Note: Descriptions are shown in the official language in which they were submitted.
U~'~l;3
FIELD OF INVENTION
This invention relat~s to roll stock for use in
the manufacture of square bottom bags.
PRIOR ~RT
In the manufacture of bags such as paper bags, it is
cus~omary for the bag to be manufactured by a bag manufacturer
and shipped to the user in a knocked down configura~ion. Despite
the fact that the bags are shipped from the manufacturer in a
knocked down configuration~ the bulk of the bags after manufacture
is generally substantially greater than the bulk of 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:associated with the shipping and
storing of bags in the ]snocked down configuration is greater
than that experienced with the shipping and storing of roll
stock in the form of a coil.
During the manufacture of square bottom paper bags by
the conventional bag forming apparatus, the roll stock is creased
to form a tubular member having inwardly directed side gusset
panels. In the forming of the bottom of the bag, a comple~
series of creases are formed~ Each crease is formed so that
the paper stock will be permanently set at the crease line.
To achieve this permanent crease, it is necessary ~o damage
some of the fibers at each crease line. This has the effect of
weakening the bag along each crease line. In the conventional
manufacture of bags, it is necessary to form crease lines
extending transversely across the bottom of the bags in order
to locate the bags in the lay-flat configuration. Thus,
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in forming weakened crease lines extending across the
bottom 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.
; 5 Panels are produced in the knocked down configura-
tion 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 bagstructurs to the laydown configuration when the bag is un-
supported. As a result, when a bag is opened, it is necessary
to provide a retaining means of some type for retaining the
bag in the open configuration to prevent it from returning
to its lay-flat configuration. Because the bag always tends
to return to its lay-flat configuration, it is difficult for
the users, such 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
mechanically opening knocked down bags and retaining them
in the open configuration. 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 is folded upon itself
to a tubular sleeve configuration with longitudinal side gussets.
The bottom of the bag is formed by a complex series of folding
and gluing operations and, as previously indicated, the
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bottom of the bag is inherently weakened by the various
~olding and creasing operations to which it is subjected.
Furthermore, the side gussets tend to draw the front and
back walls of ~he bag towards one another even wh~n the
square bottom is formed, making it diEficult to obtain
access to the bag without holding the free end in the open
configuration.
While it is customary to manufacture bags from
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 bag making machine is
so complex that the individual skilled in the art would not
consider attempting to apply adhesive to khe 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 the roll to one
another.
The existing bag forming machines are large and
complex and expensive. The machines are specifically
designed to convert roll stock to bags which are discharged
in a lay-flat configuration. The machines have many moving
parts and are designed to operate at high speed. The
machines of the prior art are specifically designed to form
the 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.
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SUMMARY OE` INVENTION
.
~ccordi.ng to one aspect of the present invention,
roll stock for use in tlle manufacture of bags comprises a
longitudinally elongated web of bag :Eorming material having
an inner face and and an outer face, a pair oE oppositely
disposed side edges and a marginal edge portion extending
inwardly from each of said side edges, said web having a
uniform thickness across its full width, said web being
wound into a roll with said inner and outer faces aligned
and in face-to-face contact with one another, a first pair
~; and a second pair of bands of cohesive-adhesive material,
one of said pairs of adhesive bands being applied to and
extending continuously in a straight path along said i}mer
face and the other pair being applied to and extending con-
tinuously in a straight path along said outer face of said
web, one band of each pair being located at each marginal
: edge portion, the bands of said first pair being laterally
spaced with respect to the bands of said second pair so as
: to be out of alignment with one another in successive turns
of said roll such that the successive turns of said roll are
not adhesively secured to one another.
According to a further aspect of the present
inventlon, the roll stock as described above is formed such
that the first pair of adhesive bands extend inwardly from
: 25 each side edge of the web and one o:E said second pair of
bands is spaced inwardly from said side edges a distance
which is greater than the width of said inner bands.
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.
.
According to yet another aspect of the present
invention, -the roll stock as described in the preceding
paragraph is provided wherein the bands of the first pair
of bands of adhesive are substantially wider than the bands
of the second pair to provide an enlargecl target area for
contact with an inner band.
It is yet another object of the present invention
to provide an improved roll stock for use in the manufacture
of square bottom bags.
PREFERRED EMBODIMENT
The invention will be more clearly understood
after reference to the following detailed specification
read in conjunction with the drawings, wherein
Figure 1 is a pictorial view illustrating a
first step in the forming of a square bottom bag from
roll stock;
Figure 2 is an enlarged detail of the portion
of the web to Figure l;
Figure 3 is a pictorial view illus~rating the
2G folding of the sides of the bag inwardly upon one
another;
F.igure 4 is a pictorial view similar to Figure
3 showing a bag in ~e form in which it is discharged from
the bag forming machine in an erect configuration;
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: Figure 5 is a sectional view along the line
5-S of Figure 4;
Figure 6 is a sectional view along the line
~ 6~6 of Figure 4;
: 5 Figure 7 is a partially sectiorled pictorial
; view of a bag forming machine constructed in accordance
: with an embodiment of the present invention with certain
elements removed for convenience of illustration of the
former about which the web 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;
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Figure 9 i5 a view si~ilar to Figure 8 showing a first
step in the closure of the sides of the bag around the former;
Fi~ures 9a and 9b are partially sectioned views
illustrating the m~chanism for severing $he web to form an
anchor tab on the side portions projecting from the bottom wall
of the web;
Figure 9c is a sectional view taken along the line
9c of Figure 9b;
Figure 10 is a view similar to Figure 9 illustrating
the apparatus moving to the position to permit discharge of
the bag therefrom in the open configuration;
Figure 11 is a sectional view along the line 11-11
of Figure 10;
Fi~ure 12 is a diagrammatic sectional side view of
a bag forming machine of the present invention showing the
two positions of the 1exible guide belts and the mounting
of two rolls of paper stoc~;
Figure 13 is a diagram illustrating the timing of
the various functions o~ the apparatus;
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Figure 1~ is a pictorial side vi~w of a ~ag forming
length of web similar to Figure 1 illustrating a modiication
in the form of an al$ernative type of sealing means;
Figure 15 is a pictorial side ~iew showing the m,nner
in which the side wall forming portions of the member o Figure
14 are folded inwardly to overlapping position; and
Figure 16 is a ~iew showing the folding of the ~nd
: flap of Figure 15 inwardly upon the side walls to t~e closed
position.
