EP2799352B1 - Method for transferring a shrinking tunnel to a production mode and method for transferring a shrinking tunnel from a production mode to a standstill mode - Google Patents

Description

The present invention relates to methods of operating a shrink tunnel according to claim 1. More particularly, the invention relates to a method of transferring a shrink tunnel to a production mode.

In filling and packaging plants, it is known that objects, in particular bottles, cans, beverage cartons or the like, are wrapped by means of a film and subsequently transported through a shrink tunnel. In the case of the objects wrapped in foil, the beverage industry prefers to speak of so-called containers. The film is in this case a heat-shrinkable film, the expert also familiar as LDPE, LLDPE - plastic film. The objects wrapped with such a film are thus transported after their wrapping in a packaging machine through a shrink tunnel and there acted upon with hot air, so that the film shrinks and applies to the objects. A cooling section with fans immediately adjacent to the shrink tunnel ensures rapid cooling of the containers, which gives them their transportable strength.

Such a shrink tunnel now consists essentially of a circulating endless conveyor, which is covered over a section with an enclosure (tunnel), which forms the tunnel. Furthermore, a shrink tunnel usually consists of several heating elements and fans or blowers to produce the required hot air and then distribute in the tunnel interior. In order to achieve a particularly uniform distribution of the hot air, the hot air is passed after their production by means of suitable hot air ducts partly in so-called shaft walls and partly in a chamber which is located directly below the conveying means of the shrinking tunnel. Thus, the containers are preferably actively acted upon by hot air from at least three sides. The basic structure of a shrink tunnel is explained here only in rough breaks. A person skilled in the packaging industry knows enough about the structure of such shrink tunnels, so that no further details have to be mentioned here at this point.

As already mentioned, such a shrink tunnel for shrinking the film requires a hot gaseous medium, usually hot air. This hot air is through the Heating means which are part of a shrink tunnel generated. The hot air generated or the hot air generated by the heating means is preferably generated with electrical energy. Meanwhile, it has also gone over to produce the required hot air by means of, for example, a so-called gas burner. Unfortunately, the required gas is not readily available in many places, which is why electrically heated shrink tunnels are then used again.

Such electrically heated shrink tunnels have a high demand for electrical energy, resulting in not inconsiderable costs for the operator. In particular, the generation of hot air turns out to be the largest energy consumers in a shrink tunnel. Now it has been found that the consumption of electrical energy can be reduced in a shrink tunnel, in which one of the shrink tunnel for the operating conditions or operating modes Production is required, this put into a so-called stand-by mode. In this case, one or more consumers of the shrinking tunnel are reduced in their performance and thus reduced energy consumption compared to the production operation.

Such a shrink tunnel or such a method for operating a shrink tunnel, for example, from the DE102010011640 A1 out. Here, a shrink tunnel is described, which in addition to the conventional production mode has a further so-called stand-by mode, by means of this stand-by mode of the shrink tunnel is operated with respect to the production mode reduced power. The change between the conventional production mode and the further stand-by mode is time-controlled and / or signal-controlled. When switching to the stand-by mode, some measures are taken which lead to a reduction in the energy requirement of the shrink tunnel. One measure would be, for example, that the existing target temperature is adjustable to a relation to the target temperature reduced standby temperature, with the result that less heating power is required. Another measure would be, for example, reducing the transport speed of the shrink tunnel side transporter in order to minimize the energy discharge, respectively the heat emission, from the tunnel. Again, it is clear that the shutdown of cooling the shrinking tunnel side transporter and also the cooling of the containers, which drive out of the shrink tunnel, would be measures to reduce the energy requirement. The shutdown of a fan of the heating means per tunnel zone, if each tunnel zone at least two electrically operated blower are assigned, causes a reduced energy demand.

Furthermore, it is known that the so-called stand-by mode brings with it a further measure, wherein the two openings in the entrance and exit areas of the shrink tunnel are at least partially closed. The shrink tunnel entrance area and the shrink tunnel exit area are logically opened so far in a conventional production mode that the packages can enter and exit unhindered into the shrink tunnel. The shrink tunnel entrance area and the shrink tunnel exit area are either opened or closed during a change between the respective operating modes, ie between the production mode and the stand-by mode. The change between the two operating modes is also triggered by time and / or signal. Such a control for operating a shrink tunnel and such a shrink tunnel itself go for example from the DE 102010020957 A1 out.

The above-cited prior art thus already discloses a shrink tunnel or a method for controlling a shrink tunnel which changes over time and / or signal-controlled between two operating modes in which a different energy requirement is obtained in each case. Furthermore, the document discloses a shrink tunnel or a method for controlling a shrink tunnel, which additionally opens or closes the shrink tunnel openings in the entrance and exit areas of the shrink tunnel when switching between two modes of operation.

The object of the present invention is now to optimize the cited prior art in such a way that the energy requirement of the shrink tunnel during startup or switching on of the shrink tunnel is further optimized and in particular minimized.

The object is achieved by a method for transferring a shrink tunnel into a production mode according to claim 1.

It has been shown that, after the time-controlled and / or signal-controlled change between the individual operating modes known from the prior art, a defined sequence of steps of individual measures mentioned above for the operation or control of a shrink tunnel leads to the result that the energy requirement follows immediately the change up to reaching the specifications of the respective operating modes can be further reduced.

