Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FLAT BOTTOMED PLASTIC BAG
This invention relates to plastic flat bottom bags. More particularly, a
plastic flat
bottom bag is illustrated where either a hinge, a cold seal, and/or a hybrid
cold seal and
hinge forms a linear folding axis for squaring out the bottom of the bag. This
construction enables rapid bag manufacture of the resultant flat bottom bag
making this
design competitive for the first time with conventional plastic bags.
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BACKGROUND OF THE INVENTION
Flat bottom plastic bags are known.
In such flat bottom plastic bags, it is necessary to form a folding axis so
that upon
bag opening, the flat bottom of the bag hinges along diagonal fold lines to
"square out"
and form an upstanding bag structure for the receipt of articles to be placed
in the bag. In
addition to paper bags in commerce, exemplary of the prior art is:
Platz et al US Patent 3,917, 159 takes an already manufactured bag and folds
the
bottom so that it will "square out."
Le Fleur et al US Patent 3,915,077 utilizes individual heat seals to form the
"squared out" portion of the bag.
Hanson et al US Patent 3,988,970 discloses a bag process where a square bottom
bag is first produced. Thereafter, the bag is folded so that the plastic film
emulates the
folding present in ordinary paper bags. This folding process occurs after the
square
bottom bag is fully manufactured.
Ross et al relates to a plastic bag that utilizes among other constituents
glue.
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In the disclosure that follows, a plastic bag is manufactured which uses
either "cold seals", hinges, and/or hybrid cold seals and hinges in plastic
film for the rapid
production and formation of a plastic bag. It is important that the reader
understand both
of the "cold seal" and "hinge" terms and how they are limited in the
disclosure that
follows.
First, it is important to understand that in modem plastic bag
manufacturing technology, speed of film processing is essential. In a typical
bag
manufacturing process, fi1m passes through a machine for bag manufacture at
rates up to
300 feet per minute is required for economic manufacture. Further, each
manufacturing
step must anticipate the subsequent opening and loading of the bag. As a
consequence,
steps taldng an inordinate amount of time slow down the bag line speed and are
generally
unacceptable. Further, any bag post-production step - such as folding an
already
manufactured bag - is unacceptable.
Because of this speed requirement, so-called "hot seals" are generally not
acceptable for any portion of the bag that does not require full strength
sealing. In a hot
seal, one film layer of a bag is permanently fused to another film layer of a
bag. Hot seals
take time to produce. Melting must be sufficient for complete fusing to take
place
between the bag parts. As a result, a hot seal is a significantly slower
method of plastic
bag manufacture than either utilizing a "cold seal" or forming a "hinge"
within plastic
film.
In a hot seal application transverse to the direction of film conveyance
during plastic film bag manufacture, line speeds of the passing plastic film
are usually
limited to 150 feet per second. In the manufacture of the disclosed bag, line
speeds in the
range of 300 feet per second can be tolerated.
Hot seals produce permanent fusing of the plastic layers involved. Such
permanent fusing can be detected by trying to separate the joined film layers.
When such
an attempt is made to separate the two layers joined by a hot seal, either
joined film layer
tears. The "hot seal" - composed of two layers fused one to another - does not
tear and
remains in tact.
Regarding the use of a "cold seal", in the plastic bag manufacturing arts,
there has been known for many years a defective seal known as a "cold seal."
Such a cold
seal has here to fore been an imperfect hot seal. Usually, the imperfect hot
seal would be
located at the bottom of a plastic bag. When load was placed in the plastic
bag, the seal
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would part - and the bag contents drop to the ground, usually causing content
loss and
damage.
Cold seals as used in the specification that follows are easy to distinguish.
Where a cold seal is present, it imperfectly seals two plastic film layers
together. This
imperfect fusing can be easily recognized. Film separation at the cold seal
allows the two
imperfectly fused film layers to separate. Each layer separates from the other
layer
without loosing substantial structural integrity of the film. Unlike the
conventional "hot '
seal", neither of the previously fused film layers tears when separation
occurs.
Cold seals have been used with plastic bags for joining bags loosely in a
bundle. Such joinder usually takes place at the top of the bag adjacent the
opening. In
the typical application, separation of a bag from a bundle of bags at a cold
seal usually
assists in the opening of the bag.
Until this disclosure, no one has made a "cold seal" an important structural
element of a bag!
In addition to the "cold seal", this disclosure makes use of a preformed
"hinge" with the plastic film of the bag wall. Such hinges are capable of
rapid formation
by impressing the rapidly passing and planar film along a linear boundary.
This
impressing at the linear boundary leaves the film predisposed to "hinge" or
fold at the
boundary.
The hinge that is here utilized is to be distinguished from a "fold." In
folding, film is bent over and then creased so that it folds. Once this
bending and
creasing has occurred, the film is disposed to repeat the bending and folding
along the
crease.
The "hinge" here utilized is place in the plastic film of the bag wall while
the film is planar or in the "lay flat condition" and passes through the bag
machine at high
speed. The placed linear hinge is typically either at right angles to the
direction of film
motion or alternatively diagonal to film motion. Thus the hinge here used, is
not to be
confused with side gusset creases that result from creased folds made in the
direction of
film passage. When the film is hinged - for the first time from the lay flat
state to the
erect disposition of the bag - the hinge structure impressed in the film
predisposes the
film to bend along the hinge axis. Through the combination of the hinge
joining panels of
plastic across the multiple flat surfaces of an erect bag, sufficient
structural integrity is
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imparted to the bag to remain upright and open to receive and contain articles
- such as
fast food orders.
The reader should also understand that the difference between a "cold
seal" and a "hinge" is not always precise. For example, where plastic fiim is
passing a
5 die at relatively high speed, and the dye come down upon two or more layers
of plastic
film, a hybrid "cold seal and hinge" can result. The cold seal will be
recognizable by the
imperfect fusing of the plastic layers one to another. The hinge will be
recognizable by the reduction in thickness of the plastic film wall with the
increased tendency of the film
to fold at the hinge. It has been found that hybrid "cold seal" and "hinge"
structures are
produced in the bag production process herein set forth.
In the disclosure that follows, neither the "cold seal" nor the "hinge"
incorporate or refer to bending and creasing film so that the film may bend
again along
the bend or the crease. In both the cases of the "cold seal" and "hinge", the
film is at all
times flat and planar when the "cold seal" or "hinge" is applied and
introduced. This is
known as the "lay flat" condition.