~igures 1 to fi of the drawings serve to illustrate
a metho~ of making a bag, a bag structure and a roll st:ock for
use in making a bag in accordance with various aspects o the
; present invention. r
Roll Stoc~
~ In Fisure 1 of the drawings, the reference n~meral 10
: refers generally to a coil of a material such as paper suitable
for use in the manu~acture of a paper bag. The coil 10 consists
: of a continuous web 12 which is wound around a core 14. The web
: has an outer surface 1~ and an inner sur~ace 180 A continuous 20 band of adhesive 20 is located on the upper sur~ace 16 in a band
which is spaced laterally inwaraly from each side edge of the web. .
band 22 o~ a similar adhesive is applied to the inner face 18 l~
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in a continuous band which is located between each side edge of
the web and its ~ssociated band of adhesive 20 The adhesive
bands 20 and 22 are laterally spaced from one another so that they
do not come in contact with one another when the web is wo~nd
upon itself in the coil form. The adhesive is of a type which
will not bond to the material from which the web is manufactured
but will bond to another layer o~ the same adhesive such that if
the adhesive in the band 20 is placed in contact with adhe~ive
in a band 22, a bond will be formed therebetween.
The use of roll stock of the type described above is
important in the manufacture of bags according to the method of
the present inven~ion 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 of bag
forming stock, it is possible to eliminate adhesive applying
mechanisms from a bag making mach~ne and this has the advantage
of simplifying the mechanism which is required and simplifyin~
the method of operation of the bag forming machine. By reason
of the f~ct that the 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 adhesive which are placed
in contact with one another merely by pressing the bands one
against the other with no need to effec~ a curing of the bond
before releasing the compressive forces applied thereto to effect
the bond.
A Co-A~hesive suitable for use in accordance with the
present invention is manufactured by FINDLAY INC.
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and sold under the trade marX NIPWELD 207-939. Other similar
co-adhesive~ are availab~e from Industrial Adhesives Limited
and sold under the trade name L3108
Method b~ Forminq Ba~s
As shown in Figure 1 of the drawings, the web 12 i~
unwound from the coil 10 an~ is driven in the direction of the
arrow A. The unwinding end is driven along a U-shaped guide
path as will be described hereinafter in detail with reference
to the apparatus. As the web is guided along the U-shaped guide
10 path, it is caused to bend upon itself around a first rounded
corner in the area 23 and thereafter around a second corner in
the area 24. It is important to note that, 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 length of web to ~orm one bag is
: then severed from the roll along the line 26. The broken lines
28 appearing in Figure 1 of the drawings serve to separate the
panel 32 which forms the main panèl of the web from the side
2û closure forming portis:ns 34.
The main panel 32 consists of a bottom w~l panel 36
~; ana 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 420
As shown in Figure 3 of the drawings, the side wall
- forming portions 34a which project fxom 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 inwar~ a~ again the
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443 '
portion 34d folds along a fold line 44 extending from the base of
the tab 42 to an adjacent corner of the bottom wall. When the
side wall fo~ing portions 34c are folded inwardly, ~h~ adhesive
bands 22 which axe located on the inner face thereof are placed
in face to face contact with ~he adhesive band 20 on the exterior
surface of the side wall forming portion~ 34a and are pressed to-
gether to form a permanent bond therebetween. Similarly the
portions 34b and 34d and the tab 42 are o1ded into a ~ace-to-
face relationship with the remainder of the side walls as shown
in Figure 4 ana are secured in the folded position by reas~n of
the fact that the adhesive band 20 is folded upon itself and is
thereby bonded to it9elf and the adhesive band 22 of the inner
face of the tab 42 is placed in contact with a portion of the
underlying adhesive-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 ~ront and back walls
38 of ~he bag are formed fxom a continuous web and, as shown in
Figure S, the corner 37 formed between panels 36 and 38 is rounded
so that the bottom is not weakened by the bending of the web in
~he forming of the web to the U-shaped configuration.
It will be noted that none of 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-
aftex, a crease may be formed along the longitudinal side edges
3g which will serve to retain the bag in ~he open configuration
when it is removed from the ormer on which it is fonmed. Thus,
the bag constructed in the manner described above has no "memory"
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
1~ 3
an open con~igurati~n which will facilitate loading of the bag.
