Note: Descriptions are shown in the official language in which they were submitted.
218~149
wos-lls2ss r~l~m~ ~ ;79
Flexible Bag and Method of Makin~3 and Attachin~ a Tie
CROSS-RFFFRF.~l~F TO RF3 ATF.T) APPLT~TION
5 This application is a ~ " ,;; ' ;. " .-in-part of q~ll j~ qTinn Serial No.
389,757, August 4, 1989, U.S. Patent No. 5,188,580, which was a ~
in-part of Serial No. 117,209, November 4, 1987, U.S. Patent No. 4,854,735,
entitled "Plastic Film Bag with Integral Plastic Film Tie Element, and Associated
r~l;~Li~.... Methods" which is hereby ihl~ ' by reference herein.
BAt~T~('TR-~UND OF I~TF. rNVFl~TION
The present invention relates generally to the r of
plastic film bags and, in a preferred ' tnereof, more IJ~uL;~ uly
provides apparatus and methods for attaching to the bags pTastic film tie elements
which, as disclosed in my copending U.S. q,~1i~qtir~n serial no. 117,209, may
be tied around the open tops of the bags to tightly dose them.
In the ' .; of plastic film bags it is common practice to
form them, by ~ ~1 extruding plastic film in tubul_r form, flattening the
film tube to form a double layer "web", forming lateral weld ITines _nd
.r~,laLioll lines across the web to define the individual bags which may be
'~ , separated from one another at the p~rul.~l;ol~ lines, and then
laterally folding the web prior to packaging of the bags. The laterally folded film
web is then typic~ly delivered to a packaging station spaced apart from the bag
.
218I14
W0 95/19259 ~3 . r~ 179
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
5 paclcaging station, it is ~esirable to '~, stop the web at each bag during
the p r. ,. ., ~ ~ of a particular, .,I; r~ operation thereon - for example, the
attachment of a plastic film tie element disclosed in U.S. application Serial No.
17,209 ill~,UI~ ' ' by reference herein.
There al-e presently two methods for effecting this necessary
y stoppage of the web as each individual bag passes the, -RI.r;. -l;",.
station - neither of which is wholly ~ali;~ra~ y. First, both the bag forming
station output feed portion and the packaging station input drive may be
l.,1.., 'y operated in a start-stop fashion to ~Iy advance and then
stop the entire folded film web section extending between these two operating
15 stations. While this is a quite logical app~oach, it - Iy slows the overaU
bag production rate - a rate which must be kept as high as possible for
,ulurllalJili~y purposes.
Second, a rather comple~c, high mass, shiftable multi-roller
structure may be utilized to erlgage and '~, stop a portion of the folded
20 plastic film web between the bag forming station and the winder without slowing
or U~ the output and input web travel at these portions of the ove~all bag
forrning apparatus. ~[owever, this high mass roller structure must be very
rapidly shifted back andl forth to stop each individual bag received thereby during
the high speed bag forming process. Because of the rapidity with which the
~wo gSrl92sg 2 1 8 1 1 ~ ~ P(~ J,S'~ 179
multi-}oller structure must be '!r 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 adjustcd, these high shift
forces can easily tear the traveling film web at one of its ~.r.,.,l;.. Iines,
creating significant down time and waste in the bag r ' g process.
In view of the foregoing, it can be seen that improved apparatus
and methods for r~--m~n~Drily stopping each individual bag in the film web,
during its movement between the bag forming station and the winder, are needed.
It is accu~ an object of the present invention to provide such improved
apparatus, methods and bag structures having integral tie elements.
SUMMA.RY OF 'i~F. INVEN~ON
In carrying out principles of the present invention, in 2 ~
with a preferred ,...l.u~l' .... ~ thereof, an in-line closure tie element attachment
machine is positioned between a plastic film bag forming station, which
l~, produces a folded plastic film web divided into imdividual bags by
y spaced 1 r '- Iines, and a winder ' 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
20 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
and a central drive roller positioned between the inlet and outlet drive
rollers in a laterally spaced, parallel ' therewith.
Positioned beneath these three drive rollers are first and second
21 8 1 1 ~ 9j
WO 95/19259 ~ F~,l/.s.,..'~ 179
;r~ L va~uum bins, the first vacuum bin having an open upper end
positioned generally between the inlet and central drive rollers, and the secondvacuum bin having an open upper end positioned generally between the central
and outlet drive rollers. Vacuum pump means are connected to lower end
S portions of the bins fo~- creating vacuums 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 ~ ly c~ , to the linear web output and intake speeds of
the bag forming station and tlle winder ' However, the control means
1~, operate the central drive roller, preferably via a stepper motor, in
a manner such that the central drive roller is sequentially stopped, ~ ' ' to
a rotational drive speed higher than those of the inlet and outlet rollers,
~1PrPlP~^~ and then stopped again.
Each sequential stop-t~stop drive cycle of the stepper motor-
driven central roller 1 ~ , advances the portion of the web engaged by
such roller a I I ' distance so that Wll~_r ~ sections
of the individual bags, to which fle~ible tie elements are to be attached, are
~u~o~ ,ly and '~, sto,oped on the central driw 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 ~ positioned between
the inlet and central drive rollers, and between the central and outlet driver
W095/19259 ~1811~ PCT/USg5~00~79
rollers. The vacuums formed in the first and second vacuum bins exert yielding,
duw~ directed forces on the first and second slack web portions, created
by air pressure ~ across the web portions, pulling web portions
du.... ~-lly into the bins and positively, but rather gently, holding them in
5 du..l.w~dly ectending first and second web loop, 5~
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 c,~,~c ~ Ionger than the second web loop. During tie element
attachment to the 1~, stopped bag portion of the web, the first web loop
10 lengthens, and the second web loop shortens, within their respective vacuum bins
as the inlet and outlet drive ro'~lers continue to be driven at constant rotational
speeds, the outlet roller talcing slack out of the second loop while the inlet roller
adds slack to the second web loop. The slac c talce-up capabi'ity provided by the
t~l second loop prevents the still-running outlet drive roller from
1', imposing tension force on the web sufficient to tedr it at one of its ~ru~dliUII
iines positioned on the second loop. ~ , tne slack provided in the two
web loops permits sequentia' bag stoppage without a'ltering or ., _ the
, constant linear web output and intalce velocities at t'ae bag forming
station and the packaging station winder ' .~Li~"l~ "
20 a very high bag production rate may be
After its tie element is attached to the '~1 stopped bag,
the centra' drive roller is a ' 1, held at a constant elevated speed,
~i~,rl.."~rA and then re-stopped, as previously described, to stop the next
n~ih~ s71ly successive bag thereon for tie element attachment thereto. This
W0 95~19259 21~ 19 r~ s ~ ~79
5~
~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 ori~inal length " ~ at the time the central drive roller
is stopped at tne end cf its drive cycle. The rapid take-up of the slack in the first
5 loop is achieved against the yielding, du~dly directed vacuum force thereon
so that the web is not torn at one of the L ' Imes in its first loop portion.
Additionally, this slack take-up and loop length 1; does not alter or
interrupt the constant velocity of the web entering and e~iting tne tie demcnt
attachment machine.
The control means may be adjusted to A ' for differentbag
lengtns being run through ~he machine, and the vacuum bins are provided with
movably adjustable front side walls to, for changes in the width of tne
particular folded plastic film web upon which the individusl bags are formed.
The lengtbs of the vertically oscillating web loops within the first
and second vacuum bins are _ '~, monitored by means of vertically
spaced series of l,l .. ~ . b 1' ' 1 l ;' beam i and associated receivers which
input loop positional i .r..., --;.... to the control means to permit ~I'L .
corrective action to be taken should either of the loops become too long or too
short during machine operation.
Additionally, the 1 ~- ' ' position of each successive bag
stopped on the cemlal drive roller is ~ , monitored by a unique
p~rul~Liull detectio~ 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 l' .r.. ~i.. detection system, in a prefe~red ~...I.,)~Ii,~.. .,l thereof,
wo 95/19259 2 18 1 1~ ~ F~ ,' 'C 1~9
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
5 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
lines.
