Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to a method of manufacturing bags, and to the
bags manufactured by the method.
Bags of thc general type disclosed herein are taught, for example, in
United States Patent No. 2,628,013, granted on February 10, 1953 to C. W. Vogt.
Other relevant prior art includes British Patent No. 1,131,063, published on
October 23, 1968 in the name of Windmoller and Holscher and United States PatentNo. 3,548,723, granted on December 22, 1370 to Sengewald.
In the Vogt United States patent, there is taught the manufacture of
paired bags that hang from a central support in such a manner that they may be
easily filled, and then separated and closed. Specifically, referring to column
1 of United States Patent No. 2,628,013, it is disclosed that an important
feature of the Vogt invention is that two bags are connected at their open ends
; and in such a way that they may be hung on opposite sides of a support with the
connecting portion resting on the support.
Also known in the art are so-called "deli-bags" which, in the manner
taught in British Patent No. 1,131,063, hang from a support in such a manner
that individual bags can be easily filled with foodstuffs and the like and then
removed from the stand and closed. Such bags are normally open-mouth bags, and
have to be closed by means of a twist-tie or similiar closure dcvice. Such bags
have been used extensively in food packaging operations, such as in take-out
restuarants where they are particularly convenient for wrapping sandwiches.
Further known in the art are small plastic bags having a closure top
comprising a pocket adjacent the mouth of the bag and facing in a direction
opposite to the mouth of the bag. To close such bags, it is necessary only to
fold the pocket over the mouth of the bag.
~hile deli-bags have been known for many years, and bags with the
locking top as described above have also been known for many years, to my
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knowledge no one has devised a product capable of use in a foodstore for packag-
ing foodstuffs, that can easily be torn from a support, and cheaply and quickly
manufactured while providing the locking top feature and thus eliminating the
need for a separate tie. The present i-nvention aims to provide such a bag,
using a minimum of materials and using conventional manufacturing techniques.
The invention accordingly provides a method of manufacturing bags
comprising the steps of;
~ i) forming a web of thin~ flexible thermoplastic material substan-
tially in the form of a tube, having a central portion and two ends doubled back
over the central portion at a pair of first fold lines;
~ii) folding terminal portions of said ends back ober said ends towards
the first fold lines at a pair of second fold lines;
(iii) forming a tear line adjacent each second fold line;
~iv) heat sealing and severing the web transversely to define first
pockets between the central portion and ~he ends, and second pockets between the
ends and the terminal portions to define oppositely facing pairs of bags;
~v) stacking the pairs of bags thus defined; and
~vi) heat sealing the stacks of bags together centrally of the central
portion.
The invention also provides a bag construction comprising
a plurality of webs of thermoplastic film having two ends,
each of said two ends being doubled back at a fold line over a central
: portion of each web to form two first pockets having oppositely facing and spaced
` apart mouths,
terminal portions of said two ends being folded outwardly towards said
fold lines to form second pockets facing outwardly and oppositely away from each
other,
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said two first pockets defining with the second pockets a pair of
separate bags, spaced from each other by a portion of the central portion of
the web,
spaced transverse lines of weakness formed in said portion of the cen-
tral portion of the web, and
means for mounting a plurality of webs with the said portion of the
central portion of each web on a suitable stand whereby, when mounted on said
stand, the individual bags may be removed from the bag construction by tearing
along the line of weakness and the second pockets folded over the mouths of the
first pockets to enclose articles within the bags.
Specific embodiments of the invention are shown in the accompanying
drawings, in which:
Figure 1 is an illustration of the step of manufacturing an extruded
plastic tube for use in manufacturing bags according to the invention;
Figure 2 illustrates the simultaneous production of tubes of the type
shown in Figure 1, but of differing dimensions;
Figure 3 illustrates, serially, the steps of manufacture of bags
according to the invention;
~ Figure 4 illustrates in a manner similiar to Figure 3 how bags of
- 20 differing dimensions can be manufactured from a single tube;
Figure 5 illustrates the manner in which a stack of bags may be
formed with posting apparatus;
Figure 5a is a section on the lines Sa-5a of Figure 5;
Figure 6 illustrates a stack of bags, as formed in the step of Figure
5, on a suitable stand;
Figure 7 illustrates a completed bag before closure;
Figure 7a is a section on the line 7b-7b of Figure 7;
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Figure 8 is an illustration of a closed bag, and;
Figure 8a is a section on the line 8c-8c of Figure 8 showing a bag in
its closed condition.