Wi~h reference to Figure 1 of the drawings, it will be
seen that the irst step in the method of formi~g the bag comprise~
driving the web longitudinally of itself in a first direction and
bending the web as it i5 driven longitu~inally of itsel~ to an
open U-shaped configuration. Thereupon, as illustrated in Figure
3 Of the drawings, the main panels 32 are supported in the open
U-shapea configuration and the side closure fnrming panels are
~olded toward one another to locate the adhesive bands at the
marqinal edge thereof in an overlapping relationship and ~hereby
secure the side walls in the inwardly folded position. Thereafter
the flap.~ which project rom the bottom wall are folded inwardly
- into a face-to-face relationship with respect to the side walls
to be adhesive~y secured as shown in Figure 6. The bag forming
length, having previously been severed from the coil, is dis-
charged in the open configuration shown in Figure 4 without any
~olds or creaseC which will encourage it to move to a knock-down
or lay-flat configura~ion.
Several modifications of the bag and its method of .-s
2n manufacture will be apparent to the individual skilled in the artO
For example, the side wall forming portions projecting from the
bottom wall 36 may be folded inwardly before the side wall form-
ing portions 34a and 34c are folded inwardly. In this mDdifica-
ti.on, the adhesive band 20 extending across the outer surface
o~ the tab 42 woula engage the adhesive band 22 on the inner :
face o~ 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 b~g.
: A~paratus
,~ _
A machine for forming a bag is illustrated in Figures
7 to 12 of the drawings~
Fo r and Web Fee~in Belts
rme _ _ g
With reference to Figure 7 of the drawings, it will be
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seen tha~ a mandrel of former 52 i~ supported between p~ates 54
and 56 of a fram~ in a gen~rally horizontal plane. The former
52 consists of former plates 58 and 60 which are supp~rted on
arms 62 projecting from the plates 54 and 56 of the fr~me. The
former plates 56 ~nd S8 each have a bag forming portion at one
end thereof which has a first folding edge 64, a second foldi~s 1:
edge 66 and a third ~olding edge 68. The for~er plates 58 and 60 f
are spaced from one another a distance substantially equal to the
width of the front, bottom and back panels of a bag to be formed
thereon. The forl~r plates 56 and 58 are spaced from one another '~
by means of a plurality of spacer sha~ts on which guide rollers
are mo~ted. A first guide roller 70 extends transversely between !
the plates 58 and 60 adjacent the input end of the guide pa~h,
the inner p~riphery of which is joined by the olding eages 64,
66 and 68. A second guide roller 72 extends transversely between
plates 58 and 60 at the corner ormed between forming edges 64
and 66 and a third guide roller 74 ex*ends between the pla~es 58
and 60 at the corner formed between forming edges 66 and 68. A
~ourkh guide roller 76 t 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 ext~nd
around the first, second, third t fourth, fifth and sixth guide
rollers. The fifth guide roller 78 also acts as a drive pull~y
ior driving the belts 82 around the former and is formed with
teeth in the pulley recess to drivingly engage the teeth of the
belts 82. In extending between the first and second guide rollers
70 and 72, the conveyor belts 82 extend along the guide path in
substantially the same plane as the first folding edges 64. Simi-
larly, in extending between the second and third guide rollers
and in e~tending between the third and fourth guide rollers, the
conveyor belts 82 extend in the planes of the second folding
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~ ges 66 and the third foldiny edges 58, respectivelyv so that
as will be described hexeinafter the belts 82 m~y s~rve tD ~ri~e
an unwinding web ~round the foxmer~
~eb Cutting Mechanism
In order to sever a bag forming length of web from the
endless coil of web material, a cutter assembly i~ provided be-
tween the fifth and fixst guide rollers 78 and 70. The cutter
assembly consists ~f a cutter blade 84 mounted to reciprocate
vertically between a pair of guide plates 86 and complementary
cutter elements 88 which are spaced above the guides 86 to limit
upward movement of the web to facilitate cutting of the web by
the cutter blade 84. The complementary support elements ~8 are
carried by arms 90 which depend ~rom a beam 92 which extends trans-
versely between plates 54 and 56 of the frame. The cutter blade
84 has extension sprinys 94 at either end thereof secured to pins
96 carried by platPs 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 ~hey can be driven directly through the web
without any later~l movement being required. This is of consid-
erable importance as it enables the drive mechanism for the cutter blade to be in the form of a simply vertically reciprocating
lever.
The operation ~f the cutter blade mechanism is best il-
lustrate~ in Figure 7 of the drawings wherein it will be seen that
~utter blade 94 is supported on a cross bar 126 which is mounted
on the end of a rocker arm 128 which is in turn mount~d to rock
on shaft 130 which extends between former plates 58 and 60. A cam
follower 132 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
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shaft 130 to raise ~m d lower the cutter blade 84 as required.
Power to Feed Conveyors
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The conveyors 82 are driven during the portion of the
bag manufacturing cycle that is employed tv feed a bag-forming
length around the former S2 to the U-shaped configuration. The
conveyors 82 are stationar~ when the folding of the sides of the
web take place and when the bag is being discharged from the
~ormer.
The power source for the bag-forming machine is a motor
100 which drives a sprocket 102 through a reduction gear unit 104.
The sprocket 102 drives a chain 106 around sprockets 108 and 110.