The folded web portion a~ ua~ll;l.~, the central drive roller is
routed bet~-veen the electrode and the conductor so that the web ~ r...~';(. lines
10 ~u-,c~i,;vdy pass al~el,~h.~ll. 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 r r~ area,
thereby energizing an associated current sensor. r,~ Of the current
sensor causes it to transmit an output signal to a JlJlUl~U portion of the
15 control means indicating tne passage of another ~.r...,~;--. line past the
electrode. This r " is ~ , correlated to the rotational drive
of the central drive roller to ~ monitor the
orientation of each individual bag stopped thereon.
In the event that the individual bags begin to be l~ y
ll.. i~ ' relative to the central drive roller at which they '~
stopped (due, for example, to minor drive roller slippage), the , ~Ul
. 11y adjusts the rotation of the central drive roller to correct the
The tie element attachment portion of the machine is pivotally
WO 95/19259 21~1~ 4 ~ PCTlUS95/oo.l79
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
5 increment~lly advanced, above the inlet and central drive rollers and the folded
plastic film bag web, toward the winder m~ c~ As the tie element web
approaches the central drive roller a slitter knife i ~l~.y cuts it into the
irldividual flexible tie elements which are sequentially moved to positions directly
over the central drive roller, and the stopped 1" \z ,~ bag sections thereon,
by a vacuum belt.
The inner end of each tie element is then heat welded to a gusseted
side edge portion of its associated bag, adjacent the openable end thereof, by
means of a first l~;yl~ ~ heating die which also forms a slit tbrough 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 e~ctends 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 e~tended 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
,~ in a variety of manners, it is ~ ,"' ' in a preferred
~W09s/19259 218~ 1A9 ,~""~ .~, 179
of the present invention using a second IC~ JlU~t;ll~ heating die
which functions to form by both mPr~ l force and thermal ~I~ f ~ ., a
series of "dimples" in each outer tie element end which extend into cu.l~ r
formed in the underlying layer of plastic bag film. The interlock
5 between these dimples and bag film ~ keep tne tie elements from
flapping about during packaging of their associated bags, but later pem~it each
outer tie element end to be easily separated from its associated bag witnout
tearing a hole in the bag.
When a bag is ultimately detached from the laterally folded plastic
10 film web, the outer tie dement is simply pulled outwardly fror~ ind detached
from the bag. The tie element is then looped around ~he open bag end to form
a tightening loop ~h~ ' Finally, the now detached outer tie element end
is passed through the slit in tne inner tie element end and pulled to tighten the tie
element loop atound the open bag end and tightly close it. The slit length is
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 o~ the tie element loop around the bag.
In an l u.. t, a tie strip web is provided with a band of
adhesive covered with a release sheet. The tie element web is then severed
20 ~ ly and attached at one end to a side edge of the bag web. The bag is
closed by removing the release strip covet, gathering the top of the bag and
wrapping the adhesive-coated tie element around the gathered top of the bag onto
itself. In one variation, the adhesive is a IGlA~ adhesive without a release
cover over the adhesive. The adhesive is designed to have a low tack
. .
WO 9S/192S9 2 ~ 9 r~ 179
in contact with the bag web, but a higher tack ~ l ~ r~ wheD
wrapped around the bag in contact with itself. In another variation, the adhesive
may be applied in patches on opposite surfaces with or without a release cove}
such that when wrapped around the adhesive on one surface comes in contact
5 with the adhesive on another surface formiDg a bond.
-- The tie element attachment machine of the present invention may
be cu..~ / placed "in-line" in an e~isting plastic film bag forming system,
and the web handling portion of the macbine may be used to sequentially stop
spaced ~ sections of the ~, moving bag web for purposes
other than tie elemenl _ '
RRTFF ~E~t'RTPPlON OF TFTF. D~AWINGS
Fig. 1 is a simplified schematic side elevational view of a
cu~ ' in-line plastic film bag ~ ~ system in which a tie element
attachment machine of the present invention is operably imterposed to attach to
each of the individual bag portions of the removing plastic film web a flexible
plastic film tie dement which may be wrapped and cimched around the open bag
end to tightly close it;
Fig. lA is an eDlarged scale, ~ r~ 1 cross-
sectional view, taken along line lA-lA of Fig. 1, through a side edge-gusseted
plastic film web being produced by the system;
Fig. 2 is a top plaD view of the moving plastic film web, prior to
its entry into the tie element attachment machine, taken along line 2-2 of Fig. l;
Fig. 3 is a top plan view of the moving plastic film web, exiting
the tie element attachment machine, taken along line 3-3 of Fig. l;
WO 9~i/192~9 2 1 ~ 1 F~ )b,'' - ~79
Fig. 4 is an enlarged scale, hori~ontally ru~ ul~.l~l cross-
sectional view through the moving plastic film web, taken along line 4-4 of Fig
2, illustrating the 1~ manner in which it is laterally folded;
Fig. 4A is a ~;IU~7. !;~liulll view of a non-gusseted alternate
5 ~ of the u.~ .6i..6 right side edge portion of the plastic film web
depicted in Fig. 4;
Fig. S is an 1.1A~ of the circled area "S" in Fig. 3;
Fig. 6 is an CIIIAIO ' of the circled area "6" in Fig. S;
Fig. 6A is an enlarged sca'le partial cross-sectiona' view through
10 the film web, and the inner end of a flexible tie element, taken along line 6A-6A
of Fig. 6;
Fig. 7 is an; ' ~ of the circled area ~7" in Fig. S;
Fig. 7A is an enlarged scale partia'l ~u..~ ~L;u.~dl view through
a~ outer tie element end, a~ld an underlying bag web portion, taken along line
7A-7A of Fig. 7;
Fig. 8 is a ~..,~liv~ view of a portion of one of the plastic bags
and illustrates the manner in which its asso~iated tie element may be used to
tightly close the bag;
Fig. 9 is an enlarged sca'e, somewhat simpLified p~ ,~li~ view
20 of the tie element attachment machine;
- Fig. 10 is an en'larged scale pa~lial cross-sectional view through
the tie element attachment machine taken a'ong Line 10-lO of Fig. 9;
Figs. I1 and llA are schematic cross-sectional views taken
through the tie element attachment machime along ine 11-11 of Fig. 9, and
wo 95/19259 2 1 ~ ~ 1 4 ~ r~ .. ,r~ 79 !
12
sequentially illustrate the alter~at~ng~ ~novement of two slack plastic film webportions disposed wi~in a vacuum bin section of the machine;
Fig. 12 is a schematic control diagram illustrating the feedback
Ill;ClUylU~,~aVl control of inlet, outlet and central film web drive roller portions
of the tie element attachment machine;
Fig. 13 is an enlarged scale ~ ~Live view of a bag
perforation detection system portion of the tie element attachment machine;
Fig. 14 is a schematic ~.u.. ~liul.cl view through the perforation
detection system, taken generally along line 1~14 ûf Fig. 13, amd additiûnally
illustrates certain control circuitry associated therewith; and
Fig. 15 is a front side elevational view of a main control panel
portion of the tie element attachment machine;
Fig. 16 is a ~I~LiVt~ view of an improved tie element strip
having an adhesive and a removable release coated cover strip over the adhesive
shown affixed at one end to the side edge portion of a flattened plastic bag web;
Fig. 1'7 shows the tie element of Fig. 16 wrapped around the
gathered top of the plastic bag and par~ally overlapped to close the bag;
Fig. 18 is a ~ view of a variation of the improved
adhesive tie element strip having one end affixed to the side edge portion of a
2û flattened plastic bag web and having adhesive patches on opposite side surfaces
with removable release patches designed to bnng the adhesive patches together
' when the tie element is wrapped in the manner of Fig. 17;
Fig. 1, is a p~ ~liv~ view of a schematic process for applyimg
multiple bands of adhesive to a plastic web, drying the adhesive bands and
wo ssllstss 2 1 8 ~ 1 ~ 9 p "~ ~ ,,9
13
applying protective releasable cover strips;
Fig. 20 is a schematic showing the product of the process of Fig
19 being separated into multiple rolls of adhesively coated tie element web to be
used to make tie elements;
S Fig. 21 is a schematic partial cross-sectional view of a modified
form of the tie element attachment machme of Fig. 10 illustrating h .~ ly
severing individual adhesively coated tie elements from a roll of tie element web
shown in Fig. 20;
Fig. 22 is a ~~ iV~ view of another "~1;1; ~ of the
10 improved adhesive iie element strip of Fig. 16 with a ~ 1 adhesive
employed without a removable cover strip;
Fig. 23 is a ~l~ iVt~ view of a, ~ ;.,.. of the improved
adhesive tie element strip of Fig. 16 in which the releasable cover strip is
shortened at the outer end to expose a patch of adhesive.
