EP2805633B2 - Trays made of conductive plastic material and device and method for automatically discharching trays filled with rod-shaped articles - Google Patents

Description

The present invention relates to trays for receiving rod-shaped products of the tobacco processing industry, comprising a tray body formed by a rear wall, two at least substantially parallel and spaced-apart side walls and a bottom wall, forming a receiving space for the products that is open to the front and top, wherein the tray can be designed as a shaft tray.

The invention further relates to a tray emptying device for automatically emptying trays filled with rod-shaped products in a production or packaging machine in the tobacco-processing industry, comprising a feed device for feeding trays filled with rod-shaped products, an emptying station with an emptying position for emptying the trays overhead, a Removal device for transporting away the emptied trays and a transfer device for transporting the trays within the tray emptying device during an emptying cycle, as well as a method for automatically emptying trays filled with rod-shaped products, comprising the steps of feeding trays filled with products by means of a feed device, transporting the trays from the feed device into an emptying position of an emptying station by means of a transfer device, so that the trays are upside down in the emptying position , overhead emptying of the trays, transporting the empty trays by means of the transfer device from the emptying position to a removal device, and removing the empty trays by means of the removal device.

The trays described are used in particular in the tobacco processing industry when processing rod-shaped products. Tobacco sticks, cigarettes, filter rods and in particular filter rod segments or the like are kept in containers, the so-called trays, in particular for transport and storage. The containers can be designed as standard trays with a single receiving space for all products or as shaft trays in which the products lie in several separate shafts. For further processing of the stored products, these are passed on to downstream devices, such as packing machines or the like, or channeled into an existing mass flow.

Nowadays, such trays are usually made of plastic such as polystyrene (PS) or acrylonitrile-butadiene-styrene (ABS), since this material is stable and at the same time light and inexpensive. Such trays are for example in DE-Gbm. 1 882 950.

A downstream device in which trays are used is a tray emptying device, with the help of which rod-shaped articles, which are stored in trays for various reasons, are reintroduced into the production process. For this purpose, the tray emptying devices are combined with production machines to form a production arrangement for carrying out corresponding production processes, which include cigarette production, filter production and also their packaging.

Known tray emptying devices have transfer devices for handling or handling the trays, which are designed as a pivoting mechanism. With the known swivel mechanism, all trays, that is to say the full trays and the empty trays, are handled during the emptying cycle. An emptying cycle comprises the removal of the full trays from the feed device, the overhead emptying of the full trays in the emptying station and the delivery of the empty trays to the removal device.

Such tray emptying devices are for example in DE 10 2008 027 636 described.

In the known tray emptying devices, the problem arises that, during or after emptying, rod-shaped products remain in the tray, although the tray should have been completely unloaded in the tray emptying device. Rod-shaped products stick to the bottom and / or wall of the tray, since an electrostatic field has formed in the tray, which prevents the rod-shaped products from falling out. Such an electrostatic field is formed due to the fact that the trays are made of plastic, a dielectric material, through friction. Friction occurs on one side when the rod-shaped Products are filled in the tray, rubbing against the walls and bottom of the tray. The tray walls or bottom and rod-shaped products are charged with different charges, which leads to the formation of an electrostatic field that prevents the trays in the emptying device from being completely emptied, as actually desired. Further charging takes place when the trays come into contact with other plastic objects during transport. For example, the conveyor belts on the one hand for the feed device and on the other hand for the removal device are usually made of plastic. The friction between the tray and the conveyor belt creates an electrical charge. Such a load is particularly relevant when the tray is transferred from the feed device to the emptying station when the tray is stopped by means of a stopper for the purpose of transferring it to the emptying device while the conveyor belt of the feed device continues to run under the tray. The drier the ambient air, the greater the resulting electrostatic charge.

So far, this problem has been taken into account in that the empty trays are checked by one person and any remaining rod-shaped products are removed manually. With an increasing degree of automation in production, which in particular should lead to a reduction in costs, there is an increasing lack of people in the entire process who could exercise such a control function.

It is therefore desirable to ensure that, if possible, no stick-shaped products remain in the tray after the emptying process.

To this end, the WO2011 / 090395 Two measures are proposed, on the one hand, to blow ionized compressed air into the bottom of the trays to neutralize the charge, and on the other hand to use an insert or an insert made of a conductive material inside the tray in order to essentially prevent the occurrence of electrostatic charge.

