Device for forwarding sacks or like containers

A device for forwarding sacks or like containers from a filling station to further processing stations includes a device for retaining the sack in its filling position, a conveyor for forwarding the filled sack, a device for lowering the filled sack down onto the conveyor, while simultaneously closing the sack mouth by seizing it from the outside and stretching out the edges thereof along a plane coincident with the forwarding direction of the sack, and a device for supporting and advancing the sack.

BACKGROUND OF THE INVENTION 
This invention relates to a device by which sacks or similar containers can 
be forwarded from a filling station to further processing stations, or to 
storage or to elsewhere, and more particularly, though not exclusively, to 
such a device suitable for handling sacks or like containers filled with 
usually pulverulent materials having a poor consistency and marked 
volatility features, and requiring therefore that the sack be kept in a 
vertical position, not only by a support at the bottom of the sack, but 
also by propping up the sack in the area of its filling opening. Such 
opening is to be sealed directly after the filling of the sack, and is to 
be maintained in such a sealed condition during the course of all 
subsequent operations, to thereby prevent a loss of material from the 
sack, as well as any possibility of pollution of the surrounding 
environment. 
There are known systems by which one sack at a time is removed in a 
flattened condition from a stack of sacks, the removed sack is then 
automatically conveyed to a filling station, where the sack mouth is 
opened and slipped over a filling sleeve and retained thereagainst by 
suitable means, e.g. in the form of jaws acting from the exterior of the 
sack. Once the sack or like container is filled, it is transferred to a 
conveyor by which the sack is forwarded to subsequent processing stations, 
whereat, e.g., the sack edges are sewn, tags for the identification of the 
sack contents are applied, etc. 
In the situation mentioned above, i.e. when the sacks are filled with 
particularly volatile materials, it is essential that the filled sack be 
transferred very slowly from the filling attachment or nozzle to the 
forwarding conveyor, and moreover that the sack mouth be immediately 
sealed and maintained in such sealed condition until the edges of the sack 
mouth are sewn, to prevent any loss of material and also to prevent any 
resultant pollution of the environment. 
Such operations are heretofore performed manually, with a consequently high 
labour requirement, and also with the possibility of mistakes being made 
in performing the operation in the correct sequence. 
SUMMARY OF THE INVENTION 
Thus, the object of the present invention is to provide a device, having a 
particularly simple design and operating in a particularly reliable 
manner, which is able to automatically perform all of the above noted 
operations, while ensuring that the filled sack will be handled, from the 
filling station up to final mouth closing operation, e.g. sewing, without 
any, even small, loss of sack contents. 
According to the present invention, the above objects are achieved by 
providing a device which comprises, in association with a filling station, 
with means for retaining the sack in its filling position, and with a 
conveyor for forwarding the filled sack, means for lowering the filled 
sack down onto the conveyor, while simultaneously closing the mouth of the 
sack, by grasping and stretching outwardly the edges of the sack along a 
plane coincident with the forwarding direction of the sack. The device 
also includes means for supporting and advancing the mouth of the sack 
during at least a portion of forwarding movement of the sack. In 
particular, the means for lowering the sack and closing the mouth thereof 
may advantageously include at least two pairs of seizing and supporting 
elements in the form of pressers, each presser pair being coaxially 
arranged. The presser pairs are controllably movable in directions to 
approach each other to thereby engage portions of the sack mouth. The sack 
mouth is then retained between the pressers, and the engaged portions are 
guided while the sack is lowered and the sack mouth is being closed. In 
more detail, portions of the sack outwardly of the jaws which retain the 
sack against the filling sleeve are acted upon by the pairs of pressers. 
Such portions extend along a diameter of the sack mouth directed parallel 
to the sack forwarding direction. The presser pairs are then synchronously 
moved along trajectories such that the sack is lowered onto the forwarding 
conveyor, while the presser pairs are simultaneously moved away from each 
other, in the direction of such diameter, thus bringing the edges of the 
sack mouth into mutual contact, i.e. closing the mouth of the sack. 