Thus, the invention shows a method for transferring a shrink tunnel with a conveyor into a production mode, which and the like. opening one of a shrink tunnel entrance area and / or opening a shrink tunnel exit area. This method may in particular relate to a first commissioning of a shrink tunnel or the transfer of a shrink tunnel from a stand-by mode to a production mode. Furthermore, a shrink tunnel, in which due to a longer downtime all energy consumers have been turned off, and thus is in a so-called stop mode, be transferred to the production mode. The essential difference between the stand-by mode and the stop mode is that the shrink tunnel in stand-by mode, as known in the art, is maintained at a lower second target temperature. By switching off all energy consumers in the stop mode, the interior of the shrink tunnel can cool down to the ambient temperature depending on the duration of the downtime. If the shrink tunnel is to be brought back into production mode, then the actual tunnel temperature is not known.

The method further comprises the following step: switching on the conveying means of the shrinking tunnel or increasing the speed of the conveying means of the shrinking tunnel to a predetermined desired value.

Another special feature of the method according to the invention provides that the step of switching on the conveyor or increasing the speed of the conveyor in response to the progress of the heating of the shrink tunnel to a predefined setpoint temperature.

The step of switching on the conveyor or increasing the speed of the conveyor takes place in dependence on the progress of the heating of the shrinking tunnel to a predefined setpoint temperature. For example, it may be provided to switch on the conveying means only when the temperature in the interior of the shrinking tunnel has reached approximately 90% of the nominal value. The conveyor also requires a certain setpoint temperature for the production mode. If the conveyor is too cold, this negatively affects the quality of the shrinkage result in the bottom area of the containers. If the conveyor is switched off in the stand-by mode, then essentially only the transport area within the shrink tunnel heats up during heating of the shrink tunnel interior. The return area of the conveyor, however, remains cold depending on the arrangement. The time at which the conveyor is turned on or to which the speed of the conveyor is increased, is chosen so that the Passing through the shrink tunnel during the time required to heat the shrink tunnel to the final set point of the required shrink tunnel interior temperature, all areas of the conveyor are sufficiently heated so that it is heated to the required production temperature.

Furthermore, it is provided according to the inventive method that the opening of the shrink tunnel entrance area and / or the opening of the shrink tunnel exit area takes place upon reaching the defined target value of the shrink tunnel interior temperature.

The method includes at least the steps of increasing the shrink tunnel interior temperature to a predefined set point; and switching on the conveyor or increasing the speed of the conveyor to a predetermined setpoint. Furthermore, the method may comprise at least one of the steps described below: increasing the chain cooling capacity for cooling the conveyor to a predetermined desired value; and / or increasing the container cooling capacity to a predetermined desired value.

At this point, the details of the components of a shrink tunnel required for the process according to the invention should again be discussed in detail, which in the later course are essential for the processes according to the invention.

A shrink tunnel according to the invention for the inventive method consists of the components described at least below. Such a shrink tunnel has an electric motor-driven conveying means and one or more aggregates also acting in combination (eg hot air blower in the form of fans, heating registers, sensors), which are responsible for the necessary generation of hot air and thus for setting the shrink tunnel interior temperature, respectively for achieving a predefined setpoint value. eg temperature in ° C, are necessary. In particular, sensors may be provided in the interior of the shrink tunnel, which determine the actual temperature and pass the value to a control unit. The actual temperature is compared with the target temperature and the hot air blower and / or heater are then readjusted so that the target temperature is set in the interior of the shrink tunnel. Furthermore, a shrink tunnel according to the invention used for the method according to the invention has a so-called electric chain cooling, which consists for example of one or more aggregates acting in combination such as fans and possibly sensors, which are arranged outside the tunnel interior, preferably below the revolving conveyor. The cooling units serve the Cooling of the conveyor, which is eg a mesh grid belt or a so-called Stabröllchenkette. The conveyor heats up when passing through the shrink tunnel. Before it passes through the shrink tunnel again, it must be cooled down during the return, otherwise there is a risk that the packaging material and / or the subsequently promoted items at least partially melt and stick to the conveyor. Furthermore, a shrink tunnel according to the invention used for the method according to the invention has at least one or more aggregates acting in combination, such as axial fans or cross-flow fans, which are usually arranged immediately after the shrink tunnel interior, ie outside and above and / or laterally of the conveyor, which are needed for the cooling of the containers and thus for the necessary cooling capacity. Furthermore, it is provided for the method according to the invention that in the region of the two tunnel openings of the shrink tunnel according to the invention doors or other suitable closure elements are arranged, which automatically close or open when needed, which reduces heat leakage from the shrink tunnel in a closed state of the doors or closure elements becomes. In order to operate all the named consumers in a defined manner, in particular in a defined sequence of steps, the shrink tunnel further comprises a separate control by means of which the methods according to the invention can be carried out. In this control, the data necessary for the inventive method are stored. Preferably, the shrink tunnel required for the inventive method is still equipped with at least one sensor (eg light barrier) on the inlet side of the tunnel and at least one other sensor (eg light barrier) on the outlet side of the tunnel. Furthermore, it is important for the method according to the invention that the own control unit of the shrinking tunnel has an interface to a packaging machine or control unit of the packaging machine which precedes the shrinking tunnel and that these can mutually communicate with one another. The communication interface for communicating the shrink tunnel with the upstream packaging machine can be done for example via a so-called Ethernet network.