The provision of a device for blowing in ionized compressed air is structurally complex and associated with increased costs. The provision of inserts or inserts is also expensive, since an additional work step of inserting the insert is required in the production of the trays, which in turn increases the costs elevated. There is also the risk that the insert or insert will become detached from the tray, get into the machine and cause damage.

The object of the present invention is therefore to provide a tray whose complete emptying can be ensured and which at the same time is simple and inexpensive to manufacture.

According to the invention, this object is achieved by a tray with the features of claim 1. By using electrically conductive plastic as the tray material, any charge that arises can be dissipated immediately. There is no need to apply an additional layer, insert or the like. The tray can be constructed very easily. An electrically conductive plastic in the sense of the invention is a plastic which - unlike plastics usually considered to be excellent insulators - has an electrical conductivity of at least 10 ^-10 S cm ^-1 . In the context of the invention, electrically conductive plastics are understood to mean the so-called intrinsically conductive polymers which per se have conductivity.

This works particularly well when the entire tray is made of electrically conductive plastic. The tray is advantageously designed in one piece and manufactured using the injection molding process. In this way, a very stable tray is obtained, which at the same time is inexpensive to manufacture. Existing molds can also continue to be used for the production of trays, since only the material changes while the tray shape remains identical.

The tray according to the invention can also be a shaft tray, ie a tray in which the products lie in a plurality of shafts separated from one another by partition walls. The partition walls are also advantageously made of electrically conductive plastic.

The electrically conductive plastic is an intrinsically conductive polymer, in particular a doped intrinsically conductive polymer. Among the intrinsically conductive polymers are in particular cis-polyactetylene (cis-PA), trans-polyacetylene (trans-PA), poly (paraphenylene) (PPP), polythiophene, polypyrrole, poly (para-phenylene-vinylene) (PPV) and polyaniline (PANI) should be mentioned. Particularly preferred because one is several powers of ten Polymers that have higher conductivity are those that are doped, ie into which a small amount of foreign atoms are incorporated.

The conductive plastic tray according to the invention has a greatly reduced adhesion of the article to its inner walls. This has an advantageous effect on the filling and emptying processes, but this could possibly have a disadvantageous effect with regard to a safe transport of the upright trays filled with rod-shaped articles, in particular during acceleration and / or deceleration processes.

In a further development of the tray according to the invention it is therefore provided that the inside of the rear wall of the tray is inclined by at least 1 degree from the perpendicular to the perpendicular outside, the wall thickness of the rear wall increasing from top to bottom towards the bottom wall.

Due to the rear wall tapering towards the open upper side, there are also advantages in the manufacture of the plastic collar, namely a so-called demolding bevel is hereby created.

In a further development of the tray according to the invention it is further provided that the bottom wall of the tray is inclined on its inside by at least 1 degree from the horizontal relative to the horizontal outside, the wall thickness of the bottom wall decreasing from front to back to the rear wall.

The inner sides of the rear wall and the bottom wall are preferably inclined by approximately the same angular amount, so that the included angle is approximately 90 degrees.

As a result of the developments described above, it is now possible to safely transport the articles in upright trays without the conveying means, in particular for the transport of full trays, being inclined as is customary in tray filling devices and tray emptying devices. In order to ensure safe filling or emptying of the trays in the tray filling devices or in the tray emptying devices, the trays for filling or emptying are inclined by means of a swivel device in such a way that the inside of the rear wall of the tray lies in the same, preferably vertical plane as the upstream or downstream rear wall of the intermediate or buffer storage of the tray filling device or the tray emptying device.

The object is also achieved by a tray emptying device of the type mentioned at the outset, in which at least one charge-dissipating element is provided on at least one device selected from a feed device, emptying station, removal device and transfer device, which is designed and configured to establish contact between the tray and the the grounded machine base frame.

As stated above, it is very advantageous if the trays are made of electrically conductive plastic, since this enables the charge generated by friction to be dissipated. In order to achieve the desired effect, it is necessary that the charge is diverted from the tray. Usual machines and devices in the tobacco processing industry have a machine base frame to which the individual components and parts are attached. This machine base frame is always earthed. It is therefore ideally suited to dissipate the charge that has arisen. To do this, it is necessary to establish a conductive connection between the trays with cargo and the machine base frame. According to the invention, this is provided by at least one charge-removing element which is attached either to the feed device, to the emptying station, to the removal device or to the transfer device. The charge-dissipating element or the charge-dissipating elements can in particular be designed as contact surfaces made of metal. Silver, copper and iron, which are good electrical conductors, are particularly suitable as metals.