DETATrrn nF~('RTPrlON
Srh~ ir~1ly illustrated in Fig. 1 is a plætic film bag forming
station 20 which, during operation thereof, outputs a laterally folded plastic film
web æ (see also Figs. 2 and 3) at a constant linear r gi~ ' ' speed Vl. The
bag forming station 20 includes a plastic extrusion die 24 which . '~,
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 iube to a flattened tube or "web" 32
(see also Fig. lA) 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
.
wo 95119259 2 1 ~ ~ 1 4 9 - P~ c- ~79 ~
14
defined by four layers of plastic fiiqn 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 ~ y depicted apparatus 38, as its name implies,
S sequentially perforrns three operations on the web 32 traversing the apparatus.
First, it forms on the web a l~ c;~ y 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 l~ncjtn~iir~lly 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 42a (containing the gusset 31) to
extend laterally beyond the balance of the laterally folded, flattened film tubewhich ultimately defines the laterally folded plastic film web 22. The number
of folds in the folded web æ are, of course, merely IC, ~ - a greater or
lesser number of folds could be forrned.
After the web 32 has been heat sealed along lines 40, and laterally
folded as just described to create the folded web æ, the apparatus 38 operates
to form on the folded web 22 a l~ih~ y spaced series of laterally extending
perforation lines 50 which extend completely across and through the laterally
folded, web æ. 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
~ WO 95119259 2 1~ 114 9 F~ 179
film web 22 exiting tbe apparatus 38 a 1, v ' ' 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
S along one of the ~ rulaLiu,~ 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 ~U~ iUllod winder 52, spaced apart in a leftward direction from
the bag forming station apparatus 38, at a constant linear speed V2 equal to thelinear output velocity Vl of the film web 22 from the bag forming station 20.
To provide tension control therefor, the folded web æ is passed beneath a
stationary roller 53, and over a pivotally mounted dancer roller 54 prior to beimg
drawn into the winder 52 wherein it is wound upon a suitable storage
roll (not il- 1)
Operably interposed between the bag forming station apparatus 38
and the winder ' 52 is a tie element attachment machine 'v;0 which, as
ly described, is utilized to secure to each of the imdividual bags B,
adjacent its openable end, a plastic film closure tie element 62 as illustrated in
2û Figs. 3 and 5 which are top plan views of the laterally folded plastic film web
æ as it exits the machine 60. Macbine v0 basically comprises a web handling
portion 60a, and a closure tie element attachment portion v0b which is mounted
atop the web handling portion 60a and is pivotable relative thereto between a
lowered operating position (shown in solid lines in Fig. 1) and a raised access
:
woss/ls2~s ~18~ ~49 r~ a~ 7s
16 ~.
position (shown in phantom in Fig 1). A schematic, ~ ~I; ri ~ of tie element
attachment machine 60 shown in Fig. 21 is employed to apply adhesive tie
element strips from a tie element web as will be described later.
As will be seen, the web handling portion 60a operates to engage
S and leftwardly drive a 1 ~gi~ y central portion of the folded web 22,
positioned between the apparatus 38 and the winder ~I~ r~l 52, and to
sequentially and mn~nt~rily stop each of the individual bags B and stationarily
position a ~ section thereof for attachment thereto of the bag's
associated closure tie element 62. I~ Iy~ this ;--t . ~.. '1. ..1 stoppage of each
of the individual bags moving from the apparatus 38 to the winder l~ ;e~
52 is effected without ;~ .;dWy altering the web output and intake linear
velocities Vl and V2 and without imposing upon the I gi~ moving web
22 ~ high l~ g ' ' 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
Iy ~ ' ' 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 I~ ' ' 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 wi~h reference to Figs. 1 and 5-8. The .q..~
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
21~ 9
wogS/19259 - - - r~ 79
17
ih~ axis with a heated slitting knife or wire. The lateral flahened 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
S knife or wire. It will be ~.y~ ' 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
60b of the machine 60 and is laterally cut into elongated ships that define the tie
elements 62 which are secured to the individual bags B. Other improved forms
of elongated adhesively coated tie element shiips and methods of rnaking and
applying them are shown in Figs. 16-23. They will be described later.
As best seen in Figs. 5-7, each of the tie elements 62 has an inner
end portion 62a which includes a portion of the folded side edge 70 of the tie
element web 68 and overlies the u.. ' _ _ side edge portion 42a of the
laterally folded plastic film web 22. The tie element inner end portion 62a is
firmly secured to the web side edge portion 42a 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 42a of the folded web 22.
A l ~ extending slit 76 is formed through the tie element
20 end portion 62a, and the underlying web side edge portion 42a, and is positioned
within the circular heat weld 74. From its secured inner end portion 62a, the tie
element 62 extends 1. . ~ y across the upper side surface of the folded web
22, with the tie element 62 being parallel to and adjacent the ~r~ line 50
that defines the openable end of the individual bag with which the particular tie
WO 9!i/192~i9 2 1 8 1 14 ~ r~ 1/U~,5.'~ ~ ~79
18
dement is associated.
The anchoring of the ,in~ner 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 illt~l~ between e~ch tie
S 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 u.. ' , ~ 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)1 to the two film layers of the modified side edge portion
42b.
Each of the tie elements 62 also has an outer end portion 62b,
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 I 1~, strong due to the fact that
it was formed by a he~ted slitting knife or wire. A' " ~'~" a pair of laterally
extending heat weld lines 78 are formed on the tie element 62 adjacent its outer
end, in a manner 1 'y described, to more firmly intersecure the two
plastic film layers of ~he tie element in that region.
To releasably restrain the tie element 62 in place across the top
side of the laterally Eolded plastic film web 22, so that the web 22 and the
attached tie elements 62 may be smoothly drawn into the winder ' 52,
five small dimples 80 (see Figs. 7 and 7A) are formed in the outer tie element
end 62b and are received in C.~. IL ~ .--- 80a in the plastic web
WO 95119259 21~ 9 PCTIUS95/OW79
19
film layer beneath the tie element. As ~U~S.~U~ y described, a heated die is
used to form these dimples and d~l~ iullS which are formed by a ~
of m~h^~ forceand ~h ~ ` distortion without~ ~;d,ly heat welding
the tie element end 62b to its associated bag. Accordingly, tbe tie element end
62b can later be pulled apart from the bag without tearing the bag. To use a tieelement 62 to tie offand 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 itis releasably restrained by the ' ' ~ dimples 80 and .1~ 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, tbe tie element 62 may then be used to
tightly close and se 1 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 at62c, at its juncture with the slit, thereby ' 'ly inhibiting loosening of the
bag-closing tie element loop 84.
The illustrated closure tie element 62 is merely -r ' ' vt~ 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 alternateclosure tie element c-- r~ are illustrated and described in U.S.
application Serial No. 117,209 which has be~n ill~.Ul~ ' ' herein by reference.
WO 95/19259 2 ~ 8 ~ 179 ~
Adhesively coated forms of tie element web and strips are disclosed in Figs. 16-23.
Referring now to Figs. ~ and 9, the tie element attachment
machine 60 includes a generally l~ ~ ' support frame structure 86 which is
S floor ! r ~1~ on îour vertically adjustable support feet 88 positioned at the
corners of the support frame structure. The web handling portion 60a of the
machine 60 is carried by a front side portion of the frame structure 86 and
includes three drive roller members - an imlet 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 samehorizontal plane.
The three drive rollers I ~ , e~ctend 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. AsC, h. .".~;...lly depicted in Fig. 12, the roller 90 is driven in a ~
direction by a motor 100, roller 92 is driven in a, ' ' ;,~ direction by
a stepper motor 102, and roller 94 is driven in a . .,I~L~;,~ direction by
a motor 104.
