Plastic film bag manufacturing apparatus and associated methods, and plastic film bags produced thereby

An in-line machine for attaching elongated, flexible closure tie elements to the individual bag portions of a laterally folded plastic film web being continuously discharged from a bag forming station, and being forcibly captured by a winder mechanism, engages and drives the moving web toward the winder mechanism by means of mutually spaced inlet, central and outlet drive rollers. During operation of the machine, first and second slack portions of the film web are respectively positioned between the inlet and central rollers, and between the central and outlet rollers. These slack portions are held in vertically looped configurations by a downwardly directed, yielding vacuum force applied thereto. The inlet and outlet rollers are driven at identical speeds corresponding to the constant linear film web output speed from the bag forming station. The central drive roller is alternately started and stopped to sequentially cause a portion of each bag to be momentarily stopped thereon, at which time the machine attaches a tie element to the stopped bag portion. During stoppage of each sequential bag portion, continued rotation of the inlet and outlet rollers lengthens the first film loop and shortens the second film loop. When the central drive roller is restarted it operates to equalize the film loop lengths. In this manner, each bag may be momentarily stopped, for tie element attachment purposes, without altering the constant output and input speeds of the bag forming station and winder mechanisms, and without imposing undesirably high longitudinal tension force on the plastic film web.

BACKGROUND OF THE INVENTION 
The present invention relates generally to the manufacture of plastic film 
bags and, in a preferred embodiment thereof, more particularly provides 
apparatus and methods for attaching to the bags plastic film tie elements 
which, as disclosed in my copending U.S. application Ser. No. 117,209, may 
be tied around the open tops of the bags to tightly close them. 
In the manufacture of plastic film bags it is common practice to form them, 
by continuously extruding plastic film in tubular form, flattening the 
film tube to form a double layer "web", forming lateral weld lines and 
perforation lines across the web to define the individual bags which may 
be subsequently separated from one another at the perforation lines, and 
then laterally folding the web prior to packaging of the bags. The 
laterally folded film web is then typically delivered to a packaging 
station spaced apart from the bag forming station, at a linear receiving 
speed identical to the linear output speed of the bag forming station, 
where it is rolled or folded for packaging. 
For the purpose of attaching accessories to, forming logos or heat seals 
on, or otherwise modifying the individual bags prior to their receipt at 
the packaging station, it is desirable to momentarily stop the web at each 
bag during the performance of a particular modification operation 
thereon--for example, the attachment of a plastic film tie element 
disclosed in U.S. application Ser. No. 117,209 incorporated by reference 
herein. 
There are presently two methods for effecting this necessary momentary 
stoppage of the web as each individual bag passes the modification 
station--neither of which is wholly satisfactory. First, both the bag 
forming station output feed portion and the packaging station input drive 
may be synchronously operated in a start-stop fashion to incrementally 
advance and then stop the entire folded film web section extending between 
these two operating stations. While this is a quite logical approach, it 
significantly slows the overall bag production rate --a rate which must be 
kept as high as possible for profitability purposes. 
Second, a rather complex, high mass, shiftable multiroller structure may be 
utilized to engage and intermittently stop a portion of the folded plastic 
film web between the bag forming station and the winder without slowing or 
interrupting the output and input web travel at these portions of the 
overall bag forming apparatus. However, this high mass roller structure 
must be very rapidly shifted back and forth to stop each individual bag 
received thereby during the high speed bag forming process. Because of the 
rapidity with which the multi-roller structure must be intermittently 
shifted back and forth, very high shift forces result, requiring 
substantial power and precision control. If the multi-roller structure is 
not precisely designed and adjusted, these high shift forces can easily 
tear the travelling film web at one of its perforation lines, creating 
significant down time and waste in the bag manufacturing process. 
In view of the foregoing it can be seen that improved apparatus and methods 
for momentarily stopping each individual bag in the film web, during its 
movement between the bag forming station and the winder, are needed. It is 
accordingly an object of the present invention to provide such improved 
apparatus and methods. 
SUMMARY OF THE INVENTION 
In carrying out principles of the present invention, in accordance with a 
preferred embodiment thereof, an in-line closure tie element attachment 
machine is positioned between a plastic film bag forming station, which 
continuously produces a folded plastic film web divided into individual 
bags by longitudinally spaced perforation lines, and a winder mechanism 
which forcibly captures the folded web at a continuous linear velocity 
equal to the continuous linear output velocity of the bag forming station. 
A web handling portion of the flexible tie element attachment machine 
grips the moving web, and advances it toward the winder, with driven 
roller means including an inlet drive roller, an outlet drive roller 
spaced apart from the inlet drive roller toward the winder mechanism and a 
central drive roller positioned between the inlet and outlet drive rollers 
in a laterally spaced, parallel relationship therewith. 
Positioned beneath these three drive rollers are first and second 
intercommunicating vacuum bins, the first vacuum bin having an open upper 
end positioned generally between the inlet and central drive rollers, and 
the second vacuum bin having an open upper end positioned generally 
between the central and outlet drive rollers. Vacuum pump means are 
connected to lower end portions of the bins for creating vacuum therein 
during machine operation. 
As the folded web is drawn through the web handling portion of the tie 
element attachment machine by the three drive rollers, control means 
associated with the machine rotate the inlet and outlet drive rollers at 
continuous speeds respectively corresponding to the linear web output and 
intake speeds respectively bag forming station and the winder mechanism. 
However, the control means intermittently operate the central drive 
roller, preferably via a stepper motor, in a manner such that the central 
drive roller is sequentially stopped, accelerated to a rotational drive 
speed higher than those of the inlet and outlet rollers, decelerated, and 
then stopped again. 
Each sequential stop-to-stop drive cycle of the stepper motor-drive central 
roller longitudinally advances the portion of the web engaged by such 
roller a predetermined distance so that corresponding longitudinal 
sections of the individual bags, to which flexible tie elements are to be 
attached, are successively and momentarily stopped on the central drive 
roller, at which time a tie element attachment portion of the machine 
affixes a tie element to the stopped bag. 
During operation of the tie element attachment machine first and second 
slack portions of the advancing web are respectively positioned between 
the inlet and central drive rollers, and between the central and outlet 
driver rollers. The vacuums formed in the first and second vacuum bins 
exert yielding, downwardly directed forces on the first and second slack 
web portions, created by air pressure differentials across the web 
portions, pulling web portions downwardly into the bins and positively, 
but rather gently, holding them in downwardly extending first and second 
web loop configurations. 