As previously mentioned, after the sack is lowered onto the forwarding 
conveyor, the upper portion of the sack is engaged by supporting and 
advancing means independent of the pressers, and essentially including a 
pair of conveyors fitted on swinging arms. The conveyors can be moved 
together, in the manner of pliers, against the already closed sack mouth, 
before the forwarding motion of sack is started. 
The device is operated by follow-up and control means, by which a suitable 
operating sequence of the movements of the various components is 
established, to ensure that the sack is always supported and guided 
without the danger of excessive stresses or breakage of the sack.

DETAILED DESCRIPTION OF THE INVENTION 
The device as shown is particularly, though not exclusively, designed to 
operate in cooperation with an already known system by which sacks are 
removed while flattened, one at a time, from a stack of sacks and are then 
automatically transferred to a filling unit, whereat the sack mouth is 
opened and slipped over a filling sleeve or nipple and fastened thereon. 
In any case, the sack mouth is slipped over a filling sleeve 10 (see FIG. 
1) extending from the bottom of a feeding hopper 12, and retained thereon 
by a pair of jaws 14, that are kept pressed against the sack walls until 
the end of the filling operation. Then the filled sack is lowered onto a 
forwarding conveyor 16, e.g. in the form of an endless band conveyor, by 
which the sack is conveyed to subsequent operating stations. As previously 
stated, when the materials being sacked have marked volatility features, 
it is most important that the filled sacks be lowered onto the band 
conveyor 16 as gently as possible, and that the mouth of the sack be 
closed as soon as it is removed from the filling sleeve 10. 
The edges of sack mouth are engaged by the retaining jaws 14 against sleeve 
10 over only a portion of the whole circumference of filling sleeve 10, 
thereby leaving free two lengths of sack mouth on opposite sides of filler 
10, such lengths extending in a direction coincident with the forwarding 
direction of the sack. Therefore, such free lengths can be engaged by two 
pairs of seizing and supporting elements in the form of pressers 20, 22 
and 24, 26. Each pair of pressers are axially aligned. Each presser is 
axially driven in a direction perpendicular to sack forwarding direction, 
e.g. by hydraulic or pneumatic cylinder-piston units 28, 30 and 32, 34. As 
shown in FIGS. 1, 2 and 3, the presser pair 20 and 22 is brought into 
engagement with the downstream portions of the sack mouth as viewed in the 
forwarding direction of the sack, while the presser pair 24 and 26 is 
brought into engagement with the upstream portions of the sack mouth. 
Pressers 20, 22, 24 and 26 are therefore operated by the respective units 
28, 30, 32 and 34 in such a manner as to retain and support the mouth of 
the sack after it is filled, at a time when the sack mouth is still 
grasped by jaws 14. This position is shown in FIG. 3a, wherein the filler 
10 and the jaws 14 are omitted for the sake of clarity. 
The pressers 20, 22, 24 and 26, along with the respective driving units 28, 
30, 32 and 34, are mounted on arms 36, 38, 40 and 42, respectively, that 
can be lowered by conventional mechanical means (not shown), to thereby 
lower the presser pairs 20, 22 and 24, 26, and the sack supported thereby, 
toward the conveyor band 16. Simultaneously, presser pair 20 and 22, units 
28 and 30, and arms 36 and 38 are drawn apart from presser pair 24 and 26, 
units 32 and 34, and arms 40 and 42, until the opposite edges of the sack 
mouth are brought into positions of firm mutual contact, as shown in FIGS. 
1, 2 and 3b. Such motion makes it possible to lower the sack 18, without 
any impact, down onto the conveyor 16, while simultaneously closing the 
sack mouth, as soon as the sack leaves the filler sleeve 10, to thereby 
prevent any loss of the sack contents. The above simultaneous dropping and 
diverging motion can be achieved by conventional mechanical motion control 
devices, e.g. suitably configured cam-shaped grooves 44 and 46 (see FIG. 