Since individual measures or steps, which are necessary for the operation according to the invention of a shrink tunnel, on the one hand require a different energy demand and on the other hand depending on certain parameters different time, it is advantageous to bring these individual measures or steps in a defined order.

Through a defined sequence of individual steps, it is possible to further reduce the energy requirement during certain measures. Starting from a production mode and a stand-by mode, each of the two operating modes thus has to first go through a few steps, which in turn are defined setpoints as default to reason. In order to achieve these target values, the initiation of specific measures or steps thus takes place with each change from one operating mode to another operating mode. It has been found that if the individual steps or measures are carried out in a defined sequence, the defined energy demand during execution of one or more steps can be reduced even further.

In the method according to the invention, therefore, it is primarily decisive when a single or several steps are carried out and also how long the duration of a step or several steps is in order to carry it out completely.

In the following, further embodiments or further developments will be described. Furthermore, the method according to the invention may also comprise at least one further step: increasing the chain cooling capacity to a predetermined desired value and / or increasing the unit cooling capacity to a predetermined desired value.

A further variant of the method according to the invention proposes that the opening of the shrink tunnel entrance area and / or the opening of the shrink tunnel exit area takes place at the same time as or at the latest after one of the steps mentioned above.

Thus, it is particularly advantageous to use a method for operating a shrink tunnel, wherein the opening of a shrink tunnel entrance area and / or the opening of a shrink tunnel exit area at the earliest takes place when the shrink tunnel interior temperature reaches the predetermined target value. It is thus prevented that during the heating process of the shrink tunnel interior, which by means of several electrical, energy consuming, individually or in combination acting aggregates, the shrink tunnel entrance area and / or the shrink tunnel exit area are opened prematurely. The necessary for the heating unit units such as heater, fan heater, blower can thus be operated as efficiently as possible, since the shrink tunnel entrance area and / or the shrink tunnel exit area are in a closed state. If both shrinkage tunnel inlet and outlet areas are closed during the heating process, this also shortens the duration of the heating process, in particular shortened the duration of the step of increasing the shrink tunnel interior temperature to the predetermined set point. The earliest opening of the shrink tunnel entrance area and / or shrink tunnel exit area when the predefined setpoint value of the shrink tunnel interior temperature step is reached, reduces the heating time and further minimizes heat loss, thereby reducing the resulting energy demand for the step. Furthermore, with the earliest opening of the shrinking tunnel entrance area and the shrinking tunnel exit area, which occurs only when the target value of the step of increasing the shrink tunnel interior temperature is reached, due to the shortened heating period, the provisioning time of a required state of the shrinking tunnel for the production is shortened.

In a further particular embodiment, the steps of "opening the shrink tunnel entrance area and / or opening the shrink tunnel exit area" are made to a predefined set point depending on the progress of the step of increasing the shrink tunnel interior temperature. Thus, to prevent backwash heat buildup in the shrink tunnel interior just prior to reaching the predefined shrink tunnel interior temperature set point, the shrink tunnel entry area opening and / or shrink tunnel exit area opening may already occur when a predefined temperature is reached that is below the production mode set point. This avoids potential build-up of heat build-up within the shrink tunnel, which can cause the first packages transported through the shrink tunnel to overheat. In other words, due to the opening of the shrink tunnel entrance area and / or the opening of the shrink tunnel exit area upon reaching a defined target temperature which corresponds, for example, to 90-95% of the predefined set value of the shrink tunnel interior temperature, a build-up of heat build-up within the shrink tunnel can be avoided, whereby the first After completion of step a) Increase the shrink tunnel interior temperature to a predefined set point, containers carried therethrough will not experience overheating or damage. This causes an improvement in the quality of the first processed in the shrink tunnel containers that would otherwise have to be discarded if necessary.

At the same time, it may be necessary to switch on the chain coolant or to increase the chain cooling power so that the temperature of the conveyor, in particular in the shrink tunnel entrance area, has the desired temperature.

A further particular embodiment of the method according to the invention therefore provides that the increase in the chain cooling power takes place to a predefined desired value as a function of a determined chain temperature. In a shrink tunnel, the conveyor, e.g. Mesh mesh link chain, rod roll chain, continuously cooled in a normal production mode to prevent it from overheating. Too much heated conveyor would result in melting of packaging material and possibly also partial melting of the articles. This leads to contamination of the conveyor with plastic residues and hinders further transport. In addition, this can lead to severe loss of quality in the shrunk-ready container. Now, the method according to the invention provides that, in addition to the opening of the shrink tunnel entrance area and / or opening of the shrink tunnel exit area during the increase of the cooling capacity for cooling the conveyor, an increase of the chain cooling capacity occurs as a function of a determined conveyor temperature. By increasing the cooling capacity as a function of the determined temperature of the conveyor this is only increased, if it is really necessary. Thus, targeted and efficient energy consumption can be further reduced. The temperature of the conveyor is determined in particular in or subsequent to the shrink tunnel exit area by a sensory measurement of the temperature and adjusted with a predefined setpoint. This setpoint corresponds to a temperature value that the conveyor should have in the shrink tunnel input area. When the conveyor is returned between the shrink tunnel exit area and the shrink tunnel entrance area, an adapted cooling of the conveyor takes place. The success of the cooling can be checked by means of a second temperature sensor arranged in the return area and, if appropriate, the chain cooling power can then be adjusted again.

