U.S. patent number 3,671,033 [Application Number 05/092,087] was granted by the patent office on 1972-06-20 for machine and method for folding plastic bags and the like.
This patent grant is currently assigned to Coast Machinery, Inc.. Invention is credited to John B. Coast.
United States Patent |
3,671,033 |
Coast |
June 20, 1972 |
MACHINE AND METHOD FOR FOLDING PLASTIC BAGS AND THE LIKE
Abstract
An automatic, variable speed, plastic-bag-folding machine which
takes flat plastic bags, rolls, folds, flattens and packages the
bags; the machine consists of a conveyor belt assembly (FIGS. 1
& 2) fed by the discharge of a plastic-bag-making machine which
feeds the bags into rolling, folding (FIGS. 6 & 7) and
multi-bag packaging sections (FIG. 8), synchronized by a pneumatic
control system (FIG. 9); the preferred embodiment produces the
tubular, rolled bag by a circularly disposed set of interdigitated
rollers (FIGS. 3-5); a second embodiment utilizes a continuous belt
having a geometric circular rolling section therein to produce the
tubular rolled bag (FIGS. 10 & 11). Having formed the rolled
bag, a vertical pin located at the middle of the tubular bag is
thrust perpendicular to and against the tubular roll pulling the
flexible bag from the rolling section and producing a half-fold; as
the bag is pulled from the rolling section it is passed between two
inwardly biased rollers to flatten the bag and then pushed into the
multi-bag packaging section consisting of a tightly fitted pin slot
on a set of conveyor chains which holds and secures the folded bag
as the pin is retracted in preparation for the next bag folding
cycle; when the appropriate number of bags have been folded and
secured, a commercial packaging box is fitted beneath the loaded
slots and a set of fingers are activated to push the bags out of
the slots into the box.
Inventors: |
Coast; John B. (Baton Rouge,
LA) |
Assignee: |
Coast Machinery, Inc. (Baton
Rouge, LA)
|
Family
ID: |
22231445 |
Appl.
No.: |
05/092,087 |
Filed: |
November 23, 1970 |
Current U.S.
Class: |
493/462; 53/120;
493/9; 242/535.1; 53/118; 242/DIG.3; 242/535.4; 242/541.2;
242/542.2 |
Current CPC
Class: |
B65B
63/04 (20130101); Y10S 242/03 (20130101) |
Current International
Class: |
B65B
63/04 (20060101); B65B 63/00 (20060101); B65h
045/12 () |
Field of
Search: |
;242/55,66,DIG.3
;72/146,148 ;53/118,120 ;270/83 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Mautz; George F.
Assistant Examiner: McCarthy; Edward J.
Claims
What is claimed as invention is:
1. A folding machine for folding flexible sheet material such as
plastic bags and the like comprising:
rolling means for rolling the material into a roll comprising a
rolling section disposed about at least 180 degrees of a circle,
said rolling section presenting on its inward side a moving surface
throughout a substantial portion of said 180 degrees of a circle,
said moving surface driving the material into a roll, said roller
section being divided into at least two laterally disposed
sub-sections having an open, unobstructed area therebetween;
introduction means for introducing the material into said rolling
means;
removal means for removing the rolled material from said rolling
means, said removal means including an extended member extended in
a direction at least generally perpendicular to the axis of the
curved surface defined by said rolling section, the rolled material
being removed from said rolling section by the extended member
moving through and across said open area, moving the rolled
material out of said rolling section; and
folding means for folding the rolled material as desired after it
is removed from said rolling section by said removal means.
2. The machine of claim 1 wherein each of said rolling sub-sections
has a substantial width as measured along their longitudinal axes,
the total width of each being greater than the radius of said
circle, the width of said open area being substantially less than
the width of said rolling sub-sections.
3. The machine of claim 2 wherein each of said rolling sub-sections
are of equal width, said open area being in the middle of said
rolling means and said extended member contacting the rolled
material in the vicinity of its mid-section as the rolled material
is moved out of said rolling section.
4. The machine of claim 2 wherein said rolling section is a series
of horizontally disposed, juxtaposed, parallel rollers whose axes
are disposed about said circle to form the curved portion of said
rolling section.
