EP2283285B1 - Cooling tunnel and method for operating the same - Google Patents

Description

The invention relates to a cooling tunnel, comprising a treatment room separated from the outside environment, an introducer sheath for introducing objects to be cooled into the treatment room, a discharge sheath for discharging objects from the treatment room, a plurality of successive treatment positions within the treatment room for supplying them cooling articles with a cooling medium, in particular cooling air, and a conveying device for transporting the objects to be cooled from the introducer to the exit lock, wherein the conveyor passes through the individual treatment positions and has a first portion passing through several treatment positions extending from the introducer sheath to a reversal position extends, and a plurality of treatment positions passing through the second section, which extends from the reversing position to the discharge lock. Furthermore, the invention relates to a method for operating a cooling tunnel according to the preamble of claim 12.

A cooling tunnel according to the preamble of claim 1 and a corresponding operating method according to the preamble of claim 12 are known from FR 2 793 006 A1 known. More cooling tunnels are out of the US 2,474,069 A and the DE 100 17 408 A1 known. The objects to be cooled, for example milk products stacked on pallets, are conveyed continuously from the treatment position to the treatment position in the known cooling tunnels by means of a conveyor and are cooled by lateral injection of cooling air.

Since a simultaneous supply of cooling air from opposite sides has proven to be less effective, the objects to be cooled or the pallets must be rotated on the conveyor either by means of a turntable 180 degrees or it must be provided a reciprocal air supply. Both are structurally complex.

If objects or batches of objects with different desired cooling times are to be cooled in such cooling tunnels, the problem is that, if the set cooling times are strictly adhered to, objects or batches with shorter set cooling times are often cooled longer than necessary, whereby the throughput of the cooling tunnel drops. If, on the other hand, higher priority is given to throughput, some items or batches are inevitably cooled too short, that is, they fall short of the actually desired set cooling time, which can have a negative effect on product quality.

Continuous cooling tunnels are therefore economical only for purposes in which the desired cooling times of the individual objects do not vary too much. For larger throughputs, some optimization can be achieved by parallel operation of multiple conveyors in a cooling tunnel.

To cool objects with different target cooling times is in the EP 1 455 151 B1 proposed a discontinuous cooling tunnel. In this case, the individual treatment positions branch off from a main funding path. Each object is transported with the conveyor before the respective treatment position and stored there. After sufficient cooling of the article this is returned to the conveyor and transported on. In this way, each article can be treated according to its individual cooling time and then discharged with the conveyor from the cooling area. However, such a configuration is complicated because a corresponding transport mechanism is required for each branch from the main conveying path to a treatment position. In addition, a relatively large footprint is required because the main conveyor to reach the individual treatment positions must always be kept free. Although it is possible to treat articles or batches with greatly differing desired cooling times with such cooling tunnels, without this causing individual articles or batches to block the throughput of the cooling tunnel too much or to cool it too quickly. In the case of homogeneous nominal cooling times, however, the throughput of discontinuous cooling tunnels is significantly lower than in the case of the continuous cooling tunnels explained above, since the conveying device represents a bottleneck.

Against this background, the invention has the object to provide a cooling tunnel that allows for variable target cooling times a high throughput.

This object is achieved by a cooling tunnel according to claim 1. The cooling tunnel according to the invention is characterized in particular by the fact that the conveying device has a return section which is arranged inside the treatment space in front of the discharge lock and connects a delivery-side area of the second section to an insertion-side area of the first section in order to selectively discharge or further cool objects.

As a result, objects with greatly different target cooling times can be introduced into the cooling tunnel in any order and the required target cooling time can be correspondingly cooled, without objects with higher target cooling times stopping the throughput of objects with shorter desired cooling times. The conveyor allows with the first and second sections and the return section a circulation for the objects to be cooled, with the return section in front of the discharge lock a switch is provided, which makes it possible to auszuschleusen sufficiently cooled items, but not enough cooled items to continue to cool ,

The conveyor can be controlled so that a feed is only made if it is necessary for discharging finished-cooled objects or to change the treatment position.

Advantageous embodiments of the invention are specified in further claims.

According to an advantageous embodiment, the first and second sections of the conveyor are arranged side by side in the common treatment space, wherein outflow areas for supplying cooling medium to the individual treatment positions on opposite side walls of the Treatment room are located. This allows a compact design and efficient use of the cooling medium. In addition, it is not necessary to rotate the objects to be cooled for the purpose of applying cooling medium from opposite sides about their vertical axis. Elaborate turntables on the conveyor can thus be omitted. Also adjacent portions with opposite directions of blowing, which would lead to flow losses or require delimitations with each other avoided.