SUMMARY OF THE INVENTION
An expandable plastic film gusseted bag includes a front panel of plastic
fihn having two substantially parallel side edges; and a rear panel of plastic
film having
two substantially parallel side edges. Two front panel gussets of plastic film
are used.
Each front panel gusset is connected to one of the two substantially parallel
side edges of
the front panel. Two rear panel gussets of plastic film are used. Each rear
panel gusset
connected to one of the two substantially parallel side edges of the rear
panel. As in
conventional bag manufacture, each front panel gusset connected to a rear
panel gusset
and usually each of the panel gussets are foldable between the front panel and
the rear
panel to provide a continuous bag periphery. A bottom joins the bottom of the
front
panel, rear panel, two rear panel gussets and two front panel gussets at
substantial right
angles to the side edges of the front panel, rear panel and gussets to close
the bottom of
the bag and leave only the top open. The improvement provides each plastic bag
with
eight first linear folding axes configured adjacent the bottom within each
front panel and
each front panel gusset and each rear panel and each rear panel gusset having
one first
linear folding axes. These folding axis extend from a joinder of a gusset at
the bottom to
the side edges of the front panel or the rear panel and the front panel gusset
or the rear
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panel gusset at an oblique angle in the range of 45 . The folding axes are
made by a
process restricted to a group consisting of either a cold seal, a hinge, or a
hybrid cold seal
and hinge being placed in the plastic film while the film is planar or in the
"lay flat"
disposition. On opening of the expandable gusseted bag, the bottom seal of the
bag
disposed adjacent the gussets forms a generally triangular shaped overlay
relative to the
gussets to form a square bottom bag.
A process for bag manufacture of a bag having a first dimension from a
sealed bottom of the bag to an open top of the bag, the bag being fabricated
from a
continuous tube of plastic film bag material. The process includes the steps
of providing
a continuous tube of plastic film bag material. The side edges of the bat
material are
folded between a front bag panel and a rear bag panel to form gussets.
Preferably, the
front bag panel and the rear bag panel are confronted to and in contact with
one another at
an inside surface of the front bag panel and the rear bag panel. A sealing
station having
apparatus for placing two parallel and spaced apart seals and a knife for
cutting the
continuous tube of the plastic film bag material between the two parallel and
spaced apart
seals. First adjacent double seals are formed across the front bag panel and
the rear bag
panel, the double seals in parallel side-by-side relation with one another
with the plastic
film bag material there between. These seals are cut across the continuous
tube of plastic
film bag material between the first adjacent double seals. The continuous tube
of plastic
film bag material is at least twice the first dimension from the sealed bottom
of the bag to
the open top of the bag. This forms second adjacent double seals across the
front bag
panel and the rear bag panel, the second adjacent double seals in parallel
side-by-side
relation with one another. By cutting the continuous tube of plastic film bag
material
between the second adjacent double seals, a double bag unit is formed and
severed having
single seals at opposite ends of the double bag unit with a continuous tube of
plastic film
bag material having two first dimensions between the single seals at opposite
ends of the
double bag unit.
A process of cold sealing two layers of plastic film material together is
used as part of the structural element of a plastic bag made from plastic
film. The plastic
bag is formed with a front panel having two substantially parallel side edges;
a rear panel
having two substantially parallel side edges; and a fastening of the front
panel and rear
panel for forming a continuous periphery to the bag. It is required the
plastic bag have a
bottom joining the bottom of the front panel, and the bottom of the rear panel
at
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substantial right angles to the side edges of the front panel and rear panel.
This imparts to
the bag a closed bottom, a continuous closed periphery, and an open top. The
improvement provides the bag with a cold seal, which cold seal does not form a
part of
the closed bottom and continuous closed periphery of the bag. In the improved
process, it
is required that the first and second plastic films of the bag be confronted
to one another
in a disposition for sealing. Compression dies are provided on at least one
side of the
juxtaposed first and second plastic films, the compression dies are provided
with the size
and shape of the cold seal desired. Impressing of the compression dies across
the
juxtaposed first and second plastic films occurs. This impressing is at a
temperature and
pressure sufficient to fuse the first and second plastic films together.
However, the
impressing has insufficient temperature and pressure to permanently fuse the
first and
second plastic films together so that the films when separated at the cold
seal each retain
structural integrity. Embodiments are set forth where the cold seal is used as
a structural
element to square out square bottom bags. Specifically, the cold seal is
provided with at
least a linear disposition, which imparts to the cold seal the predisposition
to fold or hinge
at the boundary to cause opening to the square bottom shape.
One of the most important applications of this cold seal is the placement
of a hinge. Specifically, two layers of plastic film are less than permanently
joined
together along a linear boundary. This joinder preferably occurs in the lay
flat disposition
while the bag is being manufactured. In this case, the cold seals are place
where hinging
of a square bottom plastic bag is required to predispose the bag to open with
a square
bottom.
When the bag is first opened by a clerk, the films joined at the top of the
bag are parted from the lay flat disposition. Specifically, the clerk parts
the front bag
panel and the rear bag panel adjacent the opening, and then pulls the bag
rapidly through
the air. When the films are parted and air is introduced into what will become
a square
bottom bag, parting of the opened tissue occurs until the air penetrating the
bag, reaches
the cold seal.
When the air reaches the cold seal, the joined bag walls no longer
separate. Instead, separation ceases at the cold seal and the material of the
bag hinges at
the cold seal. This hinging occurs because the bag continues to expand
responsive to the
in rush of air but is prevented by the cold seal from further separation at
the cold seal.
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Thus, the present invention refers to a simple process of cold sealing plastic
film
that results in substantially the same effect as the heat sealing methods
described in
LaFleur '077, Hummel '565 and Roan '262 and the adhesive bonded bag of Watkins
'829
(without the use of adhesive). It also relates to some of the resultant
plastic bag products,
more specifically flat bottom bags. However, the present invention reveals for
the first
time a means of cold sealing plastic film in a high-speed process with
superior qualities
than that provided by the aforementioned heat sealing or adhesive processes.
This cold
sealing process may be applied to the plastic bag film layers before it is cut
and sealed
into a bag of predetermined length, which then does not significantly affect
line speed.