At the time the central drive roller is initially stopped, to stationarily 
position one of the bags for tie element attachment thereto, the first web 
loop is considerably longer than the second web loop. During tie element 
attachment to the momentarily stopped bag portion of the web, the first 
web loop lengthens, and the second web loop shortens, within their 
respective vacuum bins as the inlet and outlet drive rollers continue to 
be driven at constant rotational speeds, the outlet roller taking slack 
out of the second loop while the inlet roller adds slack to the second web 
loop. The slack takeup capability provided by the vacuum-supported second 
loop prevents the still-running outlet drive roller from imposing tension 
force on the web sufficient to tear it at one of its perforation lines 
positioned on the second loop. Additionally, the slack provided in the two 
web loops permits sequential bag stoppage without altering or interrupting 
the continuous, constant linear web output and intake velocities at the 
bag forming station and the packaging station winder mechanism, 
respectively. Accordingly, a very high bag production rate may be 
maintained. 
After its tie element is attached to the momentarily stopped bag, the 
central drive roller is accelerated, held at a constant elevated speed, 
decelerated, and then re-stopped, as previously described, to stop the 
next longitudinally successive bag thereon for tie element attachment 
thereto This rotation cycle of the central drive roller takes up slack in 
the lengthened first loop, and adds the taken-up slack to the shortened 
second loop, to return the two web loops to their original length 
relationship at the time the central drive roller is stopped at the end of 
its drive cycle. The rapid take-up of the slack in the first loop is 
achieved against the yielding, downwardly directed vacuum force thereon so 
that the web is not torn at one of the perforation lines in its first loop 
portion. Additionally, this slack take-up and loop length readjustment 
does not alter or interrupt the constant velocity of the web entering and 
exiting the tie element attachment machine. 
The control means may be adjusted to compensate for different bag lengths 
being run through the machine, and the vacuum bins are provided with 
movably adjustable front side walls to compensate for changes in the width 
of the particular folded plastic film web upon which the individual bags 
are formed. 
The lengths of the vertically oscillating web loops within the first and 
second vacuum bins are continuously monitored by means of vertically 
spaced series of photoelectric beam transmitters and associated receivers 
which input loop positional information to the control means to permit 
appropriate corrective action to be taken should either of the loops 
become too long or too short during machine operation. 
Additionally, the longitudinal position of each successive bag stopped on 
the central drive roller is continuously monitored by a unique perforation 
detection system which senses the position of the openable end perforation 
line of each bag just before the bag is stopped on the central drive 
roller. The perforation detection system, in a preferred embodiment 
thereof, includes a high voltage electrode member spaced horizontally 
apart from an insulation-housed conductor supported on a central common 
wall structure separating the first and second vacuum bins. The electrode 
is pivotably supported within the first vacuum bin and, in the event that 
the first web loop greatly shortens, is adapted to be engaged by the 
shortened loop and be swung out of the first bin to prevent web tearing or 
separation at one of the perforation lines 
The folded web portion approaching the central drive roller is routed 
between the electrode and the conductor so that the web perforation lines 
successively pass therebetween. A high voltage is suitably impressed on 
the electrode so that as each perforation line vertically passes the 
electrode the electrode discharges to the conductor through the passing 
perforation area, thereby energizing an associated current sensor. 
Energization of the current sensor causes it to transmit an output signal 
to a microprocessor portion of the control means indicating the passage of 
another perforation line past the electrode. This information is 
appropriately correlated to the rotational drive characteristics of the 
central drive roller to continuously monitor the longitudinal orientation 
of each individual bag stopped thereon. 
In the event that the individual bags begin to be longitudinally 
mispositioned relative to the central drive roller at which they 
momentarily stopped (due, for example, to minor drive roller slippage), 
the microprocessor automatically adjusts the rotation of the central drive 
roller to correct the mispositioning. 
The tie element attachment portion of the machine is pivotally mounted on 
the web handling portion thereof, above the inlet and central drive 
rollers, and rotationally supports a supply roll of an elongated plastic 
film web used to form the individual tie elements. During operation of the 
machine the plastic film web on the tie element supply roll is pulled 
therefrom and incrementally advanced, above the inlet and central drive 
rollers and the folded plastic film bag web, toward the winder mechanism. 
As the tie element web approaches the central drive roller a slitter knife 
transversely cuts it into the individual flexible tie elements which are 
sequentially moved to positions directly over the central drive roller, 
and the stopped longitudinal bag sections thereon, by a vacuum belt. 
The inner end of each tie element is then heat welded to a qusseted side 
edge portion of its associated bag, adjacent the openable end thereof, by 
means of a first reciprocating heating die which also forms a slit through 
the inner tie element end portion and the underlying gusseted side edge 
portion of the bag. 
The heat weld on the inner end of the tie element extends through all four 
plastic film layers of the gusseted side edge portion of the associated 
bag. Accordingly, very high strength connection is achieved between the 
flexible tie element and its associated bag. 
To maintain each tie element in an extended position across an outer side 
surface of its laterally folded bag, to facilitate packaging of the bags, 
the outer end of each tie element is releasably restrained against such 
outer side surface of its laterally folded bag. While this releasable 
restraint can be accomplished in a variety of manners, it is accomplished 
in a preferred embodiment of the present invention using a second 
reciprocating heating die which functions to form by both mechanical force 
and thermal deformation, a series of "dimples" in each outer tie element 
end which extend into corresponding depressions formed in the underlying 
layer of plastic bag film. The interlock between these dimples and bag 
film depressions keep the tie elements from flapping about during 
packaging of their associated bags, but later permit each outer tie 
element end to be easily separated from its associated bag without tearing 
a hole in the bag. 
When a bag is ultimately detached from the laterally folded plastic film 
web, the outer tie element is simply pulled outwardly from and detached 
from the bag. The tie element is then looped around the open bag end to 
form a tightening loop therearound. Finally, the now detached outer tie 
element end is passed through the slit in the inner tie element end and 
pulled to tighten the tie element loop around the open bag end and tightly 
close it. The slit length is preferably somewhat shorter than the tie 
element width so that as the tie element is passed through the slit the 
tie element is crumpled and gathered in a manner inhibiting loosening of 
the tie element loop around the bag. 
The tie element attachment machine of the present invention may be 
conveniently placed "in-line" in an existing plastic film bag forming 
system, and the web handling portion of the machine may be used to 
sequentially stop spaced longitudinal sections of the continuously moving 
bag web for purposes other than tie element attachment.

DETAILED DESCRIPTION 
Schematically illustrated in FIG. 1 is a plastic film bag forming station 
20 which, during operation thereof, outputs a laterally folded plastic 
film web 22 (see also FIGS. 2 and 3) at a constant linear longitudinal 
speed V.sub.1. The bag forming station 20 includes a plastic extrusion die 
24 which continuously extrudes, in an upward direction, a plastic film 
tube 26. Tube 26 is passed upwardly through a gusset forming structure 27, 
and then between a pair of flattening rollers 28 and 30, to convert the 
tube to a flattened tube or "web" 32 (see also FIG. 1A) exiting the 
rollers 28, 30 and having a side edge portion 42 with an inwardly 
extending gusset 31 extending along its length, the gusset being defined 
by four layers of plastic film. After its exit from the rollers 28 and 30, 
the web 32 is sequentially passed over the rollers 34 and 36 and fed 
through a heat sealing, folding and perforation apparatus 38. 
