Note: Descriptions are shown in the official language in which they were submitted.
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FOLDING DEVICE AND BAG MAKING AND POSITIONING MACHINE
TECHNICAL FIELD
The present invention relates to a device to fold sheet material over
itself about a longitudinal fold line and to a machine for making and
positioning bags
formed of hot-melt plastic material so that the bags may be stuffed with
products.
BACKGROUND ART
Machines to make and position plastic bags so that the bags may be
stuffed with products are known and are used in bakeries where it is desired
to bag
perishable foodstuffs. It is desired that these machines operate at high
speeds to
reduce processing times and to handle the capacity of upstream and downstream
systems.
For example, Italian Patent Application No. V191A000086 discloses a
machine for making bags from a band of transparent hot-melt plastic material.
The
band of plastic material is intermittently advanced to a fusing and cutting
station
where individual bags are formed from the band of plastic material. The
individual
bags are then intermittently advanced to a filling station which includes a
rotatable
filling clamp. The filling clamp includes an angular support having an
inclined lower
surface and is actuable to move a product from a feeder belt into each bag. A
nozzle
discharges a jet of compressed air into each bag to inflate the bag to
facilitate insertion
of the product via the filling clamp.
Although this machine increases bagging capacity, several drawbacks
exist. In particular, when the filling clamp is actuated to move a product
from the
feeder belt and into a bag, the inclined lower surface of the filling clamp
may interfere
with the open edge of the bag. Also, when the advancement rate of the machine
is
increased, support for the individual bags decreases making it difficult to
support the
bags, which in turn results in bags lifting from the machine.
An alternative machine for making and positioning bags formed of hot-
melt plastic is disclosed in U.S. Patent No. 5,373,390 to Frigo et al. This
machine
includes a feeding station for feeding a band of pre-folded plastic material
to a bag
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forming station. The bag forming station fuses and cuts the band of plastic
material to
form individual plastic bags. The individual plastic bags are intermittently
advanced
to a filling unit by way of a vacuum belt. The filling unit includes a nozzle
to
discharge a jet of compressed air to inflate each bag as well as a clamp to
hold an edge
of each bag as the bag is inflated so that the bag may be stuffed. The clamp
is
adjustable to maintain each bag at the same angle as the product being
inserted into
the bag. Although the capacity of this machine is satisfactory, the feeding
station
supplies a pre-folded band of plastic material. Pre-folded plastic material of
this
nature is expensive making the overall bagging process uneconomical. Also, the
use
of a clamp to grasp the edge of each bag as the bag arnves at the filling unit
makes
timing critical and slows the bagging process. Accordingly, improved machines
for
making and positioning bags formed of hot-melt plastic are desired.
It is therefore an object of the present invention to provide a novel
folding device for folding sheet material over itself about a longitudinal
fold line to
define upper and lower flaps. It is also an object of the present invention to
provide a
novel machine for making and positioning bags formed of hot-melt plastic
material.
DISCLOSURE OF THE INVENTION
According to one aspect of the present invention there is provided a
2o folding device for folding sheet material over itself about a longitudinal
fold line to
define upper and lower flaps comprising:
a support;
a generally planar first folding element mounted on said support
behind which said sheet material passes, said first folding element presenting
a first
folding edge extending generally normal to the longitudinal axis of said sheet
material
over which a first portion of said sheet material is folded and a second
folding edge
extending at an angle to said first folding edge over which a second portion
of said
sheet material is folded, said first and second folding edges meeting at a
corner; and
a generally planar second folding element mounted on said support and
3o spaced from said first folding device and presenting a third folding edge
forming
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generally a right angle with said second folding edge over which said first
portion of
said sheet material is folded and over which said second portion of said sheet
material
passes.
