EP2498983B1 - Apparatus and method for forming stacks of bags - Google Patents

Description

The invention relates to a device for forming stacks of bags according to the preamble of claim 1 and to a method according to the preamble of claim 8.

Bags are made individually in bag making machines. Foil bags are provided with welds and usually separated at the same time. For the production of paper bags hoses are first formed from paper webs and separated pieces of tubing. At the leading end of each paper tube piece, a bottom is formed.

The bags thus formed are stacked in a stack forming apparatus so that the bags can be discharged in batches and packaged and / or further processed.

Such a device for producing stacks is in the Laid-open publication DE 30 40 021 A1 disclosed. A transport device is shown, which fixes a single bag due to a negative pressure with the lower run of a suction belt from above and pulls it to a collection point. The bag is released from the suction belt with a release device by a knockdown presses the bag onto the collection point. The bag is pulled off the suction openings of the suction belt. After a stack having a desired number of bags has been formed in this way, a conveyor belt on which the stack has been formed is moved. Now a new stack is created at a free collection point of the conveyor belt.

A disadvantage of this device is that the feed rate and thus the speed of the bag machine are severely limited. If the feed speed were increased, then at the beginning of a new stack, the previous stack could not have been sufficiently removed. In the production of foil bags, this disadvantage is acceptable, since the production speed is limited by other factors.

However, in the production of paper bags, where speeds in excess of 1,000 bags per minute may occur, this limitation of stacking limitation is undesirable.

The DE 20 2007 002 477 U1 Therefore, there are two collection facilities, but this leads to a large space requirement and should also be expensive.

The DE 201 20 735 U1 discloses an apparatus and a method according to the preamble of claims 1 and 8, respectively.

The object of the present invention is therefore to propose an apparatus and a method for forming stacks of bags, in which the stacking speed is sufficiently high and which cause a small space requirement.

The object is achieved by a device according to the preamble of claim 1, which additionally comprises the features of the characterizing part of claim 1.

Accordingly, a separating device is provided, which can be introduced into or above the stack in the collection point and divides the stack into a first and a second stack.

A separator can be introduced at a high speed in the stack or above the stack already formed. Preferably, this separator is placed above the stack when the stack has reached the desired number of bags. The following bags are thus placed above the separator. Portions of the bag rest on the separator. The resulting first stack, which is located below the separator, can now be removed without the second stack started above the separator is significantly affected. Since the introduction of the separator can be done within a few milliseconds, this process is usually completed before the first bag of the second stack reaches the collection point. The separator does not need to cover the entire surface of a bag by far. It is sufficient if only one edge, preferably the edge running ahead during the transport of the bag, is covered.

It is particularly advantageous if the separating device comprises at least one holding device, with which at least the lower bag of the second stack is durable. With this holding device so the begun, second stack can be fixed in its position. As a result, the influence of the first stack during its removal is additionally minimized.

In an advantageous embodiment of the invention, the separating device comprises at least one wedge-shaped finger. Such a wedge-shaped element can be easily inserted between two bags, without causing problems. This shape is advantageous when the first bag of the second stack is already thrown while the element is still moving.

In a preferred embodiment of the invention, the separating device comprises at least one bore which can be acted upon by negative pressure. This suction hole thus serves as a holding device. This embodiment lends itself to because there are several suction openings on devices for bag production and therefore there is already a vacuum supply device, for example in the form of a vacuum pump.

Further embodiments of the invention will become apparent from the description and the claims.

Fig. 1

Seitenansicht einer erfindungsgemäßen Vorrichtung

Fig. 2

Vorrichtung gemäß Figur 1 während des Bildens eines ersten Stapels

Fig. 3

Vorrichtung gemäß Figur 1 nach dem Einbringen einer Trenneinrichtung

Fig. 4

Vorrichtung gemäß Figur 1 während des Bildens eines zweiten Stapels

Fig. 5

Vorrichtung gemäß Figur 1 während des Abtransports des ersten Stapels

Fig. 6

Vorrichtung gemäß Figur 1 nach dem Abtransport des ersten Stapels

Fig. 7

Vorrichtung gemäß Figur 1 nach während des Rückziehens des Schiebers.

