Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates -to an lmprovement in
sacks for storage and transport of bulk goods, for example,
road salt and artificial fertilizer for forestry and agricul-
tural usage. Due to the constantly increasing costs in labour,
attempts have been made in all fields to avoid manual handling
of goods to the greatest possible extent and, in regard to
artificial fertilizer, for example, attempts are made at avoid-
ing units of 25 and 50 kg which are handled manually when a ;
fertiliæer spreader, which may take a ton, is -to be filled,
and~any experiments have been made in the attempt to provide ~
sacks which can be filled with several hun~red kg and even ~ -
tons of material to be transported or stored, and which can -
be handled more rationally than smaller units. However, the ~ -
embodiments known ~itherto have created more problems than
they have solved. Even with requirements of both five-fold
and seven-fold safety measures, it has proved that uneven
distribution of the strains when the sack is hoisted can
lead to rupturing of the sack and discharge of the contents
at an undesired location, with subsequent trouble and con
sumption of time and labour for collection, if collection is
at all possible.
The previously known embodiments of sacks which
take up to 1000 kilos and which are usually called "large-si~e
sacks", -therefore, have been based on various ideas. One
type of sack has two parallel runners at two opposing edges of
the opening ~or suspension on a fork-like support. Another
known type is provided with lifting straps which are welded
to the exterior of the sack, however, in addition to the
expense of this embodiment, there is little to ensure that
the straps will remain so precisely in place that the lifting
forces are uniformly distributed and not concentrated in
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smaller areas where they can lead to strains which exceed the
tearing strength of the material. Large sacks have also been
effected in conventional manner and in the form of a conventional
sack which is lashed and manually lashed around a rod or other
lifting member. Since it is manual work, the lashing varies
from sack to sack with consequent variations in the dist~ibution
of strains. There are, of course, no problems attached to the
production of sacks which, with a great degree of safety, can
contain several tons if necessary; however, one requirement
is also that the sack must be inexpensive enough to be disposed
- of after a single use. Several of the above said -types of sacks
are so expensive that they are used repeatedly, and the problem
and cost of returning the sacks then arise and it is possible
that they must be reconditioned before they can be refilled.
During the development of the sack according to the
present invention, scale up to bags of the type described in
United States patent No. 3,358,904 was also considered. However,
.t was soon reali~ed that neither the design nor the material
or production methods of such bags could be adapted -to the sack
in question. Mere scale up of such bags would give sacks that
not only would lack the necessary strength, but would also be
unsuitable in other respects.
The present inven~ion provides a large size sack for
the transport, lifting and storage of large quantities of free-
flowing bulk materials, said large size sack comprising: a ~ ;
single piece of woven material formed of woven lengthwise strips
and transverse strips; said single piece of woven material being
folded in half alony a fold line extending transverse to said ~-
lengthwise strips, thus fonning a sack top at said fold line and
two overlapped sack panels having adjacent sack bottom edges
extending paxallel to said fold line and parallel adjacent sackside
edges e~tending transverse to said fold line between opposite
ends of said bottom edges and said fold line; said adjacent sack
bottom edges being closed to form a closed sack bottom; said
adjacent sack side edges being sewn together from said sack
bottom to positions spaced from said fold line to form two sack
side seams, said side seams being spaced from said fold line to
define therebetween two side openings; said sack panels having
therein, at a location between said side edges thereof, a single
longitudinal slit extending perpendicularly from said fold line
and parallel to said side edges, said slit forming a sack filling
opening; portions of said sack panels between said slit and
said two side openings forming two lifting loops for lifting the
sack, said lifting loops comprising unbroken integral elongations
of said woven material of said sack panels; substantially all of
said lé~gthwise strips of said woven material being continuous
and unbroken by said slit, such that upon lifting the sack by ~.
said lifting loops, the critical stress along said lengthwise
strips from said fold line to said sack bottom is evenly dis-
tributed among all of said lengthwise strips; and said woven
material having a sufficient size and strength such that -the
sack can be filled with.a quantity of free-flowing bulk material
of a weight of from several hundred kilograms to several tons
without rupture of said material when the thus filled sack is
lifted by said lifting loops.