Supported by a front side portion of tne support frame structure
~6 directly beneath tlle 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 ' '~, to the left of bin 106. The vacuum bins 106, 108 have
generally ~ open top ends 110 and 112, bottom walls
21~ 9 r~ ,s~~17s
J ~ 21
114 and 116, a common central side wall 118, outer right and left side waUs 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
5 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 tbe left vacuum bin 108 and
has an inlet 134. The inner ends of a pair of fle~;ible vacuum hoses 136 and 138
are connected to the inlet 134, and the outer ends of the hoses 136, 138 are
ly connected to the bottom vacuum bin walls 114, 116 and
with the interiors of the bins 106, 108. The interiors of the
vacuum bins 106, 108 ~ with one anotner via a transfer passage 140
formed tbrough a lower end portion of the common central bin waU 118 and
r " ' ,, to generally equalize the vacwms drawn in the t vo bins.
Also for purposes later desaibed, a verticaUy spaced series of five
beam i ~ units 142, 144, 146, 148 and 150 are mounted
on the right bin side wall 120 and are adapted to leftwardly transmit 1
beams 152 across the interior of vacuum bin 106 for receipt by a vertically
20 spaced series of beam receiving members 142a- lSOa mounted on the central bin
wall 118. In a similar fashion, a vertically spaced series of L ' ' beam
154, 156, 158, 160 and 162 are mounted on the left bin side wall
122 and are operative to l;6~l~wa~dly transmit L ' ' ' ' - beams 164 across the
interior of the left vacuum bin 108 for receipt by a vertically spaced series of
.
wogsllg~9 2 ~11 4 3 PCT/US9~/00179 ~
22
beam receiving units 154a-162a.
Referring now to Figs. 9 and 11, the web handling portion 60a of
~he tie element attachment machine 60 also includeS i`- pair of pinch rollers 166
amd 168 which are rotationally carried at their outer ends by arm members 170,
'172. The inner ends 3f the arm members 170, 172 are pivotally carried by a
pair of upright support plate st~uctures 174 and 176 which project upwardly fromleft end sections of the support frame portions 96, 98. As illustrated, the arm
members 170, 172 are J~ udly pivotable to ~ ly position the pinch
rollers 166, 168 agaillst 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 1~0 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 ~....~udly 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 e~tended through a
CUII~L '' 1 web gui~e apparatus 186, secured to a right end portion of the
support frame structure 86, which functions to: 'Iy maintain proper
lateral alignment of ~he web during operation of the overall system. Upon
leftwardly exiting the web guide apparatus 186, the web 22 ~ passes
beneath a guide roller 188, between the drive amd pinch roller sets 90 and 180,
92 amd 168, and 94 a~d 166, beneath a guide roller 190, beneath the stationary
rolle} 53, and over the pivotally mounted dancer roller 54 and upwardly into thewinder ' 52. Utilizing the ~ . 1y described control system 192
~ wogS/19259 23 21~ P~ c ,,9
- (Fig. 12), start-up of the web handling portion 60a 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
S rollers 90, 92 and 94, amd passing the web beneath roller 190 and o~~ ly
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 llli~ lu~Jlc~la~l 198 (Fig.
12), initiates the operation of rollers 90 and 94 at rotational speeds wll. r
to the ]ine~r web velocity Vl.
When it is desired to attach tie elements to tne web æ, an operator
moves the switch 331 from its "LINE" position to its "RUN" position. This
signals the Illi~.lUIJIU~aa~J~ 198 to energize the vacuum pump 132 (Fig. 9) and
slow the rotation ûf roller 94 via an output signal 208 h ' to its speed
wntroller 210. The slowing of roller 94 causes the web æ to be pulled
15 du~Jly into the vacuum bin 106. In a manner ' , '.~, described, when
web æ du....w~.-lly reaches a I " ' level witbin bin 106, the
UIJlU~aaOl 198 transmits am output signal 200 to speed wntroller 202 (Fig.
12) to rotationally "step" the roller 92 at a rotational velocity greater than the
linear velocity V1, permittmg the web æ to be vacuum-drawn ~' ..A.w~udly into
bin 108 into a looped . S, 204 until, in a maumer ' ~
described, the ,UllC I ~ ~ web loop 194 in bin lOo is shortened and the loops
194 and 204 are in their relative length ,~ , illust~ated in Fig. 11. In
such length tbe loop 204 is ~ , longer than loop 194.
After this initial length ' between the web loops 194,
.. .. . . . .. . .
2 1 ~
WO gS/19259 ! ~ r~ c
24
204 is achieved, the ~ lul,l~ol 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 ,,~ Upon attainment of this condition, the switch
331 is moved to its "RUN" position which, via the ~ u~ ol 198, lowers
the tie element porlion 60b 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
~;uullt~ wiac, variable rotational speed ~ to the linear web
output speed V1 so that the wcb tal~up speed of the roller 90 is equal to the
linear web output speed from the apparatus 38. The above~escribed slowing of
roller 94 for[ns 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 slaclc web portion du.. dly into bin 106 and gently holds it in the
illustrated, du.... ~diy loopecd ~ I,,," 194 (Fig. 11). As the roller 90
continues to rotate, the vertical length of the web loop 194 ~-----d~llr
increases.
The increasing length of the web loop 194 is '!1
monitored by the l ' : ' beam receivers 142a-lSOa supported on the central
bin wall 118. It can be seen in Fig. 11 that as the web loop 194 e~tends further
du .. I.~udly within the bin 106 it sequentially blocks lu ....w~udly successive ones
of the ~ t~ l.. ~ beams 152. When the lower end of the loop web 194
Owoss/ls2ss 25 218~14~ r~ m c l79
duwv~lw~ly reaches a ~ ' ver~ical level within the bin 106, a
vc~ signal 196 (Fig. 12) is; ' from the receivers 142a-150a to
a l..k,l~J~JlU~ VI 19g, the signal 196 indicating that the vertical length of the web
loop 194 has reached its desired magnitude.
Upon re~eiving the signal 196, indicating that the web loop 194
has reached its desired initial length within the bin 106, the II.i~,lU~JIU~i~lVI 198
~u~ ly 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 incre~ses 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 secorld du .. Ilwal-lly extending web loop 204. When the bottom
end of the web loop 204 is properly positioned within bin 108 (see Fig. 11), the
15 ~ receivers transmit through the , U~,vl 198 a ~
signal 206 indicative of the fact that the left web loop 204 has now reached its
desired initial vertical length.
Mi. .,~..1,.. -`-.. 198 then 1~ -r ~,ly transmits am output signal
208 to a speed controvller 210 which operates the motor 104 to initiate a change
20 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
ænsor 212 that monitors the rotational speed of a smaU gear member 214 secured
to the front end of the inlet drive roller 90 for rotational therewith. Speed sensor
212 ~vll.;~ly transmits to the U~JlUC~Vl 198 a rotational speed-indicative
21~ 9
WO 9~/192!i9 - ` P~ S~ 79
26
output signal 216 which, in a feed~ack manner, is operative to adjust the outputsignal 208 to the speed controller 210, to thereby equalize the rotational speeds-
of the inlet and outlet ~rive 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 mainained in their length ,~l :;""~ , illustrated in Fig. 11
during the start-up phase of machine operation.
The IllI~,lU~lU~i.lJI 198, and the speed controllers 202 and 210,
are c~ , positioned within a rear side portion of the support frame
structure 86 (Fig. 9) along with various other cantrol, ll generally
indicated by the refererlce numeral 218. After the previously described start-upprocedure has been ~".~ ,.~ the web handling position 60a of the machine
60 is converted to its na,rmal operating mode by moving switch 331 to its "RUN"
position. In this operat~ng mode, the inlet and outlet drive rollers 90, 94 are still
rotated at constant and essentially identical speeds, but the central drive roller is
lS sequentially started and stopped to ~ and stationarily position
L,ir " I sections of each individual bag B, adjacent its perforation line 50 that
defines its openable ~nd, to ready such l~ gjh~ l bag sections for the
attachment thereto of the tie elements 62, or the tie elements shown in Figs. 16-
23, in a manner ' , '~1 described.