The schematically depicted apparatus 38, as its name implies, sequentially 
performs three operations on the web 32 traversing the apparatus. First, 
it forms on the web a longitudinally spaced series of laterally extending 
heat seal weld lines 40, each of which extends between the side edge 42 of 
the web 32 and its opposite side edge 44 (see FIG. 4). 
Next, as cross-sectionally illustrated in FIG. 4, the web 32 is laterally 
folded along the longitudinally extending fold lines 46 and 48, the fold 
line 46 being laterally aligned with the side edge 44, and the fold line 
48 being laterally inset from the side edge 42. As best seen in FIG. 4, 
the lateral inset of the fold line 48 causes a side edge portion 42.sub.a 
(containing the gusset 31) to extend laterally beyond the balance of the 
laterally folded, flattened film tube which ultimately defines the 
laterally folded plastic film web 22. The number of folds in the folded 
web 22 are, of course, merely representative--a greater or lesser number 
of folds could be formed. 
After the web 32 has been heat sealed along lines 40, and laterally folded 
as just described to create the folded web 22, the apparatus 38 operates 
to form on the folded web 22 a longitudinally spaced series of laterally 
extending perforation lines 50 which extend completely across and through 
the laterally folded, web 22. As illustrated in FIG. 2, each of the 
perforation lines 50 is positioned leftwardly adjacent one of the heat 
seal lines 40. Accordingly, the heat seal lines 40 and the perforation 
lines 50 form on the laterally folded plastic film web 22 exiting the 
apparatus 38 a longitudinal series of laterally folded individual plastic 
film bags B which may ultimately be separated from one another by tearing 
the film web 22 along the perforation lines 50. When this is done, each 
individual bag, in the usual manner, has an openable end extending along 
one of the perforation lines 50, and a closed, opposite end extending 
along one of the heat seal lines 40. 
Referring again to FIG. 1, the laterally folded plastic film web 22 exiting 
the apparatus portion 38 of the bag forming station 20 is forcibly 
captured in a conventional winder mechanism 52, spaced apart in a leftward 
direction from the bag forming station apparatus 38, at a constant linear 
speed V.sub.2 equal to the linear output velocity V.sub.1 of the film web 
22 from the bag forming station 20. To provide tension control therefor, 
the folded web 22 is passed beneath a stationary roller 53, and over a 
pivotally mounted dancer roller 54 prior to being drawn into the winder 
mechanism 52 wherein it is wound upon a suitable storage roll (not 
illustrated). 
Operably interposed between the bag forming station apparatus 38 and the 
winder mechanism 52 is a tie element attachment machine 60 which, as 
subsequently described, is utilized to secure to each of the individual 
bags B, adjacent its openable end, a plastic film closure tie element 62 
as illustrated in FIGS. 3 and 5 which are top plan views of the laterally 
folded plastic film web 22 as it exits the machine 60. Machine 60 
basically comprises a web handling portion 60.sub.a, and a closure tie 
element attachment portion 60.sub.b which is mounted atop the web handling 
portion 60.sub.a and is pivotable relative thereto between a lowered 
operating position (shown in solid lines in FIG. 1) and a raised access 
position (shown in phantom in FIG. 1). 
As will be seen, the web handling portion 60.sub.a operates to engage and 
leftwardly drive a longitudinally central portion of the folded web 22, 
positioned between the apparatus 38 and the winder mechanism 52, and to 
sequentially and momentarily stop each of the individual bags B and 
stationarily position a longitudinal section thereof for attachment 
thereto of the bag's associated closure tie element 62. Importantly, this 
intermittent stoppage of each of the individual bags moving from the 
apparatus 38 to the winder mechanism 52 is effected without appreciably 
altering the web output and intake linear velocities V.sub.1 and V.sub.2 
and without imposing upon the longitudinally moving web 22 undesirably 
high longitudinal tension forces which might otherwise tear the web at one 
of its perforation lines 50. 
The tie element attachment portion 60b of the machine 60 is appropriately 
synchronized with the web handling portion 60a, and is operative to form 
the individual tie elements 62, from a plastic film supply roll 64, and 
attach the formed tie elements to the sequentially stopped longitudinal 
sections of the individual bags B. 
Before describing in detail the structure and operation of the tie element 
attachment machine 60, certain features of the tie elements 62 will be 
briefly described with reference to FIGS. 1 and 5-8. The representatively 
illustrated tie element supply roll 64 is formed from a lateral half of an 
elongated, flattened plastic film tube which has been cut along its 
central longitudinal axis with a heated slitting knife or wire. The 
lateral flattened web half used to form the tie element supply roll 64 
thus defines an elongated, dual layer plastic film web 68 (FIG. 10) having 
a folded side edge 70 (FIG. 9), and an opposite, heat sealed edge 72 which 
was previously formed by the heated slitting knife or wire. It will be 
appreciated that, depending upon how the tie element web 68 was initially 
formed, both of the edges 70, 72 could be heat sealed edges. As will be 
seen, the web 68 is drawn through the tie element attachment portion 
60.sub.b of the machine 60 and is laterally cut into elongated strips that 
define the tie elements 62 which are secured to the individual bags B. 
As best seen in FIGS. 5-7, each of the tie elements 62 has an inner end 
portion 62.sub.a which includes a portion of the folded side edge 70 of 
the tie element web 68 and overlies the overhanging side edge portion 
42.sub.a of the laterally folded plastic film web 22. The tie element 
inner end portion 62.sub.a is firmly secured to the web side edge portion 
42.sub.a by means of a circular heat web 74. As best illustrated in FIG. 
6A, the held weld 74 extends through all four plastic film layers of the 
gusseted side edge portion 42.sub.a of the folded web 22. 
A longitudinally extending slit 76 is formed through the tie element end 
portion 62.sub.a, and the underlying web side edge portion 42.sub.a, and 
is positioned within the circular heat weld 74. From its secured inner end 
portion 62.sub.a, the tie element 62 extends longitudinally across the 
upper side surface of the folded web 22, with the tie element 62 being 
parallel to and adjacent the perforation line 50 that defines the openable 
end of the individual bag with which the particular tie element is 
associated. 