Preferably, an air outlet between the first and second sections of the conveyor, whereby a good air flow to the objects to be cooled and thus a high cooling effect is achieved.

In principle, the second section of the conveying device can connect directly to the first section of the conveying device at the reversing position, it being possible for means to be provided in order to maintain the original orientation of the objects to be cooled. According to an advantageous embodiment of the invention, however, a transfer device for transferring objects from the first section of the conveyor to the second section of the conveyor is arranged at the reversing position, whereby a parallel arrangement of the first and second sections is made possible with a small distance. The footprint of the cooling tunnel remains so low.

Furthermore, the first portion and the second portion of the conveyor may have separately drivable portions, wherein at the end of each portion of the first portion, a transfer device for transferring objects to the second portion is arranged. As a result, different conveying paths can be realized in the cooling tunnel. By means of additional transfer devices between the first and second sections, as it were, abbreviations are created, over which articles with shorter residual cooling times can overtake those with longer residual cooling times. This allows a high degree of flexibility, which makes it possible to achieve a high throughput while maintaining close tolerances with respect to the desired cooling times.

Separately controllable outflow regions for supplying cooling medium are preferably assigned to the subregions. This allows the cooling tunnel to be adapted to varying throughput quantities. For example, with low throughputs Partial areas are switched off and accordingly energy is saved. This is further promoted by arranging the sections in separate treatment rooms, which are separated from each other by bulkheads. Furthermore, it is possible to realize different cooling processes by means of an air technology separate for the subregions.

According to a further advantageous embodiment of the invention, the first section of the conveyor at least in a subsequent to the introducer sheath portion for each treatment position on an individually controllable single-user drive. As a result, the objects to be cooled can be dammed up in this area. A further promotion takes place only if necessary. This can reduce the number of product movements. In addition, the energy efficiency can thus be optimized in particular in the case of a cooling tunnel consisting of several partial areas with low throughput quantities by superfluous partial areas being switched off by concentrating on the one or more partial areas.

The cooling tunnel according to the invention preferably further comprises a control device for controlling the individual sections of the conveyor as well as possibly existing section sections. The control device is configured such that a time account for the required target cooling time is assigned to each item introduced. Based on the cooling time account and the operation of the conveyor, the position of each item can be determined. If it is determined in the control device that an object is located in front of the return section, it is checked whether its cooling time account has expired. If this is the case, the object in question is ejected by operating the second section. Otherwise, the article is transferred to the first section of the conveyor by operation of the return section. As a result, a fully automatic operation of the cooling tunnel can be realized.

In the presence of a plurality of reversing positions can be further determined via the control device, whether for a particular object of the conveying path should be abbreviated. In this case, the control device transmits a corresponding signal to the relevant transfer device. In the control device a decision logic suitable for this purpose is stored, with which it is checked whether the object is to be transferred to the second section or to stay in the first section.

The invention further provides a method for operating a cooling tunnel according to claim 12, which is particularly suitable for the operation of the above-described cooling tunnel. The method according to the invention relates to a cooling tunnel with a circulation conveyor running through successive treatment positions, as well as an introducer sheath and a discharge sheath. According to the invention, objects with different desired cooling times are subsequently transferred to the circulation conveyor via the introducer sheath. Each item is assigned a time account with a target cooling time, on which the accumulated dwell time in the cooling tunnel is recorded. If an item reaches a position in front of the exit lock, the cooling time account is used to decide whether the item is to be dispensed through the exit lock or remains on the circulating conveyor. Expires the target cooling time while staying in the cooling tunnel, an execution of the subject matter is caused, with possibly upstream objects for which the target cooling time has not expired, are passed by the exit lock.

According to an advantageous embodiment of the method, the dwell times for different feed directions of cooling medium are recorded separately on the cooling time account. As a result, a more uniform cooling can be achieved.

If the circulating conveyor device has at least one branch for shortening the conveying path, the method according to the invention can be modified in such a way that it is decided on the basis of the cooling time account of several objects whether an article passes through the abbreviation branch or not. As a result, articles with a shorter target cooling time can be passed through the cooling tunnel more quickly, while at least a portion of the articles with higher residual cooling times need not be moved or at least less frequently.

As already explained above, it is also possible to accumulate objects in a first section of the conveyor.

