CA1122171A - Square bottom bag and method of making same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A method and apparatus for manufacturing a square bottom bag is disclosed herein. The method comprises the steps of driving a web in a first direction and bending the web upon itself across its width as it is driven in the first direction to assume a U-shaped configuration, supporting the main panels of the web in the open U-shaped configuration and folding the side clos-ure forming panels towards one another to an overlapping relation-ship and securing the side closure panels in the overlapping re-lationship to form side walls of a bag. The bag forming machine consists of a frame, a former mounted in the frame and a guide means for guiding an unwinding web around the former and drive means for driving the unwinding web around the former. Folding means is provided at opposite sides of the former for engaging the side wall forming portions of a web and folding them inwardly around the former to form closed side walls of a bag. Roll stock specifically designed for use in the method and apparatus is pro-vided wherein a first pair and a second pair of bands of adhesive material of a type which is inactive to form a bond until placed in contact with an adhesive of the same type are applied to the inner and outer faces of the web adjacent said edges thereof.
The bands of the first pair are laterally spaced with respect to the bands of the second pair so as to be out of alignment with one another in successive turns of the roll stock such that the successive turns are not adhesively secured to one another. An empty square bottom bag is provided which consists of a front wall, a back wall and a bottom wall formed from a unitary panel and in-cluding a band of adhesive on the outer face of said panel extend-ing along the marginal edge portion of each side panel, the panels being folded inwardly so that the band of adhesive on one side panel is disposed at an interface with another side panel and thereby secures the side wall panels with respect to one another in an overlapping relationship to close opposite sides of the bag and retain front, bottom and back walls in an open U-shaped configuration.

Description

FIELD OF INVENTION
This invention relates to the manufacture of square bottom bags.
Various aspects of this invention relate to improvements in roll stock for manufacturing ~he bag, improvements in a bas structure, improvements in a method of forming a bag and a new bag forming machine.
These various aspects of the present invention are ~articularly suitable for use in the manufacture of paper bags.
PRIOR ART
In the manufacture of bags such as paper bags, it is customary for the ba~ to be manufactured by a bag manufacturer and shipped to the user in a knocked down configuration. Despite the fact that the bags are shipped from the manufacturer in a knocked down configuration, the bulk of the bags after manuactur~
is generally substantially greater than ~he bulk o the original roll stock from which the bags are manufactured. This results in large part from the various multiple folds which are formed in the bag. Thus, the problems associ~tea with the shipping and storing of bags in the knocked ~own configuration is greater than that experienced with the shipping and storing of roll stock in the foxm of a coil.
During the manufactuxe of square b~ttom paper bags by the conventional bag forming apparatus, th2 roll stock is creased to ~orm a tubular member having inwardly directed side yusset panels. In the forming of the bottom of the bag, a complex series of creases are formea. Each crease is formed so that the paper stock will be permanently set at the crease line. To achieve thls permanent crease, it is necessary to damage some of the fibers at each crease lin~. This has the effect of weakening the bag along each crease ~ine~ Tn th~ conventional manufacture of bags~ it is n~cessary to form crease lines extending transvers~ly a~ross the bottom of the bags in order to locate th~ bags in ~he lay-flat configuration. Thus, in forming weakened rrease lines exten~ing across the bottoln of the bag, the bag is automatically weakened at the point where it is subjected to maximum load, namely the crease line between the bottom panels and side panels.
Panels are produced in the knocked down configuration so as to be compact for shipping and storage as described above and the various creases which are formed implant a memory on the structure which will tend to return the bag structllre to ~he lay-down configuration when the ~ag is unsupported. As a result, when a bag is spened it is necessary to provide a retaining means of some type for retaining the bag in the open configuration to ; pre~ent it from returning to its lay-flat confi~uration. Because the bag always tends to return to its lay-flat configuration, it is difficult for the users, sueh as packers in a grocery store, to handle the bags during the bag loading operation. For this reason several devices have been previously proposed for use in mechanic-ally opening knocked down bags and retaining them in the open 20 con*iguration. These mechanisms have not, however, enjoyed any degree of commercial success and the reason for this is believed to be the inherent difficulty in engaging the opposite walls of a bag and moving them to the open position and holding them in the open position.
The conventional square bottom bag is formed from a single web of paper or the like which i5 folded upon itself to a tubular sleeve ~onfiguration wi~h longitudinal side gussets~ The bottom of the bag is foxmed by a complex series of folding and gluing operations and, as previously indicated, the bottom of th~
bag is inherently weakened by the various folding and creasing operations to which it is subjected. Fur~hermore, the side gussets tend to draw the front and back walls of the bag ~waxds one another even when the ~quare bottom is fo,rmed, making it dif-ficult to obtain access to the bag without holding the free end in the open configuration.
While it is customary to mar.ufacture bags f~om roll stock, the adhesive which is applied in the manufacture of a bag is generally applied during the manufacture of the bag in the bag making machine. The forming of the bottom closure of a bag in the conventional hag making machine is so complex that the indi- ', vidual skilled in the art would not consider attempting to apply adhesive to the web in the roll stock because of difficulties in attempting to register the various areas to which adhesive is applied when constructing the bottom. Furthermore, one would not normally consider applying an adhesive to a web of roll stock because of the risk of bonding the adjacent turns of ~he roll to one another. ~, The existing bag forming machines are large and complex ~r.
and expensive. The machines are specifiically designed to convert rol 3tock to bags which are discharged in a lay-flat configuration.
20 The ma~hines have many moving parts and are designed to operate at high spe~. The machines of the prior art are specifically designed j to form ~he complex square bottom structure of a bag and to fold and crease the web so that the bag which is formed thereby will retain the lay~flat configuration in which it is discharged.
SUMMARY OF INVENTION
It is an object of the present in~ention to provide ~n improved method of forming a square bottom bag.
According to one aspect of the present inventionf a method of forming a bag from a bag formi~g section of a web of bag forming material which has a length ~n a first direction and a width in a second direction at right anqles to said first direc-tion znd which includ~s a mai~ panel extending in said first direc-tion and bounded on either side by a side closure forming panel comprising the steps of bending said web upon itself across its wid~h to an open U-sha~ed configuration in which said main panel forms unitary, seri~llv c~nnected, front bo~tom and back walls which are closea in the confi~uration which they wi~l assume when said bag is open, supporting said main panel in said open U-shaped configuration, folding said side clcsure forming panels toward one another to an overlapping relationship and securing said closure forming panels with respect to one ano~her in said over-lapping relationship to form side walls of a bag.
It is a further object of the invention disclosed herein to provide an improved square bottom bag.
According to a further aspect of the present invention, a square bottom bag comprises a front wall, bottom wall and back wall formed from a unitary panel and arranged in an open-U-shaped configuration, first, second and third side panels projecting from opposite sides of said front, bottom and back walls respecti~ely, said first, second and third side wall panels being folded inwardly and secured with respect tv one another in an overlapping relation-ship to close opposite sides of said bag and retain said front, bottom and back walls in sai~ open U-shaped configuration.
It is yet another object of the present inve~tion to provide an improved roll ~tock for use in the manufacture of square bottom bags.

