CA2022703A1 - Plastic film bag manufacturing and methods, and plastic film bags produced thereby - Google Patents

Abstract

ABSTRACT
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 por-tion. 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 longitu-dinal tension force on the plastic film web.

Description

r ~2~3 ~

IRON

PLASTIC FILM BAG MAN~FACTURING
~PPARATUS AND ASSOCIATED METHODS, AND PLASTIC FILM BAGS PRODUCED THEREBY
CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation~in-part of U.S.
application Serial No. 117,209, filed on November 4, 1987 and entitled "PLASTIC ~ILM BAG WITH INTEGRAL PLASTIC FILM TIE~
ELEMENT, AND ASSOCIATED FABRICATION METHODS", which is hereby \
incorporated by reference herein. ,~

BACKGROUND OF THE INVENTION
The present invention relates generally to the manufac ture 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 ~.S. application serial 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 plas-tic Eilm ~n tubular form, flattening the Eilm tube to Eorm a double layer "web", forming lateral weld lines and perforatlon lines across the web to defirle 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 bays. The laterally folded film web is then typically delivered to a packaging station spaced apart from the bag forming station, at a linear receivlng speed identical to the linear output speed of the bag forming station, where it i~ rolled or folded for packaging.
For the purpose of attaching accessories -to, forming IRON
~35531CT~

logos or heat seals on, or otherwisa modifying the individual bags prior to their receipt at the packaging stationt i~ is desirable to momentarily stop the web at each bag during the per--formance of a particular modification operation thereon - for example, the attachment of a plastic film tie element disclosed~
in U~S. application Serial 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 synchro-nously operated in a start-stop fashion to incrementally advance and then stop the entire folded film web section ex-tending bet-ween these two operating stations. While this is a quite logical approach, it signi-ficantly 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, shi-ftable multi--roller s-tructure may be utillzed -to engage and intermittently stop a por-tion of the Eolded plastic film web between the bag forming s-tation and the winder without slowing or interrupting the output and inpu-t web travel at these portlons of the overall bag forming apparatus. However, this high mass roller structure must be very rapidly shited back and forth -to stop each indivi-dual bag received thereby during the high speed bag forming pro-cess. Because of the rapidity with which the multi-roller structure must be in-termi-ttently shifted back and forth, very high shift forces result, requiring substantial power and preci-r ~ lf~ ~f ~

IRON

sion 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 clo-sure 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 veloci-ty of the bag forming station.
A web handling portion of the flexible tie element attachment machine grips the moving web, and advances i.t toward the winder, with driven roller rneans includlng an inlet drive roller, an outlet drive roller spaced apart from the lnlet 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 f:irst vacuum bin ~2~

IRON
s5531cIP

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 vacuums therein during machine operation.
As the folded web is drawn through the web handling por-tion 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 of the bag forming station and the winder mechanism. However, the control means intermittently operate the central drive roller, preferably via a s-tepper 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, deceleratecl, and then stopped again.
Each sequential stop-to-stop drive cycle of the stepper motor~driven cen-tral roller longitud.inally advances the portion ~o 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 suc-cessively 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 respec-tively positioned between the inlet and central drive rollers, and between the central and outlet driver rollers. The vacuums IRON

formed in the first and second vacuum bins exert yielding, down-wardly directed forces on the first and second slack web por-tions, created by air pressure differentials across the web portions, pulling web portions downwardly into the bins and posl-S tively, but rather gently, holding them in downwardly extending first 3nd 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 respec-tive vacuum bins as khe 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 pro-vided by the vacuum-supported second loop prevents the still-running outlet drive roller from imposlng tension force on the web sufficient to -tear it at one of its perforation lines posi-tioned 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 out-put and intake velocities a-t the bag forming s-tation and the packaginy 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 cons-tant elevated speed, decelerated, and then re-stopped, as previously described, to stop the next longitudinally successive 6~D

IRON

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 shor-tened second loop, to return the two web loops to their original length relatlonship at the time the cen-tral 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, down-wardly 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 ta~e-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 adjus-ted to compensate for dif-ferent bag lengths being run through the machine, and the vacuum bins are provided with movably ad~ustable front side walls to compensate for changes in the width of the particular folded plastic film web upon which the individual bays are formed.
The lengths of the vertically oscillatiny web loops within the first and second vacuum bins are continuously moni-tored by means oE vertically spaced series of photoelec-tric beam transmitters and associated receivers which :Lnput 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 duriny machine operation.
Additionally, the longitudinal position of each suc--cessive bag stopped on the central drive roller is con-tlnuously monitored by a unique perforation detection system which senses the position of the openable end perforation line of each bag ~ust before the bay is stopped on the cen-tral drive roller. The ~7 IRON
ss531CIP

perforation detection system, in a preferred embodiment thereof, includes a high voltaye electrode member spaced horizontally apart from an insulation~housed conductor supported on a central comrnon wall structure separating -the first and second vacuum bins. The electrode is pivotably supported withi.n the first vacuum bin and, in -the event that the -Eirst 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 elec-trode 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 i-t to transmit an OtltpUt signal to a microprocessor por-tion of -the con-trol means indicating the passage of another perforation line past -the elec-trode. This information is appropria-tely corre:La-ted to the rotational drive characteristics oE -the central drive roller -to continuously moni-tor the longitudinal orienta-tion of each individual bag stopped thereon.
In the even-t that the individual bags begin to be longi-tudinally mispositioned relative to the central drive roller at which they rnomentarily stopped ~due, for example, -to minor drive roller slippage)~ the microprocessor automa-tically adjusts the rotation of the central drive roller to correct -the misposi-tioning.

c~

IRON

The tie element attachment portion of the machine is pivotally mounted on the web handling portion thereof, above the inlet and central driva rollers, and rotationally supports a supply roll of an elongated plastic film web used to form the individual tie elements. During operation of the rnachine the plastic ~ilm 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 indi-vidual 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 o a ~usseted side edge portion of its associated bag, adjacent the openable end thereoE, by means of a first reciprocating heating die which also forms a slit through -the inner tie elernent end portion and the underlying gusseted side edge portion of -the bag.
The heat weld on the inner end oE -the -tie el0ment extends through all four plas-tic film layers of the gusseted side edge portion o the associated bag. Accordingly, very high strength connection is achieved between -the flexible tie element and its associa-ted bag.
To maint:ain each tie element in an extended position across an outer side surface of its laterally folded bag, to facilitate packagin~ of the bags, the outer end of each tie ele-ment is releasably restrained against such outer side surface of its laterally folded bag. While this releasable r~straint can be ~RON
B553lCIP

accomplished in a variety of manners, it is accomplished in a preferred ernbodiment of the present inven-tion using a second reciprocating heating die which functions to form by both mecha-nical force and thermal de-forma-tion, 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 ~rom 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 ou-ter tie element end is passed through the sli-t in the inner -tie element end and pulled to tighten the tie elemen-t loop around the open bag end and tightly close it. The slit leng-th :is preEerabl.y somewha-t shor-ter than the -tie element wid-th so tha-t as the tie elemen-t is passed through the sli-t -the tie element is crumpled and gathered in a manner inhibitiny loosening of the tie elemen-t loop around -the bag.
The tie elemen-t attachment machine o:E the present inven-tion may b0 conveniently placed "in-l.ine" in an existing plas-tic film bag forming system, and -the web handling por-tion of the machine may be used to sequential.ly s-top spaced longitudinal sec-tions of the continuously moving bag web for purposes other than tie element attachmen-t.

r~J ~

IRON

BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a simplified schematic side elevational view of a conventional in-line plastic film bag manufacturing system in which a tie element attachment machine of the present inven-tion is operably in-terposed -to attach to each of the lndividual b~g portions o~ the moving plastic Eilm web a flexible plastic film tie element which may be wrapped and cinched around the open bag end to tightly close it;
Fig. lA is an enlarged scale, horizontally foreshortened 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 plan 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, exitiny the tle element attachment machine, taken along line 3-3 of Fig. l;
Flg. ~ is an enlarged scale, horizontally foreshortened cross-sect:Lonal view through the moviny plastic film web, taken along line ~-~ of F.Lg. 2, illustrating -the represen-tative manner in whi.ch it :Ls laterally folded;
Fig. ~A is a cross-sectional view of a non-gusseted alternate embodiment of the overhanging right side edge portion oE the plastic filrn web depi.cted in Fig. ~;
Fig. 5 is an enlargement of the circled area "5" in Fig.
3;
Fig. 6 is an enlargemen-t o-f -the circled area "6" in Fig.
5;