5. The machine of claim 4 wherein said rollers have alternating
depressions and raised portions which interdigitate with the
alternating depressions and raised portions of the adjacent
roller(s).
6. The machine of claim 2 wherein said rolling section is a
continuous, endless moving belt system which follows a curved
path.
7. The machine of claim 2 wherein the linear speed of said moving
surface is at least equal to the speed at which the material is
introduced into said rolling means by said introduction means.
8. The machine of claim 7 wherein said linear speed is
substantially greater than the speed of the material.
9. The machine of claim 2 wherein said rolling section forms a
laterally and horizontally disposed cul-de-sac, the material being
introduced into the cul-de-sac formed by said rolling section at
its lower lip.
10. The machine of claim 2 wherein said extended member is a
vertically disposed elongated finger-like pin which extends down
across the full inner diameter of said rolling section as it moves
across said open area.
11. The machine of claim 2 wherein said folding means comprises a
pair of parallel, juxtaposed rollers which bear toward each other
and are disposed adjacent to said open area, said extended member
upon passing through said open area pulling said rolled material
through and passed said juxtaposed rollers for folding thereof.
12. The machine of claim 2 wherein there is included preliminary
packaging means adjacent to said folding means for temporarily
holding a series of rolled and folded materials prior to the
packaging thereof.
13. The machine of claim 12 wherein said preliminary packaging
means comprises a series of adjacent, opposing pins mounted on and
extending out from the periphery of a set of chains carried by a
series of rotatable sprockets, said extended member carrying and
depositing the rolled and folded materials into and between said
adjacent, opposing pins after passing through said folding means
for temporary storage.
14. The machine of claim 13 wherein said set of chains passes
around and over one of said sprocket at the point where the rolled
and folded material is deposited between the pins, causing the pins
to be open wide at their entry portion for easy entry of the
materials therein.
15. A folding machine for folding flexible sheet material such as
plastic bags and the like comprising:
rolling means for rolling the material into a roll comprising a
rolling section formed by two sets of a series of horizontally
disposed, juxtaposed, parallel rollers whose axes are disposed
about at least 180 degrees of a circle to thereby present on their
inward side a moving surface throughout at least a substantial
portion of said 180 degrees of a circle, said moving surface
driving the material into a roll, each set of rollers having each
roller parallel and in line with a corresponding roller in the
other set, said sets being laterally disposed to each other but
separated apart and having an open, unobstructed area
therebetween;
introduction means for introducing the material into said rolling
section;
removal means for removing the rolled material from said rolling
section, said removal means including an extended member extended
in a direction at least generally perpendicular to the axis of the
curved surface defined by said rolling section, the rolled material
being removed from said rolling section by the extended member
moving through and across said open area, moving the rolled
material out of said rolling section; and
folding means for folding the rolled material as desired after it
is removed from said rolling section by said removal means.
16. The machine of claim 15 wherein the length of said rollers is
substantially greater than the radius of said circle and the width
of said open area being substantially less than the length of said
rollers.
17. The machine of claim 16 wherein each of said sets of rollers
are equal in length, said open area being in the middle of said
rolling means and said extended member contacting the rolled
material in the vicinity of its mid-section as the rolled material
is moved out of said roller section.
18. The method of folding flexible sheet material such as plastic
bags and the like comprising the steps of:
1. providing rolling means for rolling the material into a roll
comprising a rolling section disposed about at least 180 degrees of
a circle, said rolling section presenting on its inward side a
moving surface throughout at least a substantial portion of said
180 degrees of a circle, said roller section being divided into two
laterally disposed sub-sections having a substantial width and
having an open, unobstructed area therebetween;
2. introducing the flexible sheet material in a flat state into
said rolling means, and rolling said sheet material into a roll by
said moving surface driving the material into a roll;
3. providing removal means for removing the rolled material from
said rolling means, said removal means including an extended member
extended in a direction at least generally perpendicular to the
axis of the curved surface defined by said rolling section;
4. removing the rolled material from said rolling section by means
of removing said extended member through and across said open area
of said rolling section and thereby moving the rolled material out
of said rolling section; and
5. folding said rolled material in half as the rolled material is
being removed from said rolling section and flattening the folded,
rolled material after it has been removed from said rolling
section.