It has also been found that it may be useful if the shrink tunnel doors or closure elements are opened not only as a function of the shrink tunnel interior temperature, but also as a function of the containers, which are produced by the upstream packaging machine and transported through the conveyor through the shrink tunnel. It can therefore also here a loss of energy due to a premature opening of the shrink tunnel doors or closure elements can be avoided. For example, at the start of the packaging machine the time can be used, which requires the packaging machine to wrap a first container with foil, which is passed after the shrink tunnel. This time is not insignificant. Due to the restart of the packaging machine and the first steps to be performed such as dividing individual items into one Barrel formation, further transporting the package formation into a film wrapping module, wrapping the package formation with shrinkable film, removal of the wrapped film packs and transfer to the conveyor, takes some time until the shrink tunnel is needed for its conventional production task, the shrinking of containers. Thus, it would be conceivable that the shrink tunnel entrance area is opened only when the packaging machine has already begun with the production of the film pack and its wrapping. Particularly preferably, the shrink tunnel entrance area opens only with the completion of a first wrapped with shrink wrap. The shrink tunnel exit area can either be opened under the same conditions, or until a certain time has elapsed, if before, depending on the speed of the conveyor. On the basis of the completion of the wrapped Foliengebindes and its transfer to the funding and on the basis of the known conveying speed of the conveyor can be determined very accurately how long the transport of the first container needed to arrive at the shrink tunnel exit area. The shrink tunnel exit area is thus opened in good time before the container reaches it.

Another particular way that makes the control of the shrink tunnel doors even more efficient and requires less complicated programming operations would be that the shrink tunnel entrance area and the shrink tunnel exit area each have their own sensors. An embodiment of the sensor system provides a first light barrier at least in front of the shrink tunnel entrance area. Depending on occupancy and a predetermined time interval, this light barrier arrangement controls the opening time of the two shrink tunnel doors, wherein the shrink tunnel entrance area is opened first and the shrink tunnel exit area only after a subsequent predetermined time interval. Alternatively, the shrink tunnel exit area may also be opened simultaneously with the opening of the shrink tunnel entrance area. This type of opening control of the two shrink tunnel doors or closure elements appears to be particularly preferred and at the same time as the simplest and most direct way to open the shrink tunnel doors or closure elements, if necessary, i. especially if the containers enter the shrink tunnel or are located shortly before the shrink tunnel entrance area or if the containers are located in the shrink tunnel just before the shrink tunnel exit area.

It should be noted in passing that this way of controlling the shrink tunnel doors via a photoelectric barrier assembly is also used to close the shrink tunnel entrance area and the shrink tunnel exit area as directly and quickly as possible. For this purpose, it can be provided that in each case a light barrier is arranged in front of the shrink tunnel entrance area and immediately after the shrink tunnel exit area.

Furthermore, in the reactivation measure in which the shrink tunnel is approached completely or raised from a standby mode in the production mode, the conveyor before or when transferring the first container on the conveyor are operated for a short time with an increased transport speed. This additional process step contributes only indirectly to the optimization of the energy requirement or energy consumption. When reactivating and opening the tunnel doors only at or shortly before reaching the required target operating temperature in the interior of the shrink tunnel, formed by the previously closed doors so-called heat accumulation in the shrink tunnel. If the first containers are moved into the shrink tunnel immediately after opening the doors, these containers are subject to the aforementioned accumulation heat. This can lead to the first containers entering the shrink tunnel possibly being exposed to too much heat energy. For this reason, after the shrinking doors are opened late, the transport speed of the conveyor may need to be temporarily above the normal transport speed required for normal production operation. Thus, in proportion, due to the short-term increase in the transport speed, the same heat energy acts on the first continuous drums as on the succeeding drums, which are conveyed through the shrink tunnel under normal production conditions at normal transport speed. To clarify here which are the first containers, which are transported through the shrink tunnel with increased transport speed and which are the following containers that are driven through the shrink tunnel under the normal production conditions, it should be noted at this point that the first container a number of at least five containers, but not more than 25 containers. If you were to transport even more containers with an increased transport speed through the shrink tunnel, so would be due to the lack of heat storage optimal shrinkage result is no longer guaranteed. The short-term increase in the transport speed can be defined in terms of time with about one to three minutes.

As already described, the shrink tunnel can be in a stop mode in which all energy consumers are completely switched off. Or the shrink tunnel is in a stand-by mode in which the power of the power consumers is at least partially reduced. A part of the energy consumers, for example a part of the heating means can also be completely switched off. In essence, the shrink tunnel from standby mode can be relatively quickly put back into production mode. In the stop mode, on the other hand, all energy consumers are switched off so that the shrink tunnel can even cool to room temperature depending on the duration of the downtime. In particular, the stop mode of the shrink tunnel is initiated by putting the control unit in a stop mode, thereby causing shutdown of all energy consumers. In order to put the shrink tunnel back into production mode, it can therefore be provided in a further method step that the control unit and thus the shrink tunnel are first woken up from the stop mode and transferred into a so-called run mode in which, for example, all heating means of the Shrink tunnels are operated at maximum power. If then a shrink tunnel interior temperature is reached, which corresponds approximately to the target internal temperature in the stand-by mode or about 85-90% of the target internal temperature in stand-by mode, the power of the heating medium is reduced again and the process steps for transferring the Shrink tunnels from stand-by mode into production mode are initiated.