F~ ~ fS~

IRON

Fig. 6A is an enlarged scale parclal cross-sec~lonal view through the filrn web, and the inner end of a fle~ible tie element, taken along line 6A-6A of :Fig. 6;
Fig. 7 is an enlargement of the circled area ll7~l in Fig.
5;
Fig. 7A is an enlarged scale partial cross-sectional view through a~ outer tie element end, and an underlying bag web portion, taken along line 7A-7A of Fig. 7;
Fig. 8 is a perspective view of a portion of one of the plastic bags and illustrates the manner in which its associated tie element may be used to tightly close the bag;
Fig. 9 is an enlarged scale, somewhat simplified perspective view of the tie element attachment machine;
Fig. 10 is an enlarged scale partial cross-sectional view through the tie element a-ttachment machine taken along line 10-10 of Fig. 9;
Figs. 11 and ll~ are schematic cross-sectional views taken through the tie element attachmen-t machine along line 11-11 of Fig. 9, and sequentially illustrate the alterna-ting movement of two slack plastic film web portions d:lsposed within a vacuum bin section of -the machine;
Fig. 12 is a schema-tic control diagram illustrating the feedback microprocessor control of inlet, outlet and central film web drive roller por-tions of the tie element attachment machine;
Fig. 13 is an enlarged scale fragmen-tary perspective view of a bag perforation detection system portion of the tie element attachment rnachine;
Fig. l~ is a schematic cross-sectional view through the perforation detection system, taken generally along line l~ L of r~ ~ 3 IRON

Fig. 13, and additionally illustrates certain control circuitry associated therewith; and Fig. 15 is a front side elevational view of a main control panel por-tion of the tie element attachment machine.

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 Vl. The bag forming station 20 includes a plastic extrusion die 24 which continuously extru des, 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. 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 defined by four layers of plastic film. AEter its exit from the rollers 28 and 30, the web 32 iS sequentially passed over -the rollers 3~ and 36 and fed through a heat sealing, folding and perforation apparatus 38.
lrhe schematically depicted apparatus 38, as its name i~plies, sequentially performs -three operations on the web 32 traversing the apparatus. First, i-t forms on the web a longitu-dinally spaced series of laterally extending hea-t seal weld lines 40, each of which extends between -the side edge ~2 of the web 32 and its opposi-te side edge ~ (see Fig. ~).
Ne~t, as cross-sectionally illustrated in Fig. ~, the web 32 iS laterally folded along the longi-tudinally ex-tending fold lines ~6 and ~8, the fold line 46 being laterally aligned with the side edge 4~, and the fold line ~8 being laterally inset from the side edge ~2. As best seen in Fig. ~, the lateral inset s~

IRON

of the fold line 48 causes a side edge portion ~2a (containing the gusset 31) to extend laterally beyond the balance of the laterall.y ~olded, flattened film -tube which u].timately 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 per-foration lines 50 is positioned leftwardly adjacent one of the heat seal lines 40. Acco.rdingly, -the heat seal. lines 40 and the perforation lines 50 form on the laterally folded plastic film web 22 e~iting the apparatus 38 a long.ltudinal series of laterally folded individual plas-tic film bags B which may ul-tima-tely be separated from one another by tearing the Eilm web 22 along the perforation lines 50. When this is done, each individual bag, ln the usual manner, has an openable end extendlng along one of the perforation lines 50, and a closed, opposite end ex-tending along one of the hea-t seal lines ~o.
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 mecha-nism 52, spaced apart ln a leftward direction from the bag forming station apparatus 38, at a constant linear speed V2 equal to the linear output velocity vl of -the film web 22 from the bag forming station 20. To provide tension control therefor, the IRON
B553lCIP

folded web 22 is passed beneath a stationary roller 53, and OVeL' a pivotally mounted dancer roller 54 prior to being drawn into the winder mechanism 52 wherein i.t is wound upon a suitable storage roll (no-t illustrated).
Operably interposed between the bag forming station apparatus 38 and the winder mechanism 52 is a tie element attach-ment machine 60 which, as subsequently described, is utilized to secure to each of the individual bags B, ad~acent 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 50. Machine 60 basi-cally comprlses a web handling portion 60a~ and a closure tie element attachment portion 60b 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. l) and a raised access position (shown in phantom in Fig. l).
As will be seen, the web handli.ng portion 60a operates to engage and leftwardly drive a longitudinally central port.ion of the folded web 22, pos:ltioned betweerl the apparatus 38 and the winder mechanism 52, and to sequentially and momentarily s-top each of the individual bags B and sta-tionari.ly position a longi-tudinal section -thereof for attachmen-t -there-to oE -the bag's asso-ciated closure -tie element 62. Importantly, this intermitten-t stoppage of each of -the individual bags moving from the apparatus 38 to the winder mechanism 52 is effected without appreciably al-tering the web output and intake linear velocities v1 and V2 and without impos:ing upon the longitudinally moving web 22 unde-sirably high longitudinal tension forces which migh-t otherwise tear the web at one of its perforation lines 50.

r

2 ~ 3 ~D

IP~ON

The tie element attachment por-tion 60b of the machine 60 is appropriately synchronized with -the web handlin~ portion 60a~
and is operative to form the individual tie elements 62, Erom a plastic film supply roll 64, and attach the formed tie elements to the sequentially stopped longitudinal sec-tions of the indivi-dual 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.
l and 5-8. The representatively illustrated tie element supply roll 64 is formed from a lateral half of an elongate~, flattened plastic film tube which has been cut along its central longitudi-nal axis with a heated slitting knife or wire. The lateral flat-tened 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 olded side edge 70 (Fig. 9)~ and an opposite, heat sealed edge 72 which was previously :Eormed by the heated slitting knife or wire. It will be apprecia-ted that, depending upon how the tie element web 68 was ini-tially 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 attachmen-t portion 60b 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 th0 tie elements 62 has an inner end porkion 62a which inc:Ludes a portion of the folded side edge 70 o the tie element web 68 and overlies the overhanging side edge portion 42a f the laterally folded plas-tic film web 22. The tie elemenk inner end portion 62a is firmly secured to the web side edge portion 42a by means of a circular r 2 ~ 3 ~

IRON
B55 3 lCIP

heat web 74. As best illustrated in Fig. 6A, the held weld 74 e~tends through all four plastic ~ilm layers of -the gusseted side edge portion ~2a f the folded web 22.
A longitudinal.ly extending slit 76 is formed through the tie element end portion 62a, and the underlying web side edge portion 42al and is positioned within the circular hea-t weld 74.
From its secured inner end portion 62a, 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 asso-ciated.
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 ~2a 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 E~ig. 1) so that the overhanging side eclge portion of the folded web 22 would have only -two plastic film layers (see the alternate side edge portion ~2b in Fig. ~A). The inner end of each tie element 62 would then be heat welded (along the circular weld line 7~) to the two film layers of the modified side edge portion ~2b.
Each of the tie elemen-ts 62 also has an outer end por-tion 62b, containing a portion of the heat sealed si.de eclge 72 of the tie element web 6~, which is posi-tioned laterally inwardly of the web fold ~6. The heat sealed ~oint at the outer end of the tie element 62 is not particularly strong due to the fact that it r ~

