Note: Descriptions are shown in the official language in which they were submitted.
CA 02333754 2000-11-30
WO 99/62768 PCT/US99/12110
TAMPER RESISTANT CLOSURE
TECHNICAL FIELD
The invention relates to a tamper resistant closure attachment accessory to a
machine
for wrapping a ribbon around the gathered neck of a bag and twisting the
ribbon for closing
and sealing the neck of the flexible bag.
BACKGROUND OF INVENTION
U. S. Patent No. 3,138,904 entitled "METHOD AND APPARATUS FOR TYING
PACKAGES AND WRAPPING MATERIALS;" U. S. Patent No. 3,059,670 entitled "WIRE
TWISTING TOOL;" U. S. Patent No. 3,919,829 entitled "APPARATUS FOR TYING
PACKAGES AND WRAPPING MATERIALS;" U. S. Patent No. 4,856,258 entitled "WIRE
TYING DEVICE;" and U. S. Patent No. 5,483,134 entitled "RIBBON SENSING DEVICE
FOR BAG TYER" disclose apparatus used for closing a plastic bag by attaching
and twisting
a wire-like ribbon about the neck of the bag.
Bag tying devices of the type disclosed in the aforementioned patents are
commercially
available from Burford Corporation of Maysville, Oklahoma. The tying devices
are generally
constructed to receive packages such as loaves of bread at speeds of for
example over one
hundred (100) packages per minute at speeds of about 108 feet per minute.
Plastic bags containing bakery products, paper plates and ice are easily
opened by
removing the twisted ribbon from about the neck of the bag so that the
contents of the bag are
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CA 02333754 2000-11-30
WO 99/62768 PCT/US99/12110
accessible. The bag can be resealed by manually replacing and twisting the
ribbon about the
neck of the bag.
U.S. Patent No. 5,600,938 discloses apparatus for sealing a plurality of
spaced spots
across the flattened open end of a filled plastic bag. The bag is moved along
a conveyor past
a sealing mechanism where a plurality of spaced spots are welded or fused
across the open
end of the bag. In one embodiment a sealing mechanism includes a plurality of
heated pins
which penetrate the two layers of the open end of the bag while the end of the
bag is
substantially flat. These pins then move along with the bag in synchronism
with the conveyor
while the fusing occurs. In another embodiment, the sealing is accomplished by
using a wheel
having heated pins around its periphery and the wheel is rotated so that its
tangential speed is
in synchronism with the conveyor to successively make spaced fused spots
across the
generally flat open end of the bag. The apparatus seals a plurality of spaced
spots to only
delicately seal the bag to show evidence of tampering by breaking the seal but
allow the bag
to be opened without tearing or destroying the bag.
U. S. Patent No. 5,741,075 describes a package comprising a flexible plastic
bag and
a label, the bag having a closed end, the closed end being openable to provide
an opening for
access to the contents of the package, wherein, the closed end of the package
is initially sealed
at a sealing area and, wherein, the sealing area is provided with a line of
perforations to defme
the opening and reclosable by means of the label. The label is disclosed as
having on one face
two areas of adhesive separated by a non-adhesive area extending across
substantially the
whole width of the label, the adhesive areas being adapted to adhere to the
package, one to
each side of the line of perforations. A satisfactory method and apparatus for
forming the seal
and the line of perforations to provide an initial tamper-evident tear-off
strip is not disclosed.
Heretofore, no system has been devised for forming a reclosable tamper-proof
seal
which can be economically applied for safe-guarding the contents of the bag
prior to its being
opened by the ultimate consumer.
SUMMARY OF INVENTION
The apparatus disclosed herein is used to form a tamper resistant seal on
plastic bags
wherein the sides of the bag are welded together for forming a seal adjacent a
row of
perforations formed in the bag to facilitate tearing the seal from the bag to
gain access to the
2
CA 02333754 2007-01-05
contents. After the seal and perforated strip have been formed on the bag the
neck of the bag is
gathered and tied by twisting a wire-like ribbon about the neck of the bag.
The apparatus for forming the tamper resistant seal is preferably mounted on a
bag tyer, for example
of the type disclosed in U. S. Patent No. 5,483,134. Gathering belts arc
mounted on pulleys synchronized
with the gathering belts in the bag neck tying device.
The bag neck is flattened adjacent the gathering belts and the flattened bag
neck moves adjacent a
roller which has projections for forming a row of perforations in the neck of
the bag. The bag moves between
a pair of manifolds through which heated air flows to impinge against upper
and lower surfaces of the bag
neck for sealing the bag. The manifolds do not contact the surface of the bag
such that the bag neck can be
sealed even though printing ink on the surface of the bag may not have dried
or cured or if the heat softens the
ink.
Once the seal and row of perforations have been formed on the bag, the neck of
the bag moves
through the tying device where the neck of the bag is gathered, tied and
ejected from the tying device in
conventional manner.
It should be readily appreciated that in lieu of a twisted wire tie around the
gathered neck, other
closure means such as plastic wireless twist ties, plastic clips having a slot
or adhesive tape may be attached
to the gathered neck of the bag. The closure seals the bag between the row of
perforations and the contents to
prevent contamination and for maintaining freshness of the contents of the
bag.