In a preferred embodiment, the comer is laterally offset with respect to
the central longitudinal axis of the sheet material. It is also preferred that
the first
folding element is in the form of a trapezoidal plate. Preferably, the second
folding
element is pivotably mounted on a support bar on the support. In one
embodiment,
the second folding element is in the form of a triangular plate while in
another
embodiment, the second folding element is in the form of a rectangular bar.
According to another aspect of the present invention there is provided a
machine for making and positioning bags formed from a band of hot-melt plastic
material folded over itself about a longitudinal fold line and defining upper
and lower
flaps, said machine comprising:
a cutting mechanism receiving said band of plastic material as said
is band of material is intermittently advanced and forming cuts in a region of
said band
of plastic material at longitudinally spaced locations, said cuts extending
partially
across said band of plastic material in a transverse direction from a
peripheral edge of
said band of plastic material opposite said fold line;
a sealing mechanism sealing and cutting said band of plastic material at
longitudinally spaced locations in a transverse direction in line with said
cuts and
extending generally from said fold line to said cuts thereby to form
individual bags
each having an open end;
a nozzle downstream of said sealing mechanism discharging air to
inflate each individual bag prior to filling;
a conveyor to advance each individual bag from said sealing
mechanism to said nozzle; and
a retainer extending at least from said sealing mechanism to said
nozzle, said retainer engaging an upper surface of said band of plastic
material at said
region to hold said band of plastic material at said sealing mechanism and to
hold said
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individual bags on said conveyor as said individual bags are advanced by said
conveyor and inflated by air discharged via said nozzle.
According to yet another aspect of the present invention there is
provided a machine for making and positioning bags formed from a band of hot-
melt
plastic material folded over itself about a longitudinal fold line and
defining upper and
lower flaps, said lower flap projecting laterally beyond said upper flap, said
machine
comprising:
a cutting mechanism receiving said band of plastic material as said
band of material is intermittently advanced and cutting said lower flap in a
transverse
io direction at longitudinally spaced locations in a region generally
extending from a
peripheral edge of said upper flap to a peripheral edge of said lower flap;
a sealing mechanism sealing and cutting said band of plastic material
in a transverse direction extending generally from said fold line to the
peripheral edge
of said upper flap at longitudinally spaced locations and in line with cuts
formed in
15 said lower flap by said cutting mechanism thereby to form individual bags
each
having an open end;
a nozzle downstream of said sealing mechanism discharging air to
inflate each individual bag prior to filling;
a conveyor to advance each individual bag from said sealing
2o mechanism to said nozzle; and
a retainer extending at least from said sealing mechanism to said
nozzle, said retainer engaging an upper surface of said lower flap at said
region to
hold said band of plastic material at said sealing mechanism and said
individual bags
on said conveyor as said individual bags are advanced by said conveyor and
inflated
25 by air discharged via said nozzle.
The present invention provides advantages in that since the sheet
material is folded over itself about a longitudinal fold line by the folding
device, stock
sheet material can be used to feed bag making machines thereby reducing costs.
Also,
the retaining belt in the bag making machine provides a simple, elegant and
reliable
3o method of retaining the band of plastic material at the sealing station and
the
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individual bags on the conveyor belt as the conveyor belt moves and while the
individual bags are being inflated.