In a preferred embodiment of the tray emptying device, its transfer device has a pivoting mechanism that executes a pivoting movement limited to 180 ° with a pivoting cassette that can be pivoted about a stationary pivot axis S and that is designed and set up for fixing, pivoting and releasing the trays, the pivot axis being the charge discharge element is. A particularly good discharge is guaranteed if the swivel mechanism is also provided with a copper braid. Since the swivel movement of the cassette is limited to 180 °, problems caused by twisting the braid are eliminated.

It is particularly advantageous if as little electrostatic charge as possible is generated in the entire process. According to an advantageous embodiment, it is therefore provided that the feed device and / or removal device is or are designed as a conveyor belt, the conveyor belt being made of an electrically conductive plastic. In this way, the charging that arises from the friction between the tray and the conveyor belt is largely avoided.

Finally, the object is also achieved by a method of the type mentioned at the outset, in which the trays of the present invention are used as trays and in which charge is discharged in at least one of the method steps. With such a method, the static charge in the trays is reduced to such an extent that stick-shaped products sticking in the trays after the emptying process should essentially be ruled out. The method is particularly effective and at the same time simple, since no expensive additional devices, for example for deionization, have to be provided.

Fig. 1

eine perspektivische Darstellung eines erfindungsgemäßen als Schachtschragen ausgebildeten Schragens,

Fig. 2

eine Ausführungsform eines nicht erfindungsgemäßen Schragens,

Fig. 3

eine weitere Ausführungsform eines nicht erfindungsgemäßen Schragens,

Fig. 4

eine Seitenansicht der erfindungsgemäßen Entleereinrichtung mit einem auf der Zuführeinrichtung befindlichen Schragen in der Abholposition,

Fig. 5

die Entleereinrichtung gemäß Figur 4 mit dem in eine Kassette aufgenommenen Schragen während der vertikalen Aufwärtsbewegung und

Fig. 6

die Entleereinrichtung gemäß Figur 4 mit einer in die Entleerposition geschwenkten Kassette.

Further useful and / or advantageous features and configurations emerge from the subclaims and the description. A particularly preferred embodiment and the principle of the method are explained in more detail with reference to the accompanying drawing. In the drawing shows:

Fig. 1

a perspective view of a tray according to the invention designed as a shaft tray,

Fig. 2

an embodiment of a tray not according to the invention,

Fig. 3

another embodiment of a tray not according to the invention,

Fig. 4

a side view of the emptying device according to the invention with a tray located on the feed device in the pick-up position,

Fig. 5

the emptying device according to Figure 4 with the tray received in a cassette during the vertical upward movement and

Fig. 6

the emptying device according to Figure 4 with a cassette pivoted into the emptying position.

The one in the Figures 1 to 3 Trays shown by way of example are used in the tobacco processing industry in particular for the transport and storage of rod-shaped products such as cigarettes, filter rods or the like. for use. The ones in the Figures 4 to 6 The emptying device shown by way of example serves for the successive emptying of containers filled with rod-shaped products into an emptying magazine or the like. It is pointed out, however, that the features and combinations of features described below can also be implemented in combinations other than those shown.

the Figures 1 to 3 show a shaft tray 1 which has two side walls 3 and 4, a bottom wall 5 and a rear wall 6 to form a tray body 2. The side walls 3, 4 are arranged essentially parallel and spaced apart (may have draft bevels, which cannot be seen in the figures) and laterally delimit a receiving space 7 defined by the tray body 2. The bottom wall 5 delimits the receiving space 7 downwards. The shaft trays 1 are usually designed to be open at the front and at the top. Of course, front walls and cover elements can also be provided. The tray body 2 can be formed in one piece or in several pieces. The receiving space 7 itself can be subdivided. Preferably, several shaft walls 8 for dividing the receiving space 7 into several shafts 9 are detachably or firmly connected to the tray body 2. The shaft walls 8 can also be formed integrally with the tray body 2. The shaft walls 8 run parallel and at a distance from one another or from the side walls 3, 4.

The tray 1 can also be designed as a standard tray without shaft walls 8.

The tray is made of electrically conductive plastic, which is a so-called intrinsically conductive polymers commercially t, via the se has conductivity.