Quite '~" this sequential stoppage of each individual bag
B at the central drive roller 92 is P " ' ' without ~ ly altering the
const~nt output and intake velacities V1 and V2 of the l".,~ =lly moving
folded plastic film web 22 as it approaches arld e~its the tie element attachment
machine 60. Additionally, as will be seen, due to the unique formation of the
WO 95/19259 2 1 8 1 1 ~ 9 P~ 179
27
web loops 194 and 204 such individual bag stoppage is effectcd without imposing
upon the web 22 ~ 1 tension forces which might otherwise
te~r the ;eb at one of its ~rUl~liOI~ lines 50. The unique a l-;~ ~, of these
two very desirable results will now be described in, with Figs. 11 and
S llA.
In Fig. llA, the central drive roller 92 has been stopped, during
the continuing rotation of the inlet and outlet drive rollers 90 and 94, to thereby
~r~l~torjly hold the bag portion Bl thereon with the openable end perforation
line SOb of the bag Bl being ~' ~w~ldly adjacent the central drive roller 92, and
10 the opposite end pelrul~iull line SOa of the bag Bl being positioned upon the
web loop 204 being vacuum-drawn du.. ,cu-lly into the bin 108 through its open
upper end 112. The l.~,n~ l section of the stopped bag B1 positioned atop
the now stationary central drive roller 92 . ' to the I ~ ' ' section
of such bag to which its closure tie element, such as element 62 will be affi~ced.
During its y 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 ~ ly
indicated by the arrows æû and 2æ in Fig. llA. The left web loop 204 is
shortened against the d~ woldly directed vacuum force imposed thereon by the
vacuum pump 132. Accordingly, the tension force exertcd on the web loop 204
by the ,. '~, rotating outlet drive roller 94 in ' to tear any of
wo ss/l s2ss 2 1 8 1 1 4 9 F ~ ~ . , ,9
the web perforation lines disposed wi~}un th~ lefl vacuum bin 108 - all the outlet
drive roller 94 does during this period in which the central drive roller 92 is
'~, stopped, is take up the slack in the left web loop 204.
After its tie element 62 is secured to the Iy stopped bag
Bl, as monitored by an ~ .ul sensor æ4 (Fig. 12), the sensor 224
transmits an-output sig~al 226 to the u~lu~Daul 198 indicating that the tie
dement has been attached. The roller 92 is not c ~ i to rotate until
photocell 150 is covered by web loop 194, at which time the output signal 196
is i ' to Illi~ lUU,.~aVl 198. When the signal 196 is received by the
0 ~llil,lUylVC.,.. aVl, the u~lu~ , 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 . ~ started and rotationally P- ' ' to
. ' ' Y;~ rotational speed higher than the speeds of the inlet and outlet
drive rollers 90 and 94, maintained at this elevated speed for a
1~ time period, ~ ' I, 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
dement to the bag Bl, the right web loop 194 has been rc 1~ ~ and the
left web loop 204 ., ' ~..~, to their original lengths as depicted in Fig. 11.
20 Additionally, the next bag B2 has been stopped at the central drive roller 92,
with the openable and perforation line 50c of bag B2 positioned ~' woldly
adjacent the roller 92, and the opposite perfûration line 50b being nûw positioned
within the left vacuum bin 108.
After Ws stoppage of the central drive roller 92, which readies the
_ . _ , . . . . . . _ _ _
21811~
w0 sslls2ss ~ 79
29
bag B2 for the attachment of its tie element thereto, the web loops 194, 204
again begin to l~ iV~y lengthen and shorten as illustrated in Fig. llA. The
elevated speed level of the central drive roller 92, which shortens the web loop
- 194, does not implose, ' ~ , high 1 ~i~ " ' tension force on the loop 194,
5 since the roller 92 merely takes the slack out of the previously lengthened loop
194 against the yielding, du.... ~ly 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
u.. ~ the web æ or at",l~;~l~ altering the linear output and intake
speeds V1 and V2 of the web.
It will be ~rP ' that the U~JIU~i~JI 198 may be easily
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 centlal drive roller 92. The roller 92
sequentiaUy 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 ~ ' ' to essentially equalize the lengths of the web loops 194, 204 each
20 time the central drive roller is stopped.
In addition to precisely controUing each web ~lv length
of the roller 92, it is also important to insure that as each individual bag is
stop~ed 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
W095/19259 21811~9 F.l/O..,_. ~79
element is properly posi~oned on its associated bag. In the present invention,
this is achieved by the use of a specially designed perforation detection system230 which is illustrated in Figs. 11, 1 lA, 13 and 'I4.
The perforation detection isystem 230 includes a high voltage
electrode member encased in an insulation tube 232 which is mounted on &e
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 tlle 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 e~tending forwardly through the bin waUopening 238 rests upon and is supported by a horizontally extending tab porlion
246 of the rear side bin wall 124, and the left or discharge end 232a of the
electrode 232 is positioned slightly li~ Wald;,~' of the central bin wall 118.
Directly to the left of the inner electrode end 232a is a circular
opening 248 formed in the central bin wall 118. As cross-sectionally illustratedin Fig. 14, a cylindrical insulator member 250 has a boss portion 252 positionedwithin the bin waU opening 248, and a grounded cylindrical Inetal conductor
W095/19259 31 21811~9 F~ 179
member 254 extends coa~ially through the insulator member 250, the e~posed
right end of the conductor member 254 facing the inner end 232a of the electrode
232.
As illustrated in Figs. 11 and 14, a left side por~ion 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 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 r r... ~ ;~ ", 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 ~ u.~ ly transmits a ~ output signal 262 to the
llfi.,lUIJlU~i~Ul 198 (see Fig. 12). In this manner, a precise ~ of the
position of the openable end perforation line of each of the individual bags is
20 achieved so that when each individual bag is stopped at the central drive roller
92, the ~ " ' 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
21~1149
WO 9~/192~9 , . ~ C ~ ~79
at the central drive roller (such deYiation being caused for e~ample, by roller
slippage) the IIUClvlJIuCCoovi 198: 'Iy~f~ctions to adjust the signal 200
being transmitted to the speed controller 202 to 'y increase or decrease
the, ~,lo~w;O~, rotational steps of tbe roller 92 to readjust the stopped bag
S position on the central drive roller 92, and , ~ , adjust the signal 200
to increase or decrease the total number of rotational "steps" imparted to the
central drive roller 92 during one start-stop rotational cycle thereof, thereby
properly readjusting tbe ll nL ' I orientation of each indiYidual bag as it is
stopped at the central d1ive roller 92.
Normally, the rotational speeds of the inlet and outlet dlive rollers
90, 94 are the same. ~Iowever, 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 coYered by the loop 204), the
II~;Clu~luu~vl iS signaled and l~-r ._1~ causes the controller 210 to
increase the rotational speed of roller 94. In a similar fashion, when
web loop 204 becomes too short (such as, for e~ample, when photocells 156 and
158 are uncoYered), an err ~ signal is sent to the UIJlU~oUl which,
in turn, temporarily slows the rotational speed of roller 94.
The pivo[al mounting of the electrode 232 on the L,shaped support
arm 236 funceions to prevent ehe web 22 from being tom at one of its perforationlines 50 in the event that the right web loop 194 is shoreened to an extent that its
lower end contacts the ~uter end 234 of the support arm 236. In the evene that
this occurs, the web merely pivots the support arm 236 rearwardly to its stowed
2181149
W09S/192S9 r~ 79
33
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 c ; with Fig. 12 is,
of course, adjustable to . , - for different bag lengths being driven through
5 the web handling portion 60a of the tie element attachment machine 60, the bag
length being the distance between se~uentially adjacent pair of ~lruld~.l ]ines
50. The web handling portion 60a may also be easily adjusted to 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
amd 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 i' ' l~, receive elongated e~cternally 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
20 provided with resilient seal members 276 which slidingly engage the opposite left
and right side waUs of each bin.
Sprocket members 278, 280 are ~ ~ secured to the upper
and lower nut members 268 and 270, and are drivingly - ' by suitable
chains 282. The upper nut members 268 have secured thereto suitable
W095/19259 218~149 E~,l/U' ~'C-~79
34
adjustment knobs 284 which may be rotated to effect forvard or rearward
movement of their associated front bin walls. For exampIe, as viewed in Fig.