In a further aspect, the present invention provides a method of forming a
tamper evident seal on a
plastic bag containing a loaf of bread comprising the steps of: flattening a
portion of the neck of the bag
adjacent the open end of the bag; positioning a segment of the flattened
portion to bridge between spaced
grippers; forming a row of perforations in the bag neck; directing heated air
jets to engage the segment of the
bag bridging between the spaced grippers for fusing panels of the bag together
to form a sealed strip spaced
from the row of perforations in the bag neck to facilitate removal of the
sealed strip from the bag, wherein the
row of perforations in the bag neck is formed before the heated air jets
engage the neck of the bag to assure
that the bag is perforated while it is cool and before it is heated to the
point at which it might tend to stretch
and deform while perforations are being formed, and wherein the air impinges
against the portion of the bag
bridging between the spaced grippers such that molten plastic or any ink which
may be softened by the heated
air is not offset onto the grippers or any other mechanism before the neck of
the bag is cooled; gathering the
flattened portion of the bag between the sealed segment and the loaf of bread;
and attaching a reusable closure
to said neck.
In a still further aspect, the present invention provides a method of forming
a tamper evident seal on
a plastic bag having a neck, with ink on the neck of the bag that may be
softened by heat, and sides welded
together to render the contents of the bag accessible containing a loaf of
bread comprising the
3
CA 02333754 2007-01-05
steps of: flattening a portion of the neck of the bag adjacent the open end of
the bag; positioning a segment of
the flattened portion of the neck of the bag such that it bridges space
between horizontally spaced grippers;
heating the portion of the neck of the bag that it bridges space between
spaced grippers to a temperature
sufficient for bonding material forming the neck of the bag for forming a
sealed segment such that the
contents of the bag are not accessible; gathering the flattened portion of the
bag between the sealed segment
and the loaf of bread; and attaching a reusable closure to said neck, wherein
the step of heating the flattened
portion of the bag comprises the steps of: delivering air heated to a
temperature in a range between about
315 and 600 Fahrenheit in a stream to impinge against the surface of the
bag; and gripping portions of the
bag adjacent opposite sides of the segment of the bag against which the stream
of air impinges, and wherein
the air impinges against the portion of the bag bridging between the spaced
grippers such that molten plastic
or any ink which may be softened by the heated air is not offset onto the
grippers before the neck of the bag is
cooled.
In a further aspect, the present invention provides a method for forming a
tamper evident closure on
a plastic bag containing a product said bag having an open end forming a neck
extending beyond a product in
a bag comprising the steps of: forming a row of perforations across the neck
of the bag between the product in
the bag and the open end of the bag neck; gripping the bag at spaced positions
adjacent opposite sides of the
row of perforations; and directing temperature controlled air to impinge
against the bag between the gripped
positions for forming a sealed strip between the row of perforations and the
open end of the bag, wherein the
air impinges against the portion of the bag bridging between the spaced
gripped portions such that molten
plastic which may be softened by the heated air is not offset onto the
grippers before the neck of the bag is
cooled.
In a still further aspect, the present invention provides an apparatus for
forming a tamper evident
closure on a plastic bag containing a product comprising: means for gripping
spaced portions of the bag;
means for forming a row of perforations in the bag adjacent the gripped
portions of the bag; and means for
delivering temperature controlled gas to impinge against the surfaces of the
bag between the gripped portions
for fusing portions of the bag between the gripped portions for forming a
sealed strip, said perforations being
positioned to permit removal of the sealed strip, said means for forming a row
of perforations in the bag and
said means for delivering temperature controlled gas to impinge against the
surfaces of the bag being spaced
apart such that the air impinges against the portion of the bag bridging
between the spaced gripped portions
such that molten plastic softened by the heated air is not offset onto the
means for gripping spaced portions of
the bag before the sealed strip is cooled.
In a further aspect, the present invention provides an apparatus for forming a
tamper resistant
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CA 02333754 2006-09-20
closure on a plastic bag containing a product comprising: a conveyor for
moving a plastic bag containing a
product along a path, said bag having an open end forming a neck extending
beyond the product in the bag;
an air nozzle for flattening the open neck as the bag is moved by said
conveyor; a pair of upper brushes and a
pair of lower brushes, a first of said pair of upper and lower brushes having
bristles arranged to engage the
flattened neck of the bag and draw the bag transversely across said conveyor,
second upper and lower hrushes
having angularly inclined bristles for moving the leading edge of the bag neck
longitudinally of the conveyor
while the trailing edge of the bag neck is engaged by the first upper and
lower brushes; a pair of upper belts
and a pair of lower belts, said upper and lower belts being horizontally
spaced apart such that one of said
upper belts and one of said lower belts engage opposite sides of a portion of
the neck of the ba- and one of
said upper belts and one of said lower belts engage a second portion of said
bag neck such that a portion of
the bag neck bridges space between the upper pair of belts and the lower pair
of belts; a pertorator wheel
adjacent one side of said bag neck and an anvil having a slot formed therein
adjacent the other side of the ba-
neck, said perforator wheel forming a row of perforations in the neck of the
bag moved by said upper and
lower belts; and upper and lower air dispensers positioned to deliver heated
air to impinge against upper and
lower surfaces of the portion of the bag neck bridging between the belts for
melting and forming a sealed strip
across the entire width of the bag neck for forming a seal extending generally
parallel to the row of'
perforations formed in the bag neck.