The sprocket 108 i5 keyed to a shaft 112 which is connected through
a clutch 124 to a shaft 113 on which a ifth guiae roller 78 is
mounted to be driven thereby. When the clutch 124 is released the
shaft 113 is coupled to the shaft 112 ana is driven thereby. When
the clutch 124 is engaged the shaft 112 is rotatably driven while
~Xe shaft 113 remains stationary. The operation of the clutch is
regulated by a solenoid valve 120 which has arm 122 pro~ecting
outwardly therefrom to engage a control flange extending from
the clutch. When 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 ~he arm 122 i5 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 roller which
cooperates with the second pinch roller 79 mounted on shaft 114. ',
A gear 116 on shaft 113 is meshea with the gear 118 on
shaft 114 and serves to rotatably drive the shaft 114 which in
turn rotatably dri~es the pinch roller 79. The pinch rollers
78 and 79 must be ariven for a period of time sufficient to cause
the unwinding web to be driven around the former to the U-shaped
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~on~iguration shown in Figure 8. The period of time during which
the feed conveyor mechanism is operably driven is contr~lled by
a cam 280 which is mo~nted on shaft 136 which engages a control
switch 284 (Figure 10). The contro~ switch 284 controls the opera-
tion of the solenoid 120 so that when the control switch 284 is
enga~ed by the 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 2~0 moves out of engagement with the control switch
284 the solenoid 120 releases the arm 122 which moves into engage-
mell~ with the clutch 124 and disconnects the driving engagementbetwe~n the shafts 112 and 113 so that the conveyors come to rest.
Guide Around Former
While the formex 52 serves to provide an intenlal guide
and support for the web and the conveyor 82 serves to provide a
drive mechanism for driving the web around the former, i~ will be
apparent that the web will not ollow the contour of the former
unless a ~uide mechanism is provided for engaging the external
surface of the web and guiding it around the former. :
t~ith 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, ana along
the second support face includes a first pair of flexible guide
~elts 140 ana a second pair of flexible guide belts 142. The
~ elts 140 and 142 are located directly outwardly ~rom the conveyor .
belts 82. The leading end of each belt 140 is secured to a bracket
144 which is mountea on the transversely extending member 92l ad-
justment being provided by a longitudinal slot 146 provided in
the bracket 144. Similarly one end of each guide belt 142 is
moun~ed on a bracket 144 which is secured to a transverse member
of ~he frame lnot shown). Brackets 146 are mounted on transverse
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support member 14B and extend toward the belts 140 and 142 and
are spaced from the brackets 144 and serve to maintain a substan-
tial length of each belt 140 and 142 in the plane of i~s associated
run of the conveyor 82. The other end of each ~elt 140 i5 mounted
on a bracket or gate 150 and the other end of each belt 142 is
mounted on a bracket or gate 152 (Figure 12)o The gates 150 and
152 are pivotally mounted on shafts 154 and 156, respectively, to
pivot between the closea position shown in solid lines in Figure
12 and the open position shown in broken lin~es in Figure 12.
-10 When ~he flexible belts 140 and 142 are in the closed p~sition
shown in solid lines in Fi~ure 12, each ~elt extends around a
corner of ~le former to form a substantially continuous guide
path around the former. When the guide belts are in 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 mo~ing the guide belts between the
open position and the closed position is illustrated in Figure
10 of the drawings. To a~oid over complication of the drawings,
20 only one gate opening mechanism is illus~rated~ However, it will
: be understo~d that the mechanism for moving the gates 150 and
that used for mo~ing the gates 152 is identical, one beîng located
above and the other being located below the former. The mechanism
which is illustrated in Figure 10 includes a lever arm 158 which
is secured to the shaft 154 on which brackets 150 are mounted.
The other 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 is pivotably connected to one end of a rocker arm lS2~ The
rocXer ar~ 162 is mounted to pivot on shaft 164 which extends
from frame plate ~4. A cam follower 166 is mounted a~ the other
end of the rocker arm 162 and is positioned to engage a cam 1~8
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which is mounted on shaft 136. The main lobe of the cam 168 serves
to retain the rocker arm 162 in the position shown in Figure 10
which hol~s the gates 150 in the open position shown in Figure 10
When the cam 166 is rotated, the rocker arm 16~ will pivot about
the shaft 164 to move the brackets 150 between ~he open position
shown in Figure 10 and the closed position shown in Figure 12.
M~in Cam Shaft
The shaft 136 is ~he main cam shaft from which the prin-
cipal mec~anical mechanisms of the machine are controlled. The
drive mechanism which rotatably drives the cam shaft 136 will now
be described with reerence 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 between
frame plate 54 and former plate 58. A 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 ge~rs 178
and 180 keyed thereto. A bracket 182, which is supported by
the frame, has a shaft 18~ mounted for rotation therein. A
gear 186 is mounted at one end of the shaft 1~4 and is meshed
with the gear 180 and a wo~m 190 is located at the other
end of the shaft 184 and is meshed with a worm gear 1~2 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 ~round the
iormer to the U-shaped configuration illustrated in Figure 8 of
the drawings, the cutter ~lade mechanism is operated to sever
the bag forming length from the continuous web and the sides of
the bag are then closed. As previously indicated, a tab 42
(Figure 1~ is formed between a pair of slits 40. In order to cut
the web to form the slits 4D, a knife mechanism is provided at
- each fiide of ~he former. The kn.ife mechanism will now be described
with reference to Flgures 9, 9a; 9b and 9c. It will be understood
that a knife mechanism is located at each side o the former,
although for simplicity of illustration only one knife mechanism
is shown in Figure 9 Each knie 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 lg8
carried by frame plate 56. A pair of knives 200 project outwardly t
10 from the support bloc:k l9A in a 5paced parallel relationship.