9, clockwise rotation of one of the adiustmént knobs 284 effects forward
movement of its associatc-d front bin waU, while . ;~ rotation of the
S adjustment knob causes rearward movement of tne front bin wall. In this
manner, front-to-rear width adjustment of the t vo 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 llandling apparatus oOa just described is ~ ,ul~ly well
suited to its illustrated use in handling the folded plastic film web æ used in the
in-line production of plastic bags in which it is necessary to 1~, stop
lly spaced apart sections of the . ~.~, moving web to secure
flexible tie elements to the stopped web sections. EIowever, it will be readily
~ ' that the unique structure and cperation of the weo handling apparatus
would also be quite useful for the ~ . r.... -- ~ of operations other than tie
element attachment - for example, in printing, attachment of au~iliary
of other types, arld the like.
Tu}ning now to Figs. 9, 10 and 21, tne tie element attachment
portion oOb of the machine oO will be described in detail. Common portions of
the schematic .... ~1.1;. -I l..., of Fig. 21 will be indicated by the use of prime marks
over the same numerical items. Some parts of Fig. 10 have obviously been
dropped from Fig. 21 as not necessary to the adhesive coated tie element strip
i
WO 95/19259 21811 ~ 9 F~.IIIJ., '~ 179
shown in Figs. 16, 18, 22 and 23 and/or are CUII~..JUIIal. Most notably the first
heat sealing device 306, support plate 296 and associated rollers are not
necessarily ne~ded. The support spindle 66, 66' of the tie element supply roll
64, 641 is rotationally supported on the upper ends of a pair of upright supportbars 286 extending upwardly from the support brackets 182, 184 positioned at
a right front corner portion of the support frame structure 86 as 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, 641 the support bars 286, and the support arm
structures 288 may be pivoted between the solid line, lowered operating positionof the tie element attachment portion 60b and its dotted line raised access position
~ly depicted in Fig. 1.
As best seen in Figs. 10, 21, the tie element web 68, 681 extends
d~ udly from the supply roll 64 and is passed under a dancer roller 291,
2911 which is pivotaUy carried on support arms 292 secured at their irmer ends
to the brackets 182 and 814. The web 68, 681 then passes upwardly around an
upper guide roller 292, 2921 beneath a lower guide roller 294, 2941 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 68,681 passes over a guide roller 298 and wraps around a drive roller 300 which
advances the web 68, 681 a l ' ' length into a verticaUy opposed pair
of drive rollers 302, 3021, 304, 3041 that operate to pull each sheared-off tie
element 62, 621 from a shearing knife 310. (Drive rollers omitted in Fig. 21)
21811~9
WO 9~i/19259 ~ 79
36
As the web 68"68' iS~d~awn leftwardly along the upper side
;; .. ~ .
surface of the support plate member 296, a Yeriically ~ u~Lill~ heating die
306, ca~ried by the left support arm structure 288 and positioned above the
support plate member 296, may form the weld lines 78 (Flg. n on 1....~ ly
spaced apart sections of the leftwardly moving tie element web 62. As the web
68, with the weld lines 78 thereon or the web 68' leftwardly exits the guide roller
300, it passes between the base alid lv~ ,lu~Li.~ knife portions 308, 308' and
310, 310' of a vertically lc~ilJIu~L..~, slitiing hiife m~~ r~ 312, 312'.
Operation of the vertic~lly lC~ lU~,4Lllg knife 310, 310~ ,ly separates
the individual tie elements 62, 62' from the leftwardly moving web 68, 681. As
each individual tie element 62, 621 exits the siitting 312, 3121 it is
drivingly engaged by the drive rollers 302, 302', 304, 3041 and moved leftwardly
between a pinch roller 314, 314' and the bottom side of a rotationally driven
vacuum belt 316, 316' positioned over the ceni~al drive roller 92, 92'.
As illustrated in Fig. 10, clockwise rotation of the vacuum belt
leftwardly transports the individual tie elements 62, 621 and positions the leftmost
tie element directly above the central drive roller 92, 92' and the 1-- 6~
section of the folded piastic film web æ ~ stopped thereon. With the
leftmost tie element 62, 62' stopped in t}iis position, its inner end portion 62a,
62al extends forwardly beyond the front side edge of the vacuum belt and is
positioned over the U.~ side edge portion 42a of the folded web 22 (Fig.
4j, and iis outer end portion 62b, 62b' (which e~tends outwardly beyond the rear
side edge of the vacuum belt) is positioned as illustrated in Fig. 5.
To attacl1 the leftmost tie element 62, 62~ to ihe particular
W095/19259 21811A9 r~ J.,J~ 179
37
individual bag stopped at the central drive roUer 92, a pair of lec;~lu~aLillg
heating dies 318 and 320, 320' are mounted at the left ends of the support arm-
structures 288 and are I~D~IiV~1Y positioned over the outer and inner end
portions of tne leftmost tie element depicted in Fig. 10 which lateraUy e~tend
5 beyond the opposite side edges of the vacuum belt. The heating die 318 may be
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, 320' is used to form the circular
weld line 74, or an oval weld line 74' and if desired the slit 76, on the inner end
portion of the tie element.
It will be a~ ' that the rate of a~ . of tne individual
tie elements formed from the leftwardly advancing web 68, 68' in the tie element
attachment portion 60b of the machine 60 is a~lul '~, and ~
sequenced relative to the sequence and speed of folded web ~lv at the
central drive roUer 92. This sequencing is w..v. ~, achieved using the
~ IU~IU~DDU~ portion 198 of the wntrol system 192 lly depicted in
Fig. 12. The U~JIU~__~I, in response to the tie element attachment output
signal 226, transmits output signals 322, 324, 326, 328 and 330. Output signal
3æ is imdicative of the stoppage of the stepper motor 102, output signal 324 is
indicative of the .~ u ~ c, dies 318, 320 being in their downward position,
20 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, 681 through its next increment. These signals, of course, are
' to position signals associated with the web handling
portion of the tie element attachment machine.
WO gS/19259 2 1 8 ~ 9 ` P~ 79
38
As previously mentione~, and as crh~ ir~lly illustrated in Fig.
1, the tie element attachment portion 60b of the machine 60 is pivotable between -
a lowered, solid line op~rating position and a raised, dotted line access position.
According to a feature of the present invéntion, ~ ' control means 331
5 (Fig. 1) are provided to monitor the cu~,~...liv~ operation of the machine
portions 60a and 60b when the tie element attachment portion 60b is in its
lowered position and the bag web 22 is being leftwardly conveyed a previously
described. In the event of a machine '' such as a jalnming of the
machine portion 60b, ~r a deviation in onc or both of the bag web loop lengths
10 from its maximum or minimum p. .. :~- .l length, the "y depicted
control means 331 are ~Dperative to upwardly pivot the machine portion 60b (by
operating suitable drive means not illustrated) to its access position while the bag
web æ continues to be produced and run through the machine 60.
To effect tbis automatic upward pivoting of the machine portion
60b, a~ condi~ion signals 331a, 331b are i ' to contrDI means
331 from the r 198, the signal 331a being indicative of sensed
operating condition of the machine portion 60a, and the signal 331b being
indicative of a sensed operating condition of the machine portion oOb. If either
signal 331a or 331b is indicative of a r '- of its associated machine
portion the control means 331 output a signal 331c tD energize the
'' ~ drive means which, in tum, upwardly pivot the machine portion
60b. The control means 331 may, at this time, also transmit an output signal
331d used to energize an audible alarm (not illustrated).
The overall operation of the machine 60 is adjusted and controlled
wo 95119259 2 1 8 1 1 4 9 . ~ J. C- 179
39
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 i ~, t; 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
5 adjustment dial structure 340 is provided for inputting to the machine the length
of the individual bags being driven ~ ;Lu..~. To monitor the number of bags
which have passed through the machine 60, ~ ul cumulative counters 342,
344 are also provided. Finally, ~lul on-off switch controls 346, 348, 350
are ~ y provided to control the power, tie element 2tt~rhmPnt and
10 transport functions of the tie element attachment machine.
It has been found that an improved tie strap utilizing an adhesive
coated elongated tie element with a removable cover strip or a rPr~itinn~l
adhesive coated tie element strip without a removable cover strip may be applied
to the bags of the continuous process disclosed herein with only minor
. ~ of the process. Several variations of tbese adhesive-coated tie
straps disclosed im Figures 16, 17, 18, 22 and 23. Insofar as possible, like
parts will be referred to with the same numbers having a prime mark.