Fig. 8

Vorrichtung mit einer alternativen Verschieberichtung der Trenneinrichtung

The individual figures show:

Fig. 1

Side view of a device according to the invention

Fig. 2

Device according to FIG. 1 while forming a first stack

Fig. 3

Device according to FIG. 1 after introducing a separator

Fig. 4

Device according to FIG. 1 while forming a second stack

Fig. 5

Device according to FIG. 1 during the removal of the first batch

Fig. 6

Device according to FIG. 1 after the removal of the first batch

Fig. 7

Device according to FIG. 1 after during the retraction of the slider.

Fig. 8

Device with an alternative direction of displacement of the separator

Fig. 1 shows a device 1 according to the invention for the formation of stacks 3 of bags 2. These bags 2 are manufactured in a device for the production of bags, the storage cylinder 4 is indicated. With the Abschälfinger 5 individual bags are lifted from the storage cylinder and deflected onto the or the transport belt 7 of the transport device 6. Each bag is carried forward with its folded end 13. The folded end 13 forms the bottom and points to the outside, so that the bag rests with its back completely on the conveyor belt.

The transport device 6 comprises a plurality of adjacent conveyor belts 7, which rotate at the same speed. They run over the discs 8, 9, and 10, whereby more or less discs can be provided. The bags 2 can be fixed to the transport belt 7 in various ways during transport. One possible embodiment is the suction by means of negative pressure, as it is already in the DE 30 40 021 A1 is described. Here, the conveyor belt suction openings whose respective distance is greater than the largest, can be produced with the bag machine bag length. The transport belt 7 are led to suction boxes 11, 12, which are each connected to a vacuum source, but this is not shown in detail. The disc 10 is also designed so that the suction openings of the conveyor belt 7 can be acted upon by a negative pressure.

In order to also be able to guide bags of variable length completely around the disc 10, the suction box 12 comprises an extension 14, which is displaceable in the direction of the double arrow 15. The dashed line shows the groove 16 of the suction box 12 (not shown) extending recess 16 is shown. As long as the suction opening of the conveyor belt is above this depression 16, the bag can be held. Only at the end of the depression is a drop of the bag 2 possible. With the extension 14 and the stop 17, which limits the transport path of the bag 2, 18 movable in the direction of the double arrow. In this case, the stop 17 may be rake-shaped or fork-shaped and engage between the individual conveyor belt 7. The extension 14 and the stop 17 are displaceable by means of a suitable adjusting device (not shown in detail). This adjusting device can be a spindle-spindle nut combination, which can be driven by hand and / or by motor, for example by an electric motor. Other adjustment arrangements are conceivable. The adjusting device can be attached to a wall or support of the machine frame, not shown.

In order not to damage the bag when dropped after the removal of the negative pressure, the extension 14 still includes a further opening 19 which is acted upon by an overpressure. The bags 2 are thus repelled when the suction openings of the conveyor belt 7 pass through this opening.

The so transported to the stop 17 and there ejected bag 2 are placed in the collection point 20 to a stack 3. The collection point 20 comprises a collection table 21, which comprises a plurality of parallel webs, which are not visible in the illustration shown. These webs again engage through the stop 17. The collecting table 21 is movable along the double arrow 22 and can be moved downwards after each bag throw by a small distance, which is correlated with the thickness of the bag 2. In the manner described is now a stack 3 of bags 2 until it includes the desired number of bags. Such a condition is in the FIG. 2 shown.

In order to be able to start a new stack now, separating fingers 23 representing separating devices are now moved into the region of the collecting point 20 above this stack. The FIG. 3 shows the device after the introduction of the separating fingers 23. For this purpose, the separating fingers 23 of a holding device 24, for example a holding plate, are arranged displaceably. The displacement corrections are indicated by the double arrow 25. As a displacement drive 26 may be provided a piston-cylinder unit. However, it is every other, very fast acting drive used. Also advantageous would be linear motors, which in addition to their speed also have a very high positioning quality. The displacement drive 26 is supported on the holding device 24. The introduction of the separating fingers 23 takes place so fast that the next following bag 2 'can be dropped onto the separating fingers 23. In this way, the separating finger separates the finished first stack from the newly started stack 3 '.