Figur 1a

eine schematische Ansicht eines ersten Ausführungsbeispiels für einen Kühltunnel nach der Erfindung,

Figur 1b

eine schematische Ansicht eines zweiten Ausführungsbeispiels für einen Kühltunnel nach der Erfindung,

Figur 2

eine schematische Ansicht eines dritten Ausführungsbeispiels für einen modifizierten Kühltunnel mit mehreren Teilbereichen,

Figur 3

eine Ansicht von oben auf die Fördereinrichtung eines Kühltunnels nach Figur 2,

Figur 4

eine Schnittansicht quer zur Förderrichtung eines ersten und zweiten Abschnitts der Fördereinrichtung des Kühltunnels nach Figur 3, und in

Figur 5

eine Darstellung zum Ablauf des erfindungsgemäßen Verfahrens.

The invention will be explained in more detail with reference to embodiments shown in the drawing. The drawing shows in:

FIG. 1a

a schematic view of a first embodiment of a cooling tunnel according to the invention,

FIG. 1b

a schematic view of a second embodiment of a cooling tunnel according to the invention,

FIG. 2

FIG. 2 is a schematic view of a third exemplary embodiment of a modified cooling tunnel with a plurality of partial regions, FIG.

FIG. 3

a top view of the conveyor of a cooling tunnel after FIG. 2 .

FIG. 4

a sectional view transversely to the conveying direction of a first and second portion of the conveyor of the cooling tunnel after FIG. 3 , and in

FIG. 5

a representation of the sequence of the method according to the invention.

The embodiments illustrated in the figures relate to cooling tunnel 1 for cooling objects 10 such as dairy products and the like by means of a cooling medium. Typically, the articles 10 are stacked on pallets 11, which are flowed at different treatment positions within the cooling tunnel 1 with cooling air.

The in FIG. 1a shown cooling tunnel 10 has a relation to the outside environment separated treatment chamber 20. Within the treatment room 20 are several consecutive treatment positions 21.1 to 21.8, in which the on the pallets 11 stacked objects 10 are transported by means of a conveyor 30 before. At the treatment positions 21.1 to 21.8 are outflow areas 22.1 to 22.8 for applying the objects to be cooled 10 with cooling medium.

About an introducer sluice 23 to be cooled objects are introduced into the treatment chamber 20 and passed to the conveyor 30. Furthermore, a discharge lock 24 is provided, via which the articles 10 are led out of the cooling tunnel 1 after treatment with cooling medium. The conveyor 30 is arranged such that it passes through the successive treatment positions 21.1 to 21.8, whereby at the in FIG. 1 illustrated embodiment, each object to be cooled 10 all treatment positions 21.1 to 21.8 passes. However, this does not automatically mean that each article 10 to be cooled must remain at each treatment position 21.1 to 21.8 for an equal time interval. Rather, the feed of the conveyor 30 can be adjusted flexibly, so that different residence times result for the objects 10 at individual treatment positions, as will be explained in more detail below.

The conveyor 30 has first section 31 and a second section 32, which are delimited by a reversing position 33 against each other. Each section passes through multiple treatment positions 21.1 to 21.4 and 21.5 to 21.8. While the first section 31 extends from the introducer sheath 23 to the reversing position 33, the second section 32 extends from the reversing position 33 to the discharge lock 24. Both sections are arranged parallel to each other in the illustrated embodiment, but have opposite conveying directions, so that the Introductory lock 23 and the exit lock 24 are adjacent. At the in Fig. 1b In the variant shown, the introducer sheath 23 and the discharge sheath 24 are arranged at opposite ends of the cooling tunnel 1. Due to the circulation conveying principle of the conveyor 30, the arrangement of the locks 23 and 24, however, for example, also be done on the corner. In addition, more than a total of two locks 23 and 24 can be provided if necessary.

Furthermore, the conveyor 30 has a return section 34. This is arranged immediately in front of the discharge lock 24 and after the last treatment position 21.8 of the second section 32 and, if required, allows a transfer of articles 10 from the second section 32 to the first section 31. As a result, articles 10 can optionally be discharged or further cooled. The section can be designed, for example, as a driven roller conveyor with raisable and lowerable rollers, so that, depending on its position, an object transported on the second section 32 is picked up and branched off to the first section 31 or transported on to the discharge lock 24.

At the reversing position 33, a transfer device 35 for transferring articles 10 from the first section 31 of the conveyor to the second section 32 of the conveyor is arranged. The transfer device 35 can be configured as a roller conveyor with rollers driven transversely to the sections 31 and 32. Converted articles 10 or pallets 11 with them thus retain their original orientation when transferred from the first section 31 to the second section 32.