The anchoring of the inner end of each tie element 62 (by the circular heat 
weld line 74) to all four layers of the gusseted side edge portion 42a of 
the folded web 22 provides a very strong interconnection between each tie 
element and its associated bag B. However, if desired, the side edge 
gusset 31 could be omitted (by omission of the gusset forming structure 27 
shown in FIG. 1) so that the overhanging side edge portion of the folded 
web 22 would have only two plastic film layers (see the alternate side 
edge portion 42b in FIG. 4A). The inner end of each tie element 62 would 
then be heat welded along the circular weld line 74) to the two film 
layers of the modified side edge portion 42b. 
Each of the tie elements 62 also has an outer end portion 62.sub.b, 
containing a portion of the heat sealed side edge 72 of the tie element 
web 68, which is positioned laterally inwardly of the web fold 46. The 
heat sealed joint at the outer end of the tie element 62 is not 
particularly strong due to the fact that it was formed by a heated 
slitting knife or wire. Accordingly, a pair of laterally extending heat 
weld lines 78 are formed on the tie element 62 adjacent its outer end, in 
a manner subsequently described, to more firmly intersecure the two 
plastic film layers of the tie element in that region. 
To releasably restrain the tie element 6 in place across the top side of 
the laterally folded plastic film web 22, so that the web 22 and the 
attached tie elements 62 ma be smoothly drawn into the winder mechanism 
52, five small dimples 80 (see FIGS. 7 and 7A) are formed in the outer tie 
element end 62b and are received in corresponding depressions 80a in the 
plastic web film layer beneath the tie element. As subsequently described, 
a heated die is used to form these dimples and depressions which are 
formed by a combination of mechanical force and thermoplastic distortion 
without appreciably heat welding the tie element end 62b to its associated 
bag. Accordingly, the tie tearing the bag. To use a tie element 62 to tie 
off and close the open end of its associated bag B, the outer end of the 
tie element 62 is simply pulled apart from the bag film layer to which it 
is releasably restrained by the interlocking dimples 80 and depressions 
80a. After this is done, the tie element 62 remains very firmly anchored 
to its associated bag B by the circular heat weld 74 at the inner tie 
element end. 
As illustrated in FIG. 8, the tie element 62 may then be used to tightly 
close and seal the open end 82 of its associated bag B by simply wrapping 
the tie element 62 around the open bag end, passing the outer tie element 
end portion 62b through the slit 76 to form a loop 84 around the open bag 
end, and then firmly pulling on the tie element to cinch the loop around 
the bag. The length of the slit 76 is preferably made somewhat shorter 
than the width of the tie element 62 which tends to crumple and gather the 
tie element as indicated at 62.sub.c, at its juncture with the slit, 
thereby substantially inhibiting loosening of the bag-closing tie element 
loop 84. 
The illustrated closure tie element 62 is merely representative of a wide 
variety of tie element structures which could be attached to the 
individual bag portions of the laterally folded plastic film web 22. A 
variety of alternate closure tie element configurations are illustrated 
and described in U.S. application Ser. No. 117,209 which has been 
incorporated herein by reference. 
Referring now to FIGS. 1 and 9, the tie element attachment machine 60 
includes a generally rectangular support frame structure 86 which is floor 
supportable on four vertically adjustable support feet 88 positioned at 
the corners of the support frame structure. The web handling portion 
60.sub.a of the machine 60 is carried by a front side portion of the frame 
structure 86 and includes three drive roller members--an inlet drive 
roller 90, a central drive roller 92, and an outlet drive roller 94. As 
illustrated, the rollers 90, 92 and 94 extend horizontally, are laterally 
spaced apart, and are in essentially the same horizontal plane. 
The three drive rollers longitudinally extend in a front-to-rear direction 
relative to the support frame structure 86, and are pivotally supported at 
their opposite ends on support frame portions 96 and 98. Roller 92 is 
spaced leftwardly from roller 90, and roller 94 is spaced leftwardly from 
roller 92. As schematically depicted in FIG. 12, the roller 90 is driven 
in a counterclockwise direction by a motor 100, roller 92 is driven in a 
counterclockwise direction by a stepper motor 102, and roller 94 is driven 
in a counterclockwise direction by a motor 104. 
Supported by a front side portion of the support frame structure 86 
directly beneath the rollers 90, 92 and 94 are a side-by-side pair of 
metal vacuum bins 106 and 108 (cross-sectionally illustrated in FIG. 11), 
bin 108 being positioned immediately to the left of bin 106. The vacuum 
bins 106, 108 have generally rectangular configurations, open top ends 110 
and 112, bottom walls 114 and 116, a common central side wall 118, outer 
right and left side walls 120 and 122, rear walls 124 and 126, and front 
side walls 128 and 130. As illustrated in FIG. 11, roller 90 is positioned 
above and tangent to the bin wall 120, the roller 92 is positioned above 
the top end of the central bin wall 118 and is tangent to its opposite 
sides, and the roller 94 is positioned above and tangent to the bin wall 
122. 
For purposes later described, a vacuum pump 132 (FIG. 9) is supported by 
the frame structure 86 generally behind the left vacuum bin 108 and has an 
inlet 134. The inner ends of a pair of flexible vacuum hoses 136 and 138 
are connected to the inlet 134, and the outer ends of the hoses 136, 138 
are respectively connected to the bottom vacuum bin walls 114, 116 and 
communicate with the interiors of the bins 106, 108. The interiors of the 
vacuum bins 106, 108 communicate with one another via a transfer passage 
140 formed through a lower end portion of the common central bin wall 118 
and functioning to generally equalize the vacuums drawn in the two bins. 
Also for purposes later described, a vertically spaced series of five 
photoelectric beam transmitting units 142, 144, 146, 148 and 150 are 
mounted on the right bin side wall 120 and are adapted to leftwardly 
transmit photoelectric beams 152 across the interior of vacuum bin 106 for 
receipt by a vertically spaced series of beam receiving members 142.sub.a 
-150.sub.a mounted on the central bin wall 118. In a similar fashion, a 
vertically spaced series of photoelectric beam transmitters 154, 156, 158, 
160 and 162 are mounted on the left bin side wall 122 and are operative to 
rightwardly transmit photoelectric beams 164 across the interior of the 
left vacuum bin 108 for receipt by a vertically spaced series of 
corresponding beam receiving units 154.sub.a -162.sub.a. 
Referring now to FIGS. 9 and 11, the web handling portion 60.sub.a of the 
tie element attachment machine 60 also includes a pair of pinch rollers 
166 and 168 which are rotationally carried at their outer ends by arm 
members 170, 172. The inner ends of the arm members 170, 172 are pivotally 
carried by a pair of upright support plate structures 174 and 176 which 
project upwardly from left end sections of the support frame portions 96, 
98. As illustrated, the arm members 170, 172 are downwardly pivotable to 
respectively position the pinch rollers 166, 168 against upper portions of 
the outlet drive roller 94 and the central drive roller 92. A third pinch 
roller 178 is similarly carried on a pair of arms 180 pivotally secured at 
their inner ends to a pair of upright support bracket structures 182, 184 
positioned along right end sections of the support frame portions 96, 98. 