With the growth of the stack 3 'and the separating fingers 23 must be moved simultaneously to the collecting table 21 down. For this purpose, the holding plate 24 in the vertical direction of movement, which is illustrated by the double arrow 27, be displaced. Again, various suitable displacement devices are conceivable. The holding plate may be operatively connected to the collecting table 21 to allow a common displacement. The holding plate and / or the separating fingers 23 with the displacement drive 26 must be displaceable relative to the collecting table in this case in order to set the desired stack height can. However, this adjustment must be made only before production. In contrast, the displacement of the collecting table and the holding plate takes place during bag making. Accordingly, a motor-driven, precisely positionable displacement device is to be provided here. Finally, the support plate 24 must be displaceable synchronously with the stop 17 and / or the extension 14 along the double arrow 28 for adaptation to the bag length.

The first stack 3, which is now below the stack 3 'which is being set up, can now be removed.

For this purpose, a slider 29 is provided, which comprises a plurality of bars (only the front is visible). At right angles thereto, abutment elements 31 are provided, which can grip like a fork between the webs of the collecting table 21. The abutment elements 31 are also surmounted by a wedge 30 or a plurality of wedges, which can be introduced into the clearance created by the separating fingers 23 between the stack 3 and the stack 3 '. The slider 29 is supported on a support device 32, which in turn is connected to a carriage 33. This carriage 33 is shown along a rail assembly 34, for example, a single rail is shown here, in the direction of the double arrow 35 slidably. The rail arrangement is also displaceable in the direction of the double arrow 36, so that the vertical position of the slider 29 is adaptable to the position of said free space. After adjusting to this position, what in the FIG. 4 is shown, the slider can be moved along the direction of displacement 35. This is in the FIG. 5 shown. During the shifting operation, the new stack 3 'can be formed on the surface facing the stack 3'. The slider can thus take over the function of the collecting table 21 during this time.

It is essential that with a holding device at least the lower bag of the stack 3 'in its position relative to the collection point 20 is durable, so that the started stack 3' is not moved. Any shift of bags will result in poor stack quality, which should be avoided. For this reason, the separating fingers 23 shown in the embodiment shown comprise at the top openings 37, which can be acted upon by a negative pressure. This negative pressure can already be switched when the first bag 2 'of the new stack 3' rests on the separating finger 23. This can lead to an improvement in the quality of the stack 3 'during its formation. The opening 37 and the channels 38 and the suction line 39 are in the FIG. 1 shown. The holding device may for example also be designed mechanically. One or more grippers could detect at least the lower bag. Also on the basis of other physical principles working holding devices are conceivable.

Thus, an electrostatic attraction for the purposes mentioned can be exploited. This is particularly applicable when the bags include, for example, viewing windows made of a plastic material.

The stack 3 is displaced by the slider opposite to the transport direction x of the bag 2 just before it is dropped off. This direction points away from the separating fingers 23, so that the lower bag 2 'of the new stack 3' struck and its damage is avoided. The stack 3 is moved to a storage device 40, from where it can be further transported or removed. After the stack 3 has completely left the collecting table 21, it is raised again and moved under the lower bag of the new stack 3 '. This condition is in the FIG. 6 shown. The stack 3 'is now on the collecting table 21, so that the separating fingers 23 can be brought back into the starting position, which in the FIG. 7 is shown. Also, the slider 29 can be moved back to its original position, so now again the state according to FIG. 1 is made.

The individual components necessary for the described method and the described device can be arranged in different ways and optionally joined together without departing from the inventive idea. The said displacement devices and the necessary drives can be configured in various ways. Particularly noteworthy, however, is the use of linear motors, which allow rapid shifts and can also be positioned very accurately. Linear motors can be used for all displacement devices described above.