Furthermore, a method for transferring a shrink tunnel into a production mode is described, wherein the method comprises at least opening a shrink tunnel entrance area and / or opening a shrink tunnel exit area. It is provided that the shrink tunnel entrance area and / or the shrink tunnel exit area of the shrink tunnel are initially closed. First, the shrink tunnel is put in an operating mode. This is done by switching on or boosting the power of at least one consumer within the shrink tunnel. The opening of the shrink tunnel entrance area and / or the opening of the shrink tunnel exit area occurs at the earliest with the switching on or increasing the power of the at least one consumer within the shrink tunnel. In particular, it is provided that the opening of the shrink tunnel entrance area and / or the opening of the shrink tunnel exit area only takes place when a minimum temperature in the interior of the shrink tunnel has been reached. This is controlled and controlled, for example, via a temperature sensor coupled to a control unit. Subsequently, the performance of other consumers is increased to the production output, which sets the production mode of the shrink tunnel.

Furthermore, a method for transferring a shrink tunnel from a production mode to a standstill mode will be described. Standstill mode can be understood as a standby mode in which the shrink tunnel is operated at a reduced power. Standstill mode can also be understood as a stop mode in which all energy consumers of the shrinking tunnel are completely switched off. The method includes at least closing a shrink tunnel entrance area and / or closing a shrink tunnel exit area. Furthermore, the method comprises at least one of the following steps: lowering the shrink tunnel interior temperature to a predefined setpoint value; Reducing the speed of the conveyor to a predetermined setpoint; Reducing the chain cooling capacity to a predetermined target value; Reduce the package cooling capacity to a specified setpoint. According to the invention, it is provided that the closing of the shrink tunnel entrance area and / or the closing of the shrink tunnel exit area takes place at the latest with one of the aforementioned method steps.

Furthermore, provision may be made for closing the shrink tunnel entrance area and / or closing the shrink tunnel exit area prior to one of the aforementioned method steps. Particularly preferably, the closing of the shrink tunnel entrance area and / or the closing of the shrink tunnel exit area takes place as a first step before one of the aforementioned method steps. In particular, the aforementioned method steps can be performed in any order or at the same time.

According to one embodiment, reducing the speed of the conveyor takes place at the latest with the lowering of the shrink tunnel interior temperature. Due to the constant movement of the conveying means, when the shrinking tunnel is being heated, it is always ensured that heat is not continuously supplied to the conveying means. In particular in the return area there is no supply of heat, so that the conveying means can always cool down in regions. Would the transport speed of the conveyor already lowered before lowering the temperature in the interior of the shrink tunnel or the funding be stopped completely, it could be locally in the interior of the shrink tunnel to a strong overheating of the funding, which also causes damage to the funding or other components within could cause the shrinking tunnel. For this reason, as already described, the conveying medium generally also has to be cooled in normal production operation in order to prevent overheating of the product Conveying and thus caused damage to the processed containers to avoid.

According to one embodiment, reducing the chain cooling performance takes place at the latest with the reduction of the speed of the conveyor. In combination with the above, it follows that preferably the lowering of the shrink tunnel interior temperature, the reduction of the transport speed of the conveyor and the reduction of the chain cooling capacity take place at the same time.

The method may further include an additional step of determining the position of the packages carried on the conveyor and closing the shrink tunnel entrance area and / or the shrink tunnel exit area depending on the detected position.

When the method for transferring a shrinking tunnel from a production mode to a standstill mode is to be performed, the shrink tunnel is no longer supplied with packages to be processed. However, no containers should remain in the shrink tunnel during standstill mode. Thus, the shrink tunnel entrance area could already be closed after the last container is retracted into the shrink tunnel, while the shrink tunnel exit area can not be closed until the last container has left the shrink tunnel. However, since in this case could accumulate heat, both areas are preferably closed at the same time, after all containers have left the shrink tunnel.

According to a further embodiment, it can also be provided for foreseeable longer downtimes that the setpoint values of the abovementioned method steps are equal to zero. In particular, it is provided in a so-called stop mode that all energy consumers of the shrinking tunnel are switched off. In this case, there is no monitoring of the shrink tunnel interior temperature, so that it can cool down in extreme cases to a temperature which corresponds approximately to the prevailing ambient temperature.

In particular, at the latest after the execution of all the aforementioned method steps, a further step may be provided which sets the control unit of the shrinking tunnel in a stop mode. The execution of all the aforementioned Verfahrensschrff suggest in particular towards a longer downtime and thus serves as a signal for the control unit to turn off all energy consumers completely.

Furthermore, a method for transferring a shrink tunnel from a production mode into a standstill mode is described, wherein the method comprises at least closing a shrink tunnel entrance area and / or closing a shrink tunnel exit area. In the production mode, the shrink tunnel entrance area and the shrink tunnel exit area are at least partially opened to allow passage of the articles or article assemblies through the shrink tunnel entry area into the shrink tunnel and through the shrink tunnel exit area out of the shrink tunnel. The shrink tunnel is first put into an operating mode by turning off or reducing the power of at least one consumer within the shrink tunnel. According to the invention, the closing of the shrink tunnel entrance area and / or the closing of the shrink tunnel exit area occurs at the earliest with the switching off or lowering of the power of the at least one consumer within the shrink tunnel. In particular, it is provided to close the shrink tunnel entrance area and the shrink tunnel exit area at the same time as switching off or reducing the power of the at least one consumer. Thus, the existing heat is largely retained in the interior of the shrink tunnel and this cools less quickly. Subsequently, the shrink tunnel can be set by switching off or reducing the power of other consumers in a standstill mode, in particular in the stand-by mode or even in the stop mode. If the shrink tunnel for a new production now be put back into production mode, this is done for example via the intermediate step of the operating mode. Depending on the given actual temperature in the interior of the shrink tunnel in standstill mode, if necessary, less energy must be applied to reach the operating mode and then the production mode.

