[0001] The present invention relates to a bag folding apparatus, and particularly to an
apparatus for use in connection with the folding and packaging of bags made from a
flimsy material, such as a plastics material.
[0002] The use of bags made of plastics material has found wide acceptance and a large commercial
market has been developed. The physical differences between flimsy bags such as bags
made from plastics and bags made from paper or cellulosic products has required the
development of new machinery and equipment in order to produce plastics bags economically.
[0003] Generally, plastics bags can be made of film forcing polymers such as polyethylene,
polypropylene, and polyvinylchloride and the like and can be multilayered. In comparison
to the paper or cellulosic counterparts the plastics bags have substantially poor
structural rigidity, are thinner, and have much lower surface friction characteristics.
[0004] Generally, the manufacturing of plastics bags starts with a plastics film which is
formed into separate bags and these bags are then folded and packed into boxes which
will eventually be puchased by the consumers.
[0005] In a typical production system, the plastics bag is formed and then discharged into
a receiving region from which the final folding operation proceeds. Each bag is discharged
into the receiving region in a substantially flat state and slides into the region
until a barrier generally referred to as a fence prevents further sliding of the bag.
When the bag comes to rest, it must be in substantial alignment with the fence.
[0006] It has been found that poor alignment of the plastics bag in the receiving region
can interfere with subsequent operations and thereby reduce production efficiency.
Poor alignment tends to occur frequently for the plastic bags in known apparatus because
the leading edge of the bag which is to be stopped by the fence has poor structural
rigidity so that this leading edge can sometimes be distorted. Another cause of poor
alignment is that the bags are delivered to the receiving system such that the leading
edge is not square with the feed direction. In order to attempt to obviate such problems,
it is known to provide a plurality of corrugations in each bag prior to the bag entering
the receiving system, such corrugations extending in the direction of feeding of the
bags to the receiving system. These corrugations are intended to stiffen the leading
edge of the bag thereby allowing it to square up when it strikes the fence.
[0007] This problem of poor alignment is particularly prevalent when the bags have a relatively
large dimension in the feed direction. It has been found that a large plastic bag
which has been folded one time before being discharged even with corrugated regions,
can become misaligned because of the poor retention of the corrugated regions during
the movement of the bag into the receiving region.
[0008] It is an objective of the present invention to overcome this problem and thereby
improve the production efficiency and economy for bags or sheets made of flimsy material
such as plastics.
[0009] It is to be understood that the invention is not intended, however, to be limited
to bags and that the invention can also be used in connection with sheets of flimsy
material and the like.
[0010] In accordance with the present invention, there is provided an apparatus for use
in connection with the folding of bags or sheets made from a flimsy material, comprising
feeding means operable for discharging bags or sheets successively in a feed direction
with each bag or sheet having a plurality of corrugated regions having grooves in
said feed direction and having undulations in the transverse direction, receiving
means operable to receive the bags from the feeding means and to maintain in each
bag or sheet fed thereto at least some of the corrugated regions at least until each
of the bags stops its movement along the feed direction, and a fence in or adjacent
the receiving means for stopping the movement of each of the bags or sheets along
said feed direction.
[0011] Preferably, the feeding means comprising a pair of shafts and a plurality of spaced
tyres mounted on the shafts and positioned to cooperate with each other to provide
the plurality of corrugated regions in each bag fed therethrough and to move that
bag in the feed direction.
[0012] The receiving means preferably includes a plurality of upper rods and a plurality
of lower rods which cooperate with each other to maintain in each of the bags at least
some of the corrugated regions at least until each of the bags stops its movement
along said feed direction.
[0013] The invention is described further hereinafter, by way of example, with reference
to the accompanying drawings, in which:-
Fig. 1 diagrammatically shows the overall arrangement of a bag making machine together
with a folding and packaging apparatus;'
Fig. 2 is a plan view of an apparatus in accordance with the present invention with
portions removed;
Fig. 3 is a partial side elevational view of the apparatus of Fig. 2 with portions
removed;
Fig. 4 is a cross-sectional view of the apparatus along the section line 4-4 of Fig.
2;
Fig. 5 is a cross-sectional view of the apparatus along the section line 5-5 of Fig.
2 with portions removed and illustrates a plastics bag being corrugated;
Fig. 6 is the same cross-sectional view as Fig. 4 with additional portions removed
and illustrates a plastics bag in the initial stages of being transferred for subsequent
folding and packaging; and
Fig. 7 is the same as Fig. 6 but shows the plastics bag in a subsequent position of
being transferred.
[0014] Fig. 1 shows a complete system for producing folded and packaged bags from a roll
of plastic film. For the embodiment shown, plastics film 10 in the form of a roll
11 is moved around a roller 12 into a bag making machine 13. The plastics film 10
on the roll is prefolded longitudinally.
[0015] It is to be understood that the plastics film 10 could be supplied from an extruder
and thereafter prefolded prior to entering the bag making machine 13. The plastics
film 10 can also be supplied from other known means such as from a roll without the
film having a fold and prefolding the film prior to its entering the bag making machine
13.
[0016] Typically, the bag making machine 13 can be a Model 208 Polyethylene Bag Making Machine
manufactured by G. T. Schjeldahl Company in combination with a Model Accu-Folder Folding
Machine manufactured by FMC Corporation.