Unlike the heat sealing methodology of La Fleur '077, Roen '262 and Hummel
'565
which requires controlling 4 individual heat seals per bag, the present
invention requires
only one simple operation per bag-which operation can be simultaneously
conducted on
3-5 lanes without significantly affecting line speed. Furthermore, this cold
seal
technology can be applied along with the hinging technology revealed in United
States
Patent No. 6,113,269 issued September 5, 2000 to the named inventor.
In these applications, hinges are used to produce a superior flat bottom,
stand up
bag. When doing so, the cold seals and the hinges are applied in the same
single
impressing operation. The reader will understand that the production of a
hybrid cold
seal and hinge is also possible. In this latter case, the imperfect joinder
between two film
layers also relates to the wall being thinned to form a hinge.
This cold sealing process is easily adapted to existing high-speed bag making
equipment and technology-both bottom seal and sideweld. The methodology of
applying angular cold seals to gussets also produces a seal that lies across
the entire
gusset pairs-right up to and even past the center gusset creases-which is
virtually
impossible with the prior art heat seal or adhesive technology. The present
invention cold
seal process applied to common plastic bags in a high-speed mode ensures great
accuracy
in consistently producing high quality, square bottom plastic bags that stand
up.
Applying the present invention as an angular gusset cold seal on the side
gussets
of bottom seal bags or the bottom gusset on sideweld bags gives a bag a
temporary bond.
This temporary bond enables the user to quickly find the bag bottom
i~.
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regardless of how he/she is opening and preparing the bag for use. With
angular cold
seals, the bottom portions of the side gussets on bottom seal bags will fold
upon
themselves, forming a flat base. Alternately, the cold seals may be applied to
the outside
portions of the bottom gusset on sideweld bags which portions will then fold
upon
themselves and form a flat base. Folding occurs whether this folding is by
capturing air
in a bag, shaking it, or by placing a hand inside the bag and pushing the
gussets down at
the bottom, the result is the same--a bag manufactured in the lay flat state
that squares out
and tends to stand up. It will be noted that the cold seals here disclosed may
lose their
bond after some repetitive reuse. However, plastic bags have a one time use
requirement,
especially the typical bags used in supermarkets, fast food chains and so on.
Generally
speaking, these carry out and point of purchase bags are only opened and
filled one time.
For instance, a bag used in a fast food restaurant is only filled once; a bag
used for as a
point of purchase bag for cookies is only filled once at the cookie factory.
The present invention also reveals for the first time a means of
impressing hinges and temporarily cold sealing plastic film that can be
precisely
executed so that the impressions and temporary seals are accurately applied to
predetermined panels or bag plies. Furthermore, the process of the present
invention will
reveal that these impressions and temporary seals may be perfectly registered
as required
in the bag making process.
When impressing hinges and temporary cold seals to form stand up style
bags, it is typically applied to the film in its lay flat condition, which--
unlike prior art--
entirely eliminates the cumbersome, time consuming folding methodologies or
the heat
sealing processes previously discussed. Furthermore, hinge impressing and
temporary
cold sealing are easily adapted to existing high-speed bag making equipment
and
technology--both bottom seal and side weld--and can be placed on multiple
lanes without
substantially affecting line speed. The process of applying hinging by cold
seals may also
be done simultaneously during one single impressing operation. The impressing
and
temporary seal processes can be applied to common plastic bags at present day
high
speeds and with great accuracy to consistently produce high quality, square
bottom plastic
bags that stand up.
The process of the present invention opens up new possibilities in the
use of cold seal technology in the plastic bag and film industry. For
instance, the hinging
effect is also a reliable means to create new bag shapes and bottom
configurations, such
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as bags with flat, octagonal, hexagonal or decagonal bottoms. As discussed in
cross
reference, hinges can cause the bottom portions of the side gussets on bottom
seal bags
will fold down upon themselves, forming a flat base. Or, hinges may be applied
to the
outside portions of the bottom gusset on side weld bags which portions will
then fold out
upon themselves and form a flat base. Used in concert with cold or warm
temporary
seals, the reliability in performance of the product may be significantly
improved.
Impressed hinges with accompanying cold or warm temporary seals can cause side
weld
bags to stand more upright and erect with their side welded ends folding
inward, forming
a squarer bag shape and improving the ability to load the bag.
In this application, the impressing effect can also form an aesthetically
appealing,
registered embossing of a logo. The possibilities are endless.
The process of the present invention can also be reliably applied to laminated
films and films that may be a combination plastic film and other materials
such as foil or
paper, for instance those used in point-of-purchase packaging. Many laminated
films are
made of a thin layer of foil with a plastic outer or inner layer, frequently
polyethylene.
The two key variables in applying the present invention with films other than
polyethylene are the temperature and the amount of pressure applied.
The impressing of hinges and applying cold or warm temporary seals is
typically
accomplished by applying pressure to a die upon a flat or round platen-or a
die upon a
matching, cooperating die-which in between lies one or more layers of plastic
film. The
process may also be effectively accomplished by the means of pressure
embossing
between rollers, one or more of which has a die impressing means. By using
various
combinations of dies, for instance male and female, male and male, two males
and two
females and so on various effects may be created. With heat being applied to
the dies or
rollers to create warm temperatures, the hinge or the temporary seal processes
of the
present invention are fast and highly effective and can easily keep up with
the fastest high
speed bag machines in the world.
A hinge is disclosed for a plastic film. This film has a predetermined
thickness
sufficient for the plastic film to remain planar in an absence of a first
bending
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moment applied across the plastic film. The hinge includes at least one linear
groove
configured in the plastic film to reduce the predetermined thickness of the
plastic film at
the linear groove. The hinge permits preferential hinging of the plastic film
at the linear
groove responsive to a bending moment at the linear groove across the plastic
film less
than the first bending moment. The linear groove has insufficient depth to
sever the
plastic film and enables the hinge film to retain sufficient remaining
thickness at the
linear groove to permit hinging and not tearing of the plastic film at the
linear groove.
When the hinge is placed across a plastic film, and the film bent at the
hinge, the film
defines a first panel and a second panel with each panel disposed at an angle
to one
another at the hinge. This allows the first panel and the second panel to form
a three
dimensional structure to maintain the plastic film of each panel against
bending. A
square bottom bag design is disclosed where the hinge predisposes a plastic
bag to open
with a square bottom.