• Figur 1 zeigt einen schematischen Überblick über ein Verfahren zum Überführen eines Schrumpftunnels in verschiedene Betriebsmodi.
• Figur 2 zeigt eine bevorzugte Ausführungsform eines Verfahrens zum Überführen eines Schrumpftunnels von einem Produktionsmodus in einen Stand-By Modus und anschließend in einen Stop-Modus.
• Figur 3 zeigt einen schematischen Überblick über ein Verfahren zum Uberführen eines Schrumpftunnels zwischen einem Produktionsmodus und einem Stillstandmodus über einen Zwischen-Betriebsmodus.

In the following, embodiments of the invention and their advantages with reference to the accompanying figures will be explained in more detail.

• FIG. 1 shows a schematic overview of a method for transferring a shrink tunnel in different operating modes.
• FIG. 2 shows a preferred embodiment of a method for transferring a shrink tunnel from a production mode in a stand-by mode and then in a stop mode.
• FIG. 3 shows a schematic overview of a method for transferring a shrink tunnel between a production mode and a standstill mode via an intermediate mode of operation.

For identical or equivalent elements of the invention, identical reference numerals are used. Furthermore, for the sake of clarity, only reference symbols are shown in the individual figures, which are required for the description of the respective figure. The illustrated embodiments are merely examples of how the inventive methods may be configured and are not an exhaustive limitation.

FIG. 1 shows a schematic overview of a method for transferring a shrink tunnel in different operating modes. In the PM production mode, the shrink tunnel largely has a defined internal temperature Ti-PM, which is necessary for normal shrinking operation. This is below the melting temperature of the packaging material and the article. For example, the internal temperature Ti-PM in production mode PM is about 200 ° C. The conveying means, with which the packaging-enveloped articles or article compositions are conveyed through the shrinking tunnel, moves at a predefined production speed V (F) -PM. In particular, the conveyor is a continuously moving endless conveyor. This heats up when passing through the shrink tunnel and is at least partially cooled down again during the return between the shrink tunnel entrance area and the shrink tunnel exit area via first blower or other first coolant supplier. In production mode, the first coolant suppliers operate with a cooling capacity P (F) -PM. Furthermore, after leaving the shrink tunnel, the packages are cooled down by means of second blowers or other second coolant suppliers before being fed to further processing devices. In production mode PM, the second coolant suppliers operate with a cooling capacity P (G) -PM.

• aa) Die Schrumpftunnelinnenraumtemperatur wird auf einen vordefinierten Sollwert Ti-SB abgesenkt, der beispielweise zwischen 50 °C bis 80 °C unterhalb der Schrumpftunnelinnenraumtemperatur Ti-PM im Produktionsmodus liegt.
• bb) Weiterhin wird die Geschwindigkeit des Fördermittels auf einen vorgegebenen Sollwert V(F)-SB reduziert, der unterhalb der Geschwindigkeit V(F)-PM des Fördermittels im Produktionsbetrieb bzw. Produktionsmodus PM liegt.
• cc) Die Kettenkühlleistung wird auf einen vorgegebenen Sollwert P(F)-SB reduziert, der unterhalb der Kettenkühlleistung P(F)-PM im Produktionsbetrieb bzw. Produktionsmodus PM liegt.
• dd) Die Gebindekühlleistung wird auf einen vorgegebenen Sollwert P(G)-SB reduziert, der unterhalb der Gebindekühlleistung P(G)-PM im Produktionsbetrieb bzw. Produktionsmodus PM liegt.

In order to reduce the energy consumption of the shrink tunnel during production or repair-related downtime, the shrink tunnel can be set in a first stand-by mode SB. In particular, the following measures are carried out individually or in any combination:

• aa) The shrink tunnel interior temperature is lowered to a predefined setpoint Ti-SB, which is, for example, between 50 ° C to 80 ° C below the shrink tunnel interior temperature Ti-PM in the production mode.
• bb) Furthermore, the speed of the conveyor is reduced to a predetermined desired value V (F) -SB, which is below the speed V (F) -PM of the conveyor in the production mode or production mode PM.
• cc) The chain cooling capacity is reduced to a predetermined target value P (F) -SB, which is below the chain cooling capacity P (F) -PM in production mode or production mode PM.
• dd) The package cooling capacity is reduced to a predetermined target value P (G) -SB, which is below the package cooling capacity P (G) -PM in production mode or production mode PM.

Furthermore, the shrink tunnel entrance area and the shrink tunnel exit area are closed at the latest with one of the steps aa), bb), cc) or dd) via doors or other suitable closure elements.

Preferably, in a process step ee), the position of the transported on the conveyor container is determined. Closing of the shrink tunnel entrance area and / or the shrink tunnel exit area takes place in dependence on the determined position of the containers. In particular, the shrink tunnel entrance area is closed only when there are no containers in an inlet area to the shrink tunnel. Furthermore, the shrink tunnel exit area is not closed until there are no more containers inside the shrink tunnel.