PREFERRED EMBODIMENT
The inventio~ will be more clearly understood after reference to the following detailed specification read in conjunction with the drawings, wherein Figure 1 is a pictQrial view illustrating a ~irst step in the forming of a square bottom bag from roll stock;
Pigure 2 is an enlarged detail of the portion of web to Figure l;
Figure 3 is a pictorial view illustrating the folding of the sides of the bag inwardly upon one another;
Figure 4 is a pictbrial view similar to Figure 3 showing a bag in the form in which i~ is discharged from the bag forming machine i.n anerect configuration;
Figure 5 is a sectional view along the line 5-5 of Figure 4;
Figure 6 is a sectional view along the line 6-6 of Figure 4;
Figure 7 is a partially sectioned pictorial view of a bag forming machine constructed in accordance with an embodi-ment of the present invention: with certain elements removed for convenience of illustration of the for~er about which the weh is guided.
Figure 8 is a view similar to Figure 1 showing a web in position wound around the former with the associated guide rails in position;

~'~'t~

Figure 9 is a view similar to Figure 8 showing a :Eirst step in the closure of the sides of the bag around the former;
Figures 9a and 9b are partially sectioned views illustrating the mechanism for severing the web to form an ancnor tab on the side portions projecting from the bottom wall of the web;
Figure 9~ is a sectional view taken along the ~ine 9c of Figure 9b;
Figure 10 is a view similar to Figure 9 illustrating the apparatus moving to the pnsition to permit dis~harge of the bag ~lerefrom in the open configuration;
Figure 11 is a sectional view along the line 11-11 of Figure 10;
Figure 12 is a diagrammatic sectional side view ~f a bag form.ing machine of the present invention showing the two positions of the flexible guide belts and the mounting of two rolls of paper stock;
Figure 13 is a diagram illustrating the timing of the various functions of the apparatus;

~ 'igure 14 is ~ pictorial side view of a bag forming length of web similar to Figure 1 illustrating a modifica-tion in the form of an alternative type of sealing means;
~ igure 15 is a pictorial side view showing the manner in which the side wall forming portions of the member of Fiyure 14 ~re *olded inwardly to overlapping position; and Figure 16 is a view showing the fol~ing of the end flap ~f Figure 15 inwardly upon the side walls to the closed posi~ion.
Fig~res 1 to 6 of the drawings ser~e to illustrate a metho~ of making a bag, a bag structure znd a roll stock for use in making a bag in accordance with various aspects of the present inYention.
Roll Stock ; In Figure 1 of th~ drawings, the reference numeral 10 refers generally to a coil of a material such as paper suitable ~or use in the manufacture of a paper bag. The coil 10 consists o~ a continuous web 12 which is wound around a core 14. The web has an outer surface 16 and an inner surface 18. A continuous band of adhesive 20 is located on the upper surface 16 in a band which is spaced ].aterally inwaraly from each side edge of the web.
A band 22 of a similar adhesive is applîed to the inner face 18 .

in a continuous band which is located between each side edge of the web and i~s associated band of adhesive 20. The adhesive bands 20 ana 22 are laterally spaced from one another so that they do not come in contact with one ano~her when the web is wound upon itself in ~he coil form. The adhesive is of a type which will not bond to the material frQm which the web is manufactured but will bond to another layer of the same adhesive such that if the adhesive in the band 20 is placed in contact w~th adhesive in a band 22, a bond will be formed therebetweenn The use of roll stock of the type described above is important in ~he manufacture of bags according to the methoa of ~he present invention as it serves to eliminate the need to have the manufacturer of the bag apply any adhesive to the web during the manufacture of the bag.
By the simple expedient of laterally displacing contact adhesives applied to the inner and outer surfaces of a roll ~f bag forming stock, it is possible to eliminate adhesive applying mecha~isms from a bag making mach~ne and ~his has the advantage of simplifying the mechanism which is required and simplifying - 20 the method of operation of the bag forming machine. By r~son of the fact that ~he adhesive material is pre-applied to the web, it is not necessary to include a holding time in the cycle of operation sufficient to permit curing of the adhesive. The contact adhesive which is pre-applied to the web is such that a bond may be made between the bands of adhesiv~ which are placed in contac~ with one another merely by pressing the bands one against the other with no need to effect a curing of the bond before releasing the cornpressive forces applied thereto to effect the bond~
A Co-Adhesi~e suitable for use in accordance with the present invention is manufactured b~ FI~DLAY INC~
i ,.," ~

a~d sold under the trade mark NIPWELD 207-939. Other similar co-adhesives are available from Industrial Adhesives Limited and sold under ~he trade name L3108.
Method of Forming Ba~s As shown in Figure 1 of ~he drawings, the web 12 is unwound from the coil 10 and is driven in the direction of the arrow A. The unwinding end i5 driven along a ~-shaped guide path as will be described hereinaft~r in detail with reference to the apparatus. As the web is guided along the U-~haped guide pa~h, it is caused to bend upon itself around a first rounded corner in the area 23 and thereafter around a se~ond corner in the area 24. It is important to note ~hat, while the web is caused to bend, it is not creased so that no transverse crease lines are forMed which will serve to weaken the web as a result of the bending of the web to the U-.shaped configuration illustra-ted in Figure 1. The required len~th of web to form one bag is then severed from the roll along the line 26. The b~ken lines 28 appearing in Figure 1 of the drawings serve to separate the panel 32 which forms the main p~nel o the web from the side closure forming portions 34~ .
The main panel 32 consists of a bottom w~U panel 36 and oppositely disposed front and back wall panels 38. The side wall orming portions which project from the bottom wall panel 36 are cut along lines 40 to form tabs 42.
As shown in Figure 3 of the drawings, the side wall - forming pvrtions 34a which project from the panel 38 are folded inwardly and, as a result of inward folding, the portion 34b which projects from the bottom wall 36 folds along a fold line 44 which extends from the base of the tab 42 to an adjacent corner of the bottom wall panel 36. In the next step of forming the bag, the side wall forming portions 34c are folded inward~ ~ again the r- d '~

portion 34d folds along a fold line 44 extending from the base of the tab 42 to an adjacent cornex of the bot~om wall~ ~hen the side wall forming port ons 34c are folded inwardly, the adhesive bands 22 which are located on the inner face thereof are placed in face to face contact with the adhesive band 20 on the ex~erior surface of the side wall forming portions 34a and are pressed to-gether to form a permanent bond therebetween. Similarly the portions 34b and 34d and the tab 42 are folded into a face-to-face relationship with the remainder of the side walls as shown in Figure 4 and are secured in the folded po5ition by reason of the fact that the adhesive band 20 is folded upon itself and is thereby bonded to it5elf and the adhesive band 22 of the inner face of the tab 4~ is placed in contact with a portion of the underlying a & esive band 20.
In Figure 4 of the drawings, the reference numeral 50 refers generally to a paper bag constructed as described above.
It will be noted that the bottom wall 36 and front and back walls 3~ of ~he bag are formed from a conti;nuous web and, as shown in Figure 5, the corner 37 formed between panels 36 and 38 is rounded so that the bottom is not weakenea by the bending of the web in the forming of the web to the V-shaped configuration.
It will be noted that none ~f the steps described above in the formation of the bag are such that the bag is creased or folded in any way which would tend to encourage movement of the bag to a knock-down configuration. As will be described herein-after, a crease may be formed along the longitudinal side edges 39 which will serve to retain the bag in the open configuration when it is removed from the former on which it is formed. Thns, the bag constructed in the manner described above has no "memoryn of any knock-down configuration. This is important in the ultimate use of the bag in many applications as it causes the bag to assume --~L --~ f.ih ~
an open configuratic)~ which will facilitate loading of the bag.
With reference to Figure 1 o~ the drawings, it will be ~een that the first step in the method of forming ~he bag compriseS
driving the web longitudinally of itsel~ in a first direction and bending the web as it is driven longitudinally of itself to an open U-shaped configuration. Thereupon, as illustrated in Figure 3 Of the drawings, the main panels 32 are supported in ~he open U-shaped configuration and the side closure ~orming p~nels are folded toward one ano~her to locate the adhesive bands at the margin~l edge thereof in an o~erlapping relationship and thereby secure the side walls in the inwardly folded position. Thereafter the flaps which project from the bottom wall are folded inwardly into a face-to-face relationship wi~h respect to the side walls to be adhesively secured as shown in Figure 6~ The bag forming length, ha~ing previously been sevexed from the coil, is dis-- charged in the open configuration shown in Figure 4 without any folds or sreases which will encoura~e it to move to a knock-down or lay-flat configuration.
Several mo~ifications of the bag and its method of manufacture will be apparent to the individual skilled in the art.
For example, the side wall forming portions projecting from th~
bottom wall 36 may be folded inwardly before the side wall form-ing portions 34a and 34c are folded inwardly. In this m~difica-tion, the adhesive band ~0 extending across the outer surface of the tab 42 would engage the adhesive band 22 on the inner face of the side wall forming portions 34a to secure the tab 42 and its associated side wall closure members with respect to the side walls of the bag.
Apparatus A machine for forming a bag is illustrated in Figures 7 to 12 of the drawings.