IRON

was formed by a heated slitting kni~e 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 elemen-t in that region.
To releasably restrain the tie element 62 in place across the top side of the laterally folded plastic film web 22, so that the web 22 and the a-ttached tie elements 62 may be smoothly drawn in~o the winder mechanism 52, five small dimples 80 (se~ 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 subsequen~ly 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 element end 62b can later be pulled apart frorn the bag without tearing the bag. To use a tie element 62 to tie off and close the open end of its associated bay B, the outer end oE the tie element 62 is slmply pulled apart from the bay film lay~r to which it is releasably restrained by the interlocking dimples 80 and depressions 80a. A-fter this is done, the tie element 62 remains very Eirmly anchored to its associated bag B by -the cir-cular heat weld 7~ at the inner tie~ element end.
As illustrated in Fig. 8, -the tie elemen-t 62 may then be used to tightly close and seal the open end 82 of i-ts associated bag B by simply wrappiny the tie elemen-t 62 around the open bag end, passing the outer tie element end portion 62b through the slit 76 to form a loop 8~ around the open bag end, and then ~c;A' ~ 7 ~ 3 IRON

firmly pul:Ling 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 ak 62C, 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 repre-sentative of a wide variety of tie element structures which could be attached to the individual bag portions of the laterally 10 folded plastic film web 22. A variety of alternate closure tie element configurations are illustrated and described in U.S.
application Serial No. 117,209 which has been incorporated herein by reference.
Referring now to Figs. 1 and 9, the tie element attach-15 ment machine 60 includes a generally rectangular support frame structure 86 which is floor supportable on four vertically ad~ustable support feet 88 positioned at the corners of the sup-port frame structure. The web handliny portion 60a of the machine 60 is carried by a front side por-tion of the frame struc-20 ture 86 and includes three drive roller members - an inle-t drive roller 90, a central drive roller 92, and an outle-t drive roller 94. As i:Llustrated, the rollers 90, 92 and 94 extend horlzon-tally, are laterally spaced apart, and are in essentially the same horizontal plane.
I'he three drive rollers longitudinal.ly extend in a front-to rear direction relative to the support frame structure 86, and are pivotally supported a-t their opposite ends on support frame portions 96 and 98. Roller 92 is spaced leftwardly from roller 90, and roller 94 is spaced leftwardly Erom roller 92. As 2 ~

IRON

schema-tically depicted in Fig. 12, the roller 90 is driven in a counterclockwise direc-tion by a motor 100, roller 92 is driven in a counterclockwise direction by a stepper motor 102, and roller 94 is drlven in a counterclockwise direction by a motor 10~.
Supported by a front side portion of the suppor-t 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 posi-tioned 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 i-ts opposite sides, and the roller 94 is positioned above and tangent to the bin wall 122.
For purposes la-ter described, a vacuum pump 132 (Fig. 9) is supported by the Erame structure 86 generally behind the left vacuurn bin 108 and has an inlet 13~. The inner ends of a pair of flexible vacuurn hoses 136 and 138 are connected to -the inlet 13~, and the outer ends of the hoses 136, 138 are respectively con-nected to the bottom vacuum bin walls 11~, 116 and comrmunicate with the interiors of the bins 106, 108. The interiors of the vacuum bins 106, 108 communicate with one another via a -transfer passage 1~0 formed through a lower end portion of the common central bin wal:L 118 and functioning to generally e~ualize the vacuums drawn in the two bins.

rf ~ ~ 3 ~

IRON

Also for purposes later described, a vertically spaced series of fi.ve photoe,lectric beam transmitting units 1~2, 1~4, 146, 1~8 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 receip-t by a vertically spaced series of beam receiving members 1~2a-150a mounted on the central bin wall 118. In a sirnilar fashion, a vertically spaced series of photoelectric beam transmitters 154, 156, 1~8, 160 and 162 are mounted on the left bin side wall 122 and are operative to right-wardly transmit photoelectric beams 164 across the interior o~
the left vacuum bin 108 for receipt by a vertically spaced series of corresponding beam receiving units 15~a-162a.
Referring now to Figs. 9 and 11, the web handling por-tion 60a of the tie element attachrnent machine 60 also includes a pair of pinch rollers 166 and 168 which are rotationally carried at theix outer ends by arm members 170, 172. The inner ends o~
the arm members 170, 172 are pivotally carried by a pair of upright support plate structures 17~ and 176 which project upwardly frorn 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 agalnst upper portions of the outle-t drive roller 9~ and the central drive roller 92. ~ 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, 18~
positioned along :right end sections of -the support frame portions 96, 98. The arms 180 are downwardly pivo-table to position -the pinch roller 180 against an upper portion of the inlet drive roller go.

2 ~

IRO~

Referring now to Figs. 1 and 11, the laterally folded plastic film web 22 exiting the bay 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 1a6, 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 5~ and upwardly into ~he winder mechanism 52. Utilizing the subsequently described control system 192 (Fig. 12), start-up of the web handling por-ti.on 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 1a8, restiny the web atop the three drive rollers so, 92 and 9~, and passing the web beneath roller 190 and operatively connecting it to the winder 52. A swl-tch 331 on a rnaln control panel 332 (Fig. 15) is then moved to :its "LINE" positi.on which, via a microprocessor l9a (Fig. 12), initiates the operation of rollers 90 and 9~ at rota-tional speeds corresponding to the linear web veloclty Vl.
~hen it is deslred to attach -tie elernents to the web 22, an operator moves the switch 331 from lts "LINE" positlon -to its "RUN" positlon. This signals the microprocessor 198 to energize the vacuum pump 132 (Fig. 9) and slow the rotation of roller 94 via an output signal 208 transmitted to its speed controller 210.
The slowing of roller 9~ causes the web 22 to be pulled down-wardly into the vacuum bin 106. In a manner subsequently IRON
35~31CIP

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 velo-city Vl, permitting the web 22 to be vacuum-drawn downwardly into bin 108 into a looped configuration 20~ until, in a manner sub-sequently described, the corresponding web loop 19~ 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 ini-tial length relationship between the web loops 194, 20~ 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" posi.tion which, via the microprocessor 198, lowers the tie element portion 60b of machine 60 to be lowered into its operative positi.on.
During the start-up, with the folded plastic film web 22 being outputted from the sealing, folding and perforating appara-tus 38, the motor 100 rotationally drives the :Lnlet roller 90 at a constant torque and at a counterclockwi~e, variable rota-tional speed corresponding to the linear web output speed V1 so that the web takeup speed of the roller 90 is equal to the linear web output speed from the apparatus 3~3. The above-described slowing of roller 9~ forms a slack portion of the web 22 between the rotati.ng drive roller 90 and the stationary central drive roller 92. rrhe operation of the vacuum pump 132 (Fig. 9) creates a yielding vacuum force within the vacuum bin 106 which draws I RON

this slack web portion downwardly into bin 106 and gently holds it in the illustrated, downwardly looped configuration 19~ (Fig.
ll). As the roller 90 continues -to rotate, the vertical length of the web loop l9~ downwardly increases.
The increasiny length of the web loop 19~ is con--tinuously monitored by the photoelectric beam receivers l~2a-150a supported on the central bin wall 118. It can be seen in Fig. ll 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 lg4 downwardly reaches a predetermined vertical level within the bin 106, a combinative signal 196 (Fig. 12) is transmitted from the receivers 142a-150a to a microprocessor 198, the signal 196 indicating that the vertical length of -the web loop 194 has reached its desired magnitude.
Upon receiviny the signal 196, indicating that the web loop 19~ has reached its desired initial length within the bin 106, the rnicroprocessor 198 responsively -transmits an output signal 200 to -the speed controller 202 which in turn, operates the motor 102 to step the cen-tral drive roller 92 at a faster speed than the inlet roller 90, thereby initiatiny the formation of web loop 20~. 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 bot-tom end of the web loop 204 is properly posi-tioned wi-thin bin 108 (see Fig. ll), the photoelectric receivers transmit through the microprocessor 198 a combinative signal 206 rf ~

IRON

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 10~
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 ~-08 to the speed controller 210, to thereby equalize the ro-tational speeds of the inlet and outlet drive rollers 90, 9~. With the three drive rollers 90, 92 and 9~
being operated at essentially constant speeds, the heights oE the web loops 194 and 204 are rnain-tained in their length relationship illustrated in Fig. ll during -the start-up phase of machine operation.
The microprocessor 198, and the speed controllers 202 and 210, are conveniently positioned wi-thin a rear side portion of the support frame struc-ture ~36 (Fig. 9) along with various other control components generally indicated by the reference numeral 21~. After the previously described start-up procedure has been accomplished, -the web handling positlon 60a of the machine 60 is converted -to its normal operating mode by moving switch 331 to its "R~N" position. In this operating mode, the inlet and ou-tlet drive rollers 90, 9~ are still rotated a~
constant and essentially iden-tical speeds, but the central drive - 2~ -r~ ~ 3 G.

