The invention relates to a device for sealing sacks made of fabric, to which
tubular sack bodies can be supplied, comprising an adhesive application device
for the continuous application of adhesive in an adhesive region and a
transportation device for transporting the tubular sack bodies transversely to their
longitudinal axis through the adhesive region, such that adhesive 5 can be applied to
a strip region of the tubular sack bodies.
The invention further relates to a method for sealing sacks made of fabric, in
which the tubular sack bodies are transported transversely to their longitudinal
10 axis by means of a transportation device, wherein the tubular sack bodies are
spaced apart from one another in the transport direction and the sealing comprises
a continuous application of an adhesive in an adhesive region, such that adhesive
is applied to a strip region of the tubular sack bodies.
15 The tubular body of a sack is usually formed from a tubular round material or a
flat material connected to a tube on the longitudinal edge. Next, the tubular body
is sealed at at least one end, in order to form a sack.
Sealing the tubular bodies usually takes place in a transverse transport step, i.e.
20 the individual tubular bodies are transported in a flat state transversely to their
longitudinal axis, wherein there is a gap or space stretching in the transport
direction between the individual tubular sack bodies. The tubular sack bodies are
sealed, for example, by sewing them up or adhesion. Adhesion can take place
3
either by continuous application of adhesive or application in intervals. With the
application in intervals, the adhesive is only applied to the tubular sack bodies and
not in the spaces between consecutive tubular sack bodies. With continuous
application on the other hand, the adhesive application is not interrupted. When
the individual sack bodies pass through the point of adhesive application 5 one after
another and spaced apart from one another, this leads to the adhesive being
applied in the spaces between consecutive sack bodies as well.
The continuous application of adhesive has numerous advantages compared to
10 interval application. For example, controlling the adhesive application nozzle is
substantially easier and thus both construction costs and maintenance costs are
lower than with interval application. A disadvantage of continuous application is
the problem described above, in that the adhesive is also applied between
consecutive sack bodies, such that adhesive is lost and the equipment becomes
15 dirty.
Usually a plate is arranged below an adhesive application device and the tubular
sack bodies are led between the adhesive application device and the plate. In
doing so, the plate serves as a support for the edge region of the sack bodies, the
20 region to be sealed, wherein the plate also serves as the counterpart for at least one
pressure roller, with which the edge region is pressed to the sack body after it is
folded, in order to stick the folded edge region by using the adhesive. In a
continuous adhesive application, however, adhesive ends up in the spaces between
4
consecutive sack bodies on the plate, and this adhesive has to be regularly
removed, which requires interrupting the operation and is thus undesirable.
The woven fabric of the sacks processed within the scope of the invention
preferably consists of monoaxially stretched polymer tapes, 5 in particular
polyolefin or polypropylene tapes. These tapes are produced by stretching
polymer films, in particular polyolefin or polypropylene films, usually by four to
ten times, whereby the molecule chains are aligned in the longitudinal direction of
the tapes and in this direction have approx. six to ten times the strength compared
10 to the original film. The width of the tapes is usually approx. 1.5 to 10 mm, the
thickness 20 to 80 μm.
It is one object of the current invention to provide a device of the kind named
above, with which the problems connected to the continuous application of
15 adhesive can be solved.
To achieve this object, the invention, with a device of the kind named above,
provides that an adhesive removal device that is separate from the transportation
device is arranged below the adhesive region in order to remove the adhesive
20 applied by the adhesive application device in the space between the individual
tubular sack bodies. The adhesive application device is led in such a way that the
continuously applied adhesive ends up in the region of the spaces between the
consecutive sack bodies on the adhesive application device, whereby the
5
superfluous adhesive is transported away from the adhesive region and cleared to
a different place, away from the adhesive application device and can be further
processed. The adhesive application device is thus not a part of the sack body
transportation device, but rather constitutes an independent unit which can
preferably be separately 5 switched on or off.
Preferably, the adhesive removal device is formed by a powered belt or a powered
roller. The running direction of the belt can essentially be chosen freely, meaning
for example parallel or normal to the transport direction of the tubular sack
10 bodies. It is preferred that the running direction of the belt is chosen substantially
parallel to the transport direction of the tubular bodies.