In Figure 16, an improved elongated tie element strip 62' is shown
attached near the open upper end at the side edge portion 42b of a bag B. Bag
20 B is shown as being separated at the 1 ~ cut ]ine Sû from the flattened
dual layered web of bags B from the process of Figure 1 as ~ ,' ' by
Figures 2 and 3 with the improved tie element strip 62' instead of tie element
strip 62. It is I ' ; ~ that the orientation of the folded bag web with or
without a gusseted side edge as in Figure 4 is usefully equipped with tie element
2181149
WO 95/19259 PCI/US9r,100~79
62!. Tie element 621 has an inner end portion 62al, an outer end portion 62b'
and an ' portion 352 extending be~ween the inner and outer end
.
portions. Elongated st~ap 621 termina~s at a free outer end 354. Tie element
621 has an outer surface and an inner surface. The inner surface facing bag B
is coated with an adher,ive 358 extending from dotted line 356 to outer end 354.
The adhesive 358 is covered with a removable relear,e coated cover strip 360
which covers the entire surface of adhesiw 358. There is no adhesive on inner
end portion 62al beyond line 356 which definer, the beginning of inner end
portion 62al. The inner end portion is ~ 'y attached to the side portion
of the flattened bag body by a means for attaching . , ~ a heat seal or a
permanent adhesive. An oval shaped heat seal 362 preferably I ly seals
inner end por~,n 62al to both layers of bag edge portion 42b. If the bag edge
portion is gusseted as in Figure 4, the inner end of the strap is preferably heat
sea'led to all four layers.
lS Flgure 17 shows how the open upper end of bag B is gathered into
a circu'lar closed ~ and closed with elongated ~ie element 62' or the
thereof. The circular closed . ~ is formed by the user's
hand and creates a narrow closed neck where the sides of the bag are brought
;together. Cover strip 360 is easily separated away from adhesive 358 and
20 iremoved. The tacky pressure sensitive adhesive 358 is wrapped around the
gathered top of the bag in contact with the outer side surface of the bag in partial
u._.L~ lg orientation with itself. rle element strap 621 is long enough to
tightly close the top of the bag as shown in Figure 17 with the outer end portion
62b~ u.~ the inner end portion 62a~. The outer surface of the tie element
WO 9~/19259 21~ PCT/US95/0/i479
41
strip is not release coated, and thus adhesive 358 on the inner surface of outer
end 62bl sticks well to the outer surface of inner end 62al. The adhesive 358 on
the inner surface of the --- " portion sticks to the outer surface of the
gathered bag top. Yet it is possible to undo the strap by peeling the outer edge
5 354 in case the bag needs to be reopened by stripping outer end 62b' away from
inner end 62al and pulling the tie element away from at least a portion of the
outer sur~ace of the bag. Bag B is reclosable by ~ the tie element
around the gathered top of the bag to the c~ of Figure 17.
In order to facilitate ~ y of bag B, the last part of outer
end portion 62b', say a quarter inch, adjacent outer edge 354, may be bare of
adhesive 358 to provide an unsealed flap. The unsealed flap provides a place to
grip the outer end of the tie element in order to peel outer end portion 62b' away
from inner end portion 62a'. Similarly, an unsealed flap may be provided on the
",~1;1~. -1;....~ of Figures 18, æ and 23. The length of the tie element is selected
15 with respect to the bag so that when the top of the bag is tightly gathered
together with the fingers, the outer end portion of the tie element overlaps the
inner end portion. For a garbage bag B, this is normaUy a length in the range
of 4 to 8 inches.
A, .l;l; -~;.-.~ of the improved -" .~ elongated tie
element 62' is shown in Figures æ and 23. ~ Figure 22, a, .l;ri. -l;.. . of the
improved adhesive-holding strap is designated generaUy by the reference numeral
62'b. It is the same as tie element 62' e%cept that in this case, beginning at line
356, the inner surface of tie element 62~b is coated with a ~ adhesive
364 aU the way to outer end 354. The bare of adhesive inner end portion 62a'
. .
WO95/19259 2181149 r~ r~-,79
42
-is still fixed at tlhe edge portion 42b adjacent the top of bag B with heat seal 362.
However, the lC~.~;I.iu~ adhesive 364 is selected to only lightly tack (adhere)
to the outer surface of bag B. The IqJUi~i~LiU~ adhesive permits tie element 621b
to be relatively easily pulled away fr;om the surface of bag B when it is desired
5 to gather up the top and close the bag by wrapping the tie element around the
gathered bag. R~citin~l adhesive 364 has the property that when outer end
62bl is overlapped in contact with the outer surface of inne} end portion 62al, a
strong not so easily removed bond is created which holds the gathered top of the
bag in the enclosed ~ The inner and outer surfaces of the tie element
10 are altered by a treatment means to greatly enhance adherence of an adhesive.
Treatment means, suclh as by corona discharge, of the outer surface of the tie
element allows adhesive 364 to adhere much better to tlhe tie element than it does
to the bag surface~
Figure 23 shows another ....YI;I~ ;.,.. 621C of the improved
adhesively coated elongated tie element of Figure 16 in which adhesive 358 is
protected with removable cover $rip 360a from line 356 to its outer end 366
short of outer end 354 of the tie element strap. The only real difference between
elongated tie element 621C and tie element 621 is that a small portion of the outer
end of cover 360 has been removed. This permits adhesive 358 on tlhe inner
20 (under) surface of outer end portion 62bl to lie in contact with the outer surface
of bag B when the strap lays flat again$ the side of the flattened bag. A patch
of exposed adhesive extending from end 366 of the cover to end 354 of the tie
dement can be adjusted in the amount of exposed area or ~n the strength of the
adhesive to tack the ends of tie elements 62~c down, yet permit the tie elements
~ WO 95119259 2 1 ~ t 1 4 ~ -
43~
to be separated from the outer surface of the bag without tearing the bag. To
facilitate separation of the tie element for use, it can be noted that the porlion of
the adhesive covered by removable cover strip 360a, which may be at least
several inches long, provides a finger hold to insert fingers for quite easily
5 separating the tacked end portion 62bl from the bag surface.
Figure 18 is another ~ A of the improved adhesively held
strap in which the strap 621a is fixed at the side edge portion 42b of bag B by
he_t seal 362 at inner end portion 62al. The strap has an outer end portion 62bl
which terminates in the free outer edge 354. In the case of elongated tie element
621a, there are t~vo patches of adhesive 368, 372 separated l.~.~ci~ A;-~A11Y by a
portion of the tie element, which are designed to overlap and seal when the strap
is wrapped tightly around the gathered open top end of the bag. There is an
iAner patch 368 on the outer surface of the tie element. Patch 368 has an inner
edge 356 ccl~ r ' _ to the line 356 iUustrated in Figure 16 for tie element
621. IiAner patch 368 is covered by a removable cov patch 370 rnade of the
same material as cover strip 360. Similarly, the inner surface of outer end
portion 62bl is provided with adhesive patch 372 which e~tends to the outer edge
or nearly to outer edge 354. Patch 372 may be nearly square having an iiAner
edge 374 the same distance from the outer end of the strap as the width of the
20 tie element. Outer adhesive patch 372 may be covered with a removable cover
patch 374 which is shown in phantom. In use, both cover patches 370, 376 are
stripped off the tie element e~posing the adhesive patches 36~, 372 and the tie
element is wrapped around the gathered top of the bag as shown in Figure 17
whereby adhesive patch 372 is brought into ~ contact with patch 368
_ _
wo 95l19259 2 ~ 9 . I/~J ' t - 179
44
to bond together preventing the bag from coming open.