Since the outflow regions 21.1 to 21.4 assigned to the first section 31 and the outflow regions 21.5 to 21.8 assigned to the second section 32 are arranged in each case on opposite side walls 25 and 26 of the treatment space 20 parallel to the two sections 31 and 32 of the conveyor 30, the articles become 10 flows during transport through the treatment chamber 20 from opposite sides with cooling medium. As a result, the cooling behavior is made uniform.

The arrangement of an air outlet 27 between the first and second sections 31 and 32 of the conveyor 30 allows a good flow of product pallets arranged on the pallets 11.

In the FIG. 1 illustrated basic unit A with an introducer sluice 23, a discharge lock 24 and a reversing position 33 and a return section 34 having conveyor 30 may be supplemented by further units B and C, as shown in FIG. 2 is shown by way of example. Each of the further units B and C in turn comprises a conveyor 30 which has at least one reversing position with a transfer device 35B, 35C for transferring articles from the first section 31B, 31C to the second section 32B, 32C. In modification of the representation of FIG. 2 If appropriate, a return section may additionally be provided on the further units, which may permit a transfer from the second section 32B, 32C to the first section 31B, 31C. Alternatively, with the exception of the last one, that is, the furthest from the introducer sheath 23, all transposing devices 35A, 35B may be bidirectional, that is, allowing hopping between the first and second sections 31A, 31B and 32A, 32B , As a result, 10 different delivery paths within the cooling tunnel 1 can be realized for different items, for example to realize variable target cooling times at high throughput rates or to perform different cooling processes. For this purpose, the onflow regions 22A, 22B, 22C can be operated and / or controlled individually at the treatment positions of the units A, B and C. Bulkheads 28 between the individual units A, B and C permit individual operation in the correspondingly formed chambers or treatment rooms of the units, including a temporary shutdown of one or both further chambers B and C.

In FIG. 2 a total of three units A, B and C are shown. However, their number can be chosen larger or smaller. In particular, the other units B and C can be constructed in the same way. By adding further units, the maximum flow rate of the cooling tunnel 1 can be increased. Optionally, a base unit A with an introducer sluice 23 and a discharge sluice 24 can also be provided at both ends of the cooling tunnel 1.

FIG. 3 shows a view of the conveyor 30 in a plan view, wherein here for the sake of illustration, only a base unit A and another unit B are shown. The first section 31 of the conveyor is divided according to the division of the cooling tunnel 1 in the units A and B in separately drivable portions 31A and 31B. For each treatment position 21.1 to 21.x, the partial area 31A has an individually activatable single-user drive 36.1 to 36.x, so that the objects 10 can be transported individually forward in a region directly adjoining the introducer sheath 23 and the return section 34. In contrast, a chain conveyor with a central drive 37 is provided in the partial area 31B. Also in the subregions 32A and 32B, a chain conveyor with a central drive 38 or 39 is used in each case. Alternatively, it is also possible for a chain conveyor with a central drive to be provided in the partial area 31A instead of the single-space drives 36.1 to 36.x, as in the other partial areas.

FIG. 4 shows a section through the cooling tunnel 1 transverse to the transport direction of the first and second sections 31 and 32 for illustrating the provision and circulation of the cooling medium. As already mentioned above, the cooling medium is provided via lateral onflow regions 22. The pressure supply can be centralized or decentralized. Each unit A, B and C preferably has its own pressure supply device 40. However, in a simplified embodiment, a single pressure supply device 40 may be provided with a central pressure generator for all units A, B and C.

Each pressure supply device 40 comprises one or more fans 41, via which or the air is sucked out of the treatment space 20 and conducted via one or more coolers 42 into pressure chambers 43. The pressure chambers 43 each supply a plurality of treatment positions 21.1. to 21.x via nozzle plates 44 with a defined air flow for cooling the objects located there 10. As in FIG. 4 can be seen, there are two pressure chambers 43 with respective nozzle plates 44 each outside the sections 31 and 32 of the conveyor. Spent cooling air is drawn up between sections 31 and 32. A deduction down is also possible.

By means of the above-described cooling tunnel 1, articles 10 can be processed with greatly different desired cooling times, wherein a high throughput is achieved due to the high system flexibility, while deviations from the target cooling times remain low. In particular, it can be avoided with the above-described cooling tunnel 1 that objects 10 with high set cooling times reduce the throughput of objects 10 with low set cooling times, when both are to be cooled at least with the set cooling time.