19. The method of claim 18 wherein said rolling section is formed
of two sets of a series of horizontally disposed, juxtaposed,
parallel rollers whose axes are disposed about said 180 degrees,
and wherein step (1) further includes driving said rollers at a
relatively high speed, producing a centrifugal action forcing the
material out against said moving surface, and thereby positively
driving the material into a roll.
20. The method of claim 19 wherein said sets of rollers are of
equal length, said open area being in the middle of said rolling
means, and wherein step (2) includes introducing the material into
said rolling means so that the mid-line of the material is
introduced at said open area, the extended member contacting the
rolled material in the vicinity of its mid-section as the roller
material is being moved out of said roller section.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a bag-folding and packaging
machine specifically and particularly designed to handle sheet or
flat plastic materials such as are used for plastic bags, although
other equivalent sheet materials may be processed. The function of
the machine is to receive the discharged bags from a bag-making
machine at any given rate and to automatically process, fold and
package the bags so that they are ready for commercial
distribution.
In the past few years great studies have been made in the
production of plastic materials and the acceptance of plastic
versions of products over older versions of products made from
other materials. A dramatic example of this has been the great
demand for and acceptance of plastic bags for garbage and food
wrapping over the standard paper bags.
The drastic physical differences between cellulostic product or
paper bags and plastic bags have opened up new marketing frontiers
for the plastic bag manufacturing industries,particularly in refuse
bag production.
While not directly influencing the overall volume of solid waste or
methods of solid waste disposal, the recent upsurge of plastic
refuse bags has, in comparison to metal cans, made possible
cleaner, odorless, noiseless removal of garbage. In addition,
certain economic advantages are offered by fewer manhours for
maintenance and collection, no scrubbing of cans and less costly
pick-up or collection trucks.
Other advantages include: air and water tight plastic bags
eliminate messy pick-ups; there is less attraction for
disease-carrying insects and rodents; less storage space is needed
than is required for garbage can storage; injuries are reduced with
lighter weight sacks; and no empty cans remain after curb pick-up.
Regardless of the method used for garbage collection in our
American life style, the plastic refuse bag should serve an
increasingly major role in the ecology of our environment, thereby
increasing the already present need for a plastic-bag-folding
machine.
These plastic bags are made of film forming polymers such as
polyethylene, polypropelene and polyvinylchloride. In comparison to
their paper or cellulosic counterparts, the plastic bags have
substantially no structural rigidity, are thinner and have much
lower surface friction characteristics. As a result of these
different physical characteristics, the prior art solutions to
handling and manipulating paper bags or for that matter fabric
materials as well, for example, in the folding and packaging
stages, have been found to be inapplicable to or unworkable with
plastic bags.
The plastic bag manufacturers of today for the most part have had
to end the automated process prior to the folding step simply
because the inherent physical difference in materials cause
impossible operating difficulties using the automatic prior art
paper bag or fabric folding machines. Although many possible
variations of the prior art paper bag and fabric folding machines
have been experimentally tested and tried, the results have been
unsatisfactory, due largely to the basic physical property
differences.
The current manufacturers of bags, in an attempt to satisfy market
demands, have had to revert to hand-folding and hand processing of
each bag as it is discharged from the bag-making machinery,
resulting in the lower production rates, less reliability and
greater expense inherent in any hand or manual operation. The
advantages of a completely automated process versus a
semi-automated process, that is one which is dependent upon the
human element for completion of one or more steps in the process,
is well known and established. Complete automation of a repetitve
process such as bag folding and packaging is of course highly
desirable.
The present invention will replace the human element in the bag
production line and lower the price per unit, so as to lower the
ultimate consumer price.