In a still further aspect, the present invention provides an apparatus for
forming a tamper evident
closure on a plastic bag containing a product comprising: a conveyor for
moving a plastic bag containing a
product along a path, said bag having an open end forming a neck extending
beyond the product in the bag;
means for flattening the open neck as the bag is moved by said conveyor; a
pair of upper belts and a pair of
lower belts, said upper and lower belts being horizontally spaced apart such
that one of said upper belts and
one of said lower belts engage opposite sides of a portion of the neck of the
bag and one of said upper belts
and one of said lower belts engages a second portion of said bag neck such
that a portion of the bag neck
bridges space between the upper pair of belts and space between the lower pair
of belts; a perforator wheel
adjacent one side of said bag neck and an anvil having a slot formed therein
adjacent the other side of the bag
neck, said perforator wheel forming a row of perforations in the neck of the
bag moved by said upper and
lower belts; an upper manifold positioned above the neck of the bag and a
lower manifold positioned below
the neck of the bag, said manifolds being positioned to deliver heated air to
impinge against upper and lower
surfaces of the portion of the bag neck bridging between the belts for melting
and forming a sealed strip
adjacent a row of perforations, said seal strip being a seal that can be torn
from the bag along the row of
perforations; and a diverter valve adjacent each of said upper and
3b
CA 02333754 2006-09-20
lower manifolds, each said diverter; valve being actuatable to divert air flow
from said upper and lower
manifolds and to exhaust the diverted air, without interruption of the flow of
air into the divei-ter valves.
In a further aspect, the present invention provides an apparatus for forming a
tamper evident closure
on a plastic bag containing a product comprising: gripper means for gi-ipping
spaced portions of'the hag neck
on an open end of a bag such that the neck bridges between the gripper means;
an upper manifold positioned
above the neck of the bag and a lower manifold positioned below the neck of
the bag, said nianif'olds bein-
positioned to deliver heated air to impinge against upper and lower surfaces
of the portion of the hag neck
bridging between the gripper means for melting and forming a sealed strip,
said sealed strip being a seal that
makes it evident if the bag has been opened; a diverter valve communicating
with each of said upper and
lower manifolds, each said diverter valve being actuatable to divert air flow
from said uppei- and lowei-
manifolds and to exhaust the diverted air, without interruption of the flow of
air into the diverter valves.
20
30
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CA 02333754 2000-11-30
WO 99/62768 PCT/US99/12110
DESCRIPTION OF THE DRAWINGS
Drawings of a preferred embodiment of the invention are annexed hereto, so
that the
invention may be better and more fully understood, in which:
Figure 1 is a perspective view illustrating the front of a bag neck tying
device having
apparatus for fonning a tamper resistant seal mounted thereon;
Figure 2 is an elevational view of the rear of the bag tying device and the
apparatus for
forming a tamper resistant seal;
Figure 3 is a fragmentary enlarged perspective view showing bag neck gathering
belts
and toothed rollers for fonming perforations;
Figure 4 is an enlarged fragmentary view illustrating rollers for perforating
the bag;
Figure 5 is a perspective view illustrating the rear and side of the apparatus
for forming
a tamper resistant seal;
Figure 6 is a perspective view of the apparatus for fomiing a tamper resistant
seal, the
cover being removed to more clearly illustrate details of construction;
Figure 7 is an enlarged elevational view showing the relationship of heaters,
air
manifolds and perforating rollers for forming a tamper resistant seal;
Figure 8 is an exploded perspective view illustrating parts of the apparatus
for fonning
a tamper resistant seal;
Figure 9 is a fragmentary diagrammatic view of a sealed strip and a row of
perforations
fonned on the neck of a bag;
Figure 10 is a perspective view of a bag showing the relationship of the seal
strip, row
of perforations and removable closure;
Figure 11 is a table showing examples of relationships of conveyor speed, bag
thickness and temperature; and
Figure 12 is a perspective view of the belt assembly in an operative position;
Figure 13 is a view similar to Figure 12 with the lower drive belt chassis in
a lowered
position;
Figure 14 is a diagrammatic view with the belts in the position illustrated in
Figure 12;
Figure 15 is a diagrammatic view with the belt assemblies in the position
illustrated in
Figure 13;
Figure 16 is a diagrammatic view of the heater and manifold assemblies with
the belt
assemblies in the position of Figure 12 and 14;
4
CA 02333754 2006-09-20
Figure 17 is a diagrammatic view similar to Figure 16 with the belt assemblies
in the position of
Figures 13 and 15;
Figure 18 is a diagrammatic side elevational view; and
Figure 19 is a diagrammatic view taken substantially along lines 19-19 of
Figure 18.
Numeral references are employed to designate like parts throughout the various
figures of the
drawing.
DESCRIPTION OF A PREFERRED EMBODIMENT
The wire tying device, generally designated by the numeral 10 in Figures 1 and
2 of the drawing is
mounted adjacent a side of conveyor 300 of the type disclosed in Burford U.S.