The polyolefin bags B are produccd b~y the process illustrated in
Pigure 1 preferably fro n blown pol~ yl~ .._ fil~. Although the individual bags
are shown to be formed with seals forming the tops and bonom placcd transverse
S to the 1~ direction in which the bag web is moving, it is to be
und~rstood that the individual flanened bags could be formed in an orientation
turned nincty degrees from that shown. In such a case, the top and bottom of theindividual successive bags formed on the moving web of bags would have tops
and bottoms parallel t~ the direction of movement and the sides of the bags
would be formed by seals transverse to the web direction. The tie element
anachment machine could then be tumed ninety degrees from the position shown
in Figures 1, 9, lO and 21 if it is desircd to attach individual tie elements
wherein the tie elements applied lie parallel to the tops of the individual bags to
which they are anached. The film, which comprises the flattened bag web, is
typically very thin. The strap material is preferably made from a web of
P~IJ.,II-YI~ _ material rather than a different material from the bag web to
facilitate Iri"u~ g scrap. The strap thickness may be in the range of .0005
to .005 inches, more preferably in the lower end of the range. The strap is
preferably made from a higher density higher melt inde~ pol~_ll"~l~ ..c film than
that of the bag web material. The tie element is preferably 1/4-2 inches wide
and attached between about 24 inches from the top of each bag. The tie element
material must have sufficient strength to permit it to be drawn tightly around the
gathercd top of the bag and held in place without tearing or breaking. It shouldhave enough strength ~o permit the adhesively coated tie element to be stripped
~WO95/19259 21 8~ p~ ""~ ~79
away from the bag web without tearing or brea~ing. The tie element web can
be made from a single or ble~d of resins ~cd or several resins the
same or different coextruded into two or more layers. The tie element web is
preferably treated on both sides by a treatment such as a corona treatment which
5 enhances adherence. The improved strap material is preferably printed on the
outer surface and adb~iYely coated on the inner surface, except for the patch in
the " ~ of Figure 18, where in both cases the corona treatment enhamces
the adhesion of the printing ink or adhesive, as the case may be.
The suitable adhesive is at least mildly adherent to pvl~
10 film and preferably as thin as possible for c It should not be thicker
than the material it is applied to, have high shear strength and not split or
separate when the tie element web and its adhesive is pulled away from the bag
material after having once been used to seal it.
The term "I~ with respect to adhesive is used in the
15 sense that the tie element with the l~ lA. ' ;- --- -~ adhesive c m be separated from
a bag substrate and .~ Yi adhesively a number of times. Another
of the l~ l adhesive is that it can be lightly adherent to the
bag but have strong adherence to the tie element or to itself. The term
l1 in term of art in the adhesive industry. Even though the tie
20 element web with ~ ;.- -l adhesive on one side is easily stripped away from
the bag surface, it strongly adheres to the surface of the strap which has been
corona-treated for ink adhesion. It also strongly adheres when it is in contact
with itself. The fact that the strap is made from a higher melt index polyolefin
also enhances adhesion 1.~ because the adhesive has greater adherence
wo 9SIl9~9 2 1 8 1 1 ~ ~3 i 1 ~11.)..~5~- 179
46
than to the lower density polyolefin normally used for thin bag rr~ *~m
The backing or cover ~,may be a ~ Liu..~lly release coated
paper or ~ul~. IL~I~ . . or any like n aterial.
The adhesive employed in the ' ~ ' of Figures 16, 18 and
S 23 can be a conventiollal pressure sensitive adhesive suitable for bonding with
polyolefin film. These adhesives are suitably protected with a removable release
coated cover strip until use. rv~ ul~Ltiull of such .,u..~...tiu..al a&esives should
produce a fairly strong bond with the bag material that can be separated with
difficulty in case a user needs to unwrap the adhesive coated tie element to
reopen the bag.
The lI,~i~;liU.Ial adhesive used on the modified tie element of
Figure 22 has no release coated cover strip. Therefore, it must be easily
strippable away from the surface of the bag. An example of a Ic~
adhesive that is believed to be suitable is available from Minnesota Mining and
r ~ r ' ' Company (3M), St. Paul, Minnesota, identified as product number
4268-NF industrial adhesive which may be applied by a variety of processes.
Other 3M r "' 1 adhesives can be formulated for the job.
Figures 19 and 20 are schematic j11,.~t~,1;"..~ showing how rolls
of tie element web material nnay be produced, although it is understood that other
20 method of applying adhesive, such as spraying may be employed. In Figure 19,
a polyolefin, preferably polyc~lyL..~. web 380 is passed over coating roller 382
after suitable ~ . t- " '' '~ for adhesion. The upper side passing over the coating
roller may have rrinting applied in line or in a previous operation. Coating
roller 382 may be a gravure roller operating in a cu..~,.-Liul-~l =er in pan 384
WO95/19259 21~ r_.,o.,,~o~l7
containing a desired adhesive in solution or dispersion. Distinct bands of
adhesive 386, 388 and 390 are applied to the underside of web 380. The web
is passed around several rollers and through a drying station 392. Station 392
may employ air or radiant heat to set the adhesive bands on the web.
S Rolls of release coated cover strip are applied over the adhesive
at a laminating station 394. Release coated cover strip rolls 396, 398, 400 are
applied ~ ly over adhesive bands 386, 388, 390 and pressed against the
adhesive bands by roller 402. The tie element web with adhesive bands and
release coated cover strips over the adhesive bands are wound as roll 404 on
arbor 406.
In Figure 20, semi-finished roll 404 is passed over slitter roll 408
and slitter knives 500 and divided into three separate rolls 641 wound on suitable
arbors. Each roll 641 has one of the bands 386, 388, 390 of adhesive, one of the
bands of cover strip 396, 398, 400 and an original bare edge portion 502 of web
15 380 without adhesive and without a cover strip. This bare edge portion is the
portion of the tie element web that ultimately comprises ilmer end portion 62a'
of the attached tie element.
It is evident that similar Wl... ' processes may be employed
to produce ~ ;r.~ ~;"--- shown in Figures 18, 22 and 23 of improved adhesive
tie strip 62~ of Figure 16. In the case of the ' ' of Figure 18, narrower
adhesive bands and narrower release coated cover strip will have to be employed
and the adhesive and cover strips are applied to opposite surfaces of bare (or
printed) tie element web similar to web 380. With the "~ of Figure 23,
a release coated cover strip narrower than the adhesive band may be employed
~181~49
WO9~/19259 1~~ 79
48
to leave an uncovered end portion. Initially, the whole band may be covered
with cover strip which is slit as it is laid down over the adhesive in a process ]ike-
Figure 19 and then removed through a pneumatic suction tube when the
individual rolls are unwound as shown in~Figure 21. For the "..~T;I~ ,.. Of
S Figure 22, the rolls of tie element web may be produced as in Figures 19 and 20
and the release coated cover strip sep~rated away as at roll 2911 in Figures 21
and wound up on a separate arbor (not shown) as rolls 641 are unwound. Any
rollerS coming in contact with the adhesive coated side can be coated or wrappedwith a release agent to p~event sticking. It may be desirable to span an endlessTeflon0 coated belt over and around rollers 3041 and 314' to fe~d individual
L~ y severed tie element strips to the vacuum belt 316'.
Although the inner end of the tie element shown in Figs. 16-23 is
shown to be attached to the side edge of the bag by heat sealing the inner end
porlion of the tie elements to the side edge of the bag in its flattened r~ri~tqti~m~
it is within the spirit ~f the mvention to 1 'y affLl~ the inner end portion
of the tie element to the side edge of the bags by other me~ms. One of such
means is to apply an adhesive layer, especially a heat setting adhesive layer tothe irmer surface of the ilmer end portion of each tie element. This inner end
, portion cOn then be ~r~qnq~rted as a tie element web 1~ ly in the bag
web direction in the ma~mer of Figs. 10 and 21 to a position wherein the inner
end portion of i .~ severed tie element strips c n be pressed and/or
heated in contact with the 'y stopped bag web at side edge portions
thereof to ~~ affL~ the inner end portion of a separated elongated tie
element to each of successive bags. Such tie elements employ a non-heat setting
;
~ wo 95/19259 21 8 114 9 r~l~c ~ ~ ~ 179
49
adhesive to wrap and seal the gathered top of bags as disclosed in Figures 16, 17
18, 22 and 23, the only difference being the use of adhesive to I 'y
attach the inner end of tie elements to individual bags instead of a heat seal.
Il~e foregoing detailed description is to be clearly I ' ~ as
5 being given by way of illustration and example only, the spirit and scope of the
present invention being limited solely by the appended claims.
