Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Transport Container
The invention pertains to transport containers for free-flowing materials,
particularly for
bitumen in a heated or cold state, wherein the container body of the transport
container
essentially has the shape of a truncated pyramid with a bottom, sidewalls and,
if
applicable, a top surface with fill opening that consist of flexible material,
and wherein
the sidewalls are reinforced with stabilizing means in the lower region near
the bottom
so as to prevent deformation.
Transport containers of flexible material are frequently also sold under the
name Big
Bags or Flexible bulk containers and primarily serve for transporting pourable
or free-
flowing goods.
The present invention is based on a prior art disclosed, for example, in AT
505 805 Al.
This application concerns the stabilization of the shape of such a flexible
transport
container after it has been filled with bitumen, wherein this objective was
attained by
providing the fabric panels that form the sidewalls with stabilizing means in
their lower
region, and wherein said stabilizing means are inserted or sewn into the
fabric panels.
In the figures, the concrete disclosure shows the arrangement of intersecting
pleats that
are sewn into the material of the sidewalls, wherein the seams end within the
fabric
panels.
In practical applications, it was already known to provide stabilizing seams
in the
sidewalls prior to the priority date of the aforementioned application, for
example in the
form of vertical seams that extended from the bottom edge of the transport bag
up to
approximately half its height.
Although such seams and sewn pleats in the sidewalls stabilize the shape of
the
transport bag to a certain degree, they proved to have certain disadvantages
in practical
applications. On the one hand, the additional seam in the bag wall represents
an
additional step during the sewing operation that increases the costs. The
reinforcing
effect depends on the quality of the sewing work and on the quality of the
fabric material
such that it is not always easy to exactly predict the stabilizing effect of
mass-produced
items.
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Another disadvantage of seams can be seen in that they tend to burst open such
that
either the seam is opened and the stabilizing effect is rendered ineffective
or, in the
worst-case scenario, the transport bag tears open. Seams also are always
associated
with weakening of the sewn fabric. It is furthermore disadvantageous that such
sewn
pleats end within the fabric material such that the occasionally substantial
tensile forces
are introduced into the fabric in any case and overstretch and damage this
fabric in
certain areas. The strength and dimensional stability achieved with such seams
and
other bands that are inserted or sewn into the fabric panels ultimately
depends on the
strength of the fabric material only.
The production of transport containers with a container body that has the
shape of a
truncated pyramid and with an arrangement of sewn, reinforcing fabric pleats
is also
known, for example, from DE 84 21154.7 U1. Another transport bag for bitumen
with
the shape of a truncated pyramid is disclosed in the prior art according to AT
009 644
U1. This transport bag also features an arrangement of an inner lining in the
form of a
plastic film.
The packaging of bitumen into transport containers of flexible material is
associated with
certain problems. Bitumen is only liquid to semi-liquid at higher temperatures
and
solidifies into a cool melt at lower temperatures. However, such melts have
the
characteristic of also not being completely solid at lower temperatures, e.g.
at room
temperature. Bitumen behaves like a slowly flowing mass in the cooled state.
This is
also one of the reasons why bitumen was until now predominantly filled into
dimensionally stable receptacles such as, e.g., conventional bitumen barrels.
However,
these have the disadvantage of also having a large volume in the unfilled
state, wherein
a relatively high transport loss also occurs due to the fact that a large
percentage
adheres to the inner wall of the barrels when they are emptied.
The main problem of flexible packaging containers can be seen in that the
filled bags
lose their shape during transport, particularly if bags are stacked on top of
one another
in containers such that the bags bulge laterally. This can also lead to such
bulging
transport containers no longer fitting into the containers used for overseas
transport.
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The problem of dimensional stability may become even more severe if low
temperatures
cause the typically used material such as polypropylene or polyethylene to
lose its
strength.
The present invention is based on the objective of developing packaging
containers of
the initially cited type that are self-stabilizing while they are filled with
liquid bitumen or
similar free-flowing materials and also remain free-standing without losing
the desired
shape after the product has been deposited and, in particular, the bitumen has
solidified. The container should also maintain its strength at low ambient
temperatures.
The objective of the invention especially can be seen in eliminating the
initially
described disadvantages and in realizing the means for stabilizing the shape
of the
container body in such a way that the occurring tensile forces are adequately
absorbed
on all sides and the transport container is also prevented from bursting open
in the
harsh practical applications of the transport industry. In addition,
stabilizing means of
this type must be very inexpensive because the costs of non-returnable
containers like
the transport containers in question are eminently important in the transport
industry.
Another objective consists of relieving the fabric of the sidewalls from the
tensile forces,
wherein it should also be possible to achieve a prestress of the stabilizing
means.