The support block 194 i5 releasa`bly secured with respect to the
face plate 198 by means of a pai-r of mounting screws 202. A
pair ~;f support a~ms 204 are mounted on the support b~E~c3cet 196
~nd project outwardly therefrom~ As shown in Figures 9 and lO of
;:c drawings, a spacer shaft 206 extends between the arms 204 and
a pair of link arms 208 are mounted at opposite ends of the shaft
206 to pivot about ~he axis of the shaft 206. A shaft 210 extends
between the link arms 208 intermediate the ends thereof and a
roller 212 extends between the inner ends of the link arms 208
and is rotatable about its longitudinal axis. Two pairs of shear
guide plates 213 are mounted on each shaft 210 to be movab~e
therewith toward and away from a knife 200 to move a portion of
a web locaked therebetween into enyagement with the knives 200
to cut the web to form the sli.ts 40.
Foldin Mechanism ,
Having formed the kabs 42, it is necessary to fold the
side panels inwardly about the former. The folding mechanism will
now be described with reference to Figures 8, ~ and lO of the
drawings.
: 30 As best shown in Figure 9 of ~he drawings, four shafts
l54, 155, 156 and 157 extend transversely between frame plates
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5~ and 56. Lever arrns 214 are secured to shfifts 155 and 157 for
movement ~ rewith and lever anns 216 are pivota~ly m~ ted on
sh~fts 154 and 156. The lever arms 214 and 216 are pivotably
connecte~ at their inner ends by a folding axm 218. It will be
noted that each folding arm 218 has an end portion 22~ projecting
from the a~n 216 toward the bottom support face of the former.
The outer extremity of t:he end portions220 are elongated vertical-
ly so that as they are drîven toward the plane of the bottom panel
they do not damage the web. The lever arms 214 and 216 are re-
- 10 tainea by the folding arm 218 so as to extend parallel to one
another so that by rocking the shafts 155 aI~d 157, the folding
a~ns 218 will remain parallel to one another while being moved l
- towards and away rom one another in an action plane spaced out- t
wardly Irom and parallel to the former plates 58 and 60.
Spring finger plates 219 are mounted on each oldin~ arm
218 and pro~ect inwardly therefrom toward the former plates 58
and 60. In use the plat2s 219 apply a pressure to the side ,-
forming panels of th web whic:h helps to maintain these panels
in the overlapping relationship when the discharge load is
applied to the bag to drive it ~rom the mandrel. The plates 219
retard the for~2ard 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 dri~Te mechanism shown in detail in Figure 8. The
drive mechanism includes lever arms 222 and 224 which are secured
to shafts 155 and 157 respectively. A connecting rod 226 has one
end secured to the outer end of the lever arm 222 ana a connecting
roa 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
-?0 -
:
3 i`
230 and the other erld Gf connector rod 228 is connected to rocker
arm 232. The rocker arm 230 is mounted for rotation on an exten-
sion of the shaft 16~ which projects outwardly fxom the frame
pl~te 54 ana the rocker arm 232 i5 mounted for rotation relative
to shaft 62. Cam followers ~34 ana 236 are located at ~he other
ends of rocker arms ~30 and ~32 respectively and engage cams 238
an~ 243 respectively which are mounted on ancl driven by cam shaft
136. Thus, it will be seen that ~ne full rotation of the cam
shaf~ ~36 will move the folding arms inwardly from the position .
10 ~hown to the position shown in Figure 9 and outwardly once again .
to the position shown in Figure B~ ¦
~rom the pro~ile of the cams 238 and 240 it wil:L be
apparent that in each complete cycle there are times when ~he
arms are in their outermost position and thei~ innermost position .
and there are also times when the arms are in an intermediate . 1 -.
position. It will also be understood that the position of the
. cams on the shaft 136 is such that the lower folding arm operates
to fold ~he lower side panel inwardly before the upper folding
arm operates to fold the upper side panel inwardly.
A mechanism is also provided for folding the portion of
: the web which projects outwardly from the bottom wall forming
~: portions into an outwardly overlying relationship with respect
to the side walls~ A major portion of this mechanism has previously ,
been described in describing the operation of the knife mechanism
used f~r forming the slits 40. As previously indicated, a roller
212 is mounted at the outer end of link arms 203 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 relationship with respect to the side wall o
-21-
the hag. The mechani5m for effecting movement of the roller 212
between the position shown in Figure 9 a~d Figure ~ O of $he draw-
ings includes a ~onnecting rod 242 which has one end connected to
the shaft 210 and its o~her end connected to a roc~er arm 244.
A cam followes 246 is located at the other end of the rocker arm
244 in engagement with-a cam 248. A connecting rod 243 is con-
nected to ~he shaft 210 associated wi~h the other roller 212
- - ana 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 2~. A return spring 250 extends between one arm of the rocker
- arm 244 and a support pin 252 which is secured to the frame. The
return spring 250 serves to urge the mechanism supporting rollers
212 to the outwardly spaced position illustrated in Figure 9 of
- the drawings.
