealers 17,
producing a seal 19 along the mouth of the bag. This seal
i~ applied a~ the bag continuously moves through the
gripping and sealing station without slowing the bag
handling operation whatsoever. As earlier stated, the
reason that the bag is able to continuously move and at the
same time be effectively sealed is that the bag mouth is
not under any pressure to separate while the seal is
applied so that the seal does not have to be held while it
sets.
In the particular arrangement shown the Figures 2 and 2B
the heat sealers comprise rotating heat seal wheels, one of
which is provided with unheated serrating teeth 18. These
teeth prescore the bag as indicated at 20 immediately
beneath the heat seal 19.
In addition, heat seal wheels 17 are divided into an upper
heated wheel portion 17c and a lower unheated wheel portion
17d. The upper heat wheel portion performs the heat
sealing operation~ The lower unheated wheel portion
includes an embossed bag coder which applies a bag code 22
beneath the serration as also seen in Figure 2C.
The preweakening of the bag by the serrations allows easy
removal of the seal by the consumer. However any tampering
at the bag top prior to purchases is still evident.
The bag code, which is pressed into the bag rather than
including anything in the way of printing inks etc,
indicates things such as where the product originated, date
of the product etc. The code stays with the bag even after
the seal has been removed. In the case of products such as
bagged milk this is important because the manufacturer can
easily deterine whether product returns are ~ustified. If
the retailer attempts to switch the product from one bag to
another the seal again indicates ~retailer tampering.~
'
2~270
After the bag mouth is sealed it is then passed onto a
reusable closure applying station 21. This station
presents a closure member 25, which could be wire, tape,
etc. or as shown a KWIK LOKtm, which is a small plastic
clip into which the bag is fed by a pair of rollers 23,
which are part of the closure application station. After
the closure has been applied, the bag includes both a
sealed mouth and a reusable bag closure as shown to the far
righ~ hand side of Figure 1. This is the way the bag
appears in the retail outlet. Note that the KWIK ~OK and
not the seal is tightly against the product prevents its
shifting in the bag.
Figure 3 shows a slightly different bag handling system
from that shown in Figure 1. In this particular setup the
product P1, loaded into bag 3A, is bread. In this case the
bag is shown as heing handled in a horizontal as opposed to
a vertical position. Furthermore, Figure 3 shows the
additional step of loading the bread into the bag.
Pre-formed bag 3A includes a previously sealed end 6A and
an open mouth 5A, through which the bread is loaded into
the bag. This produces a filled bag portion 7A and an
unfilled bag portion 9A. The b,ag is moved along a
continuous conveying system to a pair of brushes 13A which
expel air from the bag and preshape the unfilled bag to
collapse inwardly around the product in the filled bag
portion while flattening the unfilled bag portion outwardly
away from the product in the bag.
After leaving brushes 13A, the bag is passe~ to a bag
gripping and sealing station including gripping belts 15A
and heat sealers 17A provided with attached unheated
serrating teeth l9A. These heat sealers provide a seal l9A
along the mouth of the bag and also serrate or prescore the
bag immediately beneath seal 19A.
' . , .
. . i
After the bag mouth is sealed, it is passed to a closu~e~ ~ 2 7
applying station substantially the same as that shown in
Figure 1, resulting in a bag that includes a sealed mouth
as well as a reusable closure applied to the unfilled bag
portion between the product and the mouth of the bag.
In both of the examples shown in Figures 1 and 3, the pre-
formed bag is only filled to a depth such that it leaves a
workable unfilled bag portion referred to as a bag tail.
This bag tail must be sufficiently long to allow preshaping
of the unfilled bag portion around the product in a manner
which still leaves the bag mouth slack or unstressed for
sealing while the bag continuously moves along the bag
handling system.
At the point of sale and in contrast to presently ex~isting
bread and milk bags, the bag cannot be tampered with by
simply removing the closure, opening the bag, inserting a
foreign substance into the bag, and then reclosing the bag.
With bags manufactured according to the present invention
the seal would first have to be opened, which would
immediately indicate the possibility of some tampering
having been done to the bag contents.
After purchasing the bag and when the consumer takes the
bag home, the seal can quickly and easily be removed,
either by cutting it from the bag or, in the case of a
preweakened bag, by ripping it from the top of the bag.
However, even after the seal has been removed there is more
than enough of a bag tail to reuse the closure applied to
the bag.
Although various preferred embodiments of the invention
have been described in detail, it will appreciated by those
skilled in the arts that variations may be made without
departing from the spirit of the invention or scope of the
appended claims.
. . '
,