The above-defined objective is attained with the present invention, in
particular, in that
the stabilizing means are realized in the form of stabilizing belts that
respectively
connect the bottom corner regions to the adjacent lateral edges in an
intersecting and
tension-proof fashion, wherein the fastening points of the stabilizing belts
on the lateral
edges lie within the lower two-thirds of the overall height of the container
body near the
bottom.
Other advantageous characteristics of the invention are disclosed in the
claims and the
following description, as well as the drawings.
The invention is elucidated in an exemplary fashion below with reference to
the
drawings.
Figure 1 shows an oblique view of the inventive transport container.
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Figure 2 shows the transport container with removed outer wall and without
inner lining.
Figure 3 shows an element of the inner lining prior to the insertion into the
transport
container.
Figure 4 shows a horizontal section through the transport container.
Figure 1 shows an exemplary embodiment of a finished transport container prior
to the
filling process. The container body 1 comprises a bottom 2 - that is concealed
in Figure
1 - four sidewalls 3 and an upper termination in the form of the top surface 4
with a fill
opening 5. All of these two-dimensional structures largely consists of one or
more webs
of a fabric material that is sufficiently strong for absorbing the high
forces, but still allows
the smallest pack size possible. Bags of this type can carry loads in excess
of 1.000 kg.
The lateral edges 9 are sewn together with lateral edge seams 14. The bottom
edges
19 are also formed by a seam that serves for sewing the respective sidewalls
to the
corresponding edges of the bottom. The top surface edge 20, on which the top
surface
4 is connected to the upper edge of the sidewalls 3, extends on the upper end
of the
container body 1. In the exemplary embodiment shown, the top surface edge 20
is
reinforced with a sewn-in belt 21. Edge belts 15 are sewn in along the lateral
edges 9,
wherein two adjacent edge belts 15 respectively form a lifting strap 16 on the
upper end.
The container body has the shape of a truncated pyramid such that the surface
area of
the bottom 2 is larger than the surface area of the top surface 4.
According to the invention, the container body is stabilized with stabilizing
means in the
lower region near the bottom. These stabilizing means 6 are realized in the
form of
stabilizing belts 7 that respectively extend from the bottom corner regions 8
to fastening
points 10 along the lateral edges 9 in a free-hanging fashion, i.e. without
intermediate
fastening on or to the corresponding sidewall. This ensures that the
significant forces
acting from inside during the filling of the transport container are
transmitted to the
reinforced regions of the container body by the stabilizing means in the form
of the
fastening belts without damaging the fabric. The fastening points 10 are
preferably sewn
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on in the lower two-thirds of the height of the container body such that
bulging of the
transport container is largely prevented.
The stabilizing belts 7 are preferably sewn into the bag with a prestress,
i.e., the belts
are slightly shorter than the free length between a bottom corner region 8 and
the
corresponding fastening point 10. When the transport container is filled,
however, the
generally rigid stabilizing belts are slightly stretched such that the
container body can
assume the illustrated shape of a truncated pyramid. This shape is optimally
maintained
due to the tensile stress of the stabilizing belts.
Figure 1 also shows the filler neck 22 on the upper edge of the container
body, wherein
this filler neck protrudes upward through the top surface 4 and serves for
filling the
container with the respective product. The filler neck can be closed with a
hasp 25.
The transport container furthermore features conventional information means,
e.g. a slip
23 with identification means such as barcodes, and a document pocket 24.
In a preferred embodiment, the container body respectively comprises two
layers,
namely an inner fabric 12 and an outer fabric 11, at least on the sidewalls
and on the
bottom. In the drawing in Figure 2, the outer fabric of the sidewalls is
removed such that
the inner fabric 12 of the sidewalls is visible. This figure also shows the
stabilizing belts
7 that respectively connect a bottom corner region 8 to a fastening point 10
of the
adjacent lateral edge and thusly absorb the tensile forces of the respective
product. At
the intersecting points 13, the retention forces of both intersecting belts
cooperate such
that the highest retention force occurs at this location. The intersecting
points 13
preferably lie in the region, in which the most intense bulging of the
transport container
would occur.
Although the illustrated two-layer structure is preferred, the scope of the
present
invention also includes embodiments with only a single-layer structure, in
which the
sidewalls and/or the bottom therefore consist of only one fabric layer. The
intersecting
stabilizing belts 7 may in this case be arranged either on the outside of the
body or
inside.
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Figure 3 shows a film blank for realizing the preferably provided inner lining
17, wherein
this inner lining is produced when for such blanks are placed into the bag as
an inner
layer. The inner lining is closed on the bottom and fastened with the aid of
fastening
straps 18 that are sewn into the lateral edges 9. In other respects, the inner
lining 17 is
freely suspended in the container. In Figure 1, the upwardly extending filler
neck 22
protrudes from the top surface 4.
Figure 4 shows a schematic horizontal section through a transport container
according
to Figure 1.