Patent No. 3,138,904 and
Burford U.S. Patent No. 3,919,829. Conveyer 300 carries, for example, loaves
125a, 125b and 125c of bread
to, through and out of wire tying device 10 in rapid succession. Conveyor 300
is well known to a person
skilled in the art and further description is not deemed necessary except in
conjunction with the drive
mechanism as will be hereinafter more fully explained. It should be
appreciated that othei- and fui-thei-
structures may form the conveyor.
Loaf 125c of bread is moving toward bag tying device lf) and the neck nlthc
iti
adjacent apparatus 100 for forming a tamper resistant closure on the nec.k of
the bag. 1_:aaf 12% has hee~1
moved by conveyor 300 and the gathering belts to a position where a wire-like
rihhon i; ~lro,::.i th(.1
gathered neck of the bag and twisted. Loaf 125a of bread has moved through
tyin(,y device 10 and has moved
out of the tying device. Referring to Figures 9 and 10 of the drawing,
apparatus 100 welds the sides I 25x and
125y of bag 125 together to form a tamper resistant seal strip 130. A row 1 32
of perforations is formed in the
neck of the bag 125 adjacent seal strip 130 to facilitate removing seal strip
130 froiri the hag to render the
contents ofthe bag accessible.
Twisted wire-like ribbon 115 closes the bag between perforated strip 132 and
the contents of h~w
125.
As best illustrated in Figures 9 and 10 of the drawing, opposite sides I 25x
and 125v of the hag 125
are welded together along seal strip 130 and a row 132 of perforations is
formed adjacent seal sti-ip 130. Aftei-
the tamper resistant seal 130, 132 has been formed on the neck of the bag 125;
any conventional i-emovable
closure such as a twisted wire-like tie 115, a
5
CA 02333754 2006-09-20
plastic clip having a slot that grips the neck of the bag or an adhesive tape
may be attached to the neck of the
bag for maintaining freshness and to prevent contamination of the contents of
the bag. Seal strip 130 can be
easily removed by tearing the bag along the row 132 of perforations.
It should be readily apparent that seal strip 130 forms a tamper evident
closure for bag 125 and that
the contents of the bag are not accessible until seal strip 130 is removed by
tearing the bag along row 132 of
perforations. Twist tie 115 can then be removed for opening the bag and
reattached for resealing the bag.
The apparatus 100 for forming a tamper resistant closure includes a pair of
rollers for engaging
opposite sides of the neck of the bag for forming row 132 of perforations and
a pair of manifolds for directinQ
a heated gas, such as air, to impinge against surfaces of the bag neck
adjacent the row 132 of perforations for
welding panels of the bag neck together to form the seal strip 130.
Referring to Figures 3, 4 and 8 of the drawing, the numeral 140p generally
refers to a roller having
teeth formed by the periphery thereof while a roller 150p has a groove formed
therein for receiving teeth on
roller 140p. As the neck of a bag moves between rollers 140p and 150p the
teeth on roller 140p perforate the
neck of the bag and form row 132 of perforations in the neck of the bag.
As best illustrated in Figures 2 and 8 of the drawing, a pair of gathering
belts 41 and 43 extend
around driven rollers 140 and 144 and around a drive roller 145 mounted on
shaft. 146. Shaft 146 has a pulley
147 mounted on the opposite end thereof and is driven by a belt 25a extending
around pulleys 147 and 148.
Pulley 148 is mounted on a shaft 25 which drives the upper gathering belt 29
routed around driven pulley and
idler pulleys 26 and 27 of the bag neck tying apparatus 10.
Roller 150p has a groove formed in the surface thereof and is driven by a pair
of gathering belts 51
and 53 extending around rollers 150, 154 and 155, as illustrated in Figure 8.
Drive roller 155 is mounted on
shaft 156 which has a pulley 157 mounted on the end thereof. A drive belt 35a
extends around pulley 158
mounted on the end of shaft 35 which drives the lower gathering belt 39 of
tyer 10 which extends around
driven pulley and pulley 36 of the bag tying apparatus 10.
It should be noted that upper gathering belts 41 and 43 and lower gathering
belts 51 and 53
grippingly engage the neck of the bag adjacent opposite sides of the segment
of the
6
CA 02333754 2006-09-20
bag that is to be sealed to form sealed strip 130. Teeth on roller 140p are
preferably spaced from but adjacent
the segment of the neck of the bag between the gathering belts 41 and 43.
It should be readily apparent that roller 140p having teeth formed thereon is
driven in synchronized
relation with gathering belt 29 through the belt 25a extending around pulleys
147 and 148 and that roller 150p
having a groove formed therein is driven in synchronized relation to the lower
gathering belt by the drive belt
35a extending around pulleys 157 and 158.
Rollers 140, 144 and 145 are mounted on a mounting plate 149 and rollers 150,
154 and 155 are
mounted on a mounting plate 159. The opposite ends of shafts 146 and 156 are
supported by mounting plates
149a and 159a.
A top plate 149b has opposite ends secured by screws between mounting plates
149 and 149a and a
side plate 149c extends vertically between mounting plates 149 and 149a and
generally perpendicular to top
plate 149b.