The FIG. 8 shows a device in which the separating finger 23 is not carried out horizontally, but vertically displaceable. This is advantageous because there is no risk during the introduction of the separating finger to move the bag. In addition, with the discarding of the upper bag 2 of the stack 3, the separating finger 23 can be moved so that it is not necessary to wait until the falling bag completely rests on the stack. So this brings a time advantage. In the upper position is the separating finger between or above the suction channels 12 and / or the extension 14, so that the formation of the stack 3 is not disturbed.

Thus, with the illustrated and described device, stacks of bags can be produced and transported away with a desired number of bags, without the collection process having to be interrupted in the device or continued with at least reduced speed. LIST OF REFERENCE NUMBERS 1 Apparatus for forming stacks of bags 2 bag 3 stack 4 storage cylinder 5 Abschälfinger 6 transport means 7 conveyor belts 8th disc 9 disc 10 disc 11 suction box 12 suction box 13 Turned end of the bag 3 14 Extension of the suction box12 15 Displacement device of the extension 14 16 Extending indentation 17 attack 18 Direction of movement of the stop 17 19 opening 20 collection 21 collecting table 22 Direction of movement of the collecting table 21st 23 separating finger 24 holder 25 double arrow 26 displacement drive 27 Movement direction of the holding plate 24th 28 double arrow 29 pusher 30 wedge 31 contact element 32 support means 33 carriage 34 rail arrangement 35 Displacement direction of the slider 36 double arrow 37 openings 38 channel 39 suction 40 Bin Setup x Transport direction of the bag shortly before it is dropped

Claims (8)

1. Apparatus for forming stacks (3) of bags (2), preferably of paper bags, which can be fed in individually, comprising:

   - at least one first transporting device (6) with which individual bags (2) can be transferred,

   - a collecting point (20) to which the bags (2) can be fed by the transporting device (6) and in which a stack (3) of bags (2) can be produced,

   - a detaching device with which the bags (2) can be detached from the transporting device (6) and can be dropped onto the collecting point (20),

   wherein at least one separating device (23) is provided which can be introduced in or above the stack (3) into the collecting point (20) and divides the stack into a first stack (3) and a second stack (3'), characterized in that a slide (29) having a plurality of bars and contact elements (31) arranged at right angles thereto is provided, with which slide (29), after the separating device (23) has been introduced, the first stack (3) can be transported out of the collecting point (3), wherein, during the displacement operation, the new stack can be formed on that surface of the slide (29) which faces the stack.
2. Apparatus according to the preceding claim, characterized in that at least one wedge projects over the contact elements, which wedge can be inserted into the clearance, which is produced by the separating device (23), between the first stack (3) and the second stack (3').
3. Apparatus according to either of the preceding claims, characterized in that the separating device comprises at least one holding device with which at least the lower bag of the second stack can be held.
4. Apparatus according to one of the preceding claims, characterized in that the separating device comprises at least one wedge-shaped finger.
5. Apparatus according to the preceding claim, characterized in that the wedge-shaped finger can be introduced above the first stack before the first bag of the second stack can be dropped into the collecting point.
6. Apparatus according to one of the preceding claims, characterized in that the separating device comprises at least one bore to which a negative pressure can be applied.
7. Apparatus according to one of the preceding claims, characterized in that the separating device comprises at least one gripper.
8. Method for forming stacks of bags, preferably of paper bags, which are fed in individually, in which:

   individual bags are transferred by at least one first transporting device,

   the bags are supplied by the transporting device to a collecting point and a stack of bags is produced there,

   the bags are detached from the transporting device by a detaching device and dropped onto the collecting point,

   wherein a separating device is introduced in or above the stack into the collecting point and divides the stack into a first and a second stack, characterized in that a slider (29) having a plurality of bars and contact elements (31) arranged at right angles thereto is used, after the separating device has been introduced, to transport the first stack (3) out of the collecting point (3), wherein, during the displacement operation, the new stack is formed on that surface of the slide (29) which faces the stack.

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