Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND APPARATUS FOR MAKING A PRE-PADDED
FOOD BAG
BACKGROUND OF THE IIwTVENTION
Field of the Invention
The present invention relates to a method and apparatus for making a pre-
padded food-containing bag for such products as fresh poultry and meat. More
particularly, this invention relates to methods and apparatus for placing an
absorbent pad into a food-containing bag made from a web of tubular
thermoplastic material.
Description of the Prior Art.
Poultry and meat are frequently sold in transparent plastic bags. Despite
the customer being able to see the contents of the bag prior to purchasing, a
problem with this type of packaging is that the poultry or meat, no matter how
carefully prepared, contains residual blood and other fluids that flow out of
the
meat after it has been packaged. The blood and other fluids accumulate in the
package, thereby detracting from its appearance. In addition, the blood and
fluid
sometimes leak from the package while the consumer is transporting it home
from
the market. To counter this problem food bag manufacturers include an
absorbent
pad in the bag prior to loading the food product. The pad absorbs the exuded
blood
and fluid into the pad and also enhances the appearance of the finished bagged
product. The manual labor associated with placing the absorbent pad in the bag
prior to product loading adds to the cost and time associated with this
operation.
There are numerous patents directed to thermoplastic food bags with an
absorbent pad for packaging food products. One such patent is U. S. Patent No.
4,815,590 to Peppiatt, et al. that discloses a generally rectangular pad
attached to
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the side closest to the bag opening so that the pad is not dislodged when the
product is placed in the bag. The pad absorbs blood and other fluids in the
meats
to keep the package neat and clean and minimize th.e danger of leakage.
An example of a pad for absorbing exuded juices or liquids is shown in U.
S. Patent No. 4,410,578 to Miller. This patent discloses an absorbent pad for
use
in a bag or tray intended to contain and display fresh food such as poultry or
meat.
The absorbent pad includes a mat of liquid absorbing material, and liquid
impermeable plastic sheets overlying and underlying the absorbent mat. At
least
one of the sheets is perforated, and a spacer is disposed between the two
liquid
impermeable plastic sheets to maintain their separation under the compressive
load
of the food product resting thereon, such that the ability of the pad to
absorb
liquids is unimpaired. When a food product is positioned upon the upper sheet
of
the absorbent pad, any exuded liquids will flow around the pad and enter the
pad
by capillary action through the perforated openings in the bottom sheet, and
the
liquids will be held out of contact with the food product minimizing
contamination
of the product, maintaining its appearance, and improving its shelf life.
There remains a need for a pre-padded thermoplastic food bag. Such a bag
would increase packaging rates and reduce labor cost at the packing plant.
BRIEF SUMMARY OF THE I7~1VENTION
It is an object of the present invention to provide a method for making a
food-containing bag from a web of thermoplastic tubular material and placing
an
absorbent pad therein.
Another object of the present invention is to provide an apparatus for
making a food-containing bag having an absorbent pad therein from a web of
thermoplastic tubular material.
Yet another object of the present invention is the provision of a method for
manufacturing pre-padded food-containing bags that have fewer seals than
conventional bags.
A further object of the present invention is to provide a pre-padded food-
containing bag available in roll form.
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It has been found that the foregoing objects may be accomplished in
accordance with this invention by providing a method for manufacturing pre-
padded food-containing bag by perforating across a continuous web of flattened
tubular thermoplastic material, forming an opening in a layer of the
perforated
web, separating the layers of the web, placing an absorbent pad through the
opening into the inside of the tubular web and making a seal across the
tubular web
at predetermined lengths to form a bag. The result :is a continuous web of
bags
containing absorbent pads at discrete intervals. There is also provided an
apparatus
for carrying out the method.
More specifically, in a preferred embodiment, a predetermined continuous
length of lay-flat seamless tubular thermoplastic web is unwound from a roll.
The
layers of the lay-flat tubular web are perforated at a predetermined length.
The
tubular web is fed through a tube opener where the upper layer perforations
are
separated creating an opening. The tubular web then passes to the inserter
where
during the seal dwell time, a pair of nip rollers, located at a predetermined
distance
from the web opening, squeeze the upper and bottom layers together. Air is
blown
into the opening in an amount sufficient to cause the upper layer of the
tubular web
to open sufficiently wide for an absorbent pad to be inserted through the
opening.