An upper heater 160 is secured by U-bolts 162 and 164 to top plate 149b, as
best illustrated in
Figures 6 and 7 of the drawings. The rear end of the upper heater 160 extends
through passage 160a formed
in mounting plate 149a.
A lower heater 170 extends through openings formed in mounting plates 159 and
159a and is
secured by U-bolts 172 and 174 to a bottom mounting plate 159b adjacent a
vertically extending mounting
plate 159c.
Heated air is delivered from heater 160 into an upper manifold 165 and heated
air is delivered from
heater 170 into a lower manifold 175.
Manifolds 165 and 175 preferably have elongated orifices formed therein which
form a row of jets
of air which are projected to impinge against the surface of the neck of a bag
moving between manifolds 165
and 175. The temperature and volume of air is selected to deliver sufficient
heat for fusing panels of the bag
together to form seal strip 130.
It should be appreciated that the projection of jets of heated air to impinge
against the surface of the
bag allows panels of the bag to be fused without physically contacting
surfaces of the bag with heated sealing
elements. Thus, even though the neck of the bag may carry wet ink which has
not cured, or ink softened bv
the heat, seal strip 130 can be formed thereon. Wet or softened ink will not
offset onto manifolds 165 and 175
because the manifolds do not physically engage surfaces of the neck of the
bag.
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WO 99/62768 PCT/US99/12110
Air manifolds 165 and 175 preferably have for example twenty orifices about
0.040
inches arranged to form outlet openings which project air streams to impinge
against panels
125x and 125y above and below the neck 125 of each bag for heating panels 125x
and 125y
to a temperature sufficient for fusing panels 125x and 125y together to form
the seal strip
130.
Heaters 160 and 170 preferably electrically heat air flowing therethrough
delivered
from an air supply line 180 through a pressure regulator 182, filter 184 and
feed line 185, as
illustrated in Figure 2 of the drawing. Air feed line 185 preferably passes
through a control
valve 186 for controlling the pressure and volume of air delivered through
line 187 to heaters
160 and 170. The heater mount for the lower 170 is substantially a mirror
image of the heater
mount for heater 160 and heaters 160 and 170 are mounted on a frame to permit
separation of
rollers 140 and 150 in the event that a heel on a loaf of bread in bag 125
falls down into the
nip between rollers 140 and 150. Roller 140 is spring urged downwardly toward
roller 150
but can pivot upwardly if necessary to allow a heel or other obstruction to
pass through the
nip between rollers 140 and 150.
Each heater 160 and 170 is preferably provided with an electric heating
element
connected through a thermostat which is adjustable for controlling the
temperature of air
delivered from heaters 160 and 170 to manifolds 165 and 175. Further,
thermocouples are
mxmted in manifolds 165 and 175 to indicate the temperature of air supplied by
heaters 160
and 170 for assuring that the temperature is maintained in a predetermined
range.
As shown in the table of Figure 11, the air temperature required for forming
seal strip
130 varies depending upon the thickness and composition of the material used
for forming
bag 125 and the speed of conveyor 300 moving the neck of the bag between
manifolds 165
and 175. As the thickness of the bag increases the temperature of air
delivered through air
manifolds 165 and 175 generally increases. As the speed of the conveyor
increases the
temperature of the air is increased to deliver a controlled volume of air and
heat through
manifolds 165 and 175 for forming seal strip 130.
Air supplied through pressure regulator 182 is preferably about 25psi and
heaters 160
and 170 are preferably selected to heat the volume of air flowing through
manifolds 165 and
175 to a maximum temperature of for example 600 Fahrenheit. The
thermocouples provide
a read out of temperature of air flowing through manifolds 165 and 175 and the
temperature
8
CA 02333754 2006-09-20
of air delivered through the heaters 160 and 170 is adjustable to provide the
desired quantity of heat for
forming seal strip 130.
The wire tying device, generally designated by the numeral 10 in Figures I and
2 of the drawinu.
forms no part of the invention claimed herein except in combination with the
appai-atus for forniinL, a tanlpcr
resistant closure. The wire tying device generally comprises upper and lower
gathering belts 29 and 39, the
upper gathering belt 29 being driven by a pulley on a shaft 25 and the lower
gathering belt 39 being driven by
a pulley on a shaft. 35, as described in U.S. Patent No. 5,483,134. As noted
above, movement of i-ollers in the
apparatus for forming a tamper resistant closure are synchronized with the
rotation of shafts 25 and 35
through belts 25a and 35a.
The upper and lower gathering belts 29 and 39 move bags 125 along a path to a
position adjacent a
needle assembly, a twister hook assembly and a holder-shear assembly (not
shown) foi- wrapping a wire-like
tie around a gathered neck of the bag 125.
Terms such as "horizontal," "vertical," "up," and "down" when used in refei-
ence to the drawin~p,
generally refer to the orientation of the parts in the illustrated embodiment
and not necessarily in the
described orientation during use.
SECOND EMBODIMENT
A second embodiment of the apparatus for forming a tamper resistant closure on
the neck of a bag is
illustrated in Figures 12 through 19. The parts of the apparatus are
substantially the same as that of the first
embodiment except that certain parts and operations have been rearranged.