- Discharge Mechanism
Having 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 showm in Figures 7 and 8 of the drawings, rectangular
shaped opening 254 is formed in the former plates 5g and 60 ad-
jacent the bottom wall forming edge thereof. With re~erence to
Figures 8 and 11 of the drawings, 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 ~ournalled
in a support bracket 260 which is mounted on the free end of a
support aYm 261 the other end of which is mounted on a bracket
263 which is secured to the a~jacent former plate (Figure 8).
The arms 261 are sufficiently flexible to enable the rollers 256
to be self-aligning with respect to the roller 212 and to accom-
.
-22
'
l~lJ~4-3 ~ :
moda~e l~mited movement of the rollers 25S away from and towards .
the rollerS 212. The rollers 256 are urged away from one another
~y a~ expansion me~hanism 265 which includes shafts 267 and 269 .
~hich are telescoped one within the other and com~ression spring
273 which reacts agains~ heads 271 at the free end of each shaft
267 and 269.
A drive pulley 262 is mounted to ~rivingly engage each
shaft 258. The pulleys 262 are each dri~en by a drive belt 264 .
which, as shown in Figure 10 of the drawings~ extend aro~nd pull-
eys 2G6 which are drivingly mounted on shafts 268. The shafts
268 are supported by the frame for r~tation about their axes~ the
supports for the shafts 268 being eliminated from Figure 10 of
the drawings so as to avoid over complication of the mechanism .
: il1uqirated. Gears 270 are mounted on each shaft 268 to mesh with .
t;je gears 178 and 180 which are rotatably driven ~y shaft 130 as .
previously described~ Thus, the discharge rollers 256 are driven
~y the motor 100 through the power train vreviously described. !~
wi~l, however be apparent that the discharge rollers 256 are
onl;i ~able of drivingly en~aging the bag when the folding rol-
lers 212 are located in the inner position illustrated in ~igure
11, !
As a bag is discharged from the former the crease lines r
: 39 are formed by the rollers 212 bearing against the edges of the
former. With reference to Figure 11 of the drawings, it will be
seen that each o~ the rollers 212 has an angularly inclined
shoulder 215 at each end thereof projecting radially outwardly to
~ a cylindrical sur~ace 213 of greater diameter than that of the
: main boay of the roller 212. A resilient collar 211 and a flex-
ible lip 217 are mounted in a recess formed in the roller 212 and
; 30 cooperate with the side edges 64 and 68 of the former to form a
sharp crease along edges 39 without damaging the ~ag as ~ is
~ischarged from the former.
~ !
~ - 23 -
~: I
.. ~,3L,~4ii3
~nwinding Mechan _m
To penmit a ch~ngeover from one ~oil of bag fonming
material to anvther~ two unwinding support shaf~s are provided.
As shown in Flgure 12 of the drawings, ~ne of the support shafts
is identified by ~he reference numeral 290 and the other is iden-
tified by the reference numeral 2Y2. These shafts may be sup-
ported by the frame or they may be mounted on sel-supporting
support stands~ At the input end to ~le former, a rol}er 77 is
mounted for rotation on the outer end of a pair of }ever arms
10 ~94 ~shown in broken lines). The other en~s of ~he lever arms
294 are pivotally mounted for rotation about the axis of a shaft
296~ A contrQl lever 298 projects outwardly from the shaft 296
ana is operable to mo~e 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 rolIer 78 to drive a web therebetween
or a position in which it will cooperate with the roller ?9 to
drive a web therebetween. In the embodiment shown in Figure 12,
a web 12 is being unwound from a first coil l0 around guide rol-
ler~ 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-
wou~d 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 arouna guide rol-
lers 299, 300a, 302a. ThusJ it is possible to replace a coil
without disrupting the operation of the hag forming machine.
Method of Operation
The bag ~orming machine described above can be set up
so as to proceea from the starting configuration illustrated in
~igure 12 of the drawings to the point where a bag is discharged
30 in an op~n configuration by following one or other of several
se~uences. The following description of the method of operation
443
refers to one such sequence in which after an initial set~up, the
bag forming machine comes to rest in a position ready to effect
an immediate di5charge of a bag in ~he open configuration from
the former ~nd to simultaneou51y commence the forming of a sub-
sequent bag to th0 configuration of the bag whichis in th~ proce~s
of being discharyes.
Thus, with reference to Figure 12 of the drawings, when
the two rolls of bag forming material have been mounted as pre-
vious-y described and the control lever 298 set to unwind the irst
web, the operator will activate the bag forming mechanism, gen-
erally by means of a foot pedal or ~he like, to cause the motor
100 to drive the power train. Initially, the discharge ~ollers
~56 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 discharge of a bag from the former, if a bag had been located
; on the former, the feed mechanism will be activated as will be
-cribea hereinafter to feed a web around the former.
The knife 84 is then activated to cut the bag forming
., ~
~Q l~nl~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-
ani~:~ remains in a "hold" position in which the web is folded to
tl , required bag configuration but the seal is not totally made
until the bag 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
-25-
g2tes 150 ~etween the Gpen and cl~sed pOSitions~ The track 304
illustrates the timlng and operation of the feed mechanism and :
the operation of the lower fold arm.
Track 306 illustrates the timing and operativn of the
upper fold arm.
As previously indicated, after the initial set-up, the .
machine is in the position in which a bag is substantially fully
formed on the former but is not totally sealed. This position
is represented by the zero degree (O~ marking on Figure 13.
