Note: Descriptions are shown in the official language in which they were submitted.
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BAG FILLING APPARATUS AND METHOD FOR FILLING LOOSE MATERIAL
INTO A BAG
FIELD OF THE INVENTION
The present invention relates generally to bag filling and sealing apparatuses
for
packing loose material. More particularly, it concerns a bag filling apparatus
and
method for filling loose material into a bag and reducing considerably dust
emission
while at the same time keeping the inside of the bag free from dust in its
sealing
region.
BACKGROUND OF THE INVENTION
Bag filling apparatuses for packing loose material typically use a stationary
filling
chute positioned over the bag ready to be filled and sealing equipment for
sealing the
top of the bag once it has been filled with the dusty material. The sealing of
the bag
is usually performed by melting a top sealing region of the bag thereby
obtaining a
transverse seam sealing the bag. One problem encounters with such machine is
that
fluffy dust tends to be ejected from the bag into the surrounding environment
and
also to accumulate on the inside surface of the bag. Such dust contamination
come
from the air draft generated when the bag is filled up with the loose
material. The air
draft activates the dust contained in the material as the bag is filled and
allows the
dust to stick on the inside surface of the bag. Since the dust generally has a
higher
melting point than the material from which the bag is made, typically
polyethylene,
the dust acts as a thermal barrier, thus affecting the seal strength. While
many
attempts have been made by the industry to successfully prevent dust emission
and
the contamination of the sealing region of a bag with very dusty materials,
the
problem remains unsolved.
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Thus, there is still presently a need for a bag filling apparatus for filling
loose material
into a bag that successfully prevents dust contamination of the bag within a
sealing
zone.
There is also a need for a bag filling apparatus for filling loose material
into a bag
that successfully prevents dust emission outside the bag during and after the
feeding
of loose material into the bag.
Known in the art are US Patents nos. 3,928,940 (Fagniart); 3,707,172 (Obara);
4,096,894 (Guy); 4,109,792 (Greenawalt et al.); 4,182,386 (Alack); 4,308,710
(Sandberg); 4,526,214 (McGreggor); 4,648,432 (Mechalas); 5,349,996
(McGreggor);
5,413,157 (McGreggor); 5,531,252 (Derby et al.); 5,581,984 (Domke et al.);
5,704,197 (Gifford); 6,748,723 (Wadium et al.); and Japan Patent no. 07033257,
which disclose various apparatuses and methods for keeping the inside of a bag
free
from dust in its sealing region.
Also known in the art are US Patents nos. 4,081,004 (Harris); 4,537,013
(Tetenborg
et al.); 4,566,505 (Ruf et al.); 5,014,493 (West); 5,301,492 (Kader);
5,375,396
(Huwelmann); 5,466,894 (Naef); 6,065,271 (Nicastro); and 6,776,197 (De Crane),
which disclose various bag filling apparatuses and methods for packing loose
material.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a bag filling apparatus and
method for
filling loose material into a bag that satisfy the above-mentioned needs.
It is also an object of the invention to provide a bag filling apparatus and
method for
filling loose material into a bag, adapted to prevent accumulation of dust in
a sealing
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zone of the bag prior to sealing the same, thus providing a strong and
efficient
transverse seam sealing the bag.
According to the present invention, these objects are achieved with a bag
filling
apparatus for filling loose material into a bag, comprising a feeding hopper
having an
inlet for receiving the loose material and an outlet connected to a hollow
tube, which
extends along a substantially vertical axis. The hollow tube has an outlet to
discharge
the loose material from the feeding hopper into the bag. The hollow tube
comprises
an upper section connected to the feeding hopper and a lower section slideably
mounted over the upper section. The lower section is movable between a raised
position and a lower position where it extends into the bag. The lower
position is
used upon discharge of the loose material into the bag. The bag filling
apparatus
further comprises dust collecting means for collecting dust within the lower
section of
the hollow tube when the lower section is in the lower position and the bag is
filled
with the loose material. The bag filling apparatus further comprises means for
moving
the lower section of the hollow tube along the vertical axis between the
raised and
the lower positions.