Referring to Figures 16 and 18, a heater housing 200 has partition wal ls 202
and 204 mounted
between end walls for forming a hot zone 201, and intermediate zone 203 and a
cool zone 205 in the heater
housing 200. An air filter is mounted in the intermediate zone 203 for
cleaning air drawn through the
intermediate zone by a blower 230 in the cool zone 205 for delivering air to
heaters 260 and 270. Exhaust
fans 208 are mounted in the hot zone 201 for exhausting spent air from heater
housing 200, as will be
hereinafter more fully explained.
Referring to Figures 12 and 18 of the drawing, outboard upper gathering belt
241 and inboard upper
gathering belt 243 are mounted on an upper chassis 222 and outboard lower
gathering belt 251 anci inhmuci
lower gathering belt 253 are mounted on a lower chassis 225.
9
CA 02333754 2006-09-20
The lower chassis 225, carrying belts 251 and 253 is movable fi-om the
position illustrated in I iuw-c
12 to the position illustrated in Figure 13, if capacitive sensor 215, best
illustrated in Figure 14, detects a heel
or other obstruction has fallen into the neck of the bag. After the heel or
other obstruction has been i-emoved.
the system is reset and the lower chassis 225 moves back to the position
illustrated in Figure 12.
The outboard upper gathering belt 241 extends around outer timing belt pulleys
240, 244, 245 and
246. The inboard upper gathering belt 243 extends around pulleys 240a, 244a,
245a and 246a Pulleys 240 and
240a are mounted on a shaft 240b, pulleys 244 and 244a are mounted on a shaft
244b, pulleys 245 and 245a
are mounted on a shaft 245b and pulleys 246 and 246a are mounted on a shaft
246b.
As best illustrated in Figure 18, the upper chassis 222 is formed by spaced
plates 223 bolted or
otherwise secured between end walls. In the illustrated embodiment the upper
chassis is not movable and
shafts 240b-246b are supported in bearings 227 mounted in the spaced plates
223.
The outboard lower gathering belt 251 extends around outer pulleys 250, 254,
255 and 256. The
inboard lower gathering belt 253 extends around pulleys 250a, 254a, 255a and
256a. Pulleys 250 and 250a are
mounted on a shaft 250b, pulleys 254 and 254a are mounted on a shaft 254b,
pulleys 255 and 255a are
mounted on a shaft 255b and pulleys 256 and 256a are mounted on a shaft 256b.
The lower chassis 225 is
formed by spaced plates 224 and 226 bolted or otherwise secured between slide
plates which move vertically
relative to the end walls. In the illustrated embodiment the lower chassis is
movable and shafts 250b-?56h are
supported in bearings 228 mounted in the spaced plates 224 and 226. As will be
hereinafter more fully
explained, the bearings 227 and 228 are spaced inwardly from the timing
pulleys 240 - 25611 and manit'olds
265 and 275 a distance sufficient to prevent excessive heating of the bearings
227 and 228 by spent air drawn
vertically through the hot zone 201 in heater housing 200 by exhaust fans 208.
The perforator wheel 220 is driven by a belt 240x which extends around a hub
on the perforator
wheel and is driven by a pulley (not shown) on shaft 255b.
An air nozzle, illustrated in Figure 14, is connected to a flexible tube
through which air is delivered
from an air compressor (not shown) or other suitable source of compressed air
to form a jet which flattens the
neck of the bag and positions it to enter the nip between a first pair of
brushes 210 and 214 positioned above
the edge of the conveyor and a
35
CA 02333754 2006-09-20
second pair of brushes 212 and 216 positioned below the edge of the conveyor.
The air jet pushes side 125x
of bag 125 toward side 125y of bag 125.
A capacitive sensor 215 is positioned between the air nozzle 209 and brushes
210-216 for sensing
whey a heel of a loaf of bread has fallen down into the neck of the bag. If a
heel or other obstruction has
fallen down into the neck of the bag, the sensor sends a signal to stop the
conveyor and actuate the sealing
apparatus to the non-operable position, as shown in Figures 13, 15 and 17. The
sensor 215 is a capacitoi- type
sensor which senses a change in mass adjacent the sensor out of a
predetermined range.
If the bag neck is unobstructed, the neck of the bag moves between upper and
lower paii-s of brushes.
First upper and lower brushes 210 and 212, best illustrated in Figure 14, have
stiff bristles and rotate in
opposite directions such that the lower surface of the upper brush 210 and the
upper surface of the lower
brush 212 move in the same direction and engage the neck of the bag to draw
the bag laterally across the
conveyor until the contents of the bag engage guide bars which limit lateral
movement of the ba- when the
contents of the bag move to engage the guide bars. The sweeping action of the
first upper and lower brushes
210 and 212 draws the bag taut around the contents of the bag.
The second upper and lower brushes 214 and 216 have spaced rows of angular bi-
istles %ahich arc
slightly longer than the bristles of the first upper and lower brushes 210 and
212 for moving the leading edge
of the neck of the bag away from the trailing edge to flatten the neck of the
bag and t4 evacuate air froni the
bag before it is sealed. The angularly disposed bristles are preferably about
1/8 inch larger in diameter than
the bristles on the first upper and lower brushes 210 and 212.