A prefe~red method of manufacture of bags according to the invention
is from extruded plastic tube. ~owever, it is possible, by suitable folding, to
form the bags from a weh. For convenience of description, the bags are described
as manufactured from extruded thermoplastic tuhing, which may be either plain or
embossed.
Normally, such tubing is formed from polymeric materials, including,
polyethylene and like n)aterials. Such materials are easily handled in bag making
machinery in that they are easily folded and heat sealed.
In Figure 1, an extruder 11 is used to extrude a continuous tube 10.
In Figure 2, there are illustrated four different sizes of extruders lla, llb,
llc and lld which produce bags of differing widths 10a, 10b, 10c and 10d. It
will be evident that one can manufacture several different sizes of bag simul-
taneously, thus speeding production.
Illustrated in Figure 3 are the sequential steps in a desirable me~hod
of manufacture. One side of the tube is first slit by a suitable knie 13, which
in known manner is supported from above and i5 provided with a plate 14 to ensure
that only one side of the bag is slit. Downstream of the knife 13 is a spreader-
folder 15, also of known type, for folding the web to both sides of the slit at
16 and 16a. Downstream again from the spreader-folder 15 is a serrating tool
17, which forms a score or tear line on both sides of the central portion of
~- the web at 27 and 28, adjacent the fold formed by portions 16 and 16a. A
punch or punches 18 may be provided to perforate the central portion of the
web at suitable intervals, for purposes to be described below. Finally, knife
and sealer 19 is provided; this is of known type and is heated to a temperature
~; suitable for both heat sealing and cutting the web, transversely, to separate
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discrete portions 20.
Referring specifically to the individual, cut-off portions 20, it will
be noted that they comprise two separate bags 21 and 22, heat sealed along their
edges 23 and 24, to form two open mouthed bags with outwardly facing pockets 25
and 26 respectively. A central perforated web portion may be separated from the
bags by tearing along the lines 27 and 28 in a manner to be described below.
The steps illustrated in Figure 4 are identical to those illustrated
in Figure 3, with the exception that for special situations where two sizes of
bag are required, the cutting, spreading and folding, serrating, and punching
operations are of~-set from the center of the tubular web. For small articles,
one bag of the pair can be used, and for larger articles the other bag of the
pair can be used.
After the bags are produced by the steps shown in Figure 3, they are
stacked, in an orderly fashion, to form a block 29 ~Figure 5). After a suitable,
predetermined number of bags have been formed into the block, they may be posted
by a heat tool 30 which forms holes in the central portion. These holes, as
illustrated in Figure 6, are dimensioned and located so that they can be used
in cooperation with a stand 32 having a transverse bar 33 and vertically ex-
tending posts 34 that mate with the holes 31. The stand may be dimensioned so
; 20 that it is free-standing, to rest on the floor or on a table at a work station,
or in the manner illustrated in British Patent No. 1,131,063 attached to a wall.
` The tool 30,~in posting~ would heat seal the block of bags 29 together to form
an easily handled unit.
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~ As also illustrated in Figure 6, an individual bag may first have
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` articles placed in it through the open mouth. The bag may then be torn off
~; ~ from the block along the respective score line; Figure 6 illustrates a partial
:~ tear 35 of a fillecl bag. After the bag is removed from the block 29 of Figure
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6, the pocket may be folded over the open mouth of the bag to form a closed bag
as shown in Figures 8 and 8a.
It will be appreciated from the above that several advantages flow
from the present invention. First, compared with known techniques for the manu-
facture of these bags, there is less waste material in that the plastic material
that would normally be of double thickness in the center of the block and there-
fore wasted is folded back, and used to Eorm the pocket for the locking top of
the bag. The thickness of the central portion of the block of bags is substan-
tially reduced by virtue of the presence of only a single layer of plastic
material, as compared with the prior art of conventional type where a double
layer of plastic material would remain in the middle. The advantages of the
locking top type bag for use in a variety of environments will be self evident.
The person packaging foodstuffs or the like does not have to maintain a separate
supply of closures or clips for closing filled bags, and relies instead on the
locking top feature. Once the apparatus for carrying out the method described
in this application is set up, the additional cost of manufacture is no more
expensive than the manufacture of the less advantageous bags of the prior art.
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