The absorbent pad may have either pressure sensitive or low temperature food
grade adhesive attached on one side thereof so that when the excess air is
removed
from the tubular web the pad is adhered to one of the layers. The tubular web,
having the absorbent pad positioned between the layers, passes between
laterally
adjustable nip rollers to squeeze the air out of the tubing prior to entering
the
sealer. As the tubular web passes through the sealer a transverse seal is
made. The
sealer is displaced transversely across the tubular we°b for delimiting
a
predetermined length serving to define the bag size. The seal may be straight
or
curved. The seal can be made using an impulse sealer which employs a hot wire.
The bags containing the pads may be wound into a roll and separated when used
at
the perforations in the bottom layer of the tubular web. There is also
provided an
apparatus for carrying out the method.
In a second embodiment, the method is similar to the first embodiment
described above but differs in that when the tubular web passes through the
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perforator and opener the bottom layer of the tubular web is perforated and
the
upper layer is severed or cut. A knife is provided on reciprocating base to
cut a slit
through the upper layer but not the bottom layer. The perforations in the
bottom
layer are provided by perforation knife positioned in restraining block and
piercing
only the bottom layer. To insert the pad it is necessary to open the layers of
the
tubular web from each other so that air may be blown into the tube to make the
tube wide enough to insert the pad. There are several means for separating the
layers from each other, such as the eccentric wheel of the first embodiment or
vacuum cups. The pad is inserted and the bag is form by sealing as in the
first
embodiment.
In another embodiment, the flat tubular web is slit along one side and the
absorbent pad is inserted at a right angle to the direction of travel of the
web and
the slit side is heat sealed.
The packaging costs at the consumer level are reduced due to reduction in
labor costs associated with manual placement of pads in bag and subsequent
increase in productivity by the use of the pre-padded bags. In addition, there
are
other applications where it is desirable to scavenge oxygen from the bagged
product, or add moisture in the bar or anti-microbial pad in the bagged
product.
All the above can be accomplished by having a pre-padded bag with the
appropriate pad.
Other objects, features and advantages of the invention will become evident
from the following description of the drawings and detailed description of the
invention.
BRIEF DESCRIPTIOI~T OF THE DRAWINGS
Having thus described the invention in general terms, reference will now be
made to the accompanying drawings, which are not necessarily drawn to scale,
and
wherein:
FIG. 1 is a front view of a bag-forming machine used to make pre-padded
bags according to an embodiment of the present invention;
FIG. 2 is an isometric view of an absorbent pad positioned in a transparent
thermoplastic bag made according to the method of this invention;
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FIG. 3A-3E show a scheanatic of the method of forming bags with
adsorbent pads of one of the preferred embodiments of the present invention;
FIG. 4 is a top view showing the path of the tubular web shown in the
method of FIGS. 3A-3E;
FIG. 5 is a top view of the pad inserting section of the method of the
present invention showing inline insertion of the pads;
FIG. 6 is a side view of the pad inserting section of the bag-forming
machine;
FIG. 7 illustrates another embodiment of the pad inserting section of the
present invention showing insertion of absorbent pads at a right angle to the
direction of travel of the web;
FIG. 8 shows a side view of an alternative embodiment of the pad inserter
taken along line 8-8 of FIG. 7;
FIG. 9A-9E shows the steps used in the method shown in FIGS. 7-8;
FIG. 10 illustrates an alternative transverse seal - a curved seal; and
FIG. 11 illustrates the pad having an adhesive attached thereto.
DETAILED DESCRIPTION OF THE INVENTION
The present inventions now will be described more fully hereinafter with
reference to the accompanying drawings, in which some, but not all embodiments
of the invention are shown. Indeed, these inventions may be embodied in many
different forms and should not be construed as limited to the embodiments set
forth
herein; rather, these embodiments are provided so that this disclosure will
satisfy
applicable legal requirements. Like numbers refer to like elements throughout.
Referring now to drawings, there is show in FIG. 1 a bag forming machine
for making a pre-padded food-containing bag such as the one shown in FIG. 2.
The bag 10 is made from conventional tubular thermoplastic packaging material
that is defined by seals 30 and has a fluid-absorbing pad 25 placed therein.
Typically, the thermoplastic material will be polyethylene, although other
thermoplastic materials known to those skilled in the art may be used, such as
the
materials disclosed in U. S. Patent No. 3,741,253 to Brax.