Other advantages of the specific embodiment of the present
invention, particularly in its rolling and folding sections, are
inter alia that the rolling of the bag is inherently self-starting,
there is good roll obtained by there being a moving surface winding
completely around the roll forming section in which assisted by
centrifugal action which produces a strong a frictional drive
action. Moreover, the machine design results in easy bag removal
since there is no cone or solid mandrel in the roll, as is often
found in prior art machines and removal is completely achieved
without stopping the surface wind rolls. To date, prototype speeds
of sixty (60) cycles per minute have been achieved, and much
greater speeds are possible.
Various other objects, distinctions and advantageous features of
the present invention will become apparent from the description of
the preferred embodiment below.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a right, side view of the complete machine of the present
invention, showing the conveyor belt assembly, rolling, folding and
multi-bag packaging sections, the latter being partially cut
away:
FIG. 2 is a top, plan view of the conveyor belt assembly, rolling,
folding, and multi-bag packaging sections;
FIG. 3 is a cross-sectional, end view from the rear of the machine
along sectional lines 3--3 of FIG. 2,illustrating the driving
mechanism for the conveyor belts and for the bag rolling rollers,
and showing the interdigitation of the rollers;
FIG. 4 is a cross-sectional, side view along section lines 4--4 of
FIG. 2 of the rolling mechanism, illustrating a bag entering the
rolling section;
FIG. 5 is a cross-sectional side view along section lines 5--5 of
FIG. 2 of the rolling section, including the folding mechanism, and
illustrating the bag completely rolled and awaiting the bisectional
fold;
FIG. 6 is a cross-sectional, end view depicting the folding
mechanism;
FIG. 7 is a top view of the folding unit illustrating the creasing
mechanism;
FIG. 8 is an end view from the rear of the machine of the multi-bag
packaging section;
FIG. 9 is a schematic illustrating using ASA standard symbols of
the pneumatic control system for the machine of the present
invention;
FIG. 10 is a cross-sectional, side view, illustrating a second
embodiment of the rolling section wherein a continuous conveyor
belt system is used, and illustrating a bag in the rolling section;
and
FIG. 11 is a cross-sectional, front view along section lines 11--11
of FIG. 10, illustrating the belt of the second embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment of the present invention is a machine for
taking plastic bags and the like, ultimately folding them flat, and
packaging a certain number of the folded bags into boxes in a
positive, continuous and automatic manner.
As illustrated particularly in FIGS. 1 and 2, a discharged bag from
a bag-making machine is fed into an upper 1 and lower 2 set of
continuous or endless conveyor belts running in contact with each
other at the same surface speed, each set consisting of eight
two-inch-wide belts. The bag is held firmly between these belts and
conveyed to the folding section of the machine.
As is shown in the drawings, note for example FIGS. 2-5, the closed
width of the rolling section is quite substantial, that is, the
length of rollers 15 is substantially greater than the radius of
the circle about which the axes of the rollers 15 are disposed.
The belts 1,2 are supported by idler rolls 3 conveniently placed
along the belt path as desired. Belt tension is maintained on the
belts 1,2 by spring loaded tensioners 4, each belt having
independent tensioners.
As indicated in FIGS. 4 and 5, the upper belts 1 are friction
driven by a rubber covered upper drive roll 5, while the lower are
similarly driven by a lower drive roll 6. Both upper drive roll 5
and lower drive roll 6 are driven by a conventional chain drive
consisting of sprockets 7,8,9 and chain 10. Sprocket 7 is in turn
driven by a DC motor 11 which provides, for example, a 0-400 feet
per minute variable belt speed which can be easily set to match the
bag-making machine output rate as presently found in the
industry.
This chain drive also provides power for the right folder roll
section sprocket 12. Similarly the left folder roll section is
driven by means of the roll 5 and sprockets 13, 14. As seen in
FIGS. 2 and 3, sprocket 13 is fixed to the upper belt drive roll 5
and sprocket 14 drives the left roll section, sprocket 12 being its
analogous counterpart on the right roll section.