After the shrink tunnel has reached the stand-by mode SB, the control unit can be put into a stop mode in a method step ff), in particular for longer standstill times. As a result, a complete shutdown of all energy consumers of the shrink tunnel is initiated and the shrink tunnel is placed in a stop mode S. In stop mode S, the desired value of method steps aa) to dd) corresponds in each case to a value equal to zero. In particular, the heating means are switched off, so that the interior of the shrink tunnel cools out in an uncontrolled manner and, depending on the duration of the downtime, largely adapts to the ambient temperature RT. Furthermore, the funding per se and the chain coolant and the container coolant are completely switched off.

1. a) Die Schrumpftunnelinnenraumtemperatur wird auf einen vordefinierten Sollwert der Schrumpftunnelinnenraumtemperatur Ti-PM für den Produktionsmodus PM aufgeheizt.
2. b) Die Geschwindigkeit des Fördermittels wird auf eine Geschwindigkeit V(F)-PM des Fördermittels im Produktionsbetrieb erhöht. Das Einschaltens des Fördermittels bzw. das Erhöhens der Geschwindigkeit des Fördermittels erfolgt in Abhängigkeit des Fortschritts des Aufheizens des Schrumpftunnels auf die vordefinierte Solltemperatur Ti-PM. Der Zeitpunkt, an dem das Fördermittel eingeschaltet bzw. zu dem die Geschwindigkeit des Fördermittels erhöht wird, wird dabei so gewählt, dass beim Durchlaufen des Schrumpftunnels während der Zeit, die benötigt wird, um den Schrumpftunnel auf den endgültigen Sollwert der Schrumpftunnelinnentemperatur Ti-PM aufzuheizen, alle Bereiche des Fördermittels ausreichend erwärmt werden, so dass dieses allumfassend auf die notwendige Produktionstemperatur aufgeheizt wird,

In order to bring the shrink tunnel from stand-by mode SB back into production mode PM, the following measures are carried out:

1. a) The shrink tunnel interior temperature is heated to a predefined set point of the shrink tunnel interior temperature Ti-PM for the production mode PM.
2. b) The speed of the conveyor is increased to a speed V (F) -PM of the conveyor in the production mode. The switching on of the conveyor or increasing the speed of the conveyor takes place in dependence on the progress of the heating of the shrinking tunnel to the predefined setpoint temperature Ti-PM. The time at which the conveyor is switched on or at which the speed of the conveyor is increased, is chosen so that during the passage through the shrink tunnel during the time required to heat the shrink tunnel to the final target value of the shrink tunnel interior temperature Ti-PM , all areas of the conveyor are heated sufficiently, so that this is heated all-encompassing to the necessary production temperature,

• c) Die Kettenkühlleistung wird auf die Kettenkühlleistung P(F)-PM im Produktionsbetrieb erhöht.
• d) Die Gebindekühlleistung wird die Gebindekühlleistung P(G)-PM im Produktionsbetrieb erhöht.

Furthermore, the following method steps can additionally take place:

• c) The chain cooling capacity is increased to the chain cooling capacity P (F) -PM during production.
• d) The package cooling capacity increases the package cooling capacity P (G) -PM during production.

Furthermore, the doors or closure elements in the shrink tunnel entrance area and in the shrink tunnel exit area are opened when the defined target value of the shrink tunnel interior temperature Ti-PM is reached.

To bring the shrink tunnel from the stop mode S back into the production mode PM, there are essentially two options. In the first possibility, the control unit is switched from the stop mode to an activation mode. The energy consumers of the shrink tunnel are at least partially turned on, so that the shrink tunnel in the stand-by mode with a defined shrink tunnel interior temperature Ti-SB, a reduced speed V (F) -SB of the conveyor, a reduced chain cooling power P (F) -SB and / or a reduced container cooling power P (G) -SB is added. Subsequently, the final adaptation of the tunnel power to the production mode PM and the opening of the entrance and / or exit area of the shrink tunnel takes place.

Alternatively, the control unit can be switched from the stop mode to a run mode. This is used to produce the production mode PM of the shrink tunnel within a very short time by operating at least a part of the energy consumers for a short time with increased power. In particular, it can be provided to operate the heating means for a short time with maximum power. The temperature in the interior of the shrink tunnel is monitored by sensors. If the shrink tunnel inner temperature exceeds a defined value, which is set between 85-95% of the shrink tunnel inner temperature Ti-PM in the production mode PM, then the power of the heating means is switched to normal production capacity. The run mode according to a further method step f) on the one hand causes rapid heating of the interior space, on the other hand avoiding overheating of the shrink tunnel interior on the one hand by the timely downregulation.

Preferably, the input and output area are opened only when the necessary shrink tunnel interior temperature is set. Furthermore, it can be provided that the entrance area is opened only when containers to be processed are located in the inlet area to the shrink tunnel. Furthermore, the exit area can only be opened when the first containers are already in the shrink tunnel. In addition, the conveying means can be operated for a short time with an increased transport speed before or upon transfer of the first container to the conveyor. This prevents the quality of the shrink wrap from suffering from heat buildup in the shrink tunnel. By increasing the transport speed in the short term for a period of between one and three minutes, the same heat energy acts on the first continuous drums as on the succeeding drums which are conveyed through the shrink tunnel under normal production conditions at normal transport speed. This is especially necessary if the heating of the shrink tunnel is not monitored by sensors.