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As shown in FIG. 1, the bag-forming machine 100 includes a tubular web
supply section 120 and a bag forming section 130. The tubular web supply
section
120 includes a pair of cradles 123 mounted on a support base 121 and spaced
apart
from each other a sufficient distance to accommodate a roll 12 of tubular
plastic
material. The continuous length of lay-flat seamless tubular web 11 may be
unwound from the roll 12 and passed around guide roll 124.
The tubular thermoplastic web 11 is drawn i:n a flattened condition from the
supply section 120 to the bag forming section 130 through the nips of
tensioning
rolls 125, 126 and 127, 128 and around guide roll 129. A pair of drive rolls
131,
132 forming a nip through which the tubular web 11 passes is provided. The
tubular web 11 passes around idler roll 133 and is guided by guide rollers
134, 135,
136, 137 to the tube perforator and opener 140.
The tubular web passes through the perforator and opener 140 where the
bottom layer of the tubular web is perforated and the upper layer is severed
or cut
at a predetermined length. A knife 141 is provided on reciprocating base 142
to
cut the upper layer. The perforations in the bottom layer are provided by
perforation knife (not shown) positioned in restraining block 143 and piercing
only
the bottom layer. To insert the pad it is necessary to open the layers of the
tubular
web 11 from each other so that air may be blown into the tube to make the tube
wide enough to insert the pad. There are several means for separating the
layers
from each other to create a bag opening, such as an eccentric wheel (FIG. 3)
or
vacuum cups (not shown).
The tubular web 11 then lead to the pad insertion section 150 by passing
the tubular web 11 around guide roll 155. During the seal dwell time, pair of
laterally adjustable nip rollers 151, 152 positioned prior to the sealer 160
and
located at a predetermined distance from the opening in tubular web 11 to
squeeze
the upper and bottom layers together squeezing the air out of the tubular web.
The
nip rollers are positioned from the opening 20 at a predetermined distance to
correspond with the length between the perforations 17 (FIG. 4). The length of
the
bag 10 may be varied by changing the distance between the perforations 17 and
changing the distance from the opening 20 at the pad inserter to the nip
rollers.
Blower 153 blows air into the opening formed in the tubular web causing it to
open
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wide enough to insert an absorbent pad. At the same time a pad 25 passes from
pad inserter 154 through the opening in the tubular web where the pad comes to
rest inside the tubular web 11. The pad inserter is r~nounted to vertically
adjustable
support 157.
Sealer 160 is displaced transversely across the tubular web 11 for forming
bag 10 at a predetermined a length. The sealer 160 may include a sealing bar
161
which when in sealing position is disposed against restraining bar 162
opposite
each other forms a transverse seal (straight or curved heat seal) to form the
bag. A
hydraulic cylinder 163 is provided for advancing and retracting the seal bar
161
and restraining bar 162 toward and away from the tubular web 11. It will be
understood by those skilled in the art that means other than a hydraulic
cylinder,
e.g. electric motor, may be used to advance and retract the seal bar. The
continuous length of perforated, pre-padded bags then passes to winder
assembly
170 where the bags are wound up in a roll 31. When roll 31 is full the
continuous
length of pre-padded bags is shifted to a second roll. 31' and roll 31 is
removed and
set up for another winding operation when roll 31' is full.
A method far making the pre-padded bags 10 is shown in FIGS 3A-3E
wherein a roll 31 of individual bags 10 each having an absorbent pad 25 is
produced. In FIG. 3A, at station #l, a predetermined continuous length of lay-
flat
seamless tubular thermoplastic web 11 is unwound from roll 12. The lay-flat
tubular web 11 has an upper layer 13 and the bottom layer 14. The tubular web
11
is fed along a path of travel to a perforator 15 and backing bar 16 where the
upper
layer 13 and the bottom layer 14 of tubular web 11 are perforated at a
predetermined length to define the length of the bag (FIG. 4). The
perforations are
shown by forming line I7 in FIG. 4. In the case of the upper layer 13 the
perforation is used to form opening 20 and in the case of the bottom layer 14
the
perforation is used to separate each bag for the next succeeding bag.
The perforated tubular web 11 is fed to station #2 shown in FIG. 3B,
through a tube opener where the upper layer 13 perforations are separated
creating
an opening 20. In the embodiment shown in FIG. 3B the opening is provided
using eccentric wheel 1S acting against the upper layer 13 of the tubular web
and a
back up roller 19 to separate at the perforation in upper layer 13. In another
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embodiment, that shown in FIG. 1, the opening is formed by severing or cutting
upper layer 13 and perforating the bottom layer 14.