IRON

roller is sequentially started and s-topped to sequentially and stationari.ly position longitudinal sections of each indi~idual bag B, ad;acent its perforation line 50 that defines i-ts openable end, to ready such longitudinal bag sec-tions for the attachment thereto o-E the tie elements 62 in a manner subsequently described.
Quite importantly, this sequential stoppage of each individual bag B at the central drive roller 9~ is accomplished without appreciably altering the constant output and intake velo-cities v1 and v2 of the longitudinally moving Eolded 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 stop-page is effected without imposing upon the web 22 undesir~ble 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. ll and llA.
In Fig. llA, the central drive roller 92 has been stopped, during -the continuing ro-tation of the inlet and outlet drive rollers 90 and 94, to -thereby momentarily hold the bag por-tion Bl thereon w:lth -the openable end perforation line 50b f the bag B1 being righ-twardly adjacent the central drive roller 92, and the opposite end perforation line 50a o:E the bag Bl being positioned upon -the web l.oop 204 being vacuum-drawn downwardly into the bin 108 through its open ~Ipper end 112. The longitudi-nal section of -the stopped bag B1 positioned atop the now sta-tionary central clrive roller 92 corresponds to the longitudinal section of such bag to which its closure tie element 62 will be } r~ ~ 3 IRON

affixed.
During its momentary stoppage, -the central drive roller 92 does not, of course, continue to drive a left side portion of the righ-t web loop 19~ into the left vacuum bin 108. However, the continued rotation o~ 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 func-tions to lengthen the web loop 194, while shortening the web loop 204, as respectively indicated by the arrows 220 and 222 in Fig.
llA. 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 9~ does during this period in which the central drive roller 92 is momentarily stopped, is take up the slack i.n the left web loop 204.
A~ter its tie elemen-t 62 is secured to the momentarlly . stopped bag ~1~ as rnonitored by an appropriate sensor 22~ (F'ig.
12), the sensor 22~ transmits an output siynal 226 to the rnicroprocessor 198 indicating tha-t the tie element has been attached. The roller 92 iS not commanded to rotate until photo-cel.l 150 is covered by web loop 19~, at which time the output si~nal 196 is transmitted to microprocessor 198. When the si~nal 2s 196 is received by the mlcroprocessor, the microprocessor automa-tically adjusts it:s output signal 200 to the speed controller 202 to operate the stepper motor 102 in a manner such tha-t the central drive roller 92 is sequentially started and rotationally accelerated to a counterclockwise rotational speed higher than

3` ~ ~

IRON

the speeds of the inlet and ou-tlet drive rollers 9o and 94, main-tained at -this elevated speed for a predetermined time period, decelerated, and stopped.
The result of this speed control cycle of the cen-tral drive roller 92 is that at the moment of its stoppage subsequent to the attachment of the tie element to the bag B1, the righ-t web loop 194 has been re-lengthened, and the left web loop 20~ re-shortened, to their original lengths as depic-ted in Fig. 11.
Additionally, the next bag B2 has been stopped at the central drive roller 92, with the openable end perforation line 50C of bag B2 positioned rightwardly adjacent the roller 92, and the opposite perforation line 50b being now positioned within the left vacuum bin 108.
After this stoppage of the central drive roller 92, which readies the bag B2 for the a-t-tachment of its tie elemen-t thereto, t~e web loops 194, 20~ again begin to respec-tively lengthen and shorten as illus-tra-ted in Fig. llA. The elevated speed level of the central drive roller 92, which shortens the web loop 19~, does not impose undesirably high longi-tudinal -ten--sion Eorce on -the loop 19~, since the roller 92 merely -takes the slack out of -the previously lengthened loop 19~ agains-t -the yielding, downwardly direc-ted vacuum force on such loop within the right vacuum bin 106.
I-t 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 19~ and 20~, permits the sequential stoppage of each individual bag withou-t overstressing the web 22 or appreciably altering the llnear outpu-t and in-take speeds v and v2 of the web.

~ J3f~ 3 IRON

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 ~2 sequen-tially advances the web a distance equal to the length of the individual bags being produced, and that -the tirne period between stoppages of the roller 92 is coordinated to essentially equalize the lengths oE the web loops 194, 20~ each time the central drive roller is stopped.
In addition to precisely controlling each web advance-ment length of the roller 92, it is also important to insure that as each individual bag is stopped at the central drive roller, the openable end perforation line of such bag is properly positioned rela-tive to the stopped roller so that each attached tie element is properl.y positi.oned on its associa-ted bag. ~n the present invention, this is achieved by the use of a specially desiyned perforation detection sys-tem 230 which is illustrated in Flgs. 11, llA, 13 and 1~.
The perforation detec-tion sys-tem 230 includes a hi~h voltage electrode member encased in an insulation tube 232 which is mountecl on the outer end 23~ o:E an L-shaped support arm 236 which extends rearwardly through an opening 238 formed in the rear side wall 12~ of the right vacuum bin 106 adjacent its upper end and the upper end of the central bin wall 118. The inner end 2~0 oE the support arm 236 is positioned behind the bin wall 12~
and is secured to a pivot pin member 2~2 which permits the sup-port arm 236 -to pivot about a horizon-tal axis, as indicated by the double-ended arrow 2~ .tn Fig. 13, be-tween an operating posi-3 ~

I~ON
s5531CIP

tion shown in Fig. 13 and a stowage position in which the electrode 232 and the outer end 23~ of the support arm 236 are rearwardly pi.voted 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 for-wardly through the bin wall opening 238 rests upon and is sup-ported by a horizontally extending tab portion 246 of the rear side bin wall 124, and the le~t or discharge end 232a of the electrode 232 is positioned slightly rightwardly 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 illustrated in Fig. 14, a cylindrical insulator member 250 has a boss portion 252 positioned wi-thin the bin wall opening 2~8, and a grounded cylindrical meta:L conductor member 25~ extends coaxially through the insulator member 250, the exposed right end of the conduc-tor member 25~. :Eacing the inner end 232a of the electrode 232.
~s illustrated in ~igs. 11 and 1~, a left side portion o~ the righ-t web loop 19~ is routed upwardly between the electrode 232 and -the insula-tor 250 onto -the central drive roller 92. Accordingly, during operation of the tie element attachment machine 60 the web perforation lines 50 are sequen-tially passed between the elec-t:rode 232 and the conductor 25~. The electrode 232 is connected via a lead 256 to a high voltage power supply device 258 which functions to cr0ate a high vol-tage potential across the gap between the electrode 232 and the conductor 25~.
Electrical discharge be-tween the electrode 232 and the conductor ~9~3 ~

IRON

25~ is normally preven-ted by the high dielectric constant of the plastic film ma-terial 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 perfora-tion line, to the conductor 2s4, 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-indlcative 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 posi-tioned.
Should the control system 192 detect a deviation in the desired position of the openable end perforatlon 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 con-troller 202 to momentarily increas0 or decrease the counterclockwise rotational steps of the roller 92 to readjust the stopped bag posi-tlon on the central drive roller 92, and correspondlngly ad~ust the signal 200 to increase or decrease the total number of ro-tational "steps~
imparted to the central drive roller 92 during one start-stop rotational cycle thereo~, thereby properly readjusting the longi-tudinal orientation of each individual bag as it is stopped at the central drive roller 92.