10 The sequence ~f events in the operation o the machine can best
be ~scribed by pxoceeding to read the diagram illustrated in
~:~ Figure 13 in a counterclockwise direction. When 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 t
as C~own ~etween the 20 and 40c positions of Figure 13 the dis-
ch3..ge xoller 212 is moved to its innermost position in which
~~ i will press the bag into driving engagement with the discharge
ro-l'ers 256. Simultaneously, the gates 150 will move to the open
pos,:io.-.. ~s shown in track 304, the upper and lower folding
arms will remain in their lowermost position for a short period
of ti~e after the initial movement o~ the discharge rollers 212.
~: This period of time is sufficient to enable the discharge rollers
to move sufficiently close to the sides of the bag to prevent
the side forming panels moving away from the former. Thereafter,
the upper 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 lower folding anms are raised
-26-
"` ~
clear of ~he guide track o~ the former so as to be out of the
path of the feed of the next bag. At the 160 displacement posi-
tion, the fully formed bag has been discharged from the former
and the rollers 212 begin to move away from the rollers 256 and
continue to do so until about the 200~ mark. At the same time,
the gates 150 begin to move inwardly to move the guide bel~s 140
; and 142 to a position to guide the web around the former. ~t
about 180 displacement, the solenoid valve 120 is activated to
release the clutchl24 to permit the feed mechanism to operate to
drive the unwinding web around the former. The feed mechanism
is operational up to about the 25~ position whereupon the solenoid
valve 1~0 is again activated to operate the clu~h 12~ to interrupt
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 r the slits
be-ng completed at ~he 280 mark whereupon the mechanism is part-
ially retracted. As shown with reference to track 3~2, the main
cuttcr blade mechanism is activated between the 280 mark ~Id t'
the 3~ ~ark to cut the bag forming leng~h from the continuous
20 web. Simultaneously, between the 280 mark and the 320 mark,
; the lower fold anm is moved to its innermost position thereby
foldil3 the lower si~e wall forming portion inwardly about the
for~er. At about the 300 mark,the upper fold arm begins to move
inwardly and continues to do so to about the 350 mark to fold
the upper side wall foxming portion inwardly 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 activat-ing the switch
286 to disrupt the power supplied to motor 100 causing the mech-
anism to come to rest in the holding position.
-2~-
From the foregoing~ it will be apparent that the present
invention pro~ides a simple and efficient appara~us for forming
....
a bag. ~hile it is to be understood that various modifications
of the apparatus will be apparent to those skilled in the art,
~here are a number of features of the apparatus described in ~he
~referred embodiment which are particularly advantageous. F
: An example of a particularly advantageous feature of the
app~~atus of the present invention is the fact that the mechanism I -
is l~ ely mechanical so that it is capable oE being serviced by
~10 a mechanic having only a basic knowledge of mechanical mechanisms.
Furthermore, all of the mechanical controls are effected from a
single cam shaft.
In tests carried out with a test model of this apparatus,
~if~ic~?7~y was experienced in discharging the bags from the former.
The d-,-ficulty appeared to result from the fact that while the !`
di.so',-îge ro~lers were initially required to engage the sides of
the bag which are several layers thick, as shown in Figure 6, ~he
rollers subsequently move to engage the web of the thickness of
tJ~ overlap. Initially, the discharge rollers 256 were mounted
on ~ixed bearings located on the former plates. ~ith this con
struction, although a bag could be formed without difficulty,
the appearance of the bag was, on vccasion, adversely affected
by lelative movement occurring between the oppositely disposed
side panels at the overlap. It was found that by mounting the
rollers 256 so that they are able to float and are self-aligning,
this difficulty ~as been largely overcome.
A further difficulty which was experienced in preliminary
tests was in maintaining the overlapping relationship at the side
walls until the bag was fully dischargedO 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-
,
-28-
.
. . .
11'~(~4 ~3
charge rollers 212 and 256.` This diffîculty has been over~ome
by the simple expedient of pro~iding the spring biasing ~ingers
219 on each of the folding arms 218. The ingers 21g pre~s
against the side wall forming por~ions of the bag above the plane
of the o~erlap so that when a discharging load i~ applied în the
plane of the overlap, the movement o~ the bag in the area under-
lying t:he pressure fingers 219 in a direction towar~s the dis
~arge is retarded, thus tending to direct the overlappin~ edges
wardly 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
~he side wall forming panels may be folded inwardly. The guide
ro'lers 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
82 nreferably have a ridged underface which engages ridges formed
in the base of the various grooves in the ~arious ro~lers about
. which they extend so that the rollers are positively drIven.
;~: 20 ~t will be noted that whîle many of the elements of the
bag forminy machine are movable, the former is itself stationary.
One of the advantages to a stationary former i5 that the space
oc-upied by the machine need be only slightly greater than the l~
ov~rall 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~ therefor~, important to minimize
the size of the bag forming machine. In preliminary work, the
; applicant did develop machines in which the former was movable.
However, such machines were quite large by reason of the need to
provide space for accommodating movement of the former.
-29-
.
The use of flexible belts to form the outer guide members
considerably sin~lifiea the construction of the outer guide.
Considerable difficulty was experienced ln attempting to devise
~ mechanism which would 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 flexibl~ guide
belts 140 and 142 and extending these belts axound the corners
formed at the bvttom wall forming portion and mounting the outer
end thereof on the movable gates. By combining the 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
~o that the overlapping edges of the web along which a seal is
to be formed are dri~en between the discharge rollers so that
the overlapping edges are pressed together by the discharging
rollers 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
discharged from the former it will automatically assume and retain
thc open configuration and will have no memory tending to urge
t;.-c bag towards a lay-flat or knock-down configuration.