The material in the folded edge on either side of the
filling opening is thus an uninterrupted piece of material with-
out score lines, and the sack can be carried by this material
in that the side edges are provided with openings at the ends
adjacent the folded edge. When such a sack is lashed, the
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material on either side of the filling opening forms two ad-
jacent loops b~ which the sack can be lifted and, inasmuch as
the loops are integral with and identical to the material in the
sack otherwise, a natural and uniEorm distribution of the stretch
strains in the material of the sack is ensured, whereby an
economical utilization of the sack is obtained even with great
demands to safety. The sack is further very simple to produce
from for example, a textile of polypropylene laid double and
sewn along the side edges on already existing machines, the
filling opening being formed by a single slit inwardly from the
folded and unsewn edge. The sack is then provided with a closed
bottom, for example also by sewing. sy terminating the seams at
a distance from the folded edge, the openings necessary for forma- -
tion of the said loops when the sack is lashed are provided. ;
In use of the sack, a lashin~ element is preferably ~`
tied around the woven material adjacent and below the end of the
slit remote from said fold line to close the sack and permit
the sack to be lifted by the two lifting loops.
By way of example, a specific embodiment in accordance
with the invention will now be described, with reference to the
accompanying drawings in which: ~ ~
Figures 1 - 7 illustrate the steps of forming a sack ~ -
from a flat piece of suitable material to a filled and lashed
sack ready for storage and transport.
Figure 1 illustrates a material piece of, for example,
polypropylene textile 1 and this piece is folded at its centre
line 2. It then has the shape illustrated in Figure 2 with a
folded edge 3 at the top and free edges 4 and 5. The free edges ~ -
4 and 5 are, in the example, illustrated, sewn together by seams
6 so that the sack is formed. The seams 4 on both sides
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terminate at the arrow 7 so that, above the said seam, openings
8 are produced. As filling opening, the sack in Eigure 3 is
provided with a slit 9 through both layers of the material and
directed lengthwise of the sack from khe folded edge 3. When
the sack is filled, it is disposed on a base layer and suspended,
as illustrated in Figure 4, so that the slit opens and the sack
can be filled therethrough as indicated by the arrow 10. During
the filling operation, the sack may be suspended in any expedient
manner and, subsequent to fillin~, it stands by itself on the
lO base layer and the upper part is drawn together as illustrated
in Figure 5. The sack is now to be lashed in that around the
upper end, a rope ll is knotted so far down that the slit 9 is
closed and so that, above the rope ll (Figures 6 and 7) two r
adjacent loops 12 are formed from the parts of the material of
the sack located on either side of the slit 9, and including the
openings 8
The sack can now be hoisted by means of the loops 13
for transport and, as explained, the distribution of force is
uniform since the material in the sack and in the loops is the
20 same, and there will be no variation from sack to sack. The
sack is further so inexpensive that it can be disposed of after
a single use.
The sack may comprise one or more layers and have an
inner sack which is closed per se when necessary. The outer sack
which actually carries the weight, is made from a textile of
fibrous material e.g. woven polypropylene or the like. The inner
sack can be made from a cheap and not necessarily strong material
as polyethylene, paper or the like. Furthermore, in place of the
simple embodiment illustrated in the drawings, the sack may be
30 provided with insertions in the sides thereof when desired.
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As an alternative or complementary device to the
application of the above mentioned inner sack, the sack may be
provided with an inner lid made of plastic sheeting or woven
material. The lid is fastened to the inside of the sack and
may have the form of a hose with the same diameter as the sack.
The lid may also comprise a circular or cone formed sheet ex-
tending in a neck of suitable diameter. The lid is closed by
lashing. When filling the sack, the lid's neck is connected to
the filling tube and the sack can be blown up with air before
filling~
Other embodiments of the invention will be readily
apparent to a person skilled in the art, the scope of the
invention being defined in the appended claims. -~
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