r ~?J~

IRON
s5531CIP

Normally, the rotational speeds of the inlet and outlet drive rollers 90, 9~ are -the same. However, at certain web velo-cities and bag lengths, the web loop 204 in the vacuum bin 108 may become too long or too short during the tie element attach-S ment 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 even-t that this occurs, the web merely pivots the support arm 236 rear-wardly to its stowed position in which l-t is disposed ent:lrely behind the bin wall 12~ by movement -through the bin wall opening 238 as previously described.
The con-trol system 192 described in con~unction with Fig. 12 is, of course, adjustable to compensa-te for different bag lengths belng driven through the web handling portion 60a of -the tie element attac:hment machine 60, the bag leng-th being -the distance between sequentially adjacent pair of perforation lines 50. The web handling portion 60a may also be easily adjusted to compensate for folded webs of different widths. This wid-th IRON
s5531CIP

adjustment is achieved in the present invention by providing means for selectively varying the effective front-to-rear wldths of the vacuurn bins 106 and 108. Such bin width adjustment is obtained by mounting the front bin walls 128, 130 for selective front and rear movement rela-tive 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 rnembers 26~, 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 engaye the opposite left and right side walls of each bin.
Sprocket members 278, 280 are respec-tively secured to the upper and lower nut members 268 and 270, and are drivingly interconnected by suitable chains 282. The upper nu-t members 268 have secured there-to suitable adjustmen-t knobs 28g which may be rotated to effect forward or rearward movement of -their asso-ciated front bin walls. For example, as viewed in Fig. 9, clock-wise rotation of one of the adjus-tment knobs 28~ effects forward movement oE its associated front bin wall, while counterclockwise rotation o-f the ad~ustment knob causes rearward movement of the front bin wall. In this rnanner, front-to-rear width ad~us-tment of -the two vacuum bins may be obtained so that the front-to-rear width of the bins is ~ust slightly larger -than the width of the folded plastic film web being used in a particular bag run. This r~

IRON
~35 5 ~ lCIl~

width adjustment capability assures that the downward vacuum force applied ko the web loops in each of the bins is efficiently applied to such loops.
The web handling apparatus 60a jus-t described is par-ticularly well suited to its illustrated use in handling the folded plastic film web 22 used in the in-line produc-tion of plastic bags in which it is necessary to momentarily stop longi-tudinally spaced apart sections of the continuously moving web to secure flexible tie elements to the stopped web sections.
lo However, it will be readily ~ppreciated 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 attach-ment portion 60b of the machine 60 will be described in detail.
The support spindle 66 of the tie element supply roll 6~ is rota-tionally supported on the upper ends of a pair of upright support bars 286 extending upwardly from the support brackets 182, 18~
positioned at a right front corner portion of the support frame structure 86 as previously described. Extending lef-tward]y from the support brackets 182, 18~ are a spaced pair oE support arm structures 288. The support arm structures 288 are secured to the brackets 182, 18~ and are pivo-tally carried by a support rod structure 290 so that -the tie element roll 6~1, 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 60b and its dotted line raised access posi~ion schematically depicted in Fig. 1.
As bes-t seen in Fig. 10, the tie element web 68 e~tends downwardly from the supply roll 6~ and is passed under a dancer ~ f~ 3 ~
G~

IRON
B -,, 5 ? 7 ~~.1 T~

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, beneakh a lower guide roller 294, and across a support plate member 296 extending between and supported by the support arm structures 288. As i-t leftwardly exits the support plate member 296, the wek 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 recipro-cating heating die 306, carried by the left support arm structure 288 and positioned above the support plate member 296, forms the lS weld lines 78 (Fig. 7) on longitudinally spaced apart sections ofthe leftwardly moving tie element web. As the web, with the weld lines 78 thereon, leftwardly exits the guide roller 300, it passes be-tween the base and reciprocating knife portions 308 and 310 of a vertically reciprocating sli-ttin~ knife mechanism 31.2.
Operation of the vertically reciprocating knife 310 transversely separates the individual -tie elements 62 from the lef-twardly 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 31~
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 lef-twardly transports the individual tie elements 62, and posltions the leftmost tie element direc-tly above the central IRON

drive roller 92 and the longitudinal section of the folded plastic film web 22 momentarily stopped thereon. With the left--most tie element 62 stopped in this position, its inner end portion 62a extends forwardly beyond the font side edge of -the vacuum belt and is positioned over the overhanging side edge portion 42a of the folded web 22 (Fig. 4), and its outer end portion 62b (which extends outwardly beyond the rear side edge oE 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 posi-tioned 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 lef-tmost tie element 62, and -the hea-ting die 320 is used to form the circular weld line 7~, and the slit 76, on the inner end portion of the tie element.
It will be appreciated that the rate of advancernent of the individual -tie elements formed from the leftwardly advancing web 68 in the tie elemenk at-tachment portion 60b of -the machine 60 is appropriately and intermittently sequenced relative to -the sequence and speed oE folded web advancement at the central drive roller 92. This sequencing is conveniently achieved using the microprocessor portion 198 of the control system 192 schemati-cally depicted in Fig. 12. The microprocessor, in response -to the tie element attachment output signal 226, transmits ou-tput signals 322, 32~, 326, 328 and 330. output signal 322 is indica-r ~ ~ ~\

IRON
B5531C~P

tive of the stoppage OL- ~he stepper motor 102, output S1~
is indicative of the reciprocating dies 318, 320 being in -their downward position, output signal 326 is indicative of such dies beiny in their upward position, output signal 328 operates the slitter 31~, and output signal 330 advances -the tie element web 68 through its next incr0ment. 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 60b of the machine 60 is pivotable between a lowered, solid line operatins position and a raised, dotted line access position.
According to a feature of the present invention, appropriate control means 331 (Fig. l) are provided to monitor the coopera-tive operation of the machine portions 60a and 60b when the tie element attachment portion 60b is in its lowered posl-tion and the bag web 22 is being leftwardly conveyed as previously described.
In the event of a machine malfunction, such as a ~arnming of the machine portion 60b, or a deviation in one or both of the bag web loop lengths from its maximum or minimum permissible leng-th, -the schematica:Lly depicted control means 331 are operative to upwardly pivot the machine portion 60b (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 effecl this automatic upward pivoting oE the machine portion 60b, appropriate condition signals 331a~ 331b are transmitted to control means 331 from the microprocessor 198, the signal 331a beinq indica-tive of sensed operating condition of the machine por-tion 60a~ and the signal 331b being indica-tive of 2 ~ ~ ~ J ~ 3 ~
IJ ~

IRON

a sensed opera-ting condition of the machine portion 60b. If either signal 331a or 331b is indicative of a malfunction of its associated machine portion the control means 331 output a signal 331c to energize the aforementioned drive means which, in turn, 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 adjus-ted and controlled by the main control panel 332 (Fig. 15) which, as seen 10 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 15 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 cumula-tive counters 3~2, 34~
are also provided. Finally, appropriate on-o~f switch controls 3~6, 3~8, 350 are respec-tively provided to control the power, 20 tie element attachment, and transport functions of the -tie ele-tnent 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 25 solely by the appended claims.

What is claimed is:

Claims (66)

1. For use in conjunction with a flexible, strip-like material being continuously discharged from a first apparatus at an essentially constant longitudinal output velocity and forcibly captured at a longitudinal intake velocity essentially equal to said longitudinal output velocity by a second apparatus spaced apart in a first direction from said first apparatus, a method of sequentially and temporarily stopping longitudinally spaced sec-tions of the material, at a first location positioned between said first apparatus and said second apparatus, without appre-ciably altering said constant longitudinal output and intake velocities or imposing undesirably high longitudinal tension for-ces on the material, said method comprising the steps of:
engaging the material at a second location positioned between said first location and said second apparatus and driving the material engaged at said second location generally toward said second apparatus at an essentially constant linear speed substantially equal to said longitudinal intake velocity;
engaging the material at a third location positioned between said first location and said first apparatus and driving the material engaged at said third location generally toward said first location at an essentially constant linear speed substan-tially equal to said longitudinal output velocity;
forming and maintaining first and second slack portions in the material respectively positioned between said first and third locations, and between said first and second locations;
maintaining yielding forces on said first and second slack portions in a manner respectively forming therefrom first and second material loops each having a length and extending lengthwise in a second direction generally transverse to said first direction; and engaging the material at said first location and driving the material engaged at said first location generally toward said second location in a manner alternately stopping the material engaged in said first location, to thereby lengthen said first material loop and shorten said second material loop against the yielding force thereon, and then advance the material engaged at said first location at a linear speed greater than the linear material speeds at said second and third locations to thereby lengthen said second material loop essentially to the length thereof which existed prior to stopping the material at said first location, and shorten said first material loop, against the yielding force thereon, essentially to the length thereof which existed prior to stopping the material at said first location.