The present invention relates to simple process of hinging plastic film that
results in substantially the same effect of the creasing or folding or heat
sealing of plastic
film discussed in the Description of Prior Art. Unlike the Prior Art, the
hinge may be
impressed in plastic film at relatively high speed. In this embodiment, a
linear die may
impart the required groove to plastic film as it passes at relatively high
speed (about 300
feet per second).
This process also is useful with plastic bag products. For example, the
film can have a hinge precisely located at an angle to the direction of the
passing film.
The present invention reveals for the first time a means of hinging plastic
film that can
effect a unidirectional or bidirectional folding ability depending upon the
desired effect.
This hinging process may be applied to the plastic bag film before it is cut
and sealed into
a bag of predetermined length, which then does not significantly affect line
speed. It is
typically applied to the film in its layflat condition, which--unlike prior
art--entirely
eliminates the cumbersome, time consuming folding methodologies or the heat
sealing
processes previously discussed. Furthermore, this hinging process is easily
adapted to
existing high-speed bag making equipment and technology--both bottom seal and
sideweld--and can be placed on multiple lanes without substantially affecting
line speed.
This hinging process can be applied to common plastic bags in a high-speed
mode and
ensures great accuracy to consistently produce high quality, square bottom
plastic bags
that stand up.
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The present invention also reveals new possibilities in the use of this
technology in the plastic bag and film industry. For instance, the hinging
effect can be
used to create new bag shapes and bottom configurations, such as flat or
square bottom
bags and bags with octagonal bottoms. With the hinges, the bottom portions of
the side
gussets on bottom seal bags will fold down upon themselves, forrniing a flat
base. Or,
hinges may be applied to the outside portions of the bottom gusset on sideweld
bags
which portions will then fold out upon themselves and form a flat base. The
hinges can'
cause sideweld bags to stand more upright and erect with their sidewelded ends
tuming
inward, which forms a squarer bag shape and improving the ability to load the
bag. The
hinging effect can also be used to cause bottom seals to fold under when
desirable and
can cause bags to stand up more erect. The hinging effect can used to make
predetermined structural creases to give bags more vertical rigidity and may
also be used
to make bag closures in a pre-determined location. The hinging effect can even
be done
to impress an aesthetically appealing, registered embossing of a logo. The
possibilities
are many.
When applied to square-bottom or stand up bags, bottom seal or sideweld,
the hinge preferentially enables the bag to open and dispose the square bottom
to a
counter surface. At least through the action of the hinges, the plastic bag is
disposed to
stand open and upright while in the empty state. The user can quickly find the
bag
bottom regardless of how he/she is opening and preparing the bag for use.
Whether this
preparation for use be by capturing air in a bag, shaking it, or by placing a
hand inside the
bag and pushing the gussets down at the bottom, the result is the same--a bag
that squares
out at the bottom and tends to stands up.
The hinge can also be reliably applied to laminated films and films that
may be a blend of plastic and other materials such as foil or paper, for
instance those used
in point-of purchase displays. Many laminated films are made of a thin layer
of foil with
a plastic outer or inner layer. By applying the present invention to these
types of films,
the result is the same, a square bottom bag. Creating square or rectangular
packages of
this nature would result in a substantial savings of shipping costs and shelf
space, as more
square packages can be packed in a given carton size than round packages.
The hinging process is typically accomplished by applying pressure to a
die upon a platen--or a die upon a matching, cooperating die--which in between
lies one
or more layers of plastic film. Using various combinations of dies, for
instance male and
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female, male and male, two males and two females and so on, various effects
may be
created.
For ease of explanation, only some of the particular uses of the present
invention will be revealed herein, however, it would be easy for anyone
trained in the art
to find other applications, which would fall under the scope of the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic representation of a "cold seal" apparatus illustrating
the diagonal placement of cold seal in rapidly passing planar film for causing
the
"imperfect" joinder of two layers of bag material;
Fig. 2 illustrates the separation of two "imperfectly fused" joined layers
illustrating that upon separation of the layers that each of the separated
layers retains its
structural integrity;
Fig. 3 illustrates a "hinge" as it is here defined being placed within a
plastic bag wall while the film is disposed in a planar condition;
Fig. 4 is a expanded side elevation section of the plastic film at the hinge
illustrating the linear impression in the plastic film which leave the film
when folded for
the first time with the predisposition to fold along the linear axes of the
fold;
Fig. 5 is a side elevation view of the plastic bag article of this invention
illustrating in particular the placement of the "folding axes" (either hinges,
cold seals, or
both) in the side wall of a flat bottom plastic bag predisposing the bag to
open and "flat
out" when used for the first time;
Fig. 6 is a perspective view of the bag of Fig. 5 being opened and
"flattened out" for the placement of articles into the bag;
Fig. 7 is a so-called "side weld" bag shown having the hinge axes of this
invention; and,
Fig. 8 is the side weld bag of Fig. 7 in the open disposition.
Fig. 9is a plan view of a prior art process, which illustrates a typical
bottom seal bag manufacturing process.
Fig. 10 a plan view of a prior art process, which illustrates a typical
sideweld bag manufacturing process.
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Fig. 11 s a plan view of the present invention, which shows the process of
die cutting preformed plastic tubes that are sealed at both ends, into
independent stacks of
common bottom sealed plastic bags.
Fig. 12 is a plan view of the present invention of Fig. 3, which shows the
process of transferring the die cut stacks to a packing location.
Fig. 13 is a partial plan view of another means of transferring the two side-
by-side bag stacks to a conveyor.
Fig. 14 is a partial plan view of a means of transferring the two severed
and sealed portions through a two-step die-cutting operation.
Fig. 15 is a plan view of a severed and sealed portion being die cut into
two bag packs with die cut handles and a sculptured top made as made by the
process of
the present invention.
Fig. 16 is a plan view of a severed and sealed portion being die cut into
two bag packs with double extended portions above the bag mouth as made by the
process of the present invention.
Fig. 17 is a plan view of a severed and sealed portion being die cut into
two bag packs with single extended portions above the bag mouth which single
portions
are offset on the opposing bag mouths of the bag packs, as made by the process
of the
present invention.
Fig. 18 is a plan view of the present invention as it may be applied to the
process of making plastic T-shirt style, handled grocery sacks.
Fig. 19 is a plan view of the present invention, which shows the process of
die cutting preformed plastic tubes sealed at both leading and trailing edges,
into
independent stacks of common plastic sideweld bags with die cut handles.