Former and Web Feeding Belts With reference to Figure 7 of the drawings, it will be 11 .

seen that a mandrel of fo~me~ 52 is supported between plates 54 and 56 o~ a frame in a yenerally horizDntal plane. The former 52 consists Df former plates 58 and 60 which are suppDrted ori, arms 62 projecting from the plates 54 and 56 of th,e rame~ The for~,er plates 56 a~d 58 each have a bag forming portion at one end thereof which has a first folding edge 64, a second folding edge 66 ar,d a third folding edge 68. The former plates 58 and 6D
are spaced from one ~nother a dist~nce substantially equal to the width of the front, boittom and back panels of a bag to be form,ed thereon. The forn~r plates 5~ and 58 are spaced from one another by means of a plurality of spacer shafts on which guide rollers are mounted. A first guide roller 70 extends transversely between i $he plates '58 and 60 adjacent the input end of the gl~de path, the inner periphery of which is joined by the folding edges 64, 66 and 68. A 5econd guide roller 72 extends transversely between plates 58 and 60 at the corner formed between forming edges 64 and 66 and a third guide roller 74 extends between the plates 58 and 60 at the corn,er formed between forming edges 65 and 68 A
fourth guide roller 76, a fifth guide roller 78 and a sixth guide roller 80 are located forwardly from the bag forming portion of the former plates. A pair of endless conveyor belts 82 extend around the first, second, third, fourth, fifth and sixth guide rollers. The fifth guide roller 78 also acts as a drive pulley for driving the belts 82 aro~nd the former and is for~,ed with teeth in the pulley recess to drivingly engage the teeth of the belts 8~. In extending between the first and second guide rollers 70 and 72, the conveyor belt5 82 extend along the guide path in substantially the same plane as the first folding edges 6~,. Simi- , larly, in extending between the second and third guide rollers and in extending between the third arnd fourth guide rollers, the ,_onveyor belts 82 extend in the planes of the second folding 7~ ~
~.ges 66 and the third folding edges 68, respectiyely, so that as will be descri~ed hereLnafter the bel~ 82 may ~erve t~ ari~e ~n unwinding web aro~nd the fo~mer.

Web Cutting Mechanism _ In order to sever a bag forming length of web from the endless coil ~f web material~ a cutter assembly is provided be-tween the fifth and first guide rollers 78 and 70. The cutter as~embly consists of a cutter blade 84 mounted tv reciprocate vertically between a pair of guide plates 86 and complementary cutter elements 88 which are spaced above the guides 86 to limit upward mo~ement of the web to facilitate cutting of the web by the cutt~r blade 8~. The complementary support elements ~8 are carried by arms 90 which depend from a beam 92 which extends trans-versely between plates 54 and 56 of the frame. The cutter blade 84 has extension springs 94 at either end thereof secured to pins 96 carried by plates 54 and 56. The extension springs 94 act as return springs serving to retain the cutter blade 94 in the lowered position when inactive. The cutter blade 84 has teeth which are V-shaped so that they oan be driven directly through the web - without any la*eral movement being required. This is of consid-erable mportance as it enables the drive mechanism for the cut-; ter blade to be in the form of a simply vertically recipxocating lever.
The operation of the cutter blade mechanism is best il-lustrated in Figure 7 of the drawings wherein it will be seen that cutter blade 94 is supported on a cross bar 126 which is mounted on the end of a rocker arm 128 which is in turn mounted to rock on shaft 130 which extends between former plates 58 and 600 A cam follower 1~2 is located at the other end of the rocker arm 128 and is positioned to be engaged by a cam 134 mounted on shaft 136.
Rotation of shaft 136 which is effected, as will be described here-inafter causes the cam 34 to move the rocker arm 128 about the ,, , , ...,, ~ .