According to the present invention, there is also provided a method for
filling loose
material into a bag, comprising the steps of:
a) providing a hollow tube connected to an outlet of a feeding hopper and
extending along a substantially vertical axis, the hollow tube having an
outlet to
discharge the loose material from the feeding hopper into the bag, the hollow
tube
comprising an upper section connected to the feeding hopper and a lower
section
slideably mounted over the upper section and movable between a raised position
and a lower position where the lower section extends into the bag, the lower
position
being used upon discharge of the loose material into the bag;
b) holding a bag open under the lower section of the hollow tube;
c) moving the lower section to the lower position;
d) feeding a certain amount of loose material to the feeding hoper;
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e) collecting dust within the lower section of the hollow tube when the lower
section is in the lower position and the bag is filled with the loose
material; and
f) moving the lower section to the raised position.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects and advantages of the invention will become apparent
upon
reading the detailed description and upon referring to the drawings in which:
Figure 1 is a perspective view of a bag filling apparatus according to a
preferred
embodiment of the present invention.
Figure 2 is a front view of the apparatus shown in Figure 1.
Figure 3 is a bottom view of the apparatus shown in Figure 1.
Figure 4 is an enlarged view of the encircled region of Figure 3.
Figure 5 is a perspective view of a bag filling apparatus according to another
preferred embodiment of the present invention.
Figure 6 is a side view of the apparatus shown in Figure 5.
Figure 7 is a front view of the apparatus shown in Figure 5.
Figure 8 is a perspective view of a bag opening device used with the bag
filling
apparatus shown in Figure 5, with some elements removed for clarity.
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Figure 9 is a side view of a bag being held by two skids for use with the bag
opening
device shown in Figure 8.
While the invention will be described in conjunction with examples of
embodiments, it
5 will be understood that it is not intended to limit the scope of the
invention to such
embodiments. On the contrary, it is intended to cover all alternatives,
modifications
and equivalents as may be included as defined by the appended claims.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In the following description, similar features in the drawings have been given
similar
reference numerals and in order to lighten the figures, some elements are not
referred to in some figures if they were already identified in a precedent
figure.
A bag filling apparatus according to the present invention is suitable for
packing
loose dusty material, such as concrete mix, peat moss, etc. into a bag which
is
preferably made of a thermoplastic material such as polyethylene. It may
conveniently be used with any suitable sealing apparatus known in the art.
As mentioned above, the apparatus is provided with a dust collecting system
for
collecting the dust that may be emitted into the environment or accumulate on
the
inner walls of the bag. The dust collecting system is used prior to performing
the
sealing operation of the bag and prevent dust contamination of the bag within
a
sealing zone. The bag filling apparatus is thus preferably installed close to
a bag
setting station (not shown) and a sealing station (not shown). Although not
illustrated,
both the bag setting station and the sealing station may be provided by the
bag filling
apparatus. Prior to performing the feeding operation by which the loose
material is
fed into the bag, a bag is placed and held open under the apparatus 1 at the
bag
setting station.
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Referring to either one of Figure 1 or 5, the bag filling apparatus 1
comprises a
feeding hopper 2 having an inlet 4 for receiving loose dusty material to be
filled into a
bag and an outlet 6. Preferably, the feeding hopper 2 is stationary. A hollow
telescopic tube 8 is mounted around the outlet 6 of the feeding hopper 2 and
extending therefrom along a substantially vertical axis 10. The hollow
telescopic tube
8 is used to orient the loose material into a bag 3 (as shown in Figure 5)
held open
under the apparatus 1. The telescopic tube 8 has an inlet 12 connected to the
outlet
6 of the feeding hopper 2 and an outlet 14 to discharge the loose dusty
material into
the bag 3. More specifically, the telescopic tube 8 has an upper tubular
section 16
and a lower tubular section 18 overlapping the upper section 16. The lower
section
18, which is preferably concentric to the upper section 16, is slideable along
the
upper section 18 between a raised position and a lower position, allowing the
lower
section 18 to get down into the bag during the filling process. The upper and
lower
sections 16, 18 are in a spaced apart relationship, thereby leaving an annular
space
there between. The annular space is closed at the top end of the lower section
18,
and is used as a dust collecting area 20, as described below.
The lower section 18 has two ports 21 connected to the dust collecting area 20
for
collecting dust when the bag is filled. Although two ports 21 are shown in the
Figures,
only one port 21 may be sufficient. As illustrated, a dust collecting duct 22
is
connected to each of the ports 21. The dust collecting ducts 22 are preferably
flexible
and may be operatively connected to a vacuum system (not shown).