BRIEF DESCRIPTION OF THE DRAWING
Embodiments of the present invention will now be described more
fully with reference to the accompanying drawings in which:
Figure 1 is a schematic illustration of an article bagging machine;
Figure 2 is a schematic perspective view of a folding device and a bag
making and positioning machine forming part of the article bagging machine of
1o Figure 1;
Figure 2a is a perspective view of a gusset forming device forming part
of the bag making and positioning machine of Figure 2;
Figure 3 is a front perspective view, partly cut-away, of the folding
device of Figure 2;
15 Figure 4 is a rear perspective view of the folding device of Figure 2 in
an open condition;
Figures $a to 5c are perspective views, partly exploded, of the folding
device of Figure 3;
Figure 6 is a side elevational view of a sealing station forming part of
20 the bag making and positioning machine of Figure 2;
Figure 7 is an enlarged side elevational view of the sealing station of
Figure 6;
Figure 8 is a schematic side elevational view of a filling station
forming part of the article bagging machine of Figure 1;
25 Figure 9 is a schematic top plan view of the filling station of Figure 8
and the bag making and positioning machine of Figure 2;
Figures l0a to lOc are schematic perspective views of alternative
embodiments of conveyors used in the bag making and positioning machine of
Figure
2;
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Figures 11 a to 11 c are side elevational, rear elevational and top plan
views of a cradle used to load the folding device of Figure 3 with a roll of
sheet
material; and
Figure 12 is a perspective view of a sealing unit for the folding device
of Figure 3.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to Figure 1, an article bagging machine is shown and is
generally indicated to by reference numeral 10. Article bagging machine 10
includes
a folding device 12 to fold sheet hot-melt plastic material 13 over itself
about a
longitudinal fold line and form a band 14 of plastic material. The band of
plastic
material defines upper and lower flaps 14a and 14b respectively with lower
flap 14b
protruding laterally beyond upper flap 14a. Indicia may be pre-printed on the
sheet
plastic material. The band 14 of plastic material exiting from the folding
device 12 is
fed to a bag making and positioning machine 16 where the band of plastic
material is
partitioned into individual bags which are then stuffed with products to be
packaged
by way of a filling station 18. A programmable controller 20 communicates with
the
folding device 12, the bag making and positioning machine 16 and the filling
station
18 and synchronizes their operation so that the products are properly bagged
by the
2o article bagging machine 10.
Referring now to Figures 3 to S, the folding device 12 is better
illustrated. As can be seen, the folding device includes a housing 30 for
accommodating a roll 32 of the sheet plastic material 13. The roll is
supported on a
shaft 34. The ends of the shaft 34 are rotatably accommodated by supports 35
within
the housing 30. A shelf 36 within the housing is positioned above the roll 32
and
shaft 34. A drive roller 40 is supported by the shelf 36 adjacent one of its
ends around
which the sheet plastic material 13 is wound. The drive roller 40 is rotated
by a drive
(not shown) to unwind the sheet material 13 from the roll 32. A tension
controller
(not shown) maintains tension on the sheet material as it is unwound from the
roll 32
3o to control the movement of the sheet material.
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The shelf 36 is slideable along guides (not shown) within the housing
30 to expose the shaft 34, roll 32 and drive roller 40 when the housing 30 is
opened.
This facilitates replacement of the shaft 34 and roll 32 when the roll 32 of
sheet
material has been unwound as will be described.
The housing 30 has an opening in a side thereof through which the
sheet material passes. The housing also includes a generally planar, stepped
upper
surface 42. A pair of superimposed, spaced folding plates SO and 52 are
mounted on
the lower step of the upper surface. The lower folding plate SO is generally
trapezoidal and presents a pair of folding edges 54 and 56, one folding edge
54 of
which extends normal to the longitudinal axis of the sheet plastic material
and the
other folding edge 56 of which forms an angle with respect to the folding edge
54.
The folding edges 54 and 56 meet at a corner 58 that is laterally offset with
respect to
the central longitudinal axis of the sheet plastic material.
The upper folding plate 52 is generally triangular and is pivotally
mounted on a support bar 60 on the upper surface 42 so that it is spaced
slightly above
the lower folding plate 50. The upper folding plate 52 presents a folding edge
60
forming about a 90° angle with the folding edge 56. The pivotal
connection between
the support bar 60 and the upper folding plate 52 allows the lower folding
plate 50 to
be exposed to facilitate threading of the folding device 12 with the sheet
plastic
material.