The one in the Figures 2 and 3 The tray shown is an example not according to the invention and is made from a plastic with the addition of additives. Fibers of an inorganic substance are included as an additive. Such fibers can in particular be stainless steel fibers or carbon fibers. The conductivity in the direction of the fibers is significantly higher than perpendicular to it. The in Fig. 2 The trays shown are formed essentially parallel to the longitudinal extent of the tray side and partition walls 3, 8. The in Fig. 3 The trays shown run essentially parallel to the longitudinal extent of the tray bottom 5.

The ones in the Figures 4 to 6 The emptying device 10 shown comprises a feed device 11, a removal device 12, an emptying station 32 and a transfer device 13. The feed device 11 is used to feed and store trays 14 made of electrically conductive material filled with products. The feed device 11 is arranged above the removal device 12 and, like the removal device 12, runs essentially horizontally. Essentially horizontal also expressly includes a slight inclination with an angle greater than 0 ° and less than 5 ° in relation to a horizontally spanned plane, such that the feed device 11 slopes slightly in the direction of the transfer device 13, so that the containers 14 with respect to a vertical orientation inclined by the corresponding angle α stand on the feed device 11. An inclination of 3 ° from the vertical is preferably selected. As a result, the products within the tray 14 rest securely against the rear wall 6 of the tray 14. The evacuation device 12 serves to evacuate the emptied trays 16. By means of the transfer device 13, the full trays 14 can be transported from a pick-up position 17 into the area of an emptying magazine 18 and back to a delivery position 19. The emptying magazine 18 can be arranged as part of the emptying station 32 or as a separate part under the emptying position. In the area of the pick-up position 17 there is a stopper 15 which holds the tray in the pick-up position 17 until it has been picked up by the transfer device. Meanwhile, the feed device 11 continues below the tray 14, as a result of which electrostatic charge builds up in the tray in conventional devices. To prevent such electrostatic charge is the feed device 11 is designed as a conveyor belt, the conveyor belt being made of a conductive plastic.

The transfer device 13 comprises a cassette 21 which is designed to be movable and pivotable vertically up and down. The vertical and pivoting movements can be carried out directly or indirectly through the cassette 21. Furthermore, the cassette 21 is designed and set up to hold a tray 14, 16 during the entire emptying process. This means that the cassette has devices for holding and / or gripping the trays 14, 16, by means of which the trays 14, 16 are fixed within the cassette 21 in a defined position, which can also be inclined to the vertical. Pneumatic gripping elements are preferably provided. The holding of the trays 14, 16 themselves can be realized, for example, by metallic spring elements or the like. Of course, all other conventional holding and / or gripping mechanisms made of conductive material can also be used. A pick-up element 22 is optionally assigned to the cassette 21 for picking up or picking up the full trays 14 from the feed device 11. The pick-up element 22 is furthermore set up and designed to position the full tray 14 within the cassette 21 so that it can be fixed in the “middle product” position. The "middle product" position, also known under the term "constant edge", is advantageous for handling different product lengths in the course of a format changeover. The pick-up element 22 can furthermore also have a push-off element (not shown), by means of which the ejection of the emptied tray 16 from the cassette 21 is supported. The push-off element can also be provided as a separate device.

In order to carry out the vertical movements from the pick-up position 17 to the transfer position 20 in the area of the pivoting device 27 and back to the transfer position 19, the emptying device 10 preferably has a lifting device 23 as part of the transfer device 13. The lifting device 23 comprises vertically running guide rails 24 or the like, on which or in which a lifting fork 25 or the like is guided and a drive unit 26. Furthermore, the transfer device 13 comprises a pivot device 27. The pivot device 27 is between the transfer position 20 and the emptying position arranged and set up and designed to carry out an overhead pivoting movement of the cassette 21 holding the full tray 14 over the emptying magazine 18 as well as the cassette 21 holding the then emptied tray 16. The pivot device 27 is arranged at the upper end of the guide rails 24 and forms a swivel head. The pivoting device 27 has a latching device 28 and a rotatable and stationary shaft 29, the latching device 28 being mounted on the shaft 29. The shaft 29 itself is fixedly but rotatably mounted on a frame or the like. The shaft 29, together with the cassette 21, forms the charge-removing element, with the aid of which the charge present in the tray can be diverted via the base frame 33 of the emptying device 10. In addition, a copper braid (not shown) can be provided in the area of the shaft 29, which supports the discharge of charge.