The apparatus 1 further comprises a frame 28 extending substantially at the
level of
the feeding hopper 2 and a scissor lift assembly 26 mounted to the frame 28
for
moving the lower section 18 from its raised position to its lower position.
The scissor
lift assembly 26 is used to actuate the same. The scissor lift assembly 26
comprises
at least an upper rod 27 pivotally connected to a lower rod 29 by means of a
swivel
pin 31. The upper rod 27 is secured to the frame 28 whereas the lower rod 29
is
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secured to the lower section 18 of the telescopic tube 8. A pneumatic 24 (or
hydraulic
cylinder) is provided for opening and closing the scissor lift assembly 26,
thereby
raising or lowering the lower section 18 of the telescopic tube 8.
In the preferred embodiments illustrated, the scissor lift assembly 26
comprises two
pairs of upper and lower rods facing each other, and one pneumatic cylinder 24
interconnecting the swivel pins 31 of each pair.
Also preferably, and as illustrated in the Figures, the apparatus comprises
two
scissor lift assemblies 26, one on each side of the feeding hopper 2.
Any other suitable assembly for moving the lower section from its raised
position to
its lower position may be used instead for that purpose.
The lower section 18 of the hollow tube 8 is moved to its lower position when
the bag
3 is held open under the telescopic tube 8 and is ready to be filled up. When
the bag
3 is filled up, the lower section 18 stays down and the vacuum system, through
the
dust collecting area 20 and the dust collecting ducts 22, removes the dust in
the
lower section 18, thus indirectly removing dust near a top sealing section of
the bag
3. The zone of the bag 3 to be sealed is therefore protected from
contamination by
dust. The lower section 18 is retracted when the dust is removed. Then, the
top end
of the bag 3 is sealed at the sealing station by any conventional sealing
means
known in the prior art.
In accordance with another preferred embodiment of the invention and referring
to
Figures 5 to 7, the bag filling apparatus further comprises a closing device
32 for
closing the bag 3 over the lower section 18 of the hollow tube 8, thereby
preventing
dust emission outside the bag 3 during the feeding operation and improving the
protection of the inner walls of the bag against dust accumulation.
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Preferably, the closing device 32 is a removable collar being shaped to mate
with the
lower section 18 to insure a tight seal of the bag 3 around the lower section
18. The
collar 32 may comprise two brackets 34, 36 movable between a first position
{as
shown in Figures 5 to 7) where the brackets 34, 36 tighten the bag 3 over the
lower
section 18 and a second position (not shown) where the brackets 34, 36 are
positioned away from the lower section 18. As better shown in Figure 7, the
brackets
34, 36 are used to close the upper portions 38 of the bag 3 on the lower
section 18 to
prevent dust emission, thus increasing efficiency of the dust removing
process. The
brackets 34, 36 are moveable between the first and second positions by means
of
actuators 50 mounted on another frame 30, hereinafter referred to as the lower
frame 30, which extends generally at the level of the lower position of the
lower
section 18. When the filling process is completed and the dust removed, the
brackets
34, 36 are retracted away from the lower tube 18 for a next bag 3 to be held
open
under the telescopic tube 8.
Preferably, the surface 58 of the brackets 34, 36 which comes in contact with
the bag
3 when the lower section 18 is in the lower position is covered by a soft
coating, such
as rubber to prevent damage to the bag 3.
Now turning to Figure 8 and 9 in order to keep the bag open under the
telescopic
tube 8, a bag opening device is preferably mounted to the lower frame 30. The
top of
the bag 3 is secured to skis 52 which move the bag 3 along a skid platform
(not
shown) to the bag setting station. At the bag setting station, the skis 52 are
fixed to
two supports 54. Each of the supports 54 extends on one side of the lower
section
18 and is movable along arrow 56 by means of guiding arms 46 controlled by
actuators 42, thereby opening or closing the bag 3. Of course, any other
suitable bag
opening device may be used instead.
While embodiments of this invention have been illustrated in the accompanying
drawings and described above, it will be evident to those skilled in the art
that
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changes and modifications may be made therein without departing from the
essence
of this invention.