Although not shown, a photodetector is positioned in the housing 30 to
detect the position of one edge of the sheet plastic material. Output from the
photodetector is fed back to an adjustment mechanism within the housing 30 to
move
the shaft 34 axially so that the edge of the film is properly positioned. In
this manner,
the position of the corner 58 with respect to the central longitudinal axis of
the sheet
plastic material can be controlled.
Refernng now to Figures 11 a to 11 c, a cradle 70 for transporting a roll
32 of the sheet plastic material when to the folding device 12 when the
folding device
needs to be restocked is shown. As can be seen, the cradle 70 includes a
wheeled
3o undercarriage 72 on which the roll of sheet material can be supported. Side
members
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74 extend upwardly from opposed sides of the undercarnage 72 and include
laterally
spaced uprights 76 spanned by a bridge 78. A pair of recess are formed in the
top of
each bridge 78 to accommodate the shaft 34. Lifting arms 80 are pivotally
mounted
on the side members. Each lifting arm 80 has a recess 82 formed therein at one
end to
accommodate the shaft. The other end of each lifting arm 80 is bent upwardly
and
outwardly. A handle 84 spans the other ends of the lifting arms to allow an
operator
to push the cradle 70 as well as push downwardly on the lifting arms 80 to
pivot the
lifting arms about the side members and lift the roll 32 of sheet plastic
material from
the undercarriage 72. In this manner, the roll of sheet material can be pushed
into the
housing 30 when the housing is opened and lifted into position on the supports
35.
The roll of sheet plastic material can then be taped to the sheet plastic
material of the
previous roll without requiring re-threading of the folding device 12. When
this is
being done the drive roller 40 is manually locked to inhibit its rotation and
thereby
facilitate the taping procedure.
The bag making and positioning machine 16 includes a plurality of
stations supported by a frame (not shown) at longitudinally spaced locations.
Specifically, at the upstream end of the machine 16 adjacent the folding
device 12 is a
feeding station 120 to feed the band of plastic material 14 emerging from the
folding
device 12. Feeding station 120 includes a first set of transverse rollers 122
to 128
2o around which the band of plastic material is wound. A drive roller 140
forms a nip
with roller 128 through which the band 14 of plastic material passes to draw
the band
of plastic material from the folding device. Downstream of the drive roller
140 is
another set of vertically staggered transverse rollers 130 to 138. Roller 132
moves
vertically as the band 14 of plastic material emerges from the feeding station
120 and
is commonly referred to as a "dancing roller". A photodetector 141 detects
when the
dancing roller 132 reaches its top position and provides output to the
controller 20.
Positioned between rollers 124 and 126 is a gusset forming device 142
(see Figure 2a). The gusset forming device 142 includes a pair of spaced,
coaxial
discs 144 mounted on a rotatable shaft 146. The discs 144 rotate between the
upper
3o and lower flaps 14a and 14b. An external disc 148 contacts the band 14 of
plastic
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material at the longitudinal fold line between the discs 144 to compress
inwardly the
band of plastic material along longitudinal fold line thereby forming a
gusset.
Downstream of the feeding station 120 is a cutting station 150.
Cutting station includes a planar support surface over which the band 14 of
plastic
material is advanced. The cutting station 150 also includes a reciprocating
mechanical punch 152 which is movable between a retracted position where the
punch
152 is positioned above the band of plastic material and an operative position
where
the punch 152 contacts the band of plastic material. The punch in the
operative
position contacts the lower flap 14b of the band of plastic material and
removes a
generally rectangular or other suitably shaped section 154 of the lower flap
extending
from the peripheral edge of the upper flap 14a to the peripheral edge of the
lower flap.
The punched pieces of the lower flap are removed by a vacuum source (not
shown).
Downstream of the cutting station 150 is a nip 160 constituted by a pair
of drive rollers 162 and 164 between which the band 14 of plastic material
passes. A
conveyor 165 which includes an endless conveyor belt 166 wound around roller
162
as well as roller 170 is positioned downstream of the nip 160. The conveyor
belt 166
presents a generally planar support surface 172. Slightly downstream of the
nip 160
and positioned above the conveyor belt 166 is a sealing station 180, best seen
in
Figures 6 and 7.