It should be readily apparent that the first pair of upper and lower brushes
210 and 212 draw the bag
around the product while the second pair of upper and lower brushes 214 and
216 flatten the ba u neck.
evacuate air from the inside of the bag and position the leading edge of the
bag neck between upper belts 241
and 243 and lower belts 251 and 253. The fast set of brushes 210 and 212 which
move the neck of the hag,
laterally across the conveyor tend to resiliently hold and resist movement of
the neck of the bag longitudinally
of the conveyor by the second pair of upper and lower brushes 214 and 216 and
the gathering belts. Thus the
leading edge of the neck of the bag is gripped by the gathering belts and the
trailing edge is pulled from
between the brushes so that the neck of the bag is smoothed as it is drawn.
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between the gathering belts and the portion of the neck of the bag that
bridges the space
between horizontally spaced belts 241 and 243 is substantially planar.
As illustrated in Figure 14 and 15, the perforating assembly is fornmed by a
perforator
wheel 220 having teeth 221 spaced around its periphery positioned below the
neck of the bag
and an anvil 218 having a slot 217 formed therein above the neck of the bag.
The neck of the
bag is held taut between lower surfaces of belts 241 and 243 and upper
surfaces of belts 251
and 253.
Each tooth 221 on the perforator wheel 220 is shaped to make a defined cut or
elongated slot in the portion of the bag neck bridging between the belts. An
area 221a of
defined length is formed between adjacent teeth 221 on the perforator wheel
220 to leave
spaced areas on the neck of the bag which are not cut. The perforator wheel
220 is driven by
a pair of -belts in synchronized relation with the belts moving the bag so
that every bag
moving adjacent the perforator wheel is substantially identical.
The perforator wheel 220 is mounted on a stub shaft secured in a bearing to
the lower
belt chassis 225. Teeth on the perforator wheel extend into the slot on the
lower surface of
the anvil carried by the upper chassis 222 such that the bag is supported by
flat surfaces
adjacent opposite sides of the perforator wheel.
Refen-ing to Figure 12 of the drawing, upper gathering belts 241 and 243 are
mounted
on an upper chassis 222 and lower gathering belts 251 and 253 are mounted on a
lower
chassis 225, as herein before described. The lower chassis 225, canrying belts
251 and 253 is
movable from the position illustrated in Figure 12 to the position illustrated
in Figure 13, if
capacitive sensor 215 detects a heel which has fallen into the neck of the
bag. After the heel
or other obstruction has been removed the system is reset and the bottom
chassis moves back
to the position illustrated in Figure 12. The perforator wheel 220 is driven
by a belt 240x
which extends around a hub on the perforator wheel and is driven by a pulley
(not shown) on
shaft 255b.
Refen-ing to Figures 18 and 19 of the drawing, shaft 240b which carries
pulleys 240
and 240a and shaft 255b having pulleys 255 and 255a mounted thereon, are
driven by a belt
320 routed around pulleys as illustrated in Figure 19 of the drawing. The
upper pulley 302 is
mounted on the end of shaft 246b. Shaft 245b is an idler shaft and does not
have a pulley
mounted on the rear end thereof.
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A pulley 304 is mounted on shaft 255b for driving timing belt pulleys 254 and
254a.
Pulley 305 is mounted on shaft 256b for driving tinming belt pulleys 350 and
350a. Idler
pulley 306 is mounted on a stub shaft carried by the lower chassis 225.
A direct current driven motor 315 is electrically connected to a suitable
driver, such as
the output from the tyer or a decoder module on the conveyor for driving belts
241, 243, 251
and 253 at a speed equal to the surface speed of the conveyor 300. Motor 315
has a drive
pulley 310 mounted on the drive shaft for driving belt 320 which extends
around an idler
pulley 309, pulley 302 for driving upper belts 341 and 343, around drive
pulley 304, idler
pulley 305 and drive pulley 306 for driving shafts 246b and 256b, and around
pulley 308.
The upper chassis 222 carrying the upper belts 241 and 243 is stationary. The
lower
chassis 225, carrying belts 251 and 253 can be moved vertically, as
illustrated in Figure 19,
for moving the lower chassis 225 to an off position for separating the upper
and lower pairs
of belts. Referring to Figure 19, it should be readily apparent that when
chassis 225 moves
downwardly, the length of drive belt 320 is unchanged since pulleys 304, 305
and 306 rotate
and advance along belt 320 as chassis 225 moves vertically. Thus, the belt
tension is not
changed.
Referring to Figure 16 of the drawing, a three-stage blower 230 delivers a
high volume
of pressurized air to electric heaters 260 and 270. Heaters 260 and 270 are
preferably
configured to circulate the air over heating elements for heating the air to a
controlled
temperature and delivering the air through diverter valves 262 and 272,
respectively, to upper
manifold 265 and lower manifold 275. Each manifold 265 and 275 has an
elongated slot
through which heated air is delivered to impinge against the flattened surface
of the neck of
the bag bridging space between outboard belts 241 and 251 and inboard belts
243 and 253.