A preferable development provides that the adhesive application device is an
extruder. An extruder offers the opportunity to provide an adhesive application
15 device by simple means, said device enabling a consistent adhesive application. It
is also possible to form this extruder in such a way that it is able to be heated in
order to enable hot melt adhesive to be used for sealing the tubular sack bodies.
Preferably, the adhesive removal device, in particular the belt or roller, is arranged
20 below an adhesive outlet opening of the adhesive application device. In doing so,
the adhesive exit spot and a region of the belt are always on a vertical axis. This
enables the vertical application of adhesive from an adhesive exit spot by using
gravity.
6
It is furthermore preferred that the adhesive removal device, in particular the belt
or the roller, is heat resistant. This allows the safe application of hot adhesives as
well, without the adhesive removal device being damaged by the heat.
5
In order to avoid sticking the adhesive to the belt, it is provided in a preferred
development that the side of the adhesive removal device facing the adhesive
application has an anti-adhesive coating. Thus, the removal of the adhesive by the
adhesive removal device, in particular by the belt or the roller, and thus cleaning
10 is made easier. Particularly preferable is that the belt is provided with an antiadhesive
coating on both sides in order to make it more difficult for other
substances or unintentionally applied adhesive, for example, to be stuck to the
underneath of the belt as well.
15 In order to keep the belt clean, it is preferred that a cleaning device is provided,
for example a brush, that is able to be fitted to the adhesive removal device and
works together with it. Thus the adhesive removal device, in particular the belt or
the roller, can inexpensively be continuously cleaned. It can also be provided that
the cleaning device is fitted to the adhesive removal device at intervals in order to
20 clean it.
The drive for the adhesive removal device can be formed separately to the drive
for the sack body transportation device. In a preferable embodiment it is provided,
7
however, that the adhesive removal device is powered by means of the drive of
the sack body transportation device. The drive of the sack body transportation
device, for example an electric drive, is in this case coupled with the adhesive
removal device, wherein the adhesive removal device can be designed to be able
to 5 be coupled and uncoupled.
A particularly simple embodiment provides that the belt is formed as a revolving
belt. Thus a closed belt is arranged in such a way that it is led around diversion
rollers.
10
Preferably, the belt is arranged below a transport level of the tubular sack bodies
and above a stationary plate. In this way the superfluous adhesive can be
completely removed from the belt. If adhesive unintentionally runs down onto the
side of the belt, then this adhesive is caught by the plate and the adhesive does not
15 come into contact with the ground or other regions.
Furthermore, it is preferably provided that a folding device for folding an end
section of the fabric is arranged after the adhesive application device in the
transport direction. Two layers of the tubular body and the adhesive placed
20 between them are pressed against one another by one such folding device,
whereby the tubular body is sealed. Both a one-sided folding device, in which
only one end of the tubular body is sealed, and a two-sided folding device, in
which both ends of the tubular body are sealed, can be provided.
8
In one preferred embodiment it is provided that the adhesive application device is
arranged to be stationary. Thus the adhesive region is always in the same place.
Alternatively, it can also be provided that the adhesive application device is
arranged moveably to allow a more flexible application 5 of the adhesive.
It can further be provided that the adhesive removal device is arranged adjustably,
in particular transversely to the transport direction of the sack bodies. This can be
necessary for a moveable adhesive application device, for example, or generally,
10 when locally distinct adhesive regions are to be able to be determined.
The device according to the invention can comprise several adhesive removal
devices, in particular belts, in order to be able to cover several adhesive regions,
for example. In particular two adhesive removal devices can be provided, which
15 correspond to the two opposite end regions of the tubular sack bodies. This
embodiment enables both open ends of the tubular sack bodies to be sealed
simultaneously.
To solve the object underlying the invention, the invention furthermore proposes a
20 method of the type named at the beginning, which is characterised in that the
adhesive applied by the adhesive application device in the space between the
individual tubular sack bodies is removed by means of an adhesive removal
9
device arranged below the adhesive region and separate from the transportation
device.
Here, it is preferably provided that the tubular sack bodies are sealed at at least
one open end by folding an end section of the fabric after applying adhesive. Thus
a sack sealed at at least one end is produced. Either only one 5 end or both ends can
be sealed.