Fig. 20A is a partial plan view showing the application of angular bottom
seals used to isolate the holes in the bag bottom created by a pin stacking
process.
Fig. 20B illustrates the bag unit of Fig. 12A used for filling with cement or
other granular contents through a pneumatic filling aperture.
Fig. 21 is an apparatus for imparting a slit seal across the bag material.
Fig. 22 illustrates apparatus for imparting a broad conventional hot seal.
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14A
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
Referring to Fig. 1, double bag unit D is shown passing along bag
production line B. This double bag unit D is sealed at both ends along leading
seal S I
CA 02304215 2006-10-24
and trailing seal S2. As will herein after be made clear, eventually, double
bag unit D will
be severed medial at medial cut C. This severance will allow an opening for
each bag of
the double bag unit D to occur in the center with flat bottoms at each end.
Double bag unit D is a gusseted bag construction. As such gussets are attached
between front panel P and rear panel R, they may be seen expanded in the view
of Fig. 6.
as front and rear panel gussets 64 and 66 respectively. The reader will
understand that the
schematic of Fig. 1 is for the purpose of illustrating the placement of cold
seals 20 and 21.
All other features of the bag construction have been omitted.
Returning to Fig. 6, a typical flat bottom bag is illustrated. This includes
the
placement of cold seals or hinges 70 at the bottom portion of the illustrated
and expanded
bag. It will be developed that the hinging of the flat bottom bag illustrated
in Fig. 6 can
either be a hinge or a cold seal. For the purposes of Fig. 1 and 2, only the
cold seals 21,
22 are considered.
Returning to Fig. 1, it is seen that die 24 having cold seal impressing ridges
25 and
26 overlies double bag unit D. For the purposes of Fig. 1, die 24 has been
rotated up and
away from double bag unit D so that ridges 25 and 26 are plainly visible. As
is
schematically illustrated, die 24 impresses on platten 22 with double bag unit
D captured
there between. Impressing of die 24 may be heated or done in the cold state.
In any event
there is an imperfect joinder of at least two layers of plastic material. To
understand how
this imperfect joinder operates, the readers attention is invited to Fig. 2.
Referring to Fig. 2, two plastic layers 27, 28 are being separated from one
another.
Such separation easily occurs until cold seal 21 is reached. At cold seal 21,
it will be
found that the respective layers 27, 28 are imperfectly joined to one another.
Easy
separation will stop along the boundary of cold seal 21.
If one continues to try and separate respective layers 27, 28 beyond cold seal
21,
such separation will eventually be successful. Separation will occur to seal
21. Both
respective plastic layers 27, and 28 will maintain their structural integrity.
In the usual
case, the broken cold seal will not appreciably weaken the layers 27, 28.
A brief preview of how cold seal/hinge 70 functions to allow the opening of a
flat
bottom bag is in order with quick reference to Fig. 6. Referring briefly to
Fig. 5, and then
to Fig. 6, it will be seen that when the flat bottom bag, cold seal represents
a point of
increased resistance only to opening of the bag. This is sufficient to cause
the bottom of
the bag to "flat out" during the opening process.
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16
I have also discovered that the placement of a hinge in location 70 of the
illustrated flat bottom bag has the same effect. Specifically, and referring
to Fig. 3,
plastic film 28 is impressed with hinge H. Impression occurs between die 40
and platten
42. As before, die 40 has ridge 41 extending across the bottom of the die in
the path of
hinge H. Again, the path of hinge H is linear and constitutes a reduction in
thickness of
film 28 along the axis of hinge H.
Refer again to Figs. 5 and 6. Assume that instead of cold seals 20, 21,
hinge H is placed at cold seal/hinge 70 at the bottom of flat bottom bag.
Again squaring
of the bag B will occur. In other words, either a cold seal such as cold seals
20, 21 or
hinge H will predispose the bag article of Fig. 5 to open as the flat bottom
bag illustrated
in Fig. 6.
Taking the case of the open flat bottom bag, it will be remembered that the
production here illustrated fonms the bag completely in flat and planar state.
When the
bag moves to the disposition shown in Fig. 6, the bag is opened for the first
time. This
being the case, it will be realized that cold seal/hinge 70 need only be
highly transitory.
In short, they need to work only once.
Further, it will be understood that both the cold seal and the illustrated
hinge do not have to have the full strength of the plastic film to operate
satisfactorily. All
that needs to happen is to have their respective formation add to the bag the
predisposition to open and flat out at the bottom. Once this is achieved, the
bag can be
conventionally loaded and conventionally used.
It should be understood that the hinge or cold seal used with this invention
can be hybrid. In this case, impressing of a cold seal may reduce the
thickness of the
plastic film giving the bag a tendency to "hinge" along the cold seal. At the
same time,
the vicinity of the hirige may result in an imperfect bond along the linear
hinge axis with
adjoining sheets of plastic film. This imperfect bond coupled with the "hinge
effect"
causes the film processed in the "lay flat" disposition to open and form
preferentially a
flat bottom contour.
Having said this much, the remaining structure of the illustrated bag can be
described. Turning Fig. 5, the bag has open top 62, front panel 63, front
panel gussets 64,
66 with central gusset fold 74, 80. The bag includes sealed bottom 68-72. In
accordance
- with the preferred embodiment, hinges 65, 75 are impressed in the bag front
pane163 and
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17
rear pane162. These hinges have been shown to react to a panel type hinging to
impart
additional strength to the bag.
Referring to Fig. 6, the open bag is shown with its flat bottom. It includes
gussets 64, 66 extending between front panel 63 and rear pane162. It will be
seen that
these respective gussets 64, 66 are in the full open position imparting to the
bag a flat
profile from the opening toward the bag bottom. At the bag bottom,
characteristic
triangular folds 90will form. These characteristic folds dispose the bag with
its flat
bottom resting downward. In fact, after opening an empty bag from the
disposition
shown in Fig. 5, to that of Fig. 6, it has been demonstrated that the bag
physically rests in
the disposition of Fig. 6. In short, a clerk may load the open bag at the
bottom without
fear of bag collapse to the closed position.