1), within which move in a positively guided manner cam followers 
associated with arms 36, 38, 40 and 42. By suitably modifying the 
dimensional parameters of above components, e.g. by substitution of parts 
thereof, it is possible to adapt the motion of the presser pairs to 
particular sizes of handled sacks. 
Obviously, the above described operations are to be performed in a suitable 
sequence, e.g. by follow-up and control means not shown, and as 
diagrammatically represented in FIG. 4, wherein the step of closing 
presser pairs 20, 22 and 24, 26 is indicated by reference number 48, the 
next step of opening jaws 14 is indicated by reference number 50, and the 
next step of providing the lowering and diverging motion of the presser 
pairs is indicated by reference number 52. 
Once the sack 18 is lowered onto the forwarding conveyor 16, then conveyor 
16 can be started. However, it is essential to maintain the sack mouth in 
the previously attained closed condition while also supporting the sack 
near its mouth. Provided for achieving such function according to the 
present invention are a pair of endless band conveyors 54 and 56 which 
operate in vertical planes and which are supported on arms 58 and 60, 
respectively, which swing about vertical axes. Thus, conveyors 54 and 56 
can be closed, or moved together, after the manner of pliers, to grasp the 
sack 18 near the mouth thereof at a position below the presser pairs 20, 
22 and 24, 26. 
In more detail and with particular reference to FIGS. 1 and 2, the arms 58 
and 60 are fitted on hollow supports 62 and 64, respectively. Supports 62 
and 64 can be swung in either direction about shafts 66 and 68, 
respectively, which also support the driven pulleys of conveyor bands 54 
and 56, respectively. Shafts 66 and 68 are driven by pulleys 70 and 72 in 
synchronization with one another and with the motion of forwarding band 
conveyor 16. The hollow supports 62 and 64 of arms 58 and 60, respectively 
are driven or pivoted by gears 74 and 76, respectively, in mesh with a 
rack 78. 
Referring now to FIG. 4, the sequence of operations comprises, after the 
sack 18 is lowered onto conveyor 16, the step 80 of operating rack 78 to 
cause arms 58 and 60 to move together toward opposite sides of the mouth 
of sack 18, and due to the engagement of arms 58 and 60 with conveyors 54 
and 56, causing conveyors 54 and 56 to swing together and grasp 
therebetween the sides of the mouth of sack 18, as shown in FIGS. 1 and 
3b. Then, in the next step 82 the pressers 20, 22, 24 and 26 are opened 
and disengaged from the sack 18, and raised and returned to their 
respective initial positions, ready for engagement with the next sack. 
Then, in step 84, conveyors 16, 54 and 56 are advanced in synchronization. 
Downstream of conveyor bands 54 and 56, the sack continues to be conveyed 
by three stationary bands, of which only the forwarding band acting as a 
prolongation of band 16 is indicated at 86 in FIG. 2. Thus, the conveyors 
16 and 54, 56 are ready for engagement with the next sack, obviously after 
arms 58 and 60 are opened to allow for the passage therebetween of the 
next filled sack. As shown in FIG. 2, the sack 18 is conveyed to a station 
88 where the sack mouth is sewn. The sack is then possibly conveyed to a 
station 90, where all air trapped in the sack is evacuated in a vacuum 
chamber through the sewing holes, and finally the sack may be conveyed to 
a station (not shown) where an identification tag is applied to the sack. 
These further stations are of known conventional type, whereby no further 
description thereof is made. 
I will thus be appreciated that the device according to the invention, 
having an unusually simple and inexpensive design, makes it possible to 
automatically and reliably perform the operations of forwarding sacks or 
similar soft, or even hard, containers. On the other hand, the 
hereinbefore disclosed inventive concepts could obviously be placed into 
practice, with the same results, even by making many changes and 
modifications to the above specifically disclosed preferred embodiment, 
without departing from the spirit and scope of the invention, as defined 
in the appended claims.