As shown in FIG 3C, the tubular web 11 next passes to station #3 for pad
insertion from the pad inserter 24 where during the seal dwell time pair of
nip
rollers 21, 22 located at a predetermined distance from the opening 20 to
squeeze
the upper layer 13 and bottom layer 14 together to close off a section of the
tubular
web 11 ahead of the absorbent pad 25 so that when the air from air source 23
is
blown into the opening 20 the upper layer 13 and the bottom layer 14 of the
tubular
web 11 are caused to separate sufficiently for absorbent pad 25 to be placed
through the opening and into the tubular web. At the same time the absorbent
pad
25 is inserted inside the tubular web 11 through the opening 20.
As shown in the enlarged views of FIGs. 5 a.nd 6 the pad 25 is dispensed
from a roll of pads 24, such as DRI-LOC~ absorbent pads available from Sealed
Air Corporation, and inserted inline in the direction of travel of the tubular
web. In
FIGS S and 6 only bottom layer 14 of the tubular web is shown for clarity.
Thus,
because upper layer 13 is not shown, opening 20 is not shown. In the
embodiment
shawn in FIG. 5 an indefinite length of pads is fed intermittently at a
predetermined time interval from a stock roll 24 a cutting device (not shown)
severs the pads from each other. Each pad is then delivered at the
predetermined
time into the opening 20 of the tubular web. The blowing air assists in
pushing the
pad into the tubular web. As shown in FIG. 11, The absorbent pad may have
either
pressure sensitive or low temperature food grade adhesive on one side thereof
so
that when the excess air is removed from the tubular web 11 the pad is adhered
to
one of the layers, preferably the bottom layer 14.
The excess air is removed from the tubular web 11 having the absorbent
pad 25 positioned between the upper layer 13 and th:e bottom layer 14. As
shown
in FIG. 3D, station #4, one method of removing the excess air is to pass the
tubular
web 11 between laterally adjustable nip rollers 26, 27 to squeeze the excess
air
from the tubing prior to forming the bag.
Bags are then formed at station #5 by converting the tubular web 11 into a
continuous series of connected end-seal bags 10, each containing an absorbent
pad
as shown in FIG. 3E. The bags may be formed by sealing the tubular web across
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its width at discrete intervals. As the tubular web 11 passes between sealer
28 and
restraining bar 29 a transverse seal 30 is made by heated sealing member 28.
The
sealing member 28 is displaced transversely across the tubular web 11 for
delimiting a predetermined length serving to limit the size bag 10. The
sealing
member 28 is moved toward the restraining bar 29 to form a seal 30. The seal
30
may be straight, as shown in FIG. 2 or curved as shown in FIG. 10. It should
be
understood that any well-known method of sealing is used to form the bags 10.
The bags containing the pads may be wound into a .roll 31. Alternatively, the
bags
may be folded along the seal and placed in a box until used.
FIGs. 7 and 8 illustrate an embodiment of the absorbent pad dispensing
portion of the apparatus showing delivery from a roll 24 of absorbent pads 25
at an
angle, preferably a right angle, to the direction of travel of the bottom
layer 14 of
tubular web 11 intermittent of perforations 17. Far purposes of illustration,
the
upper layer 13 is not shown. In the embodiment of FIG. 7, the flat tubular web
11
(see FIG. 9A) is slit along one side of the flattened tubular web 11 at slit
line 32
(FIG. 9B). The absorbent pad 25 is inserted through the slit line 32 at an
angle to
the direction of travel of the web 11 as shown in FI(s. 9C. The split side of
the
tubular web 11 containing the pad 25 is band sealed 33 as shown in FIG. 9D.
Transverse straight seal 30 (FIG. 9E) or curved seal 30 FIG. 10) may be used
to
complete the pre-padded bag 10.
Many modifications and other embodiments of the inventions set forth
herein will come to mind to one skilled in the art to which these inventions
pertain
having the benefit of the teachings presented in the foregoing descriptions
and the
associated drawings. Therefore, it is to be understood that the inventions are
not to
be limited to the specific embodiments disclosed and that modifications and
other
embodiments are intended to be included within the scope of the appended
claims.
Although specific terms are employed herein, they are used in a generic and
descriptive sense only and not for purposes of limitation.
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