Preferably the adhesive is removed by a powered belt or a powered roller.
10 A preferred development of the method provides that the adhesive removal device
is cleaned by means of a cleaning device, for example a brush. The superfluous
adhesive on the adhesive removal device is removed by one such cleaning device
and the adhesive removal device is thus cleaned.
15 Furthermore it is preferable that the sack body transportation device and the
adhesive removal device are powered together. In doing so a single drive device is
used that powers both the sack body transportation device and the adhesive
removal device, in particular the belt or the roller.
20 Furthermore it is preferable that the adhesive removal device, in particular the belt
or the roller, is powered in a direction parallel to the transport direction of the
transport device. In particular the belt is then moved in the same direction as the
tubular sack bodies.
10
A preferred development provides that the adhesive removal device, in particular
the belt or the roller, moves at the same speed as the tubular sack bodies. Thus the
adhesive is applied to the belt at intervals which correspond to the spaces between
the tubular sack bodies. This prevents the adhesive applied 5 in the spaces, for
example when it has not yet been separated from the tubular sack bodies, from
being pulled under a tubular sack body by the belt and unwantedly then sticking to
it, for example.
10 Furthermore it is preferred that the tubular sack bodies are on the belt. Thus the
belt can simultaneously be used to support of the tubular sack bodies during
transport.
In a further preferable embodiment, the belt is led between the tubular sack bodies
15 and a stationary plate. Thus the adhesive applied in the gaps is prevented from
ending up on the plate.
The invention is preferably used for sacks whose fabric consists of monoaxially
stretched polymer tapes, in particular polyolefin or polypropylene tapes.
20
The fabric of the tubular sack bodies can be essentially coated or uncoated,
wherein it is preferably provided that the outsides of the tubular sack bodies are
coated. Here, the coating preferably consists of the same polymer as the polymer
11
tapes. The coating can consist of a thin layer or polypropylene or a mixture of
polypropylene and polyethylene.
Within the scope of the invention, an extrudate of a polymer, in particular a
polyolefin, such as polypropylene, polyethylene or a mixture 5 of polypropylene
and polyethylene for example, can be used as adhesive. Here, the use of an
extrudate of the same polymer of which the sack fabric and, where applicable, its
coating are made, is particularly advantageous. This enables production of the
sack from one single material, which not only promotes recycling, but also is very
10 cost-effective and results in a stable product.
The invention is subsequently explained in more detail by using an exemplary
embodiment depicted in the drawings. In these Fig. 1 shows a schematic top view
of the device according to the invention, Fig. 2 a section view along the line II-II,
15 Fig. 3 a view of the transverse section according to arrow III.
In Fig. 1 it can be seen that a fabric tube 1 is fed to the device in the direction of
arrow 2 and is transported within a longitudinal transportation section 3 of the
device in the direction of arrow 2. Initially the fabric tube 1 is cut along cutting
20 lines 4, 5 and 6. The course of the cutting lines 4, 5 and 6 is depicted as a dotted
line to the left, wherein line 4 extends across the entire width of the fabric tube 1,
and lines 5 and 6 each run across the edges 7 of the fabric tube. The cuts running
along lines 4, 5 and 6 are made by means of a cutting device 8. The cutting device
12
8 comprises an internally situated tool, i.e. arranged between the fabric ply layers
of the fabric tube 1, which comprises rollers 9 for spacing the fabric ply layers and
a plate-shaped tool 10 arranged after the rollers 9 in the transport direction 2. The
plate-shaped tool 10 serves as a counterpart for the cutting knife, which acts on
the fabric from the outside. The cutting knives which operate 5 along cutting lines 5
and 6 are labelled with 11. The cutting knife operating along cutting line 4 is
labelled with 12 (Fig. 2). The cutting knives are able to be heated up and
moveably mounted, corresponding to double arrow 13, in order to be pressed on
the plate-shaped tool 10 by interposing the fabric.