The arms 180 are downwardly pivotable to position the pinch roller 180 
against an upper portion of the inlet drive roller 90. 
Referring now to FIGS. 1 and 11, the laterally folded plastic film web 22 
exiting the bag forming station apparatus 38 is extended through a 
conventional web guide apparatus 186, secured to a right end portion of 
the support frame structure 86, which functions to automatically maintain 
proper lateral alignment of the web during operation of the overall 
system. Upon leftwardly exiting the web guide apparatus 186, the web 22 
sequentially passes beneath a guide roller 188, between the drive and 
pinch roller sets 90 and 180, 92 and 168, and 94 and 166, beneath a guide 
roller 190, beneath the stationary roller 53, and over the pivotally 
mounted dancer roller 54 and upwardly into the winder mechanism 52. 
Utilizing the subsequently described control system 192 (FIG. 12), 
start-up of the web handling portion 60.sub.a of the machine 60 is 
effected as follows. 
The web 22 is loaded into the tie element attachment machine 60 by 
initially passing the web under roller 188, resting the web atop the three 
drive rollers 90, 92 and 94, and passing the web beneath roller 190 and 
operatively connecting it to the winder 52. A switch 331 on a main control 
panel 332 (FIG. 15) is then moved to its "LINE" position which, via a 
microprocessor 198 (FIG. 12), initiates the operation of rollers 90 and 94 
at rotational speeds corresponding to the linear web velocity V.sub.1. 
When it is desired to attach tie elements to the web 22, an operator moves 
the switch 331 from its "LINE" position to its "RUN" position. This 
signals the microprocessor 198 to energize the vacuum pump 132 (FIG. 9) 
and slow the rotation of roller 94 via a output signal 208 transmitted to 
its speed controller 210. The slowing of roller 94 causes the web 22 to be 
pulled downwardly into the vacuum bin 106. In a manner subsequently 
described, when web 22 downwardly reaches a predetermined level within bin 
106, the microprocessor 198 transmits an output signal 200 to speed 
controller 202 (FIG. 12) to rotationally "step" the roller 92 at a 
rotational velocity greater than the linear velocity V.sub.1, permitting 
the web 22 to be vacuum-drawn downwardly into bin 108 into a looped 
configuration 204 until, in a manner subsequently described, the 
corresponding web loop 194 in bin 106 is shortened and the loops 194 and 
204 are in their relative length relationship illustrated in FIG. 11. In 
such length relationship the loop 204 is considerably longer than loop 
194. 
After this initial length relationship between the web loops 194, 204 is 
achieved, the microprocessor 198 signals speed controller 210 to operate 
roller 94 at a rotational speed equal to that of roller 90 to maintain the 
web loops in this initial length relationship. Upon attainment of this 
condition, the switch 331 is moved to its "RUN" position which, via the 
microprocessor 198, lowers the tie element portion 60.sub.b of machine 60 
to be lowered into its operative position. 
During the start-up, with the folded plastic film web 22 being outputted 
from the sealing, folding and perforating apparatus 38, the motor 100 
rotationally drives the inlet roller 90 at a constant torque and at a 
counterclockwise, variable rotational speed corresponding to the linear 
web output speed V.sub.1 so that the web takeup speed of the roller 90 is 
equal to the linear web output speed from the apparatus 38. The 
above-described slowing of roller 94 forms a slack portion of the web 22 
between the rotating drive roller 90 and the stationary central drive 
roller 92. The operation of the vacuum pump 132 (FIG. 9) creates a 
yielding vacuum force within the vacuum bin 106 which draws this slack web 
portion downwardly into bin 106 and gently holds it in the illustrated, 
downwardly looped configuration 194 (FIG. 11). As the roller 90 continues 
to rotate, the vertical length of the web loop 194 downwardly increases. 
The increasing length of the web loop 194 is continuously monitored by the 
photoelectric beam receivers 142.sub.a -150.sub.a supported on the central 
bin wall 118. It can be seen in FIG. 11 that as the web loop 194 extends 
further downwardly within the bin 106 it sequentially blocks downwardly 
successive ones of the photoelectric beams 152. When the lower end of the 
loop web 194 downwardly reaches a predetermined vertical level within the 
bin 106, a combinative signal 196 (FIG. 12) is transmitted from the 
receivers 142.sub.a -150.sub.a to a microprocessor 198, the signal 196 
indicating that the vertical length of the web loop 194 has reached its 
desired magnitude. 
Upon receiving the signal 196, indicating that the web loop 194 has reached 
its desired initial length within the bin 106, the microprocessor 198 
responsively transmits an output signal 200 to the speed controller 202 
which in turn, operates the motor 102 to step the central drive roller 92 
at a faster speed than the inlet roller 90, thereby initiating the 
formation of web loop 204. The stepped rotation of the central drive 
roller 92 increases the length of the resulting slack web portion between 
the rollers 92, 94, the vacuum force within the left bin 108 exerting a 
yielding downward force on this second slack web portion to convert it to 
the second downwardly extending web loop 204. When the bottom end of the 
web loop 204 is properly positioned within bin 108 (see FIG. 11), the 
photoelectric receivers transmit through the microprocessor 198 a 
combinative signal 206 indicative of the fact that the left web loop 204 
has now reached its desired initial vertical length. 
Microprocessor 198 then responsively transmits an output signal 208 to a 
speed controller 210 which operates the motor 104 to initiate a change in 
rotation of the outlet drive roller. The roller 94 is driven at a 
rotational speed identical to that of the inlet drive roller 90 via the 
operation of a magnetic speed sensor 212 that monitors the rotational 
speed of a small gear member 214 secured to the front end of the inlet 
drive roller 90 for rotational therewith. Speed sensor 212 responsively 
transmits to the microprocessor 198 a rotational speed-indicative output 
signal 216 which, in a feedback manner, is operative to adjust the output 
signal 208 to the speed controller 210, to thereby equalize the rotational 
speeds of the inlet and outlet drive rollers 90, 94. With the three drive 
rollers 90, 92 and 94 being operated at essentially constant speeds, the 
heights of the web loops 194 and 204 are maintained in their length 
relationship illustrated in FIG. 11 during the start-up phase of machine 
operation. 