2. The method of Claim 1 wherein:
said step of maintaining yielding forces is performed by continuously exerting vacuum forces on said first and second slack portions of said material.

3. The method of Claim 1 wherein:
said steps of engaging and driving said material at said first, second and third locations are performed using first, second and third rotationally driven rollers which respectively and drivingly engage the material at said first, second and third locations.

4. For use in conjunction with high speed plastic film bag manufacturing apparatus including a bag forming station adapted to continuously output, at an essentially constant first linear travel speed, a plastic film web having formed thereon a longitudinally adjacent series of interconnected individual plastic film bags, and a web receiving mechanism spaced apart from the bag forming station and adapted to forcibly capture the outputted plastic film web at an essentially constant second linear travel speed substantially equal to said first linear tra-vel speed, web handling apparatus interposable between the bag forming station and the web receiving mechanism for engaging the moving plastic film web and momentarily stopping, in sequence, a predetermined longitudinal section of each individual bag portion thereon, so that a selected operation may be performed on each momentarily stopped longitudinal bag portion section, without appreciably altering the essentially constant first and second linear travel speeds or imposing undesirably high longitudinal tension forces on the plastic film web, said web handling appara-tus comprising:
a support structure;
roller means, carried by said support structure, for drivingly engaging the plastic film web outputted from the bag forming station and moving it generally toward the web receiving mechanism, said roller means including:
an inlet drive roller, an inlet drive roller spaced laterally apart from said inlet drive roller, toward the web receiving mechanism, in a generally parallel relationship with said inlet drive roller, and a central drive roller positioned between said inlet and outlet drive rollers in a laterally spaced, generally parallel relationship therewith;
drive means for rotationally driving said inlet, outlet and central drive rollers in a manner such that first and second slack portions of the plastic film web are respectively formed between said inlet drive roller and said central drive roller, and between said central drive roller and said outlet drive roller;
vacuum means for exerting a yielding vacuum force on said first and second slack portions to respectively form therefrom first and second plastic film web loops each having a length and extending generally transversely to said inlet, outlet and central drive rollers; and control means for regulating said drive means in a manner such that:
said inlet and outlet drive rollers are con-tinuously driven at rotational speeds corresponding to said first linear travel speed, and said central drive roller is alternately stopped, to engage and stationarily position a selected portion of one of the individual bags thereon, thereby causing the length of said first plastic film web loop to increase and the length of said second plastic film web loop to decrease, and then started and driven at a rotational speed higher than that of said inlet and outlet drive rollers until a corresponding selected portion of the next adjacent individual bag is engaged by said central drive roller and said first and second plastic film web loops are respectively shortened and lengthened essentially to the lengths thereof which existed prior to the stoppage of said central drive roller.

5. The web handling apparatus of Claim 4 wherein said vacuum means include:
first and second vacuum bins having open ends facing said inlet, outlet and central drive rollers, said first and second plastic film web loops extending through said open ends into the interiors of said first and second vacuum bins, respec-tively, and vacuum pump means, having an inlet portion communicating with the interiors of said vacuum bins, for exerting said yielding vacuum force on said first and second slack portions from which said first and second plastic film web loops are formed.

6. The web handling apparatus of Claim 5 further comprising:
means for continuously monitoring the lengths of said first and second plastic film web loops within said first and second vacuum bins.

7. The web handling apparatus of Claim 6 wherein said means for continuously monitoring include:
spaced series of photoelectric sensing means, extending along said first and second vacuum bins in directions generally parallel to the lengths of said first and second plastic film web loops within said first and second vacuum bins.

8. The web handling apparatus of Claim 7 wherein:
said first and second vacuum bins are positioned in a side-by-side relationship, are divided by a common central wall structure extending generally parallel to the lengths of said first and second plastic film web loops, and have outer side walls which face and are generally parallel to said common central wall structure, and said spaced series of photoelectric sensing means include spaced series of photoelectric beam transmitting units positioned on said outer side walls, and associated series of photoelectric beam receiving units positioned on said common central wall structure.

9. The web handling apparatus of Claim 6 wherein said control means further include:
means, responsive to a sensed excessive shortening or lengthening of one of said first and second plastic film web loops, for momentarily adjusting the rotational operation of at least one of said central and outlet drive rollers to compensate for said excessive shortening or lengthening.

10. The web handling apparatus of Claim 5 further comprising:
means for adjusting the widths of said first and second vacuum bins, in directions parallel to the edge-to-edge width of said plastic film web, to compensate for variations in the edge-to-edge width of the particular plastic film web being removed through said web handling apparatus.

11. The web handling apparatus of Claim 10 wherein:
each of said first and second vacuum bins has a side wall inwardly and outwardly movable relative to the balance of the vacuum bins, and said means for adjusting include means for inwardly and outwardly adjusting each of said movable side walls.

12. The web handling apparatus of Claim 4 further comprising:
means for sensing the stopped longitudinal orientation of each individual bag relative to said central drive roller.

13. The web handling apparatus of Claim 12 wherein:
each individual bag portion is joined to its longitudi-nally adjacent individual bag portions along a pair of longitudi-nally spaced perforation lines formed laterally across said folded plastic film web, and said means for sensing include perforation line sensing means for sensing the position of one of the perforation lines associated with each of said individual bag portions.

14. The web handling apparatus of Claim 13 wherein said perforation line sensing means include:
means for passing an electrical discharge through said one of the perforation lines of each of said individual bag por-tions as it approaches said central drive roller.

15. The web handling apparatus of Claim 14 wherein said means for passing an electrical discharge through said one of the perforation lines include:
an electrically charged electrode member positioned on one side of a portion of said first plastic film web loop, and an electrical conductor member positioned on the oppo-site side of said portion of said portion first plastic film web loop and facing said electrode member.

16. The web handling apparatus of Claim 12 wherein said control means further include:
means, responsive to a sensed longitudinal misalignment between the individual stopped bag portions and said central drive roller, for temporarily adjusting the rotational operation of at least one of said central and outlet drive rollers to effect a longitudinal realignment between the stopped individual bag portions and said central drive roller.

17. The web handling apparatus of Claim 15 further comprising:
current sensing means for sensing an electrical discharge from said electrode member through said one of said perforation lines to said conductor member and responsively transmitting a current-indicative output signal, and wherein said control means are operative, when the timing of said output signal relative to the rotational position of said central drive roller is indicative of a longitudinal misalignment between the individual stopped bag portions and said central drive roller, to temporarily adjust the rotational opera-tion of at least one of said central and outlet drive rollers to effect a longitudinal realignment between the stopped individual bag portions and said central drive roller.

18. The web handling apparatus of Claim 15 wherein:
said electrode member is pivotally mounted within said first vacuum bin and is engageable by said first plastic film loop, upon an excessive shortening thereof, to pivot said electrode member out of said first vacuum bin.

IRON
???????