In Fig. 7 side weld bag 200 has a top 202, a front pane1203, a rear panel
(not shown), a die cut handle 205, a bottom gusset 204 and its center gusset
crease 206,
and side welded edges 208 and 210. At 45 degree angles in both outer regions
of bottom
gusset 204 are hinge axes 212 and 214 which respectively terminate
approximately at the
point where center crease 206 crosses side weld 208 and where center crease
206 crosses
side weld 210. A vertical bi-directional hinge 216 begins at point 218 and
terminates at
point 220 and another bi-directional hinge 222 begins at point 224 and ends at
point 226,
both of which hinges have been impressed upon front wa11203, rear bag wall
(not shown)
and bottom gusset 204.
In Fig. 8, the side weld bag 200 of Fig. 7 has been opened and sets upright
upon bottom gusset 204, Linear hinge axes 212 and 214 cause the lower outer
regions
230 and 232 respectively to turn upright and help flat out the bottom gusset
assisting in
the formation of a flat base. In turn, bi-directional hinge 216 causes the
upper outer
region 234 to stand up and box out and side weld 208 to cooperate by turning
inward.
Hinge 222 causes its respective upper outer region 236 to stand up and box out
and side
weld 210 to cooperate by turning inward. Bag 200 is now ready to be loaded.
It is easy to see that cold sealing the bottom gusset in side weld bags has a
similar outcome as cold sealing the side gussets in bottom seal bags described
in Figs. 5,
and 6.
Some attention should be given to the linear hinge axis which is at an
oblique angle - most preferably 45 . It will be understood that variations in
this angle can
occur. For example, the angle can easily vary in the range of 40 to 50 .
Further, both of
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18
the oblique axes do not have to be identical. They may each vary by differing
amounts.
All that is required is that the axes produce a tendency of the bag which is
manufactured
in the lay flat condition to hinge and open with a flattened out bottom.
In Fig. 9 the prior art bottom seal process begins with a flattened tube T,
which is
slit sealed S into two smaller flattened tubes T' and T", which smaller tubes
are side
gusseted at locations G' and G". After each individual bag is bottom sealed
and severed at
bottom seal bar B1, the bags are stacked up at location L' and L", which
stacks (typically
of 50 bags or so) are grasped by fingers sets F' and F" and transported to die-
cutting
station C1. After die cutting, the bag stacks are typically moved to a
conveyor belt or
packing station, in which the die cut bag stacks are loaded into shipping
cartons. In this
prior art example the bags being manufactured are die-cut handled Dual-tab
bags like
those described in U.S. Patent 4,759,639.
In Fig. 10 prior art sideweld process begins with a flattened tube T which is
slit
open at edge E, bottom gusseted P, which tube T is then sidewelded Dl into
individual
bags, which bags are stacked up at location M. These bag stacks are typically
picked up
by an employee who may die cut the bag stack at manual die cutting press N, in
this
illustration forming die cut handles H1 and sculptured shoulders V' and V".
In Fig. 11 the present invention bottom seal process begins with a flattened
tube
110, which is slit sealed by slit-seal knife 112 into two smaller flattened
tubes 114 and
114', which smaller tubes 114 and 114' are then side gusseted 116 and 118 and
116' and
118' respectively. Tubes 114 and 114' are then fed through bottom sealer 120
which sealer
120 makes two lateral seals (not shown) across tubes 114 and 114' and
simultaneously
severs tubes 114 and 114' between the two seals, creating two side-by-side,
severed and
sealed portions 122 and 122', which portions have been transported forward and
stacked
up, typically into stacks of 50 or so. Severed and sealed portions 122 and 122
have lateral
seals 124 and 126 and 124' and 126' respectively at both ends and gussets 116a
and 118a
and 116a' and 118a' respectively on their sides. One step forward in the
process, two side-
by-side severed and sealed portions have been transported by clamping fingers
142 and
144 and 142' and 144' respectively, to an intermediate point under die cutter
130, which
die cutter 130 is shown as having die cut the two side-by-side severed and
sealed portions
into four individual bag stacks 132a and 132b and 132a' and 132b' by knife 131
and has
die cut handles holes 133a, 133b, 133a' and 133b' respectively. Each bag stack
132a,
132b, 132a' and 132b' has side gussets 136a and 138a,
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19
136b and 138b, 136a' and 138a', and 136b' and 138b' respectively, and lateral
seals 134,
136, 134' and 136' respectively, which lateral seals have formed bag bottoms
140a, 140b,
140a' and 140b'. From this die cut operation, the bag stacks 132a, 132b, 132a'
and 132b'
would be transported to a loading station. This illustration shows that two
slit sealed
tubes can be made into four bag packs during a single cycle of the bag
machine's
operation. It also illustrates that the die cutting operation has the
tremendous flexibility
of creating virtually any style of bag and is not limited to interconnected,
detachable bags.
For instance, in addition to detachable bags, it may form bags with flush tops
and no
handles, bags with die cut handles, bags with sculptured shoulders, bags with
a multitude
of tab designs, T-shirt style plastic grocery sacks and so on. As is further
described in the
following Fig. 12, the continued process of the present invention will also
eliminate the
need or the extra labor required to tear apart interconnected detachable bags
at a
weakened tear line. It should also be understood that the process of the
present invention
may be applied to a tube that has been slit sealed into more than just two
smaller tubes,
for instance, three, four or even five tubes. In such a case, three, four or
five tubes would
then be converted into six, eight or ten individual bag stacks.
In Fig. 12 the process of Fig. 11 shows bag stacks 132b and 132b' have
been already transported from the die cutter 130 to a packing station by
fingers 142, 144,
142' and 144' respectively (see Fig. 11 to view location of Fingers 142, 144,
142' and 144'
just before the transportation of bags stacks 132b and 132b'). Fingers 142,
144, 142' and
144' are now shown in position to grasp the second sets of bag stacks 132a and
132a',
which bag stacks will also be transported to the same packing station where
bag stacks
132b and 132b presently lie. Fingers 142, 144, 142' and 144' are typically a
part of a
movable carriage system that grasps and transports bags along the production
line. In the
process of the present invention, the fingers and carriage system will cycle
twice during
any one die cutting operation instead of only once, as would be the case with
prior art.
In Fig. 13 a variation on transporting the bag stacks is illustrated by four
sets of fingers, which fingers 152a and 154a grasp bag stack 132a, fingers-
152b and 154b
grasp bag stack 132b, fingers 152a' and 154a' grasp bag stack 132a', and
fingers 152b' and
154b' grasp bag stack 132b', all of which fingers and bags stacks are
simultaneously
transported to a packing station (not shown). It is important to note that
there are other
transportation possibilities in the process of the present invention, for
instance, the bag
stacks may be grasped by two sets of fingers in which each set grasps two
stacks
CA 02304215 2006-10-24
simultaneously. The present invention is not intended to be limited by the
means of bag
stack transport.