In the method of forming the square bottom bag by means
of the apparatus of the preferred embodiment, it will be noted
that while the web is subjected to bending about the rollers 72
and 74 to the U-shaped configuration, this bending does not form
any per~anent crease lines which wou}d 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 auced by the conventional bag forming methods in which the webis creased to enable it to be stored in a knock-down configuration.
~30-
il~04~3
Tests have indicated that a square bottom bag constructed by
the methoa described and the apparatus othe preferred embodiment
using a conventional paper ba~ roll stock of the type co~ nly
- used for packaging groceries will maintain it~ open configuration
when discharged 50 that it i5 open to facilitate loading Wit}
groceries or the lika.
Variou~ modifications of the present invention will
l~e apparent to those ski~lea in the art. One modification is .
illustrated in Figure~ 14 a~d 16 o~ the drawings. AS shown in
10 Figure 14 of the arawings, a }~and 22 of a thermosetting a~hesive
or a radiation ~nsative aahesive is applied to the outer face
16 of the web 12 at the marginal edge of the side closure :Eorming
portions 34. It should be noted that no adhesive band is applied
-
to the inner face 18 of the web 12. In order to form a seal,
the 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 wall o~ning portion. In this ,'
position, the band of adhesive 20a which is applied to the t~
20 marginal edge portion of the lower side wall forming wall member
is in intimate contact with the inner surface of the opposite
side wall forming portion 3~. Thereafter, the bottom corner
1ap 35 i5 folded inwardly to the position shown in Figure 16.
The critical areas of the heat sensitive adhesive are then
activated to bond the overlying portions of the side wall c~osure
members together in the config~ration shown in Figure 16. It
will be noted that the portion of the adhesi~e band 20 which is
located on ~he ex~ernal sur~ace of the side wall after folding
to the position shown in Figure 15 ser~es to secure the end 1,
flap 35 in the inwardly folded position. Thus, it will be seen
i
-- 31 --
;- '
t ~ ()4~3
that a bag may be constructed in which the adhe~ive is in the .
form of a ~:hermo~etting adhesive or an adhesive of a type which
is activated by rad~ation o~ one form or another, A bag may be
constructed in this configuration in the apparatus previously
described by the addition of a heat sealing element upstream
from the sealing and dispenser rollers. Alternatively, the
sealing rollers may be heated to an extent sufficient to cause
the bands o adhesive 28 to be activated during aischarge of
the bag from the former. ,
While it is possible to use adhesives which are acti- ;
vated by one focm of radiation or another such as thermal radia-
tion, there is a substantial advantage to ~he use of the pressure
sensiti~e adhesive of the type described in the embodiment illus-
trated in Figures 1 through ~ of the drawings. The pressure ',
sensitive adhesive does not require a radiation or heating
device to be present in the bag forming apparatus and, pro~ided
adequate pressure is applied, it is not necessary to provide
a minimum dwell time in oraer to achieve the required adhesion.
On the other hand, the use of the heat sensitive or radiation
sensiti~e adhesive may serve to eliminate the need to provide
the adhesive at both the inner and outer faces of the web so
that there may be a saving in the amount of adhesive usea.
The present invention provid~s a method and apparatus
for manufacturing a bag which is discharged in an open configu-
ration. The method and apparatus are so simple that the operation '
of making a bag may be carried out by the end user rather than
by a converter. Thus, the packer may simpl~ 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.
- 3~ -
In the foregoing disclosure 9 reference has been made
to the act that the cutter mechanism for severing the bag
forming length from the continuous web include~ a cultter bl~e
whic:h has a plurality o~ V-shaped teeth which are driven direct-
ly through the web. As previously ind~cated, t:his mechanism
has the advantage that it requires a minixnal amc)unt of spa ::e .
A further advantage of this mëchanism is that in cutting through
the web, the teeth form an irregular edge acxoss the web. This
is in contrast to ~he very sharp edge which is formed by a knife
10 such as a guillotine. This is extremely important in the manu-
fa~ture o~ bags which are to be manually loaded in which ~he
operator is required to pass his hand or arm through the open
end o~ the bag during the loading operation. A sharp edge on
a bag such as a grocery bag would represent a substantial hazard
to the packer~
In the preceding disclosure the advantages to be de-
rived from the fact that the bottom of the bag is not crea~ed
tu the extent required with conventional bags have been discussed
at te~7th. In the conventional knook-down paper bag it is nece-
20 ssary to form a 360 fold along the edges of the bottom wallpanel so that the bag c~an lay flat for storage purposes. This
360 ~old causes a considerable number of the fibres of the body
of a web o~ 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
constructed in accordance with an embodiment of the present
inven~ion to assist in the formation o a flat.bottom wall whi~h
w~i.ll provide a stable support for the empty bag. In the con-
siluction of a bag accuraing to the methods described hexein
30- before it is only necessary ts orm a 90 fold between the front,
- 33 - .
34~3
bolttom and back walls as the })a~ is discharged in the open
coniguration, thus the folding does not di~mage the fibrç!
strUcture of the web to the exterlt required to obtain a lay flat
conf igura~ion .
These and other advantages o the method and apparatus
of the presen~ invention will be apparent to those skilled in
the art.
- 34 -