19. A machine for attaching closure tie elements to the longitudinally successive, separable individual bag portions of a plastic film web being longitudinally delivered at an essentially constant linear speed from a bag forming station to a web receiving mechanism spaced apart from the bag forming station and adapted to forcibly capture the web being discharged from the bag forming station, each of the individual bag portions, when separated from the plastic film web, having an openable end, said machine comprising:
a web handling portion including:
a support structure, roller means, carried by said support structure, for drivingly engaging the plastic film web being discharged from the bag forming station and moving it generally toward the web receiving mechanism, said roller means including an inlet drive roller, an outlet drive roller spaced laterally apart from said inlet drive roller, toward the web receiving mechanism, in a generally parallel relationship with said inlet drive roller, and a central drive roller positioned between said inlet and outlet drive rollers in a laterally spaced, generally parallel rela-tionship therewith, drive means for rotationally driving said inlet, outlet and central drive rollers in a manner such that first and second slack portions of the plastic film web are respectively formed between said inlet drive roller and said central drive roller, and between said central drive roller and said outlet drive roller, vacuum means for exerting a yielding vacuum force on said first and second slack portions to respectively form therefrom first and second plastic film web loops each having a length and extending generally transversely to said inlet, outlet and central drive rollers, and control means for regulating said drive means in a manner such that said inlet and outlet drive rollers are con-tinuously driven at rotational speeds corresponding to said linear speed, and said central drive roller is alternately stopped, to engage and stationarily position a seleted portion of one of the individual bags thereon, thereby causing the length of said plastic film web loop to increase and the length of said plastic film web loop to decrease, and then started and driven at a rotational speed higher than that of said inlet and outlet drive rollers until a corresponding selected portion of the next adjacent individual bag is engaged by said central drive roller and said first and second plastic film web loops are respectively shortened and lengthened essentially to the lengths thereof which existed prior to the stoppage of said central drive roller; and a tie element attachment portion positioned adjacent said inlet, outlet and central drive rollers and including:
means for successively positioning a flexible tie element adjacent the openable end of each individual bag sequen-tially stopped at said central drive roller, and means for firmly securing an end portion of each tie element member to a side edge portion of its associated bag adjacent the openable end of the bag, the secured tie elements each being adapted to be wrapped around its associated bag in a manner tightly closing its openable end.

20. The machine of Claim 19 wherein:
said means for successively positioning include a roll of plastic film tie element web material, means for controllably pulling said tie element material from said roll, means for laterally cutting the tie element web material pulled from said roll to form therefrom a series of plastic film tie elements, and means for advancing the tie elements toward said central drive roller, and said means for firmly securing include a heating die member operative to heat weld said end portion of each tie ele-ment to said side edge portion of its associated bag.

21. The machine of Claim 20 wherein:
said heating die member is operative to form a circular heating weld area between said end portion of each tie element and said side edge portion of its associated bag.

22. The machine of Claim 20 wherein said tie element attachment portion further comprises:
means for forming an opening through each of said tie element end portions, and through its associated bag side edge portion, through which the opposite end of the tie element may be passed.

23. The machine of Claim 22 wherein:
said opening is an essentially straight slit having a length less than the width of its associated tie element.

24. The machine of Claim 20 wherein said tie element attachment portion further comprises:
means for releasably restraining the opposite end of each tie element to its associated bag so that the secured tie element longitudinally extends across an outer side surface of the plastic film web.

25. Apparatus for monitoring the positions, relative to a first location, of longitudinal segments of an elongated member being longitudinally moved past said first location, each longi-tudinal segment being positioned between a longitudinally spaced duality of perforated areas formed through said elongated member, said apparatus comprising:
an electrically charged electrode member positioned adjacent said first location on one side of the elongated member;
a conductor member positioned on the opposite side of the elongated member across from said electrode member and opera-tive to receive an electrical discharge therefrom through each of the perforation areas as they successively pass between said electrode member and said conductor member;
current sensor means for sensing each electrical discharge and responsively generating intermittent output signals each indicative of current flow between said electrode member and said conductor member; and means for utilizing the output signals from said current sensor means to successively monitor the position of each of the longitudinal segments of the elongated member relative to said first location.

IRON
?????

26. Bag making apparatus comprising:
means for continuously extruding a plastic film tube;
means for flattening the tube to a web configuration and forming along a side edge portion of the web a gusset, whereby said side edge portion is defined by four plastic film layers;
means for forming on the web a longitudinally spaced series of heat weld lines to define the closed ends of a series of bags;
means for laterally folding the web to a configuration in which said gusseted side edge portion projects laterally out-wardly from the balance of the laterally folded web;
means for forming a series of elongated flexible bag tie elements having inner ends;
means for anchoring the inner ends of said tie elements to said gusseted side edge portion of the laterally folded web at longitudinally spaced locations thereon each adjacent what will be an open end of one of the bags being formed; and means for converting the laterally folded web, with said tie elements anchored to said gusseted side edge portion thereof, to a packaging orientation.

27. A method of longitudinally conveying an elongated flexible material web comprising the steps of:
resting a generally straight length of the web on sta-tionary upper side surfaces of first, second and third rollers which are generally horizontally disposed and mutually spaced apart in a horizontal direction with said second roller being disposed intermediate said first and third rollers, each of said first, second and third rollers being independently drivable at a selectively variable rotational speed;
initiating rotation of said first, second and third rollers, and temporarily varying the rotational speed of at least one of said rollers, to longitudinally convey the web in a manner initially creating, and then maintaining, in the moving web, downwardly extending slack web portions positioned between said first and second rollers, and between said second and third rollers.

28. The method of Claim 27 further comprising the step of:
exerting downwardly directed yielding forces on the slack web portions.

29. The method of Claim 27 wherein:
said step of temporarily varying the rotational speed of at least one of said rollers is performed by temporarily varying the rotational speed of said second roller.

30. The method of Claim 27 wherein:
during movement of the web by said rollers the web is being delivered to said first roller from a web-forming station at a linear output velocity, and said method further includes the step of varying the rotational velocity of said first roller to compensate for variations in said linear output velocity.

31. The method of Claim 27 wherein:
the slack web portions, during movement of the web by said rollers, have an initial relative length relationship, and said method further comprises the steps of intermit-tently stopping said second roller, to stop a web portion thereon and lengthen one of the slack web portions while shortening the other one, and then rotationally accelerating said second roller to return the slack web portions to said initial relative length relationship thereof.

32. The method of Claim 27 further comprising -the steps of:
sensing a vertical length deviation of one of the slack web portions from a desired vertical length thereof, and temporarily altering the rotational velocity of one of said rollers to return said one of the slack web portions to said desired vertical length thereof.

33. A method of initiating longitudinal movement of an elongated flexible material web, and subsequently placing adja-cent longitudinal sections of the moving web in transversely looped operating configurations, said method comprising the steps of:
resting a length of the web on stationary side surfaces of first, second and third rollers mutually spaced apart from one another along an intial web drive path with said second roller being positioned intermediate said first and third rollers;
creating rotation of said first, second and third rollers to longitudinally drive the web along said initial drive path; and re-orienting adjacent longitudinal sections of the moving web to said looped operating configurations thereof by:
temporarily altering the rotational speed of at least one of said first, second and third rollers to create a first slack web portion between said first and second rollers, and a second slack web portion between said second and third rollers, exerting yielding forces on said first and second slack web portions to hold the same in looped configurations extending generally transversely to said initial web drive path.

34. The method of Claim 33 wherein:
said step of temporarily altering the rotational speed of at least one of said first, second and third rollers is per-formed by slowing the rotational speed of said third roller to initiate the formation of said first slack web portion, and then increasing the rotational speed of said second roller to shorten said first slack web portion and initiate the formation of said second slack web portion.

35. The method of Claim 34 wherein:
said step of increasing the rotational speed of said second roller is performed by rotationally stepping said second roller.

36. The method of Claim 33 wherein:
said step of exerting yielding forces on said first and second slack web portions is performed by creating differential pressure forces across said first and second slack web portions.

37. The method of Claim 36 wherein:
said step of creating differential pressure forces is performed by imposing a vacuum force on one side of each of said first and second slack web portions.

38. A method of manufacturing plastic film bags comprising the steps of:
continuously extruding a plastic film tube;
flattening the tube to a web configuration having a duality of opposite side edge portions;
forming a longitudinally spaced series of transversely extending heat weld lines on the web to define the closed ends of a series of bag portions on the web;
laterally folding the web to a configuration in which one of said side edge portions projects outwardly from the balance of the laterally folded web;
anchoring the one end of each of a series of enlongated flexible bag tie elements to said outwardly projecting side edge portion of the laterally folded web at longitudinally spaced locations thereon adjacent what will be the open ends of the bags being formed, each tie element having a free end adapted to be looped around and tightly close the open end of its bag; and continuously conveying the laterally folded web, with said tie elements anchored thereto, to a receiving location.