shaft 130 to raise ~nd lower the cuttç~r blade 84 as required.
Power to Feed Conveyors The conveyors 82 are driven during the portion ~f the bag manufacturing cycle that is employed tG feed a bag-forming length around the former 52 to the ~-shaped configuration. The conveyors 82 are stationary when the folding of the sides o the web take place and when the bag is being discharged from the former.
The power source for the bag-fonrLing machine is a motor 100 which drives a sprocket 102 throuyh a reduction gear unit 104. t The sprocket 102 driYes a chain 106 around sprockets 108 and 110.
The sprocket 108 is ke~ed to a shaft 112 which is connected through a clutch 124 to a shaft 113 on which a fifth guide roller 78 is mounted to be dri~en therebyO When the clutch 124 is released the shaft 113 is coupled to the shaft 112 and is driven thereby. When the clutch 124 is engaged the shaft 112 is rotata~ly driven while tXe shaft 113 remains stationary. The operation of the clutch is regulated by a solenoid valve 120 which has arm 122 projecting outwardly therefrom to engage a control flange extending from the clutch. W~len the arm 122 is in the extended position engaging the flange of the clutch, the shaft 112 is out of engagement with the shaft 113. When the arm 122 is withdrawn by the solenoid the shaft 112 is coupled in dri~ing engagement with the shaft 113 by means of the clutch 124.
The fifth guide roller 78 is also a pinch xoller which cooperates with the second pinch roller 79 mounted on shaft 114. ~, A gear 116 on shaft 113 is meshed with the ge~r llg on shaft 114 and serves to xotatably drive the shaft 114 which in turn rotatably drives the pinch roller 79. The pinch rollers 7g and 79 must be driven for a period of time sufficient to cause the unwinding web to be driven around the former to the U-shaped ~;_ , coniguration ~hown in Figure 8. The period of time during which the feed conYeyOr mechanism is operably driven is con~rolled by a cam 280 which is mounted on shaft 136 which engages a con~rol switch 284 (~igure 10). The control switch 284 controls the opexa-tion of the solenoid 120 so ~hat when the control switch 284 is engaged by ~le cam 280, the solenoid is activated to withdraw the arm 122 to permit the shaft 113 to be driven by the shaft 112.
When the cam 280 moves out of engagement with the control switch 284 the solenoid 120 releases the arm 122 which moves into engage-mellL with the clutch 124 and disconnects the driving engagement~etween the shafts 112 and 113 so that the conveyors come to rest.
Guide Around Former While the former 52 serves to provide an internal yuide and support for the web and the conveyor 82 serves to pro~ide a drive mechanism for driving the web around the former, it will be ; apparent ~hat the web will not follow the contour of the former unless a guide mechanism is provided for engaging the external ~' surf ce of the web and guiding it around the former.
With reference to Figures 8 ,and 12 of the drawings, it will be seen that the guide mechanism for guiding the unwinding web in a guide path extending along the first support face of the former~ around the bottom support face of the former, and along the second support face includes a first pair of flexible guide belt~ 140 and a second pair of flexible guide belts lg2. The belts 140 and 142 are located directly outwardly from the conveyor belts 82. The leading end of each belt 140 is secured to a bracket 144 which is mounted on the transversely extending member 92, ad-jus~ment being provided by a longitudinal slot 146 provided in i' the bracket 144. Similarly one end of each guide belt 142 is mounted on a bracket 144 which is secured to a transverse memberof the frame (not shown). Brackets 146 are mounted on transverse ,,, ', suppor~ member 148 and extend toward ~he belts 140 and 142 and are spaced from ~he brackets 144 and s2rv~ ~o main~ain a substan-tial length of each belt 140 and 14~ in ~he plane of it5 associated run of the conveyor 82. The other end of each belt 140 is mounted Gn a- bracket or gate 150 and the other end of each belt 142 is mounted on a bracket or gate 152 (Figure 12~. The gates 150 and 152 are pivotally mounted on shafts 154 ana 156, respectively, to pivot between the closed position shown in solid lines in Figure 12 and the open position shown in broken lines in Figure 12.
When the flexible belts 140 and 142 are in the closea position shown in solid lines in Fi~ure 12, each belt extends around a corner of the former to form a substantially continuous guide path around the former. When the guide belts are ln the open position, they are spaced outwardly from the former a distance sufficient to permit a bag to be discharged from the former in an open configuration.
The mechanism for moving the guide belts between the open position and the closed position is illustrated in Figure 10 of the drawings. To avoid over complication of the drawings, only one gate opening mechanism is illuskrated. However, it will be understood that the mechanism for moving the gates 150 and that used for moving the gates 152 is identical, one being located abo~e and the other being located below the former~ The mechanism which i5 illustrated in Figure 10 include~ a lever arm 158 which i5 secured to the shaft 154 on which brackets 150 are mounted.
The cther end of the lever arm 158 is pivotably connected to one end of a connecting rod 160. The other end of the connecting rod 160 i5 pivotably connected to one end of a rock~r arm 162. The rocker arm 162 is mounted to pivo~ on shaft 164 which ex~ends from frame plate ~4. A cam follower 166 is mounted at the other end of the rocker arm 162 and i5 positioned to engage a cam 168 which is mounted on shaft 136 The main lobe of the cam 168 serves to retain the rocker arm 162 in ~he pOSi~ion shown in Figure lD
which holds the gates 150 in the open pOSition shown in Figure lO o When the cam 166 is rotated, the rocker arm 162 will pivot about the shaft 164 to move the brackets 150 between the open position shown in Figure 10 and the closed pOSition shown in Figure 12.
Main Cam Shaft The shaft 136 is ~he main cam shaft from which the prin-cipal mechanical mechanisms of the machine are controlled. The drive mechanism which rotatably drives the cam shat 136 will now be described with reference to Figures 7 and 10. The power source is the motor 100 which, as previously described with reference to Figure 7, drives the sproc~et 110 by means~of a chain 106.
The sprocket 110 is mounted on a shaft 170 which extends bctween frame plate 54 and former plate 58. P. sprocket 172 is mounted on the other end of shaft 170 and is connected by means of a chain 174 to sprocket 176 on shaft 130. Turning now to Figure 10 of the drawings, it will be seen that the shaft 130 has geaxs 178 and 180 keyed thereto. A bracket 182/ which is supported by the framer has a shaft 184 mounted for rotation therein. A
gear 186 is mounted at one ena of the shat 184 and is meshed with the gear 180 and a worm 190 is located at the other end of the shaft 184 and is meshed with a worm gear 192 on cam shaft 136. Thus, the motor 100 serves to drive the main cam shaft 136.
Cutter Mechanisms Having fed a web of bag forming material around the ~ormer to the U-shaped configuration illustrated in Figure 8 of the drawings, the cutter ~lade mechanism is operated to sever the bag orming length from the continuous web and the sides of the bag are then closed. As previously indicated, a tab 42 ~igure 1) is ~ormed between a pair of slits 40. In order to cut Q j ~