The microprocessor 198, and the speed controllers 202 and 210, are 
conveniently positioned within a rear side portion of the support frame 
structure 86 (FIG. 9) along with various other control components 
generally indicated by the reference numeral 218. After the previously 
described start-up procedure has been accomplished, the web handling 
position 60.sub.a of the machine 60 is converted to its normal operating 
mode by moving switch 331 to its "RUN" position. In this operating mode, 
the inlet and outlet drive rollers 90, 94 are still rotated at constant 
and essentially identical speeds, but the central drive roller is 
sequentially started and stopped to sequentially and stationarily position 
longitudinal sections of each individual bag B, adjacent its perforation 
line 50 that defines its openable end, to ready such longitudinal bag 
sections for the attachment thereto of the tie elements 62 in a manner 
subsequently described. 
Quite importantly, this sequential stoppage of each individual bag B at the 
central drive roller 92 is accomplished without appreciably altering the 
constant output and intake velocities V.sub.1 and V.sub.2 of the 
longitudinally moving folded plastic film web 22 as it approaches and 
exits the tie element attachment machine 60. Additionally, as will be 
seen, due to the unique formation of the web loops 194 and 204 such 
individual bag stoppage is effected without imposing upon the web 22 
undesirable longitudinal tension forces which might otherwise tear the web 
at one of its perforation lines 50. The unique achievement of these two 
very desirable results will now be described in conjunction with FIGS. 11 
and 11A. 
In FIG. 11A, the central drive roller 92 has been stopped, during the 
continuing rotation of the inlet and outlet drive rollers 90 and 94, to 
thereby momentarily hold the bag portion B.sub.1 thereon with the openable 
end perforation line 50.sub.b of the bag B.sub.1 being rightwardly 
adjacent the central drive roller 92, and the opposite end perforation 
line 50.sub.a of the bag B.sub.1 being positioned upon the web loop 204 
being vacuum-drawn downwardly into the bin 108 through its open upper end 
112. The longitudinal section of the stopped bag B.sub.1 positioned atop 
the now stationary central drive roller 92 corresponds to the longitudinal 
section of such bag to which its closure tie element 62 will be affixed. 
During its momentary stoppage, the central drive roller 92 does not, of 
course, continue to drive a left side portion of the right web loop 194 
into the left vacuum bin 108. However, the continued rotation of the inlet 
and outlet drive rollers 90, 94 continues to feed the web 22 into the 
right vacuum bin 106, and withdraw the web 22 from the left vacuum bin 
108. This functions to lengthen the web loop 194, while shortening the web 
loop 204, as respectively indicated by the arrows 220 and 222 in FIG. 11A. 
The left web loop 204 is shortened against the downwardly directed vacuum 
force imposed thereon by the vacuum pump 132. Accordingly, the tension 
force exerted on the web loop 204 by the continuously rotating outlet 
drive roller 94 in insufficient to tear any of the web perforation lines 
disposed within the left vacuum bin 108--all the outlet drive roller 94 
does during this period in which the central drive roller 92 is 
momentarily stopped, is take up the slack in the left web loop 204. 
After its tie element 62 is secured to the momentarily stopped bag B.sub.1, 
as monitored by an appropriate sensor 224 (FIG. 12), the sensor 224 
transmits an output signal 226 to the microprocessor 198 indicating that 
the tie element has been attached. The roller 92 is not commanded to 
rotate until photocell 150 is covered by web loop 194, at which time the 
output signal 196 is transmitted to microprocessor 198. When the signal 
196 is received by the microprocessor, the microprocessor automatically 
adjusts its output signal 200 to the speed controller 202 to operate the 
stepper motor 102 in a manner such that the central drive roller 92 is 
sequentially started and rotationally accelerated to a counterclockwise 
rotational speed higher than the speeds of the inlet and outlet drive 
rollers 90 and 94, maintained at this elevated speed for a predetermined 
time period, decelerated, and stopped. 
The result of this speed control cycle of the central drive roller 92 is 
that at the moment of its stoppage subsequent to the attachment of the tie 
element to the bag B.sub.1, the right web loop 194 has been re-lengthened, 
and the left web loop 204 reshortened, to their original lengths as 
depicted in FIG. 11. Additionally, the next bag B.sub.2 has been stopped 
at the central drive roller 92, with the openable end perforation line 
50.sub.c of bag B.sub.2 positioned rightwardly adjacent the roller 92, and 
the opposite perforation line 50.sub.b being now positioned within the 
left vacuum bin 108. 
After this stoppage of the central drive roller 92, which readies the bag 
B.sub.2 for the attachment of its tie element thereto, the web loops 194, 
204 again begin to respectively lengthen and shorten as illustrated in 
FIG. 11A. The elevated speed level of the central drive roller 92, which 
shortens the web loop 194, does not impose undesirably high longitudinal 
tension force on the loop 194, since the roller 92 merely takes the slack 
out of the previously lengthened loop 19 against the yielding, downwardly 
directed vacuum force on such loop within the right vacuum bin 106. 
It can thus be seen that the web handling apparatus of the present 
invention, by means of the formation and length control of the two web 
loops 194 and 204, permits the sequential stoppage of each individual bag 
without overstressing the web 22 or appreciably altering the linear output 
and intake speeds V.sub.1 and V.sub.2 of the web. 
It will be appreciated that the microprocessor 198 may be easily programmed 
to operate the speed controller 202 such that, during each period in which 
the drive roller 92 is rotated, the stepper motor 102 inputs the proper 
number of rotational "steps" to the central drive roller 92. The roller 92 
sequentially advances the web a distance equal to the length of the 
individual bags being produced, and that the time period between stoppages 
of the roller 92 is coordinated to essentially equalize the lengths of the 
web loops 194, 204 each time the central drive roller is stopped. 
In addition to precisely controlling each web advancement length of the 
roller 92, it is also important to insure that a each individual bag is 
stopped at the central drive roller, the openable end perforation line of 
such bag is properly positioned relative to the stopped roller so that 
each attached tie element is properly positioned on its associated bag. In 
the present invention, this is achieved by the use of a specially designed 
perforation detection system 230 which is illustrated in FIGS. 11, 11A, 13 
and 14. 
The perforation detection system 230 includes a high voltage electrode 
member encased in an insulation tube 232 which is mounted on the outer end 
234 of an L-shaped support arm 236 which extends rearwardly through an 
opening 238 formed in the rear side wall 124 of the right vacuum bin 106 
adjacent its upper end and the upper end of the central bin wall 118. The 
inner end 240 of the support arm 236 is positioned behind the bin wall 124 
and is secured to a pivot pin member 242 which permits the support arm 236 
to pivot about a horizontal axis, as indicated by the double-ended arrow 
244 in FIG. 13, between an operating position shown in FIG. 13 and a 
stowage position in which the electrode 232 and the outer end 234 of the 
support arm 236 are rearwardly pivoted through the bin wall opening 238 
and are withdrawn from the vacuum bin 106. 