It should be appreciated that the perforator wheel 220 has already formed row
132 of
perforations in the neck of the bag before the neck of the bag moves between
upper and lower
manifolds 265 and 275. This assures that the bag is perforated while it is
cool and before it is
heated to the point at which it might tend to stretch and deform when teeth
221 on the
perforator whee1220 engage the neck of the bag. The heated air, flowing at a
high velocity,
impinges against upper and lower surfaces of the neck of the bag for welding
the upper and
lower surfaces together. It should be appreciated that air impinges against
the portion of the
bag bridged between the belts such that the molten plastic or any ink which
may be softened
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by the hot air is not offset onto the belts or any other mechanism before the
neck of the bag is
cooled.
Upper and lower diverter valves 262 and 272 are provided with spring-loaded
paddles
which are rotated by air cylinders from the position illustrated in Figure 16
to the position
illustratsd in Figure 17 when the lower chassis 225 is actuated to an
inoperable position. This
causes the heated air to be diverted away through exhaust ports from the neck
of any bag
which might be positioned adjacent the manifolds 265 and 275 when the lower
chassis 225 is
actuated downwardly. Diverting the air, as illustrated in Figure 17 also
directs the air away
from the vicinity of the belts to assure that the belts are not overheated.
As best illustrated in Figure 16, the three stage blower 230 has an intake
line 230a
extending through partition wall 204 for drawing air from the intermediate
zone 203 through
air filter 206. Air is discharged by blower 230 through lines 260a and 270a
into heaters 260
and 270. Air preferably is delivered along a plurality of paths through
heaters 260 and 270 to
diverter valves 262 and 272. When the spring-loaded paddles are in the
position illustrated in
Figure 16, air is delivered through manifolds 265 and 275 to impinge against
the upper and
lower surfaces of the neck of the bag bridging between the inboard and
outboard belts. When
levers 262a and 272a are rotated, the spring-loaded paddles are moved from the
position
illustrated in Figure 16 to the position illustrated in Figure 17 for
delivering air through
exhaust ports 262e and 272e into the hot zone 201 and the air is evacuated
from the hot zone
201 by exhaust fans 208 mounted at upper and lower ends of the hot zone 201.
Diverter valves 262 and 272 positioned immediately adjacent manifolds 265 and
275
allows the air to be diverted quickly from the manifolds to the exhaust ports
and back to the
manifolds. Since heated air flows continuously through diverter valves 265 and
275, the
mechanism does not deviate in temperature and does not require warm-up periods
when the
paddle is moved from one position to the other.
The provision of an intermediate zone 203 between the hot zone 201 and the
cool zone
205 effectively isolates the hot zone 201 from the cool zone 205 where the
electrical controls
and blower 230 are located. Further, drawing air through filter 206 adjacent
partition wall
202 pre-heats air drawn into blower 230.
The three stage blower 230 is configured to deliver a high volume of
relatively high
pressure air through the heaters and manifolds 265 and 275. The continuous
regulated supply
of air through heaters 260 and 270 over heating elements assures that the air
temperature and
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volume is maintained within parameters to assure that bag necks will be sealed
as they move
between manifolds 265 and 275 while assuring that excessive heat is not
delivered. Heating
elements in heaters 260 and 270 are thermostatically controlled to
acconunodate bags
constructed of different materials and made of plastic of different
thicknesses.
It is important to note that brushes 210, 212, 214 and 216 are configured for
flattening
the neck of the bag and evacuating excess air from the inside of the bag so
that the row 132 of
perforation and seal strip 130 can be formed consistently on bag necks.
The belts are preferably timing belts which have teeth 241t undercut or
shortened to
permit edges of the belt to extend beyond flanges on the timing belt pulleys
240 - 256a
carrying the belts. This assures that the neck of the bag will not wrap around
and be pinched
between the belt and the flanges on the timing belt pulleys. A layer of soft
pliable material
241x is vulcanized onto the outer surface of each belt body 241y to provide a
relatively hard
durable surface which is in engagement with the timing belt pulleys and to
provide a relatively
soft pliable surface on each belt which engages the neck of the bag. This
causes the belts to
grip the bag to minimize slippage as the neck of the bag is moved adjacent the
perforator
wheel 220 and between upper and lower manifolds 265 and 275 where seal strip
130 is
formed.
Teflon reinforced slider plates 300s are secured to mounting plates 301 bolted
or
otherwise secured to the upper and lower chassis 222 and 225. Belts spanning
space between
pulleys 344 and 345 and between pulleys 354 and 355 engage slider plates 300s
which
prevent deflection of the belts to assure that the belts fu-mly grip spaced
portions of the bag
neck adjacent opposite sides of upper and lower manifolds 265 and 275.
As best illustrated in Figure 12 of the drawing, diverter valves 262 and 272
have levers
262a and 272a extending outwardly therefrom which are engaged by a turnbuckle
on the rod
of a cylinder for actuating spring loaded paddles in the diverter valves from
the position
illustrated in Figure 16 to the position illustrated in Figure 17.
While preferred embodiments of the method and apparatus for forming a tamper
resistant seal have been disclosed, it should be apparent that other and
further embodiments
may be devised without departing from the basic concepts of the invention.