10
In this way, cuts are produced in the fabric along cutting lines 4, 5 and 6. The cut
produced along cutting line 4 is labelled with 14 in a section of the tubular fabric
further forward. The cut 14 is thus produced only in the upper fabric ply layer or
front panel 18 of the sack (Fig. 2), while the lower fabric ply layer or the back
15 panel 19 of the sack remains untouched by this. The lateral incisions produced
along cutting lines 5 and 6 are labelled with 15 and 16 in a transported section of
the tubular fabric that has been transported further forward.
In the position indicated schematically by 17, the tubular fabric 1 is cut to length
20 by means of a further cutting device that is not depicted, in order to obtain
individual tubular sack bodies 20. Here the cut runs along the cutting line labelled
21. In the cutting to length along line 21, the fabric section 22 shown by shading
13
disappears. This fabric section can consequently be recycled by being supplied to
an extruder for producing fabric tapes.
By cutting away fabric section 22, a flap 23 is then exposed, which is formed
from the back 5 panel 19 of the sack.
In an alternative embodiment the formation of the flap 23 does not occur, such
that the cuts 4, 5 and 6 as well as the cutting knives 11 and 12 required therefor
are not provided.
10
At the end of the longitudinal transportation section 3, the tubular sack bodies 20
end up in a transverse transportation section 24, by being further transported in the
direction of arrow 25. The sack bodies 20 here have open ends 26 and 27. In the
transverse transportation section, the flap 23 (or in the alternative embodiment the
15 corresponding double-layered end section) of the sack bodies 20 folded forwards
along the fold line denoted by 28, i.e. on the surface of the upper fabric ply layer
visible in the drawing or the front panel 18 of the sack, and is joined to this
surface, for example by adhesion. This then results in the state of the sack body 20
labelled with 29.
20
A stationary adhesive application nozzle 30 is provided for sticking the flap 23 or
the end section of the sack body 20, said nozzle continuously applying adhesive to
the surface of the fabric. The adhesive application nozzle 30 is arranged after a
14
pressure roller 31 with which the flap 23 or the end section is pressed onto the
front panel 18 of the sack after folding, such that an adhesion takes place with the
use of an adhesive.
The cutting device 8 can be seen more easily in the section 5 view according to Fig.
2. The cutting device 8 comprises two rollers 9 that space the two fabric ply layers
13 and 14 of the fabric tube 1 apart from one another. The cutting device 8 further
comprises a subsequent plate 10 between the rollers 9 in the transport direction 2,
said plate being formed as a counterpart to the welding knife 12.
10
In the view according to Fig. 3, the arrangement of the adhesive application
nozzle 30 and the pressure roller 31 can be seen above the sack bodies 20.
Furthermore, it can also be seen that the sack bodies 20 are on a plate 32 or a table
in the transverse transportation section 24 and are moved on in this transport
15 direction 25 by a transportation device that is not depicted. In doing so, the plate
32 serves as a counterpart to the pressure roller 31 in order to be able to apply the
required pressure.
Furthermore, an adhesive removal device, namely a revolving belt 33, can be
20 seen, its moving run being arranged between the plate 32 and the sack body 20.
The belt is led downwards through suitable notches of the plate and diverted by
means of diversion rollers 34. The movement direction of the moving run of the
belt 33 is denoted by 35 and corresponds to the transport direction 25 of the sack
15
bodies 20. The movement speed of the belt 33 is chosen to be the same as the
transportation speed of the sack bodies 20. As can be seen in Fig. 1, the belt 33 is
arranged below the adhesive application nozzle 30, i.e. in the same edge region of
the sack bodies 20, in which the flap 23 or the end section of the sack body 20 is
folded and bonded. In this way, the adhesive emerging from the 5 nozzle 30 into the
space 36 between two sack bodies 20 that follow on from one another ends up on
the belt 33 and is removed by this. In order to remove the adhesive stuck to the
belt, a stripping device 37 is provided which works together with the run of the
belt 33 moving in reverse.
10
A roller can also be arranged instead of the belt 33, the roller being arranged
below the nozzle 33 and gathering the adhesive applied in the space as describe
above.
15 In the case of the adhesive in the space 36 getting caught on the two sack bodies
20 and thus not staying on the belt 33 and being removed by this, a thin film belt
is formed bridging the gap 36 and connecting the two sack bodies 20. This film
band can be cut off as near as possible to the edges of the sack, by means of a
knife 38 arranged afterwards, and led away. The described film belt can arise in
20 the use of a polymer, in particular polyolefin or polypropylene extrudate as
adhesive.