With the support arm 236 forwardly pivoted to its operating position, the 
portion of the support arm extending forwardly through the bin wall 
opening 238 rests upon and is supported by a horizontally extending tab 
portion 246 of the rear side bin wall 124, and the left or discharge end 
232.sub.a of the electrode 232 is positioned slightly rightwardly of the 
central bin wall 118. 
Directly to the left of the inner electrode end 232.sub.a is a circular 
opening 248 formed in the central bin wall 118. As cross-sectionally 
illustrated in FIG. 14, a cylindrical insulator member 250 has a boss 
portion 252 positioned within the bin wall opening 248, and a grounded 
cylindrical metal conductor member 254 extends coaxially through the 
insulator member 250, the exposed right end of the conductor member 254 
facing the inner end 232.sub.a of the electrode 232. 
As illustrated in FIGS. 11 and 14, a left side portion of the right web 
loop 194 is routed upwardly between the electrode 232 and the insulator 
250 onto the central drive roller 92. Accordingly, during operation of the 
tie element attachment machine 60 the web perforation lines 50 are 
sequentially passed between the electrode 232 and the conductor 254. The 
electrode 232 is connected via a lead 256 to a high voltage power supply 
device 258 which functions to create a high voltage potential across the 
gap between the electrode 232 and the conductor 254. Electrical discharge 
between the electrode 232 and the conductor 254 is normally prevented by 
the high dielectric constant of the plastic film material of the web 22 
positioned in such gap. 
However, each time a perforation line passes through this gap, an 
electrical discharge occurs from the electrode 232, through the 
perforation line, to the conductor 254, and then through the conductor to 
ground. This creates a current flow from the electrode to ground, which is 
sensed by a current sensor 260 that responsively transmits a 
current-indicative output signal 262 to the microprocessor 198 (see FIG. 
12). In this manner, a precise monitoring of the position of the openable 
end perforation line of each of the individual bags is achieved so that 
when each individual bag is stopped at the central drive roller 92, the 
longitudinal section of each individual bag to which its tie element is to 
be attached is also precisely positioned. 
Should the control system 192 detect a deviation in the desired position of 
the openable end perforation line 50 when a particular bag is stopped at 
the central drive roller (such deviation being caused for example, by 
roller slippage) the microprocessor 198 automatically functions to adjust 
the signal 200 being transmitted to the speed controller 202 to 
momentarily increase or decrease the counterclockwise rotational steps of 
the roller 92 to readjust the stopped bag position on the central drive 
roller 92, and correspondingly adjust the signal 200 to increase or 
decrease the total number of rotational "steps" imparted to the central 
drive roller 92 during one star-stop rotational cycle thereof, thereby 
properly readjusting the longitudinal operation of each individual bag as 
it is stopped at the central drive roller 92. 
Normally, the rotational speeds of the inlet and outlet drive rollers 90, 
94 are the same. However, at certain web velocities and bag lengths, the 
web loop 204 in the vacuum bin 108 may become too long or too short during 
the tie element attachment process. When the web 204 is too long (such as, 
for example the photocells 160 or 162 are covered by the loop 204), the 
microprocessor is signalled and responsively causes the controller 210 to 
temporarily increase the rotational speed of roller 94. In a similar 
fashion, when web loop 204 becomes too short (such as, for example, when 
photocells 156 and 158 are uncovered), an appropriate signal is sent to 
the microprocessor which, in turn, temporarily slows the rotational speed 
of roller 94. 
The pivotal mounting of the electrode 232 on the L-shaped support arm 236 
functions to prevent the web 22 from being torn at one of its perforation 
lines 50 in the event that the right web loop 194 is shortened to an 
extent that its lower end contacts the outer end 234 of the support arm 
236. In the event that this occurs, the web merely pivots the support arm 
236 rearwardly to its stowed position in which it is disposed entirely 
behind the bin wall 124 by movement through the bin wall opening 238 as 
previously described. 
The control system 192 described in conjunction with FIG. 12 is, of course, 
adjustable to compensate for different bag lengths being driven through 
the web handling portion 60.sub.a of the tie element attachment machine 60 
the bag length being the distance between sequentially adjacent pair of 
perforation lines 50. The web handling portion 60.sub.a may also be easily 
adjusted to compensate for folded webs of different widths. This width 
adjustment is achieved in the present invention by providing means for 
selectively varying the effective front-to-rear widths of the vacuum bins 
106 and 108. Such bin width adjustment is obtained by mounting the front 
bin walls 128, 130 for selective front and rear movement relative to the 
balance of the bins. 
Referring now to FIG. 9 upper and lower support members 264 and 266 are 
suitably secured between the central bin wall 118 and the outer side walls 
120, 122 of the vacuum bins. Internally threaded nut members 268, 270 are 
captively retained on the upper and lower support members 264, 266 for 
rotation relative thereto and threadingly receive elongated externally 
threaded rod members 272, 274 welded at their inner ends to the movable 
front bin walls 128, 130. Along their opposite vertical sides, the front 
bin walls 128, 130 are provided with resilient seal members 276 which 
slidingly engage the opposite left and right side walls of each bin. 
Sprocket members 278, 280 are respectively secured to the upper and lower 
nut members 268 and 270, and are drivingly interconnected by suitable 
chains 282. The upper nut members 268 have secured thereto suitable 
adjustment knobs 284 which may be rotated to effect forward or rearward 
movement of their associated front bin walls. For example, as viewed in 
FIG. 9, clockwise rotation of one of the adjustment knobs 284 effects 
forward movement of its associated front bin wall, while counterclockwise 
rotation of the adjustment knob causes rearward movement of the front bin 
wall. In this manner, front-to-rear width adjustment of the two vacuum 
bins may be obtained so that the front-to-rear width of the bins is just 
slightly larger than the width of the folded plastic film web being used 
in a particular bag run. This width adjustment capability assures that the 
downward vacuum force applied to the web loops in each of the bins is 
efficiently applied to such loops. 
The web handling apparatus 60.sub.a just described is particularly well 
suited to its illustrated use in handling the folded plastic film web 22 
used in the in-line production of plastic bags in which it is necessary to 
momentarily stop longitudinally spaced apart sections of the continuously 
moving web to secure flexible tie elements to the stopped web sections. 
However, it will be readily appreciated that the unique structure and 
operation of the web handling apparatus would also be quite useful for the 
performance of operations other than tie element attachment--for example, 
in printing, attachment of auxiliary components of other types, and the 
like. 
Turning now to FIGS. 9 and 10, the tie element attachment portion 60.sub.b 
of the machine 60 will be described in detail. The support spindle 66 of 
the tie element supply roll 64 is rotationally supported on the upper ends 
of a pair of upright support bars 286 extending upwardly from the support 
brackets 182, 184 positioned at a right front corner portion of the 
support frame structure 86 a previously described. Extending leftwardly 
from the support brackets 182, 184 are a spaced pair of support arm 
structures 288. The support arm structures 288 are secured to the brackets 
182, 184 and are pivotally carried by a support rod structure 290 so that 
the tie element roll 64, the support bars 286, and the support arm 
structures 288 may be pivoted between the solid line, lowered operating 
position of the tie element attachment portion 60.sub.b and its dotted 
line raised access position schematically depicted in FIG. 1. 