~rJI ~.
the web to form ~he slits 40, a knife mechanism is provided at each side of ~he former. The knife mechanism will n~w be described with reference to FigureS 9, 9a, 9b a~d 9c. It will be understood that a knife mechanism is located at each side of the former, although or simplicity ~f illustration only one knife mechanism is shown in Figure 9. Each knife mechanism includes a support block 194 which, together with a further support block 196 which will be described hereinafter, is mounted on an end plate 198 carried by frame plate 56. A pair of knives 20D prGject outwardly from the support block 194 in a spaced parallel relationship.
The support block 194 is rele sably secured with respect to the face plate 198 by means of a pair of mounting screws 202. A
pair ~f support arms 204 are mounted on the support br~cket 196 ~nd project outwardly therefrom. As shown in Figures 9 and 10 of ;~:s drawings, a spacer shaft 206 extends between the arms 204 and a paix of link arms 208 are mounted at opposite ends of the shaft 206 to pivot about the axis of the shaft 206. A shaft 210 extends betwe~n the link arms 208 intermediate the ends thereof and a rollex 212 extends between the inner ends of the lin~ arms 208 and is rotatable about its longitudinal axis. Two pairs of shear guide plates 213 are mounted on each shaft 210 to be movable therewith toward and away from a knife 200 to move a portion of a web located therebetween into engagement with the knives 200 to cut the web to form the slits 40.
Folding Mechanism Having formed the tabs 42, it i5 necessary to fold the side panels inwardly about the former. The folding mechanism will now be described wi~h reference to Figures 8, 9 and 10 of the drawings.
As bes~ shown in ~i~ure 9 of the drawings, four shafts 154, 155, 156 and 157 extend transversely between frame plates 54 and 56. Lever arms 21~ are secured to sh~fts 155 and 157 for movement therewith ~nd lever arms 216 are pi~o~ably mounted on sh~fts 154 and 156. The lever arms 214 and 216 are pi~otably connected at ~heir inner ends by a folding arm 218. It will be noted that each folding arm 218 has an end portion 220 projecting from the arm 216 toward the bottom support ~ace of the former. f The outer extremity of the end portions220 are elongated vertical-ly so that as ~hey are driven toward the plane of the bottom panel they do not damage the we~. The lever arms 214 and 216 are re- f 10 tained by the folding arm 218 so as to extend parallel to one another so that by rocking the shafts 155 and 157, the olding a~ms 218 will remain parallel to one anothPr while being moved towards and away from one another in an action plane spaced out-wardly from and parallel to the former plates 58 and 60.
Spring finger plates 219 are mounted on each folding arm - 218 and project inwardly therefrom toward the f~rmer plates 58 and 60. In use the plates 219 apply a pressure to the side formingpanels of the web which helps to maintain these panels in the overlapping relationship when the discharge load is 20 applied to the bag to drive it ~rom the mandrel. The plates 219 retard the for~ard motion of the side panels in a plane spaced from the plane of engagement of the discharge rollers and this draws the side panels toward one another during discharge.
The folding arms 218 are movable between the innermost position shown in Figure 9 and the outermost position shown in Figure 8 by a drive mechanism shown in detail in Figure 8. The drive mechanism includes lever arms 222 and 22~ which are secured to shafts 155 and 157 respectively. A connecting rod 226 ~as one end secured to the outer end of the lever arm-222 and a connecting rod 228 has one end connected to the outer end of lever arm 224.
The other end of the connector rod 226 is connected to rocker arm i, 230 and ~he other end of connector rod 228 is connected to rocker ~rm 232. The rocker arm 230 is mounted for rotation on n exten- .
sion of the shaft 164 which projeets outwardly from the frame plate 54 and the rocker arm 232 is ~ounted for rota~io~ relative to shaft 62. Cam followers 234 and 236 are located at the other ends of rocker arms 230 and 232 respectively and engage cams 238 arld 240 respectively which are mo~lted on snd driven by cam shaft 136. Thus, it will be seen that one full rotation of the cam shaft ~36 will move the folding arms inwardly from the position ~hown to the position shown in Figure 9 and outwardly once again to the position shown in Figure 8.
From the profile of ~he cams 238 and 240 it will be :~ appaxent that in each complete cycle there ~re times when the '~
arms are in their outermost position and theI~ innermost position I .
and there are also times when the arms are in an intermediate position. It will also be undexstood that the position of the cams on the shaft 136 is such that the :Lower folding arm operates to fold the lower side panel inwardly before the upper folding arm operates to fold the upper side panel inwardly.
A mechanism is also pro~ided for folding the portion of the we~ ~hich projects outwaraly from the bottom wall forming portions into an ou~wardly overlying relationship with respect to the side walls~ A major portion of this mechanism has previously , been described in describing the operat.ion of the knife mechanism used for forming the slits 40. As previously indicated, a roller 212 is mounted at the outer end of link arms 208 which are pivot able about the axis of the-shaft 206. It is the movement of the roller 212 from its outwardly spaced position shown in Figure 9 to its inner position shown in Figure 10 which folds the portion 30 of the web-which-pro3ects--from the bottom wall panel into an out-wardly overlying relati~nship with respect to the side wall of ~ , the bag. The mechanism for effecting movemen~ ~f ~he roller 212 between the positi~n shown in ~igure 9 and Figure 10 of the draw-ings includes a connecting rod 242 which has one end connected to the shaft 210 and its other end connected to a rocker arm 244.
A cam ~ollower 246 is located at the o~her end of ~he rocker arm 244 in engagement wi~h:~a cam 24B. A connec~ing rod 243 is con-nected to the shaft 210 associated with the other roller 212 -~ and is pivotally connected to a lever arm 245 which is secured to the shaft 62 for movement with the shaft 62 as is the rocker arm 244. A return spring 250 extends between one anm of the rocker arm 244 and a support pin 252 which is secured to the frame. The return spring 250 serves to urge ~he mechanism supporting rollers 212 to the outwardly spaced position illustrated in Figure 9 of ~he drawings.
Dischar~e Mechanism ~aving described the elements of the mechanism required to fold the web to form the bag about the former, the discharge mechanism for discharging the bag from the former will now be described.
As shown in ~igures 7 and 8 of the drawinys, rectangular shaped opening 254 is formed in the former plates 58 and 60 ad-jacent the bottom wall forming edge thereof. With reference to Fi~ures 8 and 11 of the drawi~gs, it will be seen that a roller 256 is mounted inwardly of each of the plates 58 and 60 and has a peripheral edge portion projecting through the opening 254.
The rollers 256 are keyed to support shaft 258 which is j~urnalle~
in a support bracket 260 which is mounted on the free end of a support arm 261 the other end of which is mounted on a bracket 263 which is secured to the adjacent former plate (Figure 8).
The arms 261 a-re-sufficiently flexible to enable the rollers 2S6 to be self-aligning with respect to the roll~r 212 and to accom-moda~e limited movement of ~he rollers 25S away from and towards the rOllers 212. The rollers 256 are urged away from one another by an expansion mech~nism 265 which includes shats 267 and 269 wlli ch are telescoped one wi thin the c:~ther and comDression sprin~
273 which reacts ayainst heads 271 at the free end of each shaft Z67 and 269~
A drive pulley 262 is unted to drivingly engage each shaft 258. The pulleys 262 are each driven by a drive belt 264 which, as shown in Figure 10 of the drawings, extend around pull-eys 2~6 which are drivingly mounted on 5hafts 268~ The shafts 268 are supportea by the frame for rotation about their axes, the supports for the shafts 268 being eliminated from Figure 10 of thé drawings so as to avoid o~er complication of the mechanism ill~c~rated. Gears 270 are mounted on each shaft 268 to mesh with ~iie gears 178 and 180 which are rotatably driven by shaft 130 as previously described. Thus, the disc~arge rollers 256 are driven !~ :
by the motor 100 through the power train ~reviously described. I
~ t W~ 11 t however be apparent that the discharge rollers 256 are onl~ ~pable of drivingly engaging the bag when the ~olding rol-20 lers 212 are l~cated in the inner po~ition illustrated in Figure 11.
As a bag is discharged from the former the crease lines 39 are formed by the rollers 212 bearing against the edges of the former. I~ith reference to Figure 11 of the drawings, it will be seen that each of the rollers 212 has an angularly inclined shoulder 215 at each end thereof projecting radially outwardly to a cylindrical surface 213 of greater diameter than that of the main boay of the roller 212. A resilient collar 211 and a flQx-ible lip Z17 are mounted in a recess formed in the roller 212 and cooperat~ with ~he side edges 64 ~nd 68 of the former to form a ; sharp crease along edges 39 without damaging the bag as ~ is discharged from the former.

:

Unwindin~ Mechanism To permit a ~hangeover from one coil of bag forming material to ano~her, two unwinding support shafts are provided. .
As shown in Figure 12 of the drawings, one of the support shafts is identified b~ ~he reference numeral 290 and ~he other is iden--tified by the xeference numeral 292. These shafts may be sup-ported by the frame or they may be mounted on self-supportiny support stands. At the input end to the former, a xoller 77 is mounted for xotation on the outer end of a pair o~ lever arms ~` 10 294 (shown in broken lines). The other ends of the lever arms 294 are pivotally mounted for rotation about the axis of a shaft 296. A control lever 298 projects outwardly from the shaft 296 and is operable to move in the directions of the arrows shown in Figure 12 to move the roller 77 between a position in which it will cooperate with the roller 78 to drive a web therebetween or a position in which it will cooperate with the roller 79 to drive a web therebQtween. In the embodiment shown in Figure 12, a web 12 is being unwound from a first coil l0 around guide rol-lers 300 and 302, along a platform 304 to be driven by pinch rol-ler 78 and pressure roller 77. When all of the web has been un-wound from the coil 10, the control lever 298 may be moved to a position in which the pressure roller 77 engages the web 12a and begins to unwind the web 12a from the coil 10a around guide rol-lers 299, 300a, 302a. Thus, it is possible to replace a coil without disrupting the operation of the bag forming machine.
Method of Operation - The bag forming machine aescribed above can be set up so as to proceed from the starting configuration illustratea in Figure 12 of the drawings to the point where a bag is discharged ',~ in an open configuration by following one or other of several sequences. The following description of the method of operation ~ .