Claims:
1. Device for sealing sacks made of fabric, to which the tubular sack bodies
can be supplied, comprising an adhesive application device for the
continuous application of adhesive in an adhesive region and a
transportation device for transporting the tubular sack 5 bodies transversely
to their longitudinal axis through the adhesive region, such that adhesive
can be applied to a strip region of the tubular sack bodies, characterised in
that an adhesive removal device that is separate from the transportation
device is arranged below the adhesive region in order to remove the
10 adhesive applied by the adhesive application device in the space between
the individual tubular sack bodies, wherein the adhesive application device
is an extruder and a stationary sheet is arranged below the extruder in such
a way that the tubular sack bodies are guided between the extruder and the
sheet, wherein a folding device for folding a flap or an end section of the
15 fabric in the transportation direction is furthermore arranged after the
extruder and a pressure roller is subordinate to the extruder and is formed
in order to press the flap or the end section of the sack onto a front wall of
the sack after folding, such that through the use of the adhesive, an
adhesion takes place, wherein the adhesive removal device comprises a
20 powered, revolving belt which is arranged beneath a transportation level of
the tubular sack bodies and above the sheet and beneath the pressure
roller, and wherein the sheet preferably serves as an opposition element for
the pressure roller.
17
2. Device according to claim 1, characterised in that the adhesive removal
device is heat-resistant.
3. Device according to claim 1 or 2, characterised in that the side of the
adhesive removal device facing the adhesive application has an antiadhesive
5 coating.
4. Device according to claim 1, 2 or 3, characterised in that a cleaning device
is provided that is fitted to the adhesive removal device and interacts with
it is provided, for example a brush.
5. Device according to one of claims 1 to 4, characterised in that the adhesive
10 removal device is powered by means of the engine of the transportation
device.
6. Device according to one of claims 1 to 5, characterised in that the adhesive
application device is arranged to be stationary.
7. Method for sealing sacks made of fabric, in which the tubular sack bodies
15 are transported transversely to their longitudinal axis by means of a
transportation device, wherein the tubular sack bodies are spaced apart
from one another in the transportation direction and the sealing comprises
a continuous application of an adhesive in an adhesive region, wherein the
tubular sack bodies are guided through the adhesive region, such that
20 adhesive is applied to a strip region of the tubular sack bodies,
characterised in that the adhesive applied in the space between the
individual tubular sack bodies by the adhesive application device is
18
removed by an adhesive removal device arranged beneath the adhesive
region, the adhesive application device being separate from the
transportation device, wherein the adhesive application device is an
extruder and the tubular sack bodies are guided between the extruder and a
stationary sheet, wherein, after the adhesive application, 5 a flap or an end
section of the fabric is folded and the flap or the end section of the sack is
pressed onto a front wall of the sack by means of a pressure roller after the
folding, such that through the use of adhesive, an adhesion takes place,
wherein the adhesive is removed by a powered, revolving belt which is
10 guided under a transportation level of the tubular sack bodies and over the
sheet and under the pressure roller, and wherein the sheet preferably serves
as an opposition element for the pressure roller.
8. Method according to claim 7, characterised in that the adhesive removal
device is cleaned by means of a cleaning device, for example a brush.
15 9. Method according to claim 7 or 8, characterised in that the transportation
device and the adhesive removal device are powered together.
10. Method according to one of claims 7 to 9, characterised in that the
adhesive removal device, in particular the belt or the roller, is powered in a
direction parallel to the transportation direction of the transportation
20 device.
19
11. Method according to one of claims 7 to 10, characterised in that the
adhesive removal device, in particular the belt or the roller, moves at the
same speed as the tubular sack bodies.
12. Method according to one of claims 7 to 11, characterised in that the
tubular sack bodies 5 lay on the belt.
13. Method according to one of claims 7 to 12, characterised in that the fabric
consists of monoaxially stretched small polymer tapes, in particular
polyolefin or polypropylene tapes.
14. Method according to one of claims 7 to 13, characterised in that the outer
10 sides of the tubular sack bodies are coated.