As best seen in FIGS. 4 and 5, the belt sections 1,2 feed the flat,
unfolded bag into a group of intermeshing or interdigitating,
driven rollers 15 whose surface interaction with the bag cause it
by a positive driving action to be wound into a roll. The axes of
the rollers 15 are disposed about 270 degrees of a circle, leaving
an opening into the bag rolling section into which the belt
sections 1,2 feed the bag. The peripheries of the rollers 15 facing
inwardly into the circle thus define a generally circular moving
surface which drives the bag around into a roll. Driving force is
transmitted to the bag by friction between the rubber surface of
the rollers 15 and the bag itself. Also the belts 1,2 push the bag
into the rollers 15.
Although the axes of the rollers 15 are shown disposed in a precise
circle, merely a curved disposition is satisfactory.
The rollers 15 thus form in effect a laterally and horizontally
disposed cul-de-sac having an inner moving surface for driving the
bag into a roll. Although, it is possible to introduce the bag into
the rolling section at another angle or direction than that shown,
it is particularly advantageous to introduce it at the bottom lip
of the cul-de-sac so that as the bag is driven upward it has a
tendency to roll back upon itself.
Centrifugal force, bag material stiffness and the increase in the
bag diameter as it is being rolled contribute to the normal force
which holds the bag against the drive rollers 15 surface and
positively guide it to its rolled condition. The surface speed of
rollers 15 is usually designed to be 20-30 percent greater than
belts 1,2. Provided sufficient friction is maintained between the
bag and drive rollers 15, the bag will completely roll up. The bag
is thus changed from a large, flat sheet to a rolled cylinder, the
first step in the folding process, without the necessity of a solid
inner mandrel. Although the solid inner mandrel found in prior art
systems is avoided in the present invention, enhanced interaction
between the bag and the moving surfaces of the rollers 15 may be
obtained if desired by adding a perforated tube in the interior of
the circle of the rolling section to provide outwardly directed air
jets, further pushing the bag outwardly against the rollers 15.
To prevent the bag from escaping between the rollers 15, the
rollers 15 have alternating protruding sections 16 which
interdigitate or intermesh with the adjacent rollers, as best shown
in FIG. 3. This is achieved by placing alternating rubber sleeves
16 on the roll shafts as shown. The degree of interdigitation or
intermeshing can be controlled by varying the sleeve width,
diameter, spacing and thereby the amount of overlap or intermesh.
Friction characteristics of the system can of course be varied by
changing the sleeve material and hence its properties.
Although in the disclosed embodiment all the rollers 15 are driven
at the same speed, their speed could be different. Particularly
each roller 15 could be run at a higher speed than its immediate
neighbor so that the last roller to touch the bag will be running
at a higher speed than the initial roller 15.
The structural supporting plates at each end of the rolling section
15 are sectioned along a horizontal line and hinged on pins. Easy
entry is thereby allowed into the cul-de-sac defined by the rolling
section 15, in case of bag jamming or any other occasion that
requires access to the interior of the machine.
The inside diameter of the rolling secton 15 is directly
proportional to the width of the folded bag. Therefore any change
in the diameter will effect proportionally the width of the folded
bag.
To guide the bag from the conveyor sections 1,2 into the rolling
section, a number of guides 17 are placed between roll 18 and the
initial or bottom drive roll 15; note particularly FIGS. 3-5. These
guides 17 also serve as guides for the lower belts 2. Similar to
the lower guides 17, there is an upper set of guides 19 which guide
the bag from the upper belts 1 into the roll section. They also
serve as upper belt guides.
In order to permit the removal and flat folding of the rolled bag
in a manner explained below, the rollers 15 do not extend the full
width of the machine but rather are divided into two separate but
interconnected side sub-sections. The central region 150 between
the central supports 150' of the side sections of the rollers 15 is
basically open and unobstructed. As is shown in the drawings, note
for example FIG. 2, the width of the open area 150 is substantially
less than the width of the roller sub-sections, that is, less than
the length of the rollers 15. As explained above, the two sections
of the rollers 15 are commonly driven and so interconnected by
means of drive shaft 5.
In order to protect the machine in case of bag jam-up or the like,
both sections of the drive rollers 15 are driven through an
overload slip clutch and sun gear drive system. As illustrated in
FIGS. 2 and 3, sprockets 12,14 drive via clutch disc 20 the main
sun gear 21. Clutch clamping pressure on the clutch disc 20 is
obtained by adjusting nut 22, thereby loading spring washer 23.