In Fig. 14 two severed and sealed portions 162 and 162' have been transported
to
an intermediate point at first die cutting station 164 in which die cut handle
holes 166 and
168 and edge portions 170 and 172 have been cut and extracted (handle hole
slugs not
shown) from severed and sealed portion 162, and; die cut handles 166' and 168'
and edge
portions 170' and 172' have been cut and extracted (handle hole slugs not
shown) from
severed and sealed portion 162'. Severed and sealed portions 162 and 162'
remain
connected via bridges 173 and 173' respectively. The arrows then show the same
two
severed and sealed portions 162 and 162' as they have been subsequently
transported
(arrows) by fingers 175a and 175b, and 175a' and 175b' respectively, to an
intermediate
point at second die cutting station 174 in which knives 176 and 176' of die
cutting station
174 have severed the two portions 162 and 162' at their respective bridges 173
and 173'
(before severance) forming four individual bag stacks 162a, 162b, 162a' and
162b'. This
second die cutting operation is conducted near the bag packaging station, to
which the
bag stacks may be easily delivered by fingers to a conveyor belt or even
dropped right
upon the conveyor belt once severed. Or, the bag stacks themselves may be
dropped
directly on the belt itself or even manually removed from the second die
cutting station
and packed into shipping cartons. In this two-step operation, it is also ideal
for heat
sealing tabs if desirable, or releasably bonding bag packs as discussed in
United States
Patent No. 6,171,226 issued January 9, 2001 to the named inventor.
In Fig. 15 severed and sealed tube portion 180 has opposing bottom seals 182
and
184 and has been die cut at an intermediate point to form opposing bag tops
186 and 188,
die cut handles 190 and 192, and sculptured shoulders 194 and 196 and 194' and
196', all
together which form two opposing bag stacks 182a and 182b. In the center of
the
opposing bag tops 186 and 188 and the opposing sculptured shoulders 194 and
196 and
194' and 196' is slug 198 (shade lines), which is a result of the die cutting
operation.
After the die cutting operation has been completed, slug 198 and slugs 191 and
193
(shade lines) formed from the die cutting of handles 190 and 192 are all
typically pushed
into a recycling (or reprocessing) bin, which contents are later reprocessed
into finished
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21
product. From this die cutting operation, the bag stacks are transported as
previously
described to a packing station.
In Fig. 16 severed and sealed tube portion 300 has opposing bottom seals 302
and
304 and has been die cut at an intermediate point to form opposing bag tops
306 and 308
and double extended portions 310, 310', 312, and 312' at the opposing bag tops
306 and
308 respectively, all together which form two opposing bag stacks 302a and
302b. The
extended portions 310, 310', 312 and 312' are down separated and defined by
cut lines
314 and 314' respectively, which cut lines may have been made from either the
single or
two-step die cutting process previously described. In the center of the
extended portions
310, 310', 312 and 312' are mounting holes 316, 318, 316' and 318'
respectively. Slugs
320, 322 and 324 (shaded lines) will be removed and reprocessed once again in
the same
manner as previously discussed. These bags with double extended portions have
been
made according to United States Patent No. 6,171,226 issued January 9, 2001 to
the
named inventor.
Fig. 17 severed and sealed tube portion 330 has opposing bottom seals 332 and
334 and has been die cut at an intermediate point to form opposing bag tops
336 and 338
and single off-set extended portions 340 and 342 at the opposing bag tops 336
and 338
respectively, all together which form two opposing bag stacks 332a and 332b.
The
extended portions 330 and 332 are down separated by cut line 334a, which cut
line may
have been made from either the single or two-step die cutting process
previously
described. In the center of the extended portions 330 and 332 are mounting
holes 346 and
348 respectively. Slugs 350 and 352 (shaded lines) will be removed and
reprocessed in
the same manner as previously discussed. These bags with single extended
portions have
been made according to United States Patent No. 6,171,226 issued January 9,
2001 to the
named inventor.
In Fig. 18 the present invention bottom seal process beings with a flattened
tube
460, which is slit sealed by slit-seal knife 462 into two smaller flattened
tubes 464
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22
and 464', which smaller tubes 464 and 464' are then side gusseted 466 and 468
and 466'
and 468' respectively. At seal location 469, gusseted tubes 414 and 414' are
sealed
laterally at 471a, 471b, 473a and 473b, and 471a', 471b', 473a' and 473b'
respectively.
These lateral seals 471a, 471b, 473a and 4173b, and 471a', 471b', 473a' and
473b' traverse
the gussets 466, 468 and 466' and 468' as illustrated. Tubes 464 and 464' are
then fed
through bottom sealer 470, which sealer 470 makes two more lateral seals (not
shown)
across the entire width of tubes 414 and 414' entirely and simultaneously
severs tubes 414
and 414' between the two seals, creating two side-by-side, severed and sealed
portions
472 and 472', which portions respectively have lateral seals 471a, 471a, 471b,
473a and
473b, and 471a', 471b', 473a' and 473b' at an intermediate location and which
severed and
sealed portions 472 and 472' are stacked up into a typical stack of 50 bags or
so. As
illustrated, stacked up severed and sealed portions 472 and 472' have lateral
seals 474 and
476, and 474' and 476' respectively, at their ends, which lateral seals were
made at bottom
sealer 470 and extend across the entire width of the portions 472 and 472',
and; portions
472 and 472' have gussets 466a and 468a and 466a' and 468a' respectively on
their sides.