The latching device 28 comprises a plurality of latching bolts (not shown) which can be actuated, for example, by means of pneumatic cylinders (also not shown) or the like. This means that the movably mounted locking bolts from a retracted waiting position in which the cassette 21 can be coupled in or out during the transfer from the lifting device 23 to the pivoting device 27 and back, into a locking position in which the cassette 21 is fixed to the pivoting device 27 is connected, and are movable back. In other words, the cassette 21 can be detached from the lifting device 23 and connected to the pivoting device 27 and vice versa. Of course, the locking of the cassette 21 on the pivoting device 27 and the corresponding unlocking can also take place in other conventional ways, provided the conductive connection between the pivoting device 27, the cassette 21 and the tray 14 is established. The distance between the axis of rotation D of the shaft 29 and the cassette 21 which is rotatably or pivotably mounted on the shaft 29 by means of the latching device 28 is designed to be small. This means that the latching device 28 is very short in terms of its structural shape, so that the cassette 21 describes a very narrow envelope curve with a small radius during the pivoting movement. Ideally, the cassette 21 is arranged in the immediate vicinity of the shaft 29 or directly on it. A drive 30 for executing the pivoting movement is assigned to the transfer device 13 and is arranged as an extension of the shaft 29.

The pick-up position 17 for the full trays 14 and the delivery position 19 for the emptied containers 16 can be at different positions. Preferably, however, the pick-up position 17 corresponds to the delivery position 19. As a result, the picking up of a full tray 14 from the feed device 11 into the cassette 21 and the delivery of an emptied container 16 from the cassette 21 can take place at the same time. In the preferred embodiment, both the pick-up position 17 and The delivery position 19 is also at the same level, namely at the level of the feed device 11. The lifting device 31 for transporting the emptied containers 16 from the delivery position 19 to the removal device is designed separately from the lifting device 23 for transporting the full trays 14 from the collection position 17 to the emptying position and back to the delivery position 19. However, it is also possible to provide a single lifting device for the entire transport of the trays 14, 16.

In the following, the procedural principle is based on the Figures 4 to 6 described in more detail, the description only representing a particularly preferred variant and other process sequences of course also falling within the scope of protection of the claims:

At least one full tray 14, but preferably several full trays 14, are arranged or stored on the feed device 11. The trays 14 have a narrow side on the feed device 11, which slopes slightly in the direction of the transfer device 13, so that the trays 14 are transported at an angle α to the vertical in the direction of the transfer device 13 into the pick-up position 17. The trays 14 can of course also be transported without being inclined. In each case a full tray 14 is transported from the pick-up position 17 to the emptying position in the area of the emptying magazine 18. The transport is preferably carried out in that the full tray 14 is pulled through the pick-up element 22 into the cassette 21 and positioned there. After the tray 14 has been fixed in the cassette 21, either the tray 14 itself or the cassette 21 is pivoted through an angle to the vertical which is greater than the angle α. With this overall inclination by the angle β to the vertical, the cassette 21 with the tray 14 is moved vertically upwards into the area of the emptying magazine 18 by means of the lifting device 23.

In the area of the transfer position 20, the cassette 21 is released from the lifting device 23 and connected to the pivoting device 27. For this purpose, the locking bolts of the locking device 28 are moved from a waiting position into the locking position, so that the cassette 21 is firmly connected to the shaft 29 of the pivoting device 27. The shaft 29 is connected at the same time to the machine base frame 33, so that a charge discharge Any electrostatic charge present in the tray 14 takes place. By rotating the shaft 29, the pivoting device 27 executes a pivoting movement, so that the tray 14 is overhead above the emptying magazine 18. The closing element of the tray 14 is opened so that the products fall down from the container 14 into the emptying magazine 18. Since the electrostatic charge is discharged shortly beforehand via the shaft 29 and the machine base frame 33, there is no longer any attraction between products and trays 14, so that the tray 14 is completely emptied and no products on the floor 5 or on the walls 3, 4, 6 of the slope remain. After the tray 14 has been completely emptied, the cassette 21 pivots back with the emptied tray 16. The cassette 21 with the emptied tray 16 is released from the pivoting device 27 and reconnected to the lifting device 23. The lifting device 23 transports the emptied tray 16 down to the delivery position 19. During the entire emptying process from the pick-up position 17 into the area of the emptying magazine 18 and back into the delivery position 19, the tray 14, 16 is in the up and down movable and pivotable cassette 21 held.