Tightening nut 22 increases the clutch clamping pressure. Sprocket
12, clutch disc 20 and gear 21 are loaded and supported between two
thrust bearings 24. The sun gear 21 drives gears 25 which are fixed
to roller shafts 15' thus providing power to the rollers 15. A jam
or overload will cause slippage between gear 21, clutch disc 20 and
sprocket 12, 14.
Although 270 degrees of curved rolling section 15 has been
illustrated it is possible to get a rolling section with much less
coverage, it being only necessary to supply sufficient coverage so
that the bag would have a tendency to fall back upon itself and
form a roll as it proceeds into the rolling section.
As a normal rule it would usually require 180 degrees of coverage
to properly form a roll.
The preferred embodiment described above requires a conveyor belt
assembly and, although completely integrated, a separate mechanism
for rolling the bag. In FIGS. 10 and 11, a second embodiment
accomplishing the conveying and rolling step using only one
continuous mechanism, namely a continuous belt mechanism, is
illustrated.
The continuous belt mechanism of FIG. 10 employs a lower 56 and
upper 61 belt conveyor assembly similar to the preferred
embodiment. However the lower belt 56, rather than immediately
returning as in the preferred embodiment, is guided into a
geometric circular section therein creating a rolling section
63.
A guide element 59 is positioned between the lower special belt 56
and the upper belt 61 at the entrance to the rolling section 63 to
facilitate the formation of the roll and avoid the possibility of
the bag following the belt out of the circular rolling section
63.
The lower belt 56 like the belts 1,2 of the preferred embodiment
can consist of eight belts, each 2 inches wide and on 3 inch
centers. A 4 inch opening between the two inside belts to allow the
passage of the integral pin folding mechanism 26-30 as described
supra should of course also be provided Although having open areas
between the belt, the total closed width of each belted rolling
sub-section would still be substantial, being still substantially
greater than the radius of the circular rolling section.
In order to provide positive control and positioning of the lower
belts 56, particularly in the rolling section 63, lateral pins 64
on the belts 56 ride in guides 59; note especially FIG. 11. The
belts 56 are driven by drive roller 60 and ride on and are
supported by idler rollers 55, 58, 62.
Noting particularly FIGS. 2 and 5-7, the fully rolled bag is
removed from the roller secton, folded in half and flattened in the
following manner. Pin 26, which is fully retracted while the bag is
being rolled, is driven down from packing gland 27 by air cylinder
28, as shown in FIG. 5. When pin 26 is fully extended, slider block
29 starts moving toward the rear of the machine away from belts 1,2
with the pin 26, gland 27 and air cylinder 28 mounted on and
carried by the slide block 29. Slider 29 is driven by air cylinder
30 and slides on guide bars 29. At the same time pin 26 is coming
down, flattening rolls 31 move in and flatten the bag along its
centerline position, as shown in FIGS. 6 and 7. Rolls 31 are in the
phantom line position (FIG. 7) during the rolling operation, and
move to the solid line position while pin 26 comes down and moves
past them. The movement of rolls 31 is provided by air cylinder 32
and appropriate linkages 33,34.
As slider block 29 moves to the rear of the machine to the right in
FIGS. 2 and 5, the bag is pulled between the inwardly pressing
vertical rolls 31 by the pin 26, thereby flattening and
transversely folding the bag in half. The bag is pulled through the
rolls 31 until the tail end clears the rolls 31.
After being rolled and folded flat, the bags are assembled and
packaged in the following manner, having particular reference to
FIG. 8. As pin 26 pulls the bag from rolls 31, the bag is pulled
between two sets of holding pins 35 which are mounted on chains
36,37;note FIGS. 1 and 2. When the bag is fully extracted from the
roll section and inserted and held between the pins 35, the pin 26
retracts and slider block 29 returns to its original position. As
each bag is pulled from the rolling and folding sections, chain 36
indexes and an open set of pins 35 is brought into position to
receive a new bag. Any appropriate indexer mechanism can be used.