The cooling tunnel 1 can be operated fully automatically by means of a control device, wherein objects 10 with different desired cooling times can be introduced into the treatment space 20 via the introduction sluice 23 in any order and at any desired time.

On the one hand, the control device makes possible an individual control of the individual sections 31, 32, 34 and 35 of the conveyor 30 as well as possibly existing section sections 31A, 31B, 31C, 32A, 32B and 32C.

Furthermore, it is configured such that a time account for the required target cooling time is allocated to each object introduced. By means of a decision logic stored in the control device, the feed of the supplied articles 10 is adjusted to one another by activation of the individual sections of the conveyor in order to realize the desired set cooling times while avoiding noticeable excesses. If it is determined in the controller for an item 10 that its cooling time account expires, then the position of the item 10 is determined based on the cooling time account and the intermediate actuation of the conveyor 30 and transported by actuation of the relevant sections of the conveyor 30 in the direction of the discharge lock 24 ,

In this case, it may happen that the article 10 in question is preceded by further articles 10 having a higher residual cooling time. To a premature To avoid rejection of the same, it is checked on detection of an object 10 before the return section 34, if its cooling time account has expired. If this is the case, the object in question 10 is discharged by actuation of the second section 32. Otherwise, the object 10 in question is transferred to the first section 31 of the conveyor 30 by actuation of the return section 34, so that it can be further cooled.

In a multi-turn position configuration 33 as shown in FIGS Figures 2 and 3 2, the actuation of transducers 35 located there is included in the control such that, for example, upon detection of an object 10 before or at such decision logic by means of a decision logic stored in the control device, it is checked whether the object 10 transfers to the second section 32 or stay in the first section 31. By operating a transfer device 35, which is not the furthest from the introducer 23 transfer device 35C, the delivery path for an object 10 can be abbreviated individually. As a result, for example, objects with higher residual cooling times can be overtaken, so that for these the delivery route remains short and unnecessary circulation is not caused.

Based on FIG. 5 By way of example only, a possible process sequence for operating a cooling tunnel 1 or a pallet cooling system with a circulation conveyor 30 passing through successive treatment positions and an introducer sluice 23 and a discharge sluice 24 is to be represented. The positions of the individual objects 10.1 to 10.4 are in FIG. 5 shown for different times t, where on each item the remaining remaining cooling time is given in hours.

At the time t = 0 h there are four objects 10.1 to 10.4 with different remaining cooling times in a pent-up arrangement in the region of the first section 31 adjoining the introducer sheath 23.

At the time t = 0.9 h, it is determined that for the objects 10.2 and 10.4, the target cooling time expires shortly, they should thus be discharged. The control device causes actuation of the relevant sections 31, 35 and 32 in order to transport the objects mentioned in the direction of the discharge lock 24. In this case, the object 10.1 can remain at its treatment position. However, the object 10.3 must be transported in each case so that the subsequent object 10.2 with a shorter residual cooling time does not remain unnecessarily long in the cooling tunnel 1. If a chain conveyor is used in section 31 instead of single-station conveyors, the object 10.1 is taken along at least up to the reversing position 33. Of course, you can also transport all objects 10.1 to 10.4 as a block to the return section 34.

Before reaching the discharge lock 24 is checked before the return section 34 on the basis of the cooling time account for each transported object 10.2, 10.3 and 10.4, whether the target cooling time has been reached. At time t = 1 h, this is the case for object 10.4, so that it is ejected. The next item 10.3 has at this time a remaining cooling time of three hours, so that it is transferred by means of the return section 34 to the first section 31. If necessary, the article 10.1 located there must continue to be advanced for this purpose. The further article 10.2, whose target cooling time has been reached, is likewise discharged at time t = 1 h.

Thus, at time t = 1.1 h, only the objects 10.3 and 10.1 with the remaining cooling times 1.9 h and 2.9 h are in the first section 31. If no new objects are supplied, the feed device 30 is not advanced again, when the remaining items 10.3 and 10.1 are to be flown or discharged from the opposite side.

The above-described cooling tunnel allows for variable target cooling times and compliance with the same within a narrow tolerance range high throughput. The existing conflict of interest in the prior art is thus removed.

The invention has been explained above with reference to an exemplary embodiment. However, it is not limited thereto, but includes all the embodiments defined by the claims.