As soon as the cassette 21 is again in the delivery position 19 after emptying a tray 14, 16, which corresponds to the pick-up position 17, a new full tray 14 is picked up by the feed device 11 and positioned in the cassette 21, while at the same time the one in the cassette 21 located emptied trays 16 is pushed or pushed out of the cassette 21. The pushing out or ejecting can take place through the full tray 14 and / or through a push-off element. The emptied tray 16 is pushed out of the cassette 21 onto the lifting device 31, by means of which the emptied tray 16 is transported from the level of the feed device 11 down into the area of the removal device 12 and delivered to it.

As already mentioned, not all of the steps mentioned are necessary for the preferred execution of the method. It is crucial for a simple and reliable method that the tray 14, 16 is held permanently in the cassette 21 during the entire emptying process, that is to say during the transport and the emptying. In addition, for complete emptying it is necessary that the electrostatic charge generated in the process on the tray 14, 16 is discharged.

Claims (8)

1. Tray (1) for receiving rod-shaped articles of the tobacco-processing industry, comprising a tray body (2) formed by a rear wall (6), two side walls (3, 4) arranged at least substantially parallel and spaced-apart from each other and a bottom wall (5) providing a receiving space (7) for the products which is designed to be open to the front and above, wherein the tray (1) may be designed as a shaft tray, characterised in that the tray (1) is at least partially constructed of electrically conductive plastic material, wherein the electrically conductive plastic material is an intrinsically conductive polymer, in particular a doped intrinsically conductive polymer.
2. Tray (1) according to claim 1, characterised in that the entire tray (1) is constructed of electrically conductive plastic material.
3. Tray (1) according to claim 1 or 2, characterised in that it is constructed in one piece and is manufactured by injection moulding.
4. Tray (1) according to any one of claims 1 to 3, characterised in that the rear wall (6) of the tray (1) is inclined on its inside by at least 1 degree from the perpendicular with respect to the vertical outer side, wherein the wall thickness of the rear wall (6) increases from top to bottom towards the bottom wall (5) and/or that the bottom wall (5) of the tray (1) is inclined on its inside by at least 1 degree from the horizontal with respect to the horizontal outer side, wherein the wall thickness of the bottom wall (5) decreases from front to rear towards the back wall (6).
5. Tray discharging device (10) for automatically discharging trays (1, 14) filled with rod-shaped articles according to any one of claims 1 to 3, into a production or packaging machine of the tobacco-processing industry, comprising a feed device (11) for feeding in trays (14) filled with rod-shaped articles,

   a discharge station (32) with a discharge position for overhead emptying of the trays (14),

   a removal device (12) for transporting away the emptied trays (16) and

   a transfer unit (13) for transporting the trays (14, 16) within the tray discharging device (10) during a discharge cycle,

   characterised in that on at least one device, selected from feed device (11), discharge station (32), removal device (12) and transfer unit (13), at least one charge discharging element is provided, which is configured and adapted to establish a contact between the tray (1) and the earthed machine base frame (33).
6. Tray discharging device (10) according to claim 5, characterised in that the transfer device (13) has a pivoting mechanism executing a pivoting movement limited to 180° with a pivot cassette (21) pivotable about a fixed pivot axis S which is configured and adapted for fixing, pivoting and releasing the trays (14, 16), wherein the pivot axis S is the charge discharging element.
7. Tray discharging device (10) according to claim 5 or 6, characterised in that at least one of a feed device (11) and removal device (12) is configured as a conveyor belt, wherein the conveyor belt consists of an electrically conductive plastic material.
8. Method for automatically discharging trays (14) filled with rod-shaped articles, comprising the steps

   - feeding in trays (14) filled with rod-shaped articles by means of a feed device (11),

   - transporting the trays (14) from the feed device (11) into a discharge position of a discharge station (32) by means of a transfer unit (13), so that the trays are overhead in the discharge position, overhead emptying of the trays,

   - transporting the empty trays (16) by means of the transfer unit (13) from the discharge station (32) onto a removal device (12), and

   - transporting away the empty trays (16) by means of the removal device (12),

   characterised in that the trays (14, 16) are trays according to any one of claims 1 to 3 and that charge discharging takes place in at least one of the method steps.

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