The folded and held bags are moved by the pins 35 and chain 36,37
from the load position described above in a counter clockwise
direction (looking at FIG. 8) to a boxing section. A protective
shield 45 is supplied to prevent the bags from falling out of the
loaded slots from the loading position to the boxing section of the
packaging unit. When a desired number of bags are directly over box
38, pusher plate 39 driven by air cylinder 40, extends and pushes
bags off of pins 35 into the box 38. Alternatively, instead of
going into a box, the bags could be discharged into a holding
mechanism or tray, as desired. From the tray the bags could be
pushed into an end load box.
As illustrated, chains 36,37 are supported by sprockets 41, 42
& 43. Element 44 is a detent to hold the chains 36, 37 in
position while it is being indexed.
In order to control, coordinate and synchronize the various
elements and sections of the machine, an appropriate control system
with sensors is used. The sensing element for the control of the
various air cyclinders described above could be achieved by using
means such as air cams, solenoids or rotary actuators, to mention
but a few. A pneumatic or air system was chosen for the preferred
embodiment. An air proximity sensor 46,shown in FIG. 4, senses a
passing bag. The resulting signal controls a simple, conventional
sequencing pneumatic system which in turn controls all of the air
cylinders described above. Such a pneumatic system is schematically
illustrated in FIG. 9, standard ASA symbols being used.
The pneumatic control system operates as follows. Pressure of a
passing bag is detected by fluidic proximity sensor 46. Sensor 46
outputs an air pressure increasing the pressure in line A, causing
diaphram amplifier 47 to operate. Operation of amplifier 47
pressurizes line B which then causes air control valve 48 to shift.
Shifting of valve 48 retracts air cylinder 28 and extends air
cylinder 32.
When pressure in line C reaches approximately 15Psig, sequence
valve 49 shifts. Cylinders 28,32 are sized so that they will
operate at less than 15 Psig or at the sequence pressure. Shifting
of valve 49 causes air cylinder 30 to retract and air cylinder 51
to extend. Extension of cylinder 51 indexes sprocket 53 which
indexes chains 35,36. Any appropriate index mechanism may be used.
Cam 52 is fixed to sprocket 53. The air control valve 50, when
pressure is on line D, extends air cylinder 40.
When the end of the bag passes sensor 46, pressure in line A drops,
amplifier 47 returns to its original condition and line B is vented
to atmosphere through the amplifier. Valve 48 is returned by an
appropriate spring bias. Shifting of valve 48 causes the air
cylinder 28 to extend, air cylinder 32 to retract, and valve 40 to
shift when sequence pressure is reached in line F. Shifting of
valve 49 causes cylinder 30 to extend to its normal position and
cylinder 50 to retract to its normal position. Line D is thus
vented to atmosphere through valve 49. The control system will then
remain in this posture until sensor 46 senses the pressure of
another bag.
In most if not all of the prior art machines using a rolling
technique prior to the folding,a certain degree of rigidity of the
material being folded was necessary. By using a relatively high
speed conveying drive, the relatively rigid type of material such
as paper could be driven into a system of static circular guides to
thereby form a roll. However, plastic bag or sheet material, having
practically no rigidity, does not consistently work with such prior
art machines.
The present invention provides, not a static guide, but rather a
guide that generates or has its own driving force. The two
particular embodiments disclosed of the present invention for the
rolling section, namely, a set of driver rollers circularly
disposed and a continuous driven belt having a circular section,
provide a positive, dynamic carrying and driving of the bag into a
tubular roll. This positive, dynamic carrying and driving of the
bag into a tubular roll at high speed is an important element for
successful operation when dealing with low rigidity materials such
as plastic bag type sheet plastic.
Other embodiments of bag rolling sections are possible, the two
disclosed being of course merely exemplary.
Because many varying and different embodiments may be made within
the scope of the inventive concept herein taught, and because many
modifications may be made in the embodiments herein detailed in
accordance with the description requirements of the law, it is to
be understood that the details herein are to be interpreted as
illustrative and not in a limiting sense.
* * * * *