Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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
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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.