Claims (15)

1. Cooling tunnel, comprising:

   - a treatment room (20) separated from the exterior,

   - an infeed port (23) for feeding objects to be cooled into the treatment room (20),

   - a discharge port (24) for discharging objects from the treatment room (20),

   - a plurality of successive treatment stations (21.1 to 21.x) within the treatment room (20) for subjecting the objects to be cooled with a cooling medium, especially cooling air, and

   - a conveyor device (30) for transporting the objects to be cooled from the infeed port (23) to the discharge port (24), the conveyor device (30) extending through the individual treatment stations (21.1 to 21.x) and having a first section (31) comprising several treatment stations, which extends from the infeed port (23) to a turnaround station (33), and a second section (32) comprising several treatment stations, which extends from the turnaround station (33) to the discharge port (24),

   characterised in that
   the conveyor device (30) has a return section (34), which is located within the treatment room (20) in front of the discharge port (24) and connects a discharge-side zone of the second section (32) with an infeed-side zone of the first section (31), to selectively discharge objects or to cool them further.
2. Cooling tunnel according to claim 1, characterised in that the first and second section (31, 32) of the conveyor device (30) are arrange alongside each other in said common treatment room (20) and discharge zones (22) for feeding cooling medium to the individual treatment stations (21.1 to 21.x) are arranged on opposite side walls (25, 26) of the treatment room (20)
3. Cooling tunnel according to claim 1 or 2, characterised in that an air exhaust (27) is arranged between the first and second section (31, 32) of the conveyor device (30).
4. Cooling tunnel according to one of claims 1 to 3, characterised in that at the turnaround station (33) a transfer device (35) is arranged for transferring objects from the first section (31) of the conveyor device to the second section (32) of the conveyor device.
5. Cooling tunnel according to claim 4, characterised in that the first section and the second section (31, 32) of the conveyor device have separately drivable sub-zones (31A, 31B, 31C, 32A, 32B, 32C) and at the end of every sub-zone of the first section (31) a transfer device (35A, 35B, 35C) is provided for transferring objects to the second section (32).
6. Cooling tunnel according to claim 5, characterised in that separately controllable outflow zones are assigned to the sub-zones (31A, 31B, 32A, 32B) for feeding cooling medium.
7. Cooling tunnel according to claim 5 or 6, characterised in that the sub-zones (31A, 31B, 32A, 32B) are located in separate treatment rooms, which are separated from one another by bulkhead walls (28).
8. Cooling tunnel according to one of claims 1 to 7, characterised in that the first section (31) of the conveyor device (30) has an individually controllable single-station drive (36) in at least one sub-zone bordering the infeed port for every treatment station.
9. Cooling tunnel according to one of claims 1 to 8, characterised in that a control device is provided for controlling the individual sections of the conveyor device (30) as well as any sub-zones of the sections that may exist, which is configured in such a manner that a time account for the required desired cooling time is assigned to every introduced object, the position of the object can be determined depending on the cooling time account and the actuation of the conveyor device (30), upon detection of an object in front of the return section (34) a check is carried out whether the cooling time account has run out, if that is the case, the relevant object can be discharged by actuating the second section (32), if that is not the case, the object can be transferred to the first section (31) of the conveyor device by actuating the return section (34).
10. Cooling tunnel according to claim 9, characterised in that the dwell times for different feed directions of cooling medium are recorded in the cooling time account.
11. Cooling tunnel according to one of claims 1 to 10, characterised in that the control device is configured in such a way that in case of the presence of several turnaround stations (33), upon detection of an object in front of or at such a turnaround station, a decision logic stored in the control device is used to check whether the object is to be transferred to the second section (32) or is to remain in the first section (31).
12. Method for operating a cooling tunnel with a circulation conveyor device (30) running through successive treatment stations (21.1 to 21.x), as well as an infeed port (23) and a discharge port (24), wherein objects with different desired cooling times are transferred via the infeed port (23) to the circulation conveyor device (30),
    characterised in that
    every object is assigned a time account with a desired cooling time, in which the accumulated dwell time in the cooling tunnel is recorded, and at a position in front of the discharge port (24) it is decided on the basis of the cooling time account whether an object is discharged via the discharge port (24) or remains on the circulation conveyor device (30).
13. Method according to claim 12, characterised in that the dwell times for different feed directions of cooling medium are recorded in the cooling time account.
14. Method according to claim 12 or 13 for a cooling tunnel (1), in which the circulation conveyor device (30) has at least one branch for shortening the transportation path, characterised in that on the basis of the cooling time accounts of several objects it is decided whether an object passes through the short-cut branch or not.
15. Method according to one of claims 12 to 14, characterised in that the objects are banked up a first section (31) of the conveyor device (30).

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