refers to one such sequence i~ which after an initial set up, the bag forming machine comes to ~est in a position ready to effect an immediate discharge of a bag in the open configuration from the former and to si~ultaneously commence the forming of a sub-sequent bag to the configuration of the bag whichis in the process of being discharges~
Thus, with reference to Figure 12 of the drawings, when the two rolls of bag forming material have been mounted as pre-vious'-~ described and the control lever 298 set to unwind ~he first web, the operator will activate the bag forming mechanism, gen-erally by means of a foot pedal or the like, to cause the motor 100 to drive the power train. Initially, the aischarge rollers 256 will be driven while the feeding conveyors 82 and the pinch r-llers will be retained in a stationary condition by the solenoid ~ontrolled clutch 124. After a period of time sufficient to per-mit dischar~e of a bag from the former, if a bag had been located on the former, the feed mechanism will be activated as will be cribed hereinafter to feed a web around the former.
The knife 84 is then activated to cut the bag ~orming lenl~rh from the web and the folding arms are also activated to fold the side forming panels inwardly to the overlapping position.
The power to the motor 100 is then interrupted so that the mech-an~ :~ remains in a l'holdl' position in which the web is folded to tl required bag configuration but the seal i5 not totally made until the bay is discharged.
The sequence of events is best illustrated by reference to Figure 13 of the drawings in which the outermost track 300 diagrammatically illustrates the operation and timing of the dis-charge mechanism and the cutter mechanism for cutting the slits 40. The second track 302 diagrammatically illustrates the timing and operation of the main cutter blade and the movement of the ~ _ ", j ~, i,.

gates 150 between the open and closed pOSitions~ The track 304 illustrates the timin~ and operation of the feed mechanism and the operation of ~he lower fold arm.
Track 306 illustrates the timing and operation of the upper fold arm.
As previously indicated, after the initial set-up, ~he machine is in the position in ~hich a bag is substantially fu~ly formed on the former but is not totally sealed. This position ; is represented by the zero degree ~O) marking on Figure 13. ¦~
The sequence of events in the operation of the machine can best be ~scribed by proceeding to read the dia~ram illustrated in Figure 13 in a counterclo~kwise direction. ~hen the operator activates the mechanism which is in effect a demand for the pro- ¦
duction of an open bag, power is supplied to the motor 100 and as s~own ~etween the 20 and 40 positions of Figure 13 the dis-ch~-ge roller 212 is moved to its innermost position in which i-~ will press the bag into driving engagement with the discharge r~ rs 256. Simultaneouslyl the gates 150 will move to the open pO~ Gn . As shown in track 304, the upper and lower folding arms will remain in their lowermost position for a short period of time after ~he initial movement of the discharge rollers 212.
This .~eriod of time is sufficient to enable the discharge rollers to ~ ve sufficiently close to the sides of the bag to prevent the sici~ ~orming panels moving away from the former. Thereafter, the Uppf r and lower folding arms will be withdrawn to an inter-mediate position which they assume at the 40 position. Between the 40 position and a position at about 130, the discharge mechanism is fully operative and the gates 150 are fully open and a bag is in the process of being discharged and sealed by ~30 engagement of the seal line between rollers 256 and 212. At about 130 displacement`, the upper and low~r fol~ing arms are raised ~ ,, ;

clPar o~ the guide track o~ the iormer so as to be out of the path of t~e feed o the next bag. At the 160~ displacement posi-tion, the ~ully ~onmed ~ag has been discharged from the former and the rollers 212 begin to move away from the rollers 256 ~nd conti~ue to do so until about the 200~ mark. At the same time, the gates 150 begin to move inwardly to move the guide belts 140 and 142 to a position to guide the web around the former. At about 180 displacement, the solenoid ~alve 120 is ctivated to release the clutch124 to permit the feed mechanism to operate to drive the unwinding web around the former. The feed mechanism is operational up to about the 255 position whereupon the solenoid valve 120 is again activated to operate the clu~h 12~ to interxupt the power supplied to the feed mechanism. At about the 250 position~ the mechanism which supports the side cutters is acti-vated to move to engage the web and form the slits 40, the slits being completed at the Z80 mark whereupon the mechanism is part- I
ially retracted. As shown with reference to track 3Q2, the main ~;
cuttcr blade mechanism is activated bet:ween the 280 mark and the 3Ano mark to cut the bag forming length rom the continuous web. Simultaneously, between the 280 mark and khe 320 mark, the lower fold arm is moved to its innermost position thereby folding the lower side wall forming portion inwardly about the for~ex. At about the 300 mark,the uppér fold anm begins to move inwardly and continues to do so to about the 350 mark to fold the upper side wall forming portion inwaraly to an outwardly overlying relationship with respect to the lower side wall form-ing portion and thereafter the mechanism comes to rest at the p position. This is achieved by the cam 282 activating the switch 286 to disrupt the power supplied to motor 100 causing the mech-anism to come to rest in the holding position.
~ . , ~.~b.~ "

From the foregoing, it will be apparen~ that the present invention provides a simple and efficient apparatus for forming a bagO ~hile it is to be understood that various modifications of the apparatus will be apparent to those skilled in the art, there are a number of fea~ures of the apparatus described in the preferred embodiment which are particularly advantageous.
An example of a particularly advanta~eous featur~ of the app~-~tus of the present invention is the fact that the mechanism is l~ ely mechanical so that it is capable of being serviced by n a mechanic having only a basic knowledge of mechanical mechanisms.
Furthermore, all of the mechanical controls are effected from a single cam sha~t.
In tests carried out with a test model of this apparatus, difficul~y was experienced in discharging the bags from the former.
The d-,-ficulty appeared to result from the fact that while the disc'.,.--Lge rollers were initially required to engage the sides of th~ bag which are several layers thick, as sho~ in Figure 6, the -- r~lers subsequently move to engage the web of the thickness of the ~erlap. Initially, the discharge rollers 256 were mounted ~20 on iixed bearings located on the former plates. With this con-struction, although a bag could be formed without difficulty, the appearance of the ~ag was, on occasion t adversely affected by elative movement occurring between the opposi~ely disposed sit~e panels at the overlap. It was found that by mounting the rollers 256 50 that they are able to float and are self-aligning, this difficulty has been largely overcome.
A further difficulty which was experiencea in preliminary tests was in maintaining the overlapping relationship at the side walls until the bag was fully discharged. It was found that there was a tendency for the overlapping edges to move away from one another when the discharged load was applied between the dis-.. . . .. .

!
charge rollers 212 and 256. This difficulty has been overcome by the simple expedient of providing the spring biasing fingers 219 on each of the folding arms 218. The fingers 219 press against the side wall forming portions of the bag above the plane of the overlap so that when a discharging load is applied in the plane of the overlap, the movement vf the bag in the area under-lying the pressure fingers 219 in a direction towards ~he dis-charge is retarded, thus tending to direct th~ overlapping edges inwardly toward the overlapping relationship.
The edges 64, 66 and 68 of the former plates 58 and 60 perform the dual function of providing a guide rail about which an unwinding web may be directed and a folding edge about which the side wall forming panel5 may be folded inwaxdly. The guide - rollers 72 and 74 provide an arcuate surface about which to bend ~he web as it is driven along the guide path without weakening the web as a result of bending thereabout. The endless conveyors 8~ rreferably have a ridged underface which engages ridges formed in the base of the various groo~es in the ~arious rollers about which they extend so that the rollers are positively drIven.
~t will be noted that while many of the elements of the bag forming machine are movable, the former is itself stationary.
One of the advantages to a stationary former is that the space oc upied by the machine need be only slightly greater than the ove_all proportions of the former. In many applications such as the installation of a device of this type in a chec~-out counter, space is at a premium and it is, therefore, important to minimize the size of the bag forming machine. In preliminary work, the applicant did develop machines in which the former was movable.
~lowever, such machines were quite large by reason of the need to provide space for accommodating movement of the former.