One step forward in the process, the two side-by-side severed and sealed
portions have
been transported by any of the means previously described to an intermediate
point under
die cutter 480, which die cutter 480 is shown as having die cut the two side-
by-side
severed and sealed portions into four individual bag stacks 482a and 482b and
482a' and
482b' (shown in its view after being die cut and as separated from the die cut
operation)
by rectangular central die cut knives 481 a and 481b (not shown) and their
respective
blades 483a and 485a, and 483b and 484b (not shown), which blades 483a and
485a are
shown cutting right in between the two pairs of lateral seals 471a and 471b
and 473a and
473b. Die cuts 481a and 481b have formed handled T-shirt style bags much like
those
described in U.S. Patent 4,676,378 Baxley, with outer opposing strap handles Y
and a
central bag mouth region Z. Die cutting this type of bag pack may be done in
either a
single or two-step die cutting operation. The die cut between the lateral
seals (as shown
in 483a and 485a) forming the haiidles may also be done at the sealing station
469. What
is most important is to illustrate that the two slit sealed tubes can be made
into four bag
packs and also illustrates the tremendous flexibility of forming various bag
styles without
interconnecting the bags with a weakened tear line. It should be u:nderstood
that this bag
making process may also be applied to a tube that has been slit sealed into
more than just
two smaller tubes, for instance, three, four or even five tubes. In such a
case, three, four
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23
or five tubes would then be converted into six, eight or ten individual bag
stacks. In
forming plastic grocery sacks of this style, using a two-step die cutting
process may also
be advantageous. The first step may die cut the handle portions thereby
forming the two
side-by-side bag packs, and the second step may sever the bag packs entirely
while
simultaneously releasably bonding the bag packs together.
In Fig. 19 the present invention sideweld process begins with a flattened
tube 510, which is then gusseted 516 and 518 respectively. Tube 510 is then
fed through
bottom sealer 520 which sealer 520 makes two lateral seals (shown as sealed
side edges
521 and 523) which seals 521 and 523 simultaneously cuts tube 510 into severed
and
sealed portion 522, which portion 522 has been stacked up into a stack of
typically 50
bags or so. Severed and sealed portion 522 now has lateral seals 521 and 523
on its side
regions and gussets 516 and 518 on its outer top and bottom regions. One step
forward in
the process, the severed and sealed portion 522 is shown transported to an
intermediate
point under die cutter 530, which die cutter 530 is shown as having die cut
the severed
and sealed portion 522 into two individual bag stacks 532a and 532b at cut
line 534,
which bag stacks 532a and 532b have die cut handles holes 533a and 533b
respectively.
Each bag stack 532a and 532b has bottom gussets 536a and 536b respectively,
and lateral
sealed edges 538a and 539a and 538b and 539b respectively, and die cut line
534 has
formed two bag tops 540a and 540b respectively. From this die cut operation,
the bag
stacks 532a and 532b would be transported to a loading station by fingers 546a
and 548a,
and 546b and 548b respectively, as shown in the sequence. The bag stack
transportation
means may be any of those previously described. This illustration shows that a
single
sidewelded tube can be made into two bag packs during a single cycle of the
bag
machine's operation. It also illustrates the tremendous flexibility of the die
cutting
operation, fonning virtually any style sideweld bag and also is not limited to
interconnecting the bags. For instance, in addition to sideweld bags
illustrated, they may
have flush tops and no handles, may have sculptured shoulders with handles,
and may
even be a form of T-shirt bag. In a similar manner as has been previously
described the
sideweld process of the present invention may also be applied to two, three,
four or even
five tubes. In such a case, three, four or five tubes would then be converted
into six, eight
or ten individual bag stacks.
In Fig. 20A severed and sealed bag portion 550 is shown after it has left
bag bottom sealer 552 and stacked up on stacking pins 554 and 556. At the
lower outer
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24
corners of severed and sealed bag portion 550 are angular seals 558, 560, 562
and 564.
These seals may have been made much like those described in U.S. Patent
3,915,007
LaFleur, or in United States Patent No. 6,139,184 issued November 20, 2001 to
the
named inventor.
Angular seals 558 and 560 serve to confine the holes made by stacking pins 554
and 556 into the outer portions 566 and 568. These outer portions 566 and 568
will be
located at the eventual bag bottoms underneath the folded over gussets and are
not
vulnerable to stress when the bag will be subsequently loaded, which
therefore, the holes
formed at stacking pin locations 554 and 556 will not be vulnerable to
breaking when
placed under load. The isolation of stacking pins may be accomplished in a
variety of
means, but the one illustrated in Fig. 20A would be a preferred means, since
the angle
seals also provide a desirable, primary function. One of the keys to the
process of the
present invention with pin stacking systems, is to place the pin stacking
means towards
the outer, lower regions where the holes could then be isolated and not be
vulnerable to
tearing under stress-unlike being located in the middle region where pin
stacking holes
would readily tear once the final bag product were placed under load. It will
be seen that
outer portions 566 and 568 meet this condition of being subject to tearing
when the bag is
loaded. Similarly, the portions of the front panel can meet this limitation.
Fig. 20B illustrates an interesting bag unit. Specifically by placing a
pneumatic
nozzle 569, the bag unit of Fig. 20A can be filled as illustrated in Fig. 20B.
Filling occurs
in - for example - triangular portion 256 - with the triangular portion being
severed for
hinge like motion with respect to the double bag unit. Later, when the double
bag unit is
filled and stacked, triangular portion 556 hinges closed under the force of
cement trying
to escape the bag. A self seal bag unit results.
Referring to Figs. 21 and 22, two types of seals are illustrated. Referring to
Fig.
21, a known seal called a slit seal is illustrated. Knife-edge 600 heated
between 400 and
1000 degrees F periodically comes down on roller 602 with bag material 608
passing
between the knife-edge and roller. This leaves two seal beads 604, 606 sealing
the
bottom of the respective bags. Similarly, and in Fig. 22, a broad conventional
hot seal is
impressed by heated bar 610 on plated 612 on bag material 608. The broad heat
seal
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610 results. This broad heat seal is cut by down stream knife 613. Naturally,
various
other combinations of seal and knives will work with this described invention.
From the foregoing descriptions of the process and the many applications
of using the process of the present invention, as illustrated in both bottom
seal and
5 sideweld applications, it will be appreciated that the number of new
applications are
many. It is not the intention of the present invention to be limited solely to
the film
products illustrated herein or to the two individual processes, but to be used
in whatever
conceivable manner to improve the performance of a plastic bag, sheet, film,
laminated
film, or blended film manufacturing processes. For instance, any of the
processes
10 described herein may be used in lap seal or certain pouch applications as
well.
It should also be understood that the means of stacking bags may include
any number of possibilities, such as pin stacking, clamping, containing,
paddlewheel
stacking and so on. The result is still substantially the same as described
herein.
Furthermore, it should also be understood that the means of transporting
15 the bag stacks from and to die cutter and packing station may be any number
of already
acceptable means such as clamping with fingers on carriages, paddlewheel
transport,
conveyor belts and so on.