39. A method of fabricating a bag from a thin ther-moplastic tube in which the bottom of the bag is formed by a transverse heat seal and the top of the bag is openable by separating the tube, the bag having one end of an elongated tie element attached to one edge of the bag with the other end of the tie element free, to be wrapped around the neck of the bag to close the open end, comprising the steps of:
continuously extruding a thin film bag tube of the ther-moplastic material and flattening the tube into a bag web having opposite side edges;
sequentially forming a series of transverse heat seals at spaced intervals along the tube to form the bottoms of the respective bags, while moving the bag web along a line;
simultaneously moving a thin film tie element web along a controlled path to a heat welding element positioned at one edge of the bag web, while cutting short lengths transversely from the end of the tie element web to form an elongated tie ele-ment, heat welding each tie element to the edge of each bag at a point spaced from the transverse heat seal, and at least partially separating the bag web between the tie element and the transverse heat seal to permit the individual bags to the separated and form the open top of the bags.

40. The method of Claim 39 wherein:
the tie element web is tubular and is flattened to form a double layered web; and both layers of the tie element are heat welded to both layers of the bag web.

41. The method of Claim 39 or 40 wherein:
a gusset is formed in one edge of the flattened tube to form a four layered section along one side of the bag web and the tie element is heat welded to all four layers.

42. A method of forming elongated flexible bag tie ele-ments and operatively securing them to individual bag portions defined on a longitudinally moving plastic film bag web having a side edge portion projecting outwardly from the balance of the moving bag web, said method comprising the steps of:
longitudinally moving a plastic film tie element web having two plastic film layers along a controlled path;
sequentially severing successive longitudinal segments from the moving tie element web to form a series of elongated flexible bag tie elements;
transversely conveying each of the tie elements to a position in which it longitudinally extends transversely across an exterior side surface portion of the bag web with an inner end portion of the tie element overlying said side edge portion of the bag web; and heat sealing the inner ends of the tie elements to said side edge portion of the bag web at longitudinally spaced loca-tions thereon.

43. The method of Claim 42 further comprising the step of:
releasably securing the outer ends of the tie elements to said exterior side surface portion of the bag web.

44. The method of Claim 42 wherein:
said step of transversely conveying is performed by transferring each tie element to a rotating vacuum belt, with the outer end portion of the tie element projecting laterally out-wardly of the vacuum belt, which is operative to move the tie element to said postion thereof.

45. The method of Claim 42 further comprising the step of:
temporarily stopping successive, longitudinally spaced sections of the bay web during the performance of said step of said heat sealing step.

46. The method of Claim 42 wherein:
said heat sealing step is performed by forming a heat seal line extending along at least a portion of a non-linear closed path.

47. The method of Claim 46 further comprising the step of:

forming a slit through each tie element inner end portion.

48. The method of Claim 47 wherein:
said heat sealing step is performed by forming a generally circular heat weld line, and said step of forming a slit is performed in a manner positioning the slit within said generally circular heat weld line.

49. The method of Claim 42 further comprising the step of:
heat sealing an edge portion of the tie element to weldingly reinforce what will be the outer ends of the tie elements.

50. Apparatus for forming elongated flexible bag tie elements and operatively attaching them to bag portions of a longitudinally moving plastic film bag web having a side edge portion projecting outwardly from the balance of the bag web, said apparatus comprising:
a supply roll of plastic film tie element web;
means for unrolling the tie element web from said supply roll thereof and longitudinally moving the unrolled tie element web along a controlled path;
means for transversely severing successive longitudinal segments from the unrolled tie element web to form the tie ele-ments; and means for securing first end portions of the tie ele-ments to said side edge portions of the bag web at longitudinally spaced locations thereon.

51. The apparatus of Claim 50 wherein:
said means for securing include means for heat welding said first end portions of the tie elements to said side edge portion of the bag web.

52. The apparatus of Claim 50 further comprising:
means for releasably securing second end portions of the tie elements to the bag web.

53. The apparatus of Claim 50 wherein:
said tie element web has two plastic film layers, and said apparatus further comprises means for heat sealing an edge portion of the unrolled tie element web to weldingly reinforce what later become second end portions of the tie ele-ments.

54. The apparatus of Claim 50 further comprising:
rotating vacuum belt means for receiving successive ones of the tie elements and transporting each of them to a position in which said first end portion thereof overlies said bag web side edge portion and is positioned to be operated on by said means for securing.

55. A bag comprising:
a tubular body having a closure across one end to form a closed bottom and an opposite open top, the tubular body, when laid flat, having opposite side edges;
a gusset extending along one of the side edges to form four layers; and an elongated tie element connected at one end to all four layers to the gusseted side edge and having an opposite free end to provide a tie element which can be looped around the open top of the bag to close the bag.

56. The bag of Claim 55 wherein the bag is formed of a thermoplastic material, the tie element is formed of a ther-moplastic material, and the tie element is connected to the four layers of the gusseted side edge by a heat weld.

57. The bag of Claim 56 wherein the heat weld includes an area having a length substantially greater than its width, the area including a generally U-shaped section with the bottom of the U-shape facing the free end of the tie element.

58. The bag of Claim 57 wherein the area of the heat weld forms a closed loop.

59. The bag of Claim 58 further characterized by a slit extending through the tie element and all the layers of the gusseted side edge within the closed weld area.

60. The bag of Claim 55 wherein the tie element is a closed loop and two thickness of the tie element are connected to the bag.

61. The bag of Claim 60 wherein the bag and tie element are thermoplastic material and the tie element is connected to the bag by a heat weld.

62. A bag comprising:
a tubular plastic film body having an open end, a closed end, and a sidewall portion extending lengthwise between said open end and said closed end; and an elongated flexible bag tie element adapted to be looped around and tightly close said open body end, said tie element having a first end anchored to said sidewall portion of the plastic film body, and a looped por-tion defined by two elongated plastic film strips extending out-wardly from the anchored first end of the tie element and having their outer ends heat welded together.

63. The bag of Claim 62 wherein:
said plastic film strips are heat welded together by at least one transverse heat weld line positioned longitudinally inwardly from their outer ends.

64. A plastic film bag comprising:
a flattened, laterally folded tubular plastic film body having a closed end, an openable end, a side edge portion extending between said closed end and said openable end, and an outer side surface partially bounded by said side edge portion;
an elongated flexible bag tie element extending across said outer side surface, generally transversely to said side edge portion, adjacent said openable end of the plastic film body, said tie element being adapted to be looped around and tightly close the opened bag end and having a first end overlying said side edge portion, and a second end spaced laterally inwardly from said first end along said outer side surface of the plastic film body;
means for firmly anchoring said first tie element end to said side edge portion of the plastic film body; and means for releasably retaining said second tie element end against said outer side surface of the plastic film body to facilitate handling yet in a manner permitting easy separation therefrom when it is desired to use said tie element to tightly close the opened bag end.

65. A plastic film bag comprising:
a tubular plastic film body having an open end, a closed end, and a sidewall portion extending lengthwise between said open and closed ends;
an elongated flexible bag tie element adapted to be looped around and tightly close the open end of the plastic film body, said tie element extending exteriorly along said sidewall portion generally transversely to the length of said plastic film body adjacent said open end thereof;
means for anchoring one end of said tie element to said sidewall portion of the plastic film body; and means for releasably retaining the opposite end of said tie element against said sidewall portion in a manner permitting such opposite tie element end to be easily separated from said sidewall portion when it is desired to use the tie element to tightly close said open end of the plastic film body.

66. Bag making apparatus comprising:
extruder means for continuously forming a plastic film tube;
means for converting the tube to a web configuration;
means for defining individual bag portions on the web;
web handling means, including means for moving the web therethrough, for positioning the bag portions of the web for attachment thereto of flexible bag tie elements;
tie element attachment means carried by said web handling means for movement relative thereto between an operative position in which said tie element attachment means are adjacent the web and an access position in which said tie element attach-ment means are moved away from the web, said tie element means in said operative position functioning to attach flexible tie ele-ments to the individual bag portions of the web; and control means for sensing a malfunction condition of either said web handling means or said tie element attachment means in their operative position and responsively moving said tie element attachment means from said operative position to said access position in a manner permitting continued movement of the web through said web handling means.