[0017] The machine 13 produces a bag 14. The bag 14 is longitudinally folded with the crease
being the leading edge. The crease, however, is usually not well defined due to the
characteristics of the plastics film. The bag 14 moves through a feeding means such
as a corrugating roller 15 into a receiving means 16. The bag 14 comes to rest in
the receiving means 16 in a generally flat condition and thereafter is removed from
below, such as shown by bag 17, by nip rollers 18 in combination with belts 19 for
additional processing and packaging by apparatus 20.
[0018] From Figs. 2 and 3, it can be seen that bags can be moved by a conveying system 22
to corrugating rollers 15 into a plurality of upper rods 23 and a plurality of lower
rods 24. An adjusting system 21 allows the groups of rods to be moved vertically to
obtain a predetermined spacing at a predetermined height. Each rod position within
its group is adjustable. Each of the corrugating rollers 15 comprises a drive shaft
25 and tyres 26.
[0019] Generally each of the tyres 26 is an annular ring of an elastic material and each
tyre 26 frictionally engages the respective shaft 25. The material can be a plastics
material such as polyurethane or a rubber-like material or the like. The tyres 26
are grouped in clusters and serve to grip and remove bags from the conveying system
22 when the corrugating rollers 15 are driven. Each group of tyres 26 forms a corrugated
region in a bag passing between the corrugating rollers 15.
[0020] As used herein, the term "corrugated region" refers to a physical variation in the
film as shown in Fig. 5 which shows four such "corrugated regions".
[0021] The corrugated regions provide good structural rigidity to the bag so that when the
leading edge contacts the barrier, the bag resists deformations which would tend to
misalign the bag. The corrugated regions improve the rigidity of the leading edge
as well as the rigidity of the overall body of the bag so that the bag misalignment
is corrected when it strikes the barrier.
[0022] From Figs. 2 and 3, it is evident that the invention is not directed to a system
requiring bags to be stacked in the receiving region.
[0023] The interaction between a bag 27 and the tyres 26 can be seen by reference to Figs.
4 and 5. The relationship between the rods 23 and 24 with respect to the tyres 26
can be seen by reference to Fig. 4.
[0024] Generally, the end portions of the upper rods 23 near the corrugating rollers 15
are positioned to extend to approximately the lower extremities of the tyres 26 on
the upper rod 25. Similarly, the end portions of the lower rods 24 near the corrugating
rollers 15 are positioned to be near the upper extremities of the tyres 26 on the
lower rod 25..
[0025] Fig. 6 shows a plastics bag after it has come to rest after sliding between the rods
23 and 24 to a barrier such as fence 28. The fence 28 is a linear arrangement of fixed
vertical cylinders as shown in Figs. 2 and 3.
[0026] The bag 27 is moved towards pinch rollers 18 by an air knife device 30. Generally,
an air knife comprises a linear arrangement of air nozzles which provide a blast of
air for, in this instance moving a plastics bag-towards the pinch rollers 18. A typical
air knife is described in U.S. Patent No. 3,918,698.
[0027] For a bag removal system using an overheated air knife and pinch rollers, it is preferable
to define a corrugation in the bag to correspond to the space between the pinch rollers
and generally to extend towards the pinch rollers. As shown in Fig. 6, it is preferable
to have a rod 31 above the bag 27 and tending to deform the bag 27 towards the rollers
18.
[0028] Fig. 7 shows the plastics bag 27 after it has been engaged by the nip rollers 18
and-is being pulled downward between belts 19.
1. An apparatus for use in connection with the folding of bags or sheets made from
a flimsy material, comprising a feeding means (15) operable to discharge bags or sheets
(14) successively in a feed direction with each bag or sheet (14) having a plurality
of corrugated regions having grooves in said feed direction and having undulations
in the transverse direction, a receiving device (16) operable to receive said bags
or sheets from the feeding means (15), and a fence (28) in or adjacent the receiving
device (16) for stopping the movement of each of the bags or sheets (14) along said
feed direction, characterised in that the receiving device (16) includes means (23,24)
operable to maintain in each bag or sheet (14) fed thereto at least some of said corrugated
regions, at least until the movement of that bag or sheet in the feed direction is
stopped by the fence (28).
2. An apparatus as claimed in claim 1, wherein said feeding means (15) comprises a
pair of corrugating rollers.
3. An apparatus as claimed in claim 2, wherein each of said corrugating rollers comprises
a drive shaft (25) and a plurality of tyres (26) axially mounted on each of said shafts,
said tyres being positioned on said shafts to cooperate to interact with each bag
or sheet fed therethrough to form said ccrrugated regions.
4. An apparatus as claimed in claim 1, 2 or 3 wherein the receiving device (16) comprises
a plurality of upper rods (23) and a plurality of lower rods (24), said rods (23,24)
being positioned generally along said feed direction and with respect to at least
some of said corrugated regions to maintain said corrugated regions at least during
the movement of said bags or sheets in said feed direction.
5. An apparatus as claimed in claim 4, wherein said receiving device further comprises
an adjusting means operable for changing the relative vertical positions of said plurality
of upper rods and said plurality of lower rods.
6. An apparatus as claimed in claim 4 or 5, wherein said fence is positioned to provide
a barrier to the movement of said bags or sheets fed to said receiving device whereby
said bags or sheets come to rest in a predetermined position.
7. An apparatus as claimed in claim 5 or 6, wherein each said bag or sheet fed to
the receiving device comes to rest above a set of nip rollers (18) and below an air
knife (30) operable to force a stream of air against a generally imaginary straight
line along said bag or sheet to move said bag or sheet towards the nip rollers (18).