In this exemplary embodiment, each of the four sidewalls 3 comprises two
fabric layers,
namely the outer fabric 11 and the inner fabric 12. Intersecting stabilizing
belts 7 are
arranged between these fabric layers and intersect in the intersecting points
13.
The lateral edge seams 14 are situated on the lateral edges 9 such that all
fabric layers
11, 12 and the ends of the stabilizing belts 7, as well as the fastening
straps 18 of the
inner lining 17, are solidly connected to one another, wherein the edge belts
15 are
additionally sewn in. The belts and fabric layers may be sewn together in the
lateral
seam by means of an overlock seam 26 and a safety seam 27 as illustrated in
Figure 4.
In the bottom corner regions, it is preferred to utilize a chain-stitch seam,
wherein the
bottom edge seam along the bottom edges 19 may also be realized in the form of
a
chain-stitch seam.
It goes without saying that the inner lining should consist of a very thin
film, the
softening point of which lies slightly higher than the filling temperature of
the bitumen.
On the other hand, it should be possible to liquefy or soften the inner
lining, which is
usually removed from the bag together with the cold bitumen during unloading,
when
the bitumen is reheated such that the inner lining can either be easily
removed or
incorporated into the bitumen. A temperature of 108 C may be an advantageous
filling
temperature for the bitumen. The softening point of the film therefore needs
to lie above
these 108 C, for example between 110 and 120 C.
The fabrics of the outer transport container preferably consist of
polyethylene or
polypropylene and their softening point is significantly higher, e.g., between
190 and
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220 C. The fabrics are preferably coated with PE or PP such that the fabric is
strengthened.
The drawings do not show the arrangement of the warp and the weft of the
fabric webs.
They usually lie such that the warp extends vertically from the bottom edge to
the top
edge and the weft extends normal thereto and parallel to the bottom edge.
Since it is a
well-known fact that any fabric has its greatest elasticity in the direction
extending
diagonally to the warp and the weft, the tensile forces are absorbed by the
intersecting
stabilizing belts that also extend diagonally and introduced into the lateral
edge seams
and the bottom corner regions. The fabrics may consist of plain woven fabrics
or circular
woven fabrics.
The stabilizing belts should be as strong as possible, but still be sewable.
It is preferred
to utilize multifilament belts, in which the multifilaments extend in the
longitudinal
direction of the belts.
Typical weights per unit area for the wall material are 70 to 150 g/m2 for the
inner fabric
and up to 250 g/m2 for the stressed portions of the outer fabric. For example,
the outer
fabric on the bottom may have a higher grammage than that of the sidewalls.
The
bottom, the sidewalls and the top surfaces may be formed of separate blanks
that are
connected to one another on the edges. The portion of the container body
formed by
the outer fabric may also be connected to the inner fabric on the top surface
edges only.
The preceding description of the stabilizing belts extending between the
fastening points
in a free-hanging fashion referred to the sidewalls means that they are not
held at any
point of the inner or outer sidewall fabric such that they transmit a tensile
load. In the
stressed state, the tensile forces are only introduced into the lateral edge
seams and
the bottom corner regions of the container body.
The lower fastening point of the stabilizing belts lies in the bottom corner
regions 8. This
fastening point does not have to be exactly the corner, at which the bottom
edge 19 and
the respective lateral edge meet. The bottom corner region also extends into
the close
vicinity of the edges. For example, the lower fastening point is located in
the lateral
edge 9 approximately 3 to 10 cm, preferably about 5 cm, above the bottom
corner. It is
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important that the high tensile forces of the stabilizing belts are introduced
into the
strong edge seams.
With respect to the advantageously utilized belts, i.e. the stabilizing belts
and also the
edge belts with the lifting straps, it should furthermore be noted that the
strength of the
transport container can be significantly improved and adapted to the ambient
conditions
by selecting the material accordingly. Depending on the climatic conditions,
very low
temperatures below -30 C, at which other popular materials such as
polypropylene
become brittle, may also occur such that the transport bag would no longer
have a
sufficient load carrying capacity.
In this case, the inventive solution may consist of utilizing belts with
larger dimensions
for the transport container or of providing belts made of materials that are
more resistant
to cold temperatures such as, e.g., metallic woven fabrics, steel wires,
polyamide fibres,
natural fibres, etc.
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List of Reference Symbols:
1. Container body
2. Bottom
3. Sidewall
4. Top surface
5. Fill opening
6. Stabilizing means
7. Stabilizing belt
8. Bottom corner region
9. Lateral edge
10. Fastening point
11. Outer fabric
12. Inner fabric
13. Intersecting points
14. Lateral edge seam
15. Edge belt
16. Lifting strap
17. Inner lining
18. Fastening straps
19. Bottom edge
20. Top surface edge
21. Belts
22. Filler neck
23. Barcode
24. Document pocket
25. Hasp
26. Overlock seam
27. Safety seam