As best seen in FIG. 10, the tie element web 68 extends downwardly from the 
supply roll 64 and is passed under a dancer roller 291 which is pivotally 
carried on support arms 292 secured at their inner ends to the brackets 
182 and 184. The web 68 then passes upwardly around an upper guide roller 
292, beneath a lower guide roller 294, and across a support plate member 
296 extending between and supported by the support arm structures 288. As 
it leftwardly exits the support plate member 296, the web 68 passes over a 
guide roller 298 and wraps around a drive roller 300 which advances the 
web 68 a predetermined length into a vertically opposed pair of drive 
rollers 302, 304 that operate to pull each sheared-off tie element 62 from 
a shearing knife 310. 
As the web 68 is drawn leftwardly along the upper side surface of the 
support plate member 296, a vertically reciprocating heating die 306, 
carried by the left support arm structure 288 and positioned above the 
support plate member 296, forms the weld lines 78 (FIG. 7) on 
longitudinally spaced apart sections of the leftwardly moving tie element 
web. As the web, with the weld lines 78 thereon, leftwardly exits the 
guide roller 300, it passes between the base and reciprocating knife 
portions 308 and 310 of a vertically reciprocating slitting knife 
mechanism 312. Operation of the vertically reciprocating knife 31 
transversely separates the individual tie elements 62 from the leftwardly 
moving web 68. As each individual tie element 62 exits the slitting 
mechanism 312 it is drivingly engaged by the drive rollers 302, 304 and 
moved leftwardly between a pinch roller 314 and the bottom side of a 
rotationally driven vacuum belt 316 positioned over the central drive 
roller 92. 
As illustrated in FIG. 10, clockwise rotation of the vacuum belt leftwardly 
transports the individual tie elements 62, and positions the leftmost tie 
element directly above the central drive roller 92 and the longitudinal 
section of the folded plastic film web 22 momentarily stopped thereon. 
With the leftmost tie element 62 stopped in this position, its inner end 
portion 62.sub.a extends forwardly beyond the font side edge of the vacuum 
belt and is positioned over the overhanging side edge portion 42.sub.a of 
the folded web 22 (FIG. 4), and its outer end portion 62.sub.b (which 
extends outwardly beyond the rear side edge of the vacuum belt) is 
positioned as illustrated in FIG. 5. 
To attach the leftmost tie element 62 to the particular individual bag 
stopped at the central drive roller 92, a pair of reciprocating heating 
dies 318 and 320 are mounted at the left ends of the support arm 
structures 288 and are respectively positioned over the outer and inner 
end portions of the leftmost tie element depicted in FIG. 10 which 
laterally extend beyond the opposite side edges of the vacuum belt. The 
heating die 318 is utilized to form the small circular dimples 80 (FIG. 7) 
on the outer end of the leftmost tie element 62, and the heating die 320 
is used to form the circular weld line 74, and the slit 76, on the inner 
end portion of the tie element. 
It will be appreciated that the rate of advancement of the individual tie 
elements formed from the leftwardly advancing web 68 in the tie element 
attachment portion 60.sub.b of the machine 60 is appropriately and 
intermittently sequenced relative to the sequence and speed of folded web 
advancement at the central drive roller 92. This sequencing is 
conveniently achieved using the microprocessor portion 198 of the control 
system 192 schematically depicted in FIG. 12. The microprocessor, in 
response to the tie element attachment output signal 226, transmits output 
signals 322, 324, 326, 328 and 330. Output signal 322 is indicative of the 
stoppage of the stepper motor 102, output signal 324 is indicative of the 
reciprocating dies 318, 320 being in their downward position, output 
signal 326 is indicative of such dies being in their upward position, 
output signal 328 operates the slitter 312, and output signal 330 advances 
the tie element web 68 through its next increment. These signals, of 
course, are appropriately interrelated to position signals associated with 
the web handling portion of the tie element attachment machine. 
As previously mentioned, and as schematically illustrated in FIG. 1, the 
tie element attachment portion 60.sub.b of the machine 60 is pivotable 
between a lowered, solid line operating position and a raised, dotted line 
access position. According to a feature of the present invention, 
appropriate control means 331 (FIG. 1) are provided to monitor the 
cooperative operation of the machine portions 60a and 60b when the tie 
element attachment portion 60.sub.b is in its lowered position and the bag 
web 22 is being leftwardly conveyed as previously described. In the event 
of a machine malfunction, such as a jamming of the machine portion 
60.sub.b, or a deviation in one or both of the bag web loop lengths from 
its maximum or minimum permissible length, the schematically depicted 
control means 331 are operative to upwardly pivot the machine portion 
60.sub.b (by operating suitable drive means not illustrated) to its access 
position while the bag web 22 continues to be produced and run through the 
machine 60. 
To effect this automatic upward pivoting of the machine portion 60.sub.b, 
appropriate condition signals 331.sub.a, 331.sub.b are transmitted to 
control means 331 from the microprocessor 198, the signal 331.sub.a being 
indicative of sensed operating condition of the machine portion 60.sub.a, 
and the signal 331.sub.b being indicative of a sensed operating condition 
of the machine portion 60.sub.b. If either signal 331.sub.a or 331.sub.b 
is indicative of a malfunction of its associated machine portion the 
control means 331 output a signal 331.sub.c to energize the aforementioned 
drive means which, in turn, upwardly pivot the machine portion 60.sub.b. 
The control means 331 may, at this time, also transmit an output signal 
331.sub.d used to energize an audible alarm (not illustrated). 
The overall operation of the machine 60 is adjusted and controlled by the 
main control panel 332 (FIG. 15) which, as seen in FIG. 9, is positioned 
on the right end of the support frame structure 86. The panel 332 includes 
heating temperature controls 334, 336 for the tie element weld lines 74 
and 78, and the dimples 80, and a heat seal time control 338 for these 
areas. A length adjustment dial structure 340 is provided for inputting to 
the machine the length of the individual bags being driven therethrough. 
To monitor the number of bags which have passed through the machine 60, 
appropriate cumulative counters 342, 344 are also provided. Finally, 
appropriate on-off switch controls 346, 348, 350 are respectively provided 
to control the power, tie element attachment, and transport functions of 
the tie element attachment machine. 
The foregoing detailed description is to be clearly understood as being 
given by way of illustration and example only, the spirit and scope of the 
present invention being limited solely by the appended claims.