According to a particularly preferred and in FIG. 2 In the illustrated embodiment of a method for transferring a shrink tunnel from a production mode PM to a standby mode SB and then into a stop mode S, first the shrink tunnel entrance area and the shrink tunnel exit area are closed. In a subsequent further step, the power of the energy consumers mentioned under aa) to dd) is reduced. This preferably happens largely at the same time. Closing the shrink tunnel, in particular, causes the heat to be largely stored in the shrink tunnel and less energy needed to maintain the stand-by temperature setpoint Ti-SB inside the shrink tunnel. Like in Related to FIG. 1 described, can be effected via the control unit, a complete shutdown of the shrink tunnel and this are set in a stop mode S.

FIG. 3 shows a schematic overview of an embodiment of a method for transferring a shrink tunnel between a production mode PM and a standstill mode, in particular a stand-by mode SB or a stop mode S, via an intermediate mode of operation BM.

In production mode PM, the shrink tunnel entrance area and the shrink tunnel exit area are at least partially opened to allow passage of the articles or article assemblies. At shutdown, the shrink tunnel is first put into an operating mode BM by turning off or reducing the power of a consumer within the shrink tunnel. In this case, the closing of the shrink tunnel entrance area and / or the closing of the shrink tunnel exit area in the illustrated embodiment takes place simultaneously with the switching off or lowering of the power of the one consumer within the shrink tunnel, whereby the existing heat inside the shrink tunnel is largely retained. Thereafter, the shrink tunnel may be shut down or reduced by the power of other consumers according to any of the related art FIGS. 1 and 2 described process steps aa) and / or bb) and / or cc) and / or dd) and / or ee) and / or ff) in a standstill mode, in particular in the stand-by mode SB or even in the stop mode S, be offset.

If the shrink tunnel for a new production is to be put back into the production mode PM from standstill mode SB or S, this is also done via the intermediate step of the operating mode BM. Depending on the given actual temperature in the interior of the shrink tunnel in standstill mode SB or S, less energy may have to be applied in order to reach the operating mode BM and then the production mode PM. The shrink tunnel entrance area and the shrink tunnel exit area of the shrink tunnel are shut off in SB or S standstill mode. First, the power of a consumer within the shrink tunnel is increased by powering up or boosting. The opening of the shrink tunnel entrance area and the opening of the shrink tunnel exit area occurs at the earliest with the switching on or raising of the power of the consumer within the shrink tunnel. According to the illustrated embodiment, the opening of the shrink tunnel entrance area and the opening of the shrink tunnel exit area are performed only after the operation mode BM has been reached. The operating mode is reached if, for example, there is a predefined temperature in the interior of the shrink tunnel. In the exemplary embodiment shown, the opening of the shrink tunnel entrance area and the opening of the shrink tunnel exit area take place, in particular, first with one of those associated with the FIGS. 1 and 2 described process steps a) and / or b) and / or c) and / or d) and / or e) and / or f).

The invention has been described with reference to a preferred embodiment. However, it will be apparent to those skilled in the art that modifications or changes may be made to the invention without departing from the scope of the following claims.

Claims (5)

1. A method for converting a shrink tunnel to a production mode (PM) wherein the method comprises at least opening one shrink tunnel entrance section and/or opening one shrink tunnel exit section;
   wherein the method further comprises the following step:

   switching on the conveyance means of the shrink tunnel or raising the speed of the conveyance means of the shrink tunnel to a specified target value (V(F)-PM);

   characterized in that

   the method step of switching on the conveyance means or raising the speed of the conveyance means is performed in dependence on the progress of heating the shrink tunnel to a predefined target temperature (Ti-PM),

   wherein the time at which the conveyance means is switched on or at which the speed of the conveyance means is raised is set such that when passing through the shrink tunnel during the time which is required for heating the shrink tunnel to a final target value of a required temperature inside the shrink tunnel, all sections of the conveyance means are warmed sufficiently so that the conveyance means is overall heated to the necessary production temperature, and wherein the opening of the shrink tunnel entrance section and/or the opening of the shrink tunnel exit section are performed when the defined target value of the temperature inside the shrink tunnel has been reached.
2. A method as recited in claim 1 wherein the method additionally comprises at least one of the following steps:

   • switching on or increasing the chain cooling capacity to a specified target value (P(F)-PM);

   • switching on or increasing the bundle cooling capacity to a specified target value (P(G)-PM).
3. A method as recited in claim 2 wherein increasing the chain cooling capacity to a specified target value (P(F)-PM) is performed in dependence on the progress of heating the shrink tunnel to a predefined target temperature (Ti-PM), in particular to a measured temperature inside the shrink tunnel, and/or wherein increasing the chain cooling capacity to a specified target value (P(F)-PM) is performed in dependence on a measured temperature of the conveyance means.
4. A method as recited in one of the previous claims wherein the method additionally comprises a process step for assessing the position of the bundles being conveyed on the conveyance means and for performing the opening of the shrink tunnel entrance section and/or the opening of the shrink tunnel exit section in dependence on the assessed position and/or wherein an additional process step which switches a control unit of the shrink tunnel to a run mode, is performed before all other steps.
5. A method as recited in one of the previous claims wherein the opening of the shrink tunnel entrance section and the opening of the shrink tunnel exit section are performed at the same time and/or wherein the speed of the conveyance means is raised above the specified target value for a short time and at the earliest together with opening the shrink tunnel entrance section and/or with opening the shrink tunnel exit section.

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