~_ I

g~$P~ ~

The usP of flexible belts to form the outer guide members considerably simplified ~he construction of ~he outer guide.
Considerable aifficulty was experienced in attempting to devise a mechanism which w~uld provide a guide for guidina the web around the bottom wall forming portion of the former but which would also permit discharge of the formed bag from the stationary former. This difficulty was overcome by using the flexible guide belts 140 and 142 and extendiny these belts around the corners formed at the bottom wall forming portion and mounting the outer end thereof on the movable yates. By combining ~he discharge mechanism with the sealing mechanism, the present apparatus per- ¦
mits the rollers which are used to engage opposite sides of the bas to discharge it from the former to drive the discharging bag so that the overlapping edges of the web along which a seal is to be formed are driven between the discharge rollers so that ,~
the overlapping edges are pre5sed together by the discharging rol~ers to form an efficient seal. Simultaneously with the discharging, a crease line is formed between one of the discharge rollers 212 and -the edge of the former so that when the bag is ~20 discharged from the former it will auto~tically assume and retain th^ ~pen configuration and will have no memory tending to urge t;.- bag towards a lay-flat or knock-down configuration.
In the method of forming the square bottom bag by means r of the apparatus of the preferred embodimentt it will ~e noted that wh;le the web is subjected to bending about the rollers 72 and 74 to the U-shaped configuration, this bending does not form any permanent crease lines which would weaken the structure of the bottom of the bag. This has the advantage that the strength .. .. .
of the bottom of the bag thus produced is greater than that pro-- 30 duced by the conventional ~ag forming methods in which the web is creased to enable it to be stored in ~ knock-down configuration.

~ ~

7 ~

Tes~s have indicated that ~ square bott~m bag construc~ced by the method described and the apparatus ofthe preferred embodimerlt using a con~en~iorlal paper bag roIl stock of the type con~nonly used for packaging groceries will maint~in its open config~ration , when discharged so that it is open to facilitate loading with groceries or the like.
V~rious modifications vf the present invention will be apparent to those skilled in the art. One modification is illustraked in Figures 14 and 16 of the drawings. As shown in 10 Figure 14 of lthe dsawings, a ~and 22 of a thermosettlng adhesive or a radiation ~nsative adhesive is applied to the outer ace 16 of the web 12 at the marginal edge of the side closure fonning portions 34.. It should 3be noted that no adhesive ban~ is applied to the inner :Eace 18 of the web 120 In order to form a seal, ~he side wall forming portions 34 are folded inwardly so that the marginal edge of the upper side wall forming portion is loca- `
ted in an outwardly overlying relationship with respect to the marginal edge of the lower side wal.l forming portion~ In this - posi~ion, the b~nd of adhesive ~Oa which is applied to the marginal edge portion of the lower side wall orming wall member is in intimate contact with the inner surface of the opp~site side wall forming portion 34. Thereafter, the bottom corner flap 35 is folded inwardly to the position shown in Figure 16.
The critical areas of the heat sensitive adhesive are ~hen acti~ated to bond the overlying portions of the side wall c~osure , members together in ~he configuration shown in Figure 16. It will be noted that the portion of the adhesive band 20 which is located on the external surface of the side wall after folding to ~he position shown in Figure 15 ser~es to secure the end t 30 flap 35 in the inwardly folded position~ Thus, it will be seen ,~

. ", ,, ~

,~ 'f f~

that a bag may be constructed in which the adhesive is in the form of a thermosetting adhesive or an adhesive of a type which i5 ac~i~a~ed by radiation of one form or ano*her. A bag may be cons~ructed in this confi~uration in ~he apparatus pre~iously de~cri~ed by the addition of a heat sealing element upstream from the sealing and dispenser rollers. Alternatively D the sealing rollers may be heated to an extent suficient to cause the bands of adhesive 28 to be activated during discharge of the bag from the *ormer. i`
While it is possible to use adhesives which are acti-~ated by one form of radiation or another su~h as thermal radia- ~.
tion, there is a substantial advantage to the use of the pressure sensitiYe adhesive of the t~pe described in the embodiment illus- .
trated in Figures 1 through 6 of the drawings. The pxessure '~
sensitive adhesive does not reguire a radiation or heating device to be present in the bag forming apparatus and, provided adequate pressure is applied, it is not necessary to provide a minimum dwell time in order to achieve the required adhesion.
On the other ~and, the use of the heat sensitive or radiation sensitive adhesive may serve to elimunate the need to pro~ide ~he adhesive at both the inner and outer faces of the web so -~ that there may be a saving in the amount of adhesive used.
The present invention provides a method and apparatus for manufacturing a bag which is discharged in an open configu- .
rationO The method and apparatus are so simple that the opera~ion ' - of making a bag may be carried out by the end user rath~r than by a converter. Thus, the packer may simply stock a supply of roll stock and manufacture bags as required from the roll stock.
This reduces the volum~ of material which must be stocked by the packer.

In the orégoing disclosure, reerence has been made to the fac~ that the cutter mechanism for severing the bag iEorming length from the continuous web include~ a cutter 3blz~de which has a plurality of V-shaped teeth which are driven direct-ly through the web. As pre~iousl~ indic:atea, this mechanism has the advantage that it requires a minimal amount of spac:e.
A further a~l~vantage of this ~néchanism is that in cutting through the web, thl~ teeth fo~m an irregular edge aoross the web. This is in cont~ast to the very 5harp edge which is fQImed by a knife 10 such as a guillotine. This is extremely impc~rtant in the manu-fac~ture of bags which are to be manually loaded in which the operator is re~uired to pass his hand or ann through the open end of the ~ag duriny the loading operati3n.. A sharp eage on a bag such as a grocery bag would represent 2 substantial hazard to the packer~ .
In the preceding disclosur the advantages to be de-ri~ed from the fact that the bottom of the bag is not creased to the extent required with conventional bags have been discussed

2~ ~ e gth. In the conventio~al knock-down paper bag it is nece-20 ssary to form a 360~ fold along the edges of the bottom wall ; p,~ l so ~hat the bag can lay flat for storage purposes. ~his 360 fold causes a considerable numbe~ of the fibres of the body of a ~b of paper material to break.thus weakening the paper bag. In certain applications it may be desirable to form a fold line between the front, back and bottom walls of a bag ~onstructed in accordance with an embodiment of the present invention to assist in the formation of a fla~.bottom wall which will pro~ide a stable support or the empty bag. In the con-struction of a bag according to the met~ods described herein-beore it is only necessary to form a 90 fold between ~he front, bottom a~d bac~k walls as the bag is disc:harged in the open COn~Eiguration ~ thu5 the folding does not damage the fibre structure of the web to the extent required to obtain a lay flat conf iguration .
These and other advantages of the method and apparatus of the present invention will be apparent to those skilled in the art.

Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of forming a square bottom bag from a bag forming section of a web of bag forming material which has a length in a first direction and a width in a second direction at right angles to said first direction and which includes a main panel extending in said first direction and bounded on either side by a side closure forming panel comprising the steps of :
a) driving said web in said first direction and bending said web upon itself across its width, as it is driven in said first direction to an open U-shaped configuration in which said main panel forms unitary, serially connected, front, bottom and back walls which are closed in the configuration which they will assume when said bag is open;
b) supporting said main panel in said open U-shaped configuration;
c) folding said side closure forming panels toward one another to an overlapping relationship and securing said side closure forming panels with respect to one another in said overlapping relationship to form side walls of a bag.

2. A method of forming a square bottom bag from a web of bag forming material which is longitudinally elongated in a first direction and has a main panel extending in said first direction bounded on either side by a side closure forming portion comprising the steps of:
a) driving said web in said first direction into a bag forming station and bending a first bag forming length of said web transversely upon itself as it is driven into said forming station to an open U-shaped configuration in which portions of said main panel are disposed opposites and are spaced from one another in the configuration which they will assume when said bag is open;
b) supporting said main panel in said open U-shaped configuration;

c) severing said d first bag forming length from said web;
d) folding said side closure forming panels toward one another to an overlapping relationship and securing said side closure panels with respect to one another in said over-lapping relationship to form side walls of a bag; and e) discharging the thus formed bag from said forming station in an open configuration.

3. A method of forming a square bottom bag from a bag forming section of a web of bag forming material which has a length in a first direction and a width in a second direction at right angles to said first direction and which includes a main panel extending in said first direction having front, bottom, and back wall forming portions serially connected to one another and side closure forming panels extending laterally from said front, bottom and back forming portions, comprising the steps of:
a) bending said web Upon itself across its width to an open U-shaped configuration in which the front and back wall forming portions of the main panel are spaced from one another by the bottom wall forming portion, b) supporting said front, bottom and back wall portions on a stationary mandrel in said open U-shaped configura-tion, c) folding the side closure forming panels extending from the front and back portions of the main panel inwardly toward one another to an overlapping relationship and thereafter folding the side closure forming panels projecting from the bottom wall inwardly of the mandrel to outwardly overly the said closure forming panels of the front and back wall and securing said side closure forming panels in said overlying relationship to close opposite sides of the bag, and d) discharging the thus formed empty bag from the mandrel in an open configuration.

4. A method as claimed in Claim 1, 2 or 3 in which the bag is creased along the fold lines connecting the side closure forming panels to the front and back walls of the main panel after securing of the side closure forming panels to form a right angle crease tending to urge the bag towards to the open configuration.

5. A method as claimed in Claim 1 wherein said side closure forming panels include first panels projecting laterally from said front and back walls of said main panel and second panels projecting laterally from said bottom wall, said first panels being folded inwardly as aforesaid to said overlapping relationship and thereafter said second panels being folded inwardly to be secured in an outwardly overlying relation-ship with respect to their associated first panels.

6. A method of forming a square bottom bag as claimed in Claim 5 where each of said second panels is cut along a pair of spaced cut lines extending inwardly from the side edges of the web centrally of the length of each second panel to form a pad therebetween whereby upon folding of said first panels inwardly as aforesaid said second panels are folded along a fold line extending diagonally between the base of each of said cut lines and an adjacent corner of said bottom panel.

7. A method of forming a square bottom bag as claimed in claim 1, 2 or 3 wherein said side closure forming panels include first panels projecting laterally from said front and back walls of said main panel and second panels projecting laterally from said bottom wall, said second panels being folded inwardly as aforesaid and therafter said first panels being folded inwardly to be secured in an outwardly overlying relationship with respect to their associated second panels.

8. A method as claimed in Claim 1, 2 or 3 wherein said side closure forming panels include first panels pro-jecting laterally from said front and back walls of said main panel and second panels projecting laterally from said bottom wall and wherein said web is creased along the fold lines connecting said first panels to said front and back walls when said web is in the required configuration of an open bag to thereby impress a memory on the formed web which will tend to urge the thus formed bag to retain an open configuration to facilitate loading of the bag in use.

9. A method as claimed in claim 1 wherein said web has an inner face and an outer face and marginal edge portions extending longitudinally of the free edges of said side closure panels and wherein said side closure panels are secured by means of a pressure sensitive adhesive of a type which is inactive until two layers thereof are placed in contact with one another and subjected to pressure, a layer of said adhesive being applied to said inner face of said web in the first band extending along each marginal edge portion and a layer of said adhesive being applied to said outer face of said web in a second band extending along each marginal edge portion thereof whereby upon folding of said side closure forming panels as b) first, second and third side panels projecting from opposite sides of said front, bottom and back walls respectively,said first, second and third panels having serially arranged marginal edge portions, c) each second side panel being cut along a pair of cut lines extending inwardly from the free edge thereof to form a tab therebetween, d) a first band of adhesive extending along the full length of said serially arranged marginal edges on the outer face of said side panels, said first band including first and third lengths extending away from each tab on opposite sides thereof and a second length extending across the outer face of each tab, e) a second band of adhesive extending along the full length of said serially arranged marginal edges on the inner face of said side panels, said second band including first and third lengths extending away from each tab on opposite sides thereof and a second length extending across the inner face of each tab, f) said first and third side panels being folded inwardly along their connection with the front and back walls respectively, each of said second side panels being folded upon itself along fold lines extending obliquely from opposite sides of said tabs to an adjacent corner of said bottom wall to form bottom side-edge closure flaps,said first length of said first adhesive band being disposed in a face-to-face bonding contact with said third length of said second band along the full length thereof to close opposite sides of the bag, g) said bottom side-edge closure flaps being folded along their connection with the bottom wall to fold said third length of said first band of adhesive upon itself aforesaid , said first and second bands of adhesive are located in a face-to-face relationship and are subjected to pressure to secure said side closure panels as aforesaid.

10. A method as claimed in Claim g wherein said first and second bands of pressure sensitive adhesive are laterally spaced from one another in each marginal edge portion.

11. A method as claimed in claim 2 wherein bending of said web upon itself is effected around a stationary mandrel.

12. A method as claimed in claim 11 wherein said bag is driven off of said stationary mandrel in its open configu-ration.

13. A method as claimed in claim 12 wherein said web is creased along the fold lines connecting the front and back walls to their associated side closure panels as said bag is driven off of said stationary mandrel.

14. A method as claimed in claim 1, 2 or 3 in which said web is a web of paper.

15. A method of forming a square bottom bag as claimed in claim 2, 3 or 4 wherein the unwinding web is directed along a first generally planar plane in the direction of the longitudinal extent of the web and thereafter along a second generally planar plane which extends perpendicular to the first plane and thereafter along a third generally planar plane which extends substantially parallel to the first planar plane and is disposed in a face-to-face relationship with respect to the first planar plane to form the web to the U-shaped configuration.

16. A square bottom bag comprising;
a) a front wall, a bottom wall and back wall formed from a unitary panel having an inner face and an outer face, said front, bottom and back walls being arranged in an open U-shaped configuration, into a face-to-face bonded relationship securing said triangular-shaped closure panels in an outwardly overlying relationship with the first and third side panels.

17. A square bottom bag as claimed in claim 16 wherein said second length of said second band of adhesive is disposed in face-to-face bonding contact with an underlying portion of said third length of said first band to adhesively secure said tabs in a outwardly overlying relationship with said first and third side panels.

18. A square bottom bag as claimed in Claim 16 wherein said first and second bands of adhesive are com-plementary cohesive adhesive bands.

19. A square bottom bag as claimed in claim 16, 17 or 18 wherein the corners formed between the bottom wall and the front and back walls are rounded and free of crease lines such that the bottom of the bag is not weakened by crease lines.