Sealing station 180 includes an electrically heated transverse blade 182
having a sharp distal cutting edge 184. The blade 182 extends from the
longitudinal
fold line to the peripheral edge of the upper flap 14a. The transverse blade
182 is
coupled to an actuator 186 which is operable to lower and raise the blade at
preset
times. Guides (not shown) cooperate with the blade 182 to guide the blade as
it is
reciprocated by the actuator 186. The blade 182 is coupled to a pair of
retention
members 188 by way of elastic members 190. The retention members 188 are
preferably formed of sheet metal and are beaked adjacent their lower ends to
form
edges 192 which contact and retain the band of plastic material when the blade
182 is
lowered. A roller 196 is positioned beneath the conveyor belt 166 and is
aligned with
3o the blade 182 to provide an abutment surface for the blade as the blade is
lowered to
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contact the band 14 of plastic material. A hood 198 is positioned above the
blade and
is connected to an aspirator 200 by way of a tube 202 and activated carbon
filter 204
to remove fumes released during sealing and cutting of the band of plastic
material.
Downstream of the sealing station 180 and positioned above the
conveyor belt 166 is a pressing unit 210. The pressing unit 210 includes a
pair of
longitudinally spaced, transverse rotatable shafts 212 and 214. Shaft 212
supports
three pulleys 216 to 220 thereon at laterally spaced locations. A roller 221
is
positioned beneath the forward run of the conveyor belt 166 and is aligned
with the
shaft 212. Shaft 214 also supports three pulleys 222 to 226 thereon at
laterally
to spaced locations. Each pulley 222 to 226 on shaft 214 is in-line with a
pulley on the
shaft 212. Belts 228 to 232 are wound around the in-line pulleys on the shafts
212
and 214. A disc 234 is mounted on the end of the shaft 214.
Downstream of the pressing unit 210 is a nozzle 240 positioned above
and to one side of the conveyor belt 166. The nozzle 240 is connected to a
source of
compressed air (not shown) by way of a valve 242 so that a stream of
compressed air
may be directed towards the conveyor belt. A series of closely spaced rollers
244
support the forward run of the conveyor belt 166 adjacent the nozzle.
A longitudinally oriented, endless retaining belt 250 contacts and runs
along one side of the conveyor belt 166. The retaining belt 250 is wound
around
2o roller 164 of nip 160 as well as around a pulley 260 forming a nip 262 with
roller 170.
The forward and backward runs of the retaining belt 250 pass beneath a disc
264
positioned above the conveyor belt 166 adjacent the pulley 260 as well as
beneath the
disc 234 on the shaft 214.
The filling station 18 (best seen in Figures 8 and 9) includes a feeder
belt 260 wound around rollers 262, one of which is shown. The feeder belt 260
carries abutment profiles 264 thereon to maintain the spacing between products
266
carried by the feeder belt. The feeder belt 260 is in-line with an unloading
belt 270.
Unloading belt 270 is also wound around rollers 272, one of which is shown.
The
feeder belt 260 and unloading belt run alongside the bag making and
positioning
3o machine 16 and pass through an article bagging unit such as that described
in U.S.
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Patent No. 5,483,786. The article bagging unit includes a clamping unit 282
supported on a reciprocating arm 284. The reciprocating arm 284 is actuable to
extend the clamping unit 282 into an inflated bag 290 on the conveyor 165 and
pull
the bag over a product 266 arriving at the end of the feeder belt 260.
The operation of the article bagging machine 10 will now be described.
Initially the sheet plastic material 13 is folded into a band by the folding
device 12
and the band of plastic material is threaded through the bag making and
positioning
machine 16. Once this is completed, the bag making and positioning machine 16
can
be operated to make automatically individual plastic bags from the band of
plastic
l0 material and position the individual bags so that they may be stuffed with
products by
the filling station 18.
During operation, the sheet plastic material 13 is intermittently
unwound from the roll by the drive roller 40 and passes beneath the lower
folding
plate 50. The sheet plastic material is then folded back over the lower
folding plate
about folding edges 54 and 56. At this point in time, a longitudinal fold line
is created
in the sheet plastic material by the comer 58 defined by the two folding edges
54 and
56. The portion of the sheet plastic material which is folded about the
transverse
folding edge 54 changes directions by about 180° while the portion of
the sheet plastic
material folded over the inclined folding edge 56 changes directions by
approximately
90°. The portion of the sheet plastic material folded over the
transverse folding edge
54 passes beneath the upper folding plate 52 and is then folded over the upper
folding
plate 52 about folding edge 60 so that it changes directions by about
90°. The end
result is the formation of the band 14 of plastic material which includes
upper and
lower flaps 14a and 14b with the lower flap projecting laterally beyond the
upper flap
by virtue of the fact that the corner 58 is laterally offset from the central
longitudinal
axis of the sheet plastic material.
As the band 14 of plastic material emerges from the folding device 12
and is intermittently advanced, it is pulled by the drive roller 140 of the
feeding
station 120 whose rotation is synchronized with the drive roller 40 via the
controller
20. The feeding station 120 creates slack in the band 14 of plastic material
to allow
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the drive rollers 162 and 164 to draw intermittently the band of plastic
material at a
rate different than the rate at which the sheet plastic material is unwound
from the roll
32. Specifically, the drive rollers 40 and 140 are rotated until enough slack
develops
in the band of plastic material so that the dancing roller 132 is positioned
at its
lowermost extent. At this time, the drive rollers 40 and 140 are stopped. As
the band
14 of material is drawn from the feeding station 120, the dancing roller 132
moves
vertically. When the photodetector 141 detects the dancing roller 132, the
controller
20 actuates the drive rollers 40 and 140 again to develop slack in the band of
plastic
material. A gusset is also formed along the longitudinal fold line of the band
of
l0 plastic material by the gusset forming device 142.
The drive rollers 162 and 164 are rotated to draw intermittently the
band of plastic material from the feeding station 120 so that the band of
plastic
material is indexed from the feeding station to the cutting station 150, then
to the
sealing station 160 and finally to the conveyor 165. As the band of plastic
material is
indexed to the cutting station 150, the punch 152 is reciprocated so that it
moves
downwardly to contact the lower flap 14b and remove a section of the lower
flap. The
punch 152 is then retracted until the band of plastic material is indexed once
again, at
which time the punch is reciprocated. In this manner, the punch removes
sections of
the lower flap 14b of the band of plastic material at longitudinally spaced
locations.
2o After the band 14 of plastic material has been punched, the band of
plastic material is indexed so that the punched band of plastic material
passes through
the nip 160 and arrives at the sealing station 180. As the band of plastic
material
passes through the nip, the forward run of the retaining belt 250 contacts the
lower
flap 14b of the band of plastic material to retain the band of plastic
material on the
upper surface 172 of the conveyor belt 166. The retaining belt 250 and the
conveyor
belt 166 are indexed with the band of plastic material so that the belts and
the band of
plastic material advance together at basically the same rate. Indexing of the
band of
plastic material is timed such that the band of plastic material stops at the
sealing
station 180 with the removed section of the lower flap 14b being in line with
the
longitudinal axis of the blade 182.
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At this point of time, the actuator 186 is operated to lower the blade so
that the blade contacts the band of plastic material. When the blade 182
contacts the
band of plastic material, the blades seals and cuts through the band of
plastic material.
The seal formed by the blade 182 defines the lateral edges of two adjacent
individual
plastic bags which are closed along three sides and open at one end adjacent
the
protruding lower flap. Since the blade 182 only extends from the longitudinal
fold
line to the peripheral edge of the upper flap, it does not interface with the
retaining
belt 250 which overlies the lower flap. The punched section of the lower flap
completes the transverse cut through the band of plastic material to separate
an
to individual bag from the band of plastic material. Once the band of plastic
material has
been sealed and cut, the actuator 186 retracts the blade until the band of
plastic
material has been indexed again at which time the blade is lowered. In this
manner,
individual bags are formed and separated from the band of plastic material.
Once an individual bag has been separated from the band of plastic
material, the individual bag is carried by the conveyor belt towards the
nozzle 240.
The forward run of the belts 228 to 232 forming part of the pressing unit 210
hold the
individual bag on the conveyor belt 166 inhibiting it from lifting as it
travels to the
nozzle 240. At the same time, the retaining belt 250 holds the lower flap of
the
individual bag against the upper surface of the conveyor belt 166. As the
individual
bag approaches the nozzle, the lower flap of the individual bag is further
urged
towards the conveyor belt 166 by the forward run as well as the backwards run
of the
retaining belt 250 due to the fact that the backwards run of the retaining
belt 250
passes beneath the discs 264 and 234. This helps to maintain securely the
individual
bag in position on the conveyor belt.
After the individual bag has arnved in front of the nozzle 240, the
valve 242 is opened so that the nozzle 240 discharges a stream of compressed
air into
the open end of the individual bag to inflate the bag. When the bag is
inflated, the
reciprocating arm is actuated to extend the clamping unit 282 into the
inflated bag and
the valve 242 is closed. At this stage, the clamping unit 282 is expanding to
hold the
bag and the reciprocating arm 284 is retracted to carry the bag back to the
feeding
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belt. The held bag is then pulled over a product 266 arriving at the end of
the feeder
belt. The clamping unit is then retracted from the bag allowing the bagged
product to
fall to the unloading conveyor 270. Specifics of the clamping unit and the
operation
of the filling station can be found in U.S. Patent No. 5,483,786, the content
of which
is incorporated herein by reference.
If desired, a detector 296 (see Figure 9) for detecting whether each
individual bag inflates when the nozzle 240 discharges the stream of
compressed air
can be provided such as that shown in U.S. Patent No. 5,375,390. In this case,
the
detector 296 includes a ring-shaped elastic contact member 298 positioned
above the
conveyor belt 166 which is raised when each individual bag is inflated after
the valve
242 has been opened. If the valve is opened and the contact member 298 fails
to be
raised, the detector 296 provides a signal to the controller 20 to stop the
article
bagging machine 10.
In addition, if further support for the individual plastic bags is desired,
a clamping unit (not shown) can be provided to one side of the conveyor belt
166
adjacent the nozzle 240 to clamp down onto the retaining and conveyor belts
250 and
166 respectively before the valve 242 is opened.
If it is desired to vary the width of the individual bags, the rate at
which the band of plastic material is indexed can be changed. In order to
monitor the
speed at which the band of plastic material is indexed and drawn from the
feeding
station 120, an encoder is provided on the conveyor for detecting the speed at
which
the conveyor belt is operated. The encoder provides signals to the controller
so that
the speed of the conveyor and hence, the index rate of the band of plastic
material can
be monitored.
Refernng now to Figures l0a to lOc, another embodiment of a
conveyor 165' for use in the bag making and positioning machine is shown. In
this
embodiment, the conveyor is constituted by a plurality of laterally spaced,
endless
belts 300, each of which is wound about a pair of longitudinally spaced
pulleys 302
and 304. The pulleys at each end of the conveyor are mounted on common shafts
306. As shown in these Figures, the conveyor 165' may be horizontally disposed
or
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may be upwardly or downwardly inclined allowing the bag making and positioning
machine 16 to be used with left-handed or right-handed bagging machines. If
desired,
the conveyor 165' can be pivoted downwardly to a vertical inoperative position
to
allow trays holding pre-made bags to be positioned in front of the nozzle 240
so that
they may be inflated and captured by the clamping unit in the filling station
18.
Referring now to Figure 12, a sealing unit 300 for the folding unit 12 is
shown. The sealing unit 300 can be provided on the shelf 36 spaced from the
drive
roller 40. As can be seen, the sealing unit 300 includes a pair of laterally
spaced
transverse rollers 302 and 304 over which the sheet plastic material is wound.
Between the rollers is a generally planar support plate 306 over which a
manually
actuated clamping unit 308, a transverse sealing bar 310 and a pneumatic
clamping
unit 312 are disposed. The pneumatic clamping unit 312 is synchronized with
the
drive roller 40 and holds the sheet plastic material when the drive roller is
stationary.
When a new roll 30 of sheet plastic material is being placed in the folding
device 12,
the new sheet plastic material is wound over the roller 302 and fed beneath
the manual
clamping unit 308 and sealing bar 310 so that the sheet plastic material of
the new roll
overlies the sheet plastic material of the previous roll beneath the sealing
bar 310. At
this stage, the manual clamping unit 308 is actuated to hold the sheet plastic
material
of the new roll in place and the sealing bar is lowered to heat seal and fuse
the sheet
2o plastic material of the new roll to the sheet plastic material of the
previous roll. In this
manner, the joining of the sheet plastic material from the two rolls is
facilitated as
compared to taping manually the sheet material of the two rolls together.
Although the corner 58 of the folding device has been described as
being laterally offset from the central longitudinal axis of the sheet
material, it should
be appreciated by those of skill in the art that if desired, the fold line can
be formed
along the central longitudinal axis of the sheet material. In this case, when
the band of
plastic material is fed to the bag making and positioning machine 16, the
punch 152
removes sections of the upper and lower flaps in a region extending from the
peripheral edges of the upper and lower flaps and partially into the band of
sheet
material. The retaining belt 250 in this case overlies the upper flap of the
band of
CA 02240947 1998-06-04
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sheet of material at the region to hold the band of sheet material at the
sealing
mechanism and the individual bags as they are moved along the conveyor 165 and
inflated by the nozzle 240.
Although the feeding station 120 has been described as including the
gusset forming device, it should be appreciated that this device is optional
and can be
removed if desired.
Furthermore, although the filling station 18 has been described as
including a reciprocating arm which extends the clamping unit into an inflated
bag
and then pulls the bag over a product at the end of the feeder belt 260, it
should be
appreciated that other filling stations can be used. For example, the filling
station can
be of the pushing type to push a product at the end of the feeding belt 260
into the
inflated bag on the conveyor. The bagged product can then be pushed across the
conveyor belt 166 and onto an unloading conveyor 270 on the opposite side of
the
conveyor belt or alternatively can be carried downstream by the conveyor belt
to an
unloading conveyor in line with the conveyor belt 166.
Although the upper folding plate 52 is illustrated as being generally
triangular, it should be apparent to those of skill in the art, that other
plate
configurations can be used which present a folding edge generally forming a
right
angle with the folding edge 56. For example, the upper folding plate 52 may be
in the
2o form of a rectangular bar oriented at about a 45° angle with respect
to the longitudinal
axis of the band of plastic material.
As will be appreciated by those of skill in the art, although the bag
making and positioning machine has been shown receiving the band of plastic
material from folding device 12, the bag making and positioning machine can
receive
the band of plastic material directly from a roll of pre-folded such material
as shown
in U.S. Patent No. 5,373,390. Also, it should also be apparent that the
folding device
may be used to supply folded sheet material to basically any downstream
system.
Although preferred embodiments of the present invention have been
described, those of skill in the art will appreciate that variations and
modifications
CA 02240947 1998-06-04
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may be made without departing from the spirit and scope thereof as